Study the Science: Benthic Ecology

Benthic ecology in the Chukchi Sea focuses on animals like marine worms, clams, snails, sea stars, sea cucumbers, crabs, and shrimps that live in and on the sea floor. These bottom-dwelling (or “benthic”) communities flourish in the Chukchi Sea, where phytoplankton and other “primary producers” that create food from the sun’s energy are able to reach the sea floor. Benthic systems play an important role in recycling nutrients and storing organic matter. The benthic ecology team samples a variety of benthic animals to understand how their communities are composed and what environmental factors influence their community structures.

Interesting Fact:
The beautiful basket star is actually a predator that feeds by extending its many-branched arms into the water to catch particles and zooplankton with its microscopic hooks. It can even capture small fish!

Investigators

Study Descriptions by Year

Reports


2008-2014

Arny Blanchard, Ph.D.

UAF

Co-Principal Investigator

127 O'Neill PO Box 757220

Fairbanks, AK 99775

907-474-1123

alblanchard@alaska.edu

website

2008-2014

Ann Knowlton, Ph.D.

UAF

Project Manager/Outreach Coordinator

127 O'Neill PO Box 757220

Fairbanks, AK 99775

907-474-5966

alknowlton@alaska.edu

website

2014: The 2014 benthic ecology component of the CSESP investigated the community ecology of invertebrate organisms living within and on top of the sediments in across part of the Greater Hanna Shoal Study Area and into the nearshore region. We continued investigations of the spatial distributions of macrofauna by investigating a new spatial breadth encompassing the nearshore and offshore areas.

2013: The 2013 benthic ecology component of the CSESP investigated the community ecology of invertebrate organisms living within and on top of the sediments in the Burger, Klondike, and Statoil study areas in the northeastern Chukchi Sea. We continued investigations of macrofauna in the area focusing on temporal change over seven years.

2012: The 2012 benthic ecology component of the CSESP investigated the community ecology of invertebrate organisms living within and on top of the sediments in the Greater Hanna Shoal Study Area. We continued investigations of meiofauna, macrofauna, megafauna, and food webs in the area. We also initiated a study of the energy content of benthic communities across the study area.

2011: The study area of the 2011 CSESP was expanded to encompass an area from Klondike in the south to Hanna Shoal in the north, called the Greater Hanna Shoal Study Area. The benthic ecology team sampled macrofauna, investigated megafauna using digital photography, began a pilot study for meiofauna (very small animals living with sediments), measured caloric content of key walrus prey items, and investigated food webs. Bivalves (walrus prey) were dominant southeast of the Hanna Shoal area and northeast of the Burger study area. Food webs varied noticeably with differences in the type of food reaching the seafloor in each study area during late summer. There were significant variations in the isotopic signature of the dominant polychaete Maldane sarsi among the Klondike, Burger, and Statoil study areas. Indirect effects of variations in water circulation due to topographic changes (high and low spots on the seafloor) are strong, controlling factors of benthic communities in the study area.

2010: The benthic ecology component of the 2010 CSESP investigated the ecology of benthic communities in the Burger, Klondike, and Statoil (new in 2010) study areas in the northeastern Chukchi Sea. The benthic ecology team also sampled three stations where gray whales were observed feeding and added five stations between Burger and Klondike. The team continued investigation of macrofauna and megafauna community structure and the food web study. We found substantial spatial and temporal variations in biomass and density between the study areas with Burger having greater biomass and density than Klondike. Statoil had similar environmental and biological community characteristics to both Klondike and Burger. Additionally, biomass and density values in Burger and Klondike were higher in 2009 than either 2008 or 2010. The temporal variations in benthic communities coincided with interannual differences in oceanographic conditions. Preliminary results suggested significant differences in food webs between the study areas.

2009: The benthic ecology component of the 2009 CSESP investigated the ecology of benthic organisms in the Burger and Klondike study areas in the northeastern Chukchi Sea. In our second year of sampling we continued the investigation of macrofaunal and megafaunal community structure and added six coastal stations where gray whales were observed feeding in 2009. We found large differences in the biomass and density between the study areas for both macro- and megafauna with Burger, again, having greater biomass and density than Klondike. The offshore study areas were dominated by polychaetes and bivalves and the coastal mammal-feeding stations were dominated by amphipods, the favored food of gray whales. An investigation of differences in food webs between the study areas was initiated in 2009.

2008: The benthic ecology component of the 2008 CSESP investigated the ecology of macrofauna in the Burger and Klondike study areas. In our first year, we focused on spatial variations of benthic communities and community structure, and the environmental variables associated with community variations. The soft sediments of the study areas were dominated by the marine worm (polychaete) Maldane sarsi and the bivalve Ennucula tenuis. Polychaetes and bivalves were dominant across both areas. We found large differences in the biomass and density between the study areas with Burger (to the west of a biological hotspot) having greater biomass and density than Klondike, in spite of small differences in environmental gradients in water depth, sediment grain-size, and bottom-water temperature.