Venezuela: taking one fish species away changes environment


Flannelmouth characinFrom Dartmouth College (USA):

Researchers at Dartmouth, Cornell University, and the University of Wyoming have learned that the removal of just one important species in a freshwater ecosystem can seriously disrupt how that environment functions.

This finding contradicts earlier notions that other species can jump in and compensate for the loss.

Brad Taylor, currently a research associate in the department of biological sciences at Dartmouth, and his colleagues studied a fish called the flannelmouth characin (Prochilodus mariae) native to South American rivers.

This particular fish eats detritus, the fine organic matter on the river bottom, and because of this, it plays a critical role in regulating the breakdown and transport of carbon in the rivers.

“This fish species is a popular food source; it is harvested regularly, and in some cases, it’s overfished,” says Taylor, the lead author on the study that was published in the August 11 issue of the journal Science.

“We learned that removing this particular fish greatly altered the metabolic activity of the river ecosystem.

Other fish species did not compensate for the lack of Prochilodus, an effect consistent with observations from other rivers where they have been excluded much longer by dams.”

The researchers used a heavy, plastic divider to split a 210-meter stretch (a little more than a tenth of a mile) of Rio Las Marías in Venezuela into two separate river sections.

On one side, they removed only Prochilodus, and on the other, all the fish remained.

The team then took a series of measurements upstream and downstream to quantify the transport of particulate organic carbon (POC).

“Although there are more than 80 fish species in this small river, the detritivores, like Prochilodus, make up 50-80 percent of the fish biomass.

Their abundance makes them attractive targets for harvesting by people.

So when we took them away, not only was the impact astounding, it also revealed how their loss could change carbon flow, an important measure of ecosystem function,” says Taylor.

1 thought on “Venezuela: taking one fish species away changes environment

  1. Pingback: Piranha and other new fish species discovered in Venezuela | Dear Kitty. Some blog

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