Spatial Assessment of a Biocriteria Applied to Texas Tidal Streams

Abstract

This study reports on a derived multivariate method for assessing ecosystem health within tidally influenced portions of river basins and coastal basins. These tidally influenced areas are highly productive transitional areas which serve as important nursery areas for many fish and shellfish species. Numerous Texas tidal streams under varying degrees of anthropogenic stressors were analyzed jointly with this new, standardized methodology. Physical and chemical constituents of the tidal systems, as well as their resident nekton communities, were compared with nonparametric ordination techniques in order to uncover a biocriteria that might have general applicability over large spatial scales. All of the tidal stream communities were dominated by only a few taxa that each displays tremendous euryhaline/physiological tolerances, and these abilities allow taxa utilizing tidal streams to adapt to a wide variety of environmental stressors. The absence of any clear connections between degraded water-bodies and any impaired nektonic communities should not automatically be viewed as a constraint inherent to the techniques of the methodology presented, but rather a verification that impaired tidal streams are not that common of an occurrence along the Texas coast, at least not when using nekton communities as the degradation indicator.