Editors: P. Grifman, J. Hart, C. Stevenson
Author: C. Stevenson
USCSG-TR-02-2012 - PDF
Author(s): Emily A. Smail, Eric A. Webb, Robert P. Franks, Kenneth W. Bruland and Sergio A. Sañudo-Wilhelmy
doi/10.1021/es2023913 - Link
In order to establish the status of metal contamination in surface waters in the coastal ocean off Los Angeles, California, we determined their dissolved and particulate pools and compared them with levels reported in the 1970s prior the implementation of the Clean Water Act. These measurements revealed a significant reduction in particulate toxic metal concentrations in the last 33 years with decreases of100-fold for Pb and 400-fold for Cu and Cd. Despite these reductions, the source of particulate metals appears to be primarily anthropogenic as enrichment factors were orders of magnitude above what is considered background crustal levels. Overall, dissolved trace metal concentrations in the Los Angeles coastal waters were remarkably low with values in the same range as those measured in a pristine coastal environment off Mexico's Baja California peninsula. In order to estimate the impact of metal contamination on regional phytoplankton, the internalization rate of trace metals in a locally isolated phytoplankton model organism (Synechococcus sp. CC9311) was also determined showing a rapid internalization (in the order of a few hours) for many trace metals (e.g., Ag, Cd, Cu, Pb) suggesting that those metals could potentially be incorporated into the local food webs.
Author(s): Steven L Manley and Christopher G. Lowe
doi/10.1021/es203598r - Link
The Fukushima Daiichi Nuclear Plant, damaged by an earthquake and tsunami on March 11, 2011 released large amounts of 131I into the atmosphere, which was assimilated into canopy blades of Macrocystis pyrifera sampled from coastal California. The specific activity calculated to the estimated date of deposition/assimilation ranged from 0.6 to 2.5 Bq gdwt–1, levels greater than those measured from kelps from Japan and Canada prior to the release. These 131I levels represent a significant input into the kelp forest ecosystem. Canopy-forming kelps are a natural coastal dosimeter that can measure the exposure of the coastal environment to 131I and perhaps other radioisotopes released from nuclear accidents. An organizational mechanism should be in place to ensure that they are sampled immediately and continuously after such releases.
Author(s): K. E. Jirik and C. G. Lowe
doi/10.1111/j.1095-8649.2011.03208.x - Link
The habitat use and movements of the round stingray Urobatis halleri were compared between shallow restored and natural habitats of the Anaheim Bay Estuary (CA, U.S.A.) in relation to water temperature. Restored habitat remained significantly warmer than natural habitat from spring through to autumn. Strong sexual segregation occurred in the restored habitat with mature female U. halleri forming large unisex aggregations in summer, during months of peak seasonal water temperatures, and males only present during spring. Most mature females collected from restored habitat during months of high abundance were determined to be pregnant using non-invasive field ultrasonography. Tagged females typically spent <14 days in the restored habitat, using the habitat less as seasonal water temperatures decreased. Females tended to emigrate from the estuary by mid-August, coinciding with the time of year for parturition. The elevated water temperatures of the restored habitat may confer an energetic cost to male U. halleri, but females (particularly pregnant females) may derive a thermal reproductive benefit by using warm, shallow habitats for short periods of time during months of peak water temperatures. These findings have management implications for the design of coastal habitat restoration projects and marine protected areas that incorporate thermal environments preferred by aggregating female elasmobranchs.
Author(s): Thomas J. Farrugia, Mario Espinoza and Christopher G. Lowe
USCSG-R-06-2011 - Link
Coastal elasmobranchs such as the shovelnose guitarfish (Rhinobatos productus) seasonally use bays and estuaries for mating, pupping and feeding. However, many human-populated coastal areas have been developed, making them unavailable to coastal fish populations. The Full Tidal Basin (FTB) of the Bolsa Chica Ecological Reserve, California, USA, was completed in 2006, with the aim to restore lost estuarine habitat in southern California. Monthly abundance surveys conducted inside the FTB between June 2008 and September 2009 showed that shovelnose guitarfish were present throughout the year. Over 96% of the individuals caught were juveniles and these were most abundant in waters between 208C and 248C. Concurrently, 23 shovelnose guitarfish were fitted with coded acoustic transmitters and continuously tracked within the FTB for 16 months. Telemetry data showed individuals remained inside the FTB for, on average, 73.9 days (range 15–172 days), and made few movements between the FTB and the ocean. Tagged individuals disproportionately used mud habitats and waters at temperatures of 228C, both of which are more common in the FTB than the neighboring coastal ocean. The present study examined the structure and functionality of a restored estuary and suggests that the FTB is important habitat for a benthic predator, a promising result three years after restoration.
Author(s): Isabel C. Romero and Sarah J. Feakins
USCSG-R-04-2011 - Link
Coastal salt marsh ecosystems contain strong environmental gradients that are anticipated to influence the D/H ratios recorded in the leaf waxes of salt-tolerant plants. We characterized the molecular and hydrogen isotopic composition of alkanes in plant and sediment samples as well as the D/H ratios of environmental and plant waters across an elevation and inundation gradient in a southern Californian, coastal salt marsh. We sampled the dominant salt marsh plant species: Salicornia virginica, Arthrocnemum subterminale and Jamuea carnosa (all succulents), as well as Monanthochloe littoralis and Limonium californicum (nonsucculents). Plant xylem water hydrogen isotopic compositions indicate a shift in source waters from meteoric influences at upland sites (δD value –20‰) to seawater dominated values (0‰) at lowland areas. We found leaf water D enrichment relative to xylem water ranging from mean δD values of +54‰ (upland) to +28‰ (lowland), interpreted as a reduction of transpiration with increasing inundation time. This has the effect of increasing the net fractionation between source water and leaf wax product across the environmental gradient from mean values of –101‰ (upland) to –134‰ (lowland), with an attenuated signal recorded in the δD values of plant leaf wax n-alkanes (–122‰to –136‰). These results constrain the hydrogen isotopic composition of salt marsh organic matter that may contribute to marine carbon budgets of the Santa Barbara Basin, and further indicate the potential for plant leaf waxes to resolve paleoenvironmental change, including sea level change, in sediment cores from salt marsh ecosystems.
Author(s): Mario Espinoza, Thomas J. Farrugia, Dale M. Webber, Frank Smith, Christopher G. Lowe
USCSG-R-02-2011 - Link
The evolution and improvement of novel applications on acoustic telemetry technology are driven mainly by the need to address more complex behavioral, ecological and physiological questions. A new Vemco VR2W Positioning System (VPS) is described and tested here using an array of 16 VR2W acoustic monitoring receivers and 8 fixed synchronizing transmitters. VPS positioning algorithm is based on the 3-receiver time-difference-of-arrival (TDOA) algorithm used by the existing Vemco VRAP system, extended to work with an array of three or more receivers that do not have synchronized clocks. The positional accuracy and performance of the VPS was estimated on a stationary and a slow-moving coded transmitter, and on two free-swimming elasmobranch species. Mean positional accuracy (±SD) of VPS estimates from a stationary transmitter deployed at several locations within the receiver array was 2.64 ± 2.32 m. Positional error was significantly lower inside (2.13 ± 1.31 m) than outside the array (5.12 ± 4.11 m; p < 0001). There were no significant differences in positional accuracy between stationary and moving tests (4.09 ± 2.53 m; p = 0.067). Furthermore, home range estimates and movement parameters of two elasmobranch species tracked simultaneously with VPS and active tracking were statistically similar (p > 0.05). Our results suggest that the positional accuracy of the VPS is comparable to active tracking; however, researchers must consider specific environmental and biological variables when using the VPS. Additionally, the number, layout and proximity of acoustic receivers and synchronizing transmitters can improve considerably the performance of the VPS. The VPS provides a more efficient, less expensive approach to study and quantify fine-scale, long-term movements and habitat use of multiple individuals simultaneously, with the potential for improving our understanding on ecological and behavioral population level processes in aquatic environments.
Author(s): Jaime M. Sayre, Rachel G. Adams, Wenjian Lao and Keith A. Maruya
USCSG-R-06-2010 - PDF
Solid phase microextraction (SPME) fibers and low-density polyethylene (PE) passive samplers were co-exposed in spiked water experiments and in an impacted urban waterway to compare their performance in detecting ultra-trace levels of waterborne organic pollutants. Detections of nine model hydrophobic organic compounds (HOCs) using PE was greater than for SPME for spiked aqueous concentrations (Cw) less than 0.1 ng/L. The greater sensitivity of PE was confirmed in situ, with detectable levels as low as 1 pg/L for selected polychlorinated biphenyl (PCB) congeners. In laboratory studies, concentrations of targeted polycyclic aromatic hydrocarbons (PAHs), PCBs and chlorinated pesticides detected by SPME were within a factor of 2 on average to those measured using liquid-liquid extraction (LLE), while PE measurements were within a factor of 4 of LLE and were biased low, possibly due to uncertainties in PE equilibrium-partitioning coefficients. When in situ PE-measured concentrations were corrected for disequilibrium using performance reference compounds, the average ratio of SPME to PE for in situ concentrations was 1.8, indicating good overall agreement between the two passive samplers. In situ Cw values for SPME and PE were 70% (n = 4) and 210% (n = 6) on average of operationally dissolved Cw values determined on XAD resin with values for individual chemicals ranging from 20 to 140% (SPME/XAD) and from 27 to 590%. (PE/XAD). Although uncertainties (e.g., error associated with laboratory-measured equilibrium constants and corrections for disequilibrium) surrounding calibration parameters and equilibrium have not been fully resolved, these results indicate that both SPME and PE show promise as ambient sampling tools for contaminants of regulatory concern in the aquatic environment.
