The Effects of Season and Proximity to Fringing Mangroves on Seagrass-Associated Fish Communities in Charlotte Harbor, Florida

Little has been published on habitat use by fishes in Charlotte Harbor, one of Florida\u27s largest-and still relatively pristine-estuaries. Multivariate analyses of data from 21.3-m-seine samples (1996-2000) were used to examine spatiotemporal patterns of seagrass habitat use by Charlotte Harbor fishes. Two habitats (mangrove-associated seagrass shorelines and offshore seagrass flats) were examined. Throughout the year, the mangrove-seagrass habitat was distinguished by Menidia spp., Mugil gyrans, Eucinostomus harengulus, and Floridichthys carpio, and the offshore seagrass flats habitat was distinguished by Bairdiella chrysoura, Orthopristis chrysoptera, and Cynoscion nebulosus. The dry season (Dec.-May) was distinguished by Lagodon rhomboides, Leiostomus xanthurus, and O. chrysoptera in both habitats and by Mugil cephalus in the mangrove-seagrass habitat. The wet season (June-Nov.) was distinguished by Lucania parva, F. carpio, and Fundulus grandis in the mangrove-seagrass habitat and by Eucinostomus gula, Microgobius gulosus, C. nebulosus, and E. harengulus in the offshore seagrass flats habitat. Eucinostomus spp., Anchoa mitchilli, and Strongylura notata were abundant in both habitats during the wet season. In general, many species were collected in both habitats and were widely distributed in the estuary. Various combinations of four environmental variables (i.e., water temperature, salinity, dissolved oxygen, water depth) and their coefficients of variation were well correlated with the biotic community patterns. These results show that different fish communities use different seagrass habitats in Charlotte Harbor, depending on the season and the proximity of the seagrasses to fringing mangroves

Habitat Use by Juvenile Gag, Mycteroperca microlepis (Pisces: Serranidae), in Subtropical Charlotte Harbor, Florida (USA)

Estuaries play a key role in the juvenile stage of gag (Myeteroperca microlepis). The use of estuarine habitats by juvenlle gag has been examined in temperate estuaries, which are at the northern limits of the range of this species, but the importance of subtropical estuaries during the early life history of this species has not been studied extensively. Gag were collected in subtropical Charlotte Harbor, Florida, during routine monthiy sampling from January 1996 to Decemher 2002. Juvenlle gag were collected using a 21.3-m seine, a 183-m haul seine, and a 183-m purse seine. A total of 738 individuals ranging from 30 to 489 mm standard length (SL) were collected in 4,480 samples. Most gag (96%) were probably young-of-the-year (\u3c 288 mm SL). The majority of juveniles were collected in polyhaline Gasparilla and Pine Island sounds from April to December, with a few larger individuals captured year-round. The observed period of gag settlement was similar to thet reported in other subtropical and temperate estuaries, but gag in Charlotte Harbor remained in the estuary longer and egressed at a larger size than did gag in other estuaries. Relative abundance of juvenile gag within Charlotte Harbor was greatest on shallow seagrass shoals but was also high along flinging mangrove shorelines, which is a habitat not previously reported for gag

Fishes of the Charlotte Harbor Estuarine System, Florida

To date, 255 fish species in 95 families have been reliably reported from the Charlotte Harbor estuarine system in southwest Florida. The species list was compiled from recent fishery-independent collections, a review of reports and peer-reviewed literature, and examination of cataloged specimens at the Florida Museum of Natural History. Thirty-nine species are new records for this estuarine system. Many of the newly documented species are common on the west Florida continental shelf and associated inshore habitats. Twenty-two previously reported species were not included in the species list presented herein on the basis of more recent research, doubtful original identifications, or questionable locality data

Long-term site fidelity of endangered smalltooth sawfish (Pristis pectinata) from different mothers

