Louisiana Sea Grant

Abstract Volatile odor components of winterized and undeodorized menhaden (Brevoortia tyrannus) oil were characterized by dynamic headspace concentration on a porous polymer trap, thermal desorption, cryogenic focusing, high resolution gas chromatography, mass spectrometry and chromatography‐coupled descriptive odor evaluation. Many volatile odor components derived from lipid oxidation in the fish oil were identified. These included, among others, short‐chain saturated and unsaturated aldehydes and ketones, as well as short‐chain carboxylic acids. The former imparted greasy, oily, oxidized oil and green grassy or green plant‐like odors, and the latter gave rather objectionable sweaty odors. Normal alkanes were detected as major volatiles without significant odors. The odor‐significant volatile components may be used as specific flavor quality markers to determine deodorization efficiency on crude fish oil and to monitor flavor stability of purified oils. This combined analytical approach can be readily applied to the study of volatile components in other oils.

Food-grade phosphates are used in the production of foods to function as buffers, sequestrants, acidulants, bases, flavors, cryoprotectants, gel accelerants, dispersants, nutrients, precipitants, and as free-flow (anticaking) or ion-exchange agents. The actions of phosphates affect the chemical leavening of cakes, cookies, pancakes, muffins, and doughnuts; the even melt of processed cheese; the structure of a frankfurter; the bind and hydration of delicatessen meats; the fluidity of evaporated milk; the distinctive flavor of cola beverages; the free flow of spice blends; the mineral content of isotonic beverages; and the light color of par-fried potato strips. In the United States, food-grade phosphates are generally recognized as safe, but use levels have been defined for some foods by the Code of Federal Regulations, specifically Titles 9 and 21 for foods regulated by the U.S. Department of Agriculture (USDA) and the U.S. Food and Drug Administration (FDA), respectively. Standards for food purity are defined nationally and internationally in sources such as the Food Chemicals Codex and the Joint Food and Agriculture Organization and World Health Organization (FAO/WHO) Expert Committee on Food Additives.

Abstract Nature-based tourism (NBT), alternatively known as ecotourism, is a rapidly expanding area in the tourism travel sector. States such as Louisiana with a well established urban-based tourism industry may have expansion opportunities through development of complementary nature-based tourism. This study analyzes the decision to participate in nature-based tourism and identifies factors, including attitudinal, that influence the decision to participate in NBT among Louisiana tourists.

