The philometrid Philometra carolinensis inhabits the ovaries of the spotted seatrout, Cynoscion nebulosus. A 2-year study in estuaries of South Carolina showed that each year adult female worms were present only during the spawning season of the host and that only sexually mature fish were infected. Overall prevalence was 13.1%. Young-of-the-year fish were uninfected and mature 1-year-old fish were less frequently infected than older fish. Abundance of the philometrid was significantly different in age-1 and -2 spotted seatrout. Prevalence, mean abundance, and intensity peaked during the first 2 months of the host's 4-month spawning season, which then declined abruptly. Occurrence of the philometrid in the fish host was unaffected by water temperature, salinity, and dissolved oxygen. Histological studies revealed that the worms were hematophagous. Worms induced disruption of the ovarian lamellar walls resulting in the interruption of development and the loss of host eggs into the ovarian lumen prior to their maturation. The data show that development of this parasite is linked to the host's reproductive status and suggest that paratenesis plays an important role in the maintenance of the parasite's life cycle.

Across a species' range, the population dynamics of some areas may express spatial synchrony (i.e. they fluctuate with one another), whereas other areas may express no synchrony (they fluctuate independently). The degree of synchrony and spatial extent of synchrony are important considerations when assessing the population as a whole. We examined these aspects in red drum Sciaenops ocellatus along the coast of South Carolina using long-term survey data of juvenile abundance in estuarine areas separated by up to ~200 km. Synchrony of year class strength was detected among areas, but the degree of synchrony declined significantly with distance. By comparison, genetic segregation along the coast was either weak or undetectable (based on allele frequencies at 8 microsatellite loci), although it depended on the year class (2004, 2005 or 2007) of fish that was tested. By standardizing juvenile abundance data across estuaries and survey types, a single, regionwide juvenile time series was generated that covered the 1985-2007 year classes. The juvenile time series correlated significantly with the year class composition of the present-day adult population, which was determined using otoliths collected by a separate survey operating in deeper adult habitats. Future work integrating data across even broader spatial scales would assist in the understanding of large-scale ecological processes that control fluctuations in red drum populations, and would provide useful information for fishery managers.KEY WORDS: Sciaenops ocellatus · Red drum · Synchrony · Population dynamics · Recruitment · Genetics · Microsatellites · South Carolina Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 415: [221][222][223][224][225][226][227][228][229][230][231][232][233][234][235][236] 2010 spatial synchrony or are mobile (e.g. competition or predation) (Ranta et al. 1995, 1997, Hudson & Cattadori 1999, Liebhold et al. 2004. Distinguishing between these factors is difficult and their combined effects may lead to non-intuitive responses (Ranta et al. 1995, Hudson & Cattadori 1999.Large-scale spatial autocorrelations of density-independent environmental conditions have been widely studied as a mechanism that can lead to spatial synchrony. The underlying theory, which was first formulated by Moran in his study of Canadian lynx and hare population cycles (Moran 1953a,b), predicts that local populations with similar density-dependent structures should become synchronized under the influence of a spatially autocorrelated, density-independent factor (Royama 1992, Hudson & Cattadori 1999. This theory is relevant to fisheries because environmental conditions are well known to have major effects on fish population dynamics. In particular, the conditions experienced by the early life stages are critical in determining recruitment success because mortality rates are extremely high. Consequently, any environmental factor that modifies early mortality can have a disproportionate effect on the number...

Abstract.Two new nematode species of Philometra Costa, 1845, P. carolinensis sp. n. and P. cynoscionis sp. n., are described from the spotted seatrout, Cynoscion nebulosus (Cuvier) (Sciaenidae, Perciformes) in estuaries on the Atlantic coast of South Carolina, USA. Philometra carolinensis (males and gravid and subgravid females) parasitic in the host's ovary is most similar to P. lateolabracis (Yamaguti, 1935) in female morphology, but distinctly differs from it in possessing conspicuously short spicules (81-87 µm long) with heavily sclerotized distal parts, the gubernaculum bearing a reflected dorsal barb, and in the length ratio of the gubernaculum and spicules (1:1.23-1.42) in the male. Philometra cynoscionis (only gravid females) found subcutaneously in the host's tissue (lateral to the ascending process of the premaxilla and also posteromedial to the length of each maxilla) is characterized mainly by the presence of cephalic papillae arranged in two circles (8 large papillae in outer circle and 6 small papillae in inner circle), the absence of caudal projections, the body size (length of gravid female 20-33 mm) and the location in the host.During recent investigations into the parasites of fishes in the estuarine systems on the Atlantic coast of South Carolina carried out by the research team of one of the authors (I. de Buron), the spotted seatrout Cynoscion nebulosus (Cuvier) was found to harbour philometrid nematodes located in the ovaries and in the subcutaneous tissue of the head (lateral to the ascending process of each premaxilla, and posteromedial to each maxilla). These proved to represent two previously undescribed species of the genus Philometra Costa, 1845, which are described herein.Cynoscion nebulosus is an important food and sport fish (up to 1 m long and 7 kg weight) inhabiting estuaries of rivers and shallow coastal waters, distributed in the West Atlantic from New York to Florida and in the entire Gulf of Mexico (Froese and Pauly 2005). MATERIALS AND METHODSSpotted seatrout were collected using trammel netting during daytime ebbing tides primarily over mud and oyster shell substrates adjacent to the marsh (<2 m depth). Fish were measured, placed on ice and transported to the laboratory for immediate dissection. Nematodes recovered were washed in physiological saline and then fixed in 70% ethanol or in 4% or 10% formaldehyde solution in physiological saline. Some specimens were fixed and stored in 95% ethanol for subsequent DNA examination. For light microscopy, specimens were cleared with glycerine. Drawings were made with the aid of a Zeiss drawing attachment. After examination, male specimens were mounted in glycerine-jelly as slides, female specimens were maintained in 70% ethanol in vials. Specimens used for scanning electron microscopy (SEM) were transferred to 4% formalin and then postfixed in 1% osmium tetroxide, dehydrated through a graded ethanol series, critical point dried and sputter-coated with gold; they were examined using a JSM-6300 scanning electron microscope at an accele...

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