Landscape Monitoring and Biological Indicators for Seagrass Conservation In Texas Coastal Waters : final report

Part I: Given the threats to coastal resources, implementation of a seagrass monitoring program in Texas is a top priority; however, to achieve maximum effectiveness, the program design should both detect changes in seagrass distribution, abundance, and condition as well as identify causative factors that drive those changes. Therefore, monitored habitat quality or stressor indicators should be strongly related to seagrass characteristics so that the seagrass condition at a site may be adequately characterized based on values of stressor indicators. We examined numerous abiotic and biotic variables at 40 sites in seagrass beds of Redfish Bay and East Flats to determine the strength of their relationship with seagrass biomass, density, cover and community composition. Strong relationships would suggest possible stressors as well as identify potential indicators of current and future seagrass condition. Both univariate and multivariate statistical analyses were used to assess these relationships and identify candidate variables for inclusion in a monitoring program.Part II: In support of the Texas Seagrass Monitoring Program, aerial remote sensing research has been performed to evaluate automated methods for monitoring landscape changes in seagrass beds indicative of human stressors and/or natural disturbances. This report discusses the integration of high resolution aerial color film photography, color space transformation, pixel threshold models, and geographic information system (GIS) technology to detect, assess, and monitor 1-m ground feature changes and landscape disturbances within Coastal Bend seagrass beds.Part III: This report outlines an implementation program for monitoring Texas seagrasses following protocols that evaluate seagrass condition based on landscape-scale dynamics. We recommend a hierarchical strategy for seagrass monitoring in order to establish the quantitative relationships between physical and biotic parameters that ultimately control seagrass condition, distribution, and persistence. The monitoring protocols are based on conceptual models that link: (1) light and nutrient availability to seagrass condition indicators and landscape level dynamics, including patchiness and depth limit distributions, and (2) physico-mechanical stressors, including hydrodynamic processes and human activities, to landscape feature indicators of seagrass bed degradation. The three-tiered approach follows a broad template adopted by several federal and state agencies across the country, but which is uniquely designed for Texas. This plan accommodates the immense hydrographic diversity in the State’s estuarine systems and its associated seagrass habitats, recent advances in seagrass monitoring techniques, and current economic constraints associated with long-term studies. Based on this approach, we describe a multiscale monitoring protocol that, when implemented, integrate plant condition indicators with landscape feature indicators to detect and interpret seagrass bed disturbances.Contract No. 0627Coastal Bend Bays & Estuaries Program Executive Director: Ray AllenMarine Scienc