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2009 Alaska Marine Science Symposium

Student Winners

• Markus Janout, winner of the best oral presentation (Ph.D. student category)

Title: Temperature controlling processes and the recent cooling in the northern Gulf of Alaska

A slide from Markus Janout's winning presentation on the cooling of the northern Gulf of Alaska. Click on the image to download a PDF version of the presentation (851 KB).

Co-authors: Russell Hopcroft, Kenneth Coyle, Tom Weingartner

Advisor: Tom Weingartner

Abstract:

In spring 2007, oceanic temperatures throughout the water column in the northern Gulf of Alaska (GOA) were the lowest since the early 1970s, and remained below normal through 2008. Stratification was weak due to higher surface and lower near-bottom salinity, likely associated with delayed spring snowmelt. In particular, the 0-100m temperatures along the Seward Line remained below normal, whereas >100m temperatures were more variable, due to salt stratification. Atmospheric and oceanographic data confirm that salinity (as a function of coastal freshwater runoff) is a controlling parameter for deep mixing and the vertical extent of winter-cooled surface waters. Salinity structure is therefore critical for the physical environment of the GOA ecosystem. Evidently, the recent cooling caused delays in the onset and development of (at least) primary and secondary producers.

We present oceanographic observations from the 2007 and 2008 cooling years in comparison with long term trends at the coastal GOA station GAK1 and further investigate the temperature controlling processes along the Seward Line. In particular, we focus on the contribution of alongshore advection to the northern GOA heat and freshwater budget and on cross-shelf gradients in atmospheric heat fluxes.

• Mayumi Arimitsu, winner of the best poster (M.S. student category)

Mayumi Arimitsu's winning poster on Kittlitz's murrelets. Click on the image to view a high-resolution version.

Title: The influence of glacial features on oceanographic gradients in Kenai Fjords, Alaska: A closer look at Kittlitz's murrelet foraging habitat

Advisor: Nicola Hillgruber

Co-authors: John Piatt, Nicola Hillgruber, Erica Madison 

Abstract:

Physical oceanographic processes can dramatically influence community structure in marine and estuarine systems, but these processes are poorly understood in glacially influenced waters. As part of a larger study to define critical marine habitat for Kittlitz's murrelet (Brachyramphus brevirostris) foraging habitat requirements, we conducted oceanographic surveys in two glacial fjords in the Kenai Fjords National Park over the course of the 2007 and 2008 breeding seasons. While the outer fjords are exposed to oceanic waters of the Gulf of Alaska, the inner fjords are influenced by tidewater glaciers. The inner fjords and outer fjords are demarcated by neoglacial terminal moraine shoals that represent the position of the glacier terminus during the Little Ice Age maximum. In June, July and August, we took conductivity- temperature- depth (CTD) profiles in both fjords at 8-10 stations stratified between inner and outer fjord. Here we will describe differences in oceanographic characteristics relative to glacial features within fjords over the course of each summer. Analyses suggest that Kittlitz s murrelets predominately occur in the inner fjords and prefer the colder, turbid (silt-laden) waters near the head of the fjords, where estuarine conditions are most pronounced.

•Nathan Stewart, winner of the best poster (Ph.D. student category)

Title: Patterns in sea otter resource selection in Kachemak Bay, Alaska

Nathan Stewart's winning poster on sea otters in Kachemak Bay. Click on the image to view a high-resolution version.

Advisor: Brenda Konar

Abstract:

Sea otters (Enhydra lutris) are known to forage extensively in both rocky and soft-bottom habitats throughout their range in Alaska. Their ability to significantly reduce prey abundance, limit prey size, and consequently alter community structure has been well documented. Much of this research, however, has focused on sea otter interactions with rocky habitats and associated epifaunal invertebrate prey. Relatively little is known about how sea otter interact with heterogeneous habitat types within their natural range and how this relates to patterns in their local foraging ecology and distribution.

In Southcentral Alaska, sea otters occupying the shallow, broad shelf habitats of Kachemak Bay have access to both rocky and soft-bottom habitat types. The proximity of different grain sizes in the bay provides a unique opportunity to relate known sea otter foraging activity, gathered via telemetry, to a particular substrate type and associated prey community. The recent VHF tagging of 44 sea otter in Kachemak Bay (FWS 2007) has indicated a broad use of habitats and highly variable patterns in seasonal resource use. Our study, carried out during the summer of 2008 in collaboration with FWS, sampled across contours in sea otter utilization distribution in order to investigate mechanisms driving local resource selection.

Sea otter foraging sites (n=36) were identified using GIS and binned based on magnitude of use. Habitat type was quantified by grain size and live prey and the sea otter cracked-shell record were sampled using SCUBA. Length to mass and mass to energy density were calculated using species-specific conversion factors. Multivariate analysis was used to interpret the contribution of biomass (mg dry mass/m2) and energy per unit area (J/mg dry mass/m2) of available prey species to patterns in the preferential selection of certain grain sizes. Results from this research suggest that otter prefer gravel and cobble habitats, grain sizes most commonly associated with patchy but calorically rich crab species in the bay.

Findings from this study provide a baseline description of the relative productivity and potential contribution of particular habitats to sea otter diet in Kachemak Bay, information critical to the monitoring and management of sea otter.

Other presentations and posters by SFOS attendees (click on title to view abstract as a PDF):

Oral Presentations: SFOS Faculty and Staff

Oral Presentations: SFOS Students

Posters: SFOS Faculty and Staff

Posters: SFOS Students