Galveston Bay (GB), Texas is one of the most industrialized estuaries in the United States. The western portion of upper Galveston Bay, in particular, is heavily affected by an urban watershed supporting more than 4 million people, the second largest petro-chemical complex in the world, and heavy maritime traffic traversing the Houston Ship Channel.
Photographic-identification surveys conducted by the Environmental Institute of Houston at University of Houston Clear Lake (EIH) in 2013-2015 suggest that a bottlenose dolphin population regularly uses this region. Prior studies by Texas A&M University – Galveston’s Marine Mammal Behavioral Ecology Group detailed heavy use of lower GB channels by bottlenose dolphins, but indicated little to no activity in the upper portion of the bay. Increased dolphin activity in this area may reflect the success of efforts to protect GB over the past 30 years; however, little is known about habitat use, site fidelity, stock structure or other factors that may contribute to abundance trends in this population.
EIH has partnered with the Galveston Bay Foundation to conduct research on this understudied population and establish the Galveston Bay Dolphin Research and Conservation Program (GDRCP). Through long-term photo-ID monitoring, mark-recapture techniques and remote biopsy darting, this program aims to tackle fundamental questions pertaining to the population’s ecology, health and behavior. As of March 2015, we conducted 16 boat-based surveys resulting in the observation of 364 dolphins in 56 groups. In total, 196 dolphins have been uniquely identified through photo-identification, and this research continues. Observations suggest that dolphins in upper GB forage frequently behind commercial shrimp trawlers and in the Houston Ship Channel, the region most influenced by toxic pollutants. Elevated exposure to contaminants, combined with habitat loss, noise pollution and human and fisheries interactions, place dolphins here at high risk, as evidenced by documented instances of skin disorders, fishing gear entanglements, and propeller strike injuries.
In the summer of 2015, with the help of the SDRP’s remote biopsy training team, we began sampling dolphin tissue in upper GB. Former SDRP intern and University of Houston Clear Lake graduate student, Sherah Loe, will be analyzing stable isotope markers as part of a foraging study. Analyses for concentrations of persistent organic pollutants and mercury, genetic profiles, and gene expression in relation to contaminant exposure will occur in cooperation with several research groups including NOAA/NMFS. Considering the exceptionally high levels of human activity in GB, it is imperative to continue monitoring this population, with focuses on understanding residency and habitat use patterns, as well as the impact of anthropogenic threats.
This article appeared on page 23 in the December 2015 issue of Nicks n Notches.