|Gradually marine scientists all over the world begin to realise that marine reserves cannot work in seas where other threats remain, like pollution from the land. They also question the merit of a reserve that cannot be managed to reach its objectives. This page contains summaries of relevant articles from the international literature. Any environment that degrades is unsustainable.|
Human impacts on temperate kelp forests and tropical coral reefs continue to cause dramatic changes to the biotic structure of these habitats (e.g., McClanahan and Muthiga 1988, Jones et al., 1993, Hughes 1994, Steneck and Carlton 2001). However, few have examined the consequences of declining kelp and coral cover for the biodiversity of mobile organisms using these habitats.
In this paper, reef-associated fishes are used as an indicator of the ecological price that the habitat-user pays for habitat degradation. While there are some fishes that play key “top-down” roles in both kelp forest and coral reef habitats, by far the greatest biodiversity of fish species are likely to be influenced from the “bottom-up”.
There are striking parallels between temperate and tropical reefs in fish-habitat interactions. In both kelp forest and coral reef systems, different biotic habitats are always associated with recognizably different fish communities. In both systems, greater fish biodiversity is always associated with habitats of greater complexity. Habitat degradation results in deterministic changes to the structure of fish communities, regardless of whether they are caused by global warming, pollution, or the exploitation or introduction of keystone predators, grazers (urchins, crown-of-thorns) or habitat-forming organisms (kelp, corals). Moderate disturbance to habitats is likely to be an important process that maintains fish species diversity, because it creates patchiness and promotes spatial heterogeneity. However, chronic or severe disturbance establishes homogeneous habitats that are the end point of a phase shift from one habitat type to another. Inevitably, this results in a decline in fish biodiversity through local extinction.
Unless these shallow water ecosystems are effectively managed, the following predictions can be made. Local extinctions will progress through regional extinction to global extinctions as the scale of human disturbance increases. The fish species most threatened are those with specialized habitat requirements and those with small geographic ranges. It is estimated that the extirpation of corals in tropical Australia would result in
the regional extinction of obligate coral specialists (10- 15% of reef fish species). However, most tropical fishes have some resilience to global extinction because of their large geographic ranges. A lower proportion of fishes in temperate Australian kelp-forests are likely to be affected by loss of kelp, as there are relatively few kelp specialists (<5% of species). However, specialists on temperate reefs are at a greater risk of global extinction because of their relatively small geographic ranges.
Clearly, human impacts on habitat-forming organisms (kelp, corals) and key habitat-drivers (urchins, starfish) must be ameliorated if fish biodiversity is to be maintained. Marine reserves have proven to be an effective tool in re-establishing natural habitat dynamics, where exploitation has proven to be the key human impact. However, marine reserves alone do not work when habitat changes are driven extrinsic processes that do not recognize reserve boundaries. No reef fish has or is likely to be exploited to extinction. Global warming represents the greatest threat to reef fishes, because it is the most efficient at destroying habitat-forming organisms (e.g., coral bleaching, kelp disease) and can modify the aquatic environment over large spatial scales.
Hughes, T.P. (1994) Catastrophes, phase shifts, and large-scale degradation of a Caribbean coral reef. Science. 265, 1547-1551.
Jones, G.P., R. Cole and C. N. Battershill (1993) Marine Reserves: Do they work? In: “The Ecology of Temperate Reefs: Proceedings of the Second International Temperate Reef Symposium, Auckland”, pp. 29-45. NIWA Publications, Wellington.
McClanahan, T.R. and Muthiga, N.A. (1988) Changes in Kenyan coral reef community structure and function due to exploitation. Hydrobiologia. 166, 269-276.
Steneck, R.S. and Carlton, J.T. (2001) Human alterations of marine communities. Students beware! In: “Marine community ecology” (Bertness, M., Gaines, S. & Hay, M. eds.), pp. 445-468.
Jameson S C, Tupper M H, Ridley J M. 2002. Mar Poll Bull 44 (2002):1177-1183
The great majority of marine protected areas (MPAs) fail to meet their management objectives. The authors recommend a radically different approach for MPAs to be effective conservation tools. Firstly they should be located in areas free from uncontrollable stressors that degrade the environment. Secondly they should be managed with a view of achieving their objectives within the budget provided. This should be considered beforehand and assessed regularly.
Of the 1306 MPAs surveyed by Kelleher et al (1995) only 31% were achieving their objectives. Obviously we should not call an area 'protected' when it is not.
The three screen doors recognised by the author are:
Kelleher G, Bleakley C, Wells S. 1995: Global representative
system of marine protected areas. The World Bank, Washington. 4 vols.
The Great Barrier Reef is facing an increasing threat from a decline in the water quality in the catchments draining into the Reef lagoon. The Commonwealth and Queensland Governments have agreed, through a Memorandum of Understanding to jointly developing a Reef Water Quality Protection Plan to protect the Reef from land based sources of pollution
http://www.ea.gov.au/coasts/pollution/reef/science/index.htmlComments are sought on the Draft Reef Water Quality Protection Plan from all members of the public and interested stakeholders. The feedback form is available from the Queensland Government web site.
http://www.thepremier.qld.gov.au/reefwater/downloads/haveyoursay.docThe Panel found that there are clear indications that major land use practices in the Reef catchment have led to accelerated erosion and greatly increased the delivery of nutrients over pre 1850 levels. The reasons for this decline are varied but relate to activities within the river catchments, such as the extensive grazing practices in the drier catchments and overgrazing in general, urban development, agricultural production, water use practices, extensive vegetation clearing and wetland drainage on coastal plains and development on acid sulphate soils.
The Panel found that there is clear evidence of the effect of these
practices on some rivers, estuaries and inshore areas. Reefs at a number
of inshore locations along the coast have been disturbed and have remained
in a disturbed state. These reefs exhibit characteristics consistent with
altered ecological function due to enhanced nutrient availability or sedimentation.
Evidence of impacts on offshore areas of the Reef is not well understood,
however information from overseas shows that by the time such effects are
obvious the system would be almost irreparably damaged. In light of the
above factors the Panel confirmed that there is a serious risk to the long
term future of at least the inshore reef area and that action is necessary
to avoid such damage.
The Panel believes that an integrated resource management (ICM) approach to dealing with the issue is the best approach and supports the concepts of risk assessment and target setting. To this end the Panel found that the GBRMPA Action Plan has value on a broad basis, but requires significant refinement, particularly at a sub-catchment level. The future development of water quality targets and risk classification must include community input and are best achieved through existing regional structures using specific local water quality data.
Unfortunately the Panel embraces unproved methods of risk assessment and target setting, rather than getting on with reducing sediment runoff from all the sources mentioned in the frist paragraph.
Oceans policies: www.ea.gov.au/coasts/international/index.html
The deep oceans contain a vast diversity of life forms, many of which are still being discovered. Some scientists estimate that over 100 million species may inhabit the high seas. What happened to the TOTAL number of species on this planet, estimated at 5-14 million? This marine life is little understood, and scientific knowledge to guide management is very limited. There are many examples of severe, and potentially irreversible, damage to the biodiversity and environment of the high seas under present management and jurisdictional arrangements. Please specify because the seas are the least threatened environments on Earth. Bioodiversity is about viable populations of all species, not necessarily about pristine populations.