Author(s): Tom J. Mason and Christopher G. Lowe
USCSG-R-04-2010 - Link
Barred sand bass (Paralabrax nebulifer) is an important recreational species in southern California, which may benefit from marine protected areas. Understanding species movement patterns is a key component to identifying if a species will benefit from marine protected areas. Acoustic telemetry methods coupled with a GIS were used to quantify the home range, site fidelity, and habitat use of barred sand bass at the Catalina Marine Science Center Marine Life Refuge located at Santa Catalina Island, California. Barred sand bass utilized soft-sediment habitats within close proximity to rocky reefs and had home ranges that averaged 10,003m2 ±4773m2 (±SD). During the day, individuals generally used multiple areas on or near reefs, and at night repeatedly used one area over soft-sediment habitat. Fifty percent of the acoustically tagged individuals exhibited year round fidelity to the study site indicating that even small marine protected areas may be an effective management strategy.
Author(s): Tomašových, Adam; Kidwell, Susan M.
USCSG-R-03-2010 - Link
Patterns of low temporal turnover in species composition found within paleoecological time series contrast with the high turnover predicted by neutral metacommunity models and thus have been used to support non-neutral models. However, these predictions assume temporal resolution on the scale of a season or year, whereas individual fossil assemblages are typically time averaged to decadal or centennial timescales. We simulate the effects of time averaging by building time-averaged assemblages from local dispersal-limited, non-averaged assemblages and compare the predicted turnover with observed patterns in mollusk and ostracod fossil records. Time averaging substantially reduces temporal turnover such that neutral predictions converge with those of trade-off and density-dependent models, and it tends to decrease species dominance and increase the proportion of rare species. Observed turnover rates are comparable to an appropriately scaled neutral model: patterns of high community stability can be produced or reinforced by time averaging alone. The community attributes of local time-averaged assemblages approach those of the metacommunity. Time-averaged assemblages are thus unlikely to capture attributes arising from processes operating at small spatial scales, but they should do well at capturing the turnover and diversity of metacommunities and thus will be a valuable basis for analyzing the large-scale processes that determine metacommunity evolution.
Author(s): Tomašových, Adam; Kidwell, Susan M.
USCSG-R-02-2010 - Link
Although only a few studies have explicitly evaluated live-dead agreement of species and community responses to environmental and spatial gradients, paleoecological analyses implicitly assume that death assemblages capture these gradients accurately. We use nine data sets from modern, relatively undisturbed coastal study areas to evaluate how the response of living molluscan assemblages to environmental gradients (water depth and seafloor type; "environmental component" of a gradient) and geographic separation ("spatial component") is captured by their death assemblages. We find that:
Author(s): Tomašových, Adam; Kidwell, Susan M.
