Strengthening Coastal Landscapes Room 201B
Jan 24, 2023 10:50 AM - 11:50 AM(America/Chicago)
20230124T1050 20230124T1150 America/Chicago Strengthening Coastal Landscapes Room 201B 2023 Bays and Bayous Symposium mbnep@mobilebaynep.com
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Influences of Future Changes in Watershed on Estuarine Hydrography: A Case Study of Wolf- Perdido Bay
10:50 AM - 11:05 AM (America/Chicago) 2023/01/24 16:50:00 UTC - 2023/01/24 17:05:00 UTC
Urbanization along the northern Gulf of Mexico promotes the conversion of forestlands to urban, pasture or agricultural uses. Loss of forests increases discharge and nutrient loading draining out of the watershed to the downstream estuary reducing the estuarine water quality and clarity. Meanwhile, the lack of flushing due to weak tides together would make the ecosystem in estuaries along northern Gulf coast even vulnerable. Yet the impacts of future changes in land use/land cover and climate on estuarine physical and biogeochemical processes are not well characterized. Hence, to understand the forest changes in the watershed on the physical processes in the Wolf-Perdido Bay, we develop a three-dimensional hydrodynamic model using the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM). The model is calibrated and validated with hydrographic observations. By integrating the hydrodynamic model with a regional downscaling climate model and a watershed model, scenario studies are conducted to predict the responses of estuarine processes including vertical stratification, transport and mixing to multiples levels of land use/land cover changes in the watershed. The results from this work will reveal the relevant importance of forest changes in watershed in relation to natural variability of downstream estuaries and improve our understanding and predictions of how the Wolf-Perdido Bay's quality evolve in the future.
Presenters Zhilong Liu
University Of South Alabama, Dauphin Island Sea Lab
Co-Authors
JL
John Lehrter
University Of South Alabama, Dauphin Island Sea Lab
BD
Brian Dzwonkowski
University Of South Alabama, Dauphin Island Sea Lab
LL
Lisa Lowe
North Carolina State University
Seasonal Salinity Trends in the Central and Southern Biscayne Bay, Florida
11:05 AM - 11:20 AM (America/Chicago) 2023/01/24 17:05:00 UTC - 2023/01/24 17:20:00 UTC
Salinity in estuaries varies naturally due to tides, weather, and climate. Historical water management in southern Florida focused on diverting freshwater quickly out to ocean to make room for development. Current management activities are aimed at slowing freshwater flow to the ocean, thereby decreasing salinity within Biscayne Bay. The spatiotemporal variability in salinity within the Biscayne Bay due to anthropogenic causes is a major concern for ecosystem restoration under the Comprehensive Everglades Restoration Plan (CERP). The hypothesis of this study is that due to restoration efforts, the trend in salinity should show a decrease in the dry and wet seasons since restoration began. In order to test the hypothesis, trend (decadal) tests on a seasonal timescale were analyzed. Seasonal (dry and wet) trends in salinity (minimum, average and maximum) from measured data across sixteen stations (2005 – 2020) within the central and southern regions of the Biscayne Bay were examined. The non-parametric trend test, Modified Mann Kendall (MMK) at 0.05 significance level, was used for the analysis. Trend results show increasing salinity in the wet season and decreasing salinity in the dry season, contradicting the hypothesis. Increase in salinity in the wet season amidst restoration efforts, indicate the role of sea level rise and/or changing seasonal rainfall patterns. This study's results are important for forecasting seasonal salinity patterns and help in managing salinity in the event of climate change and sea level rise in Biscayne Bay towards achieving the goal of CERP. 
Keywords: CERP, Biscayne Bay, Salinity, Trend analysis.
Presenters
MR
Meena Raju
Auburn University
Co-Authors
AL
Anna Linhoss
Auburn University
PM
Paul Mickle
Mississippi State University, Northern Gulf Institute
CK
Chris Kelble
National Oceanic And Atmospheric Administration, Ocean Chemistry And Ecosystems Division
VA
Vladimir Alarcon
Modeling Oyster Larval Development and Success to Metamorphosis in the Mississippi Sound
11:20 AM - 11:35 AM (America/Chicago) 2023/01/24 17:20:00 UTC - 2023/01/24 17:35:00 UTC
Eastern oysters (Crassostrea virginica) are critical estuarine organisms for the various ecosystem services they offer and for their economic value as a fishery resource. Therefore, successful reef recovery is a central concern for the western Mississippi Sound after the 2019 Bonnet Carré freshwater diversion mass mortality event. Effective oyster reef recovery requires an adequate larval stock competent of timely development and metamorphosis. The health and growth of oyster larvae through to metamorphosis is determined by ambient water conditions, food quantity, and also food quality. Oyster larvae require a balanced protein, carbohydrate, and lipid diet to sufficiently develop, survive, and successfully metamorphose. Water samples were collected at seven established western Mississippi Sound oyster reefs to quantify the biochemical constituents in the available food supply alongside temperature and salinity measurements throughout the 2021 spawning season (May through October). Environmental data were incorporated into a previously developed biochemically based larval performance model to estimate survivorship and success at metamorphosis. The model is unique in that it includes genetic variation among larval cohorts, tracks weight and length separately to assess condition index, and characterizes larvae and food by their biochemical composition. Simulations suggest that conditions at four of the seven reefs promoted metamorphosis, although larval survivorship was constrained to a 100-day period within the entire spawning season. Low salinity and inadequate food supply account for high larval mortality. Model estimations are corroborated by observations of minimal recruitment to the oyster reefs.
Presenters James Klein
University Of Southern Mississippi, Gulf Coast Research Lab
USM Marine Science
University of Southern Mississippi, Gulf Coast Research Lab
Auburn University
University of South Alabama, Dauphin Island Sea Lab
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