A potential reservoir for the brown tide organism, Aureoumbra lagunensis, in a South Texas estuary
Abstract: Blooms of the “brown tide” organism, Aureoumbra lagunensis, have occurred regularly since 1990 in Texas’ Laguna Madre and Baffin Bay, yet the source population for the blooms is unknown. Field sampling from 2013-2016 showed persistently high abundances in one tributary (Laguna Salada) of Baffin Bay, even when the bloom had dissipated in the rest of the bay. Here we present results from a study that aimed to characterize the environmental conditions, as well as phytoplankton dynamics, in Laguna Salada. Results show that chlorophyll in Laguna Salada is at times tenfold higher than Baffin Bay proper, averaging 136 µg-l vs. 15 µg-l and with A. lagunensis abundance reaching one million cells ml-1. During the study, dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) concentrations in Laguna Salada were high (200 μM and 30 μM, respectively) compared to Baffin Bay proper (62 µM and 4 µM, respectively). DIN:DIP ratios were similar (10.9 and 14.3) for Laguna Salada and Baffin Bay, suggesting nitrogen limitation of algal growth. Additional findings will be presented to highlight the characteristics of Laguna Salada that are favorable to A. lagunensis persistence.
Author: Kenneth Hayes
Institution: Texas A&M University
Location: Corpus Christ, TX, USA