Gulf Estuarine Research Society 2014 Meeting

Table of Contents: Thank You to Our Sponsors! (p. 3) -- About the Gulf Estuarine Research Society (p. 4) -- Student Travel Award winners (p. 5) -- Abbreviated Schedule (p. 7) -- 2014 Plenary Speaker – Dr. Michael Osland (p. 8) -- 2014 Plenary Speaker – Dr. Maggie Walser (p. 9) -- Full Schedule (p. 10) -- Poster Session Directory (p. 17) -- Oral Presentation Abstracts (p. 21) -- Poster Presentation Abstracts (p. 38) -- Things to Do in Port Aransas (p. 52) -- Greening the Meeting (p. 53) -- Map of University of Texas Marine Science Institute (p. 54)Coastal and Estuarine Research Foundation, Port Aransas, Gulf of Mexico Foundation, Coastal Bend Bays & Estuaries Program, Lotek Wireless Fish & Wildlife Monitoring, Sea Grant Mississippi-Alabama, Sea Grant Louisiana, Sea Grant Texas, The University of Austin Marine Science Institute, Mission-Aransas National Estuarine Research ReserveMarine Scienc

Influence of topography and moisture and nutrient availability on green alder function on the low arctic tundra, NT

The Arctic has warmed by at least 3°C over the past 50 years and this rapid warming is expected to continue. Climate warming is driving the proliferation of shrubs across the tundra biome with implications for energy balance, climate, hydrology, nutrient cycling, and biodiversity. Changes in tundra plant water use attributable to shrub expansion are predicted to increase evapotranspirative water loss which may amplify local warming and reduce run-off. However, little is known about the extent to which shrubs will enhance evapotranspirative water loss in these systems. Direct measures of shrub water use are needed to accurately predict evapotranspiration rates and the associated hydrological and energetic impacts. In addition, it is crucial that we understand the abiotic factors that drive shrub distribution and physiological function to forecast further changes in tundra ecosystem function. Shrubs are expanding in areas that have a higher potential of accumulating moisture, such as drainage channels and hill slopes. Shrub expansion may be limited by variation in water and nutrient availability across topographic gradients. Nevertheless, the associations between shrub function and abiotic limitations remain understudied. To address these knowledge gaps, we measured sap flow, stem water potential, and a range of functional traits of green alder (Alnus viridis) shrubs and quantified water and nutrient availability in shrub patches on the low arctic tundra of the Northwest Territories. Frost table depth was a significant negative driver of sap flow and underlies decreased surface water availability with thaw. This was further supported through significantly lower stem water potential values as the growing season progressed. Shrubs in upslope locations had significantly lower water potentials relative to shrubs in downslope locations, demonstrating topographic variation in shrub water status. Shrubs in channels and at the tops of patch slopes significantly differed in leaf functional traits representing leaf investment, productivity, and water use efficiency. Channel shrubs reflected traits associated with higher resource availability and productivity whereas shrubs at the tops of patches reflected the opposite. This work provides insight into the abiotic drivers of tall shrub water use and productivity, both of which will be essential for predicting ecosystem function

2014 Texas Bays and Estuaries Meeting

Program for the 2014 Texas Bays and Estuaries Meeting held in Port Aransas, Texas, April 23-24, 2014.Coastal Bend Bays & Estuaries Program, Woody's Sports Center, Coastal Bend Bays Foundation, The University of Texas Marine Science Institute, and Mission Aransas National Estuarine Research ReserveMarine Scienc

FRESHWATER RUNOFF FROM PACIFIC-DRAINING CONTINENTAL AND COASTAL BASINS IN PATAGONIA: CHARACTERIZING REGIONAL INPUTS TO CHILEAN FJORDS ASSOCIATED WITH CHANGES IN LAND USE/COVER

