Settlement of the Acorn Barnacle Balanus From Mobile Bay and Weeks Bay, Alabama

Barnacle cyprids and metamorphosed settlers were collected using glass slides as artificial substrates at six sites in the Mobile Bay area. Three sites were located in Weeks Bay, Alabama, where the highest settlement concentration occurred near the entrance to Mobile Bay. Two sites in the north end of Weeks Bay near the Fish River had very reduced settlement. The remaining three locations were on the north shore of Dauphin Island, Alabama. Settlement at Dauphin Island was most abundant at the deeper of two sites at the Dauphin Island Sea Lab boat dock, possibly because the substrates were exposed to less wave action. The other two sites at Dauphin Island were shallow and relatively unsettled when compared with the deep site. Adult barnacles recovered from the Weeks Bay and Dauphin Island locations include Balanus eburneus, B. venustus, B. improvisus, and B. subalbidus. Our data indicate two primary settlement periods for these species, late winter to spring and late summer to fall, with the highest settlement occurring in Feb. and March

Ciliated Protozoan Colonization of Substrates From Weeks Bay, Alabama

Ciliated protozoan colonization of artificial substrates was examined during a 12-mo period from Jan. to Dec. 2001 in Weeks Bay, Alabama. Artificial substrates (glass slides) were suspended in the water at three locations in the Bay for a period of I wk/mo, and the population density of the stalked peritrich Vorticella was determined. Environmental data collected during the colonization period were compared with the population results. There was a positive correlation between colonization and water temperature at two sites and between phosphate and colonization at one site. Additionally, a negative correlation was determined between colonization and dissolved oxygen at two sites, between colonization and nitrate at one site, and between colonization and pH at one site. The protozoan assemblage varied from month to month, although the overall dominance of Vorticella was maintained. Although the size of the population of Vorticella is likely influenced by a number of different variables, we believe that temperature and bacterial abundance are the likely controlling factors

Bacterial Communities on the Northern Gulf of Mexico Continental Shelf are Influenced by Sediment Characteristics Affected by the Mississippi River

Benthic bacteria in the Gulf of Mexico serve the base of the sediment food chain as a food source for various marine organisms. In this paper, we analyzed the bacterial community and sediment characteristics from 14 sediment samples collected along the continental shelf of the northern Gulf of Mexico. Using the bacterial community to assess relationships among our sites, the data revealed groupings of sites that correlated to the sediment characteristics, generally grouped as western sites in Louisiana near the outflow of the Mississippi River and eastern Florida sites more distant from the outflow. Cluster analysis and multidimensional scaling demonstrated significant groupings of Louisiana vs Florida bacterial communities, and distance-based redundancy analysis related these groupings to sediment characteristics. Given the directions of currents around the Mississippi River, our data suggested that the outflow of the river is a major factor affecting the benthic bacterial community in the northern Gulf of Mexico

Variations in the Ventral Ciliature of the Crustacean Symbiont Hyalophysa (Ciliophora, Apostomatida) from Mobile Bay and Dauphin Island, Alabama

Apostome ciliates are symbiotic organisms whose life cycles are complex and involve specific feeding, divisional, migratory, and phoretic stages. In this study we examined apostome trophonts (the diagnostic stage) from a variety of crustacean hosts in the Mobile Bay and Dauphin Island, Alabama, area. The hosts were grass shrimp (Palaemonetes pugio and P. paludosus), striped hermit crab (Clibanarius vittatus), blue crab (Callinectes sapidus), and pink shrimp (Farfantepenaeus (=Penaeus) duorarum). A number of similar but distinct morphotypes of apostomes were present, those corresponding to descriptions of species of Hyalophysa as well as variant forms. The morphotypes observed in this study had the following characteristics: variations in the formation of the anterior ventral field of kinetosomes from falciform field 9; variations in the degree to which ciliary row 1 (kinety 1) was separated into 2 segments; and variations in the development of kinety a. A record of the variant morphotypes that do not correspond exactly to an established species should prove useful to biologists attempting to identify apostomes from crustacean molts. We choose not to name the variant forms as new species because they exist as different morphotypes within a population of cells, because some of these types occur in low frequency, and because one of the variant forms changes from one morphotype to another

Variations in the Ventral Ciliature of the Crustacean Symbiont Hyalophysa (Ciliophora, Apostomatida) from Mobile Bay and Dauphin Island, Alabama

Apostome ciliates are symbiotic organisms whose life cycles are complex and involve specific feeding, divisional, migratory, and phoretic stages. In this study we examined apostome trophonts (the diagnostic stage) from a variety of crustacean hosts in the Mobile Bay and Dauphin Island, Alabama, area. The hosts were grass shrimp (Palaemonetes pugio and P. paludosus), striped hermit crab (Clibanarius vittatus), blue crab (Callinectes sapidus), and pink shrimp (Farfantepenaeus (=Penaeus) duorarum). A number of similar but distinct morphotypes of apostomes were present, those corresponding to descriptions of species of Hyalophysa as well as variant forms. The morphotypes observed in this study had the following characteristics: variations in the formation of the anterior ventral field of kinetosomes from falciform field 9; variations in the degree to which ciliary row 1 (kinety 1) was separated into 2 segments; and variations in the development of kinety a. A record of the variant morphotypes that do not correspond exactly to an established species should prove useful to biologists attempting to identify apostomes from crustacean molts. We choose not to name the variant forms as new species because they exist as different morphotypes within a population of cells, because some of these types occur in low frequency, and because one of the variant forms changes from one morphotype to another

Kinorhynch diversity in the southern Gulf of Mexico and a description of Dracoderes chaac sp. nov.

Sediment collections from the southern Gulf of Mexico between the Texas—Mexico border and the Yucatán Peninsula have resulted in many new kinorhynch species distribution records and the finding and taxonomic description of a new species, Dracoderes chaac sp. nov. This study focused on the non—echinoderid members of the Phylum Kinorhyncha, many of which are rare or restricted to only a few locations. A total of 136 specimens were identified from 24 sediment stations, distributed among the following species: Antygomonas gwenae, Campyloderes vanhoeffeni, Centroderes readae, Condyloderes flosfimbriatus, Co. rohalorum, Cristaphyes panamensis, Dracoderes chaac sp. nov., Leiocanthus corrugatus, L. langi, L. quinquenudus, L. satanicus, Pycnophyes alexandroi, Semnoderes lusca, and Sphenoderes aspidochelone. Additional undescribed species in the genera Leiocanthus, Mixtophyes, and Paracentrophyes were recovered. Statistical analysis of the stations revealed a grouping of locations where the majority of the pycnophyid species were recovered. Some species (e.g., Ca. vanhoeffeni, S. aspidochelone) had an extensive distribution, while others were recorded from one or few locations only (e.g., A. gwenae, Co. rohalorum). Most of the species were reported from earlier collections in the northern Gulf of Mexico on the U.S. continental shelf, between 700–1100 km away

Colonization of Artificial Substrates at Dauphin Island, Alabama: A Comparison of Balanus (Cirripedia), Membranipora tenuis (Bryozoa), and Conopeum tenuissimum (Bryozoa) Settlement in 1999-2000 and 2010-12

Glass slides were used as artificial substrates to collect settling bryozoan and barnacle larvae during two collection periods, in 1999–2000 and 2010–12. This study follows up a previous report of Balanus settlement in Mobile Bay and now includes two bryozoan species. Slides were immersed at the Dauphin Island Sea Lab (Alabama) for 1 wk each month for 17–18 mo in each study, and then collected for staining and counting. The bryozoans Conopeum tenuissimum and Membranipora tenuis were both present in 1999–2000, though in 2010–12 C. tenuissimum was rarer and only six organisms were observed. In general the bryozoan colonization period extended throughout the spring, summer, and fall, with peak settlement in May–Aug. Barnacle cyprids and metamorphed stages colonized the substrates in July–Sept. and Feb.– March in 1999–2000, but in 2010–12 they were present in the summer and fall months and did not have a Feb.–March settlement. Colonization by both bryozoans and barnacles correlated statistically with temperature, and M. tenuis correlated negatively with salinity as its colonization density increased following the decreased salinity in the spring. In 1999–2000 only M. tenuis correlated with temperature. This study reports settlement periods for these invertebrates in Alabama and provides new data for colonization studies in Mobile Bay. Additionally, we document the successful colonization of substrates by these invertebrates immediately following the Deepwater Horizon oil spill

Histochemical Study of the Progenetic Trematode Alloglossidium renale

A histochemical study of the progenetic trematode Alloglossidium renale has demonstrated the absence of any secreted material between the adult worm and the host (freshwater shrimp) antennal gland tubules. Host tissue is affected only by the compression, abrasion, and ingestion by the parasite, and host tubule cells near the worm have the same staining patterns as those distant from the parasite. The trematode sometimes dies within the host, leaving a necrotic mass whose histochemical staining differs significantly from the living organism. In the necrotic mass, the only recognizable features were the ova and the vitellarium, which atrophied and resulted in tyrosine-positive staining within the mass. A melanin reaction was not observed in the host using a specialized ferro-ferricyanide stain. The only apparent host response to infection was a layer of damaged squamous host cells adhering to the necrotic worm. The results confirm benign host-parasite effects and a highly evolved relationship between the host and parasite, perhaps bordering on commensalism

A Multi-Year Survey of Meiofaunal Abundance From the Northern Gulf of Mexico Continental Shelf and Slope

This 3-yr (2007–09) survey documented meiofauna abundance across the northern Gulf of Mexico on the continental shelf and slope from south Texas to south Florida. Sediment samples were collected from depths ranging from 29 to 509 m (average = 132 m) on the National Oceanic and Atmospheric Admistration ship Gordon Gunter during the annual fall small pelagics fish-sampling cruise. A total of 259 sediment samples from 99 ShipekH grabs were analyzed. Meiofauna were isolated from the sediment by sieving (63-mm sieve) and concentrating the organisms via LudoxH centrifugation. Each year the two dominant animal groups were nematodes and copepods, followed by polychaetes, nauplii, kinorhynchs, priapulid loricate larvae, tardigrades, and Acari. Spearman correlations indicated that abundances of nematodes, copepods, polychaetes, and nauplii were positively related, and that all meiofauna groups decreased in abundance with increasing longitude (farther west). Abiotic variables such as salinity, temperature, and depth did not correlate with any meiofauna group. Distribution maps of the animals indicated a clear geographic trend that was supported statistically, in that the animal groups were more concentrated in Florida samples rather than the central and western continental shelf