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Drift-kelp suppresses sea urchin appetite for destruction
conference contribution
posted on 2023-05-24, 15:26 authored by Kriegisch, N, Reeves, S, Craig JohnsonCraig Johnson, Scott LingScott LingSea urchins can cause widespread overgrazing of kelp beds leading to an impoverished ‘urchin barren’ state, which can be very difficult to recover. It is therefore vital to understand the mechanisms leading to overgrazing in order to prevent it in the first instance. Here we show results form a suite of critical experiments in Port Phillip Bay, Victoria, Australia designed to understand triggers of overgrazing by the sea urchin Heliocidaris erythrