Current Research, Students, & Collaborations

Current Research, Students, & Collaborations

Ongoing Research
[Graduate students and collaborators are listed in brackets]

Effects of prey dispersion and sea ice variability on the joint suitability of protected areas for eiders and subsistence hunters

Four species of threatened or declining eider ducks that nest in the Arctic migrate through the northeast Chukchi Sea, where anticipated industrial development requires prioritizing areas for conservation. In this nearshore corridor (10–40 m depth), the eiders’ access to benthic prey during the spring is restricted to variable areas of open water within sea ice.

Sampling in 2010–2012 showed that large areas of profitable prey densities occurred only in certain locations within the migration corridor. Satellite data in April–May over 13 years (2001–2013) indicated that access to major feeding areas through sea ice in different segments of the corridor can vary from 0% to 100% between months and years. In a warming and increasingly variable climate, unpredictability of access may be enhanced by greater effects of shifting winds on unconsolidated ice. Our results indicate the importance of having a range of potential feeding areas throughout the migration corridor to ensure prey availability in all years.

In addition to concerns for the animals themselves, sea ducks (along with seals and walruses) are important subsistence species for Native people of the Chukchi Sea coast. Access to these animals by hunters is greatly affected by annual and seasonal variations in nearshore ice conditions, and in recent years the extent, thickness, and stability of landfast ice have decreased. To identify areas of conservation concern, habitats critical to animal populations, as well as access to those animals by subsistence hunters, should be considered together in spatial planning. In this project, we are using analyses of benthic samples and remote sensing of long-term ice conditions, as well as a series of workshops in the Inupiat village of Wainwright, to prioritize the value of particular areas for both eider feeding and eider hunting. [Jim Lovvorn, Aariel Rocha, Stephen Jewett, Katie Christie, Tuula Hollmen, Henry Huntington]

Aariel Rocha elders-in-seaiceEiders in sea ice
Subsistence hunting of eiders Future hunters

Measuring and modeling climate effects on organic matter sources and benthic food webs of the northern Bering Sea

Effects of climate change are most evident in the Arctic, where the extent and timing of sea ice cover has changed dramatically. Decreased sea ice is expected to reduce organic matter inputs to the benthos due to changes in the character and timing of spring blooms, with important effects on benthic communities and their predators (sea ducks, bearded seals, walruses, gray whales). Based on gut contents, stable isotopes, and fatty acid biomarkers, we have shown that deposit-feeding invertebrates in this region consume mainly bacteria that in turn feed mainly on the longer-term pool of sediment organic matter. Our computer simulations of the effects of decreased organic inputs to benthic communities, verified by comparisons with field samples, project less stable assemblages with loss of some upper-level predators. Our research is now focused on quantifying mechanisms to develop better predictions of community changes, and on linking highly mobile top predators with processes affecting the patch structure of their benthic prey. [Jim Lovvorn, Chris North (student), Jackie Grebmeier, Lee Cooper]

Chris North with tub

Chris North

Food Web Linkages

Food web linkages from microalgae to predators

Marine versus inland sources of contaminants and egg nutrients in sea ducks nesting on Alaskan Arctic tundra

Long-tailed Ducks and King, Spectacled, and Steller’s Eiders spend most of the year at sea, but return to tundra wetlands to nest and raise their broods. For egg-laying and incubation, the large-bodied King and Spectacled Eiders are believed to depend mostly on nutrients stored during their time at sea, whereas the small-bodied Steller’s Eider and Long-tailed Duck are expected to depend more on foods in local wetlands. Both offshore and onshore habitats are increasingly threatened by industrial development throughout the Arctic. Thus, it is increasingly important to know what habitats are being used to acquire nutrients for egg production and incubation, and where the birds are exposed to contaminants that sea ducks are accumulating at high levels. Based on stable isotopes in egg membranes vs. marine and inland prey, this study will indicate the environments used for pre-breeding conditioning by sea duck species with differing body size, wintering location, migration distance, and contaminant loads. [Micah Miller (student), Jim Lovvorn]

Micah Miller

Micah Miller

Incubating eider

Incubating Spectacled Elder

Nest success and effects of provisioning rates on chick growth in Kittlitz’s Murrelets nesting in alpine scree of Kodiak Island, Alaska

Kittlitz’s Murrelets are seabirds that nest on scree slopes above tree line and return to the ocean to feed and gather food for their chicks.  For unknown reasons, numbers of this species are believed to have declined substantially over the last few decades.

This study will complete a 7-year time series of data on nest site selection, foods fed to chicks, chick growth rates, and nest and fledging success.  In particular, it appears that annual variations in sea surface temperature and associated phytoplankton production result in important variations in the lipid content of the murrelets’ main fish prey. We are testing the idea that annual variations in prey lipid content, by affecting chick growth rates, in turn result in varying lengths of time the chicks are exposed to high rates of predation at the nest. Thus, although predation by terrestrial predators is the main cause of mortality for chicks, this terrestrial predation may be mediated by climatically varying oceanic conditions. [Tim Knudson (student), Jim Lovvorn]

Tim Knudson

Tim Knudson

Kittlitz's chick

Kittlitz’s Murrelet chick

Physiology and climate in keystone prey: effects of changing food and temperature on the energetics of infaunal bivalves

Models to project the effects of climate change on aquatic invertebrates typically depend on estimates of metabolic responses to increasing temperature. However, many studies suggest that invertebrates show greater metabolic response to availability of food than to temperature per se. Moreover, most respirometry studies of deposit-feeding invertebrates have removed the animals from the sediments in which they live and placed them in empty experimental chambers – this protocol likely results in unreliable metabolic responses. Unfortunately, measurements of oxygen consumption of animals embedded in their sediments are confounded by respiration of sediment bacteria. This study will use enzymes of the electron transport system to assay the oxygen consumption of bivalves buried in sediments of varying organic content at different temperatures. This method will yield more realistic measurements for these critical prey of many top predators, and better account for factors affecting their response to climate change. [Tony Roberts (student), Jim Lovvorn, Marjorie Brooks]

Tony with Aquarium, 12 May 16Tony Roberts Infaunal BivalveInfaunal Bivalve

Long-term variations in irrigation deliveries to wetlands in the Laramie Basin, Wyoming, and effects on diversity of wetland communities

In the arid western United States, wetland communities commonly depend on the amount and frequency of water they receive from intensively managed irrigation systems. Because of western water laws, allocation of water to each headgate and property throughout an irrigated watershed is often quite predictable from inputs derived from snowpack in surrounding mountains. Legally prioritized allocations of water have in many cases not changed since human settlement in the late 1800s. In a typical irrigated western valley, the Laramie Basin, Wyoming, our studies have shown that the structure of wetland food webs differs greatly with the frequency of water deliveries, owing to resulting variations in salinity and drying to which different taxa are differentially sensitive. Variations in wetland assemblages include differences in species and structure of vegetation, relative production by plants and algae, and the relative abundance of invertebrate grazers and their invertebrate, fish, and avian predators. Understanding how varying water deliveries maintain the diversity of wetland complexes is critical to sustaining wetland habitats as snowpacks decrease and growing human populations demand more water. This study will be the first to analyze long-term data on irrigation deliveries to wetlands throughout an intermountain basin to evaluate how varying climate affects regional wetland diversity. [Jim Lovvorn, Aariel Rocha]

Irrigated Wetlands

Wetlands associated with irrigation
storage and delivery

Laramie Wetland ComplexComplex of wetlands in the Laramie Basin