Threats to Marine Ecosystems Threats to Marine Ecosystems and Biodiversityand Biodiversity

1.1. GeneralGeneral

2.2. Habitat Loss and DegradationHabitat Loss and Degradation

3.3. Resource ExtractionResource Extraction

4.4. Species Invasions and DiseasesSpecies Invasions and Diseases

5.5. Climate ChangeClimate Change

Source: NOAA

EXXON Valdez Oil Spill Trust Counciil; photolib.noaa.gov

GeneralGeneral• Human pressures on coastal resources are Human pressures on coastal resources are

compromising many of the ecosystem compromising many of the ecosystem services crucial to the well-being of coastal services crucial to the well-being of coastal economies and peopleseconomies and peoples

• The greatest threat to coastal systems is The greatest threat to coastal systems is development-related loss of habitats and development-related loss of habitats and servicesservices

• Coastal ecosystems and islands face greater Coastal ecosystems and islands face greater numbers of threats than others, because numbers of threats than others, because pressures are greater and because they are pressures are greater and because they are the downstream recipients of degradation the downstream recipients of degradation from afarfrom afar

Habitat Loss and Degradation

• The most serious consequences of biodiversity The most serious consequences of biodiversity loss occur when changes are irreversible: e.g. loss occur when changes are irreversible: e.g. habitat loss, species extinctions, population habitat loss, species extinctions, population extirpations, regime shifts extirpations, regime shifts

• The most important driver behind these large The most important driver behind these large scale impacts on biodiversity is land scale impacts on biodiversity is land conversion (including coastal/marine habitat conversion (including coastal/marine habitat loss) loss)

• The other drivers behind biodiversity loss The other drivers behind biodiversity loss differ in various ecosystems, and include over-differ in various ecosystems, and include over-exploitation, pollution, and climate change exploitation, pollution, and climate change

Resource Extraction• Many fisheries exceed Many fisheries exceed

sustainable limits of usesustainable limits of use

• The removal of small-scale The removal of small-scale heterogeneity associated with heterogeneity associated with the homogenization of the homogenization of habitats is an important habitats is an important cause of the loss of cause of the loss of biodiversity biodiversity

• Both over-exploitation Both over-exploitation beyond sustainable levels and beyond sustainable levels and fishing-induced or coastal fishing-induced or coastal development-related habitat development-related habitat destruction are major issuesdestruction are major issues

Source: T. Agardy

NOAA

• The global marine catch has increased more than four The global marine catch has increased more than four times in the past 40 years. in the past 40 years.

• Overfishing has pushed many fish populations into steep Overfishing has pushed many fish populations into steep declines. Catches are falling, even though fleets are declines. Catches are falling, even though fleets are fishing harder than ever beforefishing harder than ever before

• The U.N. Food and Agriculture Organization (FAO) The U.N. Food and Agriculture Organization (FAO) reports that seven of ten commercially targeted fish stocks reports that seven of ten commercially targeted fish stocks are either fully or heavily exploited (44 percent), are either fully or heavily exploited (44 percent), overexploited (16 percent), depleted (6 percent), or overexploited (16 percent), depleted (6 percent), or slowly recovering from previous overfishing (3 percent). slowly recovering from previous overfishing (3 percent).

Overfishing (= Intense Predation)

Pillaging the North Atlantic: species and the year that > fishing effort = no

increase in yield: ‘overfishing!’

C= codH=haddockP=plaiceR=redfishHk=hakeHg=herring

Ocean Fisheries

• > 109 people (mostly developing nations) depend upon marine fish for primary source of protein

• a 40 y ‘fishing boom’ has now ended: catch increasing steadily since 1950, but since 1989 world catch has stayed the same

• catch of ‘high value’ fish decreasing; catch of low value fish increasing

Exploitation of global fisheries

• Trawlers often scrape the same area several times Trawlers often scrape the same area several times each year. Sea-floor species can be crushed and each year. Sea-floor species can be crushed and displaced, and the types and availability of nutrients displaced, and the types and availability of nutrients changed. changed.

