Beware an ecological tsunami

Beware an ecological tsunami


describes the growing crisis of the oceans, and calls
for a full international scientific assessment

men fishing

Water defines our planet; the oceans dominate it. But because humans are terrestrial creatures and because until recently our impact has been relatively minor, we are largely ignorant of the essential roles of the oceans, the escalating changes in the marine realm and the possible consequences for all life on Earth. The explosive growth of the human population, our unsustainable use of resources and generation of wastes, and the increasing inequity within and among nations are resulting in profound changes to the oceans. A more enlightened understanding of these changes and their possible consequences is needed.

It is time to move beyond the outdated assumptions that the oceans have unlimited potential to provide food and assimilate wastes, beyond the myopic focus on short-term economic gains, beyond the primary preoccupation with the goods obtained from marine ecosystems, and beyond the indifferent acceptance of ignorance about oceanic patterns and processes. It is time to think more holistically about ocean ecosystems, and to consider more responsible ways in which humans can minimize their impact on the very systems that provide for our well-being. It is time to take better stock of our treasures before they are swept away in an ecological tsunami of unprecedented proportions.

The oceans are rich beyond imagining. The plants, animals and microbes at and below the surface are wondrously diverse, exotic and marvellous. They represent phenomenal diversity - diversity of body plans, diversity of ways of making a living, diversity of sensory structures, diversity of life histories, diversity of ecological interactions, diversity of chemicals and diversity of genetic material.

We are only beginning to discover much of the richness, partly because the variety (the result of billions of years of evolution) is so great, partly because exploring it has lagged behind terrestrial investigations and partly because many of the habitats are inaccessible. The descriptions 'salty' and 'wet' hardly do justice to the broad range of habitats which make up the ocean realm - from the more familiar nearshore coral reefs, kelp forests, sandy beaches, rocky shores, bays, estuaries, mangroves and salt marshes to the more exotic open oceans, continental shelves, abyssal plains, deep sea canyons, sea mounts, hot and cold vents, ice shelves - and more. The living organisms interact with each other and with their environment in dynamic ecosystems from polar to tropical waters, from the photic zone to the lightless depths.

Goods and services

People have relied for millennia on the useful goods produced by marine ecosystems. Food, fibre, shells, medicines, chemicals - and now genes - are extracted, used, bartered and sold around the world. These 'ecosystem goods' have been the prime focus of the economic value and 'usefulness' of marine ecosystems. But the oceans also produce a suite of essential 'ecosystem services' so far less appreciated, but no less essential.

These services range from producing oxygen and influencing climate, through both carbon and sulphur cycles, to creating the habitat that other species need to survive. Kelp forests, mangroves and coral reefs provide homes for rich assemblages of coastal organisms and protect shores from erosion by waves. Oysters in bays filter water; mangroves and salt marshes detoxify pollutants and collect sediment which could otherwise smother animals and plants downstream. These services are the product of the functioning of the ecosystem, the result of the characteristics of species, interactions among them and interactions between the organisms and the physical and chemical environment.

Together with ecosystem goods, these ecosystem services provide the marine component of the life support systems of planet Earth. Both are being threatened as genetic diversity is diminished, populations are fragmented, species are lost and ecosystems disrupted. Loss of species, fewer individuals of critical species, changes in their spatial configuration, size or strength of interaction with other species can all contribute to changes in the functioning of the system.

The causes of these changes are multiple and complex. They include overfishing (including by-catches and waste), chemical pollution, eutrophication, habitat degradation or destruction (from trampling, trawling, dredging, drilling, dynamiting, building, dumping and noise) and the introduction of exotic species. Climate change and increases of UV-B radiation as a result of stratospheric ozone depletion pose additional hazards. Most waters are affected by many of these stresses, some by all of them.

Ecosystems in trouble

There are clear signals from around the planet that these activities are resulting in serious problems. The demise of many of the world's fisheries has received widespread attention - but the declines of non-commercial species of seaweeds, shellfish and fishes gleaned from shores around the world for local use are equally serious. Unexpected, dramatic mass mortalities of many marine species have been reported - ranging from marine mammal die-offs and fish kills to mass mortalities of sea urchins, abalone, seagrasses and others.

coral fish The incidence of the bleaching of coral reefs appears to be increasing. Water quality is seriously impaired in coastal regions: in many places this represents a critical hazard to human health. Increases in rubbish, especially plastics, are obvious to almost everyone who frequents the shore. There have been many reports of increases in the frequency, intensity and spatial extent of harmful algal blooms such as red tides; with consequences ranging from human health hazards such as paralytic shellfish poisoning to aquacultural die-offs and increased mortality of fishes and marine mammals. The symptoms vary from place to place. Some are well documented, others less so. The actual causal factors are often ambiguous. Nonetheless, on the whole, the picture is one of marine ecosystems in trouble, especially in nearshore waters.

The vast majority of people on Earth live within 80 kilometres of the coast. Nearshore habitats bear the brunt of both land-based and sea-based activities: tourism, recreation, fishing, mariculture, domestic and industrial waste disposal, military activities, and the transportation, mining and energy industries. As a result, bays, estuaries, enclosed seas and coral reefs provide ample evidence of a plethora of problems. Many of these systems, especially coral reefs, estuaries, kelp forests and rocky shores are among the most productive systems on Earth; coastal waters produce 75 per cent of the world's fish catch. A higher priority must be put on ensuring their sustainability.

A crisis of unprecedented complexity

The old adage 'dilution is the solution to pollution' captures the historical attitudes toward oceans as vast, bountiful and infinitely resilient. The many problems occurring around the world suggest this is grossly misplaced. We are learning that the oceans, especially coastal areas, are under increasing and serious threat from multiple sources. We do not yet know the full extent of the problems, but marine scientists are in strong agreement that we are faced with a crisis of unprecedented complexity, proportions and consequences. The magnitude, kind and rate of change are startling. Making predictions about the likely outcomes of different possible management or policy options is extremely difficult. This uncertainty, coupled with incomplete baseline information about many systems, presents enormous challenges. The future undoubtedly holds surprises.

Decisions by society about land-use practices which affect the oceans and about uses of marine biota and habitats will be at their most powerful if they are informed by the best possible scientific understanding. In some cases, we have sufficient information to manage our activities more wisely, i.e., with significantly less impact - but though known, this information is often not used or communicated. In other cases, information urgently needs to be obtained by research and adaptive management. New mechanisms are needed to disseminate scientific knowledge more efficiently and effectively and to utilize it more appropriately.

A comprehensive, international scientific assessment such as that conducted by the Intergovernmental Panel on Climate Change or the Global Biodiversity Assessment would be one effective mechanism. Such policy-relevant assessments, conducted by outstanding scientists, provide a mechanism for communicating scientific consensus, level of certainty and verdicts on the likely consequences of different policy options. An international scientific assessment of the state of the world's oceans is both timely and essential. An evaluation of which problems are most serious, where each is most urgent, how they interact and potential remedial actions would prove useful.

Humans depend upon the life-support systems provided by the oceans. A sustainable biosphere requires a living ocean. It is time for a substantially different approach to thinking about and managing both the land-based and sea-based activities that currently threaten our oceans. The seas can no longer be a marginal issue.

Jane Lubchenco, Valley Professor of Marine Biology and Distinguished Professor at Oregon State University is President of the American Association for the Advancement of Science and Past President of the Ecological Society of America. She was on the steering committee of last year's Revelation and the Environment symposium.

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