archives@tulane.edu / The goal of this dissertation was to identify the large scale effects that seasonal hypoxia
has on the benthic community, with a particular focus on groundfish, in the Gulf of Mexico
(GOMEX) while also examining ecological and physiological factors that could explain how
hypoxia alters benthic communities. Seasonal hypoxia is a rapidly growing threat, not just in the
GOMEX, but globally. Hypoxic conditions are known to impact marine organisms at the
individual level by altering behavior and reproductive physiology while also impacting marine
communities by disrupting predator prey interactions, community biomass, community
composition, and community spatial dynamics. Research into hypoxia in the GOMEX has
historically been localized, focusing on specific sub-regions with temporally limited sampling.
While this approach has produced findings of the highest quality and importance, it has also
shown that the impacts of hypoxia can be variable making the overall impact of hypoxia on
GOMEX benthic communities difficult to discern. In taking both a geographically and
temporally broad approach in comparing the abundances of marine organisms between hypoxic
sites and normoxic (normal levels of dissolved oxygen, not hypoxic) sites I found that hypoxic
sites had significantly lower biodiversity compared to normoxic sites and that 102 out of 465
examined species had significantly lower abundances in hypoxic areas compared to normoxic
areas. When I compared the diets of common groundfish species from hypoxic areas to the diets
of the same species from normoxic areas a few key differences were noted for some species,
while the diets of other species remained relatively unchanged. After comparing the
reproductive condition and presence/absence of ovarian masculinization between hypoxic areas
and normoxic areas in three species of groundfish, I found evidence of ovarian masculinization
in all three species, and evidence of reproductive impairment in two species. In this dissertation I
showed that hypoxia in the GOMEX alters the community composition and biodiversity of the
benthic community, additionally finding evidence that hypoxic conditions alter the diets and
reproductive biology of several fishes / 1 / Michael Vincent Cyrana
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_120521 |
| Date | January 2020 |
| Contributors | Cyrana, Michael (author), Bart, Henry Jr. (Thesis advisor), School of Science & Engineering Ecology and Evolutionary Biology (Degree granting institution) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | electronic, pages: 133 |
| Rights | No embargo, Copyright is in accordance with U.S. Copyright law. |
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