– Sediments stirred up by trawling can make water a Sediments stirred up by trawling can make water a thousand times cloudier than normal, limiting thousand times cloudier than normal, limiting resettlement and feeding of plants and animalsresettlement and feeding of plants and animals

Overfishing: Gear Impacts

Trawling

Beam trawl-how to destroy benthichabitats

Effects of scallop dredgingon a gravel bottom:George’s Bank: 84 m depth

Un-fished area

Fished area 500 m away

Frequency of trawling in some representative areas

The rapid decline of the orange roughy fishery

Red: est. biomassBlue: catch

Overfishing: Continued

• There is great difficulty in sustaining global fisheries production. In response to declines of big, slower growing species, fishers have begun "fishing down the food chain", targeting smaller species of less value, but which can play critical roles in food webs.

• The most glaring crises of global fisheries include:

– over-capitalization of the industry which has led to the buildup of excessive fishing fleets, particularly of the larger-scale vessels catching too many fish.

Overfishing: Continued• Government subsidies enabled vessels to operate in

conditions that are uneconomic and environmentally unsound. Fleets migrate globally to find more lucrative fishing opportunities. Subsidies also supported a spree in new vessel construction in recent years.

• Increased fishing pressure and competition among fishing nations severely stresses fish stocks and the marine environment. The use of unselective fishing gear results in millions of tons of unwanted bycatch being dumped overboard annually. Many millions of other animals are incidentally killed by fishing fleets.

““Discards” inDiscards” inthe fishing the fishing industry: industry: A.K.A.A.K.A.‘BYCATCH’‘BYCATCH’

Overfishing: Indirect Effects of Fishing on Food Webs (bycatch

cont.)• Driftnets drown by-catch

– With nearly invisible filament mesh, enormous driftnets catch and hold fish by the gills. •Driftnets also entangle and drown birds,

sharks, whales, and dolphins.

– The by- catch problem was so dire that the UN banned large- scale driftnetting on the high seas in 1993.

•Smaller driftnets are still used in coastal waters, including those of the U.S

The high seas driftnet fishery

• Fishing can be an agent of selection, affecting age Fishing can be an agent of selection, affecting age distribution, age and size at maturity, and growth distribution, age and size at maturity, and growth

• Fishing can alter species composition and Fishing can alter species composition and interactions among fished species and their prey. interactions among fished species and their prey.

• Fisheries often begin on large predators but their Fisheries often begin on large predators but their reduced numbers may lead to increased numbers reduced numbers may lead to increased numbers of prey species, which may themselves become of prey species, which may themselves become fished. fished.

• Intense fishing can lead to dominance by r-selected Intense fishing can lead to dominance by r-selected species, which often become major parts of mature species, which often become major parts of mature fisheries. Other species can also be affected; e.g., fisheries. Other species can also be affected; e.g., fishery discards have caused long-term changes in fishery discards have caused long-term changes in seabird species composition. seabird species composition.

Overfishing: Impacts on Biodiversity

Overfishing: Indirect Effects

Overfishing: large marine herbivores

• Losses of herbivorous Losses of herbivorous green turtles and fishes are green turtles and fishes are thought to be partly thought to be partly responsible for low levels responsible for low levels of seagrass grazing and of seagrass grazing and algal overgrowth of coral algal overgrowth of coral reefsreefs

Overfishing: A few success stories

• One success story, One success story, Spanish mackerel in Spanish mackerel in the Gulf of Mexico are the Gulf of Mexico are no longer overfished no longer overfished and, in fact, have and, in fact, have become a sustainable become a sustainable fishery.fishery.

• Pompano are also Pompano are also recovering in the Gulfrecovering in the Gulf

The three main “failings” of fisheries

• Oceans are a ‘free for all’, and regulatory bodies make weak commitments to preserve stocks and then fail to follow through

• Fishing fleets are subsidized by nations: $20 billion globally

• Conservation measures: there are few closed seasons and limits to total catch

• http://www.learner.org/courses/envsci/unit/text.php?unit=9&secNum=0# Jackson video

Exotic Species in the Oceans

• Invasion of marine areas by non-native species is a major Invasion of marine areas by non-native species is a major threat. The National Research Council's study threat. The National Research Council's study "Understanding Marine Biodiversity: A Research Agenda "Understanding Marine Biodiversity: A Research Agenda for the Nation“ says it is one of the five most critical issues for the Nation“ says it is one of the five most critical issues facing marine life. facing marine life.

• The ecological consequences of invasions include: The ecological consequences of invasions include: – habitat loss and alterationhabitat loss and alteration– altered food websaltered food webs– creation of novel and unnatural habitats that may be creation of novel and unnatural habitats that may be

colonized by other exotic speciescolonized by other exotic species– abnormally effective filtration of the water columnabnormally effective filtration of the water column– hybridization with native specieshybridization with native species– highly destructive predators; and highly destructive predators; and – introductions of pathogens and disease introductions of pathogens and disease

Ecosystem characteristics that may favor successful invasions

• The invaded habitat is climatically matched with the The invaded habitat is climatically matched with the original habitatoriginal habitat

• The community is an early successional one; thus, there The community is an early successional one; thus, there may be low diversity and absence of similar species. may be low diversity and absence of similar species.

• Lack of natural enemiesLack of natural enemies

• Lack of keystone specieLack of keystone speciess

• Heavily polluted or disturbed environments Heavily polluted or disturbed environments

Possible characteristics of successful invaders

• r-selected species with short generation r-selected species with short generation times, high fecundity, high population times, high fecundity, high population growth ratesgrowth rates– but some suggest a role for shifts but some suggest a role for shifts

between r and K strategiesbetween r and K strategies

Non-native Pathways of Introduction

• AquacultureAquaculture

• Aquarium tradeAquarium trade

• Biological controlBiological control

• Boats and shipsBoats and ships

• Channels, canals, locksChannels, canals, locks

• Live baitLive bait

• Nursery industryNursery industry

• Scientific research institutions, schools and public Scientific research institutions, schools and public aquariumsaquariums

• Recreational fisheries enhancementRecreational fisheries enhancement

Exotic Species: Ballast Water

TT

• To maintain stability ships fill To maintain stability ships fill ballast tanks with water. Large ballast tanks with water. Large ships often carry millions of ships often carry millions of gallons of ballast water. As a gallons of ballast water. As a ship loads ballast it also loads ship loads ballast it also loads many organisms. Ballast water many organisms. Ballast water is carried from one port to is carried from one port to another, where the water may another, where the water may be discharged.be discharged.

Exotic Species: Ballast Water (2)

• Perhaps 3,000 species per day Perhaps 3,000 species per day are transported around the are transported around the world. Most don’t survive, but world. Most don’t survive, but some thrive in their new some thrive in their new homes. These invaders can homes. These invaders can cause disruptions to cause disruptions to ecosystems, economies, and ecosystems, economies, and may carry human diseases. may carry human diseases.

• The Int’l Maritime Org. and The Int’l Maritime Org. and the U.S. government the U.S. government recommend open ocean ballast recommend open ocean ballast water exchange; however, few water exchange; however, few countries have adopted this. countries have adopted this.

Exotic Species: Nutria

• Nutria, from South America, Nutria, from South America, were introduced into Maryland were introduced into Maryland and La. in 1940’s & 50s for fur and La. in 1940’s & 50s for fur production. Since the 1970s, production. Since the 1970s, there has been a weak demand there has been a weak demand for furfor fur

• Nutria burrows normally extend Nutria burrows normally extend 4 to 6 ft. into marshes (but may 4 to 6 ft. into marshes (but may be as long as 150 ft.)be as long as 150 ft.)

• Damage first noted in the early Damage first noted in the early 1990's, and $millions in 1990's, and $millions in damages have accumulated damages have accumulated

Exotic species: Nutria (2)

• Nutria herbivory can have Nutria herbivory can have dramatic impacts on coastal dramatic impacts on coastal landscapes , and nutria have landscapes , and nutria have been implicated in large been implicated in large scale losses of marsh in scale losses of marsh in Maryland. Maryland.

• What was once continuous What was once continuous marshland (above) now marshland (above) now appears as fragmented appears as fragmented remnantsremnants

Solutions to the Nutria Solutions to the Nutria ProblemProblem• From the Dallas Morning News on July 7, 1997 “A From the Dallas Morning News on July 7, 1997 “A

nutria a day helps keep erosion at bay: Louisianians nutria a day helps keep erosion at bay: Louisianians urged to eat rodents, save coast”urged to eat rodents, save coast”

• "A young nutria tastes a lot like rabbit," Mr. Windom "A young nutria tastes a lot like rabbit," Mr. Windom (a La. Wildlife and Fisheries biologist) said, adding (a La. Wildlife and Fisheries biologist) said, adding that they can be fried, barbecued or cooked numerous that they can be fried, barbecued or cooked numerous

other ways.other ways.

