Farallon Institute Newsletter - Fall 2020

Around The [Home] Office

Microplastics in the ocean are a big problem for the organisms that live there and inadvertently consume them, and there is concern as well that humans are consuming microplastics through the seafood that we eat.  Farallon Institute’s Julie Thayer is helping tackle this problem by serving on the California Ocean Science Trust’s Microplastics Working Group that was formed in early 2020.  The working group will provide scientific guidance to the state on the sources and potential effects of microplastics on the marine environment and human health.

Since Julie is an ecologist, she provides expertise on different kinds of organisms and marine habitats that might be particularly susceptible to microplastics pollution.  Subsequently, the group can focus on important fisheries that lead to human microplastic consumption (halibut, oysters, etc).  While there are still big knowledge gaps about microplastics, working groups such as this one guide management in a precautionary manner and recommend new research to fill those gaps.  

We’d like to remind everyone to support Farallon Institute through Amazon Smile this holiday season.  Amazon donates to an organization designated by you when you shop through smile.amazon.com, at no extra cost to you.  Thank you!

State of the Ocean

State of the Coastal vs. Open Ocean 

In the last few summers, California’s ocean has experienced two divergent trends in temperature.  In coastal areas of central and northern California, conditions were normal for the most part: cool waters brought to the surface by upwelling-favorable winds (as shown by our ocean indicator MOCI).  In contrast, offshore regions of the ocean have experienced more frequent periods of anomalous warm water, classified as marine heatwaves (MHW).  The latest MHW, which started in August and is ongoing (see figure and the NOAA MHW Tracker), is the second largest after the 2014–2016 MHW, a.k.a. ‘The Blob’.  Both of these MHWs developed under neutral El Niño conditions rather than warm ocean climate events, however, and their increased frequency has been attributed to climate change(1).

Under normal conditions, coastal zones of the California Current are cool, providing a suitable habitat for California’s diverse marine ecosystem.  High ocean temperatures shrink this rich area(2), which pushes marine life against the shore and increases conflict between fisheries and wildlife.  One consequence is more whales foraging closer to shore than normal, leading to increased incidents of whale entanglement in crab fishing gear.  To protect the whales, the state has delayed the commercial Dungeness crab fishing season for the second year.

(1) Laufkotter et al. 2020, Science
(2) Santora et al. 2020, Nature Communications

Marine mammals and California wildfires

The terrible wildfires that raged in California in August of this year and displaced many people also forced the evacuations of marine mammals housed in laboratories of University of California Santa Cruz’s Long Marine Laboratory.  Just as for people, the smoky air was hazardous for the dolphins, sea lion, and seals that reside there.  Additionally, there was concern that the lab itself would be included in an evacuation order, and moving these types of animals to other facilities is no easy feat.  Lab staff decided to put this in motion before it was required.   

Most of the lab’s pinnipeds – a California sea lion, a harbor seal, a ringed seal, and two bearded seals – were transported to the Marine Mammal Center in Sausalito, CA.  Additionally, a Hawaiian monk seal and two dolphins made a longer trek to Sea World in San Diego.  The dolphins rode in custom transportation tanks carried in a refrigerated truck to keep them comfortable for the drive.  As with any road trip, this one also included a stop for snacks for everyone.   

By the time an evacuation was ordered that included the area where Long Marine Lab is located, all of these animals were safely out of the area.  Directors noted that the team effort required of people who care for marine mammals in California to take care of an emergency situation such as this one was remarkable and they are proud of how successful the evacuation was. 

This story was originally published by the UC Santa Cruz Newscenter.

Sea otters in estuaries

While sea otters are often pictured happily foraging and floating among the fronds of kelp forests, they were also plenty abundant in estuary habitats prior to their population decimation due to the fur trade.  Currently, about 3,000 southern sea otters live along the central California coast but do not extend past San Francisco Bay.  In this range, resident groups of sea otters live in Morro Bay as well as Elkhorn Slough, in Monterey Bay.  Estuary habitat has a lot to offer the otters—it is safe from predators such as white sharks, it’s easy for the otters to haul out for resting, and there is abundant food such as clams and crabs. 

Otters are known for their important role in kelp forest ecology as keystone predators: the sea otters eat sea urchins, which themselves eat kelp.  With reduced urchin abundance due to the presence of otters, the kelp is able to grow abundant and provide a habitat for multitudes of other species.  In an estuarine environment, otters can also positively support the habitat, particularly for seagrass.  In this case, otters consume crabs that eat small snails, which clean eelgrass blades of epiphytes and detritus (just like the small snails in fish tanks).  More otters in the estuary means there can be more of the small snails that promote eelgrass health, and the eelgrass beds provide a rich habitat for many other species. 

A new study explored the idea of sea otters expanding into two more estuaries: San Francisco Bay and Drakes Estero, on Point Reyes.  The researchers found that prey is abundant enough in both of these sites to sustain an otter population.  They also applied a population growth computer model to estimate how many otters these estuaries could support.  Model results indicated that San Francisco Bay, colonized with just 20 otters, could support over 5,000 otters within 50 years.  Though there are areas within San Francisco Bay that have the right habitat characteristics for sea otters, it is highly impacted by human use and environmental stresses will persist.  Eelgrass habitats are susceptible to the same stresses, and through their key ecological role, the presence of otters could benefit the local environment.  Careful consideration of environmental and socio-economic benefits and tradeoffs will need to be taken by managers regarding potential reintroduction of sea otters into areas like San Francisco Bay. 

See the full study by Hughes et al. (2020) at PeerJ.