Mollusks taken by Beam Trawl in the vicinity of Gray's Reef National Marine Sanctuary on the Continental Shelf off Georgia, Southeastern U.S.

Mollusks were sorted from samples of shell hash (obtained as bycatch during NOAA-sponsored studies of larval and juvenile fish distribution), and analyzed to gain qualitative insights on species composition, distribution and habitat affinities of the molluscan fauna on the continental shelf off Georgia. Samples came from beam trawls at 37 stations located in the immediate vicinity and offshore of the Gray’s Reef National Marine Sanctuary (GRNMS) at depths of 4.9 to 103 m. Two hundred sixty-three (263) taxa of mollusks (~58% as dead shells only) were collected, and nearly all (~99%) were identified to the species level. Ninety-seven of these taxa appeared in samples from one or more of the four stations established near the corners of the GRNMS. Samples were highly variable in terms of appearance, volume and species composition of mollusks, reflecting the extreme patchiness of benthic habitats within this region of the continental shelf. With very few exceptions, the mollusks were generally characteristic of either the Carolinian or Caribbean faunal provinces. The Georgia continental shelf, however, was outside the previously reported ranges for at least 16 of the species reported here. Most of these extralimital species were known previously from the East Coast of Florida, and represented northerly range extensions of 1-5° Latitude (110-560 km). One species represented a more significant range extension from the Bahamas and the southern Caribbean, and two represented southerly range extensions, known previously from only as close as off North Carolina. The high incidence of range extensions found in this study and the potential for discovery of additional species are discussed in the context of the diversity and patchiness of benthic habitats on the continental shelf of the region, and the sensitivity of species recruitment to variability in Gulf Stream patterns and global climate change. (PDF contains 52 pages)

White spot syndrome virus (WSSV) transmission risk through infected cooked shrimp products assessed by polymerase chain reaction (PCR) and bio-inoculation studies

The aim of the study was to evaluate the resistance of white spot syndrome virus (WSSV) in shrimps (Penaeus monodon) to the process of cooking. The cooking was carried out at 1000C six different durations 5, 10, 15, 20, 25 and 30 min. The presence of WSSV was tested by single step and nested polymerase chain reaction (PCR). In the single step PCR, the primers 1s5 & 1a16 and IK1 & IK2 were used. While in the nested PCR, primers IK1 &IK2 – IK3 & IK4 were used for the detection of WSSV. WSSV was detected in the single step PCR with the primers 1s5 and 1a16 and the nested PCR with the primers IK1 and IK2 – IK3 & IK4 from the cooked shrimp samples. The cooked shrimps, which gave positive results for WSSV by PCR, were further confirmed for the viability of WSSV by conducting the bio-inoculation studies. Mortality (100%) was observed within 123 h of intra-muscular post injection (P.I) into the live healthy WSSV-free shrimps (P. monodon). These results show that the WSSV survive the cooking process and even infected cooked shrimp products may pose a transmission risk for WSSV to the native shrimp farming systems.

The relationships between fish assemblages and the amount of bottom horizontal beam exposed at California oil platforms: fish habitat preferences at man-made platforms and (by inference) at natural reefs

Between 1995 and 2002, we surveyed fish assemblages at seven oil platforms off southern and central California using the manned research submersible Delta. At each platform, there is a large horizontal beam situated at or near the sea floor. In some instances, shells and sediment have buried this beam and in other instances it is partially or completely exposed. We found that fish species responded in various ways to the amount of exposure of the beam. A few species, such as blackeye goby (Rhinogobiops nicholsii), greenstriped rockfish (Sebastes elongatus), and pink seaperch (Zalembius rosaceus) tended to avoid the beam. However, many species that typically associate with natural rocky outcrops, such as bocaccio (S. paucispinis), cowcod (S. levis), copper (S. caurinus), greenblotched (S. rosenblatti), pinkrose (S. simulator) and vermilion (S. miniatus) rockfishes, were found most often where the beam was exposed. In particular, a group of species (e.g., bocaccio, cowcod, blue (Sebastes mystinus), and vermilion rockfishes) called here the “sheltering habitat” guild, lived primarily where the beam was exposed and formed a crevice. This work demonstrates that the presence of sheltering sites is important in determining the species composition of man-made reefs and, likely, natural reefs. This research also indicates that adding structures that form sheltering sites in and around decommissioned platforms will likely lead to higher densities of many species typical of hard and complex structure.

White spot viral disease in penaeid shrimp: a review

The white spot viral disease in penaeid shrimp affects the development of the global shrimp industry. This paper reviews the viruses that cause the disease, the transmission of the virus, diagnosis and preventive measures.

