Scientists warn of marine ecosystem collapse
'Every species counts' is the key message from an international report on marine biodiversity. Threats to some species are seriously threatening oceans' ability to produce seafood, resist diseases, filter pollutants and recover from stresses such as over-fishing and climate change, scientists concluded at the end of a four-year study. The study, published in the journal Science, reveals how every species lost causes a faster unravelling of the overall ecosystem. More encouragingly, the study found that every species recovered adds significantly to the ecosystem's overall productivity and stability, as well as its ability to withstand stresses. 'Whether we looked at tide pools or studies over the entire world's ocean, we saw the same picture emerging, said project leader Boris Worm from Dalhousie University in Canada. 'In losing species we lose the productivity and stability of entire ecosystems. I was shocked and disturbed by how consistent these trends are - beyond anything we suspected.' It is not only each species of fish that is essential for the survival of others - fish rely on clean water, prey populations and diverse habitats. The scientists therefore recommend moving away from single species management, and towards global species management. 'Unless we fundamentally change the way we manage all the oceans' species together, as working ecosystems, then this century is the last century of wild seafood,' warned co-author Steve Palumbi of Stanford University in the US. Indeed, the report claims that by 2048, stocks of all the species currently fished for food will collapse to less than 10% of the maximum catches recorded. This would not only make fishing impossible, but would render stocks unlikely to recover. Not only will oceans produce less seafood, but what remains could pose a threat to human health as ecosystems become vulnerable to invasive species, disease outbreaks and noxious algal blooms. At present there is no international agreement to prevent overfishing. EU Member States must follow catch limits set by the common fisheries policy, but other countries set their own quotas. There is still time to reverse the damage done, according to Dr Worm: 'We can turn this around. But less than 1% of the global ocean is effectively protected right now. We won't see complete recovery in one year, but in many cases species come back more quickly than people anticipated - in three to five to 10 years. And where this has been done we see immediate economic benefits.' The study brought together teams from Canada, Sweden, the UK, the US and the Republic of Panama. The scientists analysed 32 controlled experiments, observational studies from 48 marine protected areas, and global catch data from the UN's Food and Agriculture Organisation (FAO) database.
Countries
Canada, Sweden, United Kingdom, United States