EutrophicationEutrophication• Increased population density within watersheds has led Increased population density within watersheds has led

to dramatic increases in nutrient inputs to coastal to dramatic increases in nutrient inputs to coastal waterswaters

– increases range between 2 and 20 fold over increases range between 2 and 20 fold over preindustrial agepreindustrial age

• Consequences of eutrophicationConsequences of eutrophication

– elevated phytoplankton production coupled with elevated phytoplankton production coupled with stratification of the water column leads to hypoxia stratification of the water column leads to hypoxia and anoxiaand anoxia

– fish kills, reduced light for seagrasses, increased fish kills, reduced light for seagrasses, increased incidence of harmful algal bloomsincidence of harmful algal blooms

Worldwide “Dead Zones”

Eutrophication: Harmful Algal Blooms

Marine Diseases

Are much more prevalent in the world’s oceans in the past few decades, and this has spurred a great deal of research into the causes of these disease outbreaks.

Marine Diseases:Black Band Disease and Coral Reef Losses

• Black band disease Black band disease caused caused significant coral losses significant coral losses

– 1973-74 in Bermuda and 1973-74 in Bermuda and Florida Keys, in 1978 Florida Keys, in 1978 AcroporaAcropora corals in Florida corals in Florida

– 1985-86 in Florida again 1985-86 in Florida again

– The major component is a The major component is a cyanobacterium and other cyanobacterium and other microorganisms, including microorganisms, including sulfate-reducing bacteria and sulfate-reducing bacteria and heterotrophic bacteriaheterotrophic bacteria

White Band Disease

• First reports of tissue slowly First reports of tissue slowly peeling off elkhorn and staghorn peeling off elkhorn and staghorn corals at Tague Bay, U.S. V. I. corals at Tague Bay, U.S. V. I.

– The loss of tissue resulted in a The loss of tissue resulted in a band of white skeleton and this band of white skeleton and this was named was named white-band disease white-band disease (WBD). (WBD).

– Unlike BBD, despite intensive Unlike BBD, despite intensive study, no microorganisms could study, no microorganisms could be found be found

Additional coral diseases

Dark Spots DiseaseDark Spots Disease

Rapid Wasting DiseaseRapid Wasting Disease

Red Band DiseaseRed Band Disease

White PlagueWhite Plague

Yellow Band DiseaseYellow Band Disease

Marine Diseases: The loss of Diadema antillarum in the Caribbean

• Black urchin plague occurred Black urchin plague occurred in the Caribbean and caused in the Caribbean and caused 98% mortality within 10 days 98% mortality within 10 days of the first signs of the of the first signs of the disease in a new locality.disease in a new locality.

– Unlike other diseases, Unlike other diseases, which were localized, black which were localized, black urchin plague spread from urchin plague spread from Venezuela to Bermuda, Venezuela to Bermuda, reducing populations to 1-reducing populations to 1-7% of former levels.7% of former levels.

Consequences of Diadema Dieoff

• Algal overgrowth Algal overgrowth of coral reefsof coral reefs

• Loss reef Loss reef productivity & productivity & covercover

• Lost ecosystem Lost ecosystem productivityproductivity

Marine Diseases-Seagrasses

• Labyrinthula is a slime mold that could be responsible for mass mortality of seagrass .

• In 1931, observers noticed blackish-brown discolorations, a loss of leaves and death of the eelgrass along the U.S. east coast

• By 1933, this "disease" had decimated 90% of all eelgrass in the North Atlantic.

Occurrence of Labyrinthula in Florida Bay

Climate Change• The geographically largest scale impacts to coastal systems The geographically largest scale impacts to coastal systems

are caused by global climate changeare caused by global climate change

• Warming of the world’s seas affects species by: Warming of the world’s seas affects species by: - Changing sea level faster than most can adapt;Changing sea level faster than most can adapt;- stressing temperature-sensitive organisms such as corals;stressing temperature-sensitive organisms such as corals;- changing current patterns to interfere with important changing current patterns to interfere with important

processes like recruitmentprocesses like recruitment

• Global warming also changes the temperature, salinity and Global warming also changes the temperature, salinity and aciditiy of estuarine and nearshore habitats and exacerbates aciditiy of estuarine and nearshore habitats and exacerbates the problem of the problem of eutrophicationeutrophication

Climate Change and Disease

• Warming can increase the transmission rates of Warming can increase the transmission rates of pathogens and hasten the spread of many forms of pathogens and hasten the spread of many forms of human and non-human disease.human and non-human disease.

