Development of 15 polymorphic microsatellite markers in the Atlantic tarpon (Megalops atlanticus) for capture-recapture studies

Fifteen polymorphic microsatellite DNA loci for Atlantic tarpon, Megalops atlanticus, were isolated by using PIMA, a polymerase chain reaction‐based technique. The number of alleles at each locus ranged from two to 24 (mean = 7.7) in 65 specimens from Tampa Bay, Florida. Observed and expected heterozygosities ranged from 0.27 to 0.92 (mean = 0.60) and from 0.28 to 0.95 (mean = 0.62), respectively. Genotypes at one locus deviated significantly from Hardy–Weinberg equilibrium. In exact tests for genotypic disequilibrium, there was no evidence of associations between any pair of loci. Overall, loci were well resolved and highly polymorphic, confirming their suitability for DNA fingerprinting applications and other genetic studies.     

Body size and the air-breathing organ of the Atlantic tarpon Megalops atlanticus

The air-breathing organ (ABO) of the Atlantic tarpon is formed by four parallel ridges of alveolar-like respiratory tissue that extend along the length of the physostomous gas bladder. The large and complex surface of each ridge is formed by a cartilage matrix that is completely infiltrated by a thin respiratory epithelium. Comparison of a size series of specimens demonstrates isometric growth of the ABO, and histological and SEM studies show comparable levels of tissue complexity. These findings suggest that air-breathing capacity, which is required for the survival of juvenile fish in their hypoxic nursery habitat, is retained in older tarpon inhabiting more oxygenated marine coastal habitats. The retention of air breathing in adult tarpon may be related to their occasional occurrence in hypoxic waters and their high rates of aerobic metabolism.     

Studies in conservation genetics of tarpon (Megalops atlanticus) — V. Isolation and characterization of microsatellite loci

The tarpon, Megalops atlanticus, supports important recreational fisheries in the Atlantic Ocean, Caribbean Sea and Gulf of Mexico. Declines in segments of these fisheries have prompted questions concerning genetic stock structure in this species. Preparatory to a survey of genetic variation in tarpon, 15 microsatellite markers were isolated. The number of alleles per locus ranged from two to 10 and observed heterozygosity ranged from 0.091 to 0.765, providing potentially useful markers for the detection of within‐ and among‐population genetic variability.     

Allozyme differentiation within and between red drum (Sciaenops ocellatus) from the Gulf of Mexico and Atlantic Ocean

Nine polymorphic nuclear-gene (allozyme) loci were surveyed among 491 red drum ( Sciaenops ocellatus ) sampled in 1988 and 1989 from nearshore localities in the northern Gulf of Mexico (Gulf) and the Atlantic coast of the southeastern United States (Atlantic). Data were combined with those from a previous study to generate a data set of 762 individuals representing 11 sample localities in the Gulf and 175 individuals representing five sample localities in the Atlantic. The combined data set included individuals from the 1986 and 1987 year classes and permitted rigorous testing of both temporal and spatial genetic heterogeneity. Average heterozygosity-per-locus values (estimated using 33 assumed monomorphic loci) were 0·048 (Gulf red drum) and 0·046 (Atlantic red drum). Tests of heterogeneity in allele frequencies between year classes at individual localities and across regions (Gulf and Atlantic) were non-significant. Tests of spatial (geographic) heterogeneity indicated that red drum are weakly subdivided: genetically-differentiated subpopulations occur in the northern Gulf and along the south-eastern Atlantic coast. Genetic data were consistent with the hypothesis that red drum within the Gulf and along the Atlantic coast comprise singie subpopulalions. Genetic differences between Gulf and Atlantic red drum seem likeiy to stem from historical or recent interactions between dispersal and impediments to gene flow.     

Age and growth of tarpon,Megalops atlanticus,larvae in the eastern Gulf of Mexico,with notes on relative abundance and probable spawning areas

Synopsis Leptocephali were collected in June 1981 and July 1989 over the continental shelf and slope of the Florida west coast. Tarpon larvae ranged 5.5–24.4 mm standard length (SL) and were the second most abundant leptocephalus species. Sagittae examined with compound microscopes and scanning electron microscopy had increments that were presumed to be formed daily. Increment counts made using the two microscopic techniques were not significantly different. Estimated ages ranged 2–25 days with a growth rate (± standard error) of 0.92 ± 0.04 mm d^–1 The least squares linear regression equation SL = 2.78 + 0.92 (age in days) best described the relationship between estimated age and length. Adult tarpon appear to undergo a substantial spawning migration from inshore areas frequented during spring and summer to offshore spawning grounds. Spawning occurs during May, June, and July, although the spawning season may be of greater duration.     

Glycosaminoglycan composition of tarpon (Megalops atlanticus) and ladyfish (Elops saurus) leptocephali

Heparan sulphate was found to be the principal glycosaminoglycan (GAG) in tarpon leptocephali, with keratan sulphate also present. The main GAG in ladyfish leptocephali appeared to be a form of chondroitin sulphate (possibly undersulphated).     

Age and growth of Saurenchelys (Nettastomatidae) and Dysomma (Synaphobranchidae) leptocephali in the East China Sea

The otolith microstructures of the leptocephali of Saurenchelys stylura and Dysomma sp., collected in November and December 2000 in the East China Sea, were examined to determine their larval ages and growth rates, and the spawning times of these two species of outer shelf and slope marine eels. Leptocephali ranging in size from 8 to 48 mm total length were examined, and the nettastomatid, S. stylura , and the synaphobranchid, Dysomma sp., had estimated ages that ranged from 16 to 75 days and 17 to 66 days, respectively. The overall growth rate of S. stylura was 0·68 mm day⁻¹( n  = 21), and of Dysomma sp. was 0·44 mm day⁻¹( n  = 22). These growth rates were similar or slightly faster than those observed for anguillid leptocephali in offshore areas of the western Pacific. The backcalculated hatching dates for these two species were from September to November. The otolith increment widths of S. stylura showed an increase before 20 to 30 days that were similar to those in anguillid species, but in Dysomma sp. there were no remarkable increases.     

Distribution and diversity of the Syllidae (Annelida: Polychaeta) from the Mexican Gulf of Mexico and Caribbean

The objective of this study was to contribute to the knowledge of the syllids distributed in the eastern coasts of Mexico (Gulf of Mexico and Caribbean) taking into consideration their composition, distribution and diversity. Sampling was done at 77 stations including 49 in soft bottoms (terrigenous and carbonate sediments), and 28 in hard bottoms (coralline substrates) sampled in nine reef zones included in three reef systems (Veracruz, Campeche and Cozumel). In all 2084 individuals were collected (13.5% in soft sediments and 86.4% in coralline areas). Forty-five species were identified: 31 in soft bottoms and 38 in corals, with 21 species common to both types of environments. In soft bottoms, the highest species richness and diversity were found in the Carbonate Zone, while syllids were uncommon in the Terrigenous Zone. In hard bottoms, the highest density, species richness and diversity values were found in the Veracruz Reef System, followed by the Campeche Bank and Cozumel Island Reef Systems. The dominant species in soft bottoms were Haplosyllis spongicola, Exogone lourei, Typosyllis cornuta and T. papillosus, whereas T. alosae, T. corallicola, T. cornuta and H. spongicola dominated in hard bottoms. The importance and success of the syllids in both soft bottoms and reef environments, particularly in those of the Gulf of Mexico is emphasized.     

An enigmatic heteronemertean from the Gulf of Mexico

Heteroenopleus enigmaticus gen. nov., sp. nov. isdescribed from the northwestern Gulf of Mexico. Itoccurs both in the nearshore Gulf and in high salinityestuarine areas. Body wall musculature conforms tothe general plan of heteronemerteans, i.e. outerlongitudinal, middle circular and inner longitudinalmuscle layers. The head bears a pair of horizontallateral slits, characteristic of the lineids. Theproboscis musculature is of the heteronemerteanpalaeotype with two muscle layers, outer circularand inner longitudinal. Other morphologicalcharacters agree with those of heteronemerteans withone major exception: the proboscis is armed with tworows of structures, herein named parastylets. Thisarmature has no morphological similarity to either themicrovillar proboscideal spines of heteronemerteans orto the stylets of mono- or polystiliferans. A newsubfamily Heteroenopleinae is erected to contain theapomorphic character of an armed proboscis.     

Oncaea frosti,a new species (Copepoda: Poecilostomatoida) from the Liberian coast and the Gulf of Mexico

A new species, Oncaea frosti, is described and compared to O. venusta Philippi and O. venella Farran. The three species are closely related and difficult to distinguish, except for the differences in size of females and males and dorsal dilation of pediger 2 of females of O. frosti.     

