Detecting effects of herbicide runoff: the use of Cassiopea maremetens as a biomonitor to hexazinone

McKenzie, Madeline R., Templeman, Michelle A., and Kingsford, Michael J. (2020) Detecting effects of herbicide runoff: the use of Cassiopea maremetens as a biomonitor to hexazinone. Aquatic Toxicology, 221. 105442.

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Abstract

Herbicides are an integral part of global agricultural activity but can be advected into local drainages that can discharge to coastal marine systems. Herbicide runoff can impact coastal marine organisms, including those associated with coral reefs and coastal mangrove forests. In this study, the symbiotic sedentary jellyfish Cassiopea maremetens were exposed to analytical grade hexazinone to determine their sensitivity and potential for recovery after exposure to a press herbicide event of 14 days followed by a recovery period of matching duration. Bell surface area, photosynthetic yield (i.e. effective quantum yield, EQY), statolith count and zooxanthellae density were analyzed. Most metrics demonstrated significant decreases when exposed to higher concentrations of hexazinone, while EQY was significantly decreased at exposure concentrations from 31 μg/L hexazinone and above. In contrast, zooxanthellae density (cells/mm2) increased in the highest concentrations compared to control animals. At the end of the exposure period the EC50 for bell surface area, EQY, and statolith count were 176 μg/L, 81.96 μg/L, and 304.3 μg/L, respectively. Jellyfish were able to recover to similar start values for all measured metrics at the end of the 14-day recovery period, with EQY showing recovery by Day 7 of the recovery period. This study demonstrated that statolith counts as an estimate of age were not affected by herbicides. We conclude that the depressed metrics from herbicide related impacts of C. maremetens are effective indicators of a relatively recent herbicide perturbation in that the recovery timeframe for these jellyfish is relatively short.

Item ID: 62424
Item Type: Article (Research - C1)
ISSN: 1879-1514
Copyright Information: © 2020 Elsevier B.V. All rights reserved
Funders: James Cook University (JCU)
Projects and Grants: JCU Internal Research Allocation
Date Deposited: 06 Mar 2020 01:10
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 60%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050101 Ecological Impacts of Climate Change @ 40%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 60%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960307 Effects of Climate Change and Variability on Australia (excl. Social Impacts) @ 40%
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