10700 Mangrove Ecosystems

7/24/2019 10700 Mangrove Ecosystems

1/29

The Status of Mangrove Ecosystems:

Trends in the Utilisation and Management of Mangrove

ResourcesD. Macintoshand S. Zisman

1. Introduction:1.1 History of Mangrove Management; 1.2 Objectives of this Revie

2. !he Mangrove Resource: "ac#ground to $resent Day %&'(oitation:2.1 )rea andDistribution of Mangroves; 2.2 Mangrove "iodiversity and *'ecies +haracteristics;2., !he+hanging $attern of Mangrove %&'(oitation;2.- Regiona( %&am'(es: +entra( and *outh)merica/+aribbean and 0*)/ India and "ang(adesh/ *.%. )sia

,. Revie of *ectoria( )ctivities in Mangrove %cosystems: ,.1 Historica( $ers'ectives;,.2!imber and ue(ood: India and "ang(adesh/*.%. )sia/ *outh )merica/+aribbean/ +entra()merica;,., 3ood +hi's and $u('ood; ,.- 4on5ood orest $roducts; ,.6 )gricu(tureand *a(t $roduction; ,.7 +oasta( Industry and 0rban Deve(o'ment; ,.8 Mangrove5basedisheries;,.9 Mangroves and )uacu(ture: *hrim' farming/Other auacu(ture

-. Integrated *ystems of Mangrove Management: -.1 *ma((5sca(e *ystems; -.2 arge5sca(e*ystems

6. +onservation and Resource %nhancement:6.1 $rotection of "iodiversity;6.2 Mangrove)fforestation

7. uture !rends and $o(icy Deve(o'ment: 7.1 Ma''ing and Resource )na(ysis; 7.2 Integrated+oasta( 2?s the Ma(aysian orest De'artment/ for e&am'(e/ recognised

the (egitimate needs of fishermen for various secondary mangrove 'roducts/ but admittedthem to be @somehat ve&atious com'(ications@ in an otherise straightforard scheme forfue( and 'o(e ood 'roduction 3atson/ 1>29.
mailto:remote-printer.Dan_Macintosh/Institute_of_Aquaculture/[email protected]:remote-printer.Dan_Macintosh/Institute_of_Aquaculture/[email protected]:remote-printer.Dan_Macintosh/Institute_of_Aquaculture/[email protected]


2/29

rom such beginnings/ mechanisms for mangrove management have continued to evo(ve/ butsti(( (arge(y a(ong sectoria( (ines. Inevitab(y/ individua( agencies have a''roached coasta(resource management ith 'rejudices that (imit their 'riorities to those direct(y re(ated toagency jurisdiction and goa(s. Mu(ti'(e use management/ though much ta(#ed about/ is sti((the e&ce'tion in 'ractice/ rather than the ru(e. !he 'rob(em is succinct(y described by

!om(inson: @ ) forestry de'artment i(( em'hasise uti(isation that may degrade the resource/ afisheries de'artment i(( em'hasise conservation ith minimum of disturbance/ and anagricu(tura( de'artment may advocate conversion and re'(acement by some 'utative(y moreva(uab(e resource. !his conf(ict is the bac#ground to mangrove management...@ !om(inson/1>97.

!he (imitations inherent in the sectoria( a''roach are in fact/ no recognised as a majorconstraint to estab(ishing sustainab(e deve(o'ment of mangrove resources O(sen and )rriaga/1>9>; 4uruAAaman/ 1>>,. Other constraints inc(ude (ac# of enforcement "urbridge andMaragos 1>96; the 'oer of various e(ites to gain e&c(usive 'ro'erty rights to coasta(resources O(sen and )rriaga/ 1>9>; the (ac# of community in'ut into management efforts;

the 'overty status of many indigenous coasta( communities; and a (ac# of aareness amongstdecision ma#ers about the mangrove ecosystems they are dea(ing ith. !he (atter deficiency iscom'ounded by the com'(e& geogra'hica(/ 'hysica( and bio(ogica( nature of mangroves/ sincethey cover the intertida( Aone/ but a(so interact significant(y ith inshore/ u'stream andterrestria( ecosystems/ and su''ort a diverse fauna and f(ora of marine/ freshater andterrestria( s'ecies Macintosh/ 1>92; Danie( and Robertson/ 1>>?; Bohn and ason/ 1>>?;Robertson/ 1>>1; 04%$/ 1>>-.

*ince the (ate 1>7?@s/ the trend aay from at (east moderate(y sustainab(e mu(ti'(e use ofmangrove resources has been e&acerbated by many governments/ or by 'o(itica((y 'rotectedindividua(s/ see#ing to e&'(oit tro'ica( coasta( resources for 'ure(y financia( gain. Onee&am'(e is Indonesia@s 'o(icy to 'romote shrim' farming during the 1>9?s to increase foreigne&change earnings to offset a dec(ine in 'etro(eum e&'ort revenues.

+onseuent(y/ the human eco(ogy of mangrove areas has in many cases changed from a jointonershi'Cmu(ti'(e5use coasta( system into a 'rivate(y oned sing(e5'ur'ose one of (osustainabi(ity; the case of shrim' farms created out of mangroves is 'erha's the most

'ub(icised and ides'read e&am'(e and has affected coasta( communities around the or(d/inc(uding %cuador/ "ang(adesh/ !hai(and and ietnam e.g. Me(tAoff and i$uma/ 1>97;"ai(ey/ 1>99; Macintosh and $hi((i's/ 1>>2; )#sorn#oae/ 1>>,; Hong and *an/ 1>>,.

Ironica((y/ over the same 'eriod that these changes have ta#en '(ace/ the eco(ogica(/hydro(ogica(/ and socio5economic functions of mangroves and other et(ands have becomefar more ide(y a''reciated amongst the scientific community Bohn and ason/ 1>>?;Macintosh et a(/ 1>>1; 04%$/ 1>>-. !he u'stream/ donstream and on5site inter5actions onhich their various functions de'end are better understood/ and conseuent(y/ '(anners haveca((ed for a more integrative ho(istic frameor# for mangrove management.

!o 'rovide a frameor# hich ref(ects the com'(e& (in#ages of the mangrove ecosystem/ andto combat the (imitations of the sectarian a''roach/ a ne management a''roach is beingadvocated/ various(y #non as Integrated +oasta(


3/29

(arge(y due to the resistance of entrenched sectoria( interests ho 'erceive a (oss of 'rofit andautonomy under an integrated management structure.

O!ectives of this Revie"

!he objectives here are to describe the or(d@s mangrove resources/ identify ho theire&'(oitation and conventiona( management have affected the g(oba( resource as it e&ists today/then suggest ays in hich a more sustainab(e e&'(oitation can be o'erated/ ithin a modernmanagement a''roach. $articu(ar em'hasis is given to the auatic com'onent of mangroveecosystems/ because the serious state of mangrove fisheries and the high(y 'ub(icised im'actof coasta( shrim' farming on mangrove ecosystems have done much to inf(uence recento'inion that ne management strategies are urgent(y needed. *ome e&am'(es of integratedmanagement systems are 'resented based on traditiona( conce'ts/ or on 'i(ot sca(e attem'ts tointroduce modern a(ternatives as a com'onent of I+29; !om(inson/ 1>97; 04%$/ 1>>-.

Mangroves are estimated to e&tend over 16 mi((ion hectares or(d5ide acerda and Dio'/1>>,; there are about 7.> mi((ion ha in the Indo5$acific region/ ,.6 mi((ion ha in )frica andsome -.1 mi((ion ha in the )mericas inc(uding the +aribbean ig. 1; !ab(e 1. Hoeveraccurate(y defining the e&tent/ characteristics and dynamics of mangrove ecosystems has on(y

become 'ossib(e recent(y ith the avai(abi(ity of sate((ite imagery and =I* techniues e.g."(asco et a(/ 1>9>; Bensen et a(/ 1>9>; ibu(sresth et a(/ 1>>1. Detai(ed estimates of themangrove areas remaining in !hai(and/ based on andsat5M** data/ are shon in !ab(e 2 as

an e&am'(e.

!he most e&tensive and (u&urious mangroves e&tend across the Indo5$acific regions herethey are best deve(o'ed in the de(ta systems of major rivers/ e.g. the =anges5"rahma'utra/Irraady/ Me#ong and a(ong very she(tered shores 'rotected by (arge (and masses/ notab(yMadagascar/ the Ma(acca *traits/ Ea(imantan/ the Indonesian )rchi'e(ago and $a'ua 4e=uinea. !he (argest intact area of mangroves occurs in "ang(adesh/ here there is a(most7??/??? ha of the *undarbans ecosystem and a mangrove forest area estimated in 1>96 tocover -?1/7?? ha +haffey/ Mi((er and *andom/ 1>96.

In *outh )merica/ mangrove forests e&tend from northern $eru on the $acific coast and from

"raAi(@s southern state of Rio =rande do *u( on the )t(antic coast ig. 1. )ridity and the co(dHumbo(t current (imit the southern e&tension on the $acific side to about 7 degrees south/


4/29

hereas higher rainfa(( and arm currents a(ong the southern coast of "raAi( 'ermit mangrovegroth to about 29 degrees south *neda#er et a(. 1>97.

arge undisturbed forests remain in remote areas/ for e&am'(e the Orinoco De(ta in easterneneAue(a ->6/2?? ha and the $acific coast of +o(ombia -61/,?? ha. *imi(ar e&'anses

occur in northern "raAi( *neda#er et a(. 1>97. !he mangroves of the )mericas continuenorth a(ong both sides of the +entra( )merican isthmus. !he ,/>?? #m $acific coast has over,-?/??? ha of mangrove forests/ ith a higher f(oristic diversity than the +aribbeancommunity BimeneA/ in D@+roA et a(/ 1>>?.

Mangroves a(so 'enetrate some tem'erate Aones/ but there is a ra'id decrease in the numberof s'ecies ith increasing (atitude +ha'man/ 1>87; !om(inson/ 1>97. )t their (atitudina(e&tremes: ,1 4 in southern Ba'an Hoso#aa et a(/ 1>88; ,1 4 on the $acific coast ofMe&ico; ,2 * in "raAi( and ,9 * in southern )ustra(ia 3e((s/ 1>9, the mangrove vegetationis in each case restricted to a sing(e s'ecies. )rid c(imates a(so (imit

Mangrove #iodiversity and S(ecies *haracteristics

)bout 9? s'ecies of true mangrove treesCshrubs are recognised/ of hich around 6?57?s'ecies ma#e a significant contribution to the structure of mangrove forests. *'ecies diversityis much higher in the *outheast )sian region/ here a''ro&imate(y to5thirds of a(( s'eciesare found/ hi(e a''ro&imate(y 16 s'ecies occur in )frica and 1? in the )mericas. !he treesof severa( genera are va(uab(e for timber or fue(ood/ es'ecia((y RhiAo'hora s'ecies hichoccur in a(( three regions. )(though mangroves thrive best a(ong she(tered humid tro'ica(coast(ines here a((uvia( sediments can accumu(ate as a substratum for mangroveco(onisation/ mangroves a(so occur as fringes or 'atches in carbonate sediments a(ong sma((is(and shores/ as in the +aribbean %((ison/ 1>>,.

)rid c(imates a(so reduce s'ecies diversity and restrict mangrove groth to (o shrubformations in e&treme cases/ as in 4orthern Fueens(and and a(ong the $ersian =u(f and Red*ea coasts. !he effect of aridity rather than (atitude on mangrove communities is e((demonstrated in India. %&c(uding the )ndaman and 4icobar is(ands/ about 6?G of India@smangrove resource is found in the =anges de(ta of 3est "enga( *underbans and com'risesmore than 2? s'ecies/ hereas at simi(ar (atitudes on the arid est coast =ujarat on(y about12G of the tota( resource and nine s'ecies occur ishas/ +havan and 0ntaa(e/ 1>>,.

