8:30 am
9:30 am
MARINE BIOLOGY PROGRAM
DEPARTMENT OF LIFE SCIENCES
TEXAS A&M UNIVERSITY-CORPUS CHRISTI
SUBJECT: Phytoplankton dynamics in an urbanizing South Texas estuary, Corpus Christi Bay, TX
MAJOR ADVISOR: Dr. Michael Wetz
ABSTRACT
Corpus Christi Bay is a low inflow estuary located on the south Texas coast that has a rapidly urbanizing watershed and is subject to near annual occurrence of Karenia brevis red tide blooms. Increasing demands for freshwater and a shift to a warmer and drier climate predicted for this region have the potential to further decrease freshwater inflows to the estuary, resulting in decreased nutrient inputs, increased salinity, and increased water residence time. To date, however, there has been little work to quantify patterns in phytoplankton biomass, community composition, or their environmental drivers.
Phytoplankton biomass in Corpus Christi Bay displayed relationships with nutrients, precipitation, and temperature. Accumulation of phytoplankton biovolume during the spring and summer were limited by the availability of nutrients, whereas hydraulic flushing and decreased temperatures were also important during the fall and winter, respectively. Phytoplankton community composition was also driven by seasonal changes in nutrients, precipitation, and temperature, with diatoms favored under cool, nutrient replete conditions and dinoflagellates favored under warm, nutrient depleted conditions. Results from nutrient addition bioassays supported these findings and indicated that nitrogen was the nutrient predominantly limiting phytoplankton growth. Lastly, this study quantified K. brevis red tide frequency, duration, and environmental drivers. Results show a long-term increase in K. brevis frequency in the Nueces Estuary, which correlated with increased salinity and decreased precipitation during non-El Niño periods and the negative phase of the North Atlantic Oscillation. Additionally, duration was inversely related to temperature and wind speed, with fall-like temperatures and calm water conditions conducive to prolonging red tides. Together, this research improves our understanding of factors driving phytoplankton dynamics in a rapidly urbanizing, low-inflow estuary.
Results suggest that Corpus Christi Bay may currently be buffered against the occurrence of large, nutrient-driven phytoplankton blooms due to the opposing influences of nutrient availability and increased flushing (during rain events). Evidence presented here suggests that future changes in climate patterns, such as overall decreased precipitation and warmer temperatures, are likely to result in changes in both the frequency, timing and composition of phytoplankton blooms, and this study provides the basis for additional hypothesis-based studies to address these issues.
TO VIEW VIA MICROSOFT TEAMS:
Join on your computer or mobile app
Click here to join the meeting
Or call in (audio only)
+1 361-434-5376,,60388467# United States, Corpus Christi
Phone Conference ID: 603 884 67#
Find a local number | Reset PIN