Research Article| July 01, 2000 Integrated paleontologic and paleomagnetic stratigraphy of the upper Neogene deposits around Limon, Costa Rica: A coastal emergence record of the Central American Isthmus D.F. McNeill; D.F. McNeill 1Division of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA Search for other works by this author on: GSW Google Scholar A.G. Coates; A.G. Coates 2Smithsonian Tropical Research Institute, Box 2072, Balboa, Republic of Panama Search for other works by this author on: GSW Google Scholar A.F. Budd; A.F. Budd 3Department of Geology, University of Iowa, Iowa City, Iowa 52242, USA Search for other works by this author on: GSW Google Scholar P.F. Borne P.F. Borne 4Louisiana Sea Grant College Program, Louisiana State University, Baton Rouge, Louisiana 70803, USA Search for other works by this author on: GSW Google Scholar Author and Article Information D.F. McNeill 1Division of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA A.G. Coates 2Smithsonian Tropical Research Institute, Box 2072, Balboa, Republic of Panama A.F. Budd 3Department of Geology, University of Iowa, Iowa City, Iowa 52242, USA P.F. Borne 4Louisiana Sea Grant College Program, Louisiana State University, Baton Rouge, Louisiana 70803, USA Publisher: Geological Society of America Received: 28 Feb 1999 Revision Received: 23 Aug 1999 Accepted: 30 Aug 1999 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2000) 112 (7): 963–981. https://doi.org/10.1130/0016-7606(2000)112<963:IPAPSO>2.0.CO;2 Article history Received: 28 Feb 1999 Revision Received: 23 Aug 1999 Accepted: 30 Aug 1999 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D.F. McNeill, A.G. Coates, A.F. Budd, P.F. Borne; Integrated paleontologic and paleomagnetic stratigraphy of the upper Neogene deposits around Limon, Costa Rica: A coastal emergence record of the Central American Isthmus. GSA Bulletin 2000;; 112 (7): 963–981. doi: https://doi.org/10.1130/0016-7606(2000)112<963:IPAPSO>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A chronostratigraphic study of mixed carbonate and siliciclastic sediments (Limon Group) along the Caribbean side of the Central American Isthmus was conducted to provide refined depositional ages on the uplifted, nearshore marine sequence exposed near Limon, Costa Rica. These upper Neogene sediments provide a rich faunal history that spanned the closure of the isthmus and cessation of marine circulation between the Pacific Ocean and Caribbean Sea. This faunal archive provides a critical link in regional assessment of evolutionary changes that resulted from the development of the Central American Isthmus.Results from this study have shown that integrated biostratigraphic and magnetostratigraphic techniques can be successfully combined to provide refined age dating in shallow-marine sediments, even where some microfossil reworking has occurred. We propose the new Quebrada Chocolate Formation to represent latest early–early late Pliocene mixed reefal and siliciclastic deposits that overlie the early Pliocene Rio Banano Formation. The superjacent Moin Formation is expanded to include a second reefal interval deposited near the late Pliocene-Pleistocene boundary as well as fine-grained, mollusk-rich deposits in the forereef and lagoon. The style of mixed-system reef geometry between the two units is distinct. The Quebrada Chocolate Formation reefs consist of a lower interval of alternating reefal units buried by siliciclastic sediment and an upper unit comprised of stacked, reefal buildups with relatively minor siliciclastic matrix. These stacked reefs formed on a rising sea level. In contrast, the Moin Formation reefs are isolated corals and patch reefs within a siliciclastic matrix that were deposited during the peak (maximum flooding) of the sea-level highstand.Our refined age model for the Limon Group sediments allows reassessment of Pleistocene uplift rates. We calculate a rate of about 50 m/m.y., slightly less than previous rate estimates, attributed to the shallow subduction in the Pacific of the Cocos Ridge beneath the Central American island-arc system.Development of similar high-resolution age models from other marine basins should provide the chronostratigraphic control necessary to assess environmental events and evolutionary trends in shallow-marine faunas separated and isolated by the Central American Isthmus. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

A low-molecular-weight peptide with potent antioxidative activity was obtained from Mytilus coruscus muscle protein using an in vitro gastrointestinal digestion system. The potent antioxidant peptide, which was identified as Leu-Val-Gly-Asp-Glu-Gln-Ala-Val-Pro-Ala-Val-Cys-Val-Pro (1.59 kDa), exhibited higher protective activity against polyunsaturated fatty acid (PUFA) peroxidation than the native antioxidants, ascorbic acid and alpha-tocopherol. In a free radical scavenging assay using electron spin resonance spectroscopy, hydroxyl radical formation was quenched by 75.04% in the presence of M. coruscus peptide (50 microg/mL), which was similar to ascorbic acid. In addition, the purified peptide could also quench super-oxide and carbon-centered radicals, but those activities were weaker than for ascorbic acid. This study showed that the low-molecular-weight peptide released from in vitro gastrointestinal digestion of mussel exhibited potent antioxidant potential by inhibiting the formation of reactive oxygen species formed by the peroxidation of PUFAs.

Soil and water assessment tool (SWAT) and advanced circulation (ADCIRC) models were integrated to generate a hydrologic (SWAT)–hydrodynamic (ADCIRC) model applicable for flood prediction in coastal areas. The model is applied to the lower St. Johns River Basin for a holistic postevent analysis of Tropical Storm Fay (2008). Validation of the model is presented, followed by physical-forcing and temporal assessments of inundation within the river-adjacent watershed basins. The model validation and inundation assessment demonstrates the need to apply watershed runoff as an additional boundary condition in order to more fully capture the peak surge and recession, which added ∼0.5 m to storm tide elevation in the lower St. Johns River, extended the surge recession by nearly 5 days, and increased the inundated watershed area by almost 50%. Watershed inundation ranges between ∼33 km2 for normal tide conditions and ∼150 km2 for an approximate 1-in-100-year event (Tropical Storm Fay). Implementation of the approach requires careful definition of the SWAT-ADCIRC interfaces at tributaries and river offshoots, which for the case of the lower St. Johns River Basin was accomplished with 8 inflow boundary condition locations. Other details of the approach are discussed, and general guidance for application to other estuaries is provided.

