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1.
Nancy J. Brown-Peterson C. Steve Manning Nancy D. Denslow Marius Brouwer 《Aquatic Sciences - Research Across Boundaries》2011,73(1):127-141
Identification of organisms able to act as biological indicators of hypoxia exposure is important given the increasing frequency
of hypoxic events worldwide. Grass shrimp, Palaemonetes pugio, are ubiquitous estuarine residents in the southeastern US, where they commonly experience cyclic hypoxia. We hypothesized
that reproductive and gene expression patterns of grass shrimp in cyclic hypoxic field sites relative to normoxic sites would
be similar to previous results from cyclic hypoxia laboratory experiments showing differential up- and down-regulation of
hypoxia-responsive genes. There were few differences in gene expression of indigenous shrimp collected during summer from
two Gulf of Mexico estuarine systems [East Bay, FL (EB) and Weeks Bay, AL (WB)], although down-regulation of the gene coding
for vitellogenin-1 corresponded with a decreased relative fecundity and fewer ovigerous females at cyclic hypoxic field sites,
suggesting an overall impact on reproduction. The gene expression profiles of grass shrimp caged for 7 days in field sites
differed by estuary, but few hypoxia-responsive genes identified in laboratory studies were differentially expressed in field
shrimp. Overall, genes coding for protein synthesis, protein degradation, carbohydrate and lipid metabolism and electron transport
were mostly up-regulated in EB caged shrimp but generally down-regulated in WB caged shrimp and laboratory shrimp. Thus, caged
grass shrimp from different bay systems exhibited profoundly different gene expression profiles. Such profiles may serve as
sensitive bioindicators of differences in water quality, habitat quality or food resources among estuaries but are not effective
as indicators of hypoxia exposure. 相似文献
2.
3.
Predicting summer hypoxia in the northern Gulf of Mexico: redux 总被引：1，自引：0，他引：1
We report on the evolution and accuracy of a model used to predict the mid-summer area of hypoxia (oxygen ≤2 mg l(-1)) in the northern Gulf of Mexico, use it to test for impacts from the Deepwater Horizon oil spill (2010), and estimate the N loading that would meet a management goal. The prediction since 2000 were 100%±6% (μ±1 SE) of the actual value. The predicted in 2010 was 99% of that actual value, suggesting that the net effect of the 2010 oil spill on the hypoxic zone size was negligible. A tropical storm, however, may have reduced the potential size of the hypoxic zone. Lowering the May nitrogen load to about 70,000 mton N nitrate+nitrite would bring the model's predicted hypoxic zone size down to the management goal of 5000 km(2) and restore hypoxic waters to normoxic conditions. 相似文献
4.
Since increased ventilation is known to be a common strategy used by aquatic animals to cope with hypoxia, we tested in present study the hypothesis that hypoxia can promote the bioaccumulation of naphthalene, a representative polycyclic aromatic hydrocarbon (PAH), in Penaeus aztecus, a penaeid shrimp subject to hypoxia and PAH contamination in the northern Gulf of Mexico. For each of the two naphthalene concentrations, five groups of shrimps were, respectively, subjected to five different conditions, namely, clean seawater under normoxia, seawater containing acetone under normoxia and hypoxia, and seawater containing 10 or 250 microg/L naphthalene under normoxia and hypoxia. Our results suggest that hypoxia does not significantly alter naphthalene bioaccumulation in either the gills or the hepatopancreas of P. aztecus. The absence of a promoting effect of hypoxia on naphthalene bioaccumulation is attributed to the increased disposition of naphthalene when the shrimps are subjected to hypoxia. 相似文献
5.
An accurate method for long-term (weeks to months) projections of oil spill trajectories based on multi-year ensemble analyses
of simulated surface and subsurface (z = −800 m) drifters released at the northern Gulf of Mexico spill site is demonstrated during the 2010 oil spill. The simulation
compares well with satellite images of the actual oil spill which show that the surface spread of oil was mainly confined
to the northern shelf and slope of the Gulf of Mexico, with some (more limited) spreading over the north/northeastern face
of the Loop Current, as well as northwestward toward the Louisiana–Texas shelf. At subsurface, the ensemble projection shows
drifters spreading south/southwestward, and this tendency agrees well with ADCP current measurements near the spill site during
the months of May–July, which also show southward mean currents. An additional model analysis during the spill period (Apr–Jul/2010)
confirms the above ensemble projection. The 2010 analysis confirms that the reason for the surface oil spread to be predominantly
confined to the northern Gulf shelf and slope is because the 2010 wind was more southerly compared to climatology and also
because a cyclone existed north of the Loop Current which moreover was positioned to the south of the spilled site. 相似文献
6.
Michael Dagg Riki Sato Hongbin Liu Thomas S. Bianchi Rebecca Green Rodney Powell 《Continental Shelf Research》2008
Nutrients from the Mississippi/Atchafalaya Rivers greatly stimulate biological production in the ‘classical’ food web on the inner shelf of the northern Gulf of Mexico. Portions of this production, especially large diatoms and zooplankton fecal pellets, sink and decompose in the bottom water, consuming oxygen and contributing to the annual development of an extensive zone of bottom water hypoxia, typically >15,000 km2 since 1993. The microbial food web is also active in the Mississippi River plume, but consists of small organisms that sink slowly. This ‘recycling’ food web has not been considered as a significant contributor to vertical flux and hypoxia. However, gelatinous zooplankton, especially pelagic appendicularians such as Oikopleura dioica, mediate the conversion of microbial web organisms to organic particles with high sinking rates. When pelagic appendicularians are abundant in coastal regions of the northern Gulf of Mexico, they stimulate the rapid vertical transfer of microbial web productivity in the surface layer, which is only 5–15 m thick in the coastal hypoxic region, to the sub-pycnocline layer that becomes hypoxic each summer. In this paper we present results from two studies examining the significance of this pathway. In both 2002 and 2004, we observed high production rates of appendicularians in coastal waters. Discarded gelatinous houses and fecal pellets from the appendicularian populations often provided more than 1 g m−2 d−1 of organic carbon for the establishment and maintenance of hypoxia in the northern Gulf of Mexico. This source of organic matter flux is especially important in regions far from the river plumes and during periods of low river discharge. Autotrophic elements of this food web are primarily supported by recycled inorganic nutrients originating in the Mississippi and Atchafalaya Rivers. Sources of dissolved organic matter (DOM) supporting the heterotrophic components of this microbial food web may include in situ production, the Mississippi/Atchafalaya Rivers, and Louisiana's coastal wetlands. If significant, the latter source provides a possible link between Louisiana's high rates of coastal land loss and the large hypoxic zone observed along the coast during summer. Both of the latter DOM sources are independent of phytoplankton production stimulated by inputs of riverine inorganic nutrients. 相似文献
7.
Since increased ventilation is known to be a common strategy used by aquatic animals to cope with hypoxia, we tested in present study the hypothesis that hypoxia can promote the bioaccumulation of naphthalene, a representative polycyclic aromatic hydrocarbon (PAH), in Penaeus aztecus, a penaeid shrimp subject to hypoxia and PAH contamination in the northern Gulf of Mexico. For each of the two naphthalene concentrations, five groups of shrimps were, respectively, subjected to five different conditions, namely, clean seawater under normoxia, seawater containing acetone under normoxia and hypoxia, and seawater containing 10 or 250 μg/L naphthalene under normoxia and hypoxia. Our results suggest that hypoxia does not significantly alter naphthalene bioaccumulation in either the gills or the hepatopancreas of P. aztecus. The absence of a promoting effect of hypoxia on naphthalene bioaccumulation is attributed to the increased disposition of naphthalene when the shrimps are subjected to hypoxia. 相似文献
8.
《Marine pollution bulletin》2009,58(6-12):307-312
Since increased ventilation is known to be a common strategy used by aquatic animals to cope with hypoxia, we tested in present study the hypothesis that hypoxia can promote the bioaccumulation of naphthalene, a representative polycyclic aromatic hydrocarbon (PAH), in Penaeus aztecus, a penaeid shrimp subject to hypoxia and PAH contamination in the northern Gulf of Mexico. For each of the two naphthalene concentrations, five groups of shrimps were, respectively, subjected to five different conditions, namely, clean seawater under normoxia, seawater containing acetone under normoxia and hypoxia, and seawater containing 10 or 250 μg/L naphthalene under normoxia and hypoxia. Our results suggest that hypoxia does not significantly alter naphthalene bioaccumulation in either the gills or the hepatopancreas of P. aztecus. The absence of a promoting effect of hypoxia on naphthalene bioaccumulation is attributed to the increased disposition of naphthalene when the shrimps are subjected to hypoxia. 相似文献
9.
A Bayesian hierarchical modeling approach for analyzing observational data from marine ecological studies 总被引：1，自引：0，他引：1
Song S. Qian J. Kevin Craig Melissa M. Baustian Nancy N. Rabalais 《Marine pollution bulletin》2009,(12):1916-1921
We introduce the Bayesian hierarchical modeling approach for analyzing observational data from marine ecological studies using a data set intended for inference on the effects of bottom-water hypoxia on macrobenthic communities in the northern Gulf of Mexico off the coast of Louisiana, USA. We illustrate (1) the process of developing a model, (2) the use of the hierarchical model results for statistical inference through innovative graphical presentation, and (3) a comparison to the conventional linear modeling approach (ANOVA). Our results indicate that the Bayesian hierarchical approach is better able to detect a “treatment” effect than classical ANOVA while avoiding several arbitrary assumptions necessary for linear models, and is also more easily interpreted when presented graphically. These results suggest that the hierarchical modeling approach is a better alternative than conventional linear models and should be considered for the analysis of observational field data from marine systems. 相似文献
10.
Keita Kodama Yoshihiro Tajima Takamichi Shimizu Satoshi Ohata Hiroaki Shiraishi Toshihiro Horiguchi 《Marine pollution bulletin》2014
We investigated effects of severe hypoxia (dissolved oxygen <1 ml l−1) on recruitment of mantis shrimp Oratosquilla oratoria in Tokyo Bay. Ten-year field surveys were conducted to examine quantitative relationships in annual mean densities of larvae and juveniles, and spatial distribution of juveniles and severe hypoxia. There was no significant correlation between annual mean densities of larvae and juveniles, suggesting that mortality during larval or juvenile stages varies among years, which might have regulated abundance of young-of-the-year juveniles. Juvenile density was low in the severely hypoxic area, implying that hypoxia could affect survivals and spatial distribution of juveniles. Meanwhile, there are yearly fluctuations in juvenile density in normoxic areas of both northern and southern part of the bay. This evidence suggests that abundance of post-settled juveniles might have been determined by not only effects of hypoxia, but also other factors influencing mortality during the early life stages. 相似文献
11.
Harry F.L. Williams 《地球表面变化过程与地形》2012,37(8):901-906
There is a paucity of information on the regional distribution and magnitude of hurricane storm surge sedimentation. This study assesses the spatial extent and magnitude of Hurricane Ike's (2008) storm surge sedimentation and discusses implications for the role of hurricanes in marsh aggradation. The characteristics of the storm surge deposit, including thickness, inland penetration, volume and mass, were determined for 15 transects across marshes bordering the Gulf of Mexico in south‐eastern Texas and south‐western Louisiana. The deposit is up to 0·85 m thick, extends up to 3·6 km inland, and has an estimated volume of about 13·7 million m3 and an estimated mass of about 16·2 million metric tons. This level of sedimentation is one to two orders of magnitude larger than other potential sources of marsh sedimentation, including annual riverine inputs and inputs from alongshore sediment transport. The study findings add support to a growing body of evidence that hurricanes may be the predominant sediment source for long‐term aggradation of many coastal marshes bordering the Gulf of Mexico. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
12.
Hurricane Rita, a category three hurricane which struck the US Gulf Coast near the Louisiana/Texas border in 2005, did not cause extensive river flooding. However, the storm did result in extensive forest damage and tree blowdown. High‐resolution post‐storm aerial photography allowed an inventory of river bank trees blown into the channel along the lower Neches and Sabine Rivers of southeast Texas and southwest Louisiana. Blowdowns directly into the channel averaged 9·3 per kilometer in the lower Neches and 13·4 in the lower Sabine River, but individual reaches 10 to 20 km in length had rates of 20 to 44 blowdowns per kilometer. Though large woody debris (LWD) from Hurricane Rita was widely perceived to reduce the capacity of channels to convey flow, no strong evidence exists of increased flooding or significant reductions in channel conveyance capacity due to LWD from the storm. The Rita blowdown inventory also allowed an assessment of whether similar blowdown events could account for major logjams and rafts on Red, Atchafalaya, and Colorado Rivers on the Gulf Coast, which blocked navigation from tens to hundreds of kilometers in the 1800s. Results from Hurricane Rita suggest that blowdown into channels alone – not withstanding blowdown elsewhere in the river valleys or along tributaries which could deliver LWD to the river – is sufficient to completely block channels, thus providing a plausible mechanism for initiating such (pre)historic log rafts. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
13.
Dirk Nürnberg Martin Ziegler Cyrus Karas Ralf Tiedemann Matthew W. Schmidt 《Earth and Planetary Science Letters》2008,272(1-2):278-289
The Loop Current mediating the oceanic heat and salt flux from the Caribbean Sea into the Atlantic Ocean and its interference with the Mississippi River discharge are critical for both the regional climate in the Gulf of Mexico area and the water vapor transport towards high northern latitudes. We present a 400-kyr record of sea surface temperature and local surface salinity from the northeastern Gulf of Mexico (IMAGES core MD02-2575) approximated from combined planktonic foraminiferal δ18O and Mg/Ca, which reflects the temporal dynamics of the Loop Current and its relationship to both varying Mississippi discharge and evolution of the Western Hemisphere Warm pool. The reconstructed sea surface temperature and salinity reveal glacial/interglacial amplitudes that are significantly larger than in the Western Hemisphere Warm pool. Sea surface freshening is observed during the extreme cool periods of Marine Isotope Stages 2, 8, and 10, caused by the strengthened Mississippi discharge which spread widely across the Gulf favored by the less established Loop Current. Interglacial and interstadial sea-surface conditions, instead, point to a strengthened, northward flowing Loop Current in line with the northward position of the Intertropical Convergence Zone, allowing northeastern Gulf of Mexico surface hydrographic conditions to approach those of the Caribbean. At these times, the Mississippi discharge was low and deflected westward, promoted by the extended Loop Current. Previously described deglacial megadischarge events further to the west did not affect the northeastern Gulf of Mexico hydrography, implying that meltwater routing from the Laurentide Ice Sheet via the Mississippi River is unlikely to have affected Atlantic Meridional Overturning Circulation. 相似文献
14.
This study documented the use of chemicals and biological products in marine and brackish water shrimp farming in Thailand, the world's top producer of farmed shrimp. Interviews were conducted with 76 shrimp farmers in three major shrimp producing regions, the eastern Gulf coast, the southern Gulf coast and the Andaman coast area. Farmers in the study used on average 13 different chemicals and biological products. The most commonly used products were soil and water treatment products, pesticides and disinfectants. Farmers in the southern Gulf coast area used a larger number of products than farmers in the other two areas. In the study, the use of more than 290 different chemicals and biological products was documented. Many of the pesticides, disinfectants and antibiotics used by the farmers could have negative effects on the cultured shrimps, cause a risk for food safety, occupational health, and/or have negative effects on adjacent ecosystems. Manufacturers and retailers of the products often neglected to provide farmers with necessary information regarding active ingredient and relevant instructions for safe and efficient use. 相似文献
15.
Eutrophication and associated occurrence of hypoxic condition could cause significant damage to marine ecosystems, resulting in considerable economic losses to fisheries and aquaculture and is a major source of stress that fish often have to contend with in order to survive. This problem is likely to be exacerbated in the coming years, since the wastewater treatment facilities is unlikely to catch up with increasing human activities. Moreover, large-scale reclamation projects in coastal areas have recently been increased, and these activities certainly have adverse impacts on water quality and fisheries resources. Coastal construction has a significant role in the development of hypoxic water by changing the current and mixing pattern of water. Changes in species composition and decreases in species richness and diversity have been well documented in hypoxic systems. Hypoxia could cause endocrine disruption in fish and eliminate populations of sensitive species. Shallow coastal areas are of great importance for the special nursery of fish and shellfish and land reclamation in these areas cause strong damage to fisheries. Although the tolerance of aquatic life to hypoxia is known, there is no information about the mortality of fish caused by hypoxia because fish can swim around it and no modeling study has yet been carried out. Criteria that influence the movement of fish are: amounts of food, water temperature and depth, dissolved oxygen concentration and nature of seabed. However, among these, water temperature and dissolved oxygen are the most crucial parameters that affect survival, movement and growth of fish. In this paper, a model of fish preference and mortality for environmental conditions was developed and applied to the Hakata Bay where hypoxic water occurs every summer. For the purpose of this study, a field survey of fish behavior under hypoxic water was conducted by releasing marbled sale (Pleuronectes yokohamae) in the inner bay. Moreover, a series of preference tests for DO, salinity and temperature in the laboratory were conducted in order to decide preference parameters of fish. Using the results of both field and laboratory studies, a sub-module of fish preference and mortality was coded within an integrated hydrothermal and eutrophication model (CHEM) to predict the behavior and mortality of marbled sale when hypoxia would occur in the bay. The model could reasonably simulate the behavior of the fish under hypoxia. An assessment of the impact of the ongoing land reclamation project of about 401 ha in the Wajiro tidal flat zones at the head of the bay on the fisheries resources was also conducted using the model. The results showed that the artificial land lowered the mortality rate of fish under hypoxic condition in the bay during the summer period. 相似文献
16.
Aerial surveys were conducted in the north-central Gulf of Mexico from June 1988 to May 1989. Sightings of marine debris and specifically large floating plastics were recorded during these surveys. Five study areas off the Louisiana coast were monitored and seasonal distribution and densities were estimated. Each study area contained plastic throughout the year. The estimated densities of plastic were largest in the offshore areas (4 & 5) and smallest in the inshore areas (1 & 3). Seasonally, density of plastic was smallest in the summer and largest in the fall. The reasons for the differences in seasons and study areas are not apparent but the amount of plastic in each area and season could be affected by variations in currents, winds, discharge from rivers, and human activity. 相似文献
17.
Luis G. Del Castillo 《Physics of the Earth and Planetary Interiors》1974,9(3):227-248
Marine geophysical studies were carried out along the coastal zone of Mexico in the Atlantic Ocean as part of CICAR and IDOE projects. An area of 200,000 km2 was covered by two reconnaissance cruises and a more limited area by tracks for more detailed research. The 15,000 km of track lines include a collection of continuous seismic profiling, bathymetry, gravity and magnetic data.The analyses and correlation of results indicate some local structure features and their relationship to the Neo-volcanic zone and the salt dome belt in the Gulf of Mexico. On the Yucatan area the results show the interaction of continental and oceanic crust at the NW border of the Caribbean Plate. 相似文献
18.
Douglas L. Smith 《Earth and Planetary Science Letters》1974,23(1):43-52
Nine heat flow values from Baja California and Sonora represent the first determinations of heat flux from Mexico and, in general, justify southerly extensions of the Basin and Range and Southern California thermal provinces of the southwestern United States. Heat flow in northern Baja California is low (0.84 hfu), consistent with known values from the Sierra Nevada Batholith, but a value of 1.23 hfu was recorded in the central area of the peninsula. Seven measurements from Sonora, averaging 2.5 hfu, are similar to Basin and Range values.Reduced heat flow values (q*) have been calculated for Sonora and are interpreted as indicative of a separate Basin and Range thermal subprovince in Mexico. A tectonic model developed for northwestern Mexico attributes the high heat flow of the Basin and Range to behind arc extension associated with the termination of Cenozoic subduction. Opening of the Gulf of California and sea-floor spreading therein has provided a vent for the release of heat accumulated under northwestern Mexico. Thus, the southern portion of the Basin and Range province (in Mexico) appears to be cooling and narrowing and a subprovince of high reduced heat flow is defined east and perhaps southwest of the Gulf of California. 相似文献
19.
Distribution and photoreactivity of chromophoric dissolved organic matter in northern Gulf of Mexico shelf waters 总被引：1，自引：0，他引：1
The distribution and photoreactivity of chromophoric dissolved organic matter (CDOM) in the northern Gulf of Mexico along the Louisiana coastal shelf were examined during three cruises in summer 2007, fall 2007, and summer 2008. The influence of the Mississippi River plume was clearly evident as CDOM levels (defined as a305) and dissolved organic carbon (DOC) concentrations were well-correlated with salinity during all cruises. Elevated CDOM and CDOM:DOC ratios of surface samples collected offshore of Atchafalaya Bay and the Breton-Chandeleur Sound complex indicated emanations of organic-rich waters from coastal wetlands are also an important source to nearshore shelf waters. Generally, CDOM and DOC levels were highest in surface waters and decreased with depth, but during summer 2007 and summer 2008, CDOM levels in near-bottom samples were occasionally higher than at mid-depths without concomitant increases in DOC. CDOM photobleaching was measured during 24 irradiations using a SunTest XLS+ solar simulator with photobleaching rate coefficients (k305) ranging from 0.011 to 0.32 h−1. For fall 2007 and summer 2008, higher k305 values were generally observed in samples with higher initial CDOM levels. However, samples collected during summer 2007 did not exhibit a similar pattern nor were there differences in photobleaching rates between surface and bottom samples. Spectral slope coefficients (S275-295 or S350-400) and DOC levels were largely unchanged after 24 h irradiations. Modeled CDOM photobleaching for northern Gulf of Mexico mid-shelf waters predicts that during the summer when solar irradiance is high and the water column becomes stratified, nearly 90% of the CDOM in the upper 1 m may be lost to photobleaching, with losses up to 20% possible even at 10 m depth. 相似文献
20.
Jorge Zavala-Hidalgo Artemio Gallegos-García Benjamín Martínez-López Steven L. Morey James J. O’Brien 《Ocean Dynamics》2006,56(3-4):333-338
An 8-year database of sea surface temperature (SST), 7 years of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color images, wind fields, and numerical model results are analyzed to identify regions and periods of coastal upwelling on the western and southern shelves of the Gulf of Mexico. On the seasonal scale, it is found that on the Tamaulipas, Veracruz, and southwestern Texas–Louisiana shelves there are upwelling favorable winds from April to August, when southeasterly winds are dominant and cold SST anomalies associated with upwelling are observed along their coasts. However, during summer, values of chlorophyll-a concentration are lower than those in autumn and winter, which are high due to advection of old bloom biological material from upstream. During winter, there is a cold front on the Tamaulipas shelf produced by advection of cold water from the Texas–Louisiana shelf and not due to upwelling. On the eastern Campeche Bank, persistent upwelling is observed due to favorable winds throughout the year with cold SST and large chlorophyll-a content along the inner shelf from May to September. On the Tamaulipas shelf, the summer upwelling delays the annual SST peak until September, while in most of the Gulf SST peaks in August. This difference is due to the end of the upwelling favorable wind conditions and the September seasonal current reversal. 相似文献