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March 23, 1998

NOAA funds studies by UCSC scientists on the effects of El Nino

By Francine Tyler

Two UCSC research teams have received grants totaling $142,000 from the National Oceanic and Atmospheric Administration (NOAA) to conduct studies on the effects of El Nino on the Monterey Bay environment.

One of the UCSC teams is studying how El Nino weather patterns change the reproductive and foraging behavior of northern elephant seals; the group has received $52,000 to fund the research. Another team has received $90,000 to investigate El Nino's impacts on "trophic links" between levels of the food chain in the Monterey Bay Area.

Originating as an abnormal warming of the sea surface in the Pacific Ocean off South America, El Nino causes global climate shifts and usually pushes more than the average number of winter storms into California. This year's El Nino is one of the strongest, if not the strongest, El Nino event ever, according to NOAA, and is expected to continue to have enormous impact on the U.S. over the next several months.

NOAA plans to award $2.1 million to scientists at universities and government agencies this year to fund studies of "unusual environmental conditions or impacts" associated with El Nino.

Assistant research biologist Daniel Crocker and biology professors Daniel Costa and Burney Le Boeuf began work in December on their project, which will shed light on how El Nino weather patterns affect elephant seal behavior.

The researchers are monitoring the breeding period at Ano Nuevo State Beach, tracking the numbers of successfully breeding seals, the weight of pups, the numbers of pup deaths due to storm tides, and the length of the pups' first trips to sea.

Using satellite tracking devices and instruments attached to 10 female elephant seals, the group is also comparing the seals' diving behavior and body mass with data collected in years not affected by El Nino. The instruments on the seals will also provide researchers with readings of water temperature at various depths throughout the Pacific Ocean.

In the second research project, team members will compare data collected during the present El Nino with surveys of seabirds, marine mammals, and krill populations collected during the past two years to examine El Nino's impact on the Monterey Bay food chain. The team is led by research biologists Donald Croll and Baldo Marinovic of UCSC's Institute of Marine Sciences.

In non­El Nino years, nutrient-rich waters upwelling between Ano Nuevo and Davenport flow south into the bay and support the growth of one-celled plant organisms known as phytoplankton. The phytoplankton are eaten by krill, tiny marine crustaceans that in turn become food for seabirds, rockfish, squid, and whales and other marine mammals in the Monterey Bay.

During prior El Nino years, scientists saw a reduction in the upwelled water and a corresponding decline in the phytoplankton population, said Croll. Croll's group expects this year's El Nino to have a similar effect. The group is tracking the numbers of seabirds and marine mammals and measuring the density of krill to gauge what effect the reduced phytoplankton levels have on the rest of the food chain. Croll and Marinovic are also monitoring water salinity, temperature, and depth at stations set up around the bay.

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