Fauna Deep Sea
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Transcript of Fauna Deep Sea
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1Deep--Sea Fauna,Zonation and Biogeography
Who Lives in the Deep Sea?Bacteria/ArchaeaProtozoa Meiofauna (42-500 m)Macrofauna (>300 m)Megafauna (visible, >1 cm)Giants
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2Bacteria
heterotrophic,autotrophic
aerobic anaerobic
sulfate reducersulfide oxidizermethane oxidizerFe, Mn oxidizers
in sedimentin gutson detrituson carcassesas symbiontson hard surfaces
BACTERIA AND ARCHAEA
Protozoa
ForaminiferaKomokiacea (superfamily)
Xenophyophores
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3MetazoanMeiofauna
Nematodes Ostracods
Harpacticoid copepods
Gnathostomulida
Kinorhynchs
Oligochaetes
Loricifera
MacrofaunaPeracarid crustaceans
Brachiopoda
Bryozoa
Mollusca
Annelida:polychaetes Priapulida
Amphipods, isopods tanaids, cumaceans
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4Megafauna - Echinoderms
Asteroids
Crinoids
Ophiuroids
Holothurians
Echinoids
Megafauna
Cnidarians
Mollusca
Annelida
Sponges
HagfishEnteropneust
Crustaceans
Echiura
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5Humongofauna (Giants)giant squid
Munopsis
Kinetoskias
Colossendeis
Culeolus
Eurythenes
pycnogonids
ascidians
bryozoan
Site Depth (m) Substrate % Polychaetes Dominant
N. Carolina Margin I. 850 34% sand 43 ScalibregmaNC II. 20% sand 74 ChrysopetalidNC III. 31% sand 66 DorvilleidHorizon Guyot 1840 Foram Sand 47 ParaonidSanta Catalina Basin 1130 Mud 77 ParaonidCentral Pacific Seamounts 1480-3150 Calcareous muds 66-67 CirratulidSan Diego Trough 1230 Mud 76Rockall Trough 2200 ? 59HEBBLE 4820 90% mud 67 AmpharetidPorcupine Abyssal Plain >4500 35 Spionidae Central North Pacific 5500 Red Clay 55Aleutian Trench 7298 49
Polychaetes often comprise half or more of the macrofauna
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6Key Zoogeographic FeaturesOriginal view - 1 province, cosmopolitan species
(no geographic boundaries)
Ekman 1953 - 4 zoogeographic zones:Atlantic, Indo-Pacific, Arctic, Antarctic.
Vinogradova - 1959, 62, 79. Species have limited distributionsOnly 15% of species occur in > 1 oceanOnly 4% of species occur in all ocean
Genetic methods reveal cryptic species; cosmopolitanism rare(France & Kocher 1996) Eurythenes gryllus is many species
But there is great similarity among oceans at the generic level.Genera are cosmopolitan
Of 143 isopod genera in the Pacific , 134 are present in the Atlantic
Desmosomatidae (Isopods): North vs South Atlantic - same 12 generaNorth Pacfic vs Atlantic - Pacific is missing 2 genera and=77% similarity has one not in the Atlantic
Asellote isopodsPoore et al. 94 - 67% of 98 genera on the SE Australian slope arein the Atlantic
Ophiomusium (brittle star) worldwide at mid to slope depths.
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7Vinogradova, 1979. Zoogeographic divisions of the
abyssal and hadal zones of the world
Distinct hadal fauna (Belyaev 1959, 1989)more amphipods, polychaetes, bivalves, echiurids, holothurians
Origins of Deep-Sea FaunaAntarctic or shallow water origins thensubmergence
Deep origins and Antarctic emergence(Ilyarachnid isopods) in taxa withdiversity centers in the deep sea.
Isolated basins have endemics only atspecies level, suggestinginvasion from shelves and recentevolution.
Red Sea and Sea of Japan haveeurybathic species from Indian& Pacific oceans.
A. High latB. EquatorC. Mid lat
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8What is Zonation?Pattern of uniform change in species
Step-like boundaries between regions ofhomogeneous composition.
Current usageNon-repeating, sequential pattern of species replacement
measurable as changes in the overall rate of changein faunal composition.
Why should we care about zonation?Resource exploitation is increasing (fisheries, petroleum)
Sound management demands understanding of distributions
Zonation Terminology
Shelf
Upper Slope
Lower Slope
Continental Rise
Abysssal
meters200
500
1000
3000
4000
6000
Epipelagic (euphotic)
Mesopelagic (disphotic)
Bathypelagic (aphotic)
Benthopelagic
Bathyal
Hadal
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9Zonation in the PastSince Challenger Expedition:
Scientists have recognized that species change much more rapidly with depth down the continental margin than horizontally.
Depth-related changes in the ocean are considered one of the greatest environmental gradients on this planet (Gage and Tyler ).
What can generate zonation in the Ocean?
What can generate zonation in the Ocean?
TemperatureSalinity
Bottom typeFood levels
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Challenger/Sars expeditionsMurray and Hjort (1912)
3 ZONES:
Shelf (to 200/300 m)
Archibenthic transition (600/800 - 2000/3000) (bathyal)(based on megafauna, topography, temperature)
Abyss(upper boundary set at 4oC isotherm - Bruun 1957)(lower boundary at 6000 m - topography)
There is little areabetween 1000 & 2500 m
Yet, this is the zone of highest diversity
shelf
transition
abyss
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Controlling Gradients: LightLight: present to 1000 mChildress 1995: the use of vision by fishes, crustaceans, squidabove 1000 m elevates metabolic rate and affects forms present
Controlling Gradients: Hydrostatic pressureonly variable directly related to depth (10 m = 1 atm)
pressure accelerates reactions in which the molar volumeof the products are less than the molar volumes of thereactants.
Pressure retards reactions in which there is a volumeexpansion (Le Chatelier effect)
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Increased dissolution of calcium carbonateIncreasing metabolic cost associated with maintainingcarbonate structures at depth (molluscs,foraminiferans, echinoderms show effects)Influence on chemosynthesis based on H2S? Stabilityof gas hydrates (>450 m)Protein structure, membrane fluidity, lipid contentDifferent propreties of gellatinous/membranousmegafauna?
A piezo barrier to downward colonization: 500-1000m, 2000-3000m
Effects of pressure in the deep sea
Controlling Gradients: Temperature55oN to 55oS - Warm, low density upper layerThermocline may form a barrier. Much of the deep sea is 2-4oC
Increasing temperature increases chemical reaction rates.2 to 3 x rate increase with 10o C temperature increase.
Adaptations to cold: increasing concentrations of enzymes adopting enzymes effective at low temperatures incorporating modulator compounds that help maintain
enzyme reactions over a range of temperatures
Are water mass effects the result of temperature (?)
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Controlling Gradients: Organic FluxSince Forbes (1859) - importance of food recognized.Decreasing food input with depthDifferent rates of mixing within sediment with depth
Food effects on zonation may be modified by competitors.Effects of OM flux include changes in sediment geochemistry.
High flux depletes oxygen. .
TROX model -
foraminifera distributions based on oxygen and food
TROX model-applied toforaminifera
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Controlling Gradients: Oxygen
Oxygen minima at 100-1000 m (
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Pelagic Zonation
Governed largely by light but in some places temperature.
Evidence of the importance of competition comes from non-overlapping distributions of related species
Ontogenetic zonation is commonOften larvae are found shallowest and gravid females deepest(Tradeoffs between food and mortality from predation)
Zonation may be forced by physiographyof the ocean floor
SHELF BREAK - Boundary between shelf and deep-sea fauna.Referred to as the mud line by John Murray (1895) = upper limit for muddy bottom, deep-sea conditionsmay occur at 200 m (W. Europe), 500 m ( Antarctic)or few m (fjords)
HEMIPELAGIC VS PELAGIC SEDIMENTS Ekman (1953)Break between hemipelagic (with considerable terrigenous input)and pelagic sediments is a key zoogeographic boundary.
ANTARCTIC - Little difference between shelf and deep-sea faunas
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Bathyal (200-3000 m) vsAbyssal (4000 - 6000 m)
Bathyal has shallow and deep faunasAbyssal with true deep faunas.
But new data by Rex for molluscs suggests that most abyssal species also occur in the bathyal realm and few are endemic. (Rex et al. 2005; Am. Nat. 165).
Menzies:Greater continuity of shelf and bathyal faunas at high latitudes and of bathyal and abyssal faunas at low latitudes. Why?
Means of Evaluating ZonationMultivariate Classification Procedures - rely on similarity matrices
similarity coefficients: Percent Similarity Coefficient, Bray Curtis coefficient, Normalized Expected Species Shared [NESS]
Cluster Analysis -highly dependent on parameters chosen(can achieve multiple forms of clustering with same data set)
Ordination - employs linear models, best when only a smallpart of the depth gradient is being examine.
Vertical ranges of species zonal breaks are thosewhere greater number of upper and lower depth limits occur(requires large data set)
Cumulative species curves
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Porcupine Seabightzonalbreaksarethosewheregreaternumberofupperandlowerdepthlimitsoccur
Cascadia Basin
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What Changes with Depth? Taxonomic composition Diversity Density, Biomass Body Size Trophic structure
Megafauna - New England Margin(Hecker 1990- Photographic survey)
(284,692 indiv. 94,380 m2 of seafloor)
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Upper slope: to 700 m Dasmosmilia lymani, Flabellum alabastrum Upper-middle slope: (1100-1200 m)Geryon quinqueidens, SynaphobranchusNezumia, Phycis chesteri, Glyptocephalus
Transitional Lower Middle Slope: 1500-1700Distichoptilum gracile + Anemones
Lower Slope: Ophiomusium lymani, Cerianthid anemone,Distocptilum gracile, Echinus affinus
Hecker, 1990
Species replacement with depth was gradual in flat areas and abrupt in steep areas.
