Recent ucmarine_ceqi items

Pinniped ecology in Santa Monica Bay, California

Tue, 22 Jul 2008 00:00:00 +0000

We investigated pinniped ecology at sea in Santa Monica Bay, California. Animals were studied during 277 boat-based surveys conducted in 1997-2007 documenting that California sea lion Zalophus californianus was the most observed species (89%, n sightings = 1393), followed by harbor seal (Phoca vitulina richardsi: 8%, n sightings = 131), and northern elephant seal (Mirounga angustirostris: 1%, n sightings = 15). Sea lions, and occasionally harbor seals, were found in aggregations with bottlenose dolphins Tursiops truncatis in 29% of the sightings (n bottlenose dolphin sightings = 205), short-beaked common dolphins Delphinus delphis and long-beaked common dolphins D. capensis in 53% of the sightings (n common dolphins = 155). Sea lions and harbor seals were regularly observed in coastal waters (shore) but also in the entire bay, with both species showing a preference for submarine...

Dolphins and African apes: comparisons of sympatric socio-ecology

Tue, 15 Jul 2008 00:00:00 +0000

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.

California Sea Lions Use Dolphins to Locate Food

Fri, 11 Jul 2008 00:00:00 +0000

Aggregations by 3 species of dolphins (the bottlenose dolphin [Tursiops truncatus], the short-beaked common dolphin [Delphinus delphis], and the long-beaked common dolphin [Delphinus capensis]) and California sea lions (Zalophus californianus) were investigated in Santa Monica Bay, California. Groups were followed and observed during 201 boat-based surveys conducted in 1997–2001 documenting that sea lions were aggregated in 18.6% of the sightings with bottlenose dolphins (150 bottlenose dolphin sightings) and in 45.9% of the sightings with 1 of the 2 species of common dolphins (98 common dolphin sightings). Aggregations of bottlenose dolphins and sea lions were observed in inshore (,500 m from shore) and offshore (.500 m) waters, whereas common dolphins and sea lions were observed only in offshore waters. These aggregations were often recorded feeding near escarpments and submarine canyons, showing a striking preference for these bathymetric...

Defining the Extent of Larval Exchange among Kelp Rockfish (Sebastes atrovirens) Populations Using Otolith Microchemistry

Mon, 5 Feb 2007 00:00:00 +0000

Defining the Extent of Larval Exchange among Kelp Rockfish (Sebastes atrovirens) Populations Using Otolith Microchemistry

Availability, usage and expected contribution of potential nursery habitats for the California halibut

Tue, 30 Jan 2007 00:00:00 +0000

Over the last several decades, human alterations have greatly changed the face of the California coastal zone, including the widespread loss of estuaries. The California halibut, Paralichthys californicus, is an ecologically and economically important finfish, and is known to depend upon inshore waters for nursery grounds. However, it remains poorly understood as to which specific habitat types (open coast, enclosed bays and estuaries, small lagoons) are most important as productive nursery grounds. In light of continued coastal change, information is needed on the relative importance of nursery habitat types for the proper implementation of marine reserves designed to protect the halibut.

The contribution of nursery habitat types will be determined using trace element analysis of California halibut otoliths (ear bones). These elements can be viewed as signatures that serve as a record of the environmental conditions experienced by fish over time and which differ...

Environmental Monitoring and Assessment of Environmental Estrogens in Marine

Wed, 13 Dec 2006 00:00:00 +0000

Unregulated organic compounds (aka Pharmaceuticals and the active ingredients in personal care products) have recently been detected in surface and drinking waters throughout the United States. The most biologically potent compounds in this group of compounds are the estrogenic steroids and other estrogen mimicking compounds that target the endocrine systems of fish and wildlife. Little is known about the concentrations or the effects of these compounds on marine fisheries in the United States. Preliminary studies from our laboratories in flatfish collected from Southern California have indicated potential endocrine disruption, as male fish were shown to have equivalent concentrations of blood egg yolk protein as those observed in female fish. The specific aims of this proposal are to identify the concentrations of likely active compounds, as well as potential uncharacterized compounds using a combined analytical chemistry and bioassay approach. The latter method will...

Spatial and temporal variation in trace elemental fingerprints of mytilid mussel shells: A precursor to invertebrate larval tracking

Wed, 13 Dec 2006 00:00:00 +0000

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...

Contribution of Iron-Reducing Bacteria to Mercury Methylation in Marine Sediments

Wed, 13 Dec 2006 00:00:00 +0000

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...

