Life Sciences Commons^™

Thresholds Of Sea-Level Rise Rate And Sea-Level Rise Acceleration Rate In A Vulnerable Coastal Wetland, Wei Wu, Patrick D. Biber, Matthew Bethel

Understanding the Trajectory of Mississippi Coastal Salt Marsh Structure Function, and Processes in the face of Sea Level Rise: Data and Information Repository

Feedbacks among inundation, sediment trapping, and vegetation productivity help maintain coastal wetlands facing sea-level rise (SLR). However, when the SLR rate exceeds a threshold, coastal wetlands can collapse. Understanding the threshold helps address key challenges in ecology—nonlinear response of ecosystems to environmental change, promotes communication between ecologists and resource managers, and facilitates decision-making in climate change policies. We studied the threshold of SLR rate and developed a new threshold of SLR acceleration rate on sustainability of coastal wetlands as SLR is likely to accelerate due to enhanced anthropogenic forces. Deriving these two thresholds depends on the temporal scale, the interaction …

Community Structure And Production Of The Macrobenthos On Four Artificial Reefs In The Mississippi Sound In Relation To Substrate And Profile Type, Patrick Daniel Gillam

Master's Theses

In recent years, the Mississippi Department of Marine Resources (DMR) has made a concerted effort to enhance its coastal fishery resources by creating artificial reefs. Through this effort, 73 nearshore reefs have been created across the MS coast. Different substrate types used to construct MS artificial reefs include oyster shell and cement rubble. Two types of reef architecture used include high profile breakwater and low profile submerged structures. This study compared the benthic biota associated with oyster shell and cement rubble substrates among four artificial reefs representing high and low profile structures in summer 2011. Colonized benthic biota were quantified …

Analyses Of Indices Of Abundance For Important Groundfish Species In The Northern Gulf Of Mexico From 1987-2009, Relative To Shrimp Bycatch; With Age And Growth Of Three Sciaenid Species, Allison Renee Odom

Master's Theses

Bycatch in the shrimp fishery became of particular concern in the 1980s during the peak of shrimp harvest in the northern Gulf of Mexico. Shrimp bycatch is of major importance because the majority of catch in the fishery is not intended target species of commercial shrimp, and most of the additional bycatch is returned to the sea dead or dying, inducing higher rates of mortality. This study was developed to assess the potential ecosystem effects of shrimp harvest on thirty selected species/species groups commonly encountered within the shrimp fishery as bycatch. Delta-lognormal modeling (DLM) was used to determine the relative …

Concentrations And Sources Of Polycyclic Aromatic Hydrocarbons In Surface Coastal Sediments Of The Northern Gulf Of Mexico, Zucheng Wang, Zhanfei Liu, Kehui Xu, Lawrence M. Mayer, Zulin Zhang, Alexander S. Kolker, Wei Wu

Faculty Publications

Background: Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results: PAH concentrations in this region ranged from 100 to 856 ng g(-1), with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then …

Effects Of Hypoxia And 4-Tert-Octylphenol On Gene Expression Profiles Of The Sheepshead Minnow (Cyprinodon Variegatus), Arthur Alan Karels

Dissertations

Hypoxia occurs in estuaries of northern Gulf of Mexico and world-wide, with increasing frequency/severity via eutrophication and anthropogenic influences. Hypoxia inducible factors (HIFs) form transcriptional complex and bind DNA at hypoxia responsive elements (HREs) in promoter regions of genes needed for systemic and cellular adaptation of fish to low dissolved oxygen (hypoxia, DO <2.0 mg/ml). Hypoxia-induced activation of HIF-αs can lead to a cascade of downstream activation, such as erythropoietin (EPO). Return to normal DO levels (normoxia), prolyl hydroxylases (PHDs) are activated to degrade HIF-αs back to baseline. Fish are affected by environmental estrogen mimics, like 4-tert-octylphenol (4tOP), binding estrogen receptor alpha (ERα) at estrogen responsive elements (EREs) and activating genes vitellogenin (VTG). Previous research showed overlap or crosstalk between these two mechanistic pathways. Hypoxia triggers unknown factors regulating ERE-mediated ERα signaling pathway, and stressor combinations could increase/decrease hypoxic or endocrine pathway. Research examined molecular/physiological effects of hypoxia (acute and chronic, moderate and severe) and 4tOP (~60μg/L)on adult male and/or female sheepshead minnow (Cyprinodon variegatus). Three genes identified, cloned, and sequenced (HIF-1α, HIF-2α, and PHD3), plus previously identified genes EPO and VTG, were examined in liver/testes exposed to hypoxia and/or 4tOP for cellular/physiological changes. Endpoints examined included mRNA expression from real-time PCR of HIF-1α, HIF-2α, PHD3, EPO, and VTG using cDNA from total RNA extracts, and microarray analyses of genes expressed during the transition from hypoxia back to normoxia. Phylogenetic analyses confirmed isolation of two HIF-α isofoms (HIF-1α and HIF-2α) and the PHD3 isoform. Significant up-regulation of PHD3 occurred within 10 hrs of chronic hypoxia, and persisted when severe (1.5 mg/L) and declined when moderate (~2.5mg/L). Significant up-regulation of HIF-1α and EPO occurred within 30 minutes to 2 hours of onset of acute severe and very severe (~1.08mg/L) hypoxia. Hypoxia acted similar to an estrogen mimic, with huge up-regulation of VTG gene expression in males, and increased VTG levels (additive effect) when hypoxia was combined with 4tOP. Microarray analyses showed 125 genes with significant transcriptional change, with up- or down-regulation from transitions of: (1) hypoxia (72 hrs) to normoxia (74 hrs) and (2) hypoxia+4tOP (72 hrs) to normoxia+4tOP (74 hrs).

Evidence Of Spawning Capable Tarpon (Megalops Atlanticus) Off The Louisiana Coast, William Stein Iii, Nancy J. Brown-Peterson, James S. Franks, Martin T. O'Connell

Gulf and Caribbean Research

Despite the fact that the tarpon (Megalops atlanticus) is a popular sport fish in the Gulf of Mexico (GOM; Ault et al. 2008), little is known of its spawning behavior. Spawning M. atlanticus have never been documented and fertilized eggs have not been observed in situ (Ault et al. 2008). While it has been suggested that adult M. atlanticus move to deep water off the southwest coast of Florida and into the Yucatan Channel to spawn, the actual locations of spawning grounds remain unknown (Smith 1980, Crabtree et al. 1995, Crabtree et al. 1997). Distribution patterns of larvae …

Relationships Between Particle Properties And Scattering In Coastal Waters Of The Northern Gulf Of Mexico Influenced By The Mississippi River, Bruce Alan Spiering

Dissertations

This study was conducted to determine how the characteristics of an assemblage of suspended particles, including their composition and size affect the relationship between the optical scattering coefficient b (m-1), and the dry mass of the particles in suspension. Knowledge of the scattering to total suspended matter (TSM) ratio, i.e. the mass specific scattering coefficient b* (m2/g), is important because the light detected by optical imaging sensors used for remote sensing is the light that has been scattered by particles back through the water surface. If this ratio is not known or varies within the region of interest, accurate estimates …

Abundance And Distribution Of Two Species Of Squilla (Crustacea: Stomatopoda: Squillidae) In The Northern Gulf Of Mexico, Jennifer L. Wortham

Gulf and Caribbean Research

Stomatopods (mantis shrimps) are predatory benthic crustaceans. Mantis shrimp in the genus Squilla are frequent bycatch animals unintentionally collected in conjunction with the shrimp fishery in the Gulf of Mexico (GOM). Their carcasses are discarded instead of being retained for human consumption, fish meal, or other protein-based food products. The size, depth, salinity, and temperature distributions of these species, as well as their abundance based on gender, were examined to gain biological information that would be necessary if a fishery were to develop in the GOM. I collected samples (n = 2,854) of Squilla empusa and Squilla chydaea in the …

Morphological Characteristics Of Early Life History Stages Of The Blue Crab, Callinectes Sapidus Rathbun, From The Northern Gulf Of Mexico With A Comparison Of Studies From The Atlantic Seaboard, Kenneth Stuck, Harriet Perry, Darcie Graham, Richard W. Heard

Gulf and Caribbean Research

Zoeae, megalopae, and early crab stages of Callinectes sapidus Rathbun, 1896 were described from the northern Gulf of Mexico (nGOM). Observations during this study were based on larvae reared in the laboratory through the early crab stages and on megalopae and early crab stages collected in the wild. Gulf of Mexico data are compared with similar information for the southeast Atlantic coast of the United States. Size and setation of C. sapidus larvae reared from nGOM stocks were different than those in published descriptions of larvae reared from Atlantic populations. Seasonal differences in size were noted in both reared and …

A Multi-Scale Examination Of Stopover Habitat Use By Birds, Jeffrey J. Buler, Frank R. Moore, Stefan Woltmann

Faculty Publications

Most of our understanding of habitat use by migrating land birds comes from studies conducted at single, small spatial scales, which may overemphasize the importance of intrinsic habitat factors, such as food availability, in shaping migrant distributions. We believe that a multi-scale approach is essential to assess the influence of factors that control en route habitat use. We determined the relative importance of eight variables, each operating at a habitat-patch, landscape, or regional spatial scale, in explaining the differential use of hardwood forests by Nearctic-Neotropical land birds during migration. We estimated bird densities through transect surveys at sites near the …

Occurrence Of A Synchronous Hermaphroditic Striped Mullet, Mugil Cephalus, From The Northern Gulf Of Mexico, James S. Franks, Nancy J. Brown-Peterson, Dyan P. Wilson, Ronda J. Russell, Janaith K. Welker

Gulf and Caribbean Research

A synchronous hermaphroditic striped mullet, Mugil cephalus, was captured offshore of Southwest Pass, Louisiana on 6 December 1996 during the commercial roe mullet fishery harvest. The fish measured 412 mm FL, weighed 824 g and was determined to be 4 years old by otolith analysis. Gross examination of the gonads revealed four lobes: right and left ovaries and right and left testis which represents a unique occurrence among hermaphroditic fish. All lobes ended in a common sperm duct/oviduct with the exception of the left ovary which had no oviduct. Both ovaries contained vitellogenic oocytes and both testis had freely …

Cholangioma In A Wild-Caught Sheepshead Minnow (Cyprinodon Variegatus) From The Northern Gulf Of Mexico, Lee A. Courtney

Gulf and Caribbean Research

A single case of ac holangioma occurred in the liver of a wild-caught sheepshead minnow (Cyprinodon variegatus). This is the first biliary neoplasm and second case of a hepatic neoplasm reported from a wild-caught specimen of this species. The findings further demonstrate the susceptibility of the sheepshead minnow to neoplasm development and add support to its selection as a subject for field monitoring of carcinogenic exposure.

Trophic Structure Of Macrobenthic Communities In Northern Gulf Of Mexico Estuaries, Gary R. Gaston, Steven S. Brown, Chet F. Rakocinski, Richard W. Heard, J. Kevin Summers

Gulf and Caribbean Research

Trophic structure of estuarine benthic communities in the northern Gulf of Mexico was characterized according to the functional roles and geographic distributions of the macrobenthos. Macrobenthic organisms collected during two years of study were assigned to trophic groups to assess the relative utilization of detritus and other resources. Three groups of detritivores (surface-deposit feeders, subsurface-deposit feeders, and filter feeders) were numerically dominant among the benthos, each of which accounted for 25-30% of total abundance across regions. Carnivorous macrobenthos also comprised an appreciable portion (12%), while omnivores (<3%) and other groups (<4%) were poorly represented. Dominance by detritivores is consistent with current concepts regarding the role of macrobenthos in processing detritus of Gulf of Mexico estuaries.

Haustorius Jayneae, A New Species Of Haustoriid Amphipod From The Northern Gulf Of Mexico, With Notes On Its Ecology At Panama City Beach, Florida U.S.A., John M. Foster, Sara E. Lecroy

Gulf and Caribbean Research

A new species of sand-burrowing amphipod, Haustorius jayneae, is described from the swash zone and shallow subtidal sands along the north Florida and Mississippi Gulf coasts. It is most similar to H. canadensis from the American Atlantic coast, differing primarily in the presence of a distinct anterodistal spinous lobe on pereopod 6, article 5; a longer row of distal marginal spines on pereopod 7, article 4; and fewer proximal spines on the peduncle of uropod 1. A revised key to the known species of Haustorius is included and information on the ecology of H. jayneae n. sp. at Panama …

An Illustrated Key To The Chaetognatha Of The Northern Gulf Of Mexico With Notes On Their Distribution, Jerry A. Mclelland

Gulf and Caribbean Research

A key is provided to facilitate the identification of 24 species in nine genera of Chaetognatha occurring in the northem Gulf of Mexico. Included are the deep-water species, Eukrohnia proboscidea, E. calliops, Mesosagitta sibogae, and Sagitta megalophthalma, all recent additions to the known fauna of the region. Meristic data, brief descriptions, ecological notes, Gulf of Mexico records, and illustrations are also presented.

Records Of Deep-Water Chaetognaths From The Northern Gulf Of Mexico, Jerry A. Mclelland, Harriet M. Perry

Gulf and Caribbean Research

Fourteen species of deep-water Chaetognatha were present in plankton samples collected between 200 and 677 m at five stations along the continental slope of the northem Gulf of Mexico. Samples were taken in conjunction with the MARFlN Geryon cruises of 1987 and 1988. New Gulf of Mexico records resulting from this study were Eukrohnia calliops, Eukrohnia proboscidea, Mesosagitta sibogae, and Sagitta megalophthalma. Other deepwater species present were Eukrohnia fowleri, E. bathypelagica, E. bathyantarctica, Caecosagitta macrocephala, Mesosagitta decipiens, M. minima, Solidosagitta planctonis, Krohnitta subtilis, Flaccisagitta hexaptera, and F. lyra …

Acanthohaustorius Uncinus, A New Species Of Sand-Burrowing Amphipod From The Northern Gulf Of Mexico, With Notes On Its Ecology (Haustoriidae: Haustoriinae), John M. Foster

Gulf and Caribbean Research

A new species of sand-burrowing amphipod, Acanthohaustorius uncinus, is described from vegetated and unvegetated estuarine sands from St. Andrew Bay, Florida and East Ship Island, Mississippi. The genus Acanthohaustorius has been informally recorded from St. Andrew Bay, but this species is now formally described from the Gulf of Mexico. A. uncinus n. sp. is most similar to A. millsi of the Open American Atlantic coast. It differs from A. millsi in the presence of a dorsally directed, hooked spine on the peduncle of uropod 1 and the totally cleft telson lobes. Information on the ecology of A. uncinus n. …

An Unusually Small Egg-Carrying Callinectes Sapidus In The Northern Gulf Of Mexico, With Comments On The Barnacle Loxothylacus Texanus, Robin M. Overstreet, Harriet M. Perry, Gerald Adkins

Gulf and Caribbean Research

This communication reports the smallest verified egg-carrying specimen of Callinectes sapidus. With a carapace 20 mm long by 47 mm wide, the female measures considerably less than most other mature individuals, but about the same as an average-sized individual infected with an adult specimen of the rhizocephalan Loxothylacus texanus.

Notes On The Northern Gulf Of Mexico Occurrence Of Sagitta Friderici Ritter-Zahony (Chaetognatha), Jerry A. Mclelland

Gulf and Caribbean Research

The neritic chaetognath Sagitta friderici Ritter-Zahony, 1911 was identified in plankton samples from the northern Gulf of Mexico in June 1974. Specimens analyzed from two groups of adults ranged from 6 to 13.7 mm long. Meristic values did not appear to be a function of body length except for individuals in the 12.4 to 13.7 mm range that had larger numbers of hooks and teeth.

Adults of Sagitta friderici and the closely related S. tenuis Conant, 1896 were compared and found to be distinguishable chiefly by (1) the number of ova per unit length of the ovary, and (2) the …

Lepidactylus Triarticulatus N. Sp., A New Haustoriid Amphipod From The Northern Gulf Of Mexico, Philip B. Robertson, Charles R. Shelton

Gulf and Caribbean Research

A new haustoriid amphipod, Lepidactylus triarticulatus n. sp., from the northern Gulf of Mexico is described and illustrated. The known range is from northern Padre Island, Texas, to Grand Isle, Louisiana. The species is ecologically plastic. On surf-exposed sandy beaches it is most abundant at the highest intertidal levels, but in fine-grained sands of wave-sheltered localities it occurs throughout the intertidal region into shallow subtidal depths. In central Texas bays it has been collected subtidally at salinities as low as 10 ppt. There are differences in morphological details of peraeopod 7 between the intertidal and subtidal populations which we regard …

Notes On The Genus Probythinella Thiele, 1928 (Gastropoda: Hydrobiidae) In The Coastal Waters Of The Northern Gulf Of Mexico And The Taxonomic Status Of Vioscalba Louisianae Morrison, 1965, Richard W. Heard

Gulf and Caribbean Research

The gastropod genus Probythinella Thiele, 1928, is considered a senior synonym of Vioscalba Morrison, 1965. Probythinella louisianae (Morrison, 1965) n. comb. tentatively is recognized as a valid species distinct from the closely related P. lacustris (Baker, 1928) and P. protera Pilsbry, 1953. The eastern range of P. louisianae is extended to Mobile Bay, Alabama. Limited observations on the habitat and reproduction of P. louisianae are reported.