Roundup: Harbor Seals, River Communities and Iceberg Melt

Glacial Habitats of Alaskan Harbor Seals

From Marine Mammal Science: “Harbor seals, Phoca vitulina, use diverse haul-out substrates including ice calved by tidewater glaciers. Numbers of seals at glacial and terrestrial haul-outs on the southeastern Kenai Peninsula, Alaska, were assessed using aerial, vessel, and video surveys. Mean annual abundance at glacial and terrestrial haul-outs differed temporally. From 2004 to 2011, numbers of seals counted during the molt increased 5.4%/yr at glacial haul-outs and 9%/yr at terrestrial haul-outs while numbers of pups increased 5.0%/yr at glacial sites and 1.5%/yr at terrestrial sites.”

Learn more about how harbor seals use glacial habitats here.

Lounging harbor seals (Source: Gregory “Slobirdr” Smith/Flickr).

 

River Invertebrate Biodiversity

From Nature Ecology & Evolution: “Global change threatens invertebrate biodiversity and its central role in numerous ecosystem functions and services. Functional trait analyses have been advocated to uncover global mechanisms behind biodiversity responses to environmental change, but the application of this approach for invertebrates is underdeveloped relative to other organism groups. From an evaluation of 363 records comprising >1.23 million invertebrates collected from rivers across nine biogeographic regions on three continents, consistent responses of community trait composition and diversity to replicated gradients of reduced glacier cover are demonstrated.”

Read more about the response of river invertebrates to decreasing glacier cover here.

River invertebrates, like this one here, were shown to respond reasonably predictably to decreasing glacier cover globally (Source: University of Leeds/Twitter).

 

Greenland’s Freshwater Budget

From Nature Geoscience: “Liquid freshwater fluxes from the Greenland ice sheet affect ocean water properties and circulation on local, regional and basin-wide scales, with associated biosphere effects. The exact impact, however, depends on the volume, timing, and location of freshwater releases, which are poorly known. In particular, the transformation of icebergs, which make up roughly 30–50% of the loss of the ice-sheet mass to liquid freshwater, is not well understood. Here we estimate the spatial and temporal distribution of the freshwater flux for the Helheim–Sermilik glacier–fjord system in southeast Greenland using an iceberg-melt model that resolves the subsurface iceberg melt. By estimating seasonal variations in all the freshwater sources, we confirm quantitatively that iceberg melt is the largest annual freshwater source in this system type.”

Discover more about the freshwater flux of iceberg melt from Greenland’s ice sheet here.

Satellite image of summer (left) and winter (right) fjord conditions for Helheim (H), Midgaard (M) and Fenris (F) glaciers (Source: Moon et al.).
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