Analyses of biological communities and development of indices of biotic integrity for monitoring tidal streams along the upper Texas coast

Tidal streams along the upper Texas coast are characterized by large heterogeneity in abiotic conditions and biotic communities, posing challenges to managers seeking to assess their ecological condition and develop effective management strategies. There is currently no standardized protocol for assessing ecological condition in Texas tidal stream systems. The goal of the current study was to create multimetric indices of biotic integrity (IBIs) from nekton and benthic macroinfaunal community metrics that were effective in discriminating between degraded “test” and non-degraded “reference” streams (classified by watershed land-cover data). Fifteen tidal streams were sampled twice per year in 2018 and 2019 to assess water quality, nekton, and benthic macroinfaunal dynamics. In order to create the multimetric indices of biotic integrity, multiple univariate metrics were assessed to determine the extent to which they differentiated between test and reference sites. Selected metrics were used as components in developing the multimetric IBIs, which give higher scores to samples that have similar biotic characteristics to our reference condition samples. Multivariate analyses provided a complementary approach to selection of IBI metrics by visualizing, comparing, and identifying community-level changes as well as taxa that associate with the test or reference condition. Results indicated that overall differences in biological communities between test and reference sites were often not extremely strong. Multivariate analyses indicated nekton communities exhibited stronger differentiation between test and reference samples whereas benthic macrofaunal communities were influenced more by year to year variations. However, several univariate metrics highlighted components of communities that did differ between test and reference sites, and these metrics were used to form the IBI. Comparing IBIs for both nekton and benthic macroinfauna can provide a more comprehensive understanding of biotic integrity in tidal streams than focusing on one or the other. Results should be interpreted with some caution but could help inform water resource management decisions that seek to support aquatic life use while balancing human needs for food, recreation, and industry.Life SciencesCollege of Science and Engineerin