UC Marine Council

Elements incorporated into developing hard parts of planktonic larvae record the environmental conditions experienced during growth. These chemical signatures, termed elemental fingerprints, potentially allow for reconstruction of locations of larvae. Here, we have demonstrated for the first time the feasibility of this approach for bivalve shells. We have determined the spatial scale over which we are able to discriminate chemical signatures in mussels in southern California and characterized the temporal stability of these signals. Early settlers of Mytilus californianus and Mytilus galloprovincialis were collected from eight sites in southern California. Shells were analyzed for nine isotopes using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). We discriminated among mussels collected in two bays and the open coast using Mn, Pb, and Ba shell concentrations. Shell concentrations of Pb and Sr were sufficiently different to discriminate between mussels from the northern and southern regions of the open coast, each representing approximately 20 km of coastline. These signals were relatively stable on monthly and weekly time scales. These results indicate that trace elemental fingerprinting of shell material is a promising technique to track bivalve larvae moving between bays and the open coast or over along-shore scales on the order of 20 km. Identification of spatial variation in elemental fingerprints that is stable over time represents a crucial step in enhancing our ability to understand larval transport and population connectivity in invertebrates.

For California sea lions (Zalophus californianus), a dominant species on the California coast, understanding foraging is essential for understanding impact of population growth on the coastal environment. California sea lion numbers have increased steadily at a rate of 5% from the mid 1970's to 1995. In recent years, the populations have expanded at a rate of 6.2%. The impact of this increase on the surrounding environment is not completely understood. Conversely, the conflict between fisheries and sea lions over a limited resource is evident. Negative effects are apparent on both sides, from monetary loss to potential loss of a sustainable resource for fishermen and injury to mortality for the sea lions. By locating precise feeding areas, there is the potential for wildlife managers to reduce or avoid these interactions in the future. In addition, by understanding the rate of consumption of these animals, researchers can better predict the impact on the fish stock and environment that will result as this population growth continues.

Stomach temperature technology provides a tool to better understand the foraging behavior of California sea lions. Using adult females from the Channel Islands population tagged with satellite tags, time-depth recorders, and stomach temperature telemetry, we will attempt to precisely identify when and where foraging occurs. These data will also be used to obtain an estimate of foraging efficiency (catch per unit time) and time spent foraging. These measures of foraging success will be a key factor in recognizing the impact of pinnipeds in the marine environment and promising tool to monitor population status. As California sea lion populations increase, estimates of foraging efficiency will provide valuable information to predict the current and future effects on the coastal environment.

Several species of rockfish currently suffer from overfishing in California and remediation is required to replenish depleted stocks. Due to precipitous declines in several species, it is clear that both managers and research must focus on clarifying population dynamics and spatial connectivity of rockfish populations. All aspects of fisheries management, including ecosystem-based fisheries management tools, require knowledge of the spatial scale of genetic exchange or movement of individuals among populations and degree to which this renders stocks self-replenishing. Population genetics is one of few tools available that directly measures levels of connectivity among marine populations. My dissertation research examines genetic patterns and consequences of larval dispersal for two species of exploited rockfishes, blue and kelp rockfish, both of which inhabit nearshore rocky reefs and kelp forests along the California coast and are targeted by nearshore commercial live-fish and recreational fisheries. My goal is to characterize the effect of pelagic duration on the genetic structure of adults and of settling juveniles, and to analyze whether juveniles from different year-classes have similar patterns of genetic structure. I am using several microsatellite loci to analyze the population structure of young-of-the-year and adult rockfish. The high level of polymorphism inherent in microsatellite loci will provide a sensitive tool for finding subtle differences within and among adult samples and settling juveniles. By simultaneously describing the genetic structure of both juvenile year-classes and adult populations, this study will reveal much more about movement of larvae and constraints on reproductive output of adult populations than previous studies that have examined either larvae or adults alone. My dissertation research is designed to address critical questions on connectivity of rockfish in the coastal marine ecosystem, such that the results of this work can be directly applied to the management and conservation of exploited rockfish species.

Juvenile and adult Loligo opalescens Berry were video taped in Monterey Bay with the remotely operated vehicle (ROV) Ventana, captured with an otter trawl in Santa Monica Bay, California, and adults were taken from the Monterey Bay fishery. Behavioral observations were made over a 13·h period of video sequences. Allometry measurements were made on 157 squids ranging in size from 12 to 151·mm mantle length (ML). In addition to ML we measured the morphometric characters of fin length (FL), fin width (FW), mantle width (MW), eye diameter (ED), head width (HW), funnel aperture diameter (FA), fourth arm length (AL) and tentacle length (TL). Loligo opalescens changes shape with ontogeny due to negative allometric growth of ED, HW, TL, MW, FA and positive allometric growth of AL, FL and fin area. The allometry measurements were used to determine the size of juvenile squids video-taped in open water. A linear regression can predict dorsal ML in mm from a dimensionless ratio of ML upon ED (r2=0.857, P<0.001). Sizes and velocities of video-taped animals were estimated from 26 video sequences ranging from <1.0 to 8·s. The average velocity for squids ranging from 12–116 mm ML was 0.21·m·s–1 and the maximum velocity was 1.60·m·s–1 (116·mm·ML. Allometric measurements can provide scale for 2-dimensional images in order to estimate size, velocity and age of animals.