The region of west-southern Patagonia (WSP), characterized by its wild and remote landscapes, represents one of the last bastions of pristine natural environments on Earth. With recent colonization and limited human intervention, a significant portion of this territory retains its natural state. WSP boasts mighty rivers, expansive lakes, and the world's largest temperate icefields, making it a geographically distinct area. Unlike the northern Andes, it lacks a central valley, resulting in relatively short linear distances and steep gradients from source to sea. This topography shapes an intricate system of channels and fjords, contributing to one of the world's most extensive coastlines. The freshwater discharges into channels and fjords create a two-layer vertical structure, impacting various environmental parameters such as salinity, temperature, biogeochemistry, light availability, and biological communities. However, the variability of these discharges, influenced by factors like precipitation, temperature, landforms, vegetation, and land use, adds complexity to the system. While the importance of freshwater discharges in Patagonia's coastal ecosystems is recognized, understanding their magnitude, nutrient content, seasonal variations, and responses to climate change remains incomplete. Monitoring is limited to major rivers, with substantial gaps in the archipelago area, which receives higher precipitation. Besides, headwater streams, sensitive to land use and climate changes, have received less attention than larger rivers. This research aims to quantify freshwater coastal discharges in WSP and assess the impacts of land use and cover changes on runoff. Specific objectives include characterizing runoff in terrestrial basins, identifying bioindicators of land use change effects, and exploring relationships between hydrology indicators, land use, and climate variables. The study employs macro-scale and regional approaches across coastal basins and intensive micro-scale investigations in headwater streams. Chapter 1 focuses on estimating freshwater discharges in the entire study area using a hydrological model, considering factors such as soil, geology, land use, and climate. Chapter 2 investigates freshwater inputs into inner fjords, analyzing sources like precipitation, coastal runoff, and glacial ablation. Chapter 3 conducts a micro-scale analysis of headwater streams to detect early effects of land use changes and assess the impact of different hydrological regimes. Additional regional studies in appendices examine the influence of land use change on aquatic macroinvertebrate communities and identify bioindicators for forest degradation in Patagonia's evergreen forests. This research contributes essential insights into the hydrological and ecological dynamics of WSP, a region of global significance for its pristine nature and ongoing environmental changes

Hydrological and environmental variables outperform spatial factors in structuring species, trait composition, and beta diversity of pelagic algae

There has been increasing interest in algae-based bioassessment, particularly, trait-based approaches are increasingly suggested. However, the main drivers, especially the contribution of hydrological variables, of species composition, trait composition, and beta diversity of algae communities are less studied. To link species and trait composition to multiple factors (i.e., hydrological variables, local environmental variables, and spatial factors) that potentially control species occurrence/abundance and to determine their relative roles in shaping species composition, trait composition, and beta diversities of pelagic algae communities, samples were collected from a German lowland catchment, where a well-proven ecohydrological modeling enabled to predict long-term discharges at each sampling site. Both trait and species composition showed significant correlations with hydrological, environmental, and spatial variables, and variation partitioning revealed that the hydrological and local environmental variables outperformed spatial variables. A higher variation of trait composition (57.0%) than species composition (37.5%) could be explained by abiotic factors. Mantel tests showed that both species and trait-based beta diversities were mostly related to hydrological and environmental heterogeneity with hydrological contributing more than environmental variables, while purely spatial impact was less important. Our findings revealed the relative importance of hydrological variables in shaping pelagic algae community and their spatial patterns of beta diversities, emphasizing the need to include hydrological variables in long-term biomonitoring campaigns and biodiversity conservation or restoration. A key implication for biodiversity conservation was that maintaining the instream flow regime and keeping various habitats among rivers are of vital importance. However, further investigations at multispatial and temporal scales are greatly needed

A Simplified Approach for Estimating Soil Carbon and Nitrogen Stocks in Semi-Arid Complex Terrain

We investigated soil carbon (C) and nitrogen (N) distribution and developed a model, using readily available geospatial data, to predict that distribution across a mountainous, semi-arid, watershed in southwestern Idaho (USA). Soil core samples were collected and analyzed from 133 locations at 6 depths (n=798), revealing that aspect dramatically influences the distribution of C and N, with north-facing slopes exhibiting up to 5 times more C and N than adjacent southfacing aspects. These differences are superimposed upon an elevation (precipitation) gradient, with soil C and N contents increasing by nearly a factor of 10 from the bottom (1100 m elevation) to the top (1900 m elevation) of the watershed. Among the variables evaluated, vegetation cover, as represented by a Normalized Difference Vegetation Index (NDVI), is the strongest, positively correlated, predictor of C; potential insolation (incoming solar radiation) is a strong, negatively correlated, secondary predictor. Approximately 62% (as R2) of the variance in the C data is explained using NDVI and potential insolation, compared with an R2 of 0.54 for a model using NDVI alone. Soil N is similarly correlated to NDVI and insolation. We hypothesize that the correlations between soil C and N and slope, aspect and elevation reflect, in part, the inhibiting influence of insolation on semi-arid ecosystem productivity via water limitation. Based on these identified relationships, two modeling techniques (multiple linear regression and cokriging) were applied to predict the spatial distribution of soil C and N across the watershed. Both methods produce similar distributions, successfully capturing observed trends with aspect and elevation. This easily applied approach may be applicable to other semi-arid systems at larger scales