Farfantepenaeus Duorarum Research Articles

Potential Implications of Excluding Live‐Bottom Habitat from a Bottom‐Trawl Survey in the Eastern Gulf of Mexico

AbstractData provided by the Southeast Area Monitoring and Assessment Program (SEAMAP) shrimp/groundfish trawl survey have long been used in assessing diverse managed taxa, including several reef fishes; however, there are rising concerns over the impacts of trawling on live‐bottom habitats. Using data collected from summer SEAMAP trawl surveys (2009–2016; N = 1,103), we examined how avoiding areas of live‐bottom habitat might affect the survey's ability to assess interannual changes in abundance of managed reef fish taxa. Trawl samples at 48% of sampling sites contained <50 kg of sponge, and 12% of sampling sites contained at least 50 kg of sponge, while 40% of sites had zero sponge bycatch. Mean number of taxa, taxonomic richness, and taxonomic diversity were significantly higher as sponge bycatch increased, while the total number of individuals remained the same. To examine interannual variability of managed reef fish taxa, annual indices of relative abundance were calculated on different subsets of data (all data, data excluding sites with sponge bycatch ≥50 kg, and data excluding all sites with sponge bycatch). For Red Snapper Lutjanus campechanus and pink shrimp Farfantepenaeus duorarum, indices and general trends were largely unaffected by excluding sites with sponge, but for most selected taxa (e.g., Gray Triggerfish Balistes capriscus and Red Grouper Epinephelus morio), overall trends were affected by excluding sites that contained sponge bycatch, and in some cases the frequency of occurrence did not meet the requirement to calculate an index of abundance (i.e., <5%) when sponge sites were excluded (e.g., Hogfish Lachnolaimus maximus). Efforts to mitigate survey interactions with live‐bottom habitats will likely alter the utility of survey data and the ability to assess managed species, so careful consideration is needed to evaluate any trade‐offs between the benefits of the trawl survey for fishery assessments and the benefits of protecting the habitat.

Seasonal and interannual variability in the density of the postlarvae of Litopenaeus setiferus and Farfantepenaeus duorarum in Términos Lagoon, Gulf of Mexico

Abstract 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.

Population Genomics of the Commercially Important Gulf of Mexico Pink Shrimp Farfantepenaeus duorarum (Burkenroad, 1939) Support Models of Juvenile Transport Around the Florida Peninsula

The Gulf of Mexico pink shrimp, Farfantepenaeus duorarum, supports large fisheries in the United States and Mexico, with nearly 7,000 tons harvested from the region in 2016. Given the commercial importance of this species, management is critical: in 1997, the southern Gulf of Mexico pink shrimp fishery was declared collapsed and mitigation strategies went into effect, with recovery efforts lasting over a decade. Fisheries management can be informed and improved through a better understanding of how factors associated with early life history impact genetic diversity and population structure in the recruited population. Farfantepenaeus duorarum are short-lived, but highly fecund, and display high variability in recruitment patterns. To date, modeling the impacts of ecological, physical, and behavioral factors on juvenile settlement has focused on recruitment of larval individuals of F. duorarum to nursery grounds in Florida Bay. Here, we articulate testable hypotheses stemming from a recent model of larval transport and evaluate support for each with a population genomics approach, generating reduced representation library sequencing data for F. duorarum collected from seven regions around the Florida Peninsula. Our research represents the first and most molecular data-rich study of population structure in F. duorarum in the Gulf and reveals evidence of a differentiated population in the Dry Tortugas. Our approach largely validates a model of larval transport, allowing us to make management-informative inferences about the impacts of spawning location and recruitment patterns on intraspecific genetic diversity. Such inferences improve our understanding of the roles of non-genetic factors in generating and maintaining genetic diversity in a commercially important penaeid shrimp species.

Diel Variability and Influence of Artificial Light on Fish and Macroinvertebrate Communities in Gulf of Mexico Seagrass Beds

Seagrasses are productive habitats that support diverse communities of economically and ecologically important fishes and macroinvertebrates. However, most seagrass faunal assessments are conducted only during daylight hours. Here, we documented diel patterns in seagrass-associated fish and macroinvertebrate community structure in seagrass near Seahorse Key, Florida (USA). Artificial light is prevalent in many coastal areas and may influence day/night assemblages; therefore, we added lights to the natural environment to get a better understanding of its effect on community composition. Seagrass inhabitants were quantified using 25-m seine transects during different diel periods (day or night) and in areas where light was manipulated to mimic light pollution (artificial + natural light or natural light). Results suggest that the magnitude of diel effects exceeded that of light addition. While total abundance was similar between day and night, communities did change, with Lagodon rhomboides (Pinfish) dominating day samples and Farfantepenaeus duorarum (pink shrimp) most abundant at night. Other fishes such as Orthopristis chrysoptera (Pigfish) and Strongylura notata (Needlefish) had higher catches during the day, while invertebrates such as Callinectes sapidus (blue crab) and Palaeomonetes spp. (grass shrimp) were more prominent at night. In addition to the differences in abundance and community structure, we also identified diel differences in sizes for some species. No clear patterns were observed with the short-term addition of artificial light. This research highlights the role of diel variability in seagrass communities and suggests that diel movement of organisms may represent an important conduit for the transfer of energy to adjacent habitats.

An abnormal rostrum in a wild subadult shrimp Farfantepenaeus duorarum (Burkenroad, 1939) (Decapoda, Penaeidae) from the southern Gulf of Mexico

Abstract An abnormal bifid rostrum is reported for the first time for a wild-caught subadult female (carapace length = 22.5 mm) of the pink shrimp Farfantepenaeus duorarum (Burkenroad, 1939) from Celestun lagoon, Yucatan, southern Gulf of Mexico. A review of registers on morphological abnormalities in shrimps of the family Penaeidae is provided.

Seasonal abundance and diel behavior of roughneck shrimps (species of Rimapenaeus Pérez Farfante & Kensley, 1997) (Decapoda: Dendrobranchiata: Penaeidae) in northwestern Florida Bay, Florida, USA

Abstract A large number of roughneck shrimps, Rimapenaeus Pérez Farfante & Kensley, 1997, were collected in northwestern Florida Bay, southern Florida over four consecutive years (2000–2003) of monthly sampling during new-moon periods. Juveniles of Rimapenaeus spp. were more abundant than pink shrimp Farfantepenaeus duorarum (Burkenroad, 1939) juveniles, which are well-recognized and abundant inhabitants of Florida Bay. High Rimapenaeus spp. abundance was unexpected because the genus was previously reported only as occasional in Florida Bay. The populations of Rimapenaeus spp. were composed of late postlarvae and immature juveniles, suggesting that the northwestern border of Florida Bay serves as a nursery ground for this species. A clear seasonal recruitment pattern was observed with large peaks of postlarvae and small juveniles occurring in summer-fall and large juveniles in spring. The summer-fall peaks occurred during months with high mean water level and sea surface temperature; these two factors significantly predicted Rimapenaeus spp. abundance. Overnight hourly behavioral studies revealed that Rimapenaeus spp. juveniles were almost exclusively present in the water column during the dark hours of the ebb tide during current speed minimum. Juvenile abundance significantly differed between moon phases with shrimps being virtually absent during the illuminated full moon. These results indicate that Rimapenaeus spp. are phototactic negative, which may explain the low presence of this species in previous Florida Bay surveys conducted during daylight hours. This study highlights the previously unrecognized contribution of the abundance of juveniles of Rimapenaeus spp. to benthic-oriented crustacean communities of western Florida Bay and its border at the southwestern Florida Shelf.

Spatial and temporal habitat use by penaeid shrimp (Decapoda: Penaeidae) in a coastal lagoon of the southwestern Gulf of Mexico

Knowledge of the environmental factors that influence the spatial–temporal densities of penaeid shrimp in Mecoacán 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 Mecoacán 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.

Relación longitud-peso, y factor de condición relativa de postlarvas epibentónicas y de jóvenes, del camarón rosado Farfantepenaeus duorarum (Crustacea: Penaeidae) en Laguna de Términos, México

The knowledge about the weight, length and condition factor of the organisms is key for explaining the population dynamics in wild animals. The present study was focused on finding the model that best explains the length-weight relationships in epibenthic and juveniles of Farfantepenaeus duorarum, as well as the condition factor during the different months sampled. In the study, 3 992 individuals (size range: 3.62-32.16 mm cephalothorax length) were collected from three different places at the Terminos Lagoon from May 2011 to March 2012. The individuals were grouped into three sex categories: male (M), female (H), and undefined (I), and their length-weight (L-P-1) relationship, as well as their relative condition factor, were determined. The results indicate that the total length-carapace length (LT-LC) relationship for each sex category was linear, there was no difference between the models for small males and females and the relationship can be expressed as (LT (M-H) = 1.89 + 4.46 LC). For the undefined group, the relationship was different and is best expressed as LT (I) = 0.07 + 4.62 LC. The potential model for the expression of Carapace Length-Weight in the M-H group was P = 0.0016 LC2.5323 or log (P) = 2.5323 log(LC) - 2.8079, R² = 0.9272 in the linear model. In the undefined group, the potential model was W = P = 0.0004LC3.2315 and the linear model was log (P) = 3.2315 log(LC) - 3.4365, R2 = 0.9422. On the other hand, the relative condition factor (Kn) differed among groups when the date was involved in the analysis. We consider that relative condition factor involving Total Length is better than relative condition factor including Carapace Length to measure population characteristics of shrimps and that index could contribute to evaluating the shrimp population dynamics.

Trophic Relationships and Niche Partitioning of Red Drum Sciaenops ocellatus and Common Snook Centropomus undecimalis in Coastal Estuaries of South Florida

Large marine predators occupying the same spatial arena exhibit a variety of temporal and behavioral differences to minimize competition for habitat and prey. Here, we examined two such species in the Florida Everglades, red drum Sciaenops ocellatus and snook Centropomus undecimalis, to evaluate niche separation based on diet and multiple stable isotope (white muscle, δ13C, δ15N, δ34S) analyses. For these two estuarine predators, our results indicated that although dietary niche overlap was broad, different feeding modes (spatial and behavioral) allow niche partitioning. The diet of red drum was dominated by pink shrimp Farfantepenaeus duorarum and other demersal species. For snook, although their diet included significant numbers of pink shrimp, it was largely dominated by pelagic and epibenthic fishes. Mean red drum δ13C signatures (− 10.5 to − 20.8‰) differed significantly between areas and were strongly correlated with both area-specific seagrass concentration and amount of incidental seagrass ingestion. Mean snook δ13C signatures were generally depleted (− 20.9 to − 22.4‰) with the exception of one area (− 14.1‰). Red drum and snook diet and mean δ15N signatures (10.1‰, 10.8‰, respectively) indicated they were both mid-trophic-level consumers. Mean red drum δ34S signatures were significantly depleted (− 0.31‰) in the seagrass-dominated area, but enriched (2.03 to 3.78‰) in the other areas and indicated benthic but no pelagic sources of primary production. Mean snook δ34S signatures varied widely (0 to 20‰) among areas suggesting dependence on benthic (benthic algae and seagrass) and pelagic (phytoplankton) sources of primary production.

Pink shrimp Farfantepenaeus duorarum spatiotemporal abundance trends along an urban, subtropical shoreline slated for restoration.

The Biscayne Bay Coastal Wetlands (BBCW) project of the Comprehensive Everglades Restoration Plan (CERP) aims to reduce point-source freshwater discharges and spread freshwater flow along the mainland shoreline of southern Biscayne Bay. These actions will be taken to approximate conditions in the coastal wetlands and bay that existed prior to construction of canals and water control structures. An increase in pink shrimp (Farfantepenaeus duorarum) density to ≥ 2 individuals m-2 during the wet season (i.e., August-October) along the mainland shoreline was previously proposed as an indication of BBCW success. This study examined pre-BBCW baseline densities and compared them with the proposed target. Densities were monitored by seasonal (wet, dry) throw-trapping (1 m2 replicated in triplicate) at 47 sites along ~22 km of the southwestern Biscayne Bay coastline over 10 years (2007–2016). Densities varied across years and were most often higher in dry seasons. Quantile regression revealed density limitation by four habitat attributes: water temperature (°C), depth (m), salinity (ppt), and submerged aquatic vegetation (SAV: % cover). Procrustean analyses that tested for concordance between the spatial and temporal distributions of shrimp densities and habitat metrics found that water temperature, water depth, and salinity explained ~ 28%, 28%, and 22% of density variability, respectively. No significant relationship with SAV was observed. Hierarchical clustering was used to identify spatially and temporally similar groupings of pink shrimp densities by sites or season-years. Significant groupings were then investigated with respect to potentially limiting habitat attributes. Six site and four year-season clusters were identified. Although habitat attributes significantly differed among spatial clusters, within-cluster median pink shrimp densities did not correlate with within-cluster minima, maxima, medians, or standard deviations of habitat attributes. Overall, pink shrimp density ( = 0.86, SD = 1.32 shrimp m-2) was significantly lower (t(α = 0.10,2),939 = -26.53, P <0.0001) than the 2 shrimp m-2 CERP Interim Goal target. Pink shrimp density corresponded significantly with salinity and appeared limited to density < 2 shrimp m-2 by salinity < ~18 ppt. Salinity is an environmental attribute that will be directly influenced by CERP implementation.

Monitoring mangrove forest dynamics in Campeche, Mexico, using Landsat satellite data

The mangrove forests of Campeche, Mexico, are important facets of the regional ecology and economy. In addition to supporting commercially fished populations of pink shrimp (Farfantepenaeus duorarum), white shrimp (Litopenaeus satiferus), and octopus (Octopus spp.), the area's coastal mangroves and associated seagrass flats provide crucial habitat for juvenile tarpon (Megalops atlanticus), for which Campeche is a burgeoning destination for catch-and-release sport fishing. Mexico's total mangrove area has decreased by more than 20% throughout the past two decades, but no previous study has specifically mapped mangrove change dynamics in Campeche. To address this gap in the literature, this study used unsupervised classification of Landsat satellite data from 1999 and 2016 to map and quantify mangrove forest cover changes along Campeche's coast and worked with local fishing guides to identify regional drivers of mangrove degradation. Results demonstrated a 14.10% decrease in mangrove area and a 19.09% increase in Campeche city's urban extent during the study period. Mangrove decline was concentrated in coastal fringes, with local informants indicating that much of the degradation resulted from localized alteration of mangrove channels’ water flows due to road construction projects, as well as increased indirect pressures from Campeche's expanding population. Importantly, these results indicate that although Campeche's coastal mangrove corridor is protected as a UNESCO Biosphere Reserve, its close proximity to the large and growing urban center of Campeche city makes it vulnerable to direct and indirect drivers of mangrove degradation. Future updates to this study's results will be essential to monitoring Campeche's mangroves’ ongoing responses to the dueling influences of increased anthropogenic pressures and localized mangrove restoration initiatives.

Causes, Diagnostics, and Distribution of an Ongoing Penaeid Shrimp Black Gill Epidemic in the U.S. South Atlantic Bight

ABSTRACT 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...

Natural cultch type influences habitat preference and predation, but not survival, in reef‐associated species

AbstractA shared origin with fresh and dredged cultch and availability via mining have made fossil cultch a commonly used reef restoration substrate. However, important differences in shape and size between whole‐shell cultch and fossil cultch may impact the complexity of reefs constructed from these materials. To determine if these differences may impact the development of restored reefs, we quantified the interstitial space each cultch type provides and constructed reef mesocosms to measure (1) the immediate effects of exposure to each cultch type on mortality of blue crab (Callinectes sapidus) and pink shrimp (Farfantepenaeus duorarum); (2) the tendency of crab, shrimp, and Florida crown conch (Melongena corona) to be found on habitats composed of each substrate type and their position within each in split‐substrate mesocosms; and (3) the influence of cultch type on predation of Eastern oysters (Crassostrea virginica) by crabs and conch. Aggregation of fossil cultch contains more shells and provides less interstitial space than an equivalent volume of whole‐shell cultch. Although immediate mortality following deployment was low and did not differ among cultch types, we found that all species were more likely to be found on fresh cultch over fossil cultch in choice experiments and used each habitat type differently. Cultch type also impacted the size of oysters consumed by crabs in short‐term feeding trials. The structure and traits of habitats created by various materials should be added to the growing list of issues considered when natural communities are to be restored in oyster reefs and other environments.

Effects of Exposure of Pink Shrimp, Farfantepenaeus duorarum, Larvae to Macondo Canyon 252 Crude Oil and the Corexit Dispersant

The release of oil into the Gulf of Mexico (GOM) during the Deepwater Horizon event coincided with the white and pink shrimp spawning season. To determine the potential impact on shrimp larvae a series of static acute (24–96 h) toxicity studies with water accommodated fractions (WAFs) of Macondo Canyon (MC) 252 crude oil, the Corexit 9500A dispersant, and chemically enhanced WAFS (CEWAFs) were conducted with nauplii, zoea, mysid, and postlarval Farfantepenaeus duorarum. Median lethal concentrations (LC50) were calculated and behavior responses (swimming, molting, light sensitivity) evaluated. Impacts were life stage dependent with zoea being the most sensitive. Behavioral responses for all stages, except postlarvae, occurred at below LC50 values. Dispersants had the greatest negative impact while WAFs had the least. No short-term effects (survival, growth) were noted for nauplii exposed to sub-lethal CEWAFs 39 days post-exposure. This study points to the importance of evaluating multiple life stages to assess population effects following contaminant exposure and further, that the use of dispersants as a method of oil removal increases oil toxicity.

Using Delta‐Generalized Additive Models to Predict Spatial Distributions and Population Abundance of Juvenile Pink Shrimp in Tampa Bay, Florida

AbstractIn this article, we present an approach based on generalized additive models (GAMs) to predict species’ distributions and abundance in Florida estuaries with habitat suitability modeling. Environmental data gathered by fisheries‐independent monitoring in Tampa Bay from 1998 to 2008 were interpolated to create seasonal habitat maps for temperature, salinity, and dissolved oxygen and annual maps for depth and bottom type. We used delta‐GAM models assuming either zero‐adjusted gamma or beta‐inflated‐at‐zero distributions to predict catch per unit effort (CPUE) from five habitat variables plus gear type for each estuarine species by life stage and season. Bottom type and gear type were treated as categorical predictors with reference parameterization. Three spline‐fitting procedures (the penalized B‐spline, cubic smoothing spline, and restricted cubic spline) were applied to the continuous predictors. Two additive, linear submodels on the log and logistic scales were used to predict CPUEs &gt;0 and CPUEs = 0, respectively, across environmental gradients. The best overall model among those estimated was identified based on the lowest Akaike information criterion. A stepwise routine was used to omit continuous predictors that had little predictive power. The model developed was then applied to interpolated habitat data to predict CPUEs across the estuary using GIS. The statistical models, coupled with the use of GIS, provide a method for predicting spatial distributions and population numbers of estuarine species’ life stages. An example is presented for juvenile pink shrimp Farfantepenaeus duorarum during the summer in Tampa Bay, Florida.Received February 10, 2015; accepted August 11, 2015

Linking Oceanographic Modeling and Benthic Mapping with Habitat Suitability Models for Pink Shrimp on the West Florida Shelf

AbstractResearch was undertaken to model and map the spatial distributions and abundances of pink shrimp Farfantepenaeus duorarum on the West Florida Shelf (WFS) using habitat suitability modeling (HSM). Data loggers and electronic logbook systems on three shrimp boats were used to gather catch and effort data along with bottom temperature, salinity, and depth data at the fishing locations. Vessel monitoring system (VMS) data supplied by the fishing company helped delineate areas with high fishing activity. For the vessels participating in this study, significantly higher mean catch per unit effort (CPUE) of pink shrimp was realized on the WFS during June–September 2004 and October–December 2004 than during January–March 2005 and April–June 2005. Suitability functions were created to predict CPUE in relation to depth, aspect, bottom type, bottom temperature, current speed, current direction, and VMS zone. Oceanographic modeling was conducted monthly from March 2004 to June 2005. Bottom current speed and d...

Modeling Larval Transport and Settlement of Pink Shrimp in South Florida: Dynamics of Behavior and Tides

AbstractThe pink shrimp Farfantepenaeus duorarum, one of the commercially important Penaeidae, reproduces offshore of the southwest Florida (SWF) shelf. Larvae migrate to nursery grounds in estuarine Florida Bay. Using a numerical approach, we investigated the role of spawning location, larval traits, and physical forces on the transport of pink shrimp larvae. First, the Regional Oceanic Modeling System that is based on tides, air–ocean fluxes, and freshwater flows was used to simulate the SWF shelf oceanography. The model replicates the tides, winds, salinity, currents, and seasonality of the shelf. Secondly, the Regional Oceanic Modeling System was coupled offline with the Connectivity Modeling System, in which virtual larvae were released near the surface from two spawning sites, Dry Tortugas and Marquesas, and tracked until the time for settlement (about 28–30 d). Virtual larvae moved vertically in the water column following ontogenetic behaviors previously observed in the field: diel vertical migration (DVM) and selective tidal stream transport (STST). Lagrangian trajectories indicated that migration paths changed radically between summer and winter during model years (1995–1997). Maximum settlements occurred in summer by larvae crossing the SWF shelf, while the lowest settlement occurred in winter by larvae moving through passes in the Florida Keys. Modeling results demonstrated an effective east‐northeast transport across the SWF shelf during summer as a result of the tidal currents, the subtidal currents, and the combined DVM and STST behaviors. The current phase captured during the initial DVM period was critical to determine the direction in which larvae move, favorable (east and northward) or unfavorable (south and westward), before the STST behavior captures the eastward tidal current that brings larvae to the nursery grounds. Unfavorable currents were driven by the summer easterlies and low salinities at the coast. Results indicated that Marquesas is the more effective spawning ground, with 4.5 times more likely settlement of originating larvae compared with Dry Tortugas. Model‐estimated seasonal settlement patterns concurred with postlarval influxes previously observed at Florida Bay boundaries.Received June 26, 2014; accepted December 7, 2014

Using delta generalized additive models to produce distribution maps for spatially explicit ecosystem models

Spatial ecosystem models, such as OSMOSE, have become integral tools in achieving ecosystem-based management for their ability to thoroughly describe predator–prey dynamics in a spatially explicit context. Distribution maps, which define the initial spatial allocation of functional groups abundance, can have a large effect on the predator–prey dynamics that spatially explicit ecosystem models simulate. Here, we introduce the delta GAM approach we developed to be able to produce distribution maps for an OSMOSE model of the West Florida Shelf (Gulf of Mexico), OSMOSE-WFS. This delta GAM approach predicts the spatial distribution of different life stages of the multiple functional groups represented in OSMOSE-WFS (‘life-stage groups’) at different seasons, over the entire Gulf of Mexico (GOM) shelf including areas where abundance estimates do not exist, using different research survey datasets and regional environmental and habitat features. Our delta GAM approach consists of fitting two independent models, a binomial GAM and a quasi-Poisson GAM, whose predictions are then combined using the delta method to yield spatial abundance estimates. To validate delta GAMs, bootstraps are used and Spearman's correlation coefficients (Spearman's ρ’s) between predicted and observed abundance values are estimated and tested to be significantly different from zero. We use pink shrimp (Farfantepenaeus duorarum) to demonstrate our delta GAM approach by predicting the summer distribution of this species over the GOM shelf and the West Florida Shelf. Predictions of the delta GAM reflect existing empirical research related to pink shrimp habitat preferences and predictions of a negative binomial GAM previously designed for the GOM. We find that using a delta rather than a negative binomial GAM saves significant computation time at the expense of a slight reduction in GAM performance. A positive and highly significant Spearman's ρ between observed and predicted abundance values indicates that our delta GAM can reliably be used to predict pink shrimp spatial distribution. Spearman's ρ was also positive and highly significant in every life-stage group represented in OSMOSE-WFS and season, though often low. Therefore, delta GAMs fitted for the different life-stage groups and seasons correctly predict qualitative differences between low- and high-abundance areas and are deemed appropriate for generating distribution maps for OSMOSE-WFS. The delta GAM approach we developed is a simple, convenient method to create distribution maps to be fed into spatially explicit ecosystem models, where wide spatial and taxonomic coverage is desired while benefits of high precision estimates are lost at run-time.

Efecto de la temperatura superficial y la salinidad en el reclutamiento del camarón rosado Farfantepenaeus duorarum (Decapoda: Penaeidae), en la Sonda de Campeche, Golfo de México

We studied the long term effects of two environmental variables, salinity and surface temperature, on the pink shrimp (Farfantepenaeus duorarum) population in the southern Gulf of Mexico, considering the relationship between recruiting and the concurrent shrimp stock depletion of the last two decades. Our data were collected from 1969 to 1991. Recruitment has been clearly declining, particularly in the 1970s, with an accentuated drop since the 1980s. Sea surface temperatures have steadily risen, particularly since 1972. The temperature difference between the mid 1970s and the late 1980s is 0.5 degree C. Salinity decreased throughout the period. From a long term perspective, recruitment is negatively correlated with temperature and positively correlated with salinity. The effects of temperature and salinity are statistically significant, explaining 52 % and 55 % of the variation in recruitment, respectively.

Influence of Temperature and Salinity on Growth, Survival, and Biomass Productivity of Postlarval and Early Juvenile Pink Shrimp Farfantepenaeus duorarum (Burkenroad 1939)

ABSTRACT An investigation was conducted of the combined effect of salinity and temperature on growth, survival, and biomass productivity of postlarval and early juvenile pink shrimp Farfantepenaeus duorarum (Burkenroad 1939) produced from a single spawning event. The study used a factorial block design consisting of three salinity treatments (15, 35, and 55), each replicated, within three temperature treatment (22°C, 27°C, and 32°C) water baths. The study was divided into two phases: postlarval (first 28 days) and early juvenile (second 28 days). Growth was assessed every 7 days throughout the experiment by measuring carapace length (CL) and wet weight (WWT) of 15 randomly selected shrimp from each temperature/salinity replicate tank. After the first study phase, survival was assessed and experimental aquaria were reset with 30 randomly selected shrimp from the same temperature—salinity replicates. Survival was assessed again at the end of the early juvenile phase. The effect of treatments was evaluated b...