Mercury is a toxic that was mined in California’s Coast Range, and then used in the Sierra Nevada foothills for extraction of gold. Weathering of abandoned waste rock piles and mines, plus erosion of contaminated microorganisms, transform it into a more toxic form, methyl-mercury. This enters food chains where it bioaccumulates to concentrations that can cause impaired neurological function in a variety of higher organisms (fish, birds, humans). This toxic conversion has, in the scientific literature, been quite dogmatically attributed to activities of sulfate-reducing bacteria. Importantly, recent unpublished results from our laboratory with freshwater sediments show that iron-reducing bacteria can also convert inorganic mercury into methyl mercury, and do so at rates equivalent to those of sulfate-reducing bacteria. Due to California’s high concentration of iron in coastal sediments, we propose to test the hypothesis that iron-reducing bacteria also contribute significantly to the overall production of methyl mercury in marine sediments. We will do this by exploring the linkage between methyl mercury production and the activity of iron-reducing bacteria. In mercury-contaminated marine sediments, we will measure rates of methyl mercury production along with signature activities of different bacterial metabolic types, i.e. sulfate reduction and iron reduction. A second approach involves culturing evolutionarily diverse iron-reducing bacteria from contaminated marine sediments to compare (vs. sulfate-reducers) their relative abilities to methylate mercury. Understanding, based on potential in pure cultures and activities in contaminated sediments, which bacterial types contribute significantly to mercury methylation in coastal sediments will aid in modeling of marine methyl mercury problems, and in creating remediation strategies for impacted sites. This project also has implications for certain commercial fisheries that are impacted by bioaccumulation of methyl mercury.

We propose to establish, maintain, and augment the sensors for UCLA's oceanographic mooring near the edge of the continental shelf in Santa Monica Bay; extensively sample the water quality within the surrounding region, and interpret the measurements in combination with satellite sensing and three-dimensional, fine-scale numerical simulations of the local region. This will be done in coordination with other proposed measurements in the Southern California Bight that collectively are establishing a long-term, multi-purpose observing system for the regional environment. The research issues to be addressed with the measurements include water quality and pollution, ecosystem productivity, biogeochemical cycling, zooplankton and forage species distributions, mesoscale circulation patterns, and climate variability.

Nutrient loading from urban development and intensive agriculture can have a significant adverse impact on coastal environments. The focus of this research proposal is to (1) measure and characterize nutrient loading by landuse on a watershed scale to the near-shore coastal environment using representative watersheds in southern California; and (2) develop a model to predict future nutrient export from these watersheds resulting from projected changes in landuse. The model will be based on an integrated modular framework and should prove a useful tool in watershed planning and management. The selected study watersheds drained by Carpinteria and Franklin creeks are distinctive but regionally characteristic catchments. Santa Monica Creek, draining an adjacent catchment, will be used to test the portability of the model. Both Franklin and Santa Monica Creeks carry a high nutrient load from urbanization and intensive agriculture to one of southern California's few remaining wetlands, the Carpinteria Salt Marsh (Ferren et al, 2000).

With an intensive sampling program throughout the wet and dry seasons, I will characterize nutrient loading by landuse type. Existing information on landuse, soils, geology, vegetation and basin hydrology will be gathered and structured in a geographical information system (GIS) database. This will guide the sampling strategy and provide basic data for determining export coefficients for various landuses. A nutrient export coefficient model (NEC-M) will be constructed and integrated with an existing urban growth model for the Santa Barbara area of California (SLEUTH/UCIME). The combined model will be used to predict nutrient export for various growth scenarios, which can be used to evaluate zoning and "best management practice" pollution control alternatives. In addition, the project results will provide important watershed discharge data for the Santa Barbara Coastal Long Term Ecological Research (SBC-LTER) project in a collaborative effort to understand the dynamics of near-shore oceanic water quality.

Dolphins and African apes are distantly related mammalian taxa that exhibit striking convergences in their socioecology. In both cetaceans and African apes, two or more closely related species sometimes occur in sympatry. However, detailed reviews of the ways in which sympatric associations of dolphins and apes are similar have not been done. As fi eld studies of dolphins and apes have accumulated, comparisons of how the two groups avoid direct food competition when in sympatry have become possible. In this paper we review sympatric ecology among dolphins and African apes, and examine convergences in species-associations in each taxa. We review evidence for hypotheses that seek to explain avoidance of food competition, and consider whether ape-dolphin similarities in this area may be related to the way in which social groups in both taxa optimally exploit their food resources.

Anthropogenic nutrient enrichments can have a significant effect on the redox state in estuarine systems. Increased nutrient `loading' leads to higher productivity and a subsequent increase in organic matter sedimentation. Respiration of this organic matter consumes dissolved oxygen, sometimes leading to hypoxic conditions in overlying water. Nutrients and toxins can then be released from the sediments to bottom waters, leading to catastrophic fish kills during overturn events.

My thesis work is focused on defining the relationship between organic carbon burial and redox state (relative progress of oxidation and reduction reactions) in sediments of estuarine systems in coastal California. Reduced species other than organic carbon are produced in sediments by organic carbon oxidation. This is important because alteration of the redox balance in estuarine sediments has a direct effect on dissolved oxygen concentrations of overlying waters, which have been identified by the National Estuary Program as one of the most important factors determining the health of estuarine ecosystems.

I will focus on characterizing the sedimentary redox conditions of two California estuaries using an automated Combustion Oxygen Demand Instrument (COxD): San Francisco Bay, a heavily impacted system, and Elkhorn Slough, a more pristine system. This work will contribute to understanding the importance of redox state in assessment and planning for the future of highly impacted estuaries such as the San Francisco Bay, and may help assess the success of restoration efforts of more pristine coastal wetland regions, such as Elkhorn Slough. Unique data produced as part of my thesis work will contribute to a new understanding of anthropogenic alteration of estuarine ecosystems and effects on coastal water and sediment quality. This work addresses the delicate balance of sustainable human progress and conservation of ecosystems vital to maintaining habitat and biodiversity in the California coastal zone.