In order to work towards addressing these issues, Australia will host a major international conference on high seas biodiversity from 16-20 June 2003. Workshop on Ecosystem Based Management (EBM) - "Beyond Biodiversity - Sustainable Management and Conservation of the Oceans using EBM". Marine Pollution from Land-based Sources
By far the greatest sources of marine pollution are those that are land-based. For both pollution mitigation purposes and the conservation of marine biodiversity it is critical that international efforts to address land based sources of marine pollution are accelerated. In answer to this pressing need and as a result of Agenda 21, the Global Program of Action for the Protection of the Marine Environment from Land-Based Activities (GPA) was adopted by over 100 governments, including Australia, in Washington D.C. on 3 November 1995.
The GPA is a non-legally binding instrument, aimed at preventing the degradation of the marine environment from land-based activities by facilitating the realisation of the duty of States to preserve and protect the marine environment. The sources of marine pollution it targets include sewage, persistent organic pollutants, radioactivity, metals, oils, nutrients, sediment mobilisation, litter and habitat destruction. It proposes action at primarily the national and regional levels with some coordination tasks at the global level. The GPA is designed to be a source of practical guidance to States in taking actions within their respective policies, priorities and resources.
Australia has been an active participant in meetings to discuss the
development, implementation and review of the GPA.
The GPA in Australia. http://www.gpa.unep.org .
http://www.gpa.unep.org/about/default.htm Document explaining the rationale for GPA, a Dutch initiative. This document can now be found on the Seafriends website: /issues/cons/gpa.htm.
A new area of black water has formed off Sanibel Island
Copyright © 2000 Naples Daily News, Sunday, August 11, 2002
By CATHY ZOLLO, firstname.lastname@example.org and JEREMY COX, email@example.com
More than half of the coral in western Florida Bay, north of the Florida
Keys was destroyed in the past 12 months, and
Porter said his team of researchers measured a 60 percent loss of over
one year, "which is the highest rate of loss we have ever seen anywhere
in the Florida Keys in a single year," he said. "Even Hurricane Georges
did not do this kind of damage."
Five coral species were completely wiped out in areas Porter monitors in the bay, a an area of patch reefs north of the lower third of the island chain. He noted the demise of centuries-old boulder corals, and large numbers of other bottom dwellers such as sea squirts, sea biscuits and sponges.
Joining Porter in his assessment of the area's sea life is marine collector Ken Nedimyer. "Most of the brain corals in the Northwest Channel are dead," Nedimyer said. "I could go on. The Middle and upper Keys look good, but the Lower Keys and Key West were hammered. But we're not supposed to worry because this is a natural phenomenon."
Officials in the spring characterized the event as naturally occurring and similar to a 100 years flood. No assessment is yet in on the area hundreds of square miles in size and farther north where satellite pictures showed the water pooled for months beginning in November 2001 and then washed over the Keys.
What worries some environmentalists and others along the Southwest Florida coast is the appearance in recent weeks of another mass of black water that formed off Sanibel Island near where the Caloosahatchee River — an outlet for Lake Okeechobee — empties into the Gulf of Mexico. Jim Anderson, a Sanibel pilot, said he at first thought the water was oil. Others who live along the Caloosahatchee River say they've seen a drop in water quality there over recent weeks.
"I noticed when waves come on shore, the water is thick and black,"
said Mitrah Bakhtian, who's lived along the river for seven
years. Satellite pictures show a cloud of dark water hugging the Florida coast and concentrating south of Cape Romano, though this water mass isn't as large as the one in the spring.
"The images are a bit similar to what we saw in the winter black water event, but they are less dark and appear more brownish and they cover less (area) and are closer to the coast," said Chuanmin Hu, a researcher at the University of South Florida's Institute for Marine Remote Sensing. "This may or may not be the same thing we observed in the winter."
Hu checked the satellite data after hearing reports of black water, but he said there is no ongoing monitoring and interpreting program in place.
Scott Willis, spokesman for the Florida Marine Research Institute, said scientists are collecting water samples from the current mass of water and will be looking at those this week. Fishermen spotted the first event in January when it had become a mass bigger than Lake Okeechobee occupying the area between Cape Romano and the Florida Keys. It slowly moved south across the Keys by April.
pictures at the time showed the water had trailed along the west coast
of Florida from the Caloosahatchee and intensified when it reached western
Florida Bay off the Shark River just below Marco Island and Naples. Researchers
concluded later that the black water was a complex interaction among red
tide and other algae blooms mixing with river runoff, said Beverly Roberts
of FMRI. Few in the scientific community would say if they think July's
dark water is a repeat event, and Roberts said it could just as likely
be normal river runoff. Fresh water is much darker than sea water and would
float along the surface of the gulf. "That can extend miles into the gulf,"
part of the Executive Summary of the extensive report
Stephen R Palumbi, January 14, 2003
Cick here for the executive summary on this site.
More than 60 percent of our coastal rivers and bays are moderately to severely degraded by nutrient runoff. This runoff creates harmful algal blooms and leads to the degradation or loss of seagrass and kelp beds as well as coral reefs that are important spawning and nursery grounds for fish. Each summer, nutrient pollution creates a dead zone the size of Massachusetts in the Gulf of Mexico. These types of problems occur in almost every coastal state and the trends are not favorable. If current practices continue, nitrogen inputs to U.S. coastal waters in 2030 may be as much as 30 percent higher than at present and more than twice what they were in 1960.
This ignores the natural nutrients released from mud entering the ocean, constituting a much larger problem. It also ignores sedimentation which suffocates marine organisms while reducing water clarity. Scientists have not caught up with the seriousness and pervasiveness of the situation.
We report a massive region-wide decline of corals across the entire Caribbean basin, with the average hard coral cover on reefs being reduced by 80%, from about 50% to 10% cover, in three decades. Our meta-analysis shows that patterns of change in coral cover are variable across time periods but largely consistent across subregions, suggesting that local causes have operated with some degree of synchrony on a region-wide scale. Although the rate of coral loss has slowed in the past decade compared to the 1980s, significant declines are persisting. The ability of Caribbean coral reefs to cope with future local and global environmental change may be irretrievably compromised.
The dramatic loss of marine wildlife recorded last year in the Western Baltic Sea between Denmark, Germany and Sweden is largely the result of extreme weather conditions and an increase in nutrients resulting from human activities, according to the findings of a new report released by the Helsinki Commission (HELCOM).
Last fall, HELCOM and European Commission joined forces to investigate exceptional oxygen depletion in the Western Baltic that had led to hundreds of dead fish being washed ashore along the east coast of Jutland, Denmark.
Widespread and long lasting severe oxygen depletion was observed in the Kattegat, the Sound and the Baltic Sea in late summer and autumn 2002, some of the worst ever recorded.