The *hanging %atterns of Mangrove Utilisation

*aenger et a(. 1>9, attribute the genera( cause of mangrove destruction and degradation tothe 'reference for short5term e&'(oitation for immediate economic benefit/ rather than (onger5term but sustainab(e e&'(oitation. %&'anding on their basic c(assification/ five s'ecific ty'esof human interference causing mangrove destruction can be suggested:5

1. over5e&'(oitation by traditiona( users/ e.g. e&cessive remova( of trees for fue( ood/es'ecia((y charcoa(;

2. activities reuiring maintenance of the mangrove ecosystem/ e.g. rotationa( fe((ing andre'(anting of mangrove stands for ood 'roduction;

,. natura( resource activities destroying the mangrove resource hich reuire (itt(e or no

in'uts from it/ e.g. coasta( agricu(ture; sa(t 'roduction; intensive shrim' cu(ture;


5/29

-. other activities/ genera((y unre(ated to the mangrove ecosystem/ hich com'(ete(ydestroy it/ e.g. harbours/ factories and other forms of coasta( industria(isation orurbanisation;

6. off5site activities unre(ated to the mangrove ecosystem but detrimenta( to it/ e.g.offshore dredging/ coasta( 'o((ution/ diversion of u'stream freshater sources for

irrigation.

In genera( there is an increasing rate or sca(e of im'act associated ith the above and a givenmangrove area can be affected by severa( different activities simu(taneous(y/ or over time as(and use 'atterns change. !he mangroves hich used to fringe the inner =u(f of !hai(and inthe 'rovinces of *amut *a#horn and *amut *ong#ram are a good e&am'(e. !oday these

'rovinces are a(most devoid of mangroves !ab(e 2/ but origina((y the mangroves eree&tensive; they ou(d have served 'rinci'a((y as fishing grounds for (oca( 'eo'(e and a sourceof ood 'roducts. !he inner mangroves ere c(eared/ starting severa( decades ago/ to createsha((o 'onds for sa(t 'roduction and cana(s ere constructed through the mangroves foraccess and to carry seaater to the sa(t 'ans. 3i(d shrim' 'roduction in the et season/

a(ternating ith sa(t 'roduction in the dry season/ as introduced from about the 1>,?s/giving a further economic reason for mangrove conversion by (oca( 'eo'(e.

3ith the deve(o'ment of intensive shrim' farming techniues in !hai(and in the 1>9?s/ thereas a sudden rush into modern shim' farm construction by dee'ening the sa(t 'onds orconverting (arge areas of the remaining mangroves. 4ear(y a(( the investment as bycom'anies and non resident businessmen. "y 1>9> shrim' 'roduction in these 'rovinces hadco((a'sed because the environmenta( carrying ca'acity as e&ceeded $hi((i's/ 1>>-. Muchof the (and is no un'roductive and aaits redeve(o'ment into factory or housing estates.

!he mangrove degradation and destruction that resu(ts from such activities are a(soaccom'anied by an acce(erating remova( of common 'ro'erty benefits in mangroveecosystems i.e. 1.above/ to forms that can accrue to 'rivate concerns i.e.25- above"urbridge 1>89; Me(tAoff and i$uma/ 1>97.

Regional E'am(les

Having estab(ished an ana(ytica( frameor#/ changing 'atterns of mangrove use i(( bee&amined for different regions of the or(d.

*entral and South )merica

In +entra( )merica/ archaeo(ogica( evidence has confirmed the use of mangrove fue(ood insa(t 'roduction dating bac# to before the *'anish 'eriod. It is a(so (i#e(y that there as a rangeof subsistence harvesting from the mangroves associated ith a string of sma(( coasta(sett(ements fishing/ hunting/ fireood and 'o(e ood e&traction/ etc. too# '(ace McEi((o'and Hea(ey/ 1>9>; Befferson and Ee'ecs/ 1>9>.

*ince the +o(onia( 'eriod/ e&'(oitation of the +entra( )merican coast has intensified/ a(thoughmuch more so a(ong the $acific shore. *'anish co(onists (eft a(most the entire +aribbeancoast/ from the ucatan don to $anama/ to the native Indians eonard/ 1>98. Remova( ofnatura( resources as underta#en s'oradica((y by the %ng(ish from tem'orary sett(ements in

the 19th and ear(y 1>th centuries/ but neither this nor subseuent deve(o'ment has muchaffected mangrove on a significant sca(e/ other than in $anama here c(earance for charcoa(

'roduction has significant(y reduced the mangrove resource. In contrast/ the mangroves a(ong


6/29

the $acific coast have been substantia((y reduced/ through conversion to agricu(ture/auacu(ture/ industry and sett(ement/ and by over5e&'(oitation for fue( and constructionmateria(s.

In +entra( )merican/ recent threats to mangroves have been revieed by eonard 1>98. His

findings sho that in =uatema(a and %( *a(vador/ direct use for charcoa( 'roduction and thee&traction of tannin have been res'onsib(e for (arge sca(e mangrove remova( and degradation.Indirect damage has resu(ted from agricu(tura( runoff/ 'articu(ar(y from the cotton groingareas of the $acific coasta( '(ain. In Honduras/ sa(t e&traction has caused mangrovedestruction. $o((ution from sediments/ 'esticides/ industry and seage are significant factorscontributing to mangrove degradation.

)s a conseuence of e&traction for charcoa( and tannin 'roduction/ combined ith theindirect im'acts from sediment and 'esticide 'o((ution/ it is estimated that the mangrove areain =uatema(a has been reduced by >2G since the (ate 1>6?s eonard/ 1>98. In +osta Rica/-?G of the origina( mangrove cover had gone by 1>8>/ due 'rimari(y to tannin 'roduction/

auacu(ture/ sa(t 'roduction and coasta( deve(o'ment.

!hreats to 4icaragua@s mangroves occur main(y on the $acific coast. )(though detai(edinformation is (ac#ing/ it is (i#e(y they are under simi(ar 'ressures to mangroves in Honduras.In +osta Rica/ major causes of mangrove destruction have been tannin 'roduction no

banned/ shrim' auacu(ture/ sa(t 'roduction/ coasta( deve(o'ment/ and to a (esser e&tent thanin =uatama(a and %( *a(vador/ cutting for fue(ood and 'o((ution from agricu(ture. $anamahas e&'erienced substantia( a(teration of its mangroves. +utting for charcoa( and tannin

'roduction/ and infi((ing for urban and resort deve(o'ment have a(( been res'onsib(e. "e(iAe isthe on(y country here eonard 1>98 considered that mangroves ere not beingsignificant(y degraded or e(iminated/ a(though there is current(y (oca(ised c(earances for urbane&'ansion and tourism deve(o'ment >2.

BimeneA in D@+roA et a(/ 1>>? considers mangrove destruction to have been 'oor(ymonitored in +entra( )merica/ but uotes re'orted (osses of ,96 haCyr in 4icaragua ega1>9-/ 67?haCyr for =uatama(a Ro((et 1>97 and -6haCyr for +osta Rica BimeneA 1>>?.Most of the conversion he suggests/ has been for rice fie(ds/ 'asture/ sa(t eva'oration 'onds/and more recent(y/ shrim' 'onds. He further suggests hoever/ that the most seriousmangrove management 'rob(em in +entra( )merica is not conversion but degradation/through overcutting for fue( here ood is the main energy source e.g. %( *a(vador andfrom 'esticide contamination in %( *a(vador and 4icaragua originating from cotton and

aterme(on cro's.

In *outh )merica/ historica( uses of mangroves are re(ative(y 'oor(y documented/ a(thoughIndians are #non to have inhabited coasta( areas characterised by e&tensive mangroveforests *neda#er et a(. 1>97. $resumab(y/ 're5+o(ombian uses ere simi(ar to thesubsistence activities observed today/ 'rimari(y the cutting of trees for fireood/ charcoa(/ and

'o(es for (ight construction/ domestic use and fish tra's. !hese ere (i#e(y to be sma(( sca(eo'erations carried out by sing(e fami(ies or individua(s from each vi((age *neda#er et a(.1>97. *idda(( et a(. 1> do hoever/ refer to o'en5system auacu(ture by the Inca in%cuador as (ong ago as -?? years.

%ven in more recent times/ the neotro'ica( mangroves have not/ ith certain e&ce'tions/ beenmanaged or uti(ised beyond the 'rovision of subsistence needs for (oca( 'o'u(ations. $art ofthe reason for the benign neg(ect is the fact that the majority of major 'o'u(ation centres ere


7/29

initia((y (ocated in high a(titude environments eg "ogota/ +o(ombia enjoying a coo(er morefavourab(e c(imate and (oer incidence of diseases such as ye((o fever and ma(aria*neda#er et a(. 1>97.

*ariean and US)

!he origina( mangrove resources of the +aribbean ere re(ative(y vu(nerab(e/ being confinedby a combination of stee' to'ogra'hy/ sma(( estuaries and sma(( tida( range. ) significant'ro'ortion of mangroves ere removed by ear(y sett(ers for fue( in sa(t 'roduction.*ett(ements a(ong the coast have been the main cause of modern c(earance/ ith a significant

'ro'ortion of this being re(ated to the 'rovision of tourist infrastructure.

ugo 1>99 gives the origina( area of mangroves for $uerto Rico at ,?/??? ha. "y 1>86 6?Ghad been (ost. osses are attributed to trans'ort/ housing/ marinas and (andfi((/ ith recreationand 'o((ution degrading additiona( areas. *aenger et a(. 1>9, cite 'o((ution from seage andindustria( aste as significant causes of mangrove degradation in the esser )nti((es

=uade(ou'e and Martiniue.

or the +aribbean/ ugo et a(. 1>99 give conversion to agricu(ture and c(earance for fue((edand charcoa( 'roduction as ear(y causes of mangrove (osses/ ith c(earance for touristfaci(ities/ housing and roads arising as more recent threats to surviving stands. In contrast/ inHaiti and the Dominican Re'ub(ic the need for chea' fue( has (ed to e&tensive mangrovesc(earance/ hereas tourism is not high(y deve(o'ed.

In the 0*)/ agricu(tura( conversion has been the 'rinci'a( cause of (oss of et(ands overa((/but for mangroves restricted by c(imate to the south5eastern states the 'rimary causes aredifferent/ ith housing/ industry/ and drainage for disease vector contro( being the main

factors "urbridge 1>89.

India and #angladesh

arge areas of the in(and mangroves of southern )sia have been converted to agricu(turemain(y 'addy fie(ds or sa(t 'roduction. *hrim' farming re'resents a re(ative(y ne form ofcoasta( (and use hich is a further threat. Bagta' et a( 1>>, cite an overa(( area( (oss ofmangrove in India of ,-G beteen 1>86 and 1>>?5>1/ euiva(ent to 1-9/6?? ha/

!raditiona((y the mangroves of India and "ang(adesh have been e&'(oited for timber andfue(ood/ bar# tannin/ anima( fodder/ native medicines and food fish/ she((fish/ honey/ i(danima(s. $o'u(ation 'ressure has great(y increased the rate of e&'(oitation/ (eading todegradation of the remaining forests at an a(arming rate. In "ang(adesh/ here an estimated,??/??? ood and thatch cutters/ honey co((ectors/ and fishermen are direct(y de'endent onthe *undarbans/ the area of 'ure sundri Heretiera fomes 5the main economic timber s'eciesis re'orted to have shrun# from ,1.7 to 21.?G beteen 1>6> and 1>9, +haffey/ Mi((er and*andom/ 1>96.

!o'5dying of sundri as e(( as over5cutting is b(amed for this situation/ but the die5bac#'rob(em seems to be associated ith increased sa(inity arising at (east 'art(y from (arge sca(ediversion of freshater 5 an indirect form of human im'act on the *undarbans mangroves.

Southeast )sia


8/29

Huge areas of mangrove have been (ost from *outheast )sia due to ood e&traction/conversion to agricu(ture or sa(t 'roduction/ coasta( industria(isation and urbanisation and/conversion to coasta( auacu(ture !ab(e 1. Recent(y/ shrim' farming has been b(amed for(arge sca(e (osses in severa( countries/ notab(y !hai(and/ Indonesia and the $hi(i''ines.%stimates of the mangrove areas destroyed for different 'ur'oses in !hai(and are shon in

!ab(e 6. !hese revea( the re(ative im'ortance of auacu(ture as a cause of mangrovedestruction since 1>9?/ but a greater tota( (oss of a(most 8?/??? ha 'rior to 1>9? due to main(yto agricu(ture and coasta( infrastructure deve(o'ments. !he tota( mangrove resource in!hai(and has shrun# from an estimated ,79/1?? ha in 1>71 )O/ 1>92 to 1>7/7-, ha in1>97598 )#sorn#oeae/ 1>>,.

Revie" of Sectarian )ctivities in Mangrove Ecosystems

Historical %ers(ective

Historica((y mangrove ecosystems have been sites of human sett(ement throughout the

tro'ics/ es'ecia((y in the India5$acific region. !his is understandab(e since mangrovesdominate in she(tered (ocations/ offer e&tensive navigab(e channe(s for boats and 'rovidedear(y sett(ers ith an abundant source of bui(ding materia(s/ fue((ed/ thatching/ bar# a sourceof tannin/ medicines/ etc./ as e(( as e&ce((ent gathering/ hunting and fishing environmentsfor food see !ab(e ,.

!he ide variety of traditiona( 'roducts from mangroves uti(ised by coasta( communities ise(( documented Hami(ton and *neda#er/ 1>9-; +han and *a((eh/ 1>98. Many of theseactivities sti(( continue/ and inc(ude co((ection of thatching materia( 4y'a/ gathering ofshe((s to 'roduce (ime and i(d honey co((ection in the *undarbans es'ecia((y. 3hi(e ear(y

coasta( sett(ers enjoyed great se(f sufficiency in this ay/ and some human communities sti(((ive in an integrated ay ithin mangrove environments/ commercia( e&'(oitation ofmangrove resources/ es'ecia((y for timber and fue(ood/ deve(o'ed ra'id(y to su''(y thegroing needs of urban 'o'u(ations. %ven among traditiona( communities/ increasing

'o'u(ation 'ressure on coasta( resources has inevitab(y (ed to a gradua( degradation ofmangroves as more and more forest has been cut to satisfy (oca( timber and fue(ood needs.

Timer and +uel"ood

In vo(ume terms/ timber 'roduction from mangrove forests has been minor in com'arison tothat from other forest ty'es/ 'rimari(y due to timbers of su'erior ua(ity being avai(ab(e in

tro'ica( in(and forests 3atson 1>29 and difficu(ties of access and trans'ort associated iththese et(ands. Hoever on a (oca( sca(e/ mangrove timber has a(ays been im'ortant totraditiona( coasta( communities for house and boat bui(ding )O/ 1>92/ and remains sotoday. In the "ang(adesh *undarbans/ timber yie(ds/ 'rinci'a((y of Heritiera fomes sundriand %&coecaria aga((ocha gea/ have e&ceeded ,??/??? cubic metres annua((y )O/ 1>92/re'resenting a major source of ood in a country 'oor(y endoed ith other forest ty'es.%(sehere/ by far the greatest use of mangrove ood is for fue(/ es'ecia((y charcoa( becauseof the e&ce'tiona( s(o5burning 'ro'erties of the ood of RhiAo'hora s'ecies. 3ood sti((

'rovides >?G of the fue( used in ietnam *+/ 1>>, for e&am'(e/ hence the great 'ressureon mangroves a(ong heavi(y 'o'u(ated coast(ines such as in ietnam.

+om'(ete forest management '(ans for sustainab(e 'roduction from mangrove forests are(imited to the )sian region e.g. +urtis 1>,,/ Di&on 1>6>/ Ehan 1>77/ +houdhury 1>79. 4o


9/29

such schemes e&ist in *outh )merica a(though some internationa( organiAations such as )Ohave made efforts to deve(o' '(ans for se(ected mangrove forests.

India and #angladesh

Heavy e&'(oitation of mangroves in India for fireood and anima( fodder has de'(eted theresource significant(y/ e&ce't in the Indian *underbans and the )ndaman Is(ands herese(ective systems of rotationa( fe((ing have been 'racticed "(asco/ 1>86. 0ntaa(e 1>89uoted 'roduction annua((y of a(most 26/??? t of timber '(us a(most 17??? t of fireood fromthe Indian *undarbans/ based on fe((ing cyc(es of 2? years in Heritiera dominated forest/ or ,?and -? years in forests dominated by %&coecaria or +erio's/ res'ective(y. In addition tofireood/ stri' fe((ing as carried out in the )ndamans to e&tract 'o(es of "ruguieragymnorrhiAa/ ith successfu( re'(anting of "ruguiera seed(ings re'orted see )O/ 1>92.

!he (argest sing(e area of mangroves in the or(d (ies in the "ang(adesh 'art of the*underbans/ covering an area of a(most 7??/??? ha inc(uding aterays/ and is the on(y (arge

mangrove forest managed for commercia( timber e&traction in )sia +hristensen/ 1>92. )snoted above/ e&'(oitation of the "ang(adesh *underbans mangroves for timber has e&ceeded,??/??? t annua((y/ but yie(ds have dec(ined in recent years as (arge trees have becomescarcer. !he @sundri@ tree Heritiera fomes is the most im'ortant timber yie(ding s'ecies*iddii and *iddii/ 1>>?. ue(ood is the second major 'roduct.

orest management '(ans for the *undarbans date bac# to the 198?s described by +haffee/Mi((er and *andam/ 1>96. %ar(y overcutting resu(ted in a dec(ine in the standing stoc#s of thefour main economic s'ecies. !he most com'rehensive '(an as 're'ared for the 'eriod 1>,1to 1>61 +urtis/ 1>,,. !his had five or#ing circ(es/ three of hich ere in hat is no the"ang(adesh 'ortion of the *undarbans. !he or#ing circ(es ere based on eco(ogica( criteria

and identified as the freshater/ moderate(y sa(tater and goran +erio's decandra circ(es.!enty year fe((ing cyc(es ere s'ecified for the freshater and goran circ(es and ,? years forthe moderate(y sa(tater circ(e. +om'artments ere the basic management unit and four standua(ities ere recognised/ based on average ma&imum tree heights. *ubseuent(y this assim'(ified to three stand ua(ities and in each cutting com'artment each tree s'ecies had asing(e diameter (imit.

!he ne&t major or#ing '(an after +urtis 1>,, covered the 'eriod 1>7?571 to 1>8>59?+houdhury/ 1>79 and continued to be more or (ess fo((oed thereafter. )n OD) forestryteam com'(eted a ne inventory/ ith management recommendations/ in 1>96/ but these havenot been im'(emented "ang(adesh orest de'artment 'ersona( communication and a neinventory by an )O team i(( begin in 1>>65>7. +houdhury@s management '(an is based on2? year cutting cyc(es and defines three or#ing circ(es: gea %&cecaria ga((ocha/ sundriHeritiera fomes and #eora *onneratia a'ete(a. )(( tree fe((ing is done by contractors undersu'ervision by the De'artment of orestry officers and based on minimum diameters fi&ed foreach com'artment; a roya(ty is 'aid on a unit vo(ume or (ength basis detai(ed in +haffey/Mi((er and *andom/ 1>96. !here is no re'(anting after fe((ing.

Southeast )sia

!he mangrove forest '(ans o'erating in *outheast )sian countries/ 'rinci'a((y in Ma(aysia/

!hai(and/ ietnam and Indonesia/ have been the subject of many revies )O/ 1>92/ 1>96;)#sorn#oeae/ 1>>,; Hong and *an/ 1>>,;. In Indonesia/ commercia( e&'(oitation ofmangroves for charcoa( is re'orted from 1998 in *umatra Be((es/ 1>2> but/ des'ite ear(y


10/29

attem'ts to introduce forest or#ing '(ans/ mangroves ere e&'(oited ith (itt(e managementcontro(s unti( the 1>8?s )O/ 1>92. *ince then/ (arge areas of @'roduction@ forest have beenassigned to concession ho(ders/ but ith regu(ations concerning their activities introduced by(a in 1>89. +oncessions tota((y -66/??? ha ere o'erating in the 1>9?s cited by )O/1>96.

!he ru(es reuire concessionaires to ma#e an inventory of the concession area and to (eave a'rotection Aone of undisturbed mangrove at (east 6? m ide at the seaard margin of a siteand at (east 1? m ide a(ong river ban#s; annua( cutting (imits are set by the Directorate=enera( of orestry. orty seed trees 'er hectare minimum diameter 2? cm must be (eft afterfe((ing/ or 26?? seed(ings '(anted at a s'acing of 2m & 2m. )s ith other mangrovemanagement systems/ the main 'rob(ems are associated ith effective im'(ementation andsu'ervision of these regu(ations.

South )merica

)ccording to *neda#er et a(. 1>97/ (arge sca(e mangrove forest management in *outh)merica is considered to e&ist on(y at the '(anning stage/ ith the governments of "raAi(/$anama/ and eneAue(a deve(o'ing or#ing '(ans not necessari(y for sustainab(e

'roduction. In the (atter e&am'(e/ Hami(ton et a(. 1>9- does note the harvesting of (argeRhiAo'hora in the Orinoco de(ta for 'oer uti(ity 'o(es. Otherise/ *neda#er et a(. 1>97consider '(ans for mangrove forest e&'(oitation in *outh )merica to be high(y e&'(oitive; e.g.c(ear fe((ing for sa(e to internationa( oodchi' buyers. Detai(s of such an o'eration in theOrinoco De(ta in eneAue(a are given in *aenger et a(. 1>9,.

*ariean

%ven though the e&tent of Dominican mangroves is so (imited/ 'o(es are harvested from themain stands of hite mangrove aguncu(aria racemosa )r(ington 1>99.

*entral )merica

!he main commercia( activity in $anama@s mangrove is the harvesting of 'o(es 217/126 cubicmetres a year BimeneA in D@+roA et a(. 1>>?.

igures from 'ermits suggest that in 4icaragua -???58??? cubic metres of mangrove areharvested annua((y for 'o(es ega 1>9-/ ith a further 6??? cubic metres annua((y for othertimber ibid.

In Honduras/ beteen 9?/??? and 12?/??? cubic metres of mangrove are estimated to be usedfor fireood annua((y (ores 1>9,/ Ro((et 1>97 a(though this is (arge(y for use in sa(t

'roduction. In 4icaragua/ according to the 'ermits granted/ >/??? cubic metres a year areco((ected for fireood BimeneA in D@+roA et a(/ 1>>?/ and according to ega 1>9-/ the %(*a(vador harvest is a''ro&imate(y ,?/??? cubic metres a year Miranda/ 1>9,.

"oth BimeneA in D@+roA et a(./ 1>>? and *neda#er et a(. 1>97 consider charcoa('roduction in +entra( and *outh )merica to be re(ative(y inefficient. $anama is the maincentre of 'roduction/ 'roviding smo#e(ess fue( for the urban midd(e c(ass.

+harcoa( 'roduction in $anama demands around 8--9 cubic metres of mangrove a year/'rimari(y ta#en from stems of (ess than 26cm dbh D@+roA et a(. 1>>?. In the !erraba5*ier'earea of +osta Rica/ 1,?? cubic metres of charcoa( is 'roduced annua((y +hong 1>99. *idda((


11/29

et a(. 1> a(so consider charcoa( 'roduction as a significant cause of mangrove (oss in%cuador.

,ood *hi(s and %ul("ood

arge sca(e conversion of mangroves for ood chi' 'roduction began in %ast Ma(aysia andIndonesia during the 1>8?s. !o ood chi' mi((s ere estab(ished in *abah in 1>81 and a(icence for 16 years as granted for a concession of a(most 6?/??? ha to 'roduce ood chi's/main(y for e&'ort to Ba'an for rayon manufacture. Ma(aysia ha(ted this 'ractice thereafter/ butmangrove ood chi's are sti(( a major e&'ort from Ea(imantan accounting for the (oss ofthousands of hectares of forest 'ersona( observation. *oemodihardjo 1>89 mentions aconcession of ,6/??? ha of mangrove in *u(aesi for 'u('ood 'roduction. +(ear(y such

'ractices are unsustainab(e and they on(y continue in Indonesia because there are sti(( (argetracts of mangrove ith very (o human 'o'u(ation (eve(s/ as in %ast Ea(imantan.

-on"ood +orest %roducts

Tannin

!he ear(iest historica( record of mangrove use for *outh )merica is inferred from a (a'romu(gated by Eing Bose of $ortuga( in 187?. !he (a/ im'osed on "raAi(/ made it i((ega( tofe(( mangrove trees ithout simu(taneous(y uti(ising the bar# for tannin. It as feared thate&tensive c(earing for fireood ou(d reduce the bar# avai(ab(e for the tanneries. In additionto a financia( 'ena(ty/ the (a a(so im'osed a three month jai( term Hami(ton et a(. 1>9-.

*ma((5sca(e tannin 'roduction did 'ersist/ using the bar# from fe((ed RhiAo'hora. ) sma((industry e&isted in "e(iAe for e&am'(e/ during the 1>6?s >2/ but in common ith

other sites/ 'roduction as e(iminated by the subseuent co((a'se of the or(d tannin mar#etin the 1>7?s.

It continues at on(y a very fe sites in +entra( and *outh )merica. One of the (arger'roducers is (ocated in southest +osta Rica/ using bar# i((ega((y e&'orted from $anama*neda#er et a(. 1>97. *idda(( et a(. 1> give more detai(s/ noting that a(though +osta Ricahas banned mangrove harvesting/ a $anamanian coo'erative harvests red mangrove bar# tosu''(y +osta Rica@s (eather tanning industry. More than 8??/???#g of red mangrove bar# eree&'orted to +osta Rica in 1>91 for e&am'(e/ re'resenting the cutting of as much as 26? ha ofmangrove.

BimeneA in D@+roA et a(./ 1>>? uotes bar# harvests of 127? tonsCyr for Honduras Ro((et1>97 and -,8 tonsCyr for $anama. "ar# yie(ds for mangroves in +osta Rica range from 19-?to -->? #gCha BimeneA 1>>?. He notes that the 'reference for (arger trees J 26cm dbh in

bar# co((ection resu(ts in e&traction having a greater im'act than other common forms ofharvest such as 'o(es and charcoa( hich use sma((er stems BimeneA/ in D@+roA et a(./ 1>>?.

!he im'ortance of bar# tannins has dec(ined in many )sian countries/ but some mangrovetannin is sti(( used in India and "ang(adesh for (eather curing and there are some othertraditiona( uses/ e.g. for curing fishing nets in *ri an#a )O/ 1>92. !he gathering ofmangrove (eaves )vicennia for anima( fodder remains ides'read in the Midd(e %ast and

*outhern )sia/ for feeding came(s in Iran and India/ for e&am'(e; in fact graAing by domesticanima(s is a serious cause of mangrove degradation in 'arts of India 'ersona( observations.


12/29

Other %roducts

Mangrove honey is an im'ortant economic 'roduct e&tracted from the *undarbans4uruAAaman/ 1>>,. )(though im'ossib(e to uantify/ hunting a(so remains a significantactivity in the *underbans and in many other areas in )sia here mangroves are sti((

e&tensive. 0nfortunate(y/ this e&tends beyond hunting to su''ort (oca( food needs/ into the'oaching of rare and endangered s'ecies for sa(e as s#ins and stuffed s'ecimens for touristmar#ets 4uruAAaman/ 1>>,. !o a (imited degree native medicines see !ab(e - andmisce((aneous '(ant e&tracts e.g. a fish 'oison is obtained from the Derris '(ant and fooditems are sti(( co((ected from mangrove forests +han and *a((eh/ 1>98. !he e&'(oitation andva(ue of auatic 'roducts from mangrove ecosystems is/ hoever/ of far greater significancetoday/ as described be(o.

)griculture and Salt %roduction

In )sia (arge tracts of bac# mangroves ere c(eared initia((y for agricu(ture/ es'ecia((y rice

farming revieed by )O/ 1>92. Other suitab(e cro's inc(ude coconut and oi( 'a(m andeven 'inea''(e. Rice farming can be successfu( on mangrove soi(s in the et season/ a(thoughyie(ds are on(y moderate. Hoever in many such areas the soi(s are a((uvia( in origin and haveacid su('hate or 'otentia( acid su('hate characteristics hich (ead to a ra'id reduction in rice

'roduction ithin a fe years due to acidity/ iron and a(uminium to&icity and (ac# ofavai(ab(e nutrients/ after hich they are abandoned )O/ 1>92. !hese soi( 'rob(ems can becountered by the use of (ime and ferti(isers/ but it may not be economica((y viab(e to do so.or e&am'(e/ ferti(iAed 'otentia((y acid su('hate soi(s in the eastern region of the "ang#o#

'(ain 'roduced 1/>-? #gCha/ hereas yie(ds from non acidic mangrove soi(s in the esternregion reached ,/??? to -/??? #gCha cited by )O/ 1>92.

*a(t ater intrusion is another 'rob(em hich can destroy coasta( rice cro's; this is a freuentoccurrence in centra( ietnam/ for e&am'(e/ due to high aves generated by ty'hoons.+onversion of mangroves to rice agricu(ture is not common in *outh )merica *neda#er et a(.1>97.

In many 'arts of )sia the environmenta( and economic (imitations of coasta( rice farminghave been overcome by a(ternating the rearing of shrim' ith a rice cro' in the same fie(d/ or

by converting com'(ete(y to shrim' farming. In the Ehu(na District of "ang(adesh/ 'o(deredrice fie(ds @ger@ are f(ooded ith brac#ish ater in the dry season months for shrim' cu(ture/then a rice cro' is gron in the et season hen the fie(d can be f(ushed ith freshater e.g.

4uruAAaman/ 1>>,. or economic reasons associated ith the high 'rice of shrim'/ such'artia( or com'(ete sitches from rice farming to auacu(ture are 'utting further 'ressure onthe remaining mangroves.

)(though (ess obvious than habitat (oss/ the indirect effects of agricu(ture on mangroves/through the diversion of freshater by agricu(tura( irrigation schemes/ or run5off ofagricu(tura( chemica( residues into mangroves/ have a(so been significant in some cases. !heinterce'tion of natura( freshater f(o into mangroves and its diversion for irrigation

'ur'oses is a factor associated ith deteriorating mangrove conditions in the Indus De(ta andin the estern 'art of the *undarbans e.g. +haffey/ Mi((er and *andom/ 1>96.

)(though very (itt(e information is avai(ab(e/ there is great concern in )sia regardingenvironmenta( im'acts from agricu(tura( 'esticides/ some of hich are #non to be high(yto&ic to shrim' Macintosh and $hi((i's/ 1>>2. !he effects of antibiotic residues from the


13/29

treatment of bacteria( diseases in intensive shrim' farming is of simi(ar concern. In bothcases/ such chemica(s are (i#e(y to enter mangroves ith discharge or run5off aters.

In many regions of )sia ith a seasona((y dry c(imate/ (arge areas of mangrove ere c(earedin ear(y times for so(ar sa(t 'roduction e.g. !ab(e 6. !oday there are sti(( areas devoted

entire(y to sa(t 'ans e.g. centra( ietnam/ e(sehere/ sa(t 'roduction is rotated ith shrim'farming in the et season/ as in the +o&@s "aAaar area of "ang(adesh described by

4uruAAaman/ 1>>,. "ecause of the (o va(ue of sa(t/ some sa(t 'an areas have subseuent(ybeen converted into modern shrim' farms/ e.g. in the inner =u(f of !hai(and..

*oastal Industry and Uran &evelo(ment

In addition to the 'hysica( (oss of mangroves through coasta( industria(isation/ there are a(soconcerns over environmenta( effects from 'o((ution. "urns et a( 1>>, note that there ere168 major oi( s'i((s in tro'ica( seas beteen 1>8- and 1>>?. Dee' mud coasta( habitats mayta#e 2? years or more to recover from the to&ic effects of such oi( s'i((s.

Mangrove #ased +isheries

Over the 'ast to decades or so/ research has generated a (arge vo(ume of data su''orting thevie that there is an im'ortant (in#age beteen mangrove ecosystems and fisheries

'roductivity. !he basis of this re(ationshi' seems to be that mangroves 'rovide a ane&tensive three dimensiona( environment for fish and she((fish/ es'ecia((y to the juveni(estages i.e. a nursery habitat; and b detritus e&'orted from mangroves 'rovides a majorenergy source in tro'ica( coasta( aters to su''ort high 'roductivity in food chains invo(ving(arge numbers of detritus5feeding s'ecies/ such as mu((ets and 'enaeid shrim'. Many highva(ue/ commercia((y e&'(oited fish and she((fish uti(iAe mangroves during 'art of their (ifecyc(es/ inc(uding hite shrim' $enaeus merguiensis/ $. indicus/ $. vannemei/ grou'ers%'ine'he(us tauvina/ sea5'erch ates ca(carifer/ mud crab *cy((a serrata/ mi(#fish+hanos chanos and mu((ets iAa s''..

)(though the e&act degree of mangrove de'endency of such s'ecies is argued by scientists/ itis c(ear from fishery catch data that (arge areas of mangrove su''ort high yie(ds of fish andshe((fish.

Mangroves and )/uaculture

Over the (ast tenty years one of the greatest 'erceived threats to mangrove resources hasbeen the ra'id increase in coasta( auacu(ture and/ in 'articu(ar of shrim' farming.

!he main motivation of tro'ica( coasta( auacu(ture is financia( 'rofit/ not the 'roduction offood for (oca( consum'tion; coasta( communities invariab(y have a reasonab(e su''(y ofchea'Cca'tured seafood ith hich fe cu(tured 'roducts can com'ete in 'rice. Ironica((y/this source of natura( food is no under threat in many areas/ due to the demands of coasta(auacu(ture remova( of young fish and she((fish to su''(y cu(ture o'erations/ fisheries habitat(osses es'ecia((y nursery sites and 'o((ution 5 chief(y from intensive shrim' farming hereits main function is income generation 5 the 'roduction of cash cro's to be so(d to distant/often e&'ort/ mar#ets +savas/ 1>>?.

+oasta( auacu(ture 'roduction in 1>>? amounted to a''ro&imate(y 8.6 mi((ion tonnes orthan estimated 0*K1,/2,? mi((ion )O/ 1>>2. 3hi(st this is undoubted(y a (egitimate


14/29

economic aim/ (itt(e of the 'rofits accrue direct(y benefit the coasta( communities/ eventhough it is they ho suffer from the orst e&cesses of auacu(tura( deve(o'ment $rimavera/1>9>/1>>-; ee and 3ic#ins/ 1>>2. =iven the chance to e&'ress their 'references/ (oca(communities in many regions ou(d o't for (abour intensive/ (o cost techno(ogy o'erationsthat are more in #ee'ing ith socia( structures and environmenta( resources than (arge

im'orted farm businesses that enc(ose ide areas of (and. ee and 3ic#ins/ 1>>2.

