Spatial-Temporal variability in phytoplankton biomass and community composition in Texas residential canals

Harmful algal blooms (HABs) are a natural phenomenon that appear to be increasing worldwide alongside the spread of urbanization and cultural eutrophication. As urbanization increases, many regions around the globe, including Texas, are seeing a significant increase in the number of residential canal systems along their coastlines. These canals pose unique attributes that may enhance conditions for HABs, namely shallow depths, high susceptibility to urban runoff, reduced mixing, and long residence times. Despite this, there has been little research on the water quality and phytoplankton composition of these systems. In this study, water quality and phytoplankton biomass/composition were analyzed in three sites along a mouth-interior gradient of a canal system on Padre Island (Corpus Christi, Texas). It was hypothesized that sites toward the interior of the canal system would experience increased nutrient availability, stratification, phytoplankton biomass/HAB occurrence, and reduced flow. The site at the mouth of the canal system exhibited lower nutrient concentrations and was less susceptible to temporal changes like storm events and stratification than the interior canal sites. Total biovolume did not vary among the three sites; however, phytoplankton composition did. The mouth site was diatom dominant, whereas the interior canals had higher picoplankton biovolumes. Ultimately, this research will (1) assess the water quality along the gradient of the canal system and (2) determine baseline conditions for future monitoring to evaluate shifts in phytoplankton composition and water quality.