In several areas, extreme oxygen deficiency led to the release of highly toxic hydrogen sulfide from marine sediments. As a result, creatures living near the bottom of the sea died and, in October 2002, the Jutland coast was littered with fish carcasses.
Algae bloom in the Baltic Sea due to eutrophication (Photo courtesy
The report reveals that the oxygen deficiency was caused in part by heavy rain and snow, leading to the runoff of higher than usual levels of nutrients from agriculture, urban wastewater and air pollution into the sea.
In addition, low wind levels and high air pressure minimized exchanges between different water levels in the Baltic. The report recommends stricter controls on nutrients reaching this inland sea to prevent future oxygen depletion.
In the European Union, intensive agricultural methods make farmland a major source of waterborne nutrient pollution.
Research Commissioner Philippe Busquin said, “We must do more to reduce the level of man-made nutrients polluting the Baltic Sea and the destruction of its precious ecology. We cannot ignore nature's alarm calls, and must ensure that our research findings help shape appropriate international policies.”
The Baltic Sea is ecologically unique, being generally shallow and almost stagnant, the Commission explains. It is dominated by a substantial input of freshwater from many rivers and as well as rain and snow, and by the limited exchange of more saline water over the shallow entrances to the North Sea.
Scientists have found that the Baltic is particularly sensitive to the impact of pollution and overexploitation. It is also under pressure from the housing, agriculture, industry, traffic, energy generation, fishery and shipping needs of over 85 million people within its large drainage area.
A preliminary version of the Helsinki Commission report was used in the preparatory work for the HELCOM Ministerial Meeting, which took place on June 25 in Bremen, Germany. Environment Commissioner Margot Wallstrom participated at this meeting where a package of measures for the protection of the Baltic marine environment was agreed.
The ministers agreed to make agriculture more environmentally sustainable by improving agricultural practices to ensure efficient use of nutrients while minimizing any adverse impact on the environment.
European Union laws such as the Nitrate and Urban Waste Water Directives must be fully implemented, the ministers agreed.
Following the initiative of the HELCOM Monitoring and Assessment Group, an expert group was set up with Denmark, Germany, Sweden and the European Commission to analyze the development and causes of this situation using information gathered from marine biology, oceanography, and satellite remote monitoring.
Heike Herata chairs the HELCOM Monitoring and Assessment Group (Photo
The experts found that eutrophication, a condition in which the waters are extremely rich in nutrients such as fertilizer components, is still a major problem in the Baltic Sea.
The symptomatic problems of eutrophication include serious oxygen deficiency, extensive algal blooms and floating mats of decaying seaweed in coastal waters. The condition is still common, in spite of substantial efforts to reduce nutrient inputs over a wide area.
Comparisons between recent years marked by specific weather events in the area revealed the key roles of snow, rain, and wind and air pressure in the oxygen balance of marine bottom waters.
The amount of snow and rain controls the nutrient loading of surrounding rivers by soil erosion. Unseasonably late rains, combined with sunlight can also indirectly enhance marine plant production in surface waters, the expert group said. Wind and air pressure acts on the local supply of oxygen through water exchanges with the oxygen rich waters of the Skagerrak.
While weather conditions were the main trigger of the 2002 event, investigations revealed that the Baltic Sea is particularly vulnerable to oxygen depletion. Permanent separation of water strata, minimal reaction with the sea bottom, restricted flow patterns resulting from semi-enclosed bays and estuaries and shallow bowl shapes in the sea bottom all favour the isolation of bottom water masses and therefore limit reoxygenation, the scientists said.
The Baltic Sea region is one of the most naturally sensitive to oxygen deficiency in Europe. Some confined regions such as the Little Belt were already experiencing oxygen deficiencies 100 years ago, when nutrient discharges were relatively low. For several decades the main original cause of extended oxygen deficiency has been the nutrient supply in surface marine waters.
The Commission contribution indicates that the Belt Sea area has a very limited capacity to digest the organic matter and, indirectly, to assimilate any additional supply of nutrients. Further efforts are necessary to meet the 50 percent nutrient reduction target set by HELCOM.
But, the Commission said, even this might turn out to be insufficient to drastically reduce the likelihood of severe oxygen depletion in terms of geographical coverage and duration in the Western Baltic.
HELCOM is the governing body of the Convention on the Protection of the Marine Environment of the Baltic Sea Area, known as the Helsinki Convention, originally signed in 1974. Through intergovernmental co-operation between all the countries bordering the Baltic - Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia and Sweden - and the EU, HELCOM works to protect the marine environment from all sources of pollution and to take appropriate measures to counter and prevent pollution to save the environment in a sustainable way.
The convention was updated in 1992, when the European Union became a
member, and the updated convention came into force on January 17, 2000.
It covers the whole of the Baltic Sea area, including inland waters as
well as the water of the sea itself and the seabed. Measures are also taken
in the whole catchment area to reduce land based pollution.
|The marine ecosystem is like a big tent, and if we humans tear down a couple of supporting poles or chop through some of the guy ropes it affects the stability of the whole tent. Everything is connected.|
Everything is connected. From mountains to streams, to rivers, to estuaries, to harbours and finally to the sea, water flows down hill taking with it what comes its way. Pollutants that enter waterways on land inevitably end up in harbours and in the ocean. That which affects the ecology of harbours affects fish and their habitats. That which affects fish affects the fishing industry. Water quality, pollution control and green issues should therefore be of core interest to the seafood industry.
Major threats to harbour ecology: urbanisation
Big cities can massively damage the ecology of harbours near them. Dr Shane Kelly, team leader marine ecology Auckland Regional Council (ARC) says Auckland, straddling both the Waitemata and Manukau harbours and with a quarter of the country's population, is a prime example.
"Whatever people put sown stormwater drains ends up in the estuary, the harbour and then the sea. In Auckland water quality is damaged by many different kinds of human activity; by sediment runoff from new subdivisions, by sewage when stormwater overflows from old combined systems, by runoff from roads, industrial pollutants and toxins that people pour down drains."
"Toxins from burnt fossil fuels get washed off roads into drains. Heavy metals come from a variety of sources such as industry discharges, copper from car brake linings, zinc leached from unpainted galvanised roofs and from metals built into tyres."
All this ends up in the harbours. The ARC puts considerable effort and
expenditure into monitoring water quality, sedimentation and shellfish
contamination. Likewise it educates people, sets and enforces environmental
regulations, fines offenders and does what it can to keep the harbours
in its area healthy.
"Many parts of the southern Waitemata Harbour is in a sorry state", Shane says, "The surrounding catchment has a long history of urbanisation, are heavily developed and contains a substantial amount of industry (Avondale, Rosebank, Henderson). Many of the disposal systems are not as reliable as those in newer urbanised areas. The Tamaki Estuary is just as bad. Manukau harbour is becoming a good news story, though. For example, industries used to discharge heavily polluted industrial waste directly into the Mangere inlet. Industry has cleaned up its act and there has ben a progressive change in expectations of community and the attitude of industry. The Mangere sewage system was upgraded (opened late last year) and already there is a noticeable difference in the water quality in the Manukau. The environmental expectations of local Maori, who want to harvest Kai Moana from their customary reefs and shellfish beds has had a big influence on the process."
