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White shrimps, Litopenaeus setiferus (Linnaeus, 1767) and pink shrimps, Farfantepenaeus duorarum (Burkenroad, 1939) are two pivotal species in the southern Gulf of Mexico, due to their ecological and economic importance. In this study we present observational evidence of the seasonal and interannual variability of both species in the Términos Lagoon (southern Gulf of Mexico). The results suggest that the hydrography of the water column and the surface circulation exert a strong influence on the density of both species. The results presented here contribute to a better understanding of the dynamics of both species and highlight the need to combine different methodologies to achieve a better interpretation of this system.

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.

White spot syndrome virus (WSSV) is a virulent disease that disrupts shrimp farm operations throughout the world. While the United States has had only limited outbreaks of WSSV within the past several decades, it is important to ensure that this disease does not infect wild penaeid shrimp populations. In Texas, there is a potential for WSSV to spread to wild penaeid populations in the Gulf of Mexico via infected imported nonnative bait shrimp, imported broodstock, or wild crustacean hosts. Due to these potential threats, the Texas Parks and Wildlife Coastal Fisheries Division monitored WSSV in wild brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus from seven major bay systems along the Texas coast during 2019. While no positive samples were detected from the collected shrimp, a power analysis illustrated a potential for low-level WSSV prevalence within Texas shrimp populations that would not be detectable by this monitoring survey. Overall, WSSV does not appear to be a major threat in the Texas region of the Gulf of Mexico, but continual observation and monitoring of wild penaeid shrimp is necessary to protect this resource from future WSSV outbreaks.

Biofloc is a new system, little known or applied in Mexico, that offers a high level of sustainability for aquaculture due to its great versatility in terms of nutrient recycling, which enables savings in feed costs and a significant reduction in water exchange. With the objective of evaluating the results of the use of Biofloc in aquaculture, a simulation of an aquaculture facility using Biofloc culture techniques was conducted under controlled laboratory conditions. The use of a combination of shrimp feed and refined sugar as a carbon source enabled the development of floccules, not only enabling the identification of those high-performing organisms and their development in the medium, but also facilitating shrimp capture in order to evaluate growth during each treatment. The treatments were undertaken in two different culture media, one in brackish water and the other in seawater, in which the length and weight of the animals was measured, with their behavior during the bioassay also recorded. It was found that the brackish medium enabled better shrimp development than the seawater medium, provided that the parameters and material in suspension are kept at stable levels, with the former medium providing shrimp an environment rich in food and free of pathogens.

Litopenaeus setiferus has been described as an economically important native species ranging from the north Atlantic along the coast of the Gulf of Mexico to Florida. Its reproduction has been studied in captivity, as well as some aspects of its nutritional physiology, diseases and adaptation to various environments, including nurseries. In terms of growth, L. setiferus has been compared with L. vannamei for its performance in ponds. As a native species, L. setiferus benefits local fisheries and is also used as a bait shrimp for recreational activity. The present review covers background information and recent advances in research and development efforts to determine its potential both for aquaculture in ponds and intensive biofloc systems (BFT), as well as for the stocking of fishing grounds. The collective research advances for this species presented in this review could help to sustain various strategies, including highly intensive techniques, to rehabilitate L. setiferus in connection with potential institutes.

Coincidental long-term changes in estuarine nekton assemblages and environmental conditions are widely reported. In this study, from a warm-temperate, high salinity, salt marsh-dominated estuary in the southeastern USA, decreases in overall abundance, shifts in species and life stage composition, and changes in seasonal patterns of occurrence coincided with increased water temperature. Biweekly trawl collections in a subtidal creek were made during two 4-year periods separated by more than 30 years. Of the total 111 taxa in the North Inlet estuary, South Carolina, 64% (71) occurred during both the historic (1981–84) and recent (2013–16) periods. The top five species and their proportions of the total annual catches changed between periods. In the recent study period, near-bottom species (Lagodon rhomboides, Bairdiella chrysoura, Litopenaeus setiferus) increased, and pelagic species (Anchoa spp. and Lolliguncula brevis) decreased. The mean abundance of total nekton in the recent period was approximately 50% of historic abundance. Large, but temporary increases in nekton abundance occurred when salinity decreased after major storms. In the recent study period, shifts in the timing of peak abundances from spring to fall, the occurrence of juveniles during winter, and increased diversity suggested responses to significantly warmer winters and summers. Over the 30 year period, the subtidal nekton assemblage transitioned to a state of lower abundance and different composition. Future increases in water temperature, incidences of major storms, and modifications of estuarine habitats due to rising sea level could lead to additional changes in the fauna of warm-temperate estuaries.

Submerged aquatic vegetation (SAV) provides critical habitat for estuarine nekton in the Gulf of Mexico, but habitat quality of SAV beds may change when nonnative species, such as Eurasian watermilfoil (Myriophyllum spicatum), become established. We compared the habitat value of Myriophyllum with another common native SAV (Ruppia maritima) by using field collections to document shifts in nekton community structure and a field experiment to compare growth rates of commercially important juvenile white shrimp (Litopenaeus setiferus). Similar communities were collected from both SAV species, though nekton abundance scaled with SAV biomass. The habitat quality provided by Myriophyllum for white shrimp appeared to meet or exceed that of Ruppia, with densities and growth rates of shrimp in Myriophyllum (2.2 ± 0.47 m−2, 1.0 ± 0.07 mm TL day−1, 25.7 ± 2.98 mg day−1) higher than in Ruppia (1.0 ± 0.36 m−2, 0.6 ± 0.09 mm TL day−1, 11.6 ± 2.04 mg day−1). Though differences were detected between SAV species, other factors, such as hypoxia and interspecific competition, likely contributed to the differences we documented between these habitat types in shrimp densities and growth. Our study provides an example of a nonnative habitat-forming species providing a viable alternative to native habitat. This result contradicts the paradigm of negative effects associated with nonnative species following their introduction into an ecosystem.

Predation is likely the primary source of mortality for juvenile penaeid shrimp and, therefore, a key factor driving their population dynamics. We sampled juvenile penaeids and their potential predators in a salt marsh from July to August 2012 to examine the impact of these predators and possible size-selective predation on the shrimp population. We quantified predator impact using the frequency of occurrence (FO) index and a relative predation index (RPI) that accounts for predator abundance and the number of shrimp consumed per individual predator. Size selectivity was assessed by comparing the size distribution of shrimp in the study area to the size distribution of shrimp removed from predator stomachs. Two penaeid species, white shrimp Litopenaeus setiferus and brown shrimp Farfantepenaeus aztecus, were collected, and most (86%) were juvenile white shrimp ≤ 12 mm carapace length. Spotted seatrout Cynoscion nebulosus, which consumed relatively large shrimp, was the most important predator based on the FO index. Bay whiff Citharichthys spilopterus, which ate the smallest shrimp, was the most important predator based on the RPI. The size distribution of shrimp removed from predator stomachs differed from those collected in the study area; the smallest shrimp were disproportionally more abundant in predator stomachs. Using the RPI, we identified some potentially important predators (e.g., bay whiff) that may impact shrimp populations by consuming the smallest shrimp in estuarine nurseries. Our approach could be useful for examining predator impacts on other populations of juvenile penaeids and more generally for any prey consumed by fish predators.

Severe outbreaks of black gill (BG), heavily melanized gills of crustaceans, have been reported in white (Litopenaeus setiferus) and brown shrimp (Farfantepenaeus aztecus) from coastal Georgia and South Carolina during late summer and fall since the mid-1990s. The cause of this condition is an apostome ciliate that elicits the innate immune response of the shrimp, resulting in the formation of melanized nodules in shrimp gill tissue. In the absence of a definitive identification, the causative ciliate is referred to as the shrimp black gill (sBG) ciliate. During outbreaks, necrosis of gill tissue was often seen in microscopic sections; in some cases, there appeared to be penetration of the ciliate into gill tissue. Shrimp with BG exhibited reduced physical endurance and escape responses compared with shrimp without symptomatic BG. Physical impairment due to BG may contribute to higher predation rates and increased vulnerability to environmental conditions. The infection transmission rate of the sBG ciliate appears to be atypically low for apostome ciliates, raising the question of how epidemic levels of BG reoccur annually. Asymptomatic shrimp placed in direct contact with carcasses (heads) from BG symptomatic shrimp exhibited a significant increase in the development of BG symptoms after 7 days (P = 0.028), but waterborne transmission was not detected. A preliminary survey of sympatric crustacean species, including syntopic species of grass shrimp (Palaemonetes spp.), indicated the possible presence of the sBG ciliate, suggesting that other crustacean species may serve as infection reservoirs. These studies support the conclusion that BG is negatively impacting the penaeid shrimp fishery and highlight the challenges that remain in understanding and managing the ongoing sBG epidemic in the southeastern United States.

Effect of cooking between 1 and 80 min at 60 to 100 °C on several quality attributes of whole peeled shrimp (Litopenaeus setiferus) (80–90 counts/kg) was studied using an isothermal heating method. Cook loss, area shrinkage, and hardness of shrimp increased with increasing heating time and temperature, following a fractional first-order kinetic model with activation energies (E a ) of 71.0, 53.3, and 29.9 kJ/mol, respectively. Cook loss, area shrinkage, and hardness were positively correlated. The toughness of shrimp muscle increased in the initial period of heating, then decreased in the later period during the treatments. The overall color change (ΔE) increased with increasing treatment time and temperature, and followed a zero kinetic model with an E a of 37.2 kJ/mol. The kinetic parameters obtained from this study can be applied toward understanding and predicting shrimp-quality changes during pasteurization treatments, and further provides insight into the pasteurization conditions required to achieve safe and high-quality shrimp products and potentially other crustacean shellfish and seafood products.

Immigration density magnitude and entry sizes of shrimp postlarvae to Terminos Lagoon were analyzed through sixteen fortnightly sampling from March to November in 2013, in three levels in the deepest channel of the Puerto Real inlet. Trapezium nets were used with 1.5 m length, 50 cm mouth diameter and 505 μm mesh, during each sampling 12 casts of 15 minutes/each were made. It was determined the presence of two species Litopenaeus setiferus and Farfantepenaeus duorarum, with total densities of 41.284 and 37.558 Pls 100 m-3 respectively. The annual cycle of immigration of postlarvae was very similar for both species, with a clear pattern of immigration throughout the year, linked to climatic variation, with the highest densities (88%) during rainy season. There were two periods of maximum density, related to the periods of greatest reproduction of these species. The density variation among cast reflects the presence of at least two and probably more postlarvae banks, located some closer than others to the mouth of the lagoon and with different densities in them. The average sizes of the two species were 7.9 mm total length of L. setiferus and 9.0 mm of F. duorarum. The differences in income sizes of both species seem to indicate the habitat preference of adult populations, L. setiferus occurring in more coastal areas than F. duorarum. Considering the variation in density and sizes throughout each sampling period, it is evident that the larvae on the banks belong to different cohorts and that have coincided in their location in front of the mouth.

Penaeid shrimp including Litopenaeus setiferus (white shrimp), Farfantepenaeus aztecus (brown shrimp), and Farfantepenaeus duorarum (pink shrimp) support one of the most valuable commercial fisheries in the U.S. Southeast Atlantic. Since the late 1990s, the fishery, especially in coastal Georgia and South Carolina, has experienced a significant decline. A contributing factor to this decline has been hypothesized to be a severe outbreak of shrimp black gill caused by a ciliate parasite. DNAsequence-based analysis of the gill parasite small subunit rRNA gene identifies the proposed causative agent as being closely related to the apostome ciliate Hyalophysa chattoni; however, morphological characteristics of the ciliate observed by electron microscopy are inconsistent with this identification. Although studies are ongoing to identify this ciliate, it was possible to develop a diagnostic polymerase chain reaction-based assay targeting the small subunit rRNA gene and use it to investigate the seasonal...

The tropically associated black mangrove (Avicennia germinans) is experiencing a climate-induced range shift and expanding into salt marshes of northern Florida, southern Louisiana and most recently, Horn Island, MS. To date, little is known about how black mangroves function as nursery habitat for important fishery species such as shrimps or how their increase may affect survival of such species. The main objective of our study was to determine habitat preference and survival rates of common, economically important penaeid shrimps in the presence and absence of the increasingly abundant tropical predator, the gray snapper (Lutjanus griseus). We also examined the effects of habitat identity and structure on juvenile white shrimp (Litopenaeus setiferus) and brown shrimp (Farfantepenaeus aztecus) behavior, using preference experiments in indoor mesocosms both with and without the predatory gray snapper. Results showed that shrimp prefer Spartina over Avicennia with or without predation risk. Surviv...

Connectivity among estuarine habitats can influence nekton vital rates, and studying these processes requires the ability to track individuals effectively. Passive integrated transponder (PIT) tags have been used to evaluate movement of juvenile fishes in estuaries, yet this technique remains untested for penaeid shrimp . We evaluated survival, growth, and feeding behavior of juvenile white shrimp ( Litopenaeus setiferus ), an ecologically and economically important penaeid species along the US Atlantic and Gulf coasts, implanted with 8-mm PIT tags. Daily survival and tag retention observations and weekly length and weight measurements were made of tagged individuals (n = 18) kept in individual seawater tanks for 28 days, and compared with similarly housed untagged (control) individuals (n = 18). After four weeks, tagged and control shrimp were offered varying densities of a common estuarine prey item, grass shrimp ( Palaemonetes spp.), in feeding trials. Tagged white shrimp exhibited 100% tag retention and an estimated probability of survival after 28 d that was not significantly different from control shrimp (0.81 and 0.94, respectively). We found no evidence of a relationship between tagging treatment or initial shrimp size on the probability of survival. Tagged shrimp demonstrated growth at rates that were not significantly different from control shrimp, and tagged and control shrimp exhibited nearly identical feeding rates on grass shrimp (Palaemonetes spp.) prey. Our results suggest PIT tag technology represents an effective tool to study the movement and vital rates of juvenile white shrimp during their estuarine residence.

Laboratory experiments were conducted under simulated daytime conditions to examine the effects of salinity, sediment texture, size, density, and hunger on burrowing behavior of juvenile brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus . Over all experimental conditions (20,929 observations of 2411 individual shrimp), 77.5% of brown shrimp and 21.4% of white shrimp were observed burrowed with more than half of their body beneath the substrate. The tendency of burrowed shrimp to emerge from burrows when disturbed also was tested. When burrowing rates were examined in combination with this tendency to emerge upon disturbance, only 46.7% of brown shrimp would be susceptible to capture in towed nets, while almost all (97%) white shrimp would be susceptible. All environmental factors examined in this study, except salinity for white shrimp, significantly affected burrowing of these species. When these environmental effects on burrowing were combined with the likelihood of emergence, however, the effects of salinity and substrate type on brown shrimp behavior appeared most likely to affect capture by towed nets. Estuarine abundance indices from resource surveys using towed nets could be adjusted using such vulnerability estimates.

Modeling the distribution and habitat capacities of key estuarine species can be used to identify hot spots, areas where species density is significantly higher than surrounding areas. This approach would be useful for establishing a baseline for evaluating future environmental scenarios across a landscape. We developed species distribution models for early juvenile life stages of brown shrimp (Farfantepenaeus aztecus), white shrimp (Litopenaeus setiferus), blue crab (Callinectes sapidus), and spotted seatrout (Cynoscion nebulosus) in order to delineate the current coastal hot spots that provide the highest quality habitat conditions for these estuarine-dependent species in Louisiana. Response curves were developed from existing long-term fisheries-independent monitoring data to identify habitat suitability for fragmented marsh landscapes. Response curves were then integrated with spatially explicit input data to generate species distribution models for the coastal region of Louisiana. Using spatial autocorrelation metrics, we detected clusters of suitable habitat across the Louisiana coast, but only 1% of the areas were identified as true hot spots with the highest habitat quality for nekton. The regions identified as hot spots were productive fringing marsh habitats that are considered the most vulnerable to natural and anthropogenic impacts. The species distribution models identify the coastal habitats which currently provide the greatest capacity for key estuarine species and will be used in the Louisiana coastal planning process to evaluate how species distributions may change under various environmental and restoration scenarios.

White shrimp (Litopenaeus setiferus) fisheries-independent and fisheries-dependent landings can be highly variable and may be related to environmental factors that influence growth, mortality, and survival. We used linear regression analysis to look for potential relationships between environmental and white shrimp catch-per-unit-effort (CPUE) data collected from the Ashepoo-Combahee-Edisto (ACE) Basin National Estuarine Research Reserve (NERR) for four critical months in the shrimp life cycle. This analysis used data from white shrimp fisheries-independent CPUE (2002 to 2014) and water quality and meteorological variables for August (juvenile), December (sub-adult), March (adult), and April (spawning adult). The results showed that shrimp CPUE was mainly correlated with water temperature, salinity, and dissolved oxygen concentration collected through the ACE Basin NERR’s System-Wide Monitoring Program (SWMP), but offshore wind, precipitation, and intra-annual CPUEs also partially explained the variability in monthly CPUEs. Black gill prevalence was correlated with water temperature and salinity. Additionally, our analysis found that winter water temperatures of ≤11 °C were correlated with reduced shrimp abundance the following spring. Ultimately, managers would like to successfully predict white shrimp stock abundance throughout fishing seasons based on environmental conditions. This study is a first step in identifying the environmental variables that may be useful in predicting white shrimp CPUE in the South Atlantic Bight. The techniques employed here can serve as a basis for predicting and managing other wild annual fisheries stocks.

Cedar Bayou, a natural tidal inlet, was recently dredged to allow for direct water exchange between the Gulf of Mexico and Mesquite Bay, TX, USA. We quantified changes in densities of juvenile nekton (fish, shrimps, and crabs) and community structure in Mesquite Bay after Cedar Bayou was reopened by collecting samples at both control and impact sites using an epibenthic sled 1 year before (October 2013–April 2014) and after (October 2014–April 2015) opening. Significantly higher densities of total nekton were observed at the impact sites after opening using a before-after control-impact design. Red Drum (Sciaenops ocellatus), Atlantic Croaker (Micropogonias undulatus), post-larval penaeid shrimps (Farfantepenaeus aztecus, F. duorarum, and Litopenaeus setiferus), and Blue Crabs (Callinectes sapidus) were significantly more abundant at impact sites after Cedar Bayou was opened. Multivariate analysis showed a significant change in impact site communities after opening and was driven by an increased presence of estuarine-dependent species. Overall, this study demonstrates that opening tidal inlets, such as Cedar Bayou, and reconnecting Mesquite Bay to the Gulf of Mexico increased the presence of numerous estuarine-dependent species, many of which were not present or occurred at very low densities prior to reopening. Thus, reestablishing the historical connectivity between a productive estuary and the open Gulf of Mexico via Cedar Bayou should reinstitute natural nekton recruitment processes important to the Aransas, Mesquite, and San Antonio Bay regions.

In the United States shrimps is the most popular seafood. Penaeidae shrimp species are known to share morphology characteristic and identification based on morphological appearance becomes more challenging when shrimp is processed into ready-to-eat products. Misrepresentation of shrimp is common in commercially available shrimp. The objective of the study was to develop a high-resolution melting (HRM) real time PCR assay targeting the 16S rRNA gene fragment for specific identification of top five penaeid species, Litopenaeus vannamei, Penaeus duorarum, Penaeus monodon, Litopenaeus setiferus and Pleoticus muelleri. The applicability of assay was evaluated using two DNA extraction kits and two real-time PCR master mixes. The HRM assay was evaluated using 43 shrimp samples and results were validated by sequencing shrimp 16S rRNA gene fragment. Assay standardized in this study formed distinct melt curve profile for each species in the normalized and differential melt curve plots. The assay using Apex qPCR 2 × GREEN master mix showed 100% sensitivity and specificity. Further, species identification results obtained by HRM assay was in complete agreement with identification achieved by 16S rRNA gene sequencing. The HRM assay developed in this study can be used as rapid, low-cost, and reliable method for the identification of abovementioned shrimp species.

Knowledge of the environmental factors that influence the spatial–temporal densities of penaeid shrimp in Mecoacan Lagoon is important for understanding their relationship with the presence (migration) and estuarine habitat preferences. In the present study, the relationships between the physical–chemicalcomponents of water and sediments and the population dynamics of penaeid shrimp in Mecoacan Lagoon were evaluated according to a spatial–temporal and multihabitat approach. In six monitoring sites (Boca, Cerros, Mojarrero, Aspoquero Arrastradero and Pajaral), the density and biomass of shrimp were determined from November 2014 to October 2015 based on monthly captures with two nets (seine and renfro) in three habitats: mangrove, soft substrates without vegetation, and submerged aquatic vegetation that corresponds to seagrasses (seagrasses was registered only in Boca and Cerros). The maximum salinity was found in Boca (23 ± 2.6PSU), with pH values ranging from 7.9 ± 0.1 to 8.3 ± 0.2, and the maximum dissolved oxygen was found in Cerros (6.6 ± 0.5mg/L). The average texture of sediments was 62 ± 3.5% sand, 24 ± 2.4% silt, and 14 ± 1.2% clay. The highest organic matter (7.8 ± 1.2%) and nitrogen (875mg/kg) contents were recorded in Pajaral. A total of 5,085 penaeid shrimp were captured (seine 77% and renfro 33%), including the species Farfantepenaeus aztecus (Ives) (1,774 ind.), Farfantepenaeus duorarum (Burkenroad) (1,559 ind.), and Litopenaeus setiferus (L.) (1,752 ind.), with a total wet weight of 2,419 g. The spatial segregation patterns of penaeid shrimp suggest that their temporal distribution and habitat preferences are important for reducing interspecific competition. Salinity, dissolved oxygen, organic matter content, and sediment type were the factors that most influenced the spatial–temporal differences in the density and biomass of the penaeid shrimp among sites. Knowledge of the habitat distribution and preferences of key estuarine species such as penaeid shrimp can be used as an informational baseline for evaluating future environmental scenarios and modeling species distribution along the estuarine gradient.

Changes in freshwater inflow and salinity patterns may affect the nursery value of estuarine systems for penaeid shrimp, but the relationship between salinity and shrimp abundance is complex and likely confounded by other environmental variables. Laboratory experiments can provide insights into salinity selection, and we designed an experimental gradient tank to examine salinity preferences of juvenile brown shrimp and white shrimp. Our design uses gently flowing water to eliminate various physical constraints often associated with selection experiments. We conducted experiments with juvenile brown shrimp (12 trials) and white shrimp (seven trials), to examine selection for salinities along a gradient from 1 to 42. Data were analyzed using contingency tables and log-linear modeling to examine relationships with salinity and possible interactions with temperature. Both brown shrimp and white shrimp were present in all salinities examined within the experimental range. In general, brown shrimp showed a preference for salinities from 17 to 35 and demonstrated avoidance for the extreme low salinities along the gradient. Results for white shrimp were not statistically significant, and this species did not appear to avoid low salinities. There was no effect of water temperature on the observed selection patterns for brown or white shrimp. Our results suggest that although salinity preferences likely exist for these species, strong distribution trends associated with salinity gradients in estuaries are likely caused by other environmental factors.

Properties of hemocyanins vary greatly among crustaceans due to environmental conditions, lifestyle, and genetic variation. These properties can also be modified to maintain aerobic respiration in response to ambient hypoxia, as experienced by both aquacultured and wild populations of penaeid shrimp. Under normoxic conditions, hemocyanin concentrations were significantly higher (P < 0.001) in aquacultured Pacific whiteleg shrimp, Litopenaeus vannamei (10.3 g/100 ml ± 0.23 SEM, n = 49), compared to those in individuals of wild-caught L. vannamei (7.0 g/100 ml ± 0.52 SEM, n = 10), wild Farfantepenaeus aztecus (7.10 g/100 ml ± 0.48 SEM, n = 28), and wild Litopenaeus setiferus (8.0 g/100 ml ± 0.22 SEM, n = 37). Oxygen affinity of hemocyanin at 25 °C in both populations of L. vannamei was higher (Kruskal-Wallis ANOVA on ranks, P < 0.001) (aquacultured P50 = 1.47 kPa ± 0.03 SEM; wild P50 = 1.72 kPa ± 0.01 SEM at pH 7.4) than that of both Atlantic species (F. aztecus P50 = 3.94 kPa ± 0.06 SEM, L. setiferus P50 = 3.98 kPa ± 0.04 SEM at pH 7.4). The effect of l-lactate on oxygen affinity was similar among all wild groups, but significantly smaller in the aquacultured L. vannamei. Total hemocyanin concentration and oxygen binding properties were measured after exposure to 12 days and 25-31 days of hypoxia (30% air saturation). Aquacultured L. vannamei showed no change in hemocyanin concentration for up to 31 days, but both wild F. aztecus and wild L. setiferus displayed a significant increase over the same time period. No discernible change in oxygen affinity of hemocyanin was detected in any of the three species. Hypoxia tolerance appears to differ among these species of penaeid shrimp, due to either an inherent difference among the species, domestication by aquaculture, or a combination of both.

White spot syndrome virus (WSSV) is a virulent pathogen of cultured shrimp and was first detected in farms in South Carolina (USA) in 1997 and subsequently in wild shrimp in 1999. We screened groups of 1808 wild Atlantic white shrimp Litopenaeus setiferus and 300 blue crabs Callinectes sapidus collected from South Carolina, Georgia, and Florida for the presence of WSSV using the Shrimple ® immunoassay-strip test, with all positives and random subsets of negatives tested by TaqMan real-time PCR and in infectivity bioassays. Of 87 shrimp and 11 crabs that tested positive using the Shrimple ® test, only a single C. sapidus was confirmed to be infected with WSSV by PCR and the infectivity bioassay. The data indicate that the prevalence of WSSV in these species is low in these southeastern US regions, but that C. sapidus may serve as a biological reservoir.

The effects of droughts on benthic infaunal communities and three epifaunal species were determined in three semi-arid central Texas estuaries with different inflow dynamics and consequent salinity regimes: the Nueces, Lavaca-Colorado, and Guadalupe Estuaries. Periods (months or years) were considered to be in drought if mean salinities were in the upper quartile of historic salinities. This drought classification method was verified by comparing the Palmer Drought Severity Index of the catchments with the drought classifications within each estuary. Droughts have demonstrable effects on estuary water column condition, notably decreases in turbidity, nutrient concentrations, and chlorophyll concentrations. Droughts do not appear to be important drivers of infaunal communities in estuarine regions with normally high salinities (25–32) although they coincide with increased diversity and changes in community composition in estuarine regions that have lower salinities (10–19). Droughts cause decreases in Litopenaeus setiferus (white shrimp) and Callinectes sapidis (blue crab) abundances and spatial extents. This indicates that droughts, especially when combined with water diversions, may negatively affect primary and secondary productions in other semi-arid estuaries of the world.

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.

Processes regulating juvenile growth and mortality of white shrimp Litopenaeus setiferus in coastal nurseries may be particularly important in regulating offshore adult population size and sustainability. To advance the integration of these processes into fishery stock assessments, and to provide a better understanding of the functional role of coastal nurseries for fishery species, we explored the potential effects of variable juvenile growth and survival on white shrimp population growth rate. We developed a population model that incorporates available information on vital rates (growth, mortality, fecundity) for each shrimp life stage. We used the model to explore the potential impacts of variability in juvenile growth and mortality rates on the overall population growth rate. Modest changes in juvenile growth and mortality rates were projected to have a greater impact on stock size than the full range in fishing mortality over the past few decades. These results suggest that variability in juvenile survival may be a strong driver of adult stock size and that the processes that regulate juvenile growth and mortality need to be properly understood for the effective management of coastal nurseries and shrimp stocks.

Parasites that invade the nervous system of their hosts have perhaps the best potential to manipulate their host’s behavior, but how they manipulate the host, if they do at all, could depend on their position within the host’s nervous system. We hypothesize that parasites that live in the nervous system of their host will be randomly distributed if they exert their influence through non-specific effects (i.e., general pathology), but that their position in the nervous system will be non-random if they exert their influence by targeting specific neural circuits. We recorded the position of larval tapeworms, Polypocephalus sp., in the abdominal ganglia of white shrimp, Litopenaeus setiferus. Tapeworms are more common within ganglia than in the section of the nerve cord between ganglia, even though the nerve cord has a greater volume than the ganglia. The tapeworms are also more abundant in the periphery of the ganglia. Because most synaptic connections are within the central region of the ganglion, such positioning may represent a trade-off between controlling the nervous system and damaging it.

Gulf of Mexico, white shrimp, Litopenaeus setiferus, catch statistics have been collected by NOAA’s National Marine Fisheries Service for over 50 years. Recent occurrences such as natural and manmade disasters have raised awareness for the need to publish these types of data. Here we report shrimp data collected from 1984 to 2011. These 28 years of catch history are the time series used in the most recent Gulf of Mexico white shrimp stock assessment. Fishing effort for this stock has fluctuated over the period reported, ranging from 54,675 to 162,952 days fished. Catch averaged 55.7 million pounds per year, increasing significantly over the times series. In addition, catch rates have been increasing in recent years, with CPUE levels ranging from 315 lb/day fished in 2002, to 1,175 lb/ day fished in 2008. The high CPUE’s we have measured is one indication that the stock was not in decline during this time period. Consequently, we believe the decline in effort levels is due purely to economic factors. Current stock assessments are now using these baseline data to provide managers with further insights into the Gulf L. setiferus stocks.

Marsh shoreline, an important habitat for juvenile penaeid shrimps, was extensively oiled in coastal Louisiana by the Deepwater Horizon oil spill of 2010. The effect of this spill on growth was examined for brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus held for 7 days in field mesocosms in Barataria Bay during May and August 2011, respectively. The experiments each had 10 treatment combinations, five apparent oil levels, each one with and without added food. Mesocosms were placed in northern Barataria Bay along shorelines that varied in oiling (designated as heavy, moderate, light, very light, or none based on NOAA surveys), and shrimp in half the mesocosms received additional food. Polycyclic aromatic hydrocarbon (PAH) concentrations determined from sediment cores collected at each mesocosm were significantly higher at heavy and moderate than very light shorelines and also higher at moderate than light and none shorelines. Brown shrimp grew more slowly at heavy than very light or none shorelines, and a statistically significant negative relationship was detected between brown shrimp growth rates and sediment PAH concentrations. In August, PAH sediment concentrations had decreased significantly from the values measured in May, no significant difference in white shrimp growth rates was detected among oiling levels, and no relationship was detected between white shrimp growth and sediment PAH concentrations. Both brown shrimp and white shrimp grew more rapidly in mesocosms where food was added. Our study shows that exposure to nonlethal concentrations of petroleum hydrocarbons can reduce growth rates of juvenile penaeid shrimps.

Vegetated salt marsh habitats are widely considered critical for supporting many species of nekton, yet direct evidence of the processes controlling marsh habitat use for most species remains elusive. We related salt marsh flooding patterns and nekton trophic dynamics among 14 sites spanning 2500 km across the northern Gulf of Mexico (GoM) and southern Atlantic coasts of the USA. Functional access for nekton to marsh vegetation (edge flooded to ≥5 cm depth) ranged from 90% access in the western GoM and Pamlico Sound. Food web mixing models based on stable isotope analysis show that the impor- tance of Spartina trophic support for common nekton may be regulated by the duration of marsh surface flooding. In particular, the potential contribution of Spartina production was positively related to indices of marsh surface flooding for brown shrimp Farfantepenaeus aztecus, white shrimp Litopenaeus setiferus, small (≤60 mm carapace width) blue crabs Callinectes sapidus, grass shrimp Palaemonetes pugio, and killifish Fundulus heteroclitus/grandis. The value of Spartina salt marsh production to several common species of nekton appears to depend, at least in part, on direct access to the vegetated marsh surface, which is regulated by hydrodynamics. Hence, the substantial geographic and temporal variability in marsh flooding regulates the func- tional roles and value of these tidal wetlands for aquatic organisms.

A series of experiments were conducted to examine the effects of salinity (1‐48g/L) on the biological performance, as evaluated by growth and survival, of the Pacific white shrimp, Litopenaeus vannamei, and the Atlantic white shrimp, Litopenaeus setiferus, reared at temperatures of 20, 24 or 28C. Poor growth and survival of L. vannamei was observed after 21‐28d of culture at low salinity (2 and 4g/L) at 20C. Raising salinity to 8 and up to 32g/L significantly increased survival at this temperature, indicating that avoiding low temperatures is critical for survival of this species when reared at low salinity. A major improvement in the growth rate of L. vannamei was observed at 24C, but it still was sub-optimal compared to growth observed at 28C. Irrespective of salinity, high survival rates were observed at both 24 and 28C, but variable growth rates were recorded. Contrary to L. vannamei, the Atlantic white shrimp, L. setiferus, which was reared for 28d at 24C only, had better growth performance at 8g/L compared to 2, 16 and 32g/L. Under equal experimental conditions, L. setiferus had considerably lower weight gain and survival than L. vannamei.

Selective tidal-stream transport is commonly used by marine animals to migrate between oceanic and estuarine habitats as they undergo ontogenetic migrations, but behaviors used to accomplish these migrations may differ among species, life history stages, or locations. The ecologically and commercially important brown shrimp, Farfantepenaeus aztecus, pink shrimp, Farfantepenaeus duorarum, and white shrimp, Litopenaeus setiferus, undergo ontogenetic migrations between spawning locations on the continental shelf and juvenile nursery habitats in estuaries. This study evaluated the role of endogenous rhythms in vertical swimming activity in Flood Tide Transport (FTT) of postlarvae entering estuaries and the potential for shifts in behavior between the postlarval and juvenile stages. Brown and pink shrimp postlarvae exhibited circatidal rhythms in vertical swimming activity with period lengths of approximately 12.4 h that coincided with the time of early flood tide in the field, whereas white shrimp postlarvae did not exhibit an endogenous rhythm in swimming activity. Pink shrimp juveniles (20-40 mm total length) exhibited a distinct circadian activity rhythm with a mean period length of 23.8 ± 3.7 h and peak swimming during the time of night in the field. Juvenile brown and white shrimp exhibited relatively weak circatidal activity rhythms with peak vertical swimming around the times of ebb and early flood tide in the field, respectively. These results suggest that 1) brown and pink shrimp postlarvae exhibited endogenous activity rhythms that would enhance FTT, 2) white shrimp postlarvae likely depend on environmental cues associated with flood tide to accomplish FTT, and 3) pink shrimp are unique among these three species in exhibiting a shift from a circatidal to a nocturnal swimming activity rhythm between postlarval and juvenile stages.

This study presents an Ex-Post Facto analysis of diseases of wild juvenile and adults of Litopenaeus setiferus collected from a field survey at the Natural Protected Area of Terminos lagoon, southern Mexico. The objective of the present approach was to determine if sampling site and/or shrimp age were contributing risk factors for disease between juvenile and adult shrimp; if there was a determined period of time in a year cycle when diseases were more critical, and if the analysis would help to decision- making considering what population would pose less risk of disease-carrying when withdrawn for experimental purposes; all under an after-the-fact (ex-post facto) approach. We identified that juvenile shrimp were at more risk of contracting some diseases in the estuarine environment and June, July and August months, were found to be a critical period when colonizing and parasitic diseases maintained a significant high prevalence in the shrimp population. These assumptions may help for decision-making when wild shrimp have to be withdrawn from their natural environment for research purposes.

A new member of antimicrobial peptide genes of the penaeidin family, penaeidin 3, was cloned from the haemocytes of Indian white shrimp Fenneropeneaus indicus ( F. indicus ), by reverse transcription PCR (RT-PCR) and rapid amplification of cDNA end (RACE-PCR) methods. The complete nucleotide sequence of cDNA clone of Indian white shrimp F. indicus Penaeidin 3 (Fi-Pen3) was 243 bp long and has an open reading frame which encodes 80 amino acid peptide. The homology analysis of Fi-Pen3 sequence with other Penaeidins 3 shows higher similarity with Penaeus monodon (92%). The theoretical 3D structure generated through ab initio modelling indicated the presence of two-disulphide bridges in the alpha-helix. The signal peptide sequence of Fi-Pen3 is almost entirely homologous to that of other Penaeidin 3 of crustaceans, while differing relatively in the N-terminal domain of the mature peptide. The mature peptide has a predicted molecular weight of 84.9 kDa, and a theoretical pI of 9.38. Phylogenetic analysis of Fi-Pen3 shows high resemblance with other Pen-3 from P. monodon , Litopenaeus stylirostris , Litopenaeus vannamei and Litopenaeus setiferus . Fi-Pen3 found to be expressed in haemocytes, heart, hepatopancreas, muscles, gills, intestine, and eyestalk with higher expression in haemocytes. Microbial challenge resulted in mRNA up-regulation, up to 6 h post injection of Vibrio parahemolyticus . The Fi-Pen3 mRNA expression of F. indicus in the premolt stage (D 01 and D 02 ) was significantly up-regulated than the postmolt (A and B) and intermolt stages (C). The findings of the present paper underline the involvement of Fi-Pen3 in innate immune system of F. indicus.

The Laguna Madre of Mexico is the second biggest hypersaline coastal lagoon from the Gulf of Mexico, and supports the most important artisanal shrimp fishery in the country. The population size structure of penaeids from this artisanal fishery was examined, analyzing temporal and interspecific variations. The results indicate that the shrimp fishery in Laguna Madre is supported by three penaeid species (Farfantepenaeus aztecus, F. duorarum, and Litopenaeus setiferus); the consistent presence of F. aztecus and F. duorarum caught throughout the year contrasted with the scarce occurrence of L. setiferus, which exhibited significant fluctuations in its relative contribution to shrimp catches. Significant differences in monthly mean size were observed for the three species. Larger individuals were caught in colder months (November–March); however, the body condition of shrimp was higher in warmer months (April–October). A negative relationship between shrimp size and water temperature was found, which...

Few studies have compared oyster habitat use with adjacent vegetated and non-vegetated habitats. We investigated habitat use by six common, estuarine, invertebrate species. In order to better understand the species-specific use of oyster and adjacent habitats within the salt marshes of Grand Bay NERR, MS, we examined the abundance patterns and size distributions among oyster, vegetated marsh edge (VME), and non-vegetated bottom (NVB) for three seasons (Fall 2003, Spring 2004, Summer 2004) for the following species: blue crab Callinectes sapidus, brown shrimp Farfantopenaeus aztecus, white shrimp Litopenaeus setiferus, daggerblade grass shrimp Palaemonetes pugio, flatback mud crab Eurypanopeus depressus, and oystershell mud crab Panopeus simpsoni. Three main trends emerged concerning habitat use: 1) the three crab species (juvenile C. sapidus, E. depressus, P. simpsoni) occupied oyster and VME habitats in higher abundances relative to NVB with minor to moderate fluctuations in seasonal abundance. ...

Larval tapeworms (Polypocephalus sp.) reside within the central nervous system of decapod crustaceans. Living within the nervous system would seem to create an excellent opportunity for the parasites to manipulate the behavior of their hosts, so we tested the hypothesis that behavior of white shrimp ( Litopenaeus setiferus ) would be correlated with the level of parasitic infection. We videorecorded the behavior of L. setiferus for 8 hr, then examined the nervous system and digestive glands for parasite infection. Larval Polypocephalus sp. were found in the nerve cord, often in large numbers, but only very rarely in the digestive gland, which was typically infected by the larval stage of the nematode, Hysterothylacium sp. There were significantly more Polypocephalus larvae in the abdominal and thoracic ganglia than the subesophageal ganglia and brain. Walking, but not swimming, was significantly and positively related to the number of Polypocephalus sp. lodged in nervous tissue, as well as shrimp carapace length. Polypocephalus sp. is 1 of only a few parasites residing inside the host nervous system and it may, therefore, be suitable for investigating mechanisms of parasite manipulation of invertebrate host behavior.

We surveyed protozoan and metazoan parasites as well as white spot syndrome virus (WSSV) and infectious hypodermal hematopoietic necrosis virus (IHHNV) in white shrimp Litopenaeus setiferus and the palaemonid prawn Macrobrachium acanthurus native to the lower Jamapa River region of Veracruz, Mexico. The presence of parasites and the infection parameters were evaluated in 113 palaemonid prawns collected during the northwind (n = 45), rainy (n = 38) and dry seasons (n = 30) between October 2007 and July 2008, and in 91 shrimp collected in the rainy season between May and June 2008. In L. setiferus, ciliates of the subclass Apostomatia (Ascophrys sp.) were evident in gills, and third-stage larvae of the nematode Physocephalus sexalatus were evident in the stomach. Cestodes of the genus Prochristianella were evident in the hepatopancreas, while some gregarines of the genus Nematopsis, as well as unidentified larval cestodes, were observed in the intestine. Histology identified Ascophrys sp. in association with gill necrosis and tissue melanization. Slight inflammation was observed in intestinal epithelium near cestode larvae. In M. acanthurus, epibionts of the protozoans Epistylis sp., Acineta sp. and Lagenophrys sp. were observed under uropods, periopods and pleopods. An unidentified ciliate of the Apostomatia was also found in the gills, and Nematopsis was identified in the intestine. No histopathology was observed in association with these parasites. Moreover, neither WSSV nor IHHNV were detected by the polymerase chain reaction (PCR) in any of the L. setiferus or M. acanthurus analysed.

I reviewed the penaeid literature for characters ‘traditionally’ used to discriminate Litopenaeus setiferus, Farfantepenaeus aztecus, and F. duorarum and examined early life stages (ELS) with 3 + 0 to 8 + 2 rostral teeth based on these characters. The species identity of most of the specimens examined were verified ‘a priori’ with a multiplex PCR assay that targeted the 16S rRNA mitochondrial gene. My objectives were to re-evaluate ‘traditional’ characters by re-examining ELS for differences in morphology and timing of character development based on number of rostral teeth rather than body size, and, to identify a reliable suite(s) of characters to discriminate taxa in areas where distributions overlap. I found the absence of spinules along the dorsal carina of the sixth pleomere in young with < 4 dorsal teeth (DT), and the supposed difference in length of the third pereopod relative to the distal margin of the eye to be unreliable characters for generic discrimination. Differences in the thoraci...

Freshwater inflows from river diversions may affect nekton populations by altering the salinity and temperature of estuarine waters. To investigate the influence of these environmental variables on the growth and survival rates of brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus, we conducted field experiments in May and September 2007 to expose experimental animals to the range of different combinations of salinity and water temperature that commonly occur in an estuarine environment. Growth rates for shrimp held in mesocosms for approximately 7 days were compared among four locations and three treatments; locations were identified by the dominant marsh vegetation and distance from the Gulf of Mexico (low to high salinity: Intermediate, Brackish, Saline UE = Saline Up Estuary, Saline DE = Saline Down Estuary). At each location, the treatments were replicated four times and included shallow water with additional food, shallow water without food added, and deeper water (an attempt to expose animals to lower temperatures). Our experiments were designed to test the null hypothesis that shrimp growth and survival rates did not differ by location or treatment. Both brown shrimp and white shrimp grew more slowly at the Intermediate than higher salinity locations. Potential prey (benthic infauna) biomass was relatively low at both the Intermediate and Brackish locations in May, and both shrimp species consistently grew faster in mesocosms where food was added. We conclude that reduced growth in low salinity environments is likely due to the combined effects of increased metabolic costs and less food in these areas. River diversions that reduce estuarine salinities over a large portion of available habitat during peak recruitment periods may reduce overall growth rates and shrimp productivity in the affected areas.

Shrimp byproducts are an excellent source of astaxanthin. The antioxidant-rich natural astaxanthin, dispersed in alpha-linolenic acid-rich flaxseed oil, may provide healthier functional food options for consumers. The goal was to develop astaxanthin dry powder using microencapsulation technology. Emulsions prepared with flaxseed oil (EF) and flaxseed oil containing shrimp astaxanthin (ESA) were spray-dried to produce microencapsulated powders using a pilot scale spray dryer. Energy required for spray drying EF and ESA and physicochemical properties of the powders were evaluated. The energy required to spray dry EF and ESA was 2.676 × 104 and 2.405 × 104 kJ kg−1 respectively. The measured production rate of microencapsulated flaxseed oil (MF) and flaxseed oil containing shrimp astaxanthin (MSA) was lower than the estimated production rate. The astaxanthin concentration of MSA was 16.08 μg g−1 powder. The lipid oxidation of MSA was lower than that of MF at 5, 25, and 40 °C during 26 days storage. Degradation of astaxanthin in MSA, fitted with first-order reaction kinetics model, showed that the degradation rate constant for MSA increased with increased storage temperature, which indicated that astaxanthin degraded faster at higher temperature than that at lower temperature. This study demonstrated that astaxanthin extracted from shrimp byproducts using flaxseed oil can be microencapsulated using spray drying technology.

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.

This study describes a multiplex PCR assay based on the 16S rRNA mitochondrial gene to identify the penaeid shrimp Farfantepenaeus aztecus, Farfantepenaeus duorarum, Farfantepenaeus brasiliensis and Litopenaeus setiferus, all native to the Gulf of Mexico, and the exotic Litopenaeus vannamei. The assay was validated using positively identified adult shrimp and confirmed by direct sequencing. Samples of postlarvae and early juveniles collected in the eastern and western Gulf of Mexico were tested yielding 119 F. aztecus, 78 F. duorarum and five L. setiferus. Reliable identification of the morphologically similar early life stages of F. aztecus and F. duorarum has important implications for management and conservation. Similarly, the ability to identify L. vannamei is relevant as early detection could help minimize the ecological impact if this species escapes to the wild.

We evaluated two marsh terracing restoration projects (GI=Galveston Island State Park, PM=Pierce Marsh) to compare nekton density and biomass between locations and among habitat types (open water pre-construction, open water post-construction, terrace marsh, terrace pond). Most (72%) animals collected were decapod crustaceans. Few differences in nekton abundance were observed over time (pre-construction versus post-construction open water). Comparisons of pre-construction to post-construction open water showed that the locations differed environmentally (e.g., turbidity) and in populations of nekton species. Density and biomass of gulf menhaden Brevoortia patronus and spot Leiostomus xanthurus in spring and density of white shrimp Litopenaeus setiferus in fall were higher at PM than GI, whereas densities and biomass of blue crab Callinectes sapidus, density of pink shrimp Farfantepenaeus duorarum, and biomass of brown shrimp Farfantepenaeus aztecus in the fall were higher at GI than PM. Despite location differences, constructing terraces appeared to benefit fishery species at both locations. Densities of brown shrimp, blue crab, white shrimp (fall), and pink shrimp (fall) and the biomass of brown shrimp, blue crab, and white shrimp (fall) were higher in terrace marsh than open water. Marsh terracing appears to be an effective tool for enhancing fishery habitat in degraded coastal systems.

We conducted field growth experiments to evaluate marsh-terracing restoration in Galveston Bay, Texas (USA). Growth rates were compared for selected species held in mesocosms for ~7 d within 4 habitat type treatments: terrace marsh edge (TerM), terrace pond (TerP), reference marsh edge (RefM), and reference pond (RefP). Environmental variables were measured during each experiment, and values measured inside the experimental mesocosms generally tracked outside values. Mean daily growth rates were 0.7 to 1.9 mm (30 to 143 mg) for brown shrimp Farfantepenaeus aztecus, 0.4 to 1.2 mm (8 to 67 mg) for white shrimp Litopenaeus setiferus, 0.3 to 0.6 mm (15 to 194 mg) for blue crab Callinectes sapidus, and 0.1 to 0.4 mm (0.3 to 3 mg) for daggerblade grass shrimp Palaemonetes pugio. No difference was detected in growth rates among treatments for blue crab and daggerblade grass shrimp. White shrimp growth rates in August 2002 were higher in TerP than RefP, and in October 2002, were higher in RefP than TerM. Brown shrimp grew more rapidly in RefM than TerM in early May 2003, but mean growth rates were similar in both habitat types later in May 2003, and significantly lower than growth rates in RefP and TerP. Even though growth rates were not consistently higher in terrace habitat types, production rates may be higher in terrace fields than over shallow non-vegetated bottom (the habitat type replaced by marsh terracing); much higher densities of fishery species in terrace habitats more than compensate for occasionally lower growth rates there. However, our production rates should be used cautiously, because we did not include mortality rates in these estimates. We recommend using a combination of different metrics, including mortality rate, to assess secondary productivity of marsh terracing or other restoration projects.

The overall purpose of this study was to develop a quantitative model to assess the influence of L. setiferus predation on subtidal macrobenthic abundance cycles in an estuarine creek system. Subtidal macrobenthic populations in temperate marine soft-bottom environments are known to undergo seasonal abundance cycles. Although the factors responsible for driving these seasonal shifts in abundance are difficult to identify, both environmental and biological factors have received credit. Juvenile white shrimp (Litopenaeus setiferus) are seasonally abundant epibenthic predators in the North Inlet estuary that have significant influence upon estuarine macrobenthic densities. Data generated from field and laboratory studies were combined with 20 years of long-term monitoring data to simulate seasonal variations in macrobenthos abundance under different levels of L. setiferus predation. Model simulations generated clear reductions in subtidal macrobenthos densities, confirming the role of L. setiferus as major consumers of macrobenthos. Model uncertainty was small, and model accuracy increased with shrimp density. In years with low or medium shrimp densities, predicted macrobenthos densities tended to be higher than those observed, yet predicted rates of decline still paralleled long-term observations. Model simulations best matched observed data for the representative high shrimp density year tested. Results indicate that variability in multiple factors, including L. setiferus predation, likely control macrobenthos abundance cycles. Predation by earlier-arriving epibenthic feeders may drive initial macrobenthos declines earlier in the year, with L.setiferus predation then intensifying and extending these declines throughout the summer and fall. This modeling approach is an important step toward understanding the role of multiple factors driving seasonal macrobenthos dynamics, and the L.setiferus population was tractable for examining the importance of epibenthic predation on these organisms.