Stopover and fat deposition by North American wood-warblers (Parulinae) following spring migration over the Gulf of Mexico

Summary Length of stopover and rate of weight gain (fat deposition) were studied in several species of passerine birds that stopped in southwestern Louisiana along the northern coast of the Gulf of Mexico after a trans-Gulf flight. Fatdepleted birds were more common among the birds that arrived at our study site in southwest Louisiana, though variability characterized our samples. Migrants that landed after encountering opposing winds or rain over the northern Gulf of Mexico were, on average, fatter than migrants that landed when weather was favorable for continued migration. Some of the variation in the energetic condition of arrivals may be explained by the location where migrants initiated crossings. Our simulation of flight over the Gulf of Mexico showed that with following winds a warbler can cross the Gulf of Mexico from Yucatan with fat reserves to spare, and stronger tailwinds make flights from as far south as Honduras energetically permissible. The length of stay after a trans-Gulf flight was related to the extent of fat-depletion upon arrival: lean birds stayed longer than fat migrants. Migrants stopped over for 1–7 days and replenished energy reserves at rates that varied from 0.19 g/d for Hooded Warblers (Wilsonia citrina) to 0.87 g/d for Ovenbirds (Seiurus aurocapillus). Within each species, most individuals gained weight at a rapid rate, though a few individuals lost or maintained weight during their stay.     

Atmospheric trajectories and spring bird migration across the Gulf of Mexico

We examined the relationship between the longitude of peak arrival of trans-Gulf migrants on the northern coast of the Gulf of Mexico in spring and wind trajectories over the Gulf at three different altitudes (500, 1,500, and 2,500 m above ground level). We used data from 10 WSR-88D radars (weather surveillance radar-1988-Doppler) from Brownsville, Texas, to Key West, Florida, to record the time and longitude of peak arrival on the northern Gulf coast for four spring migrations (2001–2004). We used the National Oceanic Atmospheric Administration Air Resources Laboratory HYSPLIT transport and dispersion model at the READY Web site to generate backward, 24-h atmospheric trajectories based on archived atmospheric data for each trans-Gulf flight. The trajectories began at the geographic location where radar indicated the greatest concentrations of arriving migrants. Although the longitude of peak arrival varied, peak densities of most trans-Gulf migrants arrived on the northern coast near longitude 95°W. Regression analyses showed that the relationship between the longitude of peak trans-Gulf arrival and the direction of atmospheric trajectory was significant but weak at the 500-m level, where few migrants occurred, and was insignificant for the 1,500- and 2,500-m altitudes, where migrant densities were greater. We conclude that winds aloft over the Gulf have little influence on the longitude of peak trans-Gulf arrival on the northern coast of the Gulf of Mexico, and we speculate that the arrival pattern may reflect the trans-Gulf migration pathways that evolved during the Last Glacial Maximum.     

Subseafloor microbial communities associated with rapid turbidite deposition in the Gulf of Mexico continental slope (IODP Expedition 308)

The subseafloor microbial communities in the turbidite depositional basins Brazos-Trinity Basin IV (BT Basin) and the Mars-Ursa Basin (Ursa Basin) on the Gulf of Mexico continental slope (IODP holes U1319A, U1320A, U1322B and U1324B) were investigated by PCR-dependent molecular analyses targeted to the small subunit (SSU) rRNA genes, dsrA and mcrA , and hydrogenase activity measurements. Biomass at both basins was very low, with the maximum cell or the SSU rRNA gene copy number <1 × 10⁷ cells mL⁻¹ or copies g⁻¹ sediments, respectively. Hydrogenase activity correlated with biomass estimated by SSU rRNA gene copy number when all data sets were combined. We detected differences in the SSU rRNA gene community structures and SSU rRNA gene copy numbers between the basin-fill and basement sediments in the BT Basin. Examination of microbial communities and hydrogenase activity in the context of geochemical and geophysical parameters and sediment depositional environments revealed that differences in microbial community composition between the basin-fill and basement sediments in the BT Basin were associated with sedimentation regimes tied to the sea-level change. This may also explain the distributions of relatively similar archaeal communities in the Ursa Basin sediments and basement sediments in the BT Basin.     

Morphological and genetic investigations of two western Gulf of Mexico menhadens (Brevoortia spp.)