There is only so much that the likes of the ARC can do to clean up existing
pollution in harbours. The most effective approach to harbour water quality
is to stop pollutants from being used and getting into the watercourse
in the first place. An example of where this approach has worked well was
getting lead out of petrol in 1996. Since that time the lead levels in
Auckland's harbours have dropped away dramatically.
The same could be done with zinc. International research indicates that unpainted corrugated iron roofs are a major source of zinc. One roof does not make much difference but lots of roofs in a city, do and something as simple as a national standard requiring roofs to be painted may reduce the rate of zinc accumulation in our harbours and estuaries.
Shane says that it would be wise to ensure that cities don't sprawl and write off more harbours as they go. "It's better if cities go up rather than out because, even though the effect is worse, it's easier to contain. Cities should set urban limits but there is constant pressure from developers to subdivide new areas."
Increasingly people want to live by the harbour or the sea. Housing developments and site preparation is associated with sedimentation and septic tanks and community sewage systems are being stretched. The failure of either private or community based treatment systems can result in increased pathogens and viruses in the water. Septic tanks in old batches are not as efficient as new septic tanks and many can't cope with rapid increases of summer holiday effluent. The leakage, seepage and overflow runs downhill into the waterways, beaches and harbours.
Cows are large animals that can make a significant contribution to the bacterial contamination of streams and harbours through their effluent. Their pugging collapses stream banks and causes erosion and their grazing damages plant growth that otherwise may protect streams from sedimentation and effluent runoff.
Dairy and cattle farmers need to address riparian planting and keep cows out of creeks and harbour edges (see box Breathing new life back into the Whaingaroa). Bacterial contamination of streams, by sheep is not as significant as that of cows - they don't like getting their feet wet.
Also in rural areas there is runoff from fertiliser, pesticides and biocides, all of which do weird things to harbour habitats. Forestry provides a stable watercourse environment while the trees ae growing but becomes an issue when trees are felled. Clearfelling can create huge sedimentation problems in streams and harbours. Industrial activity in rural areas contributes to habitat destruction in harbours and streams. For example, the pulp and paper mill in Kawerau (Bay of Plenty) and the black river it helps to colour.
New Zealanders love boats and most boats don't have onboard treatment systems or holding tanks to deal with effluent. This becomes a major issue, in summer, when there is an influx of recreational boats up estuaries and harbours and the people on them discard sewage straight into the water.
Their effects on fishing
"Estuaries and harbours are important habitats for a whole range of fish species", says Dr Mark Morrison, fisheries ecologist with NIWA. "They are nursery grounds for snapper, kahawai, mullet, trevally and many other fish. Harbours are particularly important to juvenile fish on the West Coast, because they have less wave energy, are warmer, have higher productivity and provide structures that are safe havens from predators, compared to the high energy open coast."
"Fishermen and quota holders should look upon harbours as a critical bottleneck in fish production; harbours are vulnerable because they are the receiving end of anything that happens on land. These juvenile fish are the future adult stock and need to be protected.
The factors that damage harbour habitats are outlined above. Mark explains
in more detail how this damage can affect fish. "Sedimentation can smother
bottom communities and this has a cascade effect onto the fish that feed
on and around them. Sedimentation also affects turbidity and light levels,
and some visual feeders (for example trevally and kahawai) may be unable
to locate their food, adversely affecting their feeding abilities, and
potentially resulting in them growing more slowly. When harbours become
turbid, the fish species in them change and the high value species may
decline in abundance, so fishers ae losing value from the system.
"Three-dimensional living habitats such as sea grass and horse mussels can be really important habitats for fish; for example very small juvenile snapper, spotties, trevally and parore are more common in sea grass beds than in open bare harbour areas. New Zealand harbours have lost a lot of sea grass beds to sedimentation and pollution during the last 100 years; the decline in this important element of the system is likely to have reduced fish productivity and abundance.
"We (NIWA) are looking at estuaries and studying fish in their habitats and micro habitats, in an effort to understand more about these nursery grounds and how they affect the longer life cycle of fish and population dynamics. Through working on many North island harbours we are beginning to quantify some of the effects of environmental degradation and associated water quality on juvenile fish, and how estuaries contribute to coastal stocks. For example, we are currently working on the possibility of using fish ear-bones (otoliths) to provide chemical fingerprints for juvenile snapper coming from different westcoast estuaries - potentially allowing us to identify where individual adult fish originated from, and the relative proportions that different estuarine systems contribute to the adult stocks."
Their effects on aquaculture
Helen Smale, manager of the Marlborough Shellfish Quality Programme, knows well the value of water quality to New Zealand seafood industry. "New Zealand's aquaculture industry has set a goal of $1 billion export revenues by 2020. To achieve that we need innovative farming practices, new species and more water space. But the industry's success stands or falls on the purity of the growing waters and how our quality programmes monitor and assure that quality."
Helen explains that aquaculture demands the highest environmental standards and water quality and hygiene standards are pre-requisites for a successful industry. Shellfish are filterfeeders and are thus at the end of the food chain. They are the maritime version of the canary in the mineshaft. [this is incorrect because shellfish are but the second stage in the food chain: sunlight to phyto plankton to shellfish]
"The assurance of water quality faces a plethora of environmental challenges. One of the most immediate is virus contamination. Enteroviruses enter the water through human and other mammalian excreta. One scientific paper, based on research in the Gulf of Mexico, showed that one human stool was sufficient to contaminate an area one km long by 100m wide. Research closer to home, in Otago, revealed that enteroviral contamination of sediments near a sewer outfall does occur and that viruses are detectable at considerable distances from the outfall. [again incorrect, because every litre of seawater contains billions of virus particles, which are similar to and often indistinguishable from human enteroviruses. Perhaps what is meant are bacteria like the human gut bacterium Eschericia coli]
"We have a public policy failure in the inaction on policing the introduction of effluent, unconsciously through faulty septic tanks deliberately through known effluent outfalls, and carelessly through discharge from vessels. With or without marine farming, regional councils have a duty, under the Resource Management Act (RMA), to prevent the introduction of harmful contaminants into the environment." [Helen fails to mention that the largest threat to marine farming comes from the pollution it produces underneath the cages (salmon) and mussel farms, full of decomposing bacteria and viruses, which in turn infect the stocks above it with disease. Marine farms too are obliged under the RMA to prevent introducing harmful contaminants.]
While Helen has used viruses as an example there
are many contaminants entering our waterways. "Just as manufacturing industries
have progressively switched from quality control (weeding out defective
product) to quality assurance (preventing the production of defective units),
water quality management in New Zealand needs to adopt the same approach.
We achieve that by reducing, as far as practicable, the introduction of
the contaminants in the first place.