USCSG-R-01-2010 - Link
Despite extensive paleoecological analyses of spatial and temporal turnover in species composition, the fidelity with which time-averaged death assemblages capture variation in species composition and diversity partitioning of living communities remains unexplored. Do death assemblages vary in composition between sites to a lesser degree than do living assemblages, as would be predicted from time-averaging? And is the higher number of species observed in death relative to living assemblages reduced with increasing spatial scale? We quantify the preservation of spatial and temporal variation in species composition using 11 regional data sets based on samples of living molluscan communities and their co-occurring time-averaged death assemblages. (1) Compositional dissimilarities among living assemblages (LA) within data sets are significantly positively rank-correlated to dissimilarities among counterpart pairs of death assemblages (DA), demonstrating that pairwise dissimilarity within a study area has a good preservation potential in the fossil record. Dissimilarity indices that downplay the abundance of dominant species return the highest live-dead agreement of variation in species composition. (2) The average variation in species composition (average dissimilarity) is consistently smaller in DAs than in LAs (9 of 11 data sets). This damping of variation might arise from DAs generally having a larger sample size, but the reduction by ~10–20% mostly persists even in size-standardized analyses (4 to 7 of 11 data sets, depending on metric). Beta diversity expressed by the number of compositionally distinct communities is also significantly reduced in death assemblages in size-standardized analyses (by ~25%). This damping of variation and reduction in beta diversity is in accord with the loss of temporal resolution expected from time-averaging, without invoking taphonomic bias (from differential preservation or postmortem transportation) or sample-size effects. The loss of temporal resolution should directly reduce temporal variation, and assuming time-for-space substitution owing to random walk within one habitat and/or temporal habitat shifting, it also decreases spatial variation in species composition. (3) DAs are more diverse than LAs at the alpha scale, but the difference is reduced at gamma scales because partitioning of alpha and beta components differs significantly between LAs and DAs. This indicates that the effects of time-averaging are reduced with increasing spatial scale. Thus, overall, time-averaged molluscan DAs do capture variation among samples of the living assemblage, but they tend to damp the magnitude of variation, making them a conservative means of inferring change over time or variation among regions in species composition and diversity. Rates of temporal and spatial species turnover documented in the fossil record are thus expected to be depressed relative to the turnover rates that are predicted by models of community dynamics, which assume higher temporal resolution. Finally, the capture by DAs of underlying variation in the LA implies little variation in the net preservation potential of death assemblages across environments, despite the different taphonomic pathways suggested by taphofacies studies.
Bonnie L. Rogers, Christopher G. Lowe, Esteban Fernandez-Juricic, and Lawrence R. Frank
USCSG-R-02-2008 - PDF of entire paper, courtesy of Canadian Journal of Fisheries and Aquatic Sciences
The physical consequences of barotrauma on the economically important rocklish (Sebastes) were evaluated with a novel method using T2-weighted magnetic resonance imaging (MRI) in combination with image segmentation and analysis. For this pilot study, two fishes were captured on hook-and-line from 100 m, euthanized, and scanned in a 3 Tesla human MRI scanner. Analyses were made on each fish, one exhibiting swim bladder overinflation and exophthalmia and the other showing low to moderate swim bladder overinflation. Air space volumes in the body were quantified using image segmentation techniques that allow definition of individual anatomical regions in the three-dimensional MRIs. The individual exhibiting the most severe signs of barotrauma revealed the first observation of a gas-filled orbital space behind the eyes, which was not observable by gross dissection. Severe exophthalmia resulted in extreme stretching of the optic nerves, which was clearly validated with dissections and not seen in the other individual. Expanding gas from swim bladder overinflation must leak from the swim bladder, rupture the peritoneum, and enter the cranium. This MRI method of evaluating rockfish following rapid decompression is useful for quantifying the magnitude of intemal barotrauma associated with decompression and complementing studies on the effects of capture and discard mortality of rockfishes.
Lyall F. Bellquist, Christopher G. Lowe, Jennifer E. Caselle
© 2007 Elsevier B.V. All rights reserved.
USCSG-R-01-2008 - PDF
The fishery for California groundfishes is managed using broad species complexes, although some non-groundfish species are managed similarly due to the perception of shared behavioral characteristics. This study integrates acoustic telemetry and a GIS to quantify movement patterns of one such species, the ocean whitefish (Caulolatilus princeps) in a marine protected area. Seventeen ocean whitefish were tagged and actively tracked over multiple 24-h periods to measure fine-scale movement patterns. Home ranges based on 95% kernel utilization distributions averaged 20,439±28,492 (±S.D.)m2. Fish were active during the day, foraging over sand habitat at depths averaging 21±8m, but were inactive at night, taking refuge near rocky reefs at depths averaging 15±7m. Seventeen additional fish were tagged with coded acoustic transmitters and passively tracked using automated underwater acoustic receivers for up to 1 year. Approximately 75% of these fish exhibited long-term (1 year) fidelity to home ranges in the study area. Results suggest that MPAs can be an effective means of protecting populations of ocean whitefish and based on their habitat associations, ocean whitefish can be managed separately from other reef associated groundfishes.
