Single Fish Species Controls Health Of Tropical River

Scientists have discovered that removing just one fish species from a tropical river can have deleterious effects. This contradicts the till now held belief that the greater abundance and diversity of other species would compensate for the loss. Researchers removed the flannelmouth fish (Prochilodus mariae) from a stretch of Venezuela's Orinoco River and measured how this affected the level of carbon in the ecosystem. The researchers found that the river's carbon cycle was disrupted within 48 hours of them removing the fish. The effect lasted for at least 40 days. The amount of organic carbon on the riverbed rose by 450 per cent. Full details appear in Science today (11 August).