World’s reef fish systems threatened by human overpopulation

April 6th, 2011 - 6:44 pm ICT by ANI  

National Geographic Washington, April 6 (ANI): A new study has found that the highly diverse reef fish systems are the most vulnerable to human threats.

In a large collaborative analysis, 55 scientists from 49 nations demonstrated that the ability of reef fish systems to produce goods and services to humanity increases rapidly with the number of species.

However, growing human populations are hampering the ability of reefs to function normally, and counter intuitively, the most diverse reef fish systems suffer the greatest impairments from stressors triggered by human populations.

The study documented that the extent of this distress is widespread and likely to worsen because 75 percent of the world`s reefs are near human settlements and because around 82 percent of the tropical countries with coral reefs could double their human populations within the next 50 to 100 years.

The two year study was initiated to collect the necessary data to determine if biodiversity influences the functioning of reef fish systems, and if so, elucidate the role of humans in such a linkage.

The team collected demographic data on human populations as well as environmental and biological data on the identity of species, their abundances and body sizes in almost 2,000 coral reef locations worldwide.

These data were used to calculate the cumulative weight of all fishes on each reef (also called standing biomass), which is one of the main services reef fishes provide to humanity through food supply but also a very close proxy for how effectively ecosystems produce biomass.

“The results of the study were stunning,” said co-author Kevin Gaston at Sheffield University.

“While experimental studies have elucidated that the biomass production of ecosystems stabilizes after a certain number of species is reached, this field study demonstrated that the production of biomass in reef fish systems did not saturate with the addition of new species,” he added.

“This study shows, quite simply, that the more biodiversity, the better. The benefits appear limitless, if we allow ecosystems to operate at their full potential,” said co-author Marah Hardt.

The study also demonstrated that standing biomass reduced with increasing human density, although for the same number of people the reduction of biomass was significantly larger in more diverse ecosystems.

“Coral reefs are the most diverse ecosystem on the planet, hosting thousands of species and generating numerous goods and services to millions of people worldwide,” said Enric Sala, a National Geographic fellow and co-author of the study.

“The future of coral reefs and the services they provide to a growing human population depend on how soon countries become seriously committed to regulating human threats,” she added.

The findings are detailed in the journal PLoS Biology. (ANI)

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