Collaborative research in southwest Alaska: Mussels, mollusks and more, part 2

Seattle Aquarium Animal Care Specialist Caroline Hempstead traveled to the coastline of Alaska’s Katmai National Park and Preserve from June 28 to July 10, 2019. Caroline assisted with a variety of research being conducted as part of a long-term monitoring program of the area. These efforts were part of the National Park Service’s Southwest Alaska Inventory and Monitoring Network as well as part of Gulf Watch Alaska, the long-term ecosystem monitoring program of the Exxon Valdez Oil Spill Trustee Council for the marine ecosystem affected by the 1989 oil spill. Check out Caroline’s account of her experiences in Alaska below!

 

Map of Katmai National Park
Map of Katmai National Park

 

PART 2: CRUISING FOR SEA OTTERS, INVERTEBRATES AND SEAWEED

DAYS 4–6
Cruising by a resting sea otter.
Cruising by a resting sea otter.

Day 4

At 4am, Jim, Heather and Brian R. headed out to survey more transects along the Katmai coast. The Miss Diane left shortly afterward and motored down the coast to Devils Cove in Kukak Bay. Once anchored in Devils Cove, Dan and I took one of the skiffs and checked around the small islands that dot the cove to see if we could find any sea otters feeding in the area. We found a few individuals and started collecting foraging data. Otters were eating various clam and crab species, as well as mussels.

Sea otters were hunted to near extinction along the Katmai coast during the Pacific maritime fur harvest, and only since the end of this harvest (1910) have populations been allowed to recover. Along the Katmai coast, recovery has been quite recent with relatively stable population numbers in the last decade or so (around 6,600). While oil from the Exxon Valdez spill did impact the Katmai coast, we know sea otter numbers were already low in 1989 (when the spill occurred). Given that, direct sea otter mortality from the oil spill was likely low. We believe the Katmai sea otter population has reached carrying capacity (the maximum population of a species that an area will support without the area deteriorating) based on our surveys, analysis from forage data collection and a variety of other data streams.

During the evening hours, Jim, Dan and I headed out to catch some black rockfish and kelp greenling using rod and reel. The otoliths (ear bones) are harvested from the fish to measure growth rates, an indication of primary ocean productivity in the prior year. Additional muscle tissue was harvested from the fish to analyze stable isotopes, which are an indication of what the fish have been eating.

 

Day 5

While anchored in Devils Cove, the scientists divided into three teams, jumped into their skiffs and cruised over to Kukak Bay to sample the intertidal invertebrate and seaweed communities. We sampled 15 intertidal sites over the next five days along the Katmai coast. The objective of this work is to monitor long-term trends in the species composition, size and abundance of invertebrates and seaweed species in the area. These seaweeds and invertebrates form the base of the food chain as primary producers and primary consumers.

We sampled all sites during a minus low tide to allow enough time to complete all the tasks and sample as much of the intertidal area as we could without going underwater. The sites included sheltered rocky habitats and mixed sand-gravel (soft sediment) habitats, as well as mussel bed sites. The intertidal marine invertebrate and seaweed communities play an important role in sustaining a healthy and balanced nearshore ecosystem. They also provide important sources of nutrients and energy to both marine and terrestrial carnivores such as sea otters and brown bears that forage in the marine habitat.

 

Brenda and Jim setting up for a mussel transect in Kukak Bay.
Brenda and Jim setting up for a mussel transect in Kukak Bay.

 

Once the mussel transects were completed, we made our way back to our home base, the Miss Diane, where the invertebrates we collected were processed. The mussels were measured and entered into the database and frozen for further analyses back in the lab. The same process was done for the invertebrates collected from the soft sediment site, which, in addition to mussels, included several clam species.

 

Brian U., Heather and Brenda getting set up to measure mussel and clam species from the soft sediment and mussel sites.
Brian U., Heather and Brenda getting set up to measure mussel and clam species from the soft sediment and mussel sites.

 

We decided to take advantage of the calm waters in Devils Cove to collect some more sea otter foraging data back on the rooftop of the Miss Diane. We observed a few more foraging dives on several otters. It was a good, productive day, but it was time to move south to our next site in Kaflia Bay.

 

Scope set up on the roof of the Miss Diane.
Scope set up on the roof of the Miss Diane.

 

Day 6

Anchored in Kaflia Bay, the teams headed out in the morning on their skiffs to their intertidal sites. I joined Heather, Kelsey and Elsie on the soft sediment sampling site deep inside Kaflia Bay. The site was picturesque!

 

Ash-covered mountains in Kaflia Bay from the 1912 volcano eruption of Novarupta.
Ash-covered mountains in Kaflia Bay from the 1912 volcano eruption of Novarupta.

 

As the tide changed, the narrow channel between the land formations became a river as the water rushed out (ebb tide) from the bay as we made our way to our soft sediment site. Heather, not only our leader for the trip but a veteran boat operator, easily and flawlessly steered through the shallow, narrow channel. As we motored along, I noticed the rocks were covered with thousands and thousands of mussels, giving the appearance of a black velvet cloth.

 

Thick mussel beds through a narrow channel in Kaflia Bay.
Thick mussel beds through a narrow channel in Kaflia Bay.

 

Sampling the soft sediment site was a tough, backbreaking job that involved shoveling several hundred pounds of sand, rock and cobble into buckets from 10 quadrats along the transect and then sifting each bucketload through a sieve to collect the clams and mussels. It was a good reminder to lift with our legs and not our backs! Next we headed back to the Miss Diane for some lunch. Brenda, Dan and I stayed on board to measure the many thousands of mussels and clams and enter data from the soft sediment and mussel sites.

 

Jim, Brenda and Heather at mussel bed site in Kaflia Bay.
Jim, Brenda and Heather at mussel bed site in Kaflia Bay.
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