• In most if not all cases, global climate change impacts In most if not all cases, global climate change impacts act in negative synergy with other threats to marine act in negative synergy with other threats to marine organisms, and can be the factor sending ecosystems organisms, and can be the factor sending ecosystems over the threshold levels for stability and over the threshold levels for stability and productivity. productivity.

Methods to Conserve Marine Biodiversity

1.1. Spatial management through Spatial management through zoning and marine protected zoning and marine protected areasareas

2.2. RestorationRestoration

3.3. Fisheries ManagementFisheries Management

4.4. Integrated coastal zone Integrated coastal zone managementmanagement

5.5. Regional & international Regional & international agreements/treatiesagreements/treaties

Kevin Frey © CBC-AMNH

West Andros Island, BahamasSource: T. Agardy

Spatial management through zoning and marine protected areas

(MPAs)

Individual sites recognized for their valuable services Individual sites recognized for their valuable services are sometimes protected through zoning regulations are sometimes protected through zoning regulations and other spatial management interventions such as and other spatial management interventions such as marine protected areas (MPAs) marine protected areas (MPAs)

Restoration

• Some key coastal habitats Some key coastal habitats such as mangrove forests, such as mangrove forests, marshes, and seagrass marshes, and seagrass meadows can be, and are meadows can be, and are being, restoredbeing, restored

• In general, however, the In general, however, the costs of restoration far costs of restoration far exceed costs of protecting exceed costs of protecting the natural habitatthe natural habitat

Fisheries Management

• Management of living marine resource use has been Management of living marine resource use has been practiced for several centuriespracticed for several centuries

• Modern fisheries management has moved away from Modern fisheries management has moved away from stock-by-stock and single species management to stock-by-stock and single species management to broader, ecosystem-based managementbroader, ecosystem-based management

• Fisheries management tools include quotas on take, Fisheries management tools include quotas on take, gear restrictions, access restrictions, seasonal or other gear restrictions, access restrictions, seasonal or other timing restrictions, and MPAstiming restrictions, and MPAs

Integrated coastal management

• Though coastal management is spreading around the Though coastal management is spreading around the world, management has not kept pace with world, management has not kept pace with degradationdegradation

• Specific approaches have shortcomings in managing Specific approaches have shortcomings in managing complex issues such as biodiversitycomplex issues such as biodiversity

• An integrated management response is needed to An integrated management response is needed to conserve most aspects to biodiversity, especially at conserve most aspects to biodiversity, especially at the ecosystem levelthe ecosystem level

Regional & intl. agreements/ treaties

• Most marine species cross the boundaries of Most marine species cross the boundaries of individual countries, making regulation beyond the individual countries, making regulation beyond the control and responsibility of any individual nation control and responsibility of any individual nation (e.g., spiny lobsters and corals in the Fla. Keys)(e.g., spiny lobsters and corals in the Fla. Keys)

• International/Regional treaties provide a legal International/Regional treaties provide a legal framework for marine conservation action, resource framework for marine conservation action, resource regulation, and scientific research on a broad scaleregulation, and scientific research on a broad scale

Constraints to Marine Conservation

• Time Lags Time Lags between perturbation to a system and the between perturbation to a system and the eventual effects on the system mean that anticipating eventual effects on the system mean that anticipating effects is difficulteffects is difficult

• Incomplete ecological understandingIncomplete ecological understanding (and corollary (and corollary incomplete sociological understanding), can be a major incomplete sociological understanding), can be a major constraint in effective conservationconstraint in effective conservation

• Lack of fundingLack of funding (for research, for monitoring and for (for research, for monitoring and for enforcement of regulations) is a hindranceenforcement of regulations) is a hindrance

• The The lack of awareness and political willlack of awareness and political will to change to change policies is perhaps the biggest constraintpolicies is perhaps the biggest constraint

Conclusions

•Marine ecosystems are extraordinarily complex and Marine ecosystems are extraordinarily complex and ecological understanding of marine ecosystems is limited, ecological understanding of marine ecosystems is limited, but enough is known that better management action can be but enough is known that better management action can be takentaken

•Establishing adaptive management regimes will allow us to Establishing adaptive management regimes will allow us to gain important marine ecological information quicklygain important marine ecological information quickly

•Integrated approaches and international cooperation are Integrated approaches and international cooperation are needed to conserve marine ecosystems and marine needed to conserve marine ecosystems and marine biodiversitybiodiversity