"This reduction will be achieved by a combination of the carrot and the stick. The stick is the regional councils taking their duties to eliminate harmful contamination of the water space much more seriously. The carrot is raising awareness amongst the public, especially amongst recreational users of coastal space, of the implications of their discharges from vessels and septic tanks. All New Zealanders benefit from a high standard of water quality."
"We must encourage, coerce and, if necessary, force regional councils to eliminate as far as practical the deliberate, accidental or careless introduction of effluent and other contaminants into the water space." says Helen. [Bravo! Begin with the marine farms immediately!]
The marine ecosystem is like a big tent, and if
we humans tear down a couple of supporting poles or chop through some of
the guy ropes it affects the stability of the whole tent - everything is
Maungahaumi te maunga
Waipaoa te awa
Te Aitanga a Mahaki te wi
Few people realise that the
a Kiwa - Gisborne Harbour is one of the largest nurseries of rocklobster
in New Zealand. Ian Ruru is a marine scientist and as part of his PhD is
studying this marine phenomenon.
Ian explains that the effects
of human intervention over the last 150 years have had the most dramatic
effect on the rivers and coastal environment. Degradation of both freshwater
and marine habitats locally has been caused mainly by soil erosion and
runoff from the Waipaoa catchment, and effluent discharge from Gisborne
city. Deforestation during the last century caused chronic soil erosion
that led to sedimentation in the rivers, sedimentation of the sea and a
decline in the productivity of the fisheries. The depletion of seafood
habitat, through unsuitable land use, is ironic considering the historical
and spiritual connection that his people have with the land and their intrinsic
belief in the need to care for it.
Toitu te marae o Tane,
Toitu te marae o Tangaroa, Toitu te Iwi.
Back in 1995 Raglan resident Fred Lichtwark, had a part-time job taking shellfish samples from the Whaingaroa (Raglan) Harbour for Health Waikato. His other occupation was commercial fishing. Both his jobs showed him how sick the harbour was; the shellfish couldn't be eaten after rain; the cockle beds were being smothered by sedimentation; the measured catch per unit effort was one of the lowest in New Zealand and the water was so filthy surfers got ulcers when they scratched themselves on rocks.
Fred has seen pristine harbours in the South Island and knew what Whaingaroa could be like. He had a yarn to a few people and put a notice in the local rag about a meeting to discuss harbour pollution. Sixty people turned up and Fred explained the basis of a plan he had worked out in his head. They liked it and formed an incorporated society, the Whaingaroa Harbour Care.
Fred explains, "The poor water quality was caused by effluent from farms: coliforms from sheep and cows piss and shit; fertiliser runoff; and sediment caused by cows damaging stream banks and pugging the foreshore, stream beds and swamps. It's an historical issue so there is no point in blaming farmers. Whaingaroa Harbour Care decided an effective approach would be to offer to fence off streams, rivers and foreshore for the farmers, on their land, and plant it in native trees."
To do this, the group needed money, to start a plant nursery and buy fencing material. They raised the funding from Environment Waikato and various other sources, persuaded Council to provide land for the nursery and got dole people and volunteers working at fencing and planting. Now, eight years on, 210km of fencing has been constructed (there is 50km to go) and the group grows and plants over 100,000 native trees a year.
"The farmers are happy because their stock is in better health and is more productive. They drink from troughs now, not their own effluent from streams, and they don't get bogged in mud. It's easier to muster too because stock don't hide down the banks."
There has been benefits to the fishery which supports eight commercial fishermen now - four years ago it was only three. The catch per unit effort is up, the shellfish are safe to eat, snapper and other table-fish are back in the harbour in big numbers, shelly beaches are forming where there was mud, surfers don't get sores and, last year there were three visits by pods of orca, for the first time in ten years.
By Alex Kirby
BBC News Online environment correspondent in Jeju, Korea
Published: 2004/03/29 06:46:24 GMT
Sea areas starved of oxygen will soon damage fish stocks even more than unsustainable catches, the United Nations believes.
The UN Environment Programme says excessive nutrients, mainly nitrogen from human activities, are causing these "dead zones" by stimulating huge growths of algae. Since the 1960s the number of oxygen-starved areas has doubled every decade, as human nitrogen production has outstripped natural sources. Unep made its remarks as it launched its Global Environment Outlook Year Book 2003.
About 75% of the world's fish stocks are already being overexploited, but Unep says the dead zones, which now number nearly 150 worldwide, will probably prove a greater menace. Unless urgent action is taken to tackle the sources of the problem, it is likely to escalate rapidly It quotes research by a team of scientists at the Virginia Institute of Marine Science in the US.
They concluded: "The history and pattern of human disturbance in terrestrial, aquatic, coastal and oceanic ecosystems have brought us to a point at which oxygen depletion is likely to become the keystone impact for the 21st Century, replacing the 20th Century keystone of overfishing." Ironically, Unep says, nitrogen is desperately needed in parts of the world, including much of Africa, where the lack of it is reducing farmers' yields.
The amount of nitrogen used as fertiliser globally is 120 million tonnes a year, more than the 90 million tonnes produced naturally.
Yet only 20 million tonnes of that is retained in the food we eat, with the rest washed away into rivers and out to sea. The burning of fossil fuels in vehicles and power plants, and of forests and grasslands, and the draining of wetlands all contribute more nitrogen to the cycle.
This leads to the explosive blooms of algae, tiny marine plants, which sink to the seabed and decompose, using up all the oxygen, and suffocating other marine life. Unep's executive director, Dr Klaus Toepfer, said: "Humankind is engaged in a gigantic global experiment as a result of the inefficient and often excessive use of fertilisers, the discharge of untreated sewage, and the ever-rising emissions from vehicles and factories. "Hundreds of millions of people depend on the marine environment for food, for their livelihoods and for their cultural fulfilment. Unless urgent action is taken to tackle the sources of the problem, it is likely to escalate rapidly."
Some of the dead zones are less than a square km in size, while others are up to 70,000 sq km. Examples include Chesapeake Bay in the US, the Baltic and Black Seas and parts of the Adriatic. One of the best-known is in the Gulf of Mexico, affected by nutrients washed down the Mississippi river. Other zones have appeared off South America, Japan, China, Australia and New Zealand. Not all are permanent: some appear annually or only intermittently.
Unep says reducing nitrogen discharges can restore the seas to health: an agreement by states along the River Rhine has cut the amount of nitrogen entering the North Sea by 37%. Other remedies include wasting less fertiliser, cleaning vehicle exhausts, and using forests to soak up excess nitrogen.
Unep launched its Geo Year Book, highlighting emerging issues, at the meeting here of its governing council from 29 to 31 March. Delegations from more than 150 countries are expected to take part.
© BBC MMIV
WEDNESDAY, 31 MARCH 2004
By MATT O'SULLIVAN, Dominion Post
Marine areas starved of oxygen and labelled "dead zones" are appearing off New Zealand's coast, United Nations scientists warn.