International efforts to restore degraded ecosystems will continue to expand over the coming decades, yet the factors contributing to the effectiveness of long-term restoration across large areas remain largely unexplored. At large scales, outcomes are more complex and synergistic than the additive impacts of individual restoration projects. Here, we propose a cumulative-effects conceptual framework to inform restoration design and implementation and to comprehensively measure ecological outcomes. To evaluate and illustrate this approach, we reviewed long-term restoration in several large coastal and riverine areas across the US: the greater Florida Everglades; Gulf of Mexico coast; lower Columbia River and estuary; Puget Sound; San Francisco Bay and Sacramento-San Joaquin Delta; Missouri River; and northeastern coastal states. Evidence supported eight modes of cumulative effects of interacting restoration projects, which improved outcomes for species and ecosystems at landscape and regional scales. We conclude that cumulative effects, usually measured for ecosystem degradation, are also measurable for ecosystem restoration. The consideration of evidence-based cumulative effects will help managers of large-scale restoration capitalize on positive feedback and reduce countervailing effects.

Bevington, A.E. and Twilley, R.R., 2018. Island edge morphodynamics along a chronosequence in a prograding deltaic floodplain wetland.Much of the previous research on coastal deltaic land building has focused on the planform delta dimensions; whereas this research focuses on shifts in vertical elevation and deltaic island edge cross-sectional morphology in relation to a proposed conceptual model of deltaic island edge morphological development. This study was conducted using data collected from the Wax Lake Delta in the northern Gulf of Mexico. Island edge cross-sectional elevation profiles were extracted from a 2012 LIDAR elevation survey. Four morphometric variables (levee width, interior slope, mean elevation range, and total elevation range) were selected to describe the shape of each of these profiles, and each profile was also assigned to an age class, which was determined based on mapping of historic deltaic island extent from aerial imagery. Multivariate analysis of variance was used to test the effect of age class and distance from the upstream end of the island on these four morphometric variables. Results indicated that both age and the distance within age were statistically significant predictors of island edge cross-sectional morphology. Field-surveyed elevation transects also followed the predicted pattern of morphologic change and illustrated that the shifts in morphology can occur very rapidly within this system—over a matter of a few months—as the result of a single large river flood. High soil percent organic matter was also found to correlate to high elevation in field-surveyed transects, indicating that biological processes such as organic matter production and accretion may also play an important role in morphological development of deltaic floodplain wetlands.

and will promote the commercialization of such photocatalysts in the photocatalytic degradation of organic compounds.

Rising seas increase the exposure, vulnerability, and thus the risk associated with hurricane storm surge flooding across the coastal floodplain. A methodology is applied to down select a suite of synthetic storms from recent flood insurance studies. The purpose is to force wind-wave and hurricane storm surge models of the northern Gulf of Mexico (NGOM) coast (Mississippi, Alabama, and the Florida Panhandle) that represent the future landscape and derive the 1 and 0.2% annual chance floodplain for present-day and four sea-level-rise (SLR) scenarios. Vast new regions become part of the 100-year floodplain by the end of the century. In Mississippi, the present-day 500-year return period event is likely to be the 100-year event under an SLR of 1.2 m. Throughout most of Alabama and the Florida Panhandle, the present-day 500-year return period event becomes a 100-year event with just 0.5 m of SLR. Results indicate the need to apply a coastal dynamic modeling approach to plan and prepare for the effects of SLR across the NGOM and other low-gradient coastal landscapes.

Abstract Over a century of laboratory research has explored the mechanisms of memory using a variety of paradigms and stimuli. In addition, many researchers have taken up Neisser's challenge to examine memory under real‐world conditions, most prominently including the eyewitness identification problem. Unfortunately, these ‘high road’ and ‘low road’ perspectives rarely communicate with one another, with the eyewitness field largely adopting an approach that focusses on methodological adherence to conditions that mimic real‐world situations. In the current paper we advocate for a ‘middle road’ approach that includes a focus on theory development, an emphasis on the interaction between field and laboratory research and the implementation of convergent approaches to investigating eyewitness identification. We argue that the field would be invigorated by such an approach, with benefits accruing to our understanding of eyewitness identification and to the development of procedures that will ultimately improve eyewitness accuracy. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Wetland dominated estuaries serve as one of the most productive natural ecosystems through their ecological, economic and cultural services, such as nursery grounds for fisheries, nutrient sequestration, and ecotourism. The ongoing deterioration of wetland ecosystems in many shallow estuaries raises concerns about the contributing erosive processes and their roles in restraining coastal restoration efforts. Given the combination of wetlands and shallow bays as landscape components that determine the function of estuaries, successful restoration strategies require knowledge of wind wave behavior in fetch and depth limited water as a critical design feature. We experimentally evaluate physics of wind wave growth in fetch and depth limited estuaries. We demonstrate that wave growth rate in shallow estuaries is a function of wind fetch to water depth ratio, which helps to develop a new set of parametric wave growth equations. We find that the final stage of wave growth in shallow estuaries can be presented by a product of water depth and wave number, whereby their product approaches 1.363 as either depth or wave energy increases. Suggested wave growth equations and their asymptotic constraints establish the magnitude of wave forces acting on wetland erosion that must be included in ecosystem restoration design.