In its 'ristine state the mangrove forest '(ays an im'ortant 'hysica( ro(e in re(ation to tro'ica(coast(ines and offers various niches to many '(ant and anima( s'ecies. )s a resu(t mangroves

'rovide a ide variety of goods and services see !ab(e. 1 for the communities that (ive in it@senvirons. "ecause they have traditiona((y been thought of as (o va(ue/ un'(easant '(aces/mangroves/ in the main/ have not been (egis(ated for but have been o'en to everyone. It astherefore re(ative(y easy for deve(o'ers/ often from far aay/ to turn these high(y 'roductive/com'(e& ecosystems into a sing(e5use 'rivate domains $rimavera/ 1>9>/ "arg/ 1>>2. It hasoften been cited that auacu(tura( deve(o'ments bring em'(oyment/ but it is often the case thatdeve(o'ers have 'referred to bring their on or#force ith them. !hus/ many 'oor 'eo'(e

ho de'end on mangrove forests for their (ive(ihood are eventua((y dis(ocated *ac(auso/1>9>.

)(though the majority of coasta( auacu(ture o'erations to date have had (itt(e adverse effecton ecosystems "arg/ 1>>2/ there have been a great many cases here severe environmenta(degradation has occurred/ as in the case of shrim' farming 'ractices in *outheast )sia andatin )merica e.g. Me(tAoff and i'uma/ 1>97; "ai(ey/ 1>99; +hua $hi((i's et a(./ 1>>?;)i#en/ 1>>?. 3ith greater re(iance on auacu(ture due to over5stressed natura( fisheries/im'rovements in techno(ogy and the conseuent intensification of cu(ture methods/ thehaAards 'osed are increasing.

)(( auacu(ture o'erations im'act on the environment/ but to varying degrees $hi((i's/ 1>>-.Mo((usc and seaeed farming/ for e&am'(e/ occu'y s'ace/ 'ossib(y bringing them intoconf(ict ith fishermen and others navigating inshore aters/ and may restrict ater f(o andaffect sedimentation rates/ but are otherise environmenta((y friend(y )nge((/ 1>97;Macintosh and $hi((i's/ 1>>6. !a#en co((ective(y/ the 'otentia( negative environmenta(im'acts of tro'ica( coasta( auacu(ture can be summariAed as fo((os:

1. de'(etion of natura( resources e.g. fry co((ecting2. c(earance of et(and habitats,. discharge of nutrients and organic astes

-. introduction of e&otic s'ecies6. re(ease of antibiotics and other chemica(s7. increase in 'athogens numbers8. (oering of ater tab(es from ater e&traction9. sa(iniAation of freshater su''(ies>. increase in sedimentation (oads1?. (oering of disso(ved o&ygen (eve(s11. increase in bio(ogica( and chemica( o&ygen demand.

3ith environmenta( ris#s (i#e these/ it is vita( that effective integrated coasta( managementand sound auacu(ture husbandry techniues are em'(oyed. !here are even cases here one

form of tro'ica( coasta( auacu(ture is im'acting on another form; for e&am'(e/ the dec(ine ofcrab farming in *urat !hani/ *outhern !hai(and is b(amed on the deve(o'ment of shrim'


15/29

farms hich have removed (arge areas of the mangrove habitat associated ith this s'ecies'ersona( observation.

Shrim( farming

)(though tro'ica( shrim' farming has a (ong history/ dating bac# at (east -?? years e.g. the@tamba#s@ of Indonesia/ @bheris@ and @gers@ of "enga( and tida( 'onds in %cuador the e&'ansionof the industry over the (ast 16 years has been e&treme(y ra'id and it@s environmenta( im'actis no the subject of grave concern e.g. $rimavera/ 1>9>/ Macintosh L $hi((i's/1>>2.

Modern 'enaeid shrim' cu(ture began in Ba'an over 6? years ago/ ith the deve(o'ment ofsuccessfu( hatchery techniues/ and s'read throughout *outheast )sia and +entra( and *outh)merica. !he ear(y 'roduction (eaders/ !aian and %cuador have no been su'erceded by+hina/ !hai(and/ Indonesia and the $hi(i''ines +savas/ 1>>?. 3ith an estimated 9?G ofcu(tured shrim' being so(d on g(oba( rather than domestic mar#ets this is a va(uab(e source offoreign e&change for deve(o'ing countries. It is not sur'rising therefore/ that there has been a

(arge increase in the number of countries from the Indian subcontinent/ +entra( )merica/*outheast )sia and Oceania hich are no engaged in shrim' farming +savas/ 1>>?; iao/1>>?; 3edner L 3i(dman/ 1>>2. $roduction trends suggest that the e&'onentia( groth

'eriod for shrim' cu(ture that occurred during the (ate 1>9?@s is draing to a c(ose and thate&'ansion (oo#s set to continue/ but at a s(oer rate $hi((i's et a(./ 1>>,.

Most shrim' are cu(tured in 'onds/ a(though some s'ecies have been cu(tured in 'ens andcages "everidge/ 1>9-. )vai(abi(ity and cost of (and is therefore a very im'ortant criterionin site se(ection for 'otentia( investors. Mangroves ere one of the first environments to beconverted into auacu(ture farms as they a((oed tra''ing and ho(ding of i(d shrim' andfish in tida((y f(ushed 'onds. )(though mangrove areas are no genera((y considered to be

sub5o'tima( for the cu(ture of shrim' due to their acid5su('hate soi(s and high c(earance andmaintenance costs (arge tracts of forest are sti(( being converted to shrim' 'onds. !hecontinued use of mangrove areas for shrim' farming is 'robab(y due to severa( reasons: their

'ro&imity to brac#ish ater su''(ies/ being situated on (eve( terrain/ the 'resence oftraditiona( tra''ing and groing grounds/ often hundreds of years o(d +savas/ 1>>?; suchareas have been targeted for rec(amation and deve(o'ment into modern farms; o'tima( (andin the region had a(ready deve(o'ed and 'ro'erty rights to mangrove areas are often chea' andreadi(y avai(ab(e.

In recent years there has been a great dea( of attention given to the im'act of shrim' cu(tureon mangroves $rimavera/ 1>>1/ $hi((i's L Macintosh/ 1>>2. Re(iab(e figures for theconversion of mangrove areas to shrim' 'onds are e&treme(y difficu(t to find but if a(( the>>,/86? ha. of shrim' 'onds ere converted from mangroves then this ou(d on(y accountfor (ess than 7G of the g(oba( resource. In rea(ity the figures are much (oer than this as insome countries such e.g. +hina shrim' 'onds are found (arge(y in non5mangrove areas andin others e.g. the $hi(i''ines many of the traditiona( e&tensive systems have been ino'eration for many years Macintosh and $hi((i's/ 1>>2. !he 'rob(em remains serioushoever; !hai(and has (ost a tota( of 2?,/??? ha/ or 62G of the tota( mangrove resource/ since1>71 )non/ 1>>, a(though the !hai government has at (ast recogniAed the im'ortance of

'reserving it@s 'ristine forests and is no using remote sensing to trac# their (oss and to'rovide a methodo(ogy for a cost5effective/ re(iab(e and effective information gathering

system for sensib(e mangrove '(anning and management. Hoever/ des'ite (egis(ation/ therehas so far been no firm enforcement and the conversion of mangroves to shrim' farmscontinues "riggs/ 1>>-.


16/29

*imi(ar events are ta#ing '(ace in many other areas of the or(d; in Indonesia/ most of the,??/??? ha. of (and being used to cu(ture shrim' as e&5mangrove forest and the governmentis '(anning to raise this figure to more than 1 mi((ion ha. "y 1>96 Bava had (ost 8?G of it@smangroves/ *u(aesi ->G and *umatra ,7G +savas/ 1>99. ) simi(ar scenario e&ists in the$hi(i''ines here mangrove areas have shrun# from --9/??? ha. in 1>79 to 11?/??? ha. in

1>>1. !his destruction has had a devastating effect on coasta( fisheries and has (ed to themargina(isation of subsistence fisherman and the erosion of shore(ines *ingh/ 1>98;$rimavera/ 1>9>;; "arg/ 1>>2; +hua/ 1>>,. )s e(( as removing the economic va(ues of theforest/ the construction of cana(s and di#es irreversib(y a(ters the hydro(ogica( characteristicsof the area and thus the eco(ogy of the system +savas/ 1>>?.

)(though there are many different techniues used to cu(ture shrim'/ they can broad(y be'(aced in three categories:

E'tensive culture

!hese are based on methods that have been 'ractised in )sia for hundreds of years and arecharacteriAed by (o in'uts and (o yie(ds !ab(e 2. 3hi(st these systems are sti(( verycommon in )sia they are gradua((y being su'erceded by more intensive methods $hi((i's eta(./ 1>>,. !he fact that these systems have been uti(ised for such a (ong 'eriod of time atteststo their 'otentia( sustainabi(ity. !raditiona((y/ 'onds ranging in siAe from 1 to severa( hundredhectares *i(as/ 1>98; cited in $hi((i's et a(./ 1>>, are e&cavated in inter5tida( areas and are(arge(y de'endent on the entry of i(d fry into the 'onds during s'ring tide. !hese are thenon5gron using the natura( food of the ater body/ often in combination ith a variety ofother s'ecies e.g. mi(#fish. *ince the occurrence of fry is seasona( and the numbersun'redictab(e/ the 'roduction of shrim' is unre(iab(e. It is therefore im'ossib(e to e&act(y statethe initia( stoc#ing density/ a(though it is genera((y to be be(o 1? m52 ith a yie(d (ess than

6?? #g ha51 yr51. 0nregu(ated stoc#ing by this method a(so a((os 'redators and com'etitorsto enter the 'ond/ further reducing the efficacy of this method.

*u''(ementary stoc#ing ith either i(d5caught or hatchery5reared fry is no more common/hoever/ the former too is becoming (ess re(iab(e as over5fishing and habitat destruction resu(tin (oer numbers of i(d5caught shrim' fry being avai(ab(e. In India for e&am'(e there is aasted @by5catch@ of > #g of young fish and she((fish for every 1 #g of shrim' seed obtained.

It is estimated that 1?? organisms are destroyed for every shrim' fry co((ected to su''(ye&tensive shrim' 'onds @gers@ in "ang(adesh; as many as 9?G of the 'eo'(e in some coasta(areas of the country are engaged in auacu(ture seed co((ection 'ersona( observations.

!he (arge tracts of/ increasing(y e&'ensive/ (and reuired to 'rofitab(y farm using thesemethods are becoming (ess easy to justify. !o convert (arge areas of high(y 'roductivemangrove forest to (arge sathes of fishCshrim' 'onds/ as has occurred in severa( *outheast)sian countries/ notab(y the $hi(i''ines $rimavera/ 1>>-/ ou(d seem to be high(yundesirab(e. One 'ossib(e e&ce'tion to this is the @tamba# tam'ung sari@ system no beingem'(oyed in Indonesia this integrated mangrove5 auacu(ture system is discussed in thesection on integrated mangrove management.