Astrid Schnetzer, Peter E. Miller, Rebecca A. Schaffner, Beth A. Stauffer, Burton H. Jones, Stephen B. Weisberg, Paul M. DiGiacomo, William M. Berelson and David A. Caron
USCSG-TR-01-2008 - PDF
Abundances of Pseudo-nitzschia spp. and concentrations of particulate domoic acid (DA) were determined in the Southern California Bight (SCB) along the coasts of Los Angeles and Orange Counties during spring and summer of 2003 and 2004. At least 1,500 km2 were affected by a toxic event in May/June of 2003 when some of the highest particulate DA concentrations reported for US coastal waters were measured inside the Los Angeles Harbor (12.7 mg DA L-1). Particulate DA levels were an order of magnitude lower in spring of 2004 (February and March), but DA concentrations per cell at several sampling stations during 2004 exceeded previously reported maxima for natural populations of Pseudo-nitzschia (mean = 24 pg DA cell-1, range = 0 - 117 pg DA cell-1). P. australisdominated the Pseudo-nitzschia assemblage in spring 2004. Overall, DA-poisoning was implicated in >1,400 mammal stranding incidents within the SCB during 2003 and 2004. Ancillary physical and chemical data obtained during our regional surveys in 2004 revealed that Pseudo-nitzschiaabundances, particulate DA and cellular DA concentrations were inversely correlated with concentrations of silicic acid, nitrogen and phosphate, and to specific nutrient ratios. Particulate DA was detected in sediment traps deployed at 550 and 800 m depth during spring of 2004 (0.29 - 7.6 mg DA (g sediment dry weight)-1). The highest DA concentration in the traps was measured within one week of dramatic decreases in the abundances of Pseudo-nitzschia in surface waters.
Jonathan A. Warrick, Paul M. DiGiacomo, Stephen B. Weisberg, Nikolay P. Nezlin, Michael J. Mengel, Burton H. Jones, J.Carter Ohlmann, Libe Washburn, Eric J. Terrill and Katie L. Farnsworth
Stormwater river plumes are important vectors of marine contaminants and pathogens in the Southern California Bight. Here we report the results of a multi-institution investigation of the river plumes across eight major river systems of southern California. We used in situ water samples from multi-day cruises in combination with MODIS satellite remote sensing, buoy eteorological observations, drifters, and HF radar current measurements to evaluate the dispersal patterns and dynamics of the freshwater plumes. River discharge was exceptionally episodic, and the majority of storm discharge occurred in a few hours. The combined plume observing techniques revealed that plumes commonly detach from the coast and turn to the left, which is the opposite direction of Coriolis influence.
Although initial offshore velocity of the buoyant plumes was ~50 cm s-1 and was influenced by river discharge inertia (i.e., the direct momentum of the river flux) and buoyancy, subsequent advection of the plumes was largely observed in an alongshore direction and dominated by local winds. Due to the multiple day upwelling wind conditions that commonly follow discharge events, plumes were observed to flow from their respective river mouths to down-coast waters at rates of 20 - 40 km d-1.
Lastly, we note that suspended-sediment concentration and beam-attenuation were poorly correlated with plume salinity across and within the sampled plumes (mean R2 = 0.12 and 0.25, respectively), while colored dissolved organic matter (CDOM) fluorescence was well correlated (mean R2 = 0.56), suggesting that CDOM may serve as a good tracer of the discharged freshwater in subsequent remote sensing and monitoring efforts of plumes.
Erica T. Jarvis and Christopher G. Lowe
USCSG-R-03-2008 - PDF
Two experiments were used to assess initial capture survival and short-term post-release survival of line-caught (range 18 to 225 m) southern California rockfish following recompression. Occurrence of external and internal signs of barotrauma was characterized across all species. Despite species-specific differences in the extent of barotrauma observed, initial capture survival of 19 rockfishes held in a live well for a 10 min period following capture was 68% overall. Overall survival of 17 rockfishes following recompression in cages for two days was also 68%. Short-term survival varied across species (range 36% to 82%) as well as the occurrence of external signs of barotrauma. The degree of external signs of barotrauma was not a significant predictor of initial capture survival or short-term survival. The most significant predictor of short-term survival was surface holding time, with short-term survival increasing with decreasing surface holding time. These results suggest assisted release of rockfishes, with short surface holding times, can significantly increase post-release survival and could potentially enhance rockfish conservation.
