Effects of Dispersed Oil on Marine Plankton and Planktonic Food Webs in the Gulf of Mexico
Abstract
Dispersants break down crude oil into small droplets, increasing the level of exposure of soluble toxic oil compounds to marine organisms. These smaller droplets are also often within the size range of the food that most zooplankton consume. Many species of zooplankton have demonstrated the ability to consume these dispersed oil droplets, indicating that dispersants can further promote the entry of oil toxins into marine food webs. Oil and dispersant toxicity experiments have been performed with single species of cultured phytoplankton and protozoa, and with wild-caught zooplankton in laboratory experiments. Toxicity experiments have also been performed on natural assemblages of plankton species from the Gulf of Mexico and coastal Texas bays in microcosm and mesocosm experiments. Our studies have indicated that dispersant-treated crude oil is generally more toxic to all types of marine plankton than crude oil or dispersant alone. However, the toxicity of these pollutants also varies considerably among individual species and broad taxonomic groups. When natural plankton assemblages are exposed to chemically dispersed crude oil in microcosm and mesocosm experiments, the plankton community changes its composition over time spans of a few days due to the differences in sensitivity to oil toxins among species and due to the resulting changes in predator-prey relationships in the planktonic food web. However, the overall abundance and biomass of planktonic organisms may not be significantly changed, making the effects of oil toxins on trophic transfer up the food web unclear. Given the rapid reproduction rates of most phytoplankton and many zooplankton species, recovery of planktonic food webs would be expected to be much more rapid than recovery of higher pelagic trophic levels or sensitive nearshore environments such as marshes or coral reefs. The differential impacts of oil on various marine environments needs to be considered when deciding on oil spill clean-up options.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMOS21D1761B
- Keywords:
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- 3022 Marine sediments: processes and transport;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4815 Ecosystems;
- structure;
- dynamics;
- and modeling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL;
- 4803 Analytical chemistry;
- OCEANOGRAPHY: CHEMICAL;
- 4894 Instruments;
- sensors;
- and techniques;
- OCEANOGRAPHY: CHEMICAL