Daggerblade Grass Shrimp Palaemonetes Pugio Research Articles

The Effect of Temperature on Synchronization of Brood Development of the Bopyrid Isopod Parasite Probopyrus pandalicola with Molting of Its Host, the Daggerblade Grass Shrimp Palaemonetes pugio.

The bopyrid isopod Probopyrus pandalicola is a hematophagous ectoparasite that sexually sterilizes some palaemonid shrimps, including female daggerblade grass shrimp Palaemonetes pugio. The reproduction of parasitic isopods is thought to occur synchronously with host molting because the brood would be unsuccessful if molting occurred before the larvae were free swimming. Temperature affects the length of the molting cycle of shrimp, and therefore may also affect the incubation time of isopod broods. The purpose of the present study was to determine the effect of temperature on brood development of the parasite and on the degree of synchronization with the molting of its host. Parasitized P. pugio were monitored daily at 2 experimental temperatures, 23 and 15 C, in temperature-controlled chambers for the duration of a full parasite reproductive cycle. Developmental stage was determined by the visible coloration of the brood through the exoskeleton of the host, and was designated as egg, embryo I, embryo II, or epicaridium larvae. Temperature significantly affected median brood incubation time, which was only 11 days at 23 C, as compared to 35 days at 15 C. The final developmental stage (epicaridium larvae) was 3 times shorter at 23 C (median 3 days; n = 45) than at 15 C (median 9 days; n = 15). Temperature significantly affected the intermolt period of parasitized shrimp, which was shorter at 23 C (median 12 days) than at 15 C (median 37 days). A smaller percentage of the intermolt period elapsed between larval release and shrimp molting at 23 C (0.0%) than at 15 C (3.1%), indicating closer synchronization between host molting and parasite reproduction at the warmer temperature. At 15 C, the isopods utilized a smaller proportion of the time that was available for brood incubation during the intermolt period of their host. Brood size ranged from 391 to 4,596 young and was positively correlated with parasite and host size. Because development progressed more rapidly at 23 C, warmer temperatures could increase the prevalence of P. pandalicola. The corresponding reduction in the abundance of ovigerous grass shrimp as a result of sexual sterilization by bopyrids could adversely impact estuarine ecosystems, as grass shrimp are a crucial link in transferring energy from detritus to secondary consumers.

Sexual sterilization of the daggerblade grass shrimp Palaemonetes pugio (Decapoda: Palaemonidae) by the bopyrid isopod Probopyrus pandalicola (Isopoda: Bopyridae).

Probopyrus pandalicola is a bopyrid isopod that infects several palaemonid shrimp species, including the daggerblade grass shrimp Palaemonetes pugio . The parasite can have several negative effects on its host, including loss of hemolymph, reduced reproductive potential, and decreased molting frequency and growth. To date, there are conflicting reports on whether Probopyrus pandalicola affects the reproductive capability of both male and female daggerblade grass shrimp. The purpose of this study was to determine whether infection by Probopyrus pandalicola resulted in the sexual sterilization of Palaemonetes pugio , and if the reproductive capability of male and/or female shrimp was restored after the bopyrid was removed. We found that parasitized and deparasitized males were able to fertilize the eggs of unparasitized females successfully, as 18.9 ± 7.1% and 42.7 ± 5.2% of the females paired with them became ovigerous in 4 wk, respectively. Neither parasitized nor deparasitized females became ovigerous when placed with unparasitized males during the 4-wk period. However, 45.4 ± 20.6% of deparasitized females did become ovigerous within 10 wk. Despite the fact that female shrimp are able to reproduce again when no longer parasitized, the majority of females remain infected with the bopyrid for their entire lives. Therefore, the sexual sterilization of female shrimp could potentially have a significant impact on estuarine food webs, as grass shrimp are conduits of detrital energy and a food source for many recreationally and commercially important species in estuaries on the East Coast of the United States and in the Gulf of Mexico.

Decapod Utilization of Adjacent Oyster, Vegetated Marsh, and Non-Vegetated Bottom Habitats In A Gulf of Mexico Estuary

Abstract 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. ...

