Acuna S.,University of California at Davis |
Deng D.-F.,Oceanic Institute |
Teh S.,University of California at Davis
Aquatic Toxicology | Year: 2012
The presence of the toxic cyanobacterium Microcystis in the upper San Francisco Estuary (SFE) since 1999 is a potential but to date an unquantified threat to the health and survival of aquatic organisms, such as fish and zooplankton. The microcystins (MCs) predominantly in the LR-form (MC-LR) contained in Microcystis is hepatotoxic and a potential threat to the fishery. This study was conducted to determine the effects of dietary exposure of the endemic Sacramento splittail, Pogonichthys macrolepidotus in SFE to Microcystis and its toxin, MC-LR. Juvenile splittail (12.59±0.7gfish -1) were exposed to five diets for 28d with MC-LR obtained from: (1) Microcystis harvested from the SFE and (2) a synthetic purified form of MC-LR. Three of the test diets contained 3.55 (D5), 9.14 (D10) and 17.13 (D20)mg MC-LRkg -1 from Microcystis. The other two diets contained either purified MC-LR at 3.89mg MC-LRkg -1 (D5R) or no MC-LR (D0). The RNA/DNA ratio of fish muscle was significantly lower for all treatments fed test diets containing MC-LR compared to the control diet D0, suggesting Microcystis adversely affected nutritional status. Protein phosphatase 2A expression in the fish from the D5, D10 and D20 treatments were inversely affected by increasing concentrations of MC-LR. Cytoplasmic inclusion bodies and single cell necrosis were more prevalent and greater in severity in the fish exposed to the diets D10 and D20 compared to fish from the D0 treatment and indicate severe liver toxicity in splittail exposed to MC-LR. The sublethal effects on splittail characterized by this study suggest cyanobacterial blooms have the potential to affect splittail nutritional status and health in SFE. © 2011 Elsevier B.V..
Huang S.S.Y.,University of California at Davis |
Strathe A.B.,University of California at Davis |
Wang W.-F.,Chinese Academy of Fishery Sciences |
Deng D.-F.,Oceanic Institute |
And 2 more authors.
Aquatic Toxicology | Year: 2012
Selenium (Se) is an essential micronutrient for all vertebrates, however, at environmental relevant levels, it is a potent toxin. In the San Francisco Bay-Delta, white sturgeon, an ancient Chondrostean fish of high ecological and economic value, is at risk to Se exposure. The present study is the first to examine the uptake, distribution, and excretion of various selenocompounds in white sturgeon. A combined technique of stomach intubation, dorsal aorta cannulation, and urinary catheterization was utilized, in this study, to characterize the short-term effects of Se in the forms of sodium-selenate (Selenate), sodium-selenite (Selenite), selenocystine (SeCys), l-selenomethionine (SeMet), Se-methylseleno-l-cysteine (MSeCys), and selenoyeast (SeYeast). An ecologically relevant dose of Se (~500μg/kg body weight) was intubated into groups of 5 juvenile white sturgeon. Blood and urine samples were repeatedly collected over the 48. h post intubation period and fish were sacrificed for Se tissue concentration and distribution at 48. h. The tissue concentration and distribution, blood concentrations, and urinary elimination of Se significantly differ (p≤0.05) among forms. In general, organic selenocompounds maintain higher blood concentrations, with SeMeCys maintaining the highest area under the curve (66.3 ± 8.7 and 9.3 ± 1.0μg. h/ml) and maximum Se concentration in blood (2.3 ± 0.2 and 0.4 ± 0.2μg/ml) in both the protein and non-protein bound fractions, respectively. Selenate, however, did not result in significant increase of Se concentration, compared with the control, in the protein-bound blood fraction. Regardless of source, Se is preferentially distributed into metabolically active tissues, with the SeMet treated fish achieving the highest concentration in most tissues. In contrast, Selenite has very similar blood concentrations and tissue distribution profile to SeCys and SeYeast. From blood and tissue Se concentrations, Selenate is not stored in blood, but taken up rapidly by the liver and white muscle. Urinary elimination of Se is form dependent and peaks between 3 and 12. h post intubation. A basic understanding of the overall Se absorption, distribution, and elimination is provided through monitoring tissue Se concentrations, however, conclusions regarding to the dynamics and the specific processes of Se metabolism can only be inferred, in the absence of kinetic information. © 2011 Elsevier B.V..