The performance of the progeny of eastern oysters Crassostrea virginica from Louisiana selected for resistance to dermo, caused by Perkinsus marinus (referred to as ‘OBOY’) and of wild oysters collected from Louisiana (Calcasieu Lake) and Alabama (Cedar Point, Perdido Pass), USA, estuaries was compared for their potential use in aquaculture. Seed oysters from each stock were deployed in September 2011 at 2 dermo-endemic sites, Dauphin Island and Sandy Bay, Alabama, using an adjustable longline system, and their survival and shell heights were monitored bimonthly. P. marinus infection intensity and condition index were measured at deployment and in March, July and September 2012. The OBOY stock showed lower mortality than the unselected stocks (Cedar Point, Perdido Pass, Calcasieu Lake) at Dauphin Island, and both Louisiana stocks had lower mortality than the Alabama stocks at Sandy Bay, a slightly more saline site. Mortality increased in summer, especially between July and September, concomitant with increasing P. marinus infection intensities at the higher temperatures and favorable salinities. At the higher salinity site, both Louisiana stocks had lower P. marinus infection intensities than the Perdido Pass stock, the stock with the highest percentage of oysters with moderate and heavy infection and cumulative mortality. The OBOY stock reached greater mean shell height than Calcasieu Lake and Perdido Pass stocks. Condition index of the oyster stocks decreased by more than half between March and July following expected spawning. Differences in stock performance highlight the importance of stock selection for aquaculture in dermo-endemic estuaries of the northern Gulf of Mexico.

Abstract Boswell, K. M., and Wilson, C. A. 2008. Side-aspect target strength measurements of bay anchovy (Anchoa mitchilli) and Gulf menhaden (Brevoortia patronus) derived from ex situ experiments. – ICES Journal of Marine Science, 65: 1012–1020. Acoustic target strengths (TSs) of bay anchovy [Anchoa mitchilli, 4.7–6.1 cm TL (total length)] and Gulf menhaden (Brevoortia patronus, 5.1–7.7 cm TL) were measured at 420 kHz during side-aspect, ex situ experiments. TS–TL relationships were derived at aspect for tethered individuals, and TS distributions were compared with those of free-swimming fish. Linear models relating TS and TL were fitted to data at two levels of pulse duration (0.1 and 0.4 ms) for both side aspect and all horizontal aspects of each species, and for pooled data from both species. At a pulse duration of 0.4 ms, the side-aspect TS–TL relationships were anchovy: TSlateral = 19.5 log10 TLcm − 62.4; menhaden: TSlateral = 26.1 log10 Lcm − 65.6; pooled: TSlateral = 32 log10 TLcm − 70.9. For all horizontal-aspect orientations (0–180° in the horizontal) the best-fit TS–TL relationships were anchovy: TSall = 20 log10 TLcm− 65.4; menhaden: TSall = 20 log10 TLcm − 64.8; pooled: TSall = 20 log10 TLcm− 65. However, the “fit” for all angles was consistently low. Predicted TS comparisons with side-aspect models presented by earlier authors suggested biases in the estimated TL. Additionally, relationships between TS and wet weight (W) were derived for each species. Variation in TS by pulse-duration level suggests the potential for the use of this factor as a time-dependent variable by which to separate echoes from bay anchovy and Gulf menhaden.