The claim is made in the UN Environment Programme's Global Environment Outlook Year Book 2003, which says the zones have recently been appearing off New Zealand, southeast Australia, Japan, China and South America. But New Zealand experts say they are mystified by the report and question where the UN agency got its information.
Dead zones in the seas and oceans are caused by an excess of nutrients – mainly nitrogen – from agricultural fertilisers, vehicle and factory emissions and wastes. Low levels of oxygen in the water make it difficult for fish, oysters and other marine creatures to survive.
Dr Janet Grieve, a biological oceanographer with the National Institute of Water and Atmospheric Research, said she was not aware of any oxygen-starved zones off New Zealand that would fall into the "shock-horror" category, and believed the report was somewhat misleading.
The Fisheries Ministry says New Zealand's fish stocks are in a healthy shape and are not threatened by oxygen-starved zones. "It would be an enormous concern if the waters around New Zealand were called a dead zone," a spokeswoman said. "We do not consider this a dead zone." Occasionally, fish were killed by algae blooms that remained for several weeks but nothing like that outlined by the UN agency, she said.
In their report, UN scientists identified nearly 150 oxygen-starved zones around the world, which they say pose major threats to fish stocks. They did not give details of where New Zealand's "dead zones" were.
Eco-Economy Update 2004-10; Copyright Earth Policy Institute 2004
June 16, 2004
Worldwide, there are some 146 dead zones--areas of water that are too low in dissolved oxygen to sustain life. Since the 1960s, the number of dead zones has doubled each decade. Many are seasonal, but some of the low-oxygen areas persist year-round.
What is killing fish and other living systems in these coastal areas? A complex chain of events is to blame, but it often starts with farmers trying to grow more food for the world's growing population. Fertilizers provide nutrients for crops to grow, but when they are flushed into rivers and seas they fertilize microscopic plant life as well. In the presence of excessive concentrations of nitrogen and phosphorus, phytoplankton and algae can proliferate into massive blooms. When the phytoplankton die, they fall to the seafloor and are digested by microorganisms. This process removes oxygen from the bottom water and creates low-oxygen, or hypoxic, zones.
Most sea life cannot survive in low-oxygen conditions. Fish and other creatures that can swim away abandon dead zones. But they are still not entirely safe--by relocating they may become vulnerable to predators and face other stresses. Other aquatic life, like shellfish, that cannot migrate in time suffocate in low-oxygen waters.
Dead zones range in size from small sections of coastal bays and estuaries to large seabeds spanning some 70,000 square kilometers. Most occur in temperate waters, concentrated off the east coast of the United States and in the seas of Europe. Others have appeared off the coasts of China, Japan, Brazil, Australia, and New Zealand. [Although NZ is due for dead zones, so far none have been detected. The small continent size of NZ makes it unlikely in the short term. Also, NZ's inshore seas are not deep enough. JFA]
The world's largest dead zone is found in the Baltic Sea, where a combination of agricultural runoff, deposition of nitrogen from burning fossil fuels, and human waste discharge has overfertilized the sea. Similar problems have created hypoxic areas in the northern Adriatic Sea, the Yellow Sea, and the Gulf of Thailand. Offshore fish farming is another growing source of nutrient buildup in some coastal waters.
Forty-three of the world's known dead zones occur in U.S. coastal waters. The one in the Gulf of Mexico, now the world's second largest, disrupts a highly productive fishery that provides some 18 percent of the U.S. annual catch. Gulf shrimpers and fishers have had to move outside of the hypoxic area to find fish and shrimp. Landings of brown shrimp, the most economically important seafood product from the Gulf, have fallen from the record high in 1990, with the annual lows corresponding to the highly hypoxic years.
Excess nutrients from fertilizer runoff transported by the Mississippi River are thought to be the primary cause of the Gulf of Mexico's dead zone. Each year some 1.6 million tons of nitrogen now enter the Gulf from the Mississippi basin, more than triple the average flux measured between 1955 and 1970. The Mississippi River drains 41 percent of the U.S. landmass, yet most of the nitrogen originates in fertilizer used in the productive Corn Belt.
Worldwide, annual fertilizer use has climbed to 145 million tons, a tenfold rise over the last half-century. (See data at  ) This coincides with the increase in the number of dead zones around the globe. And not only has more usable nitrogen been added to the environment each year, but nature's capacity to filter nutrients has been reduced as wetlands are drained and as areas along riverbanks are developed. Over the last century, the world has lost half its wetlands.
In the United States, some of the key farming states like Ohio, Indiana, Illinois, and Iowa have drained 80 percent of their wetlands. Louisiana, Mississippi, Arkansas, and Tennessee have lost over half of theirs. This lets even more of the excess fertilizer farmers apply flow down the Mississippi River to the gulf.
There is no one way to cure hypoxia, as the mix of contributing factors varies among locations. But the keys are to reduce nutrient pollution and to restore ecosystem functions. Fortunately, there are a few successes to point to. The Kattegat straight between Denmark and Sweden had been plagued with hypoxic conditions, plankton blooms, and fish kills since the 1970s. In 1986, the Norway lobster fishery collapsed, leading the Danish government to draw up an action plan. Since then, phosphorus levels in the water have been reduced by 80 percent, primarily by cutting emissions from wastewater treatment plants and industry. Combined with the reestablishment of coastal wetlands and reductions of fertilizer use by farmers, this has limited plankton growth and raised dissolved oxygen levels.
The dead zone on the northwestern shelf of the Black Sea peaked at 20,000 square kilometers in the 1980s. Largely because of the collapse of centralized economies in the region, phosphorus applications were cut by 60 percent and nitrogen use was halved in the Danube River watershed and fell similarly in other Black Sea river basins. As a result, the dead zone shrank. In 1996 it was absent for the first time in 23 years. Although farmers sharply reduced fertilizer use, crop yields did not suffer proportionately, suggesting they had been using too much fertilizer before.
While phosphorus appears to have been the main culprit in the Black Sea, nitrogen from atmospheric sources--namely, emissions from fossil fuel burning--seems to be the primary cause of the dead zones in the North and Baltic seas. Curbing fuel use through efficiency improvements, conservation, and a move toward renewable energy can diminish this cause of the problem.
For the Gulf of Mexico, curbing nitrogen runoff from farms can shrink the dead zone. Applying fertilizer to match crop needs more precisely would allow more nutrients to be taken up by plants instead of being washed out to sea. Preventing erosion through conservation tillage and changing crop rotations, along with wetland restoration and preservation, can also play a part.
Innovative programs such as the American Farmland Trust's Nutrient Best Management Practices Endorsement can reduce the common practice of using too much fertilizer. Farmers who follow recommendations for fertilizer application and cut their use are guaranteed financial coverage for potential shortfalls in crop yields. They save money on fertilizer purchases and are insured against losses. Under test programs in the United States, fertilizer use has dropped by a quarter.
With carefully set goals and management, it is possible for some dead zones to shrink in as little as a year. For other hypoxic areas (especially in the Baltic, a largely enclosed sea with slower nutrient turnover), improvement may take longer, pointing to the need for early action. For while dead zones shrink or grow depending on nutrient input and climatic conditions, the resulting fish dieoffs are not so easily reversed.
18 March 2004
A team of leading marine researchers has produced the first conclusive evidence to demonstrate the link between nutrient run-off and escalating crown-of-thorns starfish infestations in the Great Barrier Reef lagoon. The collaborative effort of CRC Reef scientists from the Australian Institute of Marine Science (AIMS), Dr Glenn De'ath, Dr Katharina Fabricius and Dr Ken Okaji, and from James Cook University (JCU), Mr Jon Brodie may end 40 years of intense scientific and community debate.
Many have feared the crown-of-thorns starfish plagues spelled the end of the reef and blamed human activity, while others argued that it is a natural phenomenon.
Water quality expert Mr Jon Brodie said the study shows an increase in nutrient run-off has led to higher levels of phytoplankton, which is food for the starfish larvae. “The levels of nutrients such as nitrate, ammonia and phosphate that run into rivers and out onto the Great Barrier Reef have spiralled since 1850, particularly near developed areas,” Mr Brodie said. “Cropping, grazing and urban development are responsible for the rise in nutrient levels,” he said.
Statistical modeller Dr Glenn De'ath said laboratory experiments reveal that twice as much phytoplankton results in a ten-fold increase in larval survival. “This increase in larval survival could stimulate a population explosion causing severe outbreaks of adult starfish,” he said. Dr De'ath said field surveys indicate that phytoplankton levels on reefs off the developed central Great Barrier Reef are double those north of Cooktown, where there is little human influence.
A computer model developed by Dr De'ath predicts that such a doubling of phytoplankton will create more frequent outbreaks, from one every 50-100 years to one every 15 years; frequencies consistent with those observed in the northern and central Great Barrier Reef. “The high frequency of outbreaks means the coral has less time to fully recover. In regions such as the far north, where conditions are relatively pristine, the models predict coral cover 2-4 times higher than in areas of the central region of the GBR where human influence is strong. These predictions agree with surveys of the two regions,” Dr De'ath said.
The scientists believe the research demonstrates that improved water quality will create greater coral cover and a healthier reef by reducing the frequency of crown-of-thorns starfish outbreaks.
Dr Glenn De'ath, Australian Institute of Marine Science on 07 4758 1979, firstname.lastname@example.org
Mr Jon Brodie, James Cook University, on 07 4781 6435, email@example.com
Ms Chloe Lucas, CRC Reef media liaison on 07 4729 8450 or 0408 884521, firstname.lastname@example.org
Ms Wendy Ellery, AIMS media liaison, on 07 4753 4409 email@example.com
Reader, please note that the link between plankton blooms and starfish larvae is plausible but not proven as a direct cause and effect relationship. An increase in plankton density benefits many organisms, such as the COTstar-predating Triton snail. Plankton blooms have many side effects, and our plankton balance hypothesis suggests that the increase in decomposing organisms in the water may be enough to explain coral deaths and the deaths of other organisms. In general, opportunistic short-lived species do better in plankton-rich waters than long-lived species. The last sentence, however, is true: Clean the water up and corals will recover and the Barrier Reef will be saved. Read about our most recent discoveries: www.seafriends.org.nz/decay/.
Geoffrey P. Jones *, Mark I. McCormick, Maya Srinivasan, and Janelle V. Eagle
School of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia
POPULATION BIOLOGY PNAS | May 25, 2004 | vol. 101 | no. 21 | 8251-8253
www.pnas.org/cgi/content/full/101/21/8251 free article in HTML
From 1996 to 2003, researchers documented a decline in coral cover from 66% to less than 7%. In conjunction with this decline was an observed decline in 75 % of the reef fish species, including 50% of reef species that declined to less than half of their original population densities.
From the free abstract
In the past, there has been a dichotomy of opinion over how closely fish communities are linked to their habitat, with some information indicating a high degree of variability that is independent of habitat change (9–14) and other data showing that coral-specialists clearly suffer when coral cover is reduced (13–17). Here we ask the following questions. If coral reefs continue along a path of degradation, what will be the fate of fish communities as a whole? Will marine reserves provide fish communities with any resilience to the effects of habitat loss?
"Although there is a large body of evidence that indicates that marine reserves can be an effective management strategy for protecting marine biodiversity (6–8), there is a growing recognition that such areas cannot protect reefs from large-scale pollution or global warming (4, 27–30). Thus, although marine reserves are necessary to control the "top-down" impact of human predation, they must be combined with management strategies that fundamentally address "bottom-up" processes that appear to be a more likely path to extinction."
In other words: marine reserves can't work where
The graph on left shows how in a period of 6-7 years coral cover declined six-fold and with it fish species richness by 15-20 %, regardless of whether the area was protected or not, but the marine reserve scores a slightly higher fish biodiversity.
The graph above shows species change ranked by those who increased most on left and those who decreased most on right, in a period of 5 years. The data shows that some species increased, whereas most decreased.
Author: Father Api and T. Goreau
Date: Tuesday, 2 May 2006
Greetings from Labasa in the Fiji Islands (Pacific), writes Father Api; I thank you and feel very moved to hear the stories about the Haida Nation and the British Virgin Islands. Fiji is now putting a lot of its effort into tourism. We have been warned about this recently by the University of the South Pacific. I really believe the land owners who allow their seashore to be built up with hotels and resorts must be made aware of the danger of sewage pollution and advised how to act to protect their environments. I come from a village opposite a hotel. One problem we are faced with is the sea that runs between the village and the hotel has stopped providing us with fresh sea food. Something has happened and I believe it’s something to do with the hotel. Fiji needs to be careful now, or else it will be too late.
For other islands, it may already be too late. Thomas Goreau writes
from Jamaica (Caribbean): Since early childhood, I watched all the reefs
of Jamaica killed by algae whose uncontrolled growth was caused by untreated
sewage. Waves of algae spread outwards from all the sewage sources over
a period of 40 years, as each part of the coast was developed, until all
of our reefs were smothered. Foreign experts came afterwards, did superficial
studies, and blamed the fishermen instead of sewage! The result of their
wrong diagnosis, based on faulty science and ignorance of local environmental
history, are proposals that cannot possibly work. They advise to create
marine protected areas and stop people from fishing and then the corals
and fish will thrive.
Yet these protected areas are full of dead and dying corals and the algae have not vanished! In fact, the only way to get rid of algae is to starve them, by cutting off the fertilizers and other nutrients pouring into the sea. When this is done the algae quickly die; I saw a bay in Jamaica cleaned up in only a few months this way. The only way to restore the fisheries is to restore the health of the coral reef habitat that maintains them, not to pretend that sick areas that are protected can support more fish. At the United Nations Experts Meeting on waste management in Small Island Developing States, I wrote the review chapter on the effects of land-based sources of nutrients (from detergents, sewage, fertilizers, pesticides and other sources) on coral reefs and fisheries. The problem can be solved by using biological tertiary treatment to recycle all the nutrients on land. In this way the productivity of the land can be improved, and we don’t poison the sea and kill our corals and fish. The entire group of experts called for complete elimination of all human caused sources of nutrients to the coastal zone and the sea. But this message was lost completely at the United Nations Summit for small islands in 2005, and has also been totally ignored in the Small Island State Position Paper for the forthcoming United Nations Commission on Sustainable Development meetings on energy and environment. All the key points have been dropped. It seems that we do not want to learn from our experience. If so, we only have ourselves to blame.