Speciation and Genetic Structure in a Marine Fish with an Extended Pelagic Larval Phase: an Analysis of Both the Juvenile and Adult Populations of Blue Rockfish (Sebastes Mystinus)

Wed, 13 Dec 2006 00:00:00 +0000

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...

Aspects of the ecology and behaviour of bottlenose dolphins (Tursiops truncatus) in Santa Monica Bay, California

Mon, 20 Mar 2006 00:00:00 +0000

The occurrence, distribution, site fidelity, group size and behaviour of common bottlenose dolphins (Tursiops truncatus) were assessed during a photo-identification study conducted between 1997-2001 in Santa Monica Bay, California. Bottlenose dolphins occurred yearround in the bay and were encountered on 56.8% of all surveys (n, total surveys=211). This species was found in waters within 0.5km of shore in 80.0% of the sightings (n=157), but sometimes found in deeper waters further offshore (>0.5km). No correlations between anomalies in sea surface temperatures during the 1997-98 El Niño event and sighting frequencies were observed. Group sizes varied significantly between schools observed inshore and offshore in the bay, with the largest groups sighted offshore. A total of 290 dolphins were individually photo-identified based on long-term natural marks on their dorsal fins. Forty-four individuals (15.2%) were encountered in both inshore and offshore waters, showing no exclusive...

Dolphin sympatric ecology

Mon, 20 Mar 2006 00:00:00 +0000

Interspecific associations between two or more species of the family Delphinidae have been reported by many scientists, but the sympatric ecology of such dolphin associations has not been studied in great detail. A few field investigations have been conducted on this subject in different parts of the world on species such as bottlenose dolphins (Tursiops spp.), short-beaked common dolphins (Delphinus delphis ), and killer whales Orcinus orca ). Sympatric dolphins seem to use different strategies to co-exist when resources appear to be limited, including dietary divergence (different prey preference, slightly diverse diet,different feeding time) and/or different habitat use shallow versus deep waters, flat areas versus submarine canyons and escarpments, different travel routes). This paper presents a review of some well-studied dolphin species found in sympatry and discusses the nature of habitat and resource partitioning as well as studies on aggressive behaviour displayed...

Larval Pathways and Population Connectivity in Nearshore Marine Organisms

Thu, 2 Feb 2006 00:00:00 +0000

One of the least understood and most fundamental processes in marine ecology is dispersal, or transport of larvae. To what extent are local adult population dynamics influenced by the dispersal of larvae from neighboring source populations? Do self-recruiting populations exist? How far do larvae disperse? The sources and destinations of larvae have been unknown for nearly all commercially important species, yet any model of resource management or biodiversity preservation depends on this information. We wish to understand the interdependency of commercially important California coastal populations by identifying the sources of larval recruits. To do this, we will use environmental signatures, consisting of trace metal inclusions in the hard structures of larvae (e.g., fish otoliths) that are laid down over time. Elements from the surrounding seawater become permanently incorporated into the structures, which then act as daily recorders of the environment experienced...

Macrozooplankton Assemblages in California Fronts

Tue, 24 Jan 2006 00:00:00 +0000

Coastal fronts are zones of intense biological activity, often defined by a narrow band of flotsam resulting from the convergence of two water masses. The accumulation of zooplankton at fronts has been reported many times in the literature, and is assumed to be the result of passive advection acting on organisms that lack the ability to swim effectively against currents. However, literature on zooplankton swimming behavior,specifically that pertaining to diel vertical migration, demonstrates that certain plankton groups are capable of swimming well over one hundred meters per hour. High rates of primary production are known to occur at fronts, and any behavior by zooplankton that would enhance the movement to and subsequent maintenance in these food sources should be conserved. However, it is unclear whether or not zooplankton aggregations at fronts are controlled exclusively by physical factors, or if behavior plays any role. The focus of this project is to quantify zooplankton...

Allometry measurements from in situ video recordings can determine the size and swimming speeds of juvenile and adult squid Loligo opalescens (Cephalopoda: Myopsida)

Fri, 20 Jan 2006 00:00:00 +0000

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...

Habitat Partitioning by Three Species of Dolphins in Santa Monica Bay, California

Fri, 20 Jan 2006 00:00:00 +0000

Despite scientific advances and increases in public interest in whales and dolphins, much information is still lacking to properly understand these animals living in an environment often threatened by human activities. Previously not investigated, the Santa Monica Bay is a heavily impacted area occupied year-round by various marine mammals, including threatened species. The purpose of this proposal is to provide a means to fill the need for critical information in the area.