Abstract We conducted hydroacoustic, gill-net, and push trawl surveys to quantify changes in habitat-specific fish size and biomass in shallow (&amp;lt;2-m) estuarine waters of Barataria Bay, Louisiana, in order to evaluate essential fish habitat. Surveys were conducted monthly between June 2003 and May 2004 among regions located along a north—south salinity gradient. The fish length distributions derived from the gill-net and push trawl catches showed moderate concordance with the measured target strength distributions, indicating that our integrated approach more effectively characterized the fish community than using only a single gear type would have. Acoustic estimates showed that biomass was highest during fall (mean ± SE; 2.30 ± 0.27 g/m3) and next highest in spring (1.49 ± 0.20 g/m3), with relatively low biomass during summer (0.70 ± 0.14 g/m3) and winter (0.86 ± 0.14 g/m3); pelagic fish biomass from nets was low during winter (53.9 ± 14.9 grams per unit effort [gpue]) but relatively high in fall (846.1 ± 207.2 gpue), spring (774.3 ± 175.5 gpue), and summer (620.3 ± 140.7 gpue). Oyster habitat supported a greater biomass of pelagic fish (acoustic survey: 1.54 ± 0.15 g/m3; gill-net survey: 467.3 ± 81.0 gpue) than soft-bottom habitat (acoustic: 0.94 ± 0.11 g/m3; gill-net: 315.2 ± 54.8 gpue). Among regions, the greatest biomass of pelagic fish was observed at polyhaline stations (acoustic: 1.78 ± 0.19 g/m3; gill-net: 654.3 ± 136.5 gpue), followed by mesohaline (acoustic: 1.18 ± 0.15 g/m3; gill-net: 378.5 ± 79.1 gpue) and oligohaline stations (acoustic: 0.82 ± 0.12 g/m3; gill-net: 228.3 ± 50.2 gpue). Gill-net biomass was linearly related to the acoustic biomass estimates of small pelagic fish. The complementary, multigear approach proved to be useful in evaluating habitat use and may be particularly helpful in identifying and monitoring ecosystem reference points to evaluate change and in standardizing ecosystem-based assessment approaches.

The benefits of exposing eastern oysters to air during commercial culture have not been well-characterized. An adjustable longline system (ALS) designed in Australia and recently adopted by the nascent aquaculture industry in the northern Gulf of Mexico, allows growing oysters at any position in the water column and is perfectly suited to study the benefits of air exposure. Four-month old diploid oysters were deployed in an ALS and divided into three groups: 1) oysters exposed to air daily for 8–12 hr during low tide, 2) oysters exposed to air weekly (~24 hr once a week), and 3) oysters kept subtidally. Oyster mortality and growth rates, Perkinsus marinus load and condition index were then determined every 3 months over 2 years, while refrigerated shelf life and Vibrio vulnificus load were determined in summer and early fall of the second year. Summer mortalities were delayed, P. marinus infection intensities tended to be lower and condition index was significantly higher in oysters exposed to air daily compared with oysters exposed to air weekly or held subtidally. Shell heights of oysters exposed to air daily were lower for most of the study due to a lower growth rate during the initial sampling interval following deployment. No consistent differences were found in V. vulnificus loads or refrigerated shelf lives between the groups. It is recommended that ALS be set so that oysters are kept subtidally fall through spring to promote growth, and exposed to air daily during summer to delay P. marinus proliferation.

Deltaic landscapes, such as the Mississippi River Delta, are sites of extensive conversion of wetlands to open water, where increased fetch may contribute to erosion of marsh edges, increasing wetland loss. A field experiment conducted during a storm passage tested this process through the observations of wave orbital and current velocities in the fringe zone of a deteriorating saltmarsh in Terrebonne Bay, Louisiana. Incident waves seaward of the marsh edge and wave orbital and current velocities immediate landward of the marsh edge were measured. Through a dimensional analysis, it shows that the current and orbital velocities in the marsh fringe were controlled by the incident waves, inundation depth, submergence ratio, and vegetation density. Similarly, it is shown that the longshore currents in the inundated saltmarsh fringe depended on the local wave-induced momentum flux, vegetation submergence, and vegetation density in the fringe zone. The cross-shore current showed the presence of a return flow in the lower region of the velocity profile. A high correlation between the current direction and the local flow-wave energy ratio as well as the vegetation submergence and density is found, indicating the important role of surface waves in the fringe flow landward of an inundated wetland under storm conditions. The field observations shed light on the potential ecological consequences of increased wave activities in coastal saltmarsh wetlands owing to subsidence, sea level rise, limited sediment supply, increases in wind fetch, and storm intensity.