Wytze T. Stam, Jeanine L. Olsen, Susan Frisch Zaleski, Steven N. Murray, Katherine R. Brown and Linda J. Walters
USCSG-R-03-2007 - Link
Baseline genotypes were established for 256 individuals of Caulerpa collected from 27 field locations in Florida (including the Keys), the Bahamas, US Virgin Islands, and Honduras, nearly doubling the number of available GenBank sequences. On the basis of sequences from the nuclear rDNAITS 1+2 and the chloroplast tufA regions, the phylogeny of Caulerpa was reassessed and the presence of invasive strains was determined. Surveys in central Florida and southern California of >100 saltwater aquarium shops and 90 internet sites revealed that >50% sold Caulerpa. Of the 14 Caulerpa species encountered, Caulerpa racemosa was the most common, followed by Caulerpa sertularioides, Caulerpa prolifera, Caulerpa mexicana, and Caulerpa serrulata. None of the >180 field-collected individuals(representing 13 species) was the invasive strain of Caulerpa taxifolia or C. racemosa. With one exception (a sample of C. racemosa from a shop in southern California belonged to the invasive Clade III strain), no invasive strains were found in saltwater aquarium stores in Florida or on any of the internet sites. Although these results are encouraging, we recommend a ban on the sale of allCaulerpa species (including ‘‘live rock’’) because: morphological identification of Caulerpa species is unreliable (>12% misidentification rate) and invasive strains can only be identified by their aligned DNA sequences, and because the potential capacity for invasive behavior in other Caulerpa species is far from clear. The addition of the Florida region to the genetic data base for Caulerpa provides a valuable proactive resource for invasion biologists as well as researchers interested in the evolution and speciation of Caulerpa.
Erica T. Jarvis
PDF of Thesis
Article in SLATE (A News Publication of the American Academy of Underwater Sciences)
Three experiments were used to assess initial capture survival, and short- and long-term post-release survival of line-caught (18 to 225 m) southern California rockfish following recompression. Initial capture survival of 19 rockfishes held in a live well for a 10 min period following capture was 68% overall (95% CI: 60% to 75%; n = 168). Two-day survival of 17 rockfishes following recompression in cages was also 68% overall (95% CI: 62% to 73%; n = 256). External and internal signs of barotrauma were not significant predictors of initial capture survival or short-term survival. The most significant predictor of short-term survival was surface holding time (logistic regression model:Χ 2 = 8.63, p = 0.003, OR = 0.95). Fish recaptures and 2-year monitoring data of acoustically tagged rockfish (n = 84) provided evidence of long-term post-release survival of rockfish of at least 690 days.
A. E. Parker, J. Fuller, R. C. Dugdale
USCSG-R-08-2007 - PDF
One of the most fundamental measurements used for characterizing marine environments is primary production, the production of organic matter from inorganic constituents (most commonly through photosynthesis). Primary production estimates are typically made using the radioactive carbon -14 tracer technique introduced by Steeman Nielsen (1952) where the investigator adds a trace amount of radioactive carbon to a water sample and quantifies the radioactive enrichment of particulate organic matter during an incubation period. The technique is dependent upon precise determination of both radioactive enrichment and ambient dissolved inorganic carbon (DIC) concentration in the sample. While determining radioactivity is relatively easy with the use of a liquid scintillation counter, direct determination of DIC concentrations is often more difficult as few laboratories have the necessary instrumentation available. Traditionally in oceanic studies, DIC concentrations were based on a constant approximate value of 2000 μmol L-1 (i.e. Eppley & Sharp, 1975; Sharp, personal communication, see “Notes”) or based on measurements of salinity and pH (Parsons et al., 1984). These methods of approximation can be made within a salinity range of 22 – 33 psu (Parsons et al., 1984) and are therefore of limited use for work in estuaries, such as the San Francisco estuary (SFE), where salinity varies between 0 and >33 psu. Previous 14C based estimates of primary production in the SFE required direct determination of DIC concentrations (e.g. Cole & Cloern, 1984, Jassby et. al.2002).
Richard C. Dugdale, Frances P. Wilkerson, Victoria E. Hogue, and Albert Marchi
USCSG-R-07-2007 - PDF
The substantial inventory of nitrate (NO3) in San Francisco Bay (SFB) is unavailable to the resident phytoplankton most of the year due to the presence of ammonium (NH4) at inhibitory concentrations that prevents NO3 uptake. Low annual primary productivity in this turbid estuary is generally attributed to the poor irradiance conditions. However, this may not be the only cause; spring phytoplankton blooms occur irregularly in north SFB only when NH4 concentrations are low, <4 μmol L−1 and NO3 uptake by phytoplankton occurs. Field measurements and enclosure experiments confirm the NH4 inhibition process to be the cause of low NO3 utilization most of the year. Detailed analysis of spring blooms in three embayments of SFB over 3 years shows a consistent sequence of events that result in bursts of chlorophyll. The first requirement is improved irradiance conditions through stabilization of the water column by stratification or reduced tidal activity. Second, NH4 concentrations must be reduced to a critical range, 1 to 4 μmol L−1 through dilution by precipitation and by phytoplankton uptake. This enables rapid uptake of NO3 and subsequent increase in chlorophyll. The resulting bloom is due to both the initial uptake of NH4 and the subsequent uptake of NO3. The NO3 uptake step is crucial since it is the larger nitrogen source and uptake occurs at higher rates than that for NH4 at the concentrations that occur in SFB. Existing models of light-limited, non-nutrient limited productivity in SFB require modification to include the NH4 inhibition effect. From measured NH4 uptake rates and initial concentrations, calculations can be made to predict the length of time that favorable irradiance conditions are required for the phytoplankton population to reduce ambient NH4 concentrations to non-inhibiting concentrations and allow bloom formation to begin. For Suisun Bay, the time required is so long that blooms are unlikely in any season. For San Pablo and Central Bays, these times are too long in summer but sufficiently short in spring to allow bloom development, depending on the ambient NH4 concentration prior to the productivity season. NH4 sources to SFB are primarily anthropogenic, from agricultural drainage and sewage treatment plants, and if not sufficiently diluted by runoff and precipitation can prevent development of the spring phytoplankton bloom. Attention should be paid to the form of N making up dissolved inorganic nitrogen (DIN) in nutrient-rich estuaries.