Intensive culture methods

Intensive cu(ture methods for shrim' emerged during the 1>8?@s/ 'ioneered by the !aianeseafter the deve(o'ment of successfu( hatchery techniues for $eneaus monodon. +hua and!ech 1>>? have cited four main reasons for the ra'id increase in intensification:


17/29

1. deve(o'ment of hatchery techniues and the ca'abi(ity of 'roducing (arge amounts of(arva( food

2. formu(ation of artificia( feeds hich enab(ed (arge5sca(e commercia(iAation,. engineering im'rovements and innovations in auacu(ture faci(ities such as 'ond

designs/ 'add(e hee(s/ aerators etc./ boosting the carrying ca'acity of groout and

hatchery faci(ities-. u'grading of technica( s#i((s in farm o'eration and management

3ith the abi(ity to 'roduce seed at i((/ thus ensuring a (arge and re(iab(e su''(y/im'rovements in techno(ogyChusbandry and the ra'id increase in or(d shrim' 'rices/ thetime as ri'e for an increase in the (eve( of intensification. Hoever/ it soon became a''arentthat a(( as not e((. !he intensive shrim' farming industry/ in !aian and (ater in !hai(and/has a(ays been 'rone to over5e&'ansion *hee#s/ 1>9>. One reason for this as that/ des'itethe high initia( investment cost/ the first harvest cou(d be obtained ithin four months and asmany as three cro's cou(d be obtained annua((y. )t first it seemed that (arge 'rofit marginscou(d be rea(ised indefinite(y +hong/ 1>>?. In 1>98/ for e&am'(e/ some !hai shrim' farms

rea(ised 'rofits as high as 1 mi((ion baht 0*K -?/??? from a 1 ha. 'ond in a sing(e cro'.Hoever/ once intensive cu(ture as ado'ted/ (and 'rices rose ra'id(y. !his forced neinvestors into greater intensification in order to 'ay bac# the s'ira((ing investment costs. Highinterest (oans ta#en by many sma(( farmers a(so encouraged ra'id re'ayment and hence/over(oading of the system. !his as further aggravated by the high o'erating costs and strongmar#et com'etition/ unti( there as no sim'(e a(ternative to increasing intensity *hee#s/1>9>.

!he most dramatic crashes thus far have occurred in !aian/ here it has occurred on threese'arate occasions des'ite the (oering of stoc#ing densities and the sitch to disease5resistant s'ecies "riggs/ 1>>-. *hrim' farming a(ong the head of the =u(f of !hai(and meta simi(ar fate hen the industry crashed after just to groout seasons/ ith the region@s

'roduction fa((ing from 8?G to 2? G of the countries@ tota(. In both cases/ the over5e&'(oitation of coasta( resources/ industria( 'o((ution/ im'ro'er site se(ection 'articu(ar(yith regard to ater su''(y and discharge/ 'oor farm design and management 'ractices/over5stoc#ing and se(f5'o((ution/ combined ith the get5rich5uic# menta(ity of shrim'farming s'ecu(ators/ (ed to severe environmenta( degradation. Mc+(e((an/ 1>>1; +hua/ 1>>,;egan/ 1>>,; $hi((i's et a(./ 1>>,. Many of the +entra( !hai farmers have no migratedsouth/ here there is (ess industria( 'o((ution/ higher ua(ity seaater and better direct accessto the sea. Des'ite these advantages/ a 1>>2 Overseas Deve(o'ment )dministration OD)survey re'orted that/ in one region/ after on(y three groout seasons/ 'ond 'roductivity had

fa((en by 2-G on average and that 86G of farms ere e&'eriencing disease 'rob(ems$hi((i's/ un'ub(ished data.

!here is groing evidence that the environmenta( im'acts of shrim' farming '(ay asignificant ro(e in the disease outbrea#s and subseuent cro' (oss/ as a resu(t of over(oadingthe carrying ca'acity of the environment $hi((i's et a(./ 1>>,. !he increasing incidence ofdisease and the environmenta( degradation has (ed to s'ecu(ation over the continuing

'ros'erity/ even the surviva( of marine shrim' farming $ruder/ 1>>2. It is no understoodthat Monodon bacu(ovirus M"/ the vira( disease hich has been b(amed for the crashes ofthe !aianese and +entra( !hai shrim' farming industries/ as e(( as other o''ortunisticdiseases/ inc(uding ibrio s''./ other bacteria and 'rotoAoans/ are not 'articu(ar(y 'athogenic

if shrim' are #e't in o'tima( conditions 4ash/ 1>99; in/ 1>9>; *hee#s/ 1>9>; +savas/ 1>>?.It is therefore the mismanagement of the ecosystem (eading to 'ond conditions stressfu( toshrim'/ hich is the root cause of most shrim' diseases in/ 1>9>.


18/29

Des'ite the fact that !aianese shrim' 'roduction techniues have a(ready been shon to beunsustainab(e/ the short5term financia( success of shrim' 'roduction in !aian and !hai(andhas encouraged other deve(o'ing countries to as# them for he(' in deve(o'ing their onindustries "riggs/ 1>>-. Indeed the !aianese government is no funding a feasibi(ity studyfor a re(ocation 'roject that ou(d encourage !aianese farmers to estab(ish o'erations

abroad/ 'articu(ar(y in atin )merica and other *outheast )sian countries/ thus avoiding high'roduction costs and further environmenta( degradation in !aian )non/ 1>>,. *imi(ar(y/(eading com'anies in !hai(and are strong(y 'romoting shrim' farming in countries such asIndia and ietnam +$ 4es(etter/ 1>>-. !he !aianese government 'resumab(y fee(s that itis better to decimate the coast(ines of other countries for it@s on economic gain. In otherords/ the economic incentives from shrim' farming are sti(( so high that the coasta(resources of these (ess deve(o'ed countries are being '(aced at ris#.

3ith the unrestricted e&'ansion of intensive coasta( shrim' farming have come a mu(titude ofenvironmenta( 'rob(ems. )'art from the destruction of mangrove forests/ they inc(ude thesa(ination of agricu(tura( (and and freshater auifers/ (and subsidence and deteriorating

ater ua(ity due to sediment (oadings and nutrification. !he industry itse(f has becomeconcerned about sustainabi(ity/ as shon by the trend toards (oer shrim' stoc#ing rates tocombat stress and disease in high density shrim' cu(ture $hi((i's et a(/ 1>>,.

Semiintensive culture (ractices

)s the name im'(ies/ these cu(ture 'ractices fa(( somehere in beteen e&tensive andintensive methods of 'roduction. $onds are stoc#ed ith hatchery reared or i(d caught 'ost5(arvae and the farmer re(ies on the natura( 'roductivity of the 'ond a(ong ith su''(ementaryartificia( feeds. )(though at one time thought to be sim'(y an intermediate stage beteen @(otechno(ogy@ e&tensive and @high techno(ogy@ intensive 'ractices/ semi5intensive farming is

regarded by many e&'erts as the on(y (ong5term/ sustainab(e ay to 'roduce shrim'.

%conomic ana(ysis too has shon that hi(e a(( systems from e&tensive to high(y intensive are'rofitab(e hi(st the mar#et va(ue of shrim' remains high/ on(y semi5intensive systems caneasi(y survive a 2?G f(uctuation in in'uts andCor mar#et va(ue +savas/ 1>99/ 1>>?; +hong/1>>?; $rimavera/ 1>>-. Intensive o'erators/ ho have a 'rofit 'er unit area of cu(ture butith a narro 'rofit margin 'er vo(ume and e&tensive o'erators/ ho have (o 'roduction(eve(s/ ou(d be driven into the red under these conditions. 3ith increasing com'etition frommany different areas forcing 'rofit 'er #i(ogram don/ intensive 'roducers i(( be at adisadvantage. *ince semi5intensive cu(ture a(so has (ess environmenta( im'act/ manyresearchers are no strong(y advocating/ a(ong ith im'roved shrim' 'ond management/ a

reduction in the de'endence on intensive systems +savas/ 1>99/ 1>>?; $rimavera/ 1>9>; astL ester/ 1>>2; Macintosh L $hi((i's/ 1>>2.

Unsustainale )/uaculture

3hi(st semi5intensive shrim' farming may be (ess detrimenta( to the environment than othersystems of shrim' 'roduction/ there is sti(( some doubt about its (ong5term sustainabi(ity.!hey sti(( reuire (arge amounts of c(ean/ nutrient5rich ater/ fish and cerea(s in the form of

'e((ets for feed and i(d shrim' fry andCor broodstoc# from hea(thy mangroves 4aamin/1>>1; $a and +hua/ 1>>1 cited in o(#e and Eauts#y/ 1>>-. !he great majority of shrim'farms are through'ut systems/ that is resources are 'um'ed in/ used u'/ and 'um'ed out in a

(inear fashion/ rather than being recyc(ed. !he resu(t of this is accumu(ation of astes in thesurrounding ecosystems hich can (ead to severe and sometimes irreversib(e 'rob(ems. !hecontinuing high resource demands of such systems ma#es them unsustainab(e in the (ong5


19/29

term. )(though it may not be immediate(y a''arent/ through'ut systems de'end entire(y on aresource base hich direct(y or indirect(y/ is (in#ed to the very ecosystems that they degrade.!he fai(ure of through'ut systems to recogniAe and res'ond to these (in#ages ma#es theminherent(y unstab(e and (i#e(y to co((a'se/ as the degradation of their su''ort systems remainsunnoticed o(#e and Eauts#y/ 1>>-.

o(#e and Eauts#y 1>>- have made an attem't to uantify the s'atia( ecosystem su''ort/ oreco(ogica( foot'rint/ that is reuired to sustain semi5intensive shrim' farms on the +aribbeancoast of +o(umbia. !hey did this by estimating the fo((oing:

1. sea surface area and agricu(tura( area reuired to sustain the euiva(ent yie(d offishmea( and cerea( in feed 'e((ets needed for a 1 ha. shrim' 'ond

2. mangrove 'ost5(arva( area reuired to 'roduce sufficient amounts of shrim' 'ost5(arvae; the mangrove su''ort area necessary to 'roduce (itterfa((Cdetritus that asassumed to contribute ,?G to the shrim's@ diet

,. e&tent of the su''ort system necessary to 'rovide ater for the 'onds and to receive

their discharge-. ecosystem area needed to seuester the carbon dio&ide re(eased by industria( energy

in'uts both direct(y and indirect(y.

rom these ca(cu(ations they suggest that a semi5intensive shrim' farm reuires a s'atia(ecosystem su''ort system/ or eco(ogica( foot'rint/ that is ,651>? times as (arge as the surfacearea of the farm. +(ear(y/ this is far greater than the re(ative amount of mangrove and othersu''ort areas that have been (eft in most major shrim' farming regions.

!he high(y intensive nature of the through'ut system as is no common in shrim' farming ison(y 'ossib(e because of the high mar#et va(ue of of the 'roduct. Hoever it is c(ear thatsocio5economic factors must be ta#en into account hen assessing the benefits of intensiveshrim' auacu(ture o'erations. !he deve(o'ment of sustainab(e shrim' farming i(( reuirethat the rea( 'rice of shrim' 'roduction/ inc(uding those of im'airment/ degradation anddestruction of the ecosystem and environment be ta#en into serious consideration +hong/1>>?. !hese are costs that never a''ear on any farm (edger and hich are difficu(t toestimate/ but hich are essentia( in gauging the fu(( im'act of these 'roduction systems"riggs/ 1>>-. If the va(ue to society of the (ife5su''orting environment is not recogniAed/there is a severe ris# that a short 'eriod of 'ros'erous groth of the auacu(ture industry/ dueto intensive ecosystem e&'(oitation/ i(( turn into severe eco(ogica(/ economic and socia(

'rob(ems/ that counteracts the 'ossibi(ity for sustainab(e deve(o'ment o(#e and Eauts#y/

1>>-b !here is/ hoever/ a (arge 'otentia( for recyc(ing of resources and reduction of asteand 'o((utants.

