Amphidromous species migrate between fresh water and the sea for larval development. Many caridean shrimps, especially Macrobrachium spp., are amphidromous, and some populations are found far-upstream within continental river systems. This project tested the hypothesis that populations of Macrobrachium ohione from the Atchafalaya and Mississippi Rivers are amphidromous.
In the laboratory, I tested the hypothesis that upstream populations of M. ohione have freshwater larval development. My results indicated that saline habitats are essential for M. ohione development, and larval mortality increased after 3-4 days of freshwater drifting. This provides indirect evidence that upstream populations have extended marine larval development.
Due to their limited freshwater survival, M. ohione must deliver larvae to the sea. Spatial-temporal analysis in the Atchafalaya and Mississippi Rivers reported an influx of reproductive-sized shrimps and females with near-hatching broods into coastal sites. This suggests that females are migrating downstream to hatch larvae in downstream habitats.
Stable isotope analysis indicated that the upstream juvenile migration originates from saline habitats. Video surveillance revealed that juveniles migrate throughout the night at an average speed of ∼ 0.56 km hr -1, and swimming speeds were related to the water velocity they swam against. From these results, I estimated that juveniles are capable of migrating to far-upstream habitats within their life span (1-2 years).
Lastly, I investigated how dams affect the juvenile migration, and tested juvenile migrant climbing abilities. This study reported greater densities of juveniles downstream of dams than upstream of dams, indicating the dams impede the juvenile migration downstream of Old River Control. Shrimp climbing studies revealed that at various inclinations and water velocities, ~ 52% of the shrimps were climbing the shrimp ramp and ~ 12% completed the climb. These results demonstrated juveniles can climb bypass structures with detectable water flows.
My findings suggest that M. ohione populations within the Mississippi River System are amphidromous, because they require marine larval development and long-distance migrations are conducted to and from the sea. This study may serve as a general model for migrations of amphidromous shrimps in comparable large rivers, and potentially contribute to freshwater shrimp conservation.
|Advisor:||Bauer, Raymond T.|
|Commitee:||France, Scott C., Klerks, Paul L., McRae, Mark G., Moon, Brad R.|
|School:||University of Louisiana at Lafayette|
|Department:||Environmental and Evolutionary Biology|
|School Location:||United States -- Louisiana|
|Source:||DAI-B 74/12(E), Dissertation Abstracts International|
|Subjects:||Biology, Ecology, Zoology|
|Keywords:||Amphidromy, Diadromy, Life history, Migrations, Mississippi river, River shrimp|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be