A Change in Fish Assemblages in the Pascagoula River, MS

<p>The Pascagoula River in southeastern Mississippi is the largest remaining un-impounded river system in the contiguous United States and have seen a change in fish assemblages over time. Examination of long-term fish assemblage data show that the mainstem Pascagoula River and its two major tributaries (mainstem Leaf and Chickasawhay Rivers) have been dominated by five abundant taxa that comprise 83% of individuals sampled, with <em>Cyprinella venusta</em> in the highest abundance. Beginning in about 2005-2006, a change in the mainstem Pascagoula River (but not mainstem Leaf and Chickasawhay rivers) was seen to an alternate assemblage where five different taxa dominate (89% of assemblage), with <em>Hybognathus nuchalis</em> now the most abundant species. Thus, a shift in fish assemblages seems to have occurred in one portion of the drainage but not the other. A potential driver for the switch in historic versus contemporary assemblage composition could have been changes in the abiotic environment, most specifically in dissolved oxygen (DO) within the Pascagoula River. Because of the differences in tolerances to the abiotic environment, <em>H. nuchalis</em> may be able to utilize a broader variety of habitats compared to <em>C. venusta </em>and be a notable factor in the reason there is a shift in relative abundances in assemblages. <em>Hybognathus nuchalis </em>can withstand pools and backwaters that are lower in DO and might do better in more extreme conditions, while <em>C. venusta</em> is unable to tolerate the harsher environments.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2020

Author dc:creator

• Barrett, Sara

Contributors dc:contributor

• Jake Schaefer
• Brian Kreiser
• Scott Clark

• Ecology
• Stable States
• Assemblages

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/719

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1792