Navigation Links
Fish extinctions alter critical nutrients in water, study shows

Ecosystems are such intricate webs of connections that few studies have been able to explore exactly what happens when a species dies out.

Now, a Cornell study using computer simulations has teased out how the disappearance of a freshwater fish can affect the availability of certain nutrients that other species rely on.

Algae, at the base of the food chain, for example, rely on fish to cycle back into the water such nutrients as nitrogen and phosphorus, which are otherwise locked up in animal or plant cells. Fish excrete dissolved nutrients back into the water, making them available to algae, which need them to grow.

The study, published in the Feb. 27 issue of the Proceedings of the National Academy of Sciences, finds that overfishing could threaten the overall health of an ecosystem because it targets important fish species that play major roles in recycling nutrients. In fact, 20 percent of fish species accounted for more than half of all the recycled nutrients in the ecosystems studied, the computer simulations found.

"The loss of the most heavily fished species led to the fastest declines in nutrient recycling," said lead author Peter McIntyre, a postdoctoral researcher at Wright State University who was a graduate student in Cornell's Department of Ecology and Evolutionary Biology when he conducted the study. "Fishermen are targeting relatively large and abundant species that happen to play a major role in nutrient recycling."

The simulations, which relied on data from Rio Las Marias, a Venezeulan river, and Lake Tanganyika, a massive lake bordering Tanzania, Zaire, Zambia and Burundi, also shed light on the roles that surviving species might play in replacing the lost nutrients. In both ecosystems studied, when surviving species successfully picked up the slack in nutrient recycling left by an extinct species, nitrogen and phosphorus were maintained at 80 percent of their starting values until over half the total num ber of species were lost.

Studies of complex ecosystems, especially those involving large, highly mobile fish, are almost impossible to carry out in the wild, but new methods are helping researchers better understand these systems.

"Computer simulations provide a means to assess patterns of species loss in a system in which we just cannot do complex experiments," said co-author Alex Flecker, Cornell associate professor of ecology and evolutionary biology, who served as McIntyre's adviser. "But we have to be aware that there is a whole set of assumptions that goes into simulating species loss."

For example, it is unknown whether surviving species can truly compensate for extinctions. In a study of two species of fish in the Venezuelan river that eat mud from the river bottom, Flecker found that the rarer of the two species was unable to make up for the loss of the more common one. Thus, it appears that human overfishing of the common species, coporo (Prochilodus mariae), may have large effects on the ecosystem, in part because of its large contribution to nitrogen recycling.

The current study also revealed that species that heavily recycle nitrogen are not always the same ones that recycle the most phosphorus. These differences would make it difficult for conservationists to prioritize species to protect.

Source:Cornell University News Service

Related biology news :

1. Super predators and mass extinctions
2. New study pinpoints epicenters of Earths imminent extinctions
3. Climate change drives widespread amphibian extinctions
4. Man may have caused pre-historic extinctions
5. Birth rate, competition are major players in hominid extinctions
6. Improved predictions of warming-induced extinctions sought
7. Products containing specific probes for detecting alternative splice forms protected
8. Compounds in plastic packaging act as environmental estrogens altering breast genes
9. Plant pathologists evaluate eco-friendly alternatives to methyl bromide
10. New technique could alter field of mouse genetics
11. Genetic variation alters response to common anti-clotting drug

Post Your Comments:

(Date:6/7/2016)... 7, 2016  Syngrafii Inc. and San Antonio ... that includes integrating Syngrafii,s patented LongPen™ eSignature "Wet" ... collaboration will result in greater convenience for SACU ... while maintaining existing document workflow and compliance requirements. ... Highlights: ...
(Date:6/2/2016)...   The Weather Company , an IBM Business (NYSE: ... capability in which consumers will be able to interact with ... via voice or text and receive relevant information about the ... Marketers have long sought an advertising solution that can create ... relevant and valuable; and can scale across millions of interactions ...
(Date:5/24/2016)... May 24, 2016 Ampronix facilitates superior patient care by providing unparalleled technology ... LCD display is the latest premium product recently added to the range of products ... ... ... 3d Imaging- LCD Medical Display- Ampronix News ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... (PRWEB) , ... June 23, 2016 , ... STACS DNA ... Technical Leader at the Arkansas State Crime Laboratory, has joined STACS DNA as a ... STACS DNA team,” said Jocelyn Tremblay, President and COO of STACS DNA. “In further ...
(Date:6/23/2016)... , June 23, 2016 Apellis ... Phase 1 clinical trials of its complement C3 ... single and multiple ascending dose studies designed to ... (PD) of subcutaneous injection in healthy adult volunteers. ... (SC) either as a single dose (ranging from ...
(Date:6/23/2016)... , June 23, 2016 ... Hematology Review, 2016;12(1):22-8 ... , the peer-reviewed journal from touchONCOLOGY, Andrew ... escalating cost of cancer care is placing an ... result of expensive biologic therapies. With the patents ...
(Date:6/23/2016)... ... June 23, 2016 , ... ClinCapture, the only free ... and will showcase its product’s latest features from June 26 to June 30, ... poster on Disrupting Clinical Trials in The Cloud during the conference. DIA ...
Breaking Biology Technology: