Graduation Year
2024
Document Type
Thesis
Degree
M.S.
Degree Name
Master of Science (M.S.)
Degree Granting Department
Marine Science
Major Professor
Heather L. Judkins, Ph.D.
Co-Major Professor
Steven A. Murawski, Ph.D.
Committee Member
Glenn A. Zapfe, M.S.
Keywords
assemblage, diel vertical migration, generalized additive model, octopus, squid
Abstract
The abundance, distribution, and diversity of cephalopod paralarvae from the upper water column (0-130 meters) in the northern Gulf of Mexico (GOM) was studied using samples collected during six ichthyoplankton surveys between 2009 and 2012. A total of 2240 cephalopod paralarvae belonging to 21 families were examined. Octopodidae, Enoploteuthidae, and Ommastrephidae were the most abundant taxa collected in the time series. Five taxa had significantly different abundances between some sampling periods, while no significant differences in abundance occurred between any GOM regions (northwest GOM shelf, north-central GOM shelf, West Florida Shelf, GOM slope, and GOM basin). The majority of taxa were found deeper in the water column at night than during the day. Loliginidae and Pyroteuthidae showed significant differences in abundances between day and night, while Octopodidae and Pyroteuthidae showed significant differences in abundances between depth bins at night, and no taxa showed significant differences in abundances between depth bins during the day. Some individual taxa also showed evidence of diel vertical migration, including Octopodidae and Pyroteuthidae. Statistical models showed that Enoploteuthidae abundance was affected by year, season, diel period, and depth bin, while Octopodidae abundance was affected by region, season, and fluorescence, and Loliginidae abundance was affected by light transmissivity, fluorescence, and year. Four clusters of taxa were identified, influenced mainly by the most abundant taxa. The composition and abundance of the paralarval community varied between years, seasons, diel periods, regions, and depths, although some levels of these factors (e.g., GOM slope and GOM basin) did not have significant differences. Abundance and distribution of paralarvae in epipelagic waters of the northern GOM is likely related to adult spawning timing and location, vertical paralarval movement, hydrographic features, and circulation patterns dominated by the Loop Current.
Scholar Commons Citation
Riley, Shannon Leah, "Abundance, Distribution, and Diversity of the Paralarval Cephalopod Community in the Northern Gulf of Mexico" (2024). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/10554