Using nekton growth as a metric for assessing habitat restoration by marsh terracing

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.

Marsh terracing as a wetland restoration tool for creating fishery habitat

Terracing is a relatively new wetland-restoration technique used to convert shallow subtidal bottom to marsh. This method uses existing bottom sediments to form terraces or ridges at marsh elevation. A terrace field is constructed by arranging these ridges in some pattern that maximizes intertidal edge and minimizes fetch between ridges; the intertidal area is planted with marsh vegetation. We examined the habitat value of terracing for fishery species at Sabine National Wildlife Refuge, Louisiana (USA) in spring and fall 1999 by quantifying and comparing nekton densities in a 9-yr-old terrace field and nearby reference area using a 1-m2 drop sampler. Decapod crustaceans were more abundant than fishes, composing 62% and 95% of all organisms we collected in spring and fall, respectively. White shrimp Litopenaeus setiferus, daggerblade grass shrimp Palaemonetes pugio, blue crab Callinectes sapidus, and brown shrimp Farfantepenaeus aztecus accounted for 94% of all crustaceans, whereas 60% of all fishes were gulf menhaden Brevoortia patronus. Mean densities of white shrimp (fall), daggerblade grass shrimp, blue crab, and brown shrimp (spring) were significantly greater in terrace marsh than on non-vegetated bottom in the reference pond. Densities of most nekton on non-vegetated bottom were similar in the terrace field and the reference pond, but gulf menhaden and white shrimp had higher densities at terrace pond sites and brown shrimp (spring) were more abundant at reference pond sites. The pattern for biomass was similar to that for density in that the mean biomass of most species was significantly greater at terrace marsh sites than reference pond sites and similar at terrace and reference pond sites. Terrace marsh, however, was not functionally equivalent to natural marsh, as mean densities of daggerblade grass shrimp (fall), brown shrimp (spring), and blue crab and mean biomass of white shrimp (fall), striped mullet Mugil cephalus (spring), and spotted seatrout Cynoscion nebulosus (fall) were greater at reference marsh sites than terrace marsh sites. Using these density and biomass patterns and the percentage of marsh and pond area in the terrace field, we concluded that terrace fields support higher standing crops of most fishery species compared with shallow marsh ponds of similar size. Future restoration projects could include design changes to increase the proportion of marsh in a terrace field and enhance the habitat value of marsh terraces for fishery species.

Life cycle of Calyptospora funduli (Apicomplexa: Calyptosporidae).

The taxonomic status of the extraintestinal piscine coccidium Calyptospora funduli is based in part on its requirement of an intermediate host (the daggerblade grass shrimp Palaemonetes pugio). In the present study, grass shrimp fed livers of Gulf killifish (Fundulus grandis) infected with sporulated oocysts of C. funduli exhibited numerous sporozoites suspended in the intestinal contents when fresh squash preparations were examined by light microscopy. Using this method, sporozoites were not seen in intestinal epithelial cells of the grass shrimp or in any other cell types. Ultrastructural examination, however, revealed sporozoites in the cytoplasm of the gut basal cells. Cross-sections of 1-13 sporozoites were seen within a single cell, and those sporozoites each appeared to be situated in individual membrane-bound vesicles, rather than in a single parasitophorous vacuole. These ultrastructural observations indicate that in the grass shrimp intermediate host, sporozoites that develop into an infective stage probably undergo that development in gut mucosal basal cells. Prior studies revealed that these sporozoites modified their structure over 4-5 days and that before that time, they were not infective to the fish host. Following ingestion of an infected shrimp by a killifish, the infective sporozoites apparently reach the liver of their killifish definitive hosts through the bloodstream. Sporozoites were seen in blood smears from the longnose killifish, Fundulus similis, 4 hr after fish were fed experimentally infected grass shrimp. Additionally, coccidian trophozoites and early meronts were seen in hepatocytes from several longnose killifish at 48, 72, and 96 hr postinfection. This study, in conjunction with previous findings, clearly confirms that a true intermediate host is required in the life cycle of C. funduli, that a developmental period of about 5 days in grass shrimp is necessary for sporozoites to become infective to killifishes, and that sporozoites do occur intracellularly in gut basal cells of the grass shrimp.

Small-scale patterns of nekton use among marsh and adjacent shallow nonvegetated areas of the Galveston Bay Estuary, Texas (USA)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 193:217-239 (2000) - doi:10.3354/meps193217 Small-scale patterns of nekton use among marsh and adjacent shallow nonvegetated areas of the Galveston Bay Estuary, Texas (USA) Lawrence P. Rozas*, Roger J. Zimmerman NOAA/National Marine Fisheries Service, Southeast Fisheries Science Center, 4700 Avenue U, Galveston, Texas 77551-5997, USA *E-mail: lawrence.rozas@noaa.gov ABSTRACT: We quantified and compared nekton and infaunal densities among vegetated (edge Spartina alterniflora, inner Spartina alterniflora, Scirpus maritimus, Juncus roemerianus, and Spartina patens marsh) and shallow nonvegetated (marsh pond, marsh channel, cove, and shallow bay) areas of upper Galveston Bay and East Bay, Texas. In 2 seasons (spring and fall) of high nekton abundance, and over 2 yr, we collected 267 quantitative samples (upper Galveston Bay, 1993 = 127 and East Bay, 1994 = 140) using a 1 m2 drop sampler. The vegetated marsh surface consistently contained more species (i.e. higher species richness) and total numbers of decapod crustaceans than nonvegetated areas. In contrast, fish species richness and densities of total fishes on the marsh and in nonvegetated areas were not significantly different in most comparisons. Most numerically dominant species of nekton seemed to exhibit at least some degree of habitat selection. Within vegetation, 2 factors, elevation and proximity to open water, were most important in influencing the distribution of nekton. Low marsh edge dominated by Spartina alterniflora or Scirpus maritimus was apparently selected by most species that used the marsh surface including brown shrimp Farfantepenaeus aztecus, blue crab Callinectes sapidus, and daggerblade grass shrimp Palaemonetes pugio. White shrimp Litopenaeus setiferus and striped mullet Mugil cephalus also were concentrated in low edge marsh; although in one comparison, densities of these 2 species in edge and inner S. alterniflora were not significantly different. In contrast, gulf killifish Fundulus grandis and sheepshead minnow Cyprinodon variegatus were most abundant on inner S. alterniflora or S. patens marsh. Other fishes (gulf menhaden Brevoortia patronus, spot Leiostomus xanthurus, bay anchovy Anchoa mitchilli, blackcheek tonguefish Symphurus plagiusa, and Atlantic croaker Micropogonias undulatus) had higher densities over nonvegetated bottoms than on the marsh surface. Specific habitat types that these pelagic species seemed to favor were marsh channels (gulf menhaden, bay anchovy), marsh ponds (spot), and coves (Atlantic croaker, blackcheek tonguefish). Overall, marsh-surface and adjacent nonvegetated habitat types contained much higher densities of most nekton than the shallow bay. Infaunal densities were estimated from sediment cores, and taxa (mainly annelids, crustaceans, molluscs, and insects) were most abundant in nonvegetated areas contiguous with marsh in the spring. Factors that influenced infaunal abundance are complex and may include predation, flooding patterns, elevation, and distance to edge. Our study has important implications for designing marsh-creation projects. Based on our results, we recommend creating a variety of marsh and contiguous shallow-water areas to enhance nekton biodiversity. To maximize fishery habitat, priority should be given to constructing low marsh edge by creating large areas of low marsh interspersed with a dense network of shallow channels and interconnected ponds. KEY WORDS: Fishery species · Gulf of Mexico · Habitat comparisons · Habitat selection · Nursery areas · Penaeid shrimps · Tidal marsh · Restoration Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 193. Publication date: February 28, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Toxicity of Scrap Tire Leachates in Estuarine Salinities: Are Tires Acceptable for Artificial Reefs?

Shredded scrap tires were leached in a modified toxicity characteristic leaching procedure (TCLP) extraction method in synthetic saltwater solutions for three sequential 7-d periods. Test salinities were 5, 15, and 25‰. Acute toxicity tests were conducted with larval sheepshead minnows Cyprinodon variegatus and daggerblade grass shrimp Palaemonetes pugio. Mortality decreased following multiple sequential leaching periods. Toxicity decreased with increasing salinity. The fish were more sensitive than the grass shrimp. Dilution series toxicity bioassays were performed with fish and grass shrimp at 5‰ salinity and at 15‰ with fish only. The 96-h LC50s (lethal concentration for half of the test animals) for fish were 10% leachate at 5‰ and 26% at 15‰. The 96-h LC50 for grass shrimp at 5‰ was 63%. The 96-h lowest observed effect concentrations (LOEC) for fish survival were 12.5% at 5‰ and 25% at 15‰. The 96-h LOEC for grass shrimp survival was 50% at 5‰. Growth LOEC values were 12.5% at both salinities for fish and 50% for grass shrimp at 5‰. Chemical analyses revealed no specific components as the cause of observed toxicity. Antagonism between sea salt and toxic chemicals is hypothesized to cause differential toxicity at varying salinities, as opposed to differential solubility of the toxicants. Extrapolation of laboratory results indicates that proposed tire reefs should not pose a serious threat to water quality in Chesapeake Bay. No observed effects concentrations (NOEC) were an order of magnitude or greater above field concentrations calculated from simplified methods. Toxic substances appear to leach from the surface of the tires not from the tire matrix. The use of tires in higher salinity environments appears to pose little direct toxicological risk to resident organisms. However, because unknown toxic chemicals were present in leachates at all test salinities, no assessment can be made regarding persistence, fate, transport, or possible bioaccumulative effects.

Composition and abundance of resident marsh-surface nekton: comparison between tidal freshwater and salt marshes in Virginia, USA

Previous research on intertidal nekton communities has identifiedimportant determinants of community structure and distribution; however, fewstudies have compared nekton utilization of disparate marsh habitats. Inthis study, abundance and distribution patterns of resident nekton werecompared between tidal freshwater marsh and salt marsh surfaces varying inflooding depth and duration. Nekton were collected in pit traps installedalong elevational transects at four marshes in coastal Virginia (twofreshwater, two saline) from April through November 1992–1993. Thedominant fish collected at all sites was the mummichog Fundulusheteroclitus. The daggerblade grass shrimp Palaemonetes pugio was thedominant nekton species collected at salt marsh sites, and was seasonallyabundant on tidal freshwater marshes. A positive correlation betweenflooding depth and nekton abundance was observed on salt marshes; anopposite pattern was observed on tidal freshwater marshes. Tidal floodingregime influences the abundance of resident nekton, however, the effect maybe confounded by other environmental variables, including variation insurface topography and seasonal presence or absence of submerged aquaticvegetation (SAV) in adjacent subtidal areas. In mid-Atlantic tidalfreshwater wetlands, SAV provides a predation refuge and forage site forearly life stages of marsh-dependent nekton, and several species utilizethis environment extensively. Salt marshes in this region generally lackdense SAV in adjacent subtidal creeks. Consequently, between-sitedifferences in species and size-specific marsh surface utilization byresident nekton were observed. Larvae and juveniles represented 79%and 59% of total fish collected at tidal freshwater and salt marshsites, respectively. The resident nekton communities of tidal freshwater andsalt marsh surfaces are characterized by a few ubiquitous species with broadenvironmental tolerances.

Relative effects of turbidity and light intensity on reactive distance and feeding of an estuarine fish

Gulf killifish Fundulus grandis were allowed to prey on daggerblade grass shrimp Palaemonetes pugio in clear water with bright light, turbid water containing bentonite clay, and clear water treatments where the light intensity was adjusted to match that in the bottom of the turbid tanks. Significantly fewer shrimp were consumed in the turbid tanks relative to the clear and shade treatments where predation rates did not differ significantly. The results suggested that the influence of suspended particles on predation rates was a consequence of light scattering and was not related to a decrease in light intensity. Reactive distances were subsequently determined for human observers viewing a small target in elongated tanks containing turbid water (7.3–60.5 NTU) under conditions of both low (8-10 μE m−2 s−1) and high illumination (153–1249 μE M−2 s−1). Reactive distance was primarily governed by turbidity while light intensity had little influence except at low turbidities. The shape of the relationship between reactive distance and turbidity for humans resembled curves reported for a variety of fish species.

Stage-structured interactions between seasonal and permanent residents of an estuarine nekton community.

Estuarine assemblages of fishes and natant decapod crustaceans (i.e. nekton) comprise both permanent resident species and juveniles of coastal marine species that use estuaries primarily as nurseries. In an attempt to understand how the young of marine species successfully invade communities of permanent estuarine residents we studied potential interactions between two of the most abundant decapod crustaceans in nekton assemblages of the southeastern United States. Three years of quantitative samples from an intertidal marsh on Sapelo Island, Georgia showed that densities of the resident daggerblade grass shrimp Palaemonetes pugio were reduced during the time that juvenile white shrimp Penaeus setiferus used the estuary as a nursery. Results of a field enclosure experiment showed that white shrimp had no significant lethal or sublethal effects on adult grass shrimp. However, they did reduce survival of both juvenile and larval grass shrimp in laboratory experiments, suggesting the potential importance of a stage-dependent predatorprey interaction between the two shrimp species. The mortality rate of young grass shrimp in the presence of white shrimp was unaffected by grass shrimp density, but larvae (2.6-3.0 mm) suffered higher mortalities than did juveniles (5.0-15.0 mm). We suggest that the vulnerability of grass shrimp to predation by white shrimp is related to their molting cycle. The 'window of vulnerability' opens more often for younger grass shrimp because they molt more frequently. When combined with losses due to other predators and competitors, the impact of early white shrimp cohorts on grass shrimp larvae and juveniles may prevent the resident species from maintaining its population at high densities, thereby freeing resources in the nursery for subsequent cohorts of juvenile white shrimp.

Comparing nekton assemblages of subtidal habitats in pipeline canals traversing brackish and saline marshes in coastal Louisiana

Subtidal habitats of pipeline canals in Louisiana brackish and saline marshes were sampled seasonally (fall, spring, and summer) between October 1991 and March 1993 with a 2-m2 throw trap to identify dominant natant species and test hypotheses relating habitat selection to water depth. Densities of nekton were compared among canals and between shallow ( -1m) areas within canals to test two null hypotheses: H1: Densities of nekton in pipeline canals are not related to maximum canal depth and H2: Densities of nekton in shallow and deep subtidal areas of canals are equal. Daggerblade grass shrimpPalaemonetes pugio, bay anchovyAnchoa mitchilli, blue crabCallinectes sapidus, brown shrimpPenaeous aztecus, and gulf menhadenBrevoortia patronus numericallly dominated nekton assemblages in both brackish and saline canals. Naked gobyGobiosomabosc, rainwater killifishLucania parva, and gulf pipefishSyngnathus scovelli were dominant only in brackish canals, whereas white shrimpPelaeus setiferus and Atlantic croakerMicropogonias undulatus were abundant in saline canals only. Although variation in the abundance of most numerically dominant species could not be related to maximum canal depth, the distribution of several species within pipeline canals was influenced by habitat depth and other interrelated factors. The degree of habitat segregation with depth was largely influenced by submerged aquatic vegetation (SAV) and salinity as well as water depth. Habitat segregation with depth was most pronounced in brackish canals during late spring (May) when SAV was present. Naked goby, rainwater killifish, blue crabs, and daggerblade grass shrimp were significantly more abundant in shallow water (<1 m) at this time. In saline canals, most blue crabs and daggerblade grass shrimp occupied shallow habitats in March when small juveniles of these species reached peak abundance. Bay anchovy exhibited a pattern opposite that of other species. In March, bay anchovy abundance was positively related to maximum canal depth in brackish canals, and densities were greater in deep than shallow areas of saline canals in June. Salinity may have affected the distribution of freshwater species (e.g., centrarchids) and limited their occurrence in saline canals. Increasing shallow subtidal habitat by backfilling canals may enhance the nursery habitat for some species, especially in brackish canals where the area of subtidal habitat capable of supporting SAV would be expanded.