Navigation Links
Rats on islands disrupt ecosystems from land to sea, researchers find
Date:2/25/2008

SANTA CRUZ, CA--Seabird colonies on islands are highly vulnerable to introduced rats, which find the ground-nesting birds to be easy prey. But the ecological impacts of rats on islands extend far beyond seabird nesting colonies, according to a new study by researchers at the University of California, Santa Cruz.

The study, which will be published the week of February 25, 2008, in the Proceedings of the National Academy of Sciences, has already helped make the case for the first major rat eradication effort in the Aleutian Islands. Planned to begin this summer, the project will target rats on the appropriately named Rat Island.

The UCSC researchers found that the presence of rats on islands in the Aleutian Archipelago dramatically alters the intertidal zone, reducing the amount of seaweed and increasing the numbers of snails, barnacles, and other invertebrates. These changes result from the decimation of seabird populations by the rats, according to graduate student Carolyn Kurle, who led the study.

"When you're on an island with rats, there are so few birds it's silent, in contrast to the cacophony on the islands without rats," Kurle said.

Some of the affected birds--sea gulls and oystercatchers, in particular--are major predators of invertebrates in the intertidal zone. In their absence, the snails, limpets, and other grazers increase in abundance, eat more algae, and clear more space for other invertebrates to settle and grow. The result is a shoreline practically stripped bare of the usual cover of fleshy algae (i.e., seaweed).

"Where there are no rats, we found plenty of birds, fewer invertebrates, and a lot more algal cover," Kurle said.

Kurle's coauthors are associate professor Donald Croll and assistant adjunct professor Bernie Tershy of UCSC's Department of Ecology and Evolutionary Biology. Croll and Tershy are also the cofounders of Island Conservation, a nonprofit organization dedicated to the protection and restoration of island ecosystems. For the Aleutian Island rat eradication project, Island Conservation has teamed up with the Nature Conservancy and the U.S. Fish and Wildlife Service.

"Our research is giving us a better understanding of the impacts of introduced rats, and by working directly with government agencies and nongovernmental organizations we're able to do something about it," Croll said.

The study describes an elegant example of an ecological phenomenon known as a trophic cascade. "In a trophic cascade, you have an apex predator--in this case, the rat--and because of what that predator eats, you get a cascade of effects that go down through lower levels of the food chain," Kurle said. "This is a clear example of a trophic cascade that crosses between terrestrial and marine ecosystems."

Kurle spent three summers conducting intertidal surveys on 32 islands in the Aleutian Archipelago--17 with rats and 15 without. At first, camping on rat-infested islands was disconcerting, she said. She had to wear ear plugs the first few nights because the sound of rats rustling around outside the tent was keeping her awake. But she soon got used to it.

"We had to be careful with food and trash, but they never got into the tent or anything," Kurle said. "They come out as soon as it starts to get dark, and we would see them running around everywhere. We spent several nights watching them through night-vision binoculars."

The researchers found large numbers of dead birds partially eaten by rats on the islands. The rats mainly attack the chicks, but may also go after adults, Kurle said. Very few birds manage to breed successfully on the rat-infested islands.

Another recent paper from Croll and Tershy's group provides a global overview of the direct effects of invasive rats on seabirds. Published in the February issue of Conservation Biology, the paper reviews the findings of 94 published studies. First author Holly Jones was an intern with Island Conservation as an undergraduate at UCSC and is now a graduate student at Yale University. Coauthors include Croll, Tershy, and Erika Zavaleta, assistant professor of environmental studies at UCSC.

"This is a large-scale analysis showing that rats have preyed on 75 species of seabirds in 10 families on islands throughout the world. The hardest hit seabirds are the small, hole-nesting species like petrels and auklets," Croll said.

The good news is that rats can be eradicated from islands. Island Conservation has led successful eradication efforts on islands off the coast of Mexico and on Anacapa Island, one of the Channel Islands off southern California, Croll said. Worldwide, rats have been removed from more than 274 islands, according to the Nature Conservancy.

"It's been done many times," Croll said. "What's interesting is the synergy between the research and the conservation efforts. Academic researchers tend to do studies and publish them, and then nothing happens. So it's very exciting for our students to see that their research can tie in directly with the conservation mission of a large organization like the Nature Conservancy."


'/>"/>

Contact: Tim Stephens
stephens@ucsc.edu
831-459-2495
University of California - Santa Cruz
Source:Eurekalert

Related biology news :

1. First wind turbines on Galapagos Islands will halve diesel imports, reduce risk of future oil spills
2. Disrupting common parasites ability to talk to each other reduces infection
3. Climate gas could disrupt food chain
4. City birds better than rural species in coping with human disruption
5. Adapting local ecosystems can soften impact of global climate change
6. Map is first to track global human influences on ocean ecosystems
7. First map of threats to marine ecosystems shows all the worlds oceans are affected
8. Resilience concepts poised to aid management of coastal marine ecosystems
9. At the root of nutrient limitation, ecosystems are not as different as they seem
10. Genetically engineered corn may harm stream ecosystems
11. Study shows genetically engineered corn could affect aquatic ecosystems
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/4/2017)... , Oct. 4, 2017  GCE Solutions, a global clinical ... data and document anonymization solution on October 4, 2017. Shadow is ... field to comply with policy 0070 of the European Medicines Agency ... data. ... GCE Solutions ...
(Date:6/30/2017)... , June 30, 2017 Today, ... developer and supplier of face and eye tracking ... Featured Product provider program. "Artificial ... innovative way to monitor a driver,s attentiveness levels ... from being able to detect fatigue and prevent ...
(Date:5/16/2017)... TEANECK, N.J. , May 16, 2017  Veratad ... leading provider of online age and identity verification solutions, ... the K(NO)W Identity Conference 2017, May 15 thru May ... Ronald Regan Building and International Trade Center. ... across the globe and in today,s quickly evolving digital ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... October 12, 2017 , ... BioMedGPS announces expanded coverage of ... newest module, US Hemostats & Sealants. , SmartTRAK’s US Market for Hemostats and ... synthetic sealants and biologic sealants used in surgical applications. BioMedGPS estimates the market ...
(Date:10/11/2017)... ... October 11, 2017 , ... ... its endogenous context, enabling overexpression experiments and avoiding the use of exogenous expression ... guides is transformative for performing systematic gain-of-function studies. , This complement to ...
(Date:10/11/2017)... BioMarketing, a leading provider of patient support solutions, has announced ... network, which will launch this week. The VMS CNEs will ... to enhance the patient care experience by delivering peer-to-peer education ... professionals to help women who have been diagnosed and are ... ...
(Date:10/11/2017)... ... October 11, 2017 , ... Singh ... orphan drug designation to SBT-100, its novel anti-STAT3 (Signal Transducer and Activator of ... SBT-100 is able to cross the cell membrane and bind intracellular STAT3 and ...
Breaking Biology Technology: