Measuring carbon and nitrogen bioassimilation, burial, and denitrification contributions of oyster reefs in Gulf coast estuaries

2018 ◽  
Vol 166 (1) ◽  
Author(s):  
Phillip Westbrook ◽  
Leanna Heffner ◽  
Megan K. La Peyre
Toxics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 35 ◽  
Author(s):  
Austin Scircle ◽  
James V. Cizdziel ◽  
Louis Tisinger ◽  
Tarun Anumol ◽  
Darren Robey

Much of the seafood that humans consume comes from estuaries and coastal areas where microplastics (MPs) accumulate, due in part to continual input and degradation of plastic litter from rivers and runoff. As filter feeders, oysters (Crassostrea virginica) are especially vulnerable to MP pollution. In this study, we assessed MP pollution in water at oyster reefs along the Mississippi Gulf Coast when: (1) historic flooding of the Mississippi River caused the Bonnet Carré Spillway to remain open for a record period of time causing major freshwater intrusion to the area and deleterious impacts on the species and (2) the spillway was closed, and normal salinity conditions resumed. Microplastics (~25 µm–5 mm) were isolated using a single-pot method, preparing samples in the same vessel (Mason jars) used for their collection right up until the MPs were transferred onto filters for analyses. The MPs were quantified using Nile Red fluorescence detection and identified using laser direct infrared (LDIR) analysis. Concentrations ranged from ~12 to 381 particles/L and tended to decrease at sites impacted by major freshwater intrusion. With the spillway open, average MP concentrations were positively correlated with salinity (r = 0.87, p = 0.05) for sites with three or more samples examined. However, the dilution effect on MP abundances was temporary, and oyster yields suffered from the extended periods of lower salinity. There were no significant changes in the relative distribution of MPs during freshwater intrusions; most of the MPs (>50%) were in the lower size fraction (~25–90 µm) and consisted mostly of fragments (~84%), followed by fibers (~11%) and beads (~5%). The most prevalent plastic was polyester, followed by acrylates/polyurethanes, polyamide, polypropylene, polyethylene, and polyacetal. Overall, this work provides much-needed empirical data on the abundances, morphologies, and types of MPs that oysters are exposed to in the Mississippi Sound, although how much of these MPs are ingested and their impacts on the organisms deserves further scrutiny. This paper is believed to be the first major application of LDIR to the analysis of MPs in natural waters.


1998 ◽  
Vol 63 (3) ◽  
pp. 397-416 ◽  
Author(s):  
Dale L. Hutchinson ◽  
Clark Spencer Larsen ◽  
Margaret J. Schoeninger ◽  
Lynette Norr

Dietary reconstruction using carbon and nitrogen stable isotopes from archaeological human bone samples from coastal Georgia and northern and Gulf Coast Florida dating between 400 B.C. and A.D. 1700 serves to illustrate the complexity of the agricultural transition in that region. Isotope analysis of 185 collagen samples drawn from early prehistoric, late prehistoric, and contact-period mortuary sites encompasses two major adaptive shifts in the region, namely the adoption of maize agriculture in late prehistory and the increased emphasis on maize during the mission period. Prior to European contact—and especially before the establishment of Spanish missions among the Guale, Yamasee, Timucua, and Apalachee tribal groups—diet was strongly influenced by local environmental factors. Before contact, coastal and inland populations had different patterns of food consumption, as did populations living in Georgia and Florida. Coastal populations consumed more marine and less terrestrial foods than inland populations. In general, maize was adopted during the eleventh century A.D. by virtually all Georgia populations. However, with the exception of the Lake Jackson site, a major Mississippian center in northern Florida, Florida populations show little use of maize before contact. Following European contact, maize became wide-spread, regardless of location or habitat within the broad region of Spanish Florida. Missionization appears to have been an important factor in the convergence of native diets toward agriculture and away from foraging. This increased emphasis on maize contributed to a decline in quality of life for native populations.


Ecosphere ◽  
2011 ◽  
Vol 2 (10) ◽  
pp. art114 ◽  
Author(s):  
J. R. Seavey ◽  
W. E. Pine ◽  
P. Frederick ◽  
L. Sturmer ◽  
M. Berrigan
Keyword(s):  

1999 ◽  
Vol 133 (3) ◽  
pp. 243-249 ◽  
Author(s):  
NIGEL G. HALFORD

The most important harvested organs of crop plants, such as seeds, tubers and fruits, are often described as assimilate sinks. They play little or no part in the fixation of carbon through the production of sugars through photosynthesis, or in the uptake of nitrogen and sulphur, but import these assimilated resources to support metabolism and to store them in the form of starch, oils and proteins. Wild plants store resources in seeds and tubers to later support an emergent young plant. Cultivated crops are effectively storing resources to provide us with food and many have been bred to accumulate much more than would be required otherwise. For example, approximately 80% of a cultivated potato plant's dry weight is contained in its tubers, ten times the proportion in the tubers of its wild relatives (Inoue & Tanaka 1978). Cultivation and breeding has brought about a shift in the partitioning of carbon and nitrogen assimilate between the organs of the plant.


Author(s):  
R.W. Carpenter

Interest in precipitation processes in silicon appears to be centered on transition metals (for intrinsic and extrinsic gettering), and oxygen and carbon in thermally aged materials, and on oxygen, carbon, and nitrogen in ion implanted materials to form buried dielectric layers. A steadily increasing number of applications of microanalysis to these problems are appearing. but still far less than the number of imaging/diffraction investigations. Microanalysis applications appear to be paced by instrumentation development. The precipitation reaction products are small and the presence of carbon is often an important consideration. Small high current probes are important and cryogenic specimen holders are required for consistent suppression of contamination buildup on specimen areas of interest. Focussed probes useful for microanalysis should be in the range of 0.1 to 1nA, and estimates of spatial resolution to be expected for thin foil specimens can be made from the curves shown in Fig. 1.


2014 ◽  
Vol 4 (1) ◽  
pp. 23-29
Author(s):  
Constance Hilory Tomberlin

There are a multitude of reasons that a teletinnitus program can be beneficial, not only to the patients, but also within the hospital and audiology department. The ability to use technology for the purpose of tinnitus management allows for improved appointment access for all patients, especially those who live at a distance, has been shown to be more cost effective when the patients travel is otherwise monetarily compensated, and allows for multiple patient's to be seen in the same time slots, allowing for greater access to the clinic for the patients wishing to be seen in-house. There is also the patient's excitement in being part of a new technology-based program. The Gulf Coast Veterans Health Care System (GCVHCS) saw the potential benefits of incorporating a teletinnitus program and began implementation in 2013. There were a few hurdles to work through during the beginning organizational process and the initial execution of the program. Since the establishment of the Teletinnitus program, the GCVHCS has seen an enhancement in patient care, reduction in travel compensation, improvement in clinic utilization, clinic availability, the genuine excitement of the use of a new healthcare media amongst staff and patients, and overall patient satisfaction.


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