Gulf menhaden Brevoortia patronus , the main target of a commercial fishing industry in the Gulf of Mexico, and finescale menhaden Brevoortia gunteri , a non-targeted congeneric, have historically been difficult to differentiate. In this study, meristic counts resulted in two of three characteristics that clearly distinguished species, and genetic differences included 1) near fixation for different alleles between species at two of five loci and 2) significantly large divergence ( F _ST) values between species at four loci. Implications for the correct identification of these species and their putative hybrids are discussed.     

Characterization of 13 microsatellite loci for the deep-sea coral, Lophelia pertusa (Linnaeus 1758), from the western North Atlantic Ocean and Gulf of Mexico

A suite of 13 polymorphic tri- and tetranucleotide microsatellite loci were isolated from the ahermatypic deep-sea coral, Lophelia pertusa. Among 51 individuals collected from three disjunct oceanic regions, allelic diversity ranged from six to 38 alleles and averaged 9.1 alleles per locus. Observed heterozygosity ranged from 9.1 to 96.8% and averaged 62.3% in the Gulf of Mexico population. For some loci, amplification success varied among collections, suggesting regional variation in priming site sequences. Four loci showed departures from Hardy-Weinberg equilibrium in certain collections which may reflect nonrandom mating.     

A new genus of Cletopsyllidae (Copepoda,Harpacticoida) from Gulf of Mexico

A new genus and new species of the family Cletopsyllidae Huys & Willems, 1989 from deep-sea sediment in the Gulf of Mexico, are reported and fully described and illustrated. The new genus Pentacletopsyllus (type species: P. montagnisp. n.) can be distinguished from the four known genera of the family by antennule segmentation, length ratio of first and second endopodal segments of P1, and armature pattern on P5 exopod. It also differs from its sister genera by the rostrum being bifid at the tip, third segment of the female antennule having a smooth posterior margin, the baseoendopod of P5 with biarticulate outer setophore bearing basal seta, and female caudal rami without lobate expansion. A revised key to species of the family Cletopsyllidae Huys & Willems, 1989 is provided.     

Free-living dinoflagellates in the southern Gulf of Mexico: Report of data (1979–2002)

The present study is a report of data of planktonic dinoflagellates which includes a list of 252 species, with 10 985 entries in the southern Gulf of Mexico along with information concerning their occurrence. Material for the present study consists of water and net samples obtained during 11 cruises collected at 608 sites between June 1979 and December 2002. Ceratium (47 spp.), Protoperidinium (28 spp.), Dinophysis (26 spp.), Oxytoxum (19 spp.) and Prorocentrum (15 spp.) were the most diverse genera. The most common species found are Ceratium breve, Ceratium contortum, Ceratium furca, Ceratium furca var. eugranum, Ceratium fusus. Ceratium fusus var. seta, Ceratium kofoidii, Ceratium macroceros, Ceratium massiliense, Ceratium pentagonum, Ceratium teres, Ceratium trichoceros, Ceratium tripos, Dinophysis caudata, Ornithocercus magnificus, Podolampas palmipes, Prorocentrum com‐pressum, Prorocentrum gracile, Prorocentrum micans, Protoperidinium divergens and Pyrophacus steinii. Thirteen species are potential toxin producers, among which Karenia brevis was responsible for fish mass mortalities. Other toxic species such as Amphidinium carterae, Dinophysis acuta, Dinophysis caudata, Dinophysis fortii, Dinophysis mitra, Dinophysis rotundata, Dinophysis tripos, Prorocentrum mexicanum, Prorocentrum micans and Prorocentrum minimum were present mostly in net samples. The non‐toxic species Ceratium furca, Pyrodinium bahamense var. bahamense, Scripp‐siella trochoidea and Gonyaulax polygram ma were found in blooms during the summer. Qualitative data show that dinoflagellates occurred mostly during July and August, associated with hydrographic conditions. A checklist of the species and their occurrence are given.     

Marine gastrotrichs from the sand beaches of the northern Gulf of Mexico: species list and distribution

In this meio-faunistic survey along the northern coast of the Gulf of Mexico, gastrotrichs were found in sand collected mostly from beaches on barrier islands. Sediment from Florida and Alabama contained the largest species number. South Texas collecting sites also hosted a very diverse gastrotrich fauna. Paucitubulate Chaetonotida, previously unreported from the area, accounted for about one half of the 45 species encountered. After comparing local specimens also with high resolution videosequences of individuals collected from distant geographic regions, the amphi-Atlantic and/or cosmopolitan distribution of 27 of these species, is confirmed.