I’ll be giving an overview of a large USGS study being led by Jim Bodkin of the Alaska Science Center, but with co-PIs and collaborators from several other USGS centers and many other federal, state, native, university, and private institutions. This study is indebted to Leslie Holland-Bartels of the USGS office of Alaska Area Regional Executive for scientific inspiration and financial support.
With answers to this simple-sounding, yet incredibly complex question, the study design allows for forecasting system responses to climate change (global and oceanic), although we are not at that stage forecasting is not currently part of the study itself.
The questions we’re attempting to address are in no way new questions– they form the basis of ecological studies on sea otters since humans were interested in otters. The difference is that today we benefit from the development and incremental improvements in new technologies– allowing unprecedented inquiries and novel approaches to seeking answers. I’ll point these new technologies out as I go along.
The study area encompasses a large extent of the current range of the sea otter– ~4000km from the Big Sur California coast, northward to Monterey, CA, the Washington state outer coast, the west coast of Vancouver Island, BC Canada, southeast AK , PWS, and the Katmai AK coast.
Along this range of sea otters….Are a number of geographically distinct populations that have undergone different patterns of recovery following protection or translocation after the end of the fur trade --and current population trajectories range from increase to rapid decline, including two threatened populations within our study. There are even different population trajectories evident within individual populations.
The image of the study area might make it seem as though we’re looking at the entire eastern Pacific ocean– yet we’re primarily focusing on the narrow nearshore band out to approximately 40m depth, that is under the influence of the continents and their watersheds. We’re interested in how oceanic influences might affect the nearshore, but we are studying the nearshore.Here’s a short swim in the nearshore, brought to you by 2 divers during one of our sea otter capture trips. I’ll explain why sea otters are captured as part of this study in a bit, but for now here is the nearshore: note the extensive understory – nutrients & habitat for many spp & diff trophic levels eelgrass beds- nursery grounds for pelagic fish and other spp, food source for migratory birds note the light penetration and clear water (not always this way!) note the 3-d bottom topography- important habitat for many plants, inverts, fishes– see the school of fish– nearshoremacroalgae and canopy forming kelps (such as this nereo bed) are havens for fish, snails, crabs, as well as many other spp
I want to take a few minutes to describe more fully the nearshore/offshore/watershed systems. Many people automatically think of offshore/pelagic systems when they think “ocean”. Yet Nearshore marine ecosystems face unprecedented challenges at global and regional scales, with threats arising from both the adjacent lands and oceans. So it important to understand how different the nearshore system is and why it needs to be studied on its own, not lumped in with ocean studies. From the ocean, challenges include acidification, sea level rise, and warming. These are cascading effects arising from increased atmospheric CO2 emissions since the onset of the industrial age. In some nearshore systems, such as those in our sampling universe, kelps, seagrasses, and macroalgae provide the bulk of the carbon fixation– they are the primary producers capturing the sun’s energy to form the base of the trophic web.
From the continents, challenges include elevated biological and chemical pollutants associated with burgeoning human populations along coastlines. Expected consequences of climate change include modifications to the hydrological processes responsible for transporting pollutants, nutrients, and sediments across watersheds that ultimately deposit into nearshore environments which can have adverse biological effects.
As we sample from AK south to California, there will be a range of influence levels on the nearshore derived from increasing human densities and actions and decreasing glacial inputs. Additionally, differences will exist in watershed inputs with respect to freshwater and sediment influxes (and what may be transported & deposited with the waters & sediment particles) and these will likely be influenced by climate change.
This last photo was chosen for its value as an extreme “worst-case’ scenario as far as human influenced inputs into the marine nearshore. It may not be far from the truth however– we might not see such visible signs of human inputs today, but the soup of chemicals flowing into our nearshore is simply staggering.
The study design incorporates ecosystem productivity, watershed inputs, and diet and nutrition as primary factors potentially regulating population abundance and growth rates.
Ecosystem productivity will be estimated through 1) growth rates of nearshore fishes and 2) satellite imagery (e.g., chlorophyll and temperature) and remotely sensed data (e.g., oceanographic stations).
I’m not really going into results today– this is just to illustrate the types of remotely sensed data that can be brought in to our analyses of oceanic inputs to the nearshore. Here is a time series of cholorphyll data from a north to south set of our study sites.This is one of the new & constantly improving technologies that make this project possible.
Two nearshore resident fishes (black rockfish & kelp greenling) have been chosen to aid in quantifying productivity of the nearshore at our study sites. These fish have small home ranges similar to sea otters and are long-lived. The fishes annual growth rates are a reflection of nearshore productivity. Fish have ear bones called otoliths which have annual growth lines –similar to tree rings– the width of the line is representative of the amount of food available to the fish. The rings can be counted to get the age of the animal, then productivity estimates established for each year. Additionally, stable isotope alalysis can be conducted on material from each band, to determine if the productivity of the system in a given year is nearshore derived, offshore derived, watershed-derived carbon-sources.BLRO = 20 yrs. Diet = pelagic nekton, zooplankton, juv fishKEGR = 12 yrs. Diet = seaworms, crustaceans, small fishHabitats = kelp holdfasts, understory & kelp canopy.
Sea otter diet and nutrition will be estimated through direct observation of foraging.
Direct observations of foraging is exactly what it sounds like. We can quantify what otters eat because they do so at the surface. With this information we can calculate how many hours in a day an otter needs to forage to meet its energetic requirements. Where food is limited, it will take longer. Body condition is also a useful parameter for assessing food resources available to populations.
Watershed modifications and inputs into the nearshore will be estimated through satellite imagery (e.g. Landsat & MODIS) and hydrographic stations.
Similar to the chlorophyll slide, this is provided to give a conceptual idea of how data can be integrated into our analyses– this time from watershed inputs. Here is a listing of the many data layers and processes that will be evaluated for inclusion into the models.
Concurrently, we will evaluate the health as reflected in sea otter health assessments and the expression of genes (as novel biomarkers) specific to: 1) organic pollutants, 2) metals, 3) parasites, 4) bacterial infection, 5) viral infection, and 6) thermal stress, in each sea otter population.
Vet screenings are analgous to what many of us undergo at annual checkups– a routine physical, serum chemistry looking at liver enzymes, and other analytes, as well as testing blood for infectious diseases known to occur in marine mammals. Cuts, abrasions, broken bones or teeth, lumps/masses/tumors– all are noted by the veterinary staff. The vet exams serve 2 purposes– to asses the health and well-being of each individual otter as well as provide validation for gene expression results. There are >20 years of captive & wild-caught otter health related data sets available to generate reference ranges.Gene expression analysis is perhaps one of the most exciting emergent technologies that has helped drive the creation of this project. In a nutshell- genes have been identified that are produced in response to varying stressors. The production of these genes can be measured. This is a minimally invasive technique, that measures actual response– not just body burden, and there are diagnostic capabilities associated with the technology already in use in human cancer medicine.
The combined data sets on: 1) nearshore productivity, 2) watershed inputs, 3) sea otter diet and nutrition, and 4) sea otter gene expression will support a multivariate analysis of empirical factors likely responsible for directing the present status and trend of geographically distinct sea otter population, and by inference, the nearshore ecosystem generally.
This slide is just to show that the analysis and modeling of all this data & information is not inconsequential, nor simple– yet again, thanks to new technology– such as increased computer memory, storage, and speed, as well as helpful interfaces such as SAS and matlab and GIS analysis tools– the modeling and analysis is feasible.
We expect that the data we acquire will support future modeling efforts to forecast nearshore ecosystem responses to anticipated environmental change such as increasing temperature, sea level rise, ocean acidification, contaminants, and disease.
Coastalecosystemresponses to influences from land and sea A USGS DOI on the Landscape project
Alaska Science Center
J.L. Bodkin, C. Zimmerman, D. Douglas C. Kolden, V. vonBiela
Western EcologicalResearch Center
A.K. Miles, L. Bowen, M.T. Tinker, W.M. Perry, R. Lugo, J. Yee
Western FisheriesResearch Center
L. Thorsteinson, D. Reusser, J. Saarinen
Coastalecosystemresponses to influences from land and sea Mike Murray, Monterey Bay Aquarium Seth Newsome, Univ. Of Wyoming Linda Nichol, DFO Canada Shawn Larson, Seattle Aquarium Heather Coletti, National Park Service North Pacific ResearchBoard Exxon Valdez Oil Spill Trustee Council USFWS CaliforniaDept. Fish and Game CaliforniaCoastalConservancy Partners
Pacific Nearshore Project The Question: What factors are contributing to the status and trends of contemporary sea otter populations, and by extension to the nearshore?
Marine Productivity Sea Otter Population Status & Trend Sea Otter Health Diet & Nutrition
WatershedGeoaccounting OUTPUT Discharge: 156 m3 / s Silviculture Agriculture Human density Urbanization Industrialization Coastal development Invasive species Hydrology Sediment/nutrient flux Lead: 0.03 kg Phosphorous: 0.156 kg Nitrogen: 0.468 kg Suspended Sediment: 125 kg
Conceptual Design Watershed Inputs Marine Productivity Sea Otter Population Status & Trend Sea Otter Health Diet & Nutrition
Sex / Repr. stat. / Age Watershed factors Blood, serum, gene expression Data Analyses? Hierarchical model Energy Recovery rate Pollution & Pathogens Nutrients Prey availability Regression (site-month level) Health Factor 2 Health Factor 3 Health factor 1
Marine Productivity: Chlorophyll Ocean productivity (chlorophyll) in the nearshore, March vs May (from Pirhala et al. 2009)
Acknowledgements In addition to the researchers and partners:
invertebrates invertebrates invertebrates Watershed inputs Data Analyses? Ecosystem SEM SST Pollution & Pathogens Ocean temperature color Nutrients Ocean chlorophyll Food web (other) Food web (kelp based) Sea otter health fac. 2 Short-term, multi-site data Sea otter Health fac. 1 Prey availability Sea otter diet & energy recovery Population status (growth, l)