Geographic variation was observed related to glacial inputs/hard substrate.
Lowest densities on middle slope
Depth ranges are narrow on upper slope and broad on lower slope
Hecker, 1990
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HECKER, 1990
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ExamplesAlong Gayhead Bermuda Transect Gastropods and cumaceans show narrower depth ranges than polychaetes and brittle stars.
In N. Atlantic, sharpest changes are at shelf, and a zone of 400-1000 m is reflected in megafaunal changes (Sanders, Grassle, Haedrich, Rex).
N. Atlantic studies support a step model, with biggest changes at 200 m, 400-600 m, 1000 m, 1400 to 1600 m, 2000 m.
Echinoderms 800-1200 m and 1800 m - Rockall Trough. Agree with Bay of Biscay (Sibuet).
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Pacific ExamplesIn North Pacific Fish (Oregon/Washington) (Pearcy et al. 1982)
New species appear at: 400-700 correspond to OMZ boundary. 1900 to 2000m.
Species disappear at500-900 m2800-3100 m (floor of Cascadia Plain)
Holothurians show only gradual replacement (Carney & Carey 1977)
Mediterranean - (Emig 1997)Expression of upper bathyal zone is directly related to slopephysiography, thus slope profile should be given in studies.
Upper bathyal - belts of suspension feeders related to flow structure
Maximal density in upper bathyal (higher than shelf)
Zones: 100-600 m, 600-1300 m, 1400-1600 m, 1600-2000, > 2000
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Carneys OverviewCarney 2005
Upper BoundaryBiota Shelf to
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Compositional Zonation
MACROBENTHOSShallower Taxa -Amphipods, molluscs, polychaetes
Increasing in deep water --tanaid and isopod (peracarid) crustaceans-aplacophorans (mollusca)-sipunculans, priapulids
MEGABENTHOSSponges more common on the slope, echinoderms(holothurians, asteroids,brittle stars) below
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Zonation of Body SizeWITHIN TAXALarger size species found at deep end of taxon range
Asellote isopods - smallest genera < 250 m, largest > 1000 mTanaids,GastropodsForaminifera.
ACROSS TAXADecrease in average body size with depth - replacement of large by small species(except fish in NW Atlantic)
Lampitt et al. 1986 -Porcupine Seabight
At shallow depths large species dominate biomassAt deeper depths small species dominate biomass
***** Small species - shallow:deep
11% vs 34% of biomass 93% vs 98% of numbers
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Zonation of Feeding ModeReduction in suspension feeding &increase in deposit feeding with depth
Replacement of sedentary deposit feeders with mobile deposit feeders at deeper depths. (Fauchald and Jumars 1979)
50:50 surface and subsurface-deposit feeders at depth.
Taxon Rates of Species Change with DepthDo big and little animals show similar zonation?
Is zonation pattern taxon specific?
Rex 1977
Megafauna changed most rapidly with depthbut holothurians changed slowly (Carney and Carey 1982)
Predatory gastropods changed at an intermediate rate
Infaunal polychaetes changed slowest
Higher trophic levels have narrower bathymetric zones
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Testing Causes of ZonationBarnacle Manipulative Experiments
Dayton et al. 1982
-transplanted 250 Bathylasma coroliforme from 400 m to 25-40 m. Normally live > 100 m
Individuals survived for 2 y and produced larvae
Authors argued water movement restricted distribution.
Faunal Age Change with DepthOriginal belief :
the deeper the zone the more ancient the fauna(primitive protobranch bivalves, brotulid fishes)
primitive generalists do best
For holothurians and starfish,bathyal forms are most primitive,
abyssal and hadal forms are specialized
Radiation of diversity in the deep sea occurs for few taxaIlyarachnidae (isopods)
Early belief - diversification in Antarctic then submergence to deep
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Horizontal/Lateral ExtentDo vertical zonation patterns persist over wide horizontal ranges?
Wide lateral ranges off S. Australia (bathed in homogeneous Antarctic intermediate water).
Atlantic margin - more restricted lateral rangesAssociated with eastern, western boundary water masses
And strong gradients in productivity
Gayhead-Bermuda transect bivalves (Allen and Sanders 1996)Fauna more similar between adjacent basins than depthsIncreasingly cosmopolitan than depth.