This study takes a “precautionary approach” which may identify potential problems thereby preventing the disappearance of this and other species from the Bay. Project methodology involves weekly field surveys from a powerboat using laptop data collection, photo- and video-recording, plankton net tows, GIS, remote biopsy sampling, and a recently developed “computer-assisted system” for use in identifying dolphins.

By building upon research begun in 1996, this project will provide an important...

Coastal Ocean Observing System Elements for the Southern California Bight and Santa Monica

Fri, 20 Jan 2006 00:00:00 +0000

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.

The fishery for California market squid (Loligo opalescens) (Cephalopoda: Myopsidafrom 1981 through 2003

Fri, 20 Jan 2006 00:00:00 +0000

The California market squid (Loligo opalescens) has been harvested since the 1860s and it has become the largest fishery in California in terms of tonnage and dollars since 1993. The fishery began in Monterey Bay and then shifted to southern California, where effort has increased steadily since 1983. The California Department of Fish and Game (CDFG) collects information on landings of squid, including tonnage,location, and date of capture. We compared landings data gathered by CDFG with sea surface temperature(SST), upwelling index (UI), the southern oscillation index (SOI), and their respective anomalies. We found that the squid fishery in Monterey Bay expends twice the effort of that in southern California. Squid landings decreased substantially following large El Niño events in 1982−83 and 1997−98, but not following the smaller El Niño events of 1987 and 1992. Spectral analysis revealed autocorrelation at annual and 4.5-year intervals (similar to the time period between...

The effects of runoff on the physiology of Enteromorpha intestinalis: implications for use as a bioindicator of freshwater and nutrient influx to estaurine and coastal areas

Thu, 21 Jul 2005 00:00:00 +0000

Southern California is a highly populated region with developed watersheds. Thus there is increased risk of pollution reaching coastal waters and estuaries: more runoff reaches marine environments in urbanized areas, and there is year-round influx of treated wastewater effluent entering a system typically exposed to freshwater during the rainy season. A major limitation of current methods of freshwater and nutrient measurement is the samples are discrete. Therefore an integrative way to quantify terrestrial inputs to marine communities is necessary. The green macroalga Enteromorpha intestinalis has the potential to be an indicator of water quality. This alga is tolerant of a variety of environmental conditions and responds to decreased salinity and increased nutrient supply on the cellular level.

The focus of this project is to quantify the response of E. intestinalis to factors associated with terrestrial influx of freshwater and nutrients in order to assess its usefulness...

Human and Natural Causes of Variation of Forage Species on Nearshore Rocky Reefs

Thu, 21 Jul 2005 00:00:00 +0000

Rocky reefs along the coast of California provide important habitat for at least 125 species of fish, yet they are heavily impacted by humans. These reefs are naturally dynamic and can change from a forested state with many fish, dense stands of giant kelp and foliose algae and abundant forage food for fish, to unforested "barrens" that are generally lacking in kelp, macroalgae, fish and their forage food. Despite its name, a "barren" reef can support a diversity of habitat types, including patches containing understory foliose algae that harbor small invertebrates used by many fish for food. Depth, rates of sedimentation, topography and other physical factors can be responsible for some of this spatial variation. However, variation in intensity of grazing, mediated by refuges for algae from urchins, could also permit algae to persist on heavily grazed reefs. This proposal outlines research that seeks to identify the natural and anthropogenic factors that influence the distribution...

Assessing Human Alterations to Fluvial Sediment Delivery and the Impacts to Beach Sustainability, Central California

Thu, 21 Jul 2005 00:00:00 +0000

With the passage of Assembly Bill 64, the California Public Beach Restoration Act, in 1999, the State of California made its first enduring commitment to public beach nourishment. While ephemeral beach erosion and storm wave inundation of coastal properties occur frequently, particularly during the last two major El Niño events, there have been no comprehensive studies to date of regional beach changes documenting long-term trends of erosion that would justify artificially adding sand to California's beaches. Before the state embarks on an expensive program to augment the natural sediment supply, we need to understand how watershed development has altered natural sand delivery to the coast and how beaches have responded historically to variations in sand supply. In the watersheds draining to the central California coast between San Francisco and Monterey, 58 dams impound more than 2,600 km2 (or 15%) of watershed area. In the Santa Cruz Mountains, nearly 500 km2 of redwood and...