Understanding how endangered species use nursery habitats is vital for recovery planning. Research on the smalltooth sawfish (Pristis pectinata) has shown that areas of estuarine nurseries, called hotspots, are used consistently. The objectives of our study were 1) to determine whether 10 young-of-the-year smalltooth sawfish in an artificial, non-main-stem portion (i.e., a seawall canal system) of a hotspot were descended from one or different mothers and 2) to document long-term habitat use by these individuals. At least 4 mothers contributed to the group, which comprised siblings, half-siblings, and unrelated individuals. Young sawfish exhibited site fidelity to their capture location, spending 61% of their time there. Continuous residency lasted as long as 86 days, but these fish made small-scale diel

Parasite Component Community of Smalltooth Sawfish Off Florida: Diversity, Conservation Concerns, and Research Applications

Compared with that of other charismatic elasmobranchs, the component community of metazoan parasites infecting endangered smalltooth sawfish Pristis pectinata is exceedingly poorly characterized: adults of Dermophthirioides pristidis and Neoheterocotyle inpristi (ectoparasitic flatworms of skin and gill, respectively) were the only confirmed parasites prior to the description, based on specimens reported herein, of Mycteronastes caalusi. Our opportune and directed parasitological examinations of 290 smalltooth sawfish (277 live inspections; 13 necropsies; 671 to 2640 mm stretch total length) in south Florida coastal waters revealed at least 8 species of Platyhelminthes, 9 of Arthropoda, 4 of Annelida, and 1 of Nematoda. This collection includes representatives of an undescribed species of Aporocotylidae (Digenea) and myriad new host records, considerably updating and advancing our understanding of smalltooth sawfish symbionts. We also confirm that D. pristidis and N. inpristi are extant and propose D. pristidis as a reliable biological tag. Some of these parasites are evidently highly host-specific and so vulnerable to extinction

Data from: Facultative parthenogenesis in a critically endangered wild vertebrate

Facultative parthenogenesis — the ability of sexually reproducing species to sometimes produce offspring asexually — is known from a wide range of ordinarily sexually reproducing vertebrates in captivity, including some birds, reptiles and sharks 1, 2 and 3. Despite this, free-living parthenogens have never been observed in any of these taxa in the wild, although two free-living snakes were recently discovered each gestating a single parthenogen — one copperhead (Agkistrodon contortrix) and one cottonmouth (Agkistrodon piscivorus). Vertebrate parthenogens are characterized as being of the homogametic sex (e.g., females in sharks, males in birds) and by having elevated homozygosity compared to their mother 1, 2 and 3, which may reduce their viability. Although it is unknown if either of the parthenogenetic snakes would have been carried to term or survived in the wild, facultative parthenogenesis might have adaptive significance. If this is true, it is reasonable to hypothesize that parthenogenesis would be found most often at low population density, when females risk reproductive failure because finding mates is difficult. Here, we document the first examples of viable parthenogens living in a normally sexually reproducing wild vertebrate, the smalltooth sawfish (Pristis pectinata). We also provide a simple approach to screen any microsatellite DNA database for parthenogens, which will enable hypothesis-driven research on the significance of vertebrate parthenogenesis in the wild

Abiotic affinities and spatiotemporal distribution of the endangered smalltooth sawfish, Pristis pectinata, in a south-western Florida nursery

Understanding how endangered marine species rely on coastal habitats is vital for population recovery planning. The smalltooth sawfish (Pristis pectinata) is one of several critically endangered sawfishes worldwide known to use estuaries and rivers during their early life history. In a Florida estuary designated as critical habitat by the USA government, juveniles were monitored to characterise seasonality, recruitment, and habitat use. Stretched total length ranged from 671 to 2172 mm (n = 137, mean = 1248 mm). Sawfish were captured year round. Captures of neonates with embryonic rostral sheaths allowed refinement of the size at birth (671–812 mm) and confirmed a protracted timing of parturition (November–July), which peaked between April and May. Although sampling occurred throughout the estuary, five locations had the greatest catch rates. Most juvenile sawfish had an affinity for water 30°C, dissolved oxygen >6 mg L–1, and salinity between 18 and 30. Greater catch rates for sawfish >1 year old were associated with shoreline habitats with overhanging vegetation such as mangroves. These results detail habitat use within a recognised nursery that can be used for conservation of the first endangered marine fish species in the USA