Influence of nutrient source on specific dynamic action of Pearl Spot, Etroplus suratensis (Bloch)

The magnitude of apparent specific dynamic action (SDA), the maximum rate of oxygen consumption and the length of time that the rate of oxygen uptake remained elevated above the prefeeding level were measured in the Pearl Spot, Etroplus suratensis, fed isonitrous test diets (D 1 - D 4 ) with varying nutrient sources. Irrespective of the diets, the metabolic rate increased immediately after feeding and reached the maximum within 3 to 4 hours. The source of nutrients in the diet significantly altered the magnitude of SDA. It was maximum (91.76% and 129.56%) for those fed on diets D 2 and D 3 and minimum 46.47% and 50.30% for those fed on diets D 1 and D 4 , respectively.

Effect of type of otolith and preparation technique on age estimation of larval and juvenile spot (Leiostomus xanthurus)

Otoliths of larval and juvenile fish provide a record of age, size, growth, and development (Campana and Neilson, 1985; Thorrold and Hare, 2002). However, determining the time of first increment formation in otoliths (Campana, 2001) and assessing the accuracy (deviation from real age) and precision (repeatability of increment counts from the same otolith) of increment counts are prerequisites for using otoliths to study the life history of fish (Campana and Moksness, 1991). For most fish species, first increment deposition occurs either at hatching, a day after hatching, or after first feeding and yolksac absorption (Jones, 1986; Thorrold and Hare, 2002). Increment deposition before hatching also occurs (Barkmann and Beck, 1976; Radtke and Dean, 1982). If first increment deposition does not occur at hatching, the standard procedure is to add a predetermined number to increment counts to estimate fish age (Campana and Neilson, 1985).

Environmental parameters and incidence of white spot disease in Penaeus monodon (Fab.) farming

An investigation was carried out to monitor management practices and to find out whether there is any relationship with occurrence of deadly white spot disease and environmental parameters. Three semi-intensive and a improved traditional shrimp farms were selected in which mass mortality of shrimp (Penaeus monodon) by white spot disease occurred previously. The farms were situated at two different geographical locations. Two ponds from each farm at random were selected for the study. Out of eight investigated ponds, 6 ponds in three farms were affected by the disease during investigation period. The non-affected ponds had relatively lower stocking density, lightly different management practice and were located at different geographical area. There was no significant variation in water quality parameters among the affected and non-affected ponds. No significant variations were recorded in pond preparation, source of Post Larvae (PL), water and feed management among the affected and non-affected ponds. The observation indicated that pond micro-organisms in a farm may not the only cause of the disease but some external factors also might be responsible for the outbreak of this disease.

Reproductive biology of the blue spot mullet Valamugil seheli (Forskal) from Mangalore Region, southwest coast of India

The blue spot mullet Valamugil seheli spawns once a year between August and February with peak spawning during October - November. Males attain maturity at 250.5 mm and females at 256.5 mm total length. Males outnumbered females in the commercial catches, although the sex-ratio (M:F=1:0.90) in the population showed no significant deviation. The fecundity of this species varied from 108378 to 910350 eggs with an average of 327944. Linear relationships were found between fish length, gonad weight and fecundity; and between fish length, fish weight and ovary weight.

Rapid detection of white spot syndrome virus (WSSV) of Penaeus monodon by latex agglutination test using monoclonal antibodies

Latex beads were sensitized with monoclonal antibodies (MAb) rose against VP28 of WSSV. The optimum concentration of MAb required to sensitize the latex beads was 125 µg/ml. The sensitized latex beads were used to detect WSSV from PCR-positive stomach tissue homogenates obtained from infected shrimp. Stomach tissue homogenates from WSSV-infected shrimp agglutinated the sensitized latex beads within 10 minutes, while uninfected samples did not produce any agglutination, although non-specific agglutinations were observed in some samples. The analytical sensitivity, analytical specificity, diagnostic sensitivity and diagnostic specificity of the (LAT) agglutination test were assessed. The analytical sensitivity of the test was 40 ng of purified WSSV (2 µg/ml). The sensitized latex beads did not agglutinate with normal shrimp tissue or MBV-infected tissue homogenate. The test has a diagnostic sensitivity of 70 and 45%, respectively, compared to single-step and nested PCR. The diagnostic specificity of the test was 82%. This test is a simple and rapid on-farm test which can be used to corroborate clinical signs for the detection of WSSV in grow-out ponds.