Genetic diversity enhances the resistance of a seagrass ecosystem to disturbance

Thu, 21 Jul 2005 00:00:00 +0000

Seagrasses and related aquatic vegetation have declined extensively in the U.S. and worldwide in recent years due to habitat degradation and reduced water quality. More importantly, over 90% of coastal wetlands have been destroyed in many regions of California. In light of this decline and the recognized importance of eelgrass populations to the overall health of coastal systems, there is a significant need to understand patterns of genetic variation in these populations. This information is critical to assessing the ecological interactions among eelgrass and its associated species. Furthermore, due to the priority of these systems for restoration and conservation projects, research examining the role of genetic diversity in ecosystem function is vital to ensure the success of these attempts and the future health of Z marina populations. To address these goals, I will evaluate patterns of genetic variation within and among eelgrass populations. This information will then...

A Dynamic Approach to the Characterization of Marine Habitats

Thu, 21 Jul 2005 00:00:00 +0000

The management of California's coastal resources, particularly nearshore fisheries, is increasingly recognizing the importance of protecting key habitats. The challenge that is emerging is how can we characterize marine habitats? The answer is not simple, since marine habitats include both a substrate and a water column component. Regardless of the substrate affinities of a target species, its performance and dynamics will be linked to characteristics of the surrounding water column. The pelagic component of the habitat sets many physical characteristics, determines the availability of planktonic food, and commonly plays a key role in the delivery of young. Describing habitats solely on the basely of the bottom characteristics is clearly insufficient. Yet, to date habitat descriptions and characterization of essential species habitats include at most only rudimentary characteristics of the water column such as depth.

Here I propose a new approach that applies modern statistical...

Facilitation Between Non-indigenous Species: Smooth Cordgrass and Invertebrates

Wed, 20 Jul 2005 00:00:00 +0000

Non-indigenous species threaten California’s coastal quality through impacts on habitat structure, migratory species, and commercial fisheries. Atlantic smooth cordgrass (Spartina alterniflora) has invaded San Francisco Bay, and is poised to invade other central coast marshes. It fills in mudflats used by migratory shorebirds and may change the invertebrate prey available to them as well. Some evidence suggests that non-indigenous species, such as smooth cordgrass, may change their surrounding habitat by changing physical structure or soil chemistry in a way that helps other non-indigenous organisms survive at the expense of native species, a process termed facilitation. However, there has been little quantitative work on facilitation. This study examines the effects of smooth cordgrass on invertebrates in San Francisco Bay, and may help predict its future impact in other marshes. My project uses both observational and manipulative methods, including measures of vegetation...

Trophically Transmitted Parasites as Wetland Assessors

Wed, 20 Jul 2005 00:00:00 +0000

There is currently a dire need to assess the ecological function of our state's few remaining wetlands. The parasitic communities of larval trematodes that live within the abundant horn snail (Cerithidea californica) have shown great promise in serving as robust indicators of the community diversity and trophic functioning of wetlands. The snails and their parasites are easily sampled and this tool may prove to be a better alternative or complement to the extremely burdensome standard wetland assessment techniques. The ultimate goal is to be able to look at the details of snail parasite community structure at a site and strongly infer the status of the rest of the wetland community. We see great variation in snail parasite community structure between sites within wetlands. Much of this variation is assumed to be due to variation in bird and mammal site use. This is because various species of birds and mammals serve as final hosts for these complex lifecycle parasites and the...

Evaluating the Relative Importance of Coastal Habitat Types as Productive Nursery Grounds for the California Halibut

Wed, 20 Jul 2005 00:00:00 +0000

The Effect of Rock Type on Intertidal Community Structure

Wed, 20 Jul 2005 00:00:00 +0000

Despite its significance and protected status, the intertidal region is being increasingly impacted by human activities such as harvesting, trampling, disposal of effluents and development. Major coastal engineering projects in Santa Cruz County armor eroding cliffs to stabilize the shoreline, reducing sand production and the amount of native substrate available for intertidal flora and fauna. The extensive anthropogenic armoring of the shorelines provides an unusual opportunity to determine the effect of differing rock types on intertidal community assemblages and sets the stage for experiments in the field. The goals of this project are: 1) to determine if rock type influences zonation patterns, 2) to determine if there is a difference in community assemblages relating to different rock types, 3) to demonstrate the mechanism responsible for these differences, and 4) attempt to link those patterns to life history characteristics. My approach is to characterize physical...

Fertilization in the sea: Establishing the minimum population sizes and environmental conditions for successful fertilization in abalone