Barbara V. Hight, Christopher G. Lowe
USCSG-R-05-2007 - Link
The leopard shark, Triakis semifasciata, is an abundant nearshore elasmobranch, ranging from Baja California, Mexico to Oregon, USA. Mature female leopard sharks have been observed aggregating in shallow embayments throughout California; however, it is unclear why only females aggregate in these shallow areas. The goal of this study was to determine if mature female leopard sharks selectively occupy the warmest areas of a shallow embayment, if free-ranging leopard sharks' body temperatures are significantly warmer during the day than at night, and to quantify temporal use of these shallow habitats. Visual observations of sharks' fine-scale movements within the shallows of Big Fisherman's Cove Marine Life Refuge (Santa Catalina Island) aggregation site indicated that sharks preferred the warmest areas of the embayment and moved to warmer locations over the course of the day (p<0.05). Active and passive acoustic tracking, along with archival transponder technology (Vemco: V13, V13-R256, VX32TP-CHAT tags respectively) of 16 sharks caught and tagged within this aggregation were used to monitor core body temperature, swimming depth, and movements. Sharks had significantly higher core body temperatures in the late afternoon (1700 h–2000 h) during the summer, showed increased fidelity to thermal refuges during the day and increased movement away from these refuges at night (χ2, p<0.05). Seasonal variations in warm, shallow water usage were also observed. Elevated core body temperature of mature female leopard sharks using warm shallow embayments will likely augment metabolic and physiological functions such as digestion, somatic growth, and possibly reproduction.
Victor M. Galvan, Steven N. Murray
In the summer of 2000 Caulacanthus ustulatus was first observed in southern California waters. Since then, this species has become very abundant at several intertidal sites where it grows on articulated corallines, rockweed stipes, rock, mussel shells, and barnacles. Here we provide the first reports of the effects of temperature on dark respiration rates and the photosynthetic responses of southern California specimens of C. ustulatus. Maximum photosynthetic rates (P max) ranged from 4.54 (≠ 0.35 SE) to 3.75 (± 0.29) mg O2g-1 dwt h-1 but did not vary significantly (ANOVA; P = 0.29) over the tested temperatures (11, 14, 17 and 20 °C). Light-limited slopes (α) ranged from 0.0696 (± 0.01 SE) to 0.0582 (± 0.01) but also did not vary significantly (ANCOVA; P = 0.86) with temperature. Similarly, temperature had not significant effect (ANOVA; P = 0.46) on dark respiration rates, which ranged from 0.78 ± (0.16 SE) to 0.44 (± 0.11) mg O2g-1 dwt h-1 . Ic ranged from 12.8 (± 0.29 SE) at 17 °C to 7.1 (± 1.66) μmol m-2 s-1 at 11 °C. These data show that the photosynthetic performance of C. ustulatus is similar over the range of temperatures encountered in southern California and along the remainder of the California coast and suggest that C. ustulatus is able to grow and likely establish populations throughout the entire region.