With permisssion: SMALL ISLANDS VOICE [newsletter] Small Islands Voice
Global Internet Forum (www.sivglobal.org)
Coral reefs in the Caribbean have suffered significant changes due to the proximal effects of a growing human population, reports a new study.
"It is well acknowledged that coral reefs are declining worldwide but the driving forces remain hotly debated," said author Camilo Mora at Dalhousie University, Halifax, Canada. "In the Caribbean alone, these losses are endangering a large number of species, from corals to sharks, and jeopardizing over 4 billion dollars in services worth from fisheries, tourism and coastal protection," he added.
"The continuing degradation of coral reefs may be soon beyond repair, if threats are not identified and rapidly controlled," Mora said. "This new study moves from the traditional localized study of threats to a region-wide scale, while simultaneously analyzing contrasting socioeconomic and environmental variables," he added.
The study monitored coral reefs, including corals, fishes and macroalgae, in 322 sites across 13 countries throughout the Caribbean. The study was complemented with a comprehensive set of socioeconomic databases on human population density, coastal development, agricultural land use and environmental and ecological databases, which included temperature, hurricanes, productivity, coral diseases and richness of corals. The data were analyzed with robust statistical approaches to reveal the causes of coral reef degradation in that region.
The study showed clearly that the number of people living in close proximity to coral reefs is the main driver of the mortality of corals, loss of fish biomass and increases in macroalgae abundance. A comparative analysis of different human impacts revealed that coastal development, which increases the amount of sewage and fishing pressure (by facilitating the storage and export of fishing products) was mainly responsible for the mortality of corals and loss of fish biomass.
Additionally, the area of cultivated land (a likely surrogate for agrochemical discharges to coral reefs) was the main driver of increases in macroalgae. Coral mortality was further accelerated by warmer temperatures.
"The human expansion in coastal areas inevitably poses severe risks to the maintenance of complex ecosystems such as coral reefs," Mora said. "On one hand, coral reefs are maintained due to intricate ecological interactions among groups of organisms. For instance, predators prey upon herbivorous, herbivores graze on macroalgae, and macroalgae and corals interact for their use of hard substrata. Given the intensity of these interactions the effects of a threat in anyone group may escalate to the entire ecosystem. On the other hand, the array of human stressors arising from changes in land use, exploitation of natural resources and increases in ocean temperature (and perhaps acidification) due to an increasing demand for energy, are significantly affecting all major groups of coral reef organisms. The simultaneous effect of human threats on coral reef organisms and the potential escalation of their effects to the entire ecosystem highlight the critical situation of coral reefs and the need to adopt an ecosystem-based approach for conservation and an integrated control of multiple human stressors," he added.
The study also showed that the effective compliance of fishing regulations inside Marine Protected Areas (MPAs) has been successful in protecting fish populations. But coral mortality and macroalgae abundance showed no response to the presence of MPAs. That was explained by the general failure of MPAs in the Caribbean to account for threats such as land runoffs and ocean warming. "Unfortunately, the degradation of the coral reef matrix inside MPAs may, in the long term, defeat their positive effect on fish populations," Mora said. "This further highlights the need for a holistic control of human stressors," he added.
"The future of coral reefs in the Caribbean and the services they provide to a growing human population depend on how soon countries in the region become seriously committed to regulating human threats", Mora said. "Although coral reefs will experience benefits of controlling fishing, agricultural expansion, sewage or ocean warming, it is clear that underlying all these threats is the human population. The expected increase of the world's human population from 6 billion today to 9 billion for the year 2050 suggests that coral reefs are likely to witness a significant ecological crisis in the coming half century if effective conservation strategies, including policies on population planning, are not implemented soon," he added.
This research is published in the Proceedings of the Royal Society of
From the paper:
... While the effective implementation of marine protected areas (MPAs) increased the biomass of fish populations, coral reef builders and macroalgae followed patterns of change independent of MPAs. ...
The study looked at measurable factors: hurricanes, chlorophyll (green sea), thermal stress, average temperature, coral disease, urchin density, coral species, MPA effectiveness, coastal development, cultivated land and human density. It found that the last three were related and caused most of the degradation. Urchins increased in degraded environments. Note that the study was an exercise in statistics.
The scientists were unable to identify the very cause of coral decay. Listen to this: "Our argument to explain this result is as follows. It has been found that herbivores may not be able to cope with increases in macroalgae beyond a given threshold of macroalgae coverage (see Williams & Polunin 2001). For the Caribbean, increasing coral mortality (e.g. Gardner et al. 2003) has probably opened large areas of substrate for algae growth, which may be surpassing the threshold of herbivory control."
"The expected increase in human population from 6 billion people today to 9 billion for the year 2050 (Cohen 2003) and a probable 1.8–48C temperature increase over the same time period (IPCC 2007) suggest that coral reefs are likely to witness a significant ecological crisis in the coming half century. Fortunately, the solutions are already available, which include the use of enforced no-take MPAs definitely complemented with strategies to regulate the effects of land use and international commitment to reduce the emission of Causes of coral reef degradation greenhouse gases, and finally the implementation of strategies to reduce or stabilize the ultimate cause of all these stressors, the world’s human population." [sigh]
[note! the graph of coral decline in Jamaica is not from this publication but it shows how serious the situation is]
Term Region-Wide Declines in Caribbean Corals
Toby A. Gardner,1,3 Isabelle M. Côté,1* Jennifer A. Gill,1,2,3 Alastair Grant,2 Andrew R. Watkinson1,2,3
Science 15 August 2003: Vol. 301. no. 5635, pp. 958 - 960 DOI: 10.1126/science.1086050
We report a massive region-wide decline of corals across the entire
Caribbean basin, with the average hard coral cover on reefs being reduced
by 80%, from about 50% to 10% cover, in three decades. Our meta-analysis
shows that patterns of change in coral cover are variable across time periods
but largely consistent across subregions, suggesting that local causes
have operated with some degree of synchrony on a region-wide scale. Although
the rate of coral loss has slowed in the past decade compared to the 1980s,
significant declines are persisting. The ability of Caribbean coral reefs
to cope with future local and global environmental change may be irretrievably
Coral community decline at a remote Caribbean island:
marine no-take reserves are not enough
Vânia R. Coelho, Carrie Manfrino
Aquatic Conservation: Marine and Freshwater Ecosystems; Volume 17 Issue 7, Pages 666 - 685
Published Online: 28 Feb 2007