Demise of deep-sea species could lead to collapse of ocean ecosystems

Demise of deep-sea species could lead to collapse of ocean ecosystems

mongabay.com

December 27, 2007

Declining populations of deep-sea species pose a significant threat to the health of world oceans, warns a study published in the January 8th issue of Current Biology.

Analyzing the biodiversity of nematode worms and other indicators of ecosystem functioning and efficiency at 116 deep-sea sites, a team of researchers lead by Roberto Danovaro of Italy’s Polytechnic University of Marche found evidence that the health of the deep sea increases exponentially with the diversity of species living there.

“For the first time, we have demonstrated that deep-sea ecosystem functioning is closely dependent upon the number of species inhabiting the ocean floor,” explained Danovaro. “This shows that we need to preserve biodiversity, and especially deep-sea biodiversity, because otherwise the negative consequences could be unprecedented. We must care about species that are far from us and [essentially] invisible.”

Danovaro says that “ecosystem functioning involves several processes, which can be summarized as the production, consumption, and transfer of organic matter to higher levels of the food chain, the decomposition of organic matter, and the regeneration of nutrients,” according to a release from Cell Press, publisher of Current Biology.

Danovaro’s team chose nematode worms as a proxy for deep-sea biodiversity because they account for more than 90% of all life on the sea floor.

The researchers “found that sites with a higher diversity of nematodes support exponentially higher rates of ecosystem processes and an increased efficiency with which those processes are performed,” stated the release from Cell Press. “Efficiency reflects the ability of an ecosystem to exploit the available energy in the form of food sources.”

“Our results suggest that a higher biodiversity can enhance the ability of deep-sea benthic systems to perform the key biological and biogeochemical processes that are crucial for their sustainable functioning,” said the researchers.

“Deep-sea ecosystems provide goods (including biomass, bioactive molecules, oil, gas, and minerals) and services (climate regulation, nutrient regeneration and supply to the [upper ocean], and food) and, for their profound involvement in global biogeochemical and ecological processes, are essential for the sustainable functioning of our biosphere and for human wellbeing,” the authors concluded. “Our results suggest that the conservation of deep-sea biodiversity can be crucial for the sustainability of the functions of the largest ecosystem” on the planet.

Deep-sea ecosystems are increasingly affected by trawling and commercial fishing activities. Scientists fear that increasing ocean acidity — driven by anthropogenic emissions of carbon dioxide — may adversely impact the microorganisms that form the basis for the marine food chain.

This article is based on a news release from Cell Press.