Declining Fish Population has Broad Ecological Consequences
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A perfect example of why biodiversity is so important, and our interconnectedness to all things, even an obscure, uncharasmatic fish species in a river in South America. From Newswise: “Dramatic population reductions of a single fish species in a South American river could degrade ecosystem function in an entire river system.”
Dramatic population reductions of a single fish species in a South American river could degrade ecosystem function in an entire river system, according to an article in the Aug. 11 issue of the journal Science.
The authors, Brad W. Taylor and Robert O. Hall Jr. of the University of Wyoming, and Cornell University’s Alexander S. Flecker, studied the ecological consequences resulting from overfishing of the flannelmouth characin, a migratory species in Rio Las Marias, one of several Andean piedmont rivers in Venezuela’s Orinoco Basin. They discuss their results in the article, “Loss of a Harvested Fish Species Disrupts Carbon Flow in a Diverse Tropical River.” …
The researchers report, “Size-selective harvesting may have long-lasting negative feedbacks on fish populations, ecosystem function, and the flow of protein to humans and other animals, eroding an important ecosystem service.”
These fish, which feed on particles deposited on the stream bottom, play a significant role in carbon flow and nutrient cycling, Taylor says. As the fish feed, they stir up, consume and egest large amounts of dissolved and particulate nutrients. The researchers say these processes are important for nutrient transport and the flow of carbon through the ecosystem, especially during the dry season when transport by floods is reduced. The researchers discovered that during a six-year period, larger migrations of the flannelmouth characin were associated with greater downstream transport of organic carbon, which is an important energy and nutrient source to downstream ecosystems.
They also identified another adverse consequence of the species decline. The bottom-feeding fish remove organic matter that shades nitrogen-fixing algae. When the fish were taken out, bacterial respiration increased, so more organic carbon was consumed and converted to carbon dioxide by bacteria rather than being transported downstream and more evenly distributed among organisms.
“The loss or decline of this fish species could extend throughout the stream network and food web, affecting populations algae, bacteria, insects and other fish species,” says Taylor.
budak said,
August 15, 2006 at 10:28 pm
Even among the local aquarist circles I frequent, dismally few hobbyists have a clue about which species are native, feral or foreign. To them, a fish is a fish is a fish is a fish (substitute fish for tree, flower, bird or another other organism).
Maisy said,
October 14, 2007 at 9:05 pm
Yet another reason why everyone should go vegan!!