Loraine F. Hale, John V. Dudgeon, Andrew Z. Mason, Christopher G. Lowe
USCSG-R-02-2007 - PDF
©Springer Science+Business Media B.V. 2006
Although numerous studies have utilized elemental analysis techniques for age determination in bony fishes, little work has been conducted utilizing these procedures to verify age assessments or temporal periodicity of growth band formation in elasmobranchs. The goal of this study was to determine the potential of laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) to provide information on the seasonal deposition of elements in the vertebrae of the round stingray collected from Seal Beach, California. Spatially resolved time scans for elements across the round stingray vertebrae showed peaks in calcium intensity that aligned with and corresponded to the number of seasonal growth bands identified using standard light microscopy. Higher signals of calcium were associated with the wide opaque bands while lower signals of calcium corresponded to the narrow translucent bands. While a close alignment between the numbers of calcium peaks and annual growth bands was observed in round stingray samples aged 5 years or younger, this relationship was less well defined in vertebral samples from round stingrays over 11 years old. To the best of our knowledge, this is the first study of its kind to utilize ICP-MS to verify age assessments and seasonal band formation in an elasmobranch. The results from this preliminary study indicate that LA-ICP-MS elemental analysis of the vertebral cartilage of the round stingray may have potential to independently verify optically derived age assessments and seasonal banding patterns in elasmobranch vertebrae.
Christopher G. Lowe, Greg J. Moss, Greg Hoisington, IV, Jeremy J. Vaudo, Daniel P. Cartamil, Megan M. Marcotte, and Yannis P. Papastamatiou
USCSG-R-01-2007 - PDF
Natural caudal spine replacement rates, population size and site fidelity of round stingrays, Urobatis halleri (Cooper), at Seal Beach, California were determined to evaluate the efficacy of clipping of caudal spines of stingrays to reduce injury to human beachgoers. Of the 2,183 stingrays caught, clipped, tagged, and released at Seal Beach, only 13 (0.06%) were recaptured over a threeyear period, indicating a large, mobile population. Natural spine replacement occurred between August–October, when a majority of rays were found with two spines. Monthly catch rates of rays were variable, but positively correlated with the number of injuries reported by beachgoers. There was no significant reduction in stingray-related injuries to beach goers at Seal Beach over the period when stingray caudal spine clipping was conducted.
Frances P. Wilkerson, Richard C. Dugdale, Victoria E. Hogue, and Albert Marchi
USCSG-R-05-2006 - PDF
J. Aaron Hipp, Oladele Ogunseitan, Raul Lejano, and C. Scott Smith
USCSG-R-04-2006 - Link
J. J. Vaudo, C. G. Lowe
USCSG-R-02-2006 - Link
Jed A. Fuhrman, Xiaolin Liang, and Rachel T. Noble
USCSG-R-01-2006 - Link
Heupel, Michelle; Simpfendorfer, Colin; Lowe, Christopher
USCSG-TR-01-2006 - Link
Jayson R. Smith, Steven N. Murray
USCSG-R-08-2005 - Link
Gregory Hoisington IV, Christopher G. Lowe
USCSG-R-07-2005 - Link
Phyllis Grifman and Judith Lemus
Paul M. DiGiacomo, Libe Washburn, Benjamin Holt and Burton H. Jones
USCSG-R-06-2005 - Link
John F. Griffith, Stephen B. Weisberg and Charles D. McGee
USCSG-R-05-2005 - Link
John F. Griffith, Stephen B. Weisberg and Charles D. McGee
USCSG-R-04-2005 - Link
Katharine G. Field, Eunice C. Chern, Linda K. Dick, Jed Fuhrman, John Griffith, Patricia A. Holden, Michael G. LaMontagne, Betty Olson, Michael T. Simonic
USCSG-R-03-2005 - Link
Petra K. E. Johansson, Thomas G. Douglass, and Christopher G. Lowe
USCSG-R-01-2005 - Link
T. O. Cho, S. Fredericq, S. N. Murray, S. M. Boo
USCSG-R-04-2004 - Link
C. C. Ouverney and J. A. Fuhrman
USCSG-R-13-2003 - Link
I. Hewson, G. A. Vargo, and J. A. Fuhrman
USCSG-R-12-2003 - Link
Rachel T. Nobel and Jed A. Fuhrman
USCSG-R-11-2003 - Link
Christopher G. Lowe, Darin T. Topping, Daniel P. Cartamil, Yannis P. Papastamatiou
USCSG-R-09-2003 - Link
Kido, J. S., Murray, S. N.
USCSG-R-05-2003 - Link
Elaine A. Logothetis
USCSG-TD-02-2003 - Link
Darryl R. Smith
Eddy Y. Zeng, Jian Pen, David Tsukada, and Teh-Lung Ku
USCSG-R-01-2003 - Link
Rodolfo Iturriaga, Sean Zhang, Gregory J. Sonek, and Henry Stibbs
USCSG-R-03-2001 - Link
See the review of this study from Biophotonics International
Murray, Steven N. et al.
Fisheries. (1999): 24(11): 11-25.
USCSG-R-01-2000 - Link