Agency: NSF | Branch: Standard Grant | Program: | Phase: BIOLOGICAL OCEANOGRAPHY | Award Amount: 95.30K | Year: 2010
Evidence increasingly demonstrates that selective removal of marine life can induce restructuring of marine food webs. Trophic structure is the central component of mass balance models, widely used tools to evaluate fisheries in an ecosystem context. Food web structure is commonly determined by stomach contents or by bulk tissue stable isotope analyses, both of which are limited in terms of resolution and versatility. The investigators will refine a tool, Amino Acid Compound-Specific Isotopic Analyses (AA-CSIA), which can be broadly applicable for quantifying the time-integrated trophic position (TP) of consumers. Differences in source and trophic nitrogen isotopic composition for specific amino acids will provide an unambiguous and integrated measure of fractional trophic TP across multiple phyla, regardless of an animals physiological condition or of the biogeochemical cycling at the base of the food web. AA-CSIA will allow testing of the efficacy of trophic position estimates derived from ecosystem-based models and promote the evolution of these models into decision-support tools. This project has three goals: 1. To validate the application of AA-CSIA across multiple marine phyla under differing physiological conditions. 2. To compare the application of AA-CSIA across systems with contrasting biogeochemical cycling regimes. 3. To develop the use of AA-CSIA TP estimates for validating trophic models of exploited ecosystems. The investigators will test and refine the approach using a combination of laboratory feeding experiments and field studies across regions with differing biogeochemical cycling regimes. They will determine the applicability of the AA-CSIA approach in a variety of marine organisms assessed in controlled studies. Subsequently, ecosystem components will be sampled from the eastern tropical Pacific, coastal California and the subtropical Pacific gyre. They will also test the effects of sample preservation on the isotopic composition of individual AA to determine whether the approach can be used on archived samples. This tool will allow testing of the efficacy of ecosystem-based models currently used to gain insight into the ecological effects of fisheries removals and improve the reliability of future models required to manage marine resources. In addition to the goal of developing AA-CSIA for use as a TP indicator, the information obtained through this project will provide important species-specific biological data on the feeding behavior of marine organisms that could have implications for their resilience to anthropogenic pressures and climate change.
This project will have direct application to evaluating ecosystem effects of fisheries by providing an unbiased, integrated and independent approach to
estimating trophic structure, and a method by which to validate existing ecosystem-based model outputs and predictions. In addition, the project will have outreach benefits through the involvement of graduate and undergraduate students, and exposure of younger students through K-12 programs. This research will contribute to the greater understanding of the biology of locally important fish species as well as globally important shrimp and endangered marine turtles.
Bushnell M.E.,University of Hawaii at Manoa |
Claisse J.T.,Oceanic Institute |
Laidley C.W.,Oceanic Institute
Journal of Fish Biology | Year: 2010
Reproduction was investigated in relation to lunar and annual cycles in a population of yellow tang Zebrasoma flavescens, a popular aquarium species commercially harvested in Hawaii. Lunar periodicity was determined to be an inherent characteristic of reproduction; peaks in mean daily egg production, female gonado-somatic index (IG) and the fraction of females with eggs were observed at the full moon of each sampled month. An increase in the fraction of late-stage vitellogenic oocytes within the ovaries was also observed at the full moon. Reproductive effort peaked in the late spring and summer as indicated by high values of mean daily egg production, female IG and the recorded incidence of females spawning for at least two consecutive days. Mean daily egg production and IG of monthly samples were lowest in November to February, although some level of egg production continued throughout the year. Large individual variation in batch fecundity was observed, with a range from 44 to > 24 000 eggs per female produced on a single sampling date. Smaller females, 80-120 mm standard length (LS), produced limited numbers of eggs, while females ≥ 120 mm LS were capable of maximal egg production (> 20 000 eggs per batch). In contrast to trends observed in many fish species, no significant relationship between batch fecundity and adult LS > 120 mm was observed in female Z. flavescens. An estimate of annual fecundity (mean ± s.e. 1 055 628 ± 120 596 eggs) was also generated using a simple model of the lunar variability in egg production. This study illustrates the importance of accounting for potential variation in egg production over time, especially with respect to diel and lunar cycles, in the design of reproductive studies of multiple-spawning fishes. Greater insight into the environmental factors that regulate reproductive activity may be gained by determining the relative reproductive investment allocated at each spawning event. The ability to estimate annual fecundity for more multiple-spawning species will facilitate examination of the effects of fishing on the reproductive characteristics of these populations and permit examination of life-history evolution across a broader suite of fishes. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles.
Kline M.D.,Oceanic Institute |
Laidley C.W.,Oceanic Institute
Aquaculture | Year: 2015
The use of copepod nauplii as live prey for first-feeding marine fish larvae is enabling the culture of many marine fish species with small, difficult to rear larvae. The small planktonic nauplii of the copepod Parvocalanus crassirostris is a particularly suitable first-feed due to its small size and ready acceptance by larvae of many species. This study details the relationship between stocking density and egg and nauplii production rates for P. crassirostris copepods, demonstrating a significant decline in culture production as system densities are increased. Fecundity decreased from 26eggsfemale-1day-1 at an adult density of 0.25mL-1 to less than 1eggfemale-1day-1 when operated at 8adultsmL-1. Effects of increasing adult densities on nauplii survival, feed availability, and water quality were sequentially investigated as potential mechanisms for the apparent inverse relationship between adult density and fecundity, with little success. In contrast, increasing egg and nauplii harvest frequency yielded large improvements in egg and nauplii production, with small (1L) scale cultures yielding over 40,000 eggs and nauplii per day when stocked at 4adultsmL-1. A 1500L pilot production system, designed to efficiently remove eggs and nauplii, generated a mean daily output of 18million eggs and nauplii per cubic meter of culture volume under continuous operating conditions for a period of over one month. © 2014 Elsevier B.V.