Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production?
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Miami University / OhioLINK
2007
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=miami1186153732 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-miami11861537322021-08-03T05:40:15Z Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? Stoeckel, James A. Daphnia parvula atrazine Acton lake reservoir herbicide retention cost of male production timing of sexual reproduction Herbicides and reservoirs are ubiquitous in the Midwestern United States. Reservoirs can act as storage units, slowly releasing herbicides into outflowing stream(s). Atrazine is the most widely used herbicide in the world. Previous studies yielded conflicting results regarding its ability to stimulate male production by Daphnia, an effect hypothesized to lower population growth rates. In this study, atrazine consistently flushed into Acton Reservoir during spring. The reservoir had positive and negative effects on atrazine exposure times: occasionally diluting atrazine below 10 µg L-1 but always extending exposure times to 5 and 3 µg L-1 thresholds. Release of atrazine-laden water by the reservoir also extended exposure times in the outflowing stream. Reservoir Daphnia exhibited excess male production during high atrazine exposure in 2003. However, in laboratory studies, Daphnia did not increase male production in response to atrazine, regardless of food availability, population growth phase, or exposure history. Laboratory populations of D. parvula invested in sexual reproduction while conditions were favorable for population growth, and returned to asexual reproduction under unfavorable conditions. Males were produced across a wide range of environmental conditions whereas ephippial females appeared only briefly. There was a cost to male production in terms of reduced carrying capacity, but not population growth rate. There were also windows within which Daphnia could increase male production without producing fewer parthenogenetic neonates. Increased male production seemed a significant disadvantage between clones only when level of investment in male production was high, and populations were at or near carrying capacity. Excess male production may be a common strategy of D. parvula clones rather than an indicator of endocrine disruption. Unlike atrazine, JHA (juvenile hormone analog) insecticides enhance male production by Daphnia and are likely to have other developmental effects on crustacean taxa. If JHAs are also stored and released by reservoirs, acute effects may be most important upstream of reservoirs, and chronic effects within and downstream of reservoirs. For ecologists, the ubiquity of reservoirs, coupled with annual flushing of agrochemicals from fields to streams, should elevate the importance of considering presence and location of reservoirs when assessing effects of land use on freshwater communities. 2007-08-03 English text Miami University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=miami1186153732 http://rave.ohiolink.edu/etdc/view?acc_num=miami1186153732 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Daphnia parvula atrazine Acton lake reservoir herbicide retention cost of male production timing of sexual reproduction |
| spellingShingle |
Daphnia parvula atrazine Acton lake reservoir herbicide retention cost of male production timing of sexual reproduction Stoeckel, James A. Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? |
| author |
Stoeckel, James A. |
| author_facet |
Stoeckel, James A. |
| author_sort |
Stoeckel, James A. |
| title |
Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? |
| title_short |
Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? |
| title_full |
Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? |
| title_fullStr |
Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? |
| title_full_unstemmed |
Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? |
| title_sort |
herbicides, reservoirs, and daphnia reproduction: is there a cost to male production? |
| publisher |
Miami University / OhioLINK |
| publishDate |
2007 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=miami1186153732 |
| work_keys_str_mv |
AT stoeckeljamesa herbicidesreservoirsanddaphniareproductionisthereacosttomaleproduction |
| _version_ |
1719423327285542912 |