Other )/uaculture

,ater /uality (rocesses in shrim( (onds and identified (rolems

!he maintenance of a (o stress rearing environment reuires good 'ond ater ua(ity. Inintensive farms the high stoc#ing densities invo(ved reuire high (eve(s of a''(ied feedresu(ting in a need for the ra'id remova( of aste 'roducts/ chief(y dead '(an#ton from the

'ond b(oom and nitrogen and 'hos'horus from unassimi(ated feed. If this is not achievedthe ater ua(ity of the 'ond i(( deteriorate causing stress to the shrim' and a corres'ondingsusce'tibi(ity to disease in/ 1>9>; +hua et a(./1>9>; +hien/ 1>>2. !here are severa( aterua(ity 'arameters hich affect shrim' 'roduction :


20/29

In *outh )merica/ auacu(tura(ists have genera((y 'referred sa(t f(ats and in(and areas for theconstruction of 'onds because of the (oer (and 're'aration and 'ond construction costs*neda#er et a(. 1>97. Hoever/ the e&treme(y ra'id deve(o'ment of the industry has (ed toshortages of more suitab(e sites and (arge areas of mangroves have been converted toauacu(ture. $rior to 1>9?/ on(y %cuador had a siAeab(e area devoted to shrim' auacu(ture/

but ins'ired by 'erceived financia( success/ other +entra( and *outh )merican countries areencouraging simi(ar auacu(ture deve(o'ment ibid..

*idda(( et a(. 1> uote 2/2?? ha as the area being a((ocated converted to shrim' farmingun(icensed o'erators/ hich are more freuent(y in mangroves/ may not be fu((y inc(uded inthis figure. )''ro&imate(y 6G of $anama@s mangrove have been converted to shrim' 'ondsibid.. )''ro&. 26G of mangroves have been converted to 'onds in %cuador *idda(( et a(.1>.

In Me&ico shrim' maricu(ture is active(y reserved for coo's and not 'rivate farms. %&tensiveshrim' maricu(ture methods by c(osing off (agoons i(( therefore continue as the dominant

'roduction system.

In $anama/ shrim' maricu(ture had a re(ative(y sma(( im'act on mangroves because semi5intensive rather than e&tensive systems/ c(ear administrative frameor#/ and goodinformation for management 'ur'oses. )uthorities have co5o'erated to steer investors aayfrom mangrove to sa(t f(ats by 'ub(ishing costs of construction in m. areas and ris#s from acidsu('hate soi(s. *uitab(e sa(t f(at areas avai(. '(us semi5intensive nature/ '(us 'resence ofRa(ston5$urina set e&am'(e.

*hrim' cu(ture has yet to become estab(ished in any )frican nation '.->/ a(though others'ecies are 'roduced most(y finfish for domestic consum'tion using earthen 'onds/ or brush

'ar#s or fish cages in (agoons +oche 1>92. )rdi(( 1>92 re'orted 're(iminary '(anning forshrim' 'ond construction in Madagascar 2??ha and Eenya 6?ha and entre'reneurs haveshon strong recent interest in starting (arge shrim' farms in these countries; efforts have a(so

been made to start commercia( shrim' farming in the =ambia using im'orted b(ac# tigershrim' 'ersona( observations. !he Ivory +oast/ "enin/ =hana/ and 4igeria are other 'arts of)frica considered 'hysica((y suited to shrim' maricu(ture.

Integrated Systems of Mangrove Management

Smallscale Systems

or economic reasons integrated systems usua((y see# to combine the sustainabi(ity ofmangrove forest conservation/ or rotationa( forest management systems/ ith the high income

'otentia( from mangrove fisheries or auacu(ture. One traditiona( form of this conce't are the@tamba#s@ in Indonesia 5 e&tensive 'onds for tra''ing and ho(ding fish and she((fish/ herestri's of mangrove forest are retained on higher ground ithin the 'onds and trees are '(antedaround the dy#es to 'rovide soi( stabi(ity/ shade and a source of organic enrichment via (eafdetritus to the 'onds. Origina((y these tamba#s ere created in northern Bava for mi(#fish/ith shrim' and crabs tra''ed as a secondary cro' described by *chuster/ 1>. !amba#s areno found throughout Indonesia and they are 'rinci'a((y s'ecia(ised for shrim' farming/es'ecia((y in *u(aesi. Hoever because of over e&'ansion of tamba#s/ and other forms of

coasta( habitat deve(o'ment/ the re(ative areas of mangroves to 'onds has dec(ined to a 'ointhere their natura( 'roductivity is e&treme(y (o. *ince the (oss of mangrove resources a(soaffects their function as nursery sites for juveni(e fish and she((fish/ i(d shrim' fry are no


21/29

much rarer/ ma#ing it necessary for tamba# o'erators to sitch toards hatchery 'roduced'ost (arvae. !he (atter are genera((y regarded as being @ea#er@ than i(d fry and conseuent(ysurviva( rates and 'roduction are often 'oor *u(aesi/ 'ersona( observation.

In Indonesia a modern deve(o'ment from the tamba# conce't is @tamba# tum'ang sari@ or

@'ond forest@ described by *u#ardjo/ 1>>N. !his integrated system deve(o'ed on the northerncoast of est Bava in the 1>9?s as a res'onse to the 'rob(ems of (ac# of income o''ortunitiesfor 'oor coasta( communities. Due to coasta( erosion caused by mangrove degradation/ the*tate orestry +or'oration undertoo# reforestation using RhiAo'hora s'ecies. "ehind the

'rotective mangrove Aone/ bunded fish'onds ere constructed ith mangrove trees '(anted asseed(ings in the e(evated the centra( 'art ig. 2. ) main cana( ith a ater gate a((oedater e&change in the 'ond; the 'ond itse(f had a s(uice gate and fish ditches around andacross the 'ond bottom to create a good environment for auacu(ture.

In the first 'hase of im'(ementation , to 6 years this system o'erated as a conventiona('ond; it as enriched by adding mangroves (eaves as a manure. ish and shrim' entered via

the su''(y cana(/ then cou(d be harvested virtua((y on a dai(y basis in sma(( uantities once the'ond biomass had bui(t u'. "y the second 'hase 6 to 1? years groth of the centra(mangrove had created a forest of sa'(ings or sma(( trees about 6 m ta((. )t this 'oint the orest+or'oration cou(d begin some e&'(oitation of the mangrove resource as the s'ecies '(antedRhiAo'hora has high economic va(ue for fue(ood and 'o(es.

It shou(d be noted that under this modern Indonesian system/ the (oca( 'eo'(e did not on the(and or fish'onds/ but ere sim'(y em'(oyed by the government agency to underta#e themangrove '(anting. !his generated the euiva(ent of -??? man days of or# for each hectareof tum'ang sari deve(o'ed *u#ardjo/ 1>>N. "y inc(uding the auacu(ture com'onent/ (oca(

'oor 'eo'(e a(so benefited from a significant income from auatic 'roducts for ,56 years unti(the forest had deve(o'ed. "y this 'oint conditions in the 'ond for auacu(ture had dec(ined

because of croding by the trees and an increase in fish 'redators e.g. birds and otters and'est s'ecies.

)(though im'rovements to the management of the system are reuired in order to increase the(onger term benefits from mangrove fisheries/ the conce't is be(ieved to be sound and a

'ossib(e mode( for ider ado'tion in Indonesia *u#ardjo and !oro/ 1>98. More rea(istica((y/it 'rovides tem'orary em'(oyment and income for some (oca( 'eo'(e/ and for the orestry+or'oration an efficient means of reforesting degraded coasta( mangroves/ but it does notcreate community onershi' and management of the resource. )fter five years the fishermen

cannot buy the fish'onds and the mangrove forest is the 'ro'erty of the orestry+or'oration/ a(though some im'rovement in coasta( fish catches may be e&'ected.

!he integration of mangrove forestry ith auacu(ture is a(so being tried in ietnam andMa(aysia using crab rearing as the 'rinci'a( income generating activity. In this case thenatura( mangrove to'ogra'hy is retained by sim'(y fencing off a sma(( area of forest to createa @crab 'en@. !he centra( mangrove area 'rovides a natura( habitat for *cy((a serrata hich are

bought from traditiona( fishermen/ stoc#ed in the 'ens/ and fed trash fish. In *ematan/*araa# a sma(( number of fishermen oners are o'erating crab 'ens successfu((y in this ay'ersona( observation. )(though it is too ear(y to state hat the (ong term sustainabi(ity i((

be/ the economic returns are good after si& or seven months in the 'onds the crabs are

e&'orted to *inga'ore. !he method is certain(y more integrated than conventiona( crab'onds/ since there is the minimum of disru'tion to the mangrove forest or soi( to'ogra'hy."ecause the fences are ooden mangrove sa'(ings or bamboo/ there is a natura( tida(


22/29

e&change through the 'ens. *ome thinning of the centra( mangrove to e&tract 'o(es andfireood and re'(anting ith seed(ings cou(d be deve(o'ed in this ty'e of forestry5auacu(ture system.

0argescale Systems

!here are fe e&am'(es of (arge5sca(e mangrove forestry5fisheries management systems/ butsevera( tro'ica( countries are attem'ting to introduce the conce't of @Aoning@/ hereby areas ofmangrove forest are conserved to 'rovide buffer Aones for coasta( 'rotection and fisheriessu''ort/ hi(e forest e&'(oitation/ auacu(ture deve(o'ment/ or other economic activities/ are

being confined to the inner mangrove Aone and to coasta( (and above the intertida( Aone.

In !hai(and/ for e&am'(e/ the 'rob(ems of 'oor coasta( ater ua(ity associated ith asteaccumu(ation from intensive shrim' farms has 'rom'ted a ban on shrim' farm deve(o'menton mangrove (and. Instead/ shrim' farmers are being encouraged to construct 'onds behindthe mangrove Aone so that the (atter can serve as a natura( bio(ogica( fi(ter to im'rove ater

ua(ity before it reaches the 'onds. In the (argest mangrove area in !hai(and/ the Ranongecosystem/ areas of concession forest aarded to charcoa( 'roducers are gradua((y beingta#en bac# under the direct contro( of the Roya( !hai orest De'artment. !he mangroves i((then be managed as conservation forest in recognition of their greater va(ue to fisheries andcoasta( 'rotection. It is a(so of benefit to the many shrim' farms hich are being bui(t in (andimmediate(y behind this e&tensive mangrove de(ta. *ince Ranong is the ettest region of!hai(and Macintosh et a(/ 1>>1/ 'articu(ar im'ortance is attached to the va(ue of themangroves to tra' sediments and reduce erosion.

*onservation and Resource Enhancement

%rotection of #iodiversity

*aenger et a(. 1>9, 'rovide a summary of the ty'es of reserves/ inc(uding mangroves/designated by different countries. !raditiona((y/ mangroves and other tro'ica( et(ands havenot been considered 'articu(ar(y rich in s'ecies/ es'ecia((y in com'arison to the e&treme(yhigh biodiversity found in cora( reefs and rainforests. In conservation terms hoever/ thisvie is counter5ba(anced by the e&treme(y high abundance and 'roductivity of certain et(and

'(ant and anima( s'ecies. !hese characteristics of mangroves ma#e them im'ortant for otheri(d(ife/ s'ecifica((y:5

1. as dry season refugia and subseuent(y as sources for re5co(onisation of surroundinghabitats/

2. as feeding grounds for resident and migrant i(d(ife/,. as breeding and nursery grounds/-. as a (in# beteen terrestria( and marine ecosystems.

!he abundance of i(d(ife 'robab(y attracted ear(y natura( history enthusiasts and hunters tothe estuaries/ is(ands and (agoons habitua((y used by nesting and over5intering aterfo(.+onseuent(y/ the significance of mangroves and associated habitats is much bettera''reciated for birds than any other grou' of i(d(ife/ and a number of conservationinitiatives have focused on their 'rotection. In Indonesia/ endangered s'ecies associated ith

mangroves inc(ude the mi(#y stor# and (ess adjutant stor#/ hi(e mangrove mudf(ats serve asfeeding areas for huge numbers of migratory aterbirds/ inc(uding rare s'ecies *i(vius/


23/29

1>98. In Mauritania/ the tida( f(ats of the "anc d@)rguin 4ationa( $ar# 'rovide a interingsite for some , mi((ion shorebirds every year I0+4 1>>?.

