Grantee Research Project Results
2000 Progress Report: Integrative Indicators of Ecosystem Condition and Stress across Multiple Trophic Levels in the San Francisco Estuary
EPA Grant Number: R827644Title: Integrative Indicators of Ecosystem Condition and Stress across Multiple Trophic Levels in the San Francisco Estuary
Investigators: Dugdale, Richard C. , Kimmerer, Wim , Arp, Alissa J. , Thompson, Janet K. , Bollens, Stephen Morgan , Wilkerson, Frances P. , Julian, David William
Institution: San Francisco State University , Romberg Tiburon Center , United States Geological Survey , University of Florida
Current Institution: San Francisco State University , U.S. Geological Survey - Sacramento , University of Florida
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1999 through September 30, 2002 (Extended to September 30, 2003)
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
Project Amount: $881,062
RFA: Ecological Indicators (1999) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
The objectives of this research project are as follows:
- Establish the utility of the following potential indicators of ecosystem
condition at three stations along a salinity gradient in the San Francisco
Estuary:
- Nutrient status and productivity performance of phytoplankton including the relative contribution of diatoms to phytoplankton biomass and productivity.
- Reproductive rates of common copepod (zooplankton) species.
- Nutritional condition of larval Pacific herring using morphometric characters, some of which are sensitive to growth (food) (e.g., body weight), and some of which are relatively insensitive to growth (food) (e.g., eye diameter).
- Changes in benthic community structure and growth rate, condition, and glycogen content of key benthic organisms.
- Expression of stress proteins in benthic bivalves, larval herring and copepods.
- Investigate relationships of indicators to variation in other physical (e.g., temperature, salinity, turbidity) and biological (e.g., introduced species, copepod prey for herring) parameters.
- Assess the utility of the ecological indicators for use in other locations.
Progress Summary:
Phytoplankton Indicator Study. Measurements of temperature, salinity, nutrients, and algal biomass as chlorophyll were made monthly on 12 water column cruises that occupied three stations in San Francisco Bay along a salinity gradient. These sites have been sampled previously; U.S. Geological Survey (USGS) Station 6 in Suisun Bay, USGS Station 13 in San Pablo Bay and RTC X-Bay Station D in Central San Francisco Bay. Nutrient (nitrate, silicate and ammonium) concentrations were high and unlikely to be limiting - the nutrient status of the phytoplankton in the three sites is likely to be sufficient for good growth. Nutrients were greater throughout the year in Suisun Bay and decreased in concentration going seaward with lowest values in Central Bay. Light penetration (i.e., water clarity) increased seaward with Suisun Bay being the most light limited for phytoplankton productivity. Suisun Bay tended to have lower levels of chlorophyll (or phytoplankton biomass) than the other sites. Throughout the year, larger phytoplankton cells tended to dominate the chlorophyll biomass in San Pablo and Central Bays. At all sites increased levels of chlorophyll a (phytoplankton blooms) were measured during April 2000. Populations were dominated by the chain-forming diatom Skeletonema costatum. During elevated chlorophyll conditions (i.e., > 5 µg/l) the phytoplankton community was mostly made up of larger cells (i.e., not picoplankton). Cells greater than 5 µm or 10 µm diameter made up 80 percent or more of total chlorophyll biomass. 15N-labeled NO3 and NH4 uptake and 13C labeled carbon fixation (fractionated by phytoplankton cell size) experiments were carried out during all the monthly cruises with samples incubated under natural turbidity and clarified water conditions to assess their productivity performance. A total of 458 samples have been collected and the mass spectrometry is being performed with 134 samples completed.
Zooplankton Indicator Study. To date, we have completed 1 year's worth of monthly cruises in collaboration with the phytoplankton project. Copepod (zooplankton) reproductive rates were measured by collecting with gentle net tows, diluting the catch in surface bay water, and incubating individual females for 24 hours in 125 ml polycarbonate bottles filled with bay water with eggs strained out. Data from all but the last cruise have been worked up and analyzed. We are beginning to add elements of the project, including measuring copepod reproductive rates with excess food, determining egg development times, and to re-evaluate the methods used. On one occasion (actually a mid-month cruise, not one of our regular dates) during an egg production experiment we found poor survival and low egg production, which we tentatively attribute to a bloom of a toxic dinoflagellate. Otherwise, survival has been very high in our experiments, most often 100 percent. Reproductive rate has been quite variable, which we tentatively attribute to food limitation, although relationships with chlorophyll are not strong. Experiments conducted over the next year will help to refine that conclusion. The samples taken to determine egg ratios of copepods that carry eggs have been difficult to interpret because most of the eggs have been separated from the females and for some species the eggs cannot be identified to species. We will be trying some alternative sampling methods to try to solve this problem.
Larval Herring Indicator Study. Once a month, between November 1999 and May 2000, we collected triplicate net tows at two stations (San Pablo Bay and Central Bay). We sorted, identified, and measured the anal body depth (mm), pectoral body depth (mm), eye diameter (mm), standard length (mm), head width (mm) and dry weight (mg) of 562 herring larvae. Nine indices of condition were derived for each larva. All nine mean index values were significantly different between months and three were significantly different between locations. These morphometric indices appear to be useful for evaluating nutritional condition in herring larvae and may prove useful as indicators of ecosystem condition or health.
