Sea ice influence on benthic community variability in the Alaskan Arctic shelves

SCIENCE

Alexandra Ravelo

Despite being a point of interest and study for decades, the Arctic continues to hold a treasure-trove of mysteries and research opportunities. As climate change intensifies, more and more data is needed to understand an ecosystem in flux. 

Alexandra Ravelo, a marine biology PhD student at UAF, is looking to change that. Ravelo has been studying the Arctic – specifically marine invertebrates that live on the seafloor of Arctic shelves – since 2010. Her project increases scientific knowledge of a region that remains poorly understood and which is undergoing rapid environmental changes. 

Ravelo is interested in how a physical environment impacts the diversity, biomass and abundance of marine invertebrates. She is particularly interested in the brittle star, a type of sea star that thrives in the Arctic. 

Since beginning her research almost five years ago, Ravelo has experienced many memorable moments. A recurring scenario involves her talking with oceanographers about her “little seafloor critters”. She often shows them a map of species distribution and explains how these creatures live and disperse across the Arctic. She never tires of seeing their interest and excitement grow as they realize the pattern of distribution of some species is reflecting the oceanographic features they've studied for years.

However, Ravelo's research is more than just sea stars. The Arctic has many resources important to local subsistence and of large scale economic value. Ravelo hopes her research can inform policy makers and government agencies of the diversity of marine invertebrates; as well as what environmental characteristics are important for such marine communities, including sea ice coverage, seafloor characteristics and food supply. 

While the marine invertebrates she studies do not have direct economic value, many of them are prey to birds, marine mammals and fish. “Many of these organisms are slow growing and long lived, so any negative impact of climate change or human development in the area could affect the whole ecosystem,” she said. 

“My research brings in one more piece to the puzzle so that resource managers, government agencies and the public in general can make informed decisions on Arctic resource development,” she said.

Along the Arctic continental shelves epibenthic organisms can be found in high abundance and biomass. Several members of the benthic community constitute key elements of the Arctic food web; as prey of marine mammals, birds and fish (Bluhm & Gradinger 2008). Specifically diving sea ducks, bearded seals, grey whales and walruses feed on benthic organisms. Among the important epibenthic species encountered on the Alaskan Arctic shelves are brittle stars, amphipods, snow crab, hermit crab and shrimp (Bluhm et al. 2009, Ravelo & Konar In Review, Ravelo et al. submitted). Epibenthic communities in the Arctic are dominated by certain taxa over large spatial scales until key environmental drivers interrupt their distribution (Piepenburg 2005, Ravelo et al. submitted). In the Chukchi Sea, echinoderms occur in dense assemblages (several hundred individuals per meter square) and high biomass, up to 30% higher than the highest values reported for echinoderms in the Barents Sea (Ambrose et al. 2001). On the western Alaskan Beaufort shelf epibenthic invertebrates made up to 94% of the total benthic standing stock (Rand & Logerwell 2010).

Profile

Name: Alexandra Ravelo, Graduate Student

Institution: University of Alaska Fairbanks

Mentor: Brenda Konar, bhkonar@alaska.edu

Award: Research Grant

Funding Period: 2014