Movements of juvenile endangered smalltooth sawfish, Pristis pectinata, in an estuarine river system: use of non-main-stem river habitats and lagged responses to freshwater inflow-related changes

The smalltooth sawfish (Pristis pectinata) is one of seven critically endangered sawfishes worldwide that little is known about beyond their presence in estuaries and rivers primarily during early life history. Movements of 24 juvenile P. pectinata (<3 years old) were monitored over more than 2 years using acoustic tags and an array of 33 acoustic receivers. The receivers were distributed in both main-stem river habitats, which are known to be used by this species, and non-main-stem habitats (i.e., natural mangrove-lined creeks, seminatural creeks, seawall-lined canals) of the highly altered, flow-managed tidal Caloosahatchee River, Florida to determine (1) the extent of non-main-stem habitat use and (2) responses to freshwater inflow-related changes by P. pectinata. Twenty P. pectinata used non-main-stem habitats, and 11 used these habitats more than 10 % of the time, which has implications for management within the federally protected nursery area. The daily activity space of P. pectinata was 0.7 km of river distance, which is similar to that of other demersal ray species. There was little evidence that P. pectinata left the river and returned; they remained in the nursery under a wide range of environmental conditions. The distribution of all P. pectinata combined was significantly related to 90-day lagged salinity; sawfish moved upriver as salinity increased. Salinity patterns within the river had a greater effect on the distribution (mean river position) of <1-year-old P. pectinata (90-day lagged salinity) than on that of older individuals (120-day lagged salinity). These results provide further evidence of the importance of this system as a nursery and provide specific habitat use patterns that will be useful in the development of management strategies for sawfishes and their habitats

Preservation Effects on Stable Isotope Values of Archived Elasmobranch Fin Tissue: Comparisons between Frozen and Ethanol-Stored Samples

Elasmobranch fin tissue has been sampled and archived for decades to support genetics research. However, these collections have the potential to provide additional information on the trophic ecology of and habitat use by elasmobranch species. The use of fin tissue is especially attractive considering the threatened status of many elasmobranchs and the call for limiting mortalities. Yet, the use of fin samples for stable isotope analysis requires either that (1) storage methods do not alter tissue isotope values or (2) any alterations in isotope composition that occur during storage are predictable. In this study, paired fin tissues sampled from Smalltooth Sawfish Pristis pectinata and cownose rays Rhinoptera spp. were stored frozen and in ethanol and were subsequently analyzed for carbon (δ13C) and nitrogen (δ15N) isotope ratios. Fin δ13C and δ15N values were highly correlated between treatments for both taxa (r2 ≥ 0.80). For Smalltooth Sawfish, ethanol storage significantly increased fin δ13C values by 0.5 ± 0.1‰ (mean ± SE) and decreased fin δ15N values by 0.1 ± 0.1‰ relative to frozen samples; differences were similar for cownose rays (δ13C: 0.2 ± 0.2‰; δ15N: 0.2 ± 0.1‰) but were not significant. A range of approximately 3‰ for δ13C between treatments could have effects on data interpretation, suggesting the use of regressions for ethanol correction of δ13C values, although trends were comparable between frozen and ethanol-preserved samples without correction. Given the low variability in δ15N values, a correction is not warranted. For endangered species such as the Smalltooth Sawfish, stable isotope analysis of ethanol-archived fin samples can provide important information regarding habitat use and trophic ecology, with potential significance for conservation and management strategies. The general uniformity in isotope ratio shifts observed for archived samples between the two taxa suggests that these findings can be generalized across elasmobranch species