It is more recent research that has high(ighted the other s'ecies of conservation concern forhich mangroves are an im'ortant ecosystem. Moreover/ as research has continued/

e&amination of the (arge range of niches avai(ab(e for use a three dimensiona( s'ace in theterrestria( rea(m (i#e a norma( forest/ and a three dimensiona( in an auatic one/ (in#ed by ahigh(y dynamic inter5tida( Aone/ has revea(ed greater biodiversity than as origina((ye&'ected. o'eA et a(. 1>99 'rovide a summary of references giving (ists of invertebrates'ecies associated ith mangroves and benthic habitats adjacent to mangroves.

ieed in iso(ation/ the mangrove itse(f is sti(( of on(y moderate significance/ but it assumesfar great im'ortance hen its fundamenta( eco(ogica( (in#ages ith other habitats are ta#eninto account. !hus a great number and variety of birds/ mamma(s/ fish and invertebratesuti(ise mangroves during at (east one 'art of their (ife cyc(e.

!hose s'ecies of greatest conservation concern that are associated ith mangroves have beenrevieed by *aenger et a(. 1>9,. Of 21 crocodi(e s'ecies recognised by +I!%*/ seven areendangered and of these/ NNN inhabit mangrove dominated environments. or e&am'(e/*i(vius 1>98 mentions that conversion of riverine mangroves in Indonesia i(( furtherreduce the habitat avai(ab(e to three a(ready endangered s'ecies in Indonesia: +rocodi(us

'orosus/ +. novaeguineae and !omistoma sche(ege(ii.

arge mamma(s are es'ecia((y vu(nerab(e to human intervention because of their need for(arge forest ranges and their va(ue to 'oachers. In 3est )frica/ the +aribbean/ southern 0*)and northern atin )merica/ manatees have been brought c(ose to e&tinction in many areas byhunting and other disturbance I0+4 1>>?. Fuiet tida( cree#s here overhanging 'ro' rootsgive 'roduction from 'redators/ are thought to be es'ecia((y im'ortant for ca(ving and nurseryareas for these creatures.

In !hai(and the (eaf mon#ey/ $resbytis cristata and in Ma(aysia and Indonesia/ the 'roboscismon#ey 4asa(is (arvatus/ are both vu(nerab(e s'ecies hich inhabit mangroves I0+4 1>>?/hi(e the Ma(ayan sun bear and the ta'ir are simi(ar(y threatened by forest destruction*i(vius/ 1>98.

In India and "ang(adesh/ the re(ative iso(ation of the *underbans mangroves have made themthe (argest remaining habitat of the "enga( tiger $anthera tigris I0+4. Hoever human

'o'u(ation 'ressure is 'erha's the greatest threat to conservation of mangrove i(d(ife seedemogra'hic 'redictions/ section 7.6. Major internationa( efforts have contributed to someconservation success ith the "enga( tiger/ but habitat degradation in the *underbans is as(o timebomb/ hich u(timate(y i(( be just as (etha( for the tiger as the hunter@s bu((et.ourteen s'ecies of mamma( have a(ready disa''eared from "ang(adesh in the 'ast 2?526years 4uruAAaman/ 1>>,.

Recreation and Ecotourism

)t first sight/ the sco'e for recreationa( use of mangrove ecosystems may a''ear to be(imited/ but it is in fact an im'ortant as'ect of the management of mangroves in )ustra(ia

boating and recreationa( ang(ing. !here are a(so some deve(o'ing country e&am'(es. In!hai(and there is considerab(e va(ue attached to the mangroves in $hangna "ay as acom'onent of the bay@s environment hich tourists from $hu#et can visit in '(easure boats. In


24/29

some of the +aribbean is(ands/ fringing mangroves are regarded as im'ortant indirect(y totourism as they act as sediment tra's/ thereby 'rotecting the adjacent cora( reefs from si(tation5 the tourist economy of these is(ands being strong(y de'endent on the attractiveness of theirreef environments.

It is a(so 'robab(e that mangroves i(( feature in future as one of the tro'ica( environmentsattractive to the groing deve(o'ments in ecotourism. "oat tri's through mangroveecosystems are easy to organise and e(evated a(#ays can be bui(t for easy access to theforest environment. 3a(#ays constructed by the Roya( !hai orest De'artment in a forestreserve area ithin the Ranong mangrove ecosystem have 'roved to be high(y successfu( forresearch and educationa( activities invo(ving (arge grou's of 'eo'(e Macintosh/ et a(/ 1>>2.In suitab(e areas/ this conce't is readi(y ada'tab(e to ma#e it attractive to a ider audiencethrough ecotourism; conseuent(y the (atter shou(d be inc(uded as 'art of coasta( Aone

'(anning here it is considered to have 'otentia(. Hoever/ ecotourism must be c(ear(ydistinguished from tourism in its genera( conte&t/ the (atter having had a history usua((yassociated ith negative im'acts on mangroves.

Mangrove )fforestation

Mangroves are one of the easiest tro'ica( forest ty'es to generate because of theirre'roductive bio(ogy and ada'tations to intertida( conditions revieed by !om(inson 1>.!he s'ecies of most economic im'ortance RhiAo'hora and "ruguiera 'roduce vivi'arouss'ear5(i#e seeds hich can be co((ected as 'ro'agu(es the first stage seed(ing from mothertrees and '(anted direct(y into soft coasta( sediments for afforestation 'ur'oses. *eed(ings ofother mangroves/ such as )vicennia and *onneratia/ hich inc(ude more 'ioneer s'ecies thatcan serve a va(uab(e coasta( 'rotection function/ are easi(y reared from seeds in nurseriesdescribed by *iddii et a(/ 1>>,.

)fforestation has un(imited sco'e to increase the mangrove resource base/ 'rotect fragi(etro'ica( coast(ines and 'erha's a(so to enhance biodiversity and fisheries 'roductivity.Mangrove afforestation is 'roceeding on a (arge sca(e in "ang(adesh and ietnam 'rinci'a((yto 'rovide coasta( 'rotection in ty'hoon5'rone areas/ but a(so to acce(erate the rate ofrec(amation of coasta( (and created by natura( accretion/ and to generate economic benefits to

'oor coasta( communities )O/ 1>92; *iddii and Ehan/ 1>>?; *+/ 1>>2; Hong and *an/1>>,.

Mangrove afforestation started in "ang(adesh in 1>77 and by 1>>? '(antations covering

12?/??? ha ere estab(ished; >?G of this tota( as '(anted ith *onneratia and )vicennias'ecies *iddiui et a(/ 1>>,/ ref(ecting the success of these mangrove ty'es as 'ioneers'ecies. Hoever most of the economic mangrove tree s'ecies in "ang(adesh have beentested as '(antations on ne(y accreted (and/ inc(uding Heritiera fomes the most im'ortanttimber tree in the *underbans '(us s'ecies of "ruguiera/ y(ocar'us and %&coecaria *iddiiand Ehan/ 1>>?. In time/ it is antici'ated that as the 'ioneer mangrove dies off/ secondary

'(anting ith these more economic s'ecies i(( be necessary.

In centra( and northern ietnam ty'hoons are virtua((y an annua( occurrence hich havenecessitated the construction of a major coasta( seady#e system to 'rotect agricu(tura( (andand homesteads from storm damage and f(ooding. Hoever/ the seady#es/ hich are of earth/

or earth and stone/ construction/ are easi(y damaged by storms/ or overto''ed by tida( aves;(oss of (ife and 'ro'erty and sa(tater destruction of cro's have been regu(ar occurrences*+/ 1>>2.


25/29

+uture Trends and %olicy &evelo(ment

or the foreseeab(e future/ coasta( Aones i(( come under increasing 'ressure to sustain'o'u(ation groth and the e&'ansion and diversification of nationa( economies. !here is amajor cha((enge to meet in im'roving the management of coasta( areas to accommodate this

groth "urbridge 1>>,.

Ma((ing and Resource )nalysis

Remote sensing and =eogra'hica( Information *ystems have both gone through majortechno(ogica( deve(o'ments during the 1>9?s and are destined to become increasing(yim'ortant in'uts into I+2/ *iri'ong et a(./ 3oodfine 1>>,/ *usanto et a(. 1>96. $rob(emsobtaining c(oud5free cover sti(( occur Macintosh et a(. 1>>1/ s'urring investigations into thesco'e of radar for forest and other ma''ing or#. *ignificant achievements have nonethe(ess

been made in mangrove ma''ing/ as e(( as other I+>,/ sus'ended sediment mode((ing Bensen et a(.1>9> and f(ood ris# "(asco et a(. 1>9>.

I+>1. More so'histicated sectoria( or bi5sectoria( a''(ications a(so no e&ist/ but many are sti(( being tested and revised "o& on)uacu(ture *ite *e(ection.

ina((y/ it is im'ortant if rather obvious/ to stress that the use of these techno(ogies does notitse(f/ guarantee better resource assessment. Measures to ensure high data ua(ity/ ana(ytica(rigour/ hardare maintenance and good organiAationa( management are a(( necessary if I+


26/29

natura( coasta( 'rocesses to achieve @sustainabi(ity@ ithin set socio5economic conditions andecosystem carrying ca'acity. Hoever in most tro'ica( countries there are sti(( significantinstitutiona( barriers to integrated environmenta( management because of the sectora( divisionof res'onsibi(ities beteen government agencies. )deuate environmenta( (egis(ation is/ inmost cases/ either (ac#ing or 'oor(y im'(emented and 'atro((ed. !he objectives of +


27/29

the or# of *+ as 'ub(icised on te(evision and in nes'a'ers by the District)dministration/ giving the 'roject a significant im'act beyond its target grou'.%nvironmenta((y focused coasta( resource management 'rojects/ ith strong community

'artici'ation/ are (i#e(y to be more strong(y su''orted in the future.

&emogra(hic Trends

Settlement and Industrialisation

!he coasta( Aone has become the foci for 'o'u(ation and economic activities of many nations"urbridge/ 1>>,. +urrent(y/ estimates suggest that 6?58?G of the 3or(d@s 6., bi((ion

'o'u(ation (ive in the coasta( Aone Ibid/ and this 'ro'ortion is increasing. rom 1>9? to2???/ estimates suggest that coasta( urban 'o'u(ation i(( increase by ,9? mi((ion 3RI1>>,. "y 2?2?/ 04+%D )genda 21 re'ort that u' to 86G of the or(d 'o'u(ation cou(d be(iving ithin 7?#m of the shore and that the 3or(d@s 'o'u(ation at that 'oint i(( be around 9

bi((ion.

!a#ing account of differences in 'o'u(ation structure of industria(ised and (ess industria(isedcountries/ a''ro&imate(y >6G of this future 'o'u(ation groth i(( occur in the (atter Enechtet a(. 1>>,.

!he 'o'u(ation of coasta( areas and their groth rates do vary ide(y beteen nations!ab(e / ith differing historic inf(uences affecting sett(ement 'atterns. $rojected

'o'u(ations for various countries are shon in igure .

Reasons for *oncentrated Settlement

!he needs to be (ocated in coasta( or estuarine sites for access to sea or river trading routeshistorica((y has been a major inf(uence in creating coasta( sett(ements. +oasta( ecosystems/

being some of the most 'roductive/ have a(so attracted 'eo'(e to e&'(oit them/ and in addition/the coast@s abi(ity to su''ort many different uses has encouraged a ide range ofdeve(o'ment. !he occurrence of high ua(ity soi(s ith favourab(e s(o'es ithin the (oerreaches of atersheds has been a further factor. +o(onia(isation a(so has had a mar#ed affect/either enhancing e&isting coasta( sett(ement 'atterns/ or estab(ishing ne ones often re5(ocating or im'orting 'o'u(ations simu(taneous(y to faci(itate the e&'(oitation and e&'ort ofra materia(s. ootn

10700 Mangrove Ecosystems

Documents

Transcript of 10700 Mangrove Ecosystems