The extensive coastal wetlands in Mississippi River Delta represent the seventh largest deltaic floodplain in the world, contributing to many services that sustain the economies of the region. Subsidence, sea level rise, saltwater intrusion, wave action from storms, and sediment depletion have contributed to chronic wetland losses, converting vegetated lands into open waters and increasing wind fetch. Among these factors listed, wave energy plays the largest role in marsh edge erosion in an open bay environment. Degrading barrier islands along the shoreline of this delta allow swell energy to enter protected bay areas, contributing to marsh edge erosion. Locally generated wind waves within enlarged bays also contribute to wetland loss. Quantifying the roles of swell and wind waves in marsh edge erosion is essential to any ecosystem restoration design. In this study, a numerical model is implemented to describe the wave climate of combined swell and wind waves in a deltaic estuary. Terrebonne Bay was chosen as the study area because it has experienced one of the largest reductions in barrier islands and wetland loss rates among Louisiana estuaries. A continuous wave measurement in upper Terrebonne Bay was obtained over the course of a year. A spectral wave model is used to hindcast the wave climate in the estuary. The model results are compared against the in situ wave measurement. The wave power is partitioned into swell and wind sea at different locations in Terrebonne Bay using the model results. An extensive analysis on a valid effective wave power range that directly impacts the marsh edge is performed and presented. Insight into the temporal and spatial variability of wave power is gained. Through differentiating swell and wind sea energies around the bay, improvements of long-term wave power computation for shoreline retreat prediction are made. It is found that the swell energy becomes the primary driver of marsh edge retreat in the southwest part of Terrebonne Bay as the barrier islands are degrading.

Abstract 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 of SLR with other environmental factors, and landscape metrics, which have not been fully accounted for before this study. We chose a representative marine‐dominated estuary in the northern Gulf of Mexico, Grand Bay in Mississippi, to test the concept of SLR thresholds. We developed a mechanistic model to simulate wetland change and then derived the SLR thresholds for Grand Bay. The model results show that the threshold of SLR rate in Grand Bay is 11.9 mm/year for 2050, and it drops to 8.4 mm/year for 2100 using total wetland area as a landscape metric. The corresponding SLR acceleration rate thresholds are 3.02 × 10 −4 m/year 2 and 9.62 × 10 −5 m/year 2 for 2050 and 2100, respectively. The newly developed SLR acceleration rate threshold can help quantify the temporal lag before the rapid decline in wetland area becomes evident after the SLR rate threshold is exceeded, and cumulative SLR a wetland can adapt to under the SLR acceleration scenarios. Based on the thresholds, SLR that will adversely impact the coastal wetlands in Grand Bay by 2100 will fall within the likely range of SLR under a high warming scenario ( RCP 8.5), highlighting the need to avoid RCP 8.5 to preserve these marshes.

The gray snapper (Lutjanus griseus) is a temperate and tropical reef fish that is found along the Gulf of Mexico and Atlantic coasts of the southeastern United States. The recreational fishery for gray snapper has developed rapidly in south Louisiana with the advent of harvest and seasonalrestrictions on the established red snapper (L. campechanus) fishery. We examined the age and growth ofgray snapper in Louisiana with the use of cross-sectioned sagittae. A total of 833 specimens, (441 males, 387females, and 5 of unknown sex) were opportunistically sampled from the recreational fishery from August 1998 to August 2002. Males ranged in size from 222 to 732 mm total length (TL) and from 280 g to 5700 g total weight (TW) and females ranged from 254 to 756 mm TL and from 340 g to 5800 g TW. Both edge analysis and bomb radiocarbon analyses were used to validate otolith-based age estimates. Ages were estimated for 718 individuals; both males and females rangedfrom 1 to 28 years. The von Bertalanffy growth models derived from TL at age were Lt = 655.4{1–e[–0.23(t)]}for males, Lt = 657.3{1–e[– 0.21(t)]} for females, and L t = 656.4{1–e[– 0.22 (t)]} for all specimens of known sex. Catch curves were used to produce a total mortality (Z) estimate of 0.17. Estimates of M calculated with variousmethods ranged from 0.15 to 0.50; however we felt that M= 0.15 was the most appropriate estimate based on our estimate of Z. Full recruitment to the gray snapper recreational fishery began at age 4, was completed by age8, and there was no discernible peak in the catch curve dome.