Juvenile White Shrimp Litopenaeus Setiferus Research Articles

The adverse effects of the phenylpyrazole, fipronil, on juvenile white shrimp Litopenaeus setiferus.

Chemical pesticides are commonly used world-wide, and they can flow into estuaries and affect non-targeted organisms. We evaluated the effects of six concentrations of the phenylpyrazole, fipronil (0.0, 0.005, 0.01, 0.1, 1.0, and 3.0 μg/L), which are environmentally relevant, on white shrimp Litopenaeus setiferus (initially averaging 0.80 ± 0.08 g/shrimp). Compared with the control, survivorship of shrimp over 45 days declined significantly at the higher concentration treatments. Growth was affected at all concentrations, and the percent weight gain decreased significantly. Inter-molt intervals were longer in all treatments. Changes in swimming and feeding behavior of shrimp were observed under all treatments, and change in body color was observed at higher concentration treatments. Lipid content in shrimp decreased significantly while ash content increased with fipronil concentration. Fipronil adversely affected white shrimp under the concentrations observed in the environment and monitoring of fipronil use is needed in coastal areas.

Estimating Natural Mortality Rates of Juvenile White Shrimp Litopenaeus setiferus

Comparisons of natural mortality rates can be used to identify essential habitat and nursery areas for fishery species. We estimated and compared natural mortality rates of juvenile white shrimp Litopenaeus setiferus using length-frequency and mark-recapture data and attempted to identify factors that may affect these mortality rates. Daily instantaneous natural mortality rates (95 % confidence interval (CI)) obtained from length-frequency data by following individual cohorts were 0.043 (0.031–0.054) and 0.014 (0.0–0.039). Combining all length-frequency data, converting to age-frequency data, and using two types of catch-curve analyses yielded estimates of 0.069 (0.042–0.095) and 0.060 (0.046–0.073). Mark-recapture estimates obtained in a separate study from two ponds were 0.129 (0.054–0.203) and 0.014 (−0.048–0.076). These estimates are comparable to previously reported values for this species, but we are the first to report a measure of precision with our estimates. In the mark-recapture study, mortality rates appeared to be related to predator abundance in ponds and flooding patterns of the surrounding marsh. The only mortality rate significantly different from any of the other estimates was the lower of the two length-frequency estimates, but this result should be interpreted with caution because of the uncertainty in that estimate, relative imprecision of our estimates, and confounding factors between the methods we used to estimate mortality. Despite this caveat, the results from our study can be used to improve population models for L. setiferus and our understanding of the role of marsh habitats as nursery areas.

Growth and mortality of juvenile white shrimp Litopenaeus setiferus in a marsh pond

Despite the widely held view that certain estuarine habitats are more valuable as nurseries because they provide enhanced growth and reduced mortality, there remain few estimates of growth and mortality rates in support of this paradigm. We conducted field caging experiments and collected weekly nekton samples in shallow open-water habitat in a marsh pond during summer and fall 2007 in Galveston Bay, Texas, USA, to estimate growth and morality rates of juvenile white shrimp Litopenaeus setiferus. Growth rates (mean ± 1 SE) were lower during the summer experiment (0.77 ± 0.05 mm d–1) than the fall (0.91 ± 0.04 mm d–1), and high summer water temperatures may have inhibited shrimp growth. Cohort analysis to derive mortality estimates from 15 weekly sampling trips failed due to extended periods of continuous recruitment, the lack of clearly identifiable cohorts, and high temporal variability in abundance estimates. Catch-curve analysis provided estimates of mean daily instantaneous mortality (Z) during the sampling period of 0.181 for post-larvae and early juveniles 28 mm. The mortality estimates must be interpreted with caution due to potential problems meeting the assumptions of catch-curve analysis. Despite the challenges, comparisons of vital rates among habitats are required to validate long-held paradigms on the functioning of estuarine nurseries and the importance of various coastal habitats in the support of fishery species.

Relative nursery function of oyster, vegetated marsh edge, and nonvegetated bottom habitats for juvenile white shrimp Litopenaeus setiferus

Shallow estuarine habitats, including vegetated marsh edge (VME), oyster reefs (oyster), and nonvegetated soft bottom (NVB), provide important functions for estuarine resident and estuarine-dependent species. A paucity of information exists concerning relative nursery value of these habitats for juvenile fishes and invertebrates. In Grand Bay, MS and Weeks Bay, AL, National Estuarine Research Reserves (NERR), this study evaluated the potential of the three habitats to serve as nurseries by quantifying habitat-specific density, size, growth, and survival of juvenile white shrimp Litopenaeus setiferus. Drop sampling in Oct 2003 and Jul 2004 indicated that white shrimp density was significantly greater in oyster and VME when compared with adjacent NVB. No significant difference occurred in density between oyster and VME. Significantly larger shrimp were collected in NVB, intermediate-sized shrimp were collected in oyster, and smaller shrimp were collected in VME. Using field enclosures to study growth of juvenile white shrimp we found significantly higher growth in oyster when compared with NVB and VME. Predator mesocosm experiments indicated that when blue crabs were used as predators, white shrimp juveniles experienced significantly higher survival rates in VME and NVB when compared with oyster. Our study suggests that juvenile white shrimp may select for oyster over NVB because of higher food availability and not necessarily for refuge needs from predation by blue crabs. In addition, juvenile habitat needs may shift with individual growth, indicating that the relative nursery value of a habitat is not inclusive for all juvenile sizes. Similar to VME, oyster provides an important function in the juvenile stages of white shrimp and should be examined further as a potential nursery habitat.

Abundance and distribution of juvenile white shrimp Litopenaeus setiferus within a tidal marsh landscape

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 232:213-223 (2002) - doi:10.3354/meps232213 Abundance and distribution of juvenile white shrimp Litopenaeus setiferus within a tidal marsh landscape Stacey R. Webb*, R. T. Kneib University of Georgia Marine Institute, Sapelo Island, Georgia 31327, USA *Present address: Florida Department of Environmental Protection, 2600 Blair Stone Road, M.S. 3555, Tallahassee, Florida 32309, USA. E-mail: stacey.webb@dep.state.fl.us ABSTRACT: We measured variation in low-tide abundance of juvenile white shrimp Litopenaeus setiferus in subtidal creek channels relative to the amount of intertidal drainage area and creek edge in an adjacent tidal marsh. Samples were collected over a 2 yr period (1998 and 1999) and included 201384 individual shrimp taken by cast net during July to November from 4 different tidal creek sub-systems in the Sapelo Island National Estuarine Research Reserve on the coast of Georgia (USA). Total drainage areas of the sub-systems ranged from 0.59 to 1.19 km2. Variation in intertidal and subtidal areas, and creek edge (interface between the vegetated marsh and open water) within the upper, middle and lower reaches of each sub-system was measured from high-resolution scaled (1:16 000) aerial photographs. Shrimp were most abundant and smaller in the upper reaches of tidal channels, where the adjacent intertidal drainage area and vegetated marsh edge were greatest. Regression analysis of shrimp abundance, measured as mean catch per unit effort, showed a strong positive relationship (p < 0.001; R2 = 0.86) with the amount of intertidal marsh edge in associated reaches (upper, middle or lower) of the creek sub-systems. Distribution and abundance of shrimp within tidal creeks probably reflected a link between estuarine landscape structure and accessibility of resources in the vegetated marshes that support shrimp production. Among the implications for management of shrimp resources in marsh habitats, we recommend a precautionary approach in making land-use decisions that would reduce structural complexity of marsh landscapes, particularly in the upper reaches of tidal creeks where juvenile white shrimp are concentrated and complex networks of creek channels enhance access to intertidal resources within the estuarine nursery. KEY WORDS: crustacean · Edge · Essential fish habitat · Estuarine nursery · Intertidal · Penaeid Shrimp · Sapelo Island Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 232. Online publication date: May 03, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.