Benthic Indicators Study. We have completed the preliminary analysis of the benthic community data at the Grizzly Bay station (a shallow region adjacent to Suisun Bay) and have found that the community showed a dramatic change with the introduction of the non-indigenous clam Potamocorbula amurensis. We believe one of the stresses to this estuary and others is the large number of species that have been introduced in the last 40 years. This analysis shows that the benthic community had a significant response to the introduction of P. amurensis in 1986. There has been a noticeable decline in the diversity of the benthic community since the introduction of P. amurensis. The benthic community structure before and after the arrival of P. amurensis responds to freshwater flow, with dry-year communities being more diverse than wet-year communities. We will now begin examining these data more closely to determine what other environmental factors may be responsible for these changes in the benthic community. The length of this data set (beginning in 1977) has been the major factor that has made these analyses so clear. Based on the promising results at the Grizzly Bay site, we hope to increase the time series of the benthic data at San Pablo Bay site through analysis of previously unanalyzed samples (see below). Our preliminary analysis of this much shorter data set (beginning in 1994) showed that the benthic community structure and diversity have also changed with changing salinity at this location. Condition, glycogen and growth data are all showing some promise although a longer data set is necessary to make any conclusive comments about their utility as stress indicators. There is an apparent gradient in condition showing that animals are more stressed in the deeper portions of the bay, possibly due to food limitation, during some periods of the year. Very low glycogen values show that P. amurensis has few energy stores. Thus glycogen and condition values for P. amurensis in combination with community structure, which changes dramatically with density changes in this species, may be good indicators of environmental stress.
Our goal had been to occupy a marine station in central bay that was previously monitored by the Regional Effects Monitoring Program. We found, based on 2 days of benthic surveys, that this station is not representative of the central bay benthic community. It appears that this station is located in an area of large current velocities and is thus subject to bottom scour and migrating sand waves. We therefore have established a new station that we believe is more representative of a true marine community. This has caused some difficulty as the taxonomic description of this site has not been previously done. We are now looking for help with many taxonomic problems, including help identifying at least one species not previously described. Although we have been able to maintain the condition and glycogen analyses at this station we expect that we may have to alter our sampling/analysis regime to accommodate the large increase in time required to describe this community; we will initially attempt to examine one replicate sample per month.
Stress Protein Study. The work on stress-induced proteins was delayed this year as one Principal Investigator (Dr. David Julian) changed location and took a faculty position at another institution. He has been involved in setting up his new laboratory and is currently setting up and calibrating the proteomics assay equipment in preparation for batch analyses of the samples. A full-time technician is being hired to assist in these experiments. The anticipated start date for this technician is January 8, 2001.
Future Activities:
Phytoplankton. In concert with the zooplankton studies, we will continue monthly sampling of Suisun, San Pablo, and Central San Francisco Bays for physical variables (salinity, temperature, turbidity), nutrients, phytoplankton biomass and composition and productivity. We plan to complete mass spectrometry analysis of the light enhanced productivity experiments carried out during Year 1 and will continue to conduct these experiments in Year 2.
Zooplankton. We are going to try to estimate abundance of alternative food for the copepod Acartia sp., because chlorophyll appears not to be a very good predictor of egg production.
Larval Herring. Larval herring will be sampled in San Pablo Bay and Central Bay locations from November 2000 through May 2002. We will examine more closely the effects of season and location on larval herring condition, and their relationship to other biotic and abiotic indicators. This will lead to a better understanding of the causal mechanisms underlying the nutritional condition of the larval herring population specifically, and the bay ecosystem more generally.
Benthic Studies. We will continue to measure condition and glycogen of the key organisms at the three benthic sites. Based on our success at analyzing the benthic community at the Grizzly Bay site, we hope to lengthen the time period covered by the benthic community data at the San Pablo Bay station with samples that were previously collected by the USGS but never analyzed. A proposal for funding to do this work has been sent to the Environmental Services Section of the California Department of Water Resources, which conducts the long-term monitoring of the benthic community at this location. We will be presenting our preliminary data on benthic community change as a poster at the Interagency Ecological Program Annual Meeting in March 2001. This meeting includes all agencies, academic institutions, and private consulting companies interested in the San Francisco Bay Estuary and Delta. Due to the difficult taxonomic problems at the marine station, as described above, one of our key objectives will be to describe the benthic community at a minimum of one sample per month.
Stress Proteins. Sample of clams, larval herring and zooplankton will be collected and stored at -80?C. The scope of the proposed experiments will be expanded to include whole-proteome analyses of tissues. Recent advances in proteomics technology, and the availability of start-funds to purchase the necessary equipment and software, now enable us to analyze changes in expression and post-translational modification of all proteins in a given tissue sample, and not just HSPs and metallothioneins. The basic technology involves automated computer analysis of two-dimensional electrophoretic gels. This will significantly increase the data obtained from the tissue samples.
Journal Articles:
No journal articles submitted with this report: View all 53 publications for this projectSupplemental Keywords:
marine, estuary, ecological effects, organism, ecosystem, indicators, biology, aquatic, ecology, monitoring, analytical, western, pacific coast, California, CA, phytoplankton, zooplankton, benthos, morphometrics., RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Ecology, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Chemistry, State, Microbiology, Ecological Effects - Environmental Exposure & Risk, EPA Region, aquatic ecosystem, environmental monitoring, nutrient supply, EMAP, marine ecosystem, Region 9, stressors, trophic transfer, bioavailability, phytoplankton dynamics, ecosystem indicators, salinity, bioindicators, aquatic ecosystems, benthos-associated organisms, San Franciso Estuary, ecological indicators, California (CA), benthic nutrients, populationRelevant Websites:
http://userwww.sfsu.edu/~aarp/arp-lab.html Exit
http://userwww.sfsu.edu/~bioocean/research/epaherring/epaherring.html Exit
http://userwww.sfsu.edu/~phytopl/ Exit
http://www.zoo.ufl.edu/julian/ Exit
http://online.sfsu.edu/~kimmerer/research.htm Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.