Farallon Institute Newsletter - Fall 2019

Around The Office

Farallon Institute’s Dr. Bill Sydeman has been invited to join the North Pacific Research Board (NPRB) Science Panel.  As part of the Science Panel, Bill will be part of the review process for research proposals and the allocation of funding to researchers, and will help set the direction of NPRB’s general research program.  The NPRB supports high-quality research to better understand the North Pacific, Bering Sea, and Arctic Ocean ecosystems and fisheries.

In October, Farallon Institute scientists Bill Sydeman, Jeff Dorman, Marisol Garcia-Reyes, Sarah Ann Thompson, and recent alum Brian Hoover (now of Chapman University) attended the PICES Annual Meeting in Victoria, Canada.  The topic of the annual conference is marine science of the North Pacific and consists of workshops and sessions of contributed presentations by scientists from six countries.  The members of our group gave seven oral presentations, one poster presentation, and convened one workshop.

State of the Ocean - Fall 2019

You may have read the news from NOAA that a new marine heat wave (now known as “NEP19”) began brewing off the West Coast this past September.  Since then, we have kept our eyes on the North Pacific for signs of the NEP19 becoming the new ‘Blob’ and reaching the West Coast.  As of this late October, the NEP19 has a signature different from the 2014–2016 Blob.  This is good news for our side of the Pacific Ocean, in the sense that the area of warm sea surface temperature anomalies has moved further offshore (Figure; see also NOAA’s marine heat wave tracker) and left temperatures in the California Current relatively normal.  However, in the southwestern side of the Gulf of Alaska—where there have been a couple sequential years of anomalously warm waters—the NEP19 continues to be strong and it is forecasted to be as intense as the ‘Blob’ over the coming winter (Di Lorenzo, PICES meeting 2019).   

Alcatraz Island 2019 field season concluded

Farallon Institute scientist Zoe Burr conducts our breeding seabird monitoring on Alcatraz Island twice-weekly from March to September each year.  On the island, she counts the population size of Brandt’s cormorants and monitors how successfully they reproduce.  This year, and since 2017, the cormorant population has reached record numbers.  This could be a response to the recovery of populations of their favored prey species, small fish such as anchovy, also increasing since 2016.  Due to ocean climate processes, these prey species declined in abundance from 2008–2015, and the cormorant breeding population and reproductive success on Alcatraz also suffered.  In 2009, the cormorants did not successfully breed at all.  Since there is now more food for the cormorants, their populations appear to be healthier.   

Despite the high number of breeding cormorants on the island this year, they raised substantially fewer chicks compared to previous years due to a couple of harsh weather events.  Some Bay Area locals may remember the storm in late May that brought significant rainfall.  Following that storm, we observed that approximately 60% of studied nests lost eggs or chicks.  Then, only weeks later, a heat wave led to additional mortality of cormorant eggs and chicks.  This demonstrates how extreme weather events, which are expected to become more frequent with climate change, can have direct harmful effects.  Our Alcatraz monitoring program seeks to establish connections between seabird population characteristics and human and natural disturbance, and this information can be used for better management both of the seabird colony at Alcatraz and California fisheries. 

Marine top predators as climate and ecosystem sentinels

Newly published research describes ecosystem sentinel species as those that respond to variability and change in the ecosystem in a timely, measurable, and interpretable way.  These species provide an observable link between physical processes and biological responses and can indicate otherwise unobserved change in ecosystem structure or function.  In other words, by watching a particular species, we can learn about change in the environment that we may not have otherwise been able to see at that time.   

Additionally, sentinel species can be used predictively when they are exposed to changes earlier than other species or when their sensitivity to environmental changes means they respond to those changes earlier than other species.  The canary in the coal mine is a commonly-known example of a sentinel species—the birds were affected by dangerous gases in coal mines that couldn’t be seen or smelled, and they became sick before the gases reached levels that were dangerous for the coal miners.  As with the canaries, effective sentinel species should respond to the environmental change quickly and in a detectable way, and species that respond faster make for better sentinels.   

Things we can measure about sentinels are their diet, movements (where are they seen and when?), size and health, reproductive success, and population size.  Changes in these characteristics might indicate changes in the environment.  Marine top predators such as seabirds and marine mammals are suggested to be ideal sentinel species since they are easily observable (compared to other ocean animals) and highly sensitive to environmental changes.  Seabirds, whales, sea lions, and polar bears have already been shown to be valuable sentinels of environmental change, and if we continue to pay close attention to them, we can monitor and predict otherwise unobservable changes in our complex and dynamic oceans. 

See the entire paper by Hazen et al. in Frontiers in Ecology and the Environment.

Using seabird nests to examine their seasonal diet

Each day, some seabirds regurgitate pellets of undigested hard parts of their food, such as fish bones and squid beaks, and analysis of these pellets can provide researchers with information about their diet.  Collection of pellets greatly disturbs the birds and therefore, pellets are typically only collected following the breeding season when birds have vacated the colony.  However, this provides diet data from only the end of the breeding season.  Farallon Institute scientists have developed a new method, collecting and processing the entire nest at the end of the breeding season, to get a more complete view of what the birds were eating over the entire breeding season.      

A study by Farallon Institute researchers on Alcatraz Island analyzed Brandt’s cormorant diet from regurgitated prey parts found in nests and compared this to diet information from pellets.  When the cormorants left the colony in the fall, the nesting material was collected and sorted for pellets and other prey hard parts.  The study compared the diets found in a) the pellets outside the nests (diet in ~24 hours) with b) the nest material (diet over the entire breeding season), and is outlined in a recent article by Heather Robinson et al. in the journal Waterbirds. 

Results of the study showed that the nests contained a greater diversity of cormorant prey and different amounts of individual prey species than the pellets.  Since the nest represents a whole season of dietary information while the pellets are formed from food consumed in just one day, this could indicate variability or changes in foraging behavior over the course of the season.  The nests also contained more evidence of the species that are consumed by cormorants less often, meaning that nest collection provides more comprehensive diet information.  With these results, Farallon Institute researchers have outlined another valuable method for studying seabird diet.