scholarly journals Assessment of Longitudinal Gradients in Nematode Communities in the Deep Northern Gulf of Mexico and Concordance with Benthic Taxa

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Jyotsna Sharma ◽  
Jeffrey G. Baguley ◽  
Paul A. Montagna ◽  
Gilbert T. Rowe
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
Distribution Patterns ◽  
Nematode Communities ◽  
Northern Gulf Of Mexico ◽  
The North ◽  
Longitudinal Gradients ◽  
Harpacticoid Copepods ◽  
Significant Difference ◽  
Abundance And Diversity

Meiobenthic nematode assemblages were examined at 16 stations along two transects on the eastern and western boundaries of the deep northern Gulf of Mexico (dNGOM) at depths of 212–3000 m. The highest abundance (297 individuals 10 cm−2) and number of genera (71) occurred at stations near the Mississippi River delta. Number of genera decreased with increasing depth, and showed differences in community composition between the east and west regions. The dominant family, Comesomatidae, was represented by Sabatieria that was present at most shallow stations but absent at greater water depths. A significant difference in nematode feeding morphology was observed between depth groups but not between the two transects at different longitudes. Patterns of nematode community structure are congruent with harpacticoid copepods. Overall, the higher abundance and diversity of nematodes in the north-central Gulf of Mexico is consistent with findings of other benthic taxa and reflects organic material loading from the Mississippi River driving deep sea communities in the Gulf. The east-west gradient in composition of nematode communities suggests that nematode assemblages have well-defined distribution patterns similar to other meiobenthic taxa in the GOM but they are not aligned in the bathymetric zones observed in macrofauna, megafauna and demersal fishes.

Beach vegetation and plant distribution patterns along the northern Gulf of Mexico

1987 ◽  
Vol 15 (2) ◽  
pp. 201-233 ◽  
Author(s):  
M.G. Barbour ◽  
M. Rejmanek ◽  
A. F. Johnson ◽  
B. M. Pavlik
Keyword(s):  
Gulf Of Mexico ◽  
Distribution Patterns ◽  
Plant Distribution ◽  
Northern Gulf Of Mexico ◽  
Beach Vegetation ◽  
Plant Distribution Patterns

The Diversity of Nematode Communities in the Southern North Sea

1974 ◽  
Vol 54 (1) ◽  
pp. 251-255 ◽  
Author(s):  
C. Heip ◽  
W. Decraemer
Keyword(s):  
North Carolina ◽  
North Sea ◽  
Deep Sea ◽  
Benthic Communities ◽  
Nematode Communities ◽  
Diversity Measure ◽  
Southern North Sea ◽  
The North ◽  
Harpacticoid Copepods ◽  
Logarithmic Series

Diversity is one of the most important parameters used in the description of a community; several theories relating diversity to other phenomena as predation, competition and stability have been proposed (Pianka, 1966). As a result of the increasing interest in diversity a number of studies have appeared during recent years, but the meiofauna has until recently been almost completely neglected, rather surprisingly when one considers the importance of this group of organisms in all marine benthic communities. Coull (1972) studied recently the diversity of harpacticoid copepods, with nematodes the major meiobenthic component, along the North Carolina shelf and in the deep sea. Warwick & Buchanan (1970) appear to be the only ones to have studied diversity in nematode communities, using α of the logarithmic series (Fisher, Corbett & Williams, 1943) as a diversity measure. The paucity of data seems primarily to be due to the taxonomic difficulties encountered in studying nematodes.

Validating the occurrence of Caribbean reef sharks, Carcharhinus perezi (Poey), (Chondrichthyes: Carcharhiniformes) in the northern Gulf of Mexico, with a key for sharks of the family Carcharhinidae inhabiting the region

Zootaxa ◽  
2011 ◽  
Vol 2933 (1) ◽  
pp. 65 ◽  
Author(s):  
WILLIAM B. DRIGGERS III ◽  
ERIC R. HOFFMAYER ◽  
EMMA L. HICKERSON ◽  
TIMOTHY L. MARTIN ◽  
CHRISTOPHER T. GLEDHILL
Keyword(s):  
Gulf Of Mexico ◽  
North Atlantic ◽  
Mississippi River ◽  
North Atlantic Ocean ◽  
Shark Species ◽  
Mississippi River Delta ◽  
The Bahamas ◽  
Northern Gulf Of Mexico ◽  
The Family ◽  
Reef Sharks

Among the sharks inhabiting the continental shelf waters of the western North Atlantic Ocean, those within the genus Carcharhinus are the most speciose (Castro 2011). Authoritative sources agree on the presence of twelve species of carcharhinids in the northern Gulf of Mexico; however, they disagree on the presence of a thirteenth species, C. perezi (Poey), in the region (Compagno 1984, Compagno 2002, McEachran & Fechhelm 1998, Castro 2011). While the range of C. perezi is well-documented to extend from the southeastern coast of Florida and the Bahamas to Brazil (Castro 2011), published records of C. perezi occurring in the northern Gulf of Mexico are limited to two sources. In their description of Eulamia springeri, a junior synonym of C. perezi, Bigelow & Schroeder (1944) place the species in the northern Gulf of Mexico based on “a somewhat shrivelled skin with head” from a specimen collected off the west coast of Florida that was reported by the authors to be “probably of this species.” Later, Springer (1960) reported the capture of a single specimen off the Mississippi River Delta in 1947; however, no detail of the capture was provided other than it being listed within a table summarizing shark species collected during exploratory fishing operations.

Maritime Archaeology of the Northern Gulf of Mexico: Archaeology from the Age of Exploration to the Twilight of Sail

2012 ◽  
Author(s):  
Amy Borgens
Keyword(s):  
Gulf Of Mexico ◽  
Maritime Archaeology ◽  
Archaeological Sites ◽  
Public Outreach ◽  
Cultural Resources ◽  
Northern Gulf Of Mexico ◽  
The North ◽  
Age Of Exploration ◽  
Archaeological Work ◽  
Government Involvement

This article describes maritime archaeology in the northern Gulf of Mexico. The first explorations of the Gulf was undertaken in the sixteenth century. The ability to conduct archaeological work in this region is hindered by many environmental factors. The coastal topography is often shallow, necessitating the use of smaller vessels for easy bay and riverine entry. High-visibility dives environments in some areas of the Gulf facilitate discovery and recordation of wreck sites. Government involvement and intervention has led to the protection of some archaeological sites. Remote sensing surveys have identified some of the oldest shipwrecks in the gulf in the North American region. This article summarizes this area's specific shipwreck sites and emphasizes historical events that relate to archaeological discoveries through case studies. Improved data-collection techniques and public outreach can aid in discovering and protecting the Gulf's maritime cultural resources.

scholarly journals Extensive reproductive disruption, ovarian masculinization and aromatase suppression in Atlantic croaker in the northern Gulf of Mexico hypoxic zone

2011 ◽  
Vol 279 (1726) ◽  
pp. 28-38 ◽  
Author(s):  
Peter Thomas ◽  
Md. Saydur Rahman
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
Aromatase Activity ◽  
Northern Gulf Of Mexico ◽  
Hypoxia Exposure ◽  
Hypoxic Zone ◽  
Seasonal Hypoxia ◽  
Reproductive Disruptions ◽  
Reproductive Disruption

The long-term impacts on marine ecosystems of the recent dramatic worldwide increase in the incidence of coastal hypoxia are unknown. Here, we show widespread reproductive disruption in Atlantic croakers collected from hypoxic sites approximately 120 km apart in the extensive northern Gulf of Mexico continental shelf hypoxic zone. Gonadal growth and gamete production were impaired in croakers from hypoxic sites compared with fish from reference normoxic sites east of the Mississippi River Delta. Male germ cells were detected in approximately 19 per cent of croaker ovaries collected in the hypoxic region, but were absent in ovaries from normoxic sites. In addition, the sex ratio was skewed towards males at the hypoxic sites. The masculinization and other reproductive disruptions were associated with declines in neuroendocrine function, as well as ovarian and brain expression of aromatase (the enzyme that converts androgens to oestrogens). A similar incidence of ovarian masculinization and decline in ovarian aromatase expression were observed in croaker after chronic laboratory hypoxia exposure, indicating that ovarian masculinization is a specific hypoxia response and is due to decreased aromatase activity. The results suggest severe reproductive impairment can occur over large coastal regions in marine fish populations exposed to seasonal hypoxia, with potential long-term impacts on population abundance.

scholarly journals Seasonal Mixing and Biological Controls of the Carbonate System in a River-Dominated Continental Shelf Subject to Eutrophication and Hypoxia in the Northern Gulf of Mexico

2021 ◽  
Vol 8 ◽  
Author(s):  
Wei-Jen Huang ◽  
Wei-Jun Cai ◽  
Xinping Hu
Keyword(s):  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Dissolved Inorganic Carbon ◽  
Time Lag ◽  
Distribution Patterns ◽  
Detailed Examination ◽  
Total Alkalinity ◽  
Dominant Factor ◽  
Near Surface ◽  
Northern Gulf Of Mexico

Large rivers export a large amount of dissolved inorganic carbon (DIC) and nutrients to continental shelves; and subsequent river-to-sea mixing, eutrophication, and seasonal hypoxia (dissolved oxygen < 2 mg⋅L–1) can further modify DIC and nutrient distributions and fluxes. However, quantitative studies of seasonal carbonate variations on shelves are still insufficient. We collected total alkalinity (TA), DIC, and NO3– data from nine cruises conducted between 2006 and 2010 on the northern Gulf of Mexico continental shelf, an area strongly influenced by the Mississippi and Atchafalaya Rivers. We applied a three-end-member model (based on salinity and potential alkalinity) to our data to remove the contribution of physical mixing to DIC and nitrate distribution patterns and to derive the net in situ removal of DIC and nitrate (ΔDIC and ΔNO3–, respectively). Systematic analyses demonstrated that the seasonal net DIC removal in the near-surface water was strong during summer and weak in winter. The peak in net DIC production in the near-bottom, subsurface waters of the inner and middle sections of the shelf occurred between July and September; it was coupled, but with a time lag, to the peak in the net DIC removal that occurred in the near-surface waters in June. A similar 2-month delay (i.e., January vs. November) could also be observed between their minima. A detailed examination of the relationship between ΔDIC and ΔNO3– demonstrates that net biological activity was the dominant factor of DIC removal and addition. Other effects, such as air–sea CO2 gas exchange, wetland exports, CaCO3 precipitation, and a regional variation of the Redfield ratio, were relatively minor. We suggest that the delayed coupling between eutrophic surface and hypoxic bottom waters reported here may also be seen in the carbon and nutrient cycles of other nutrient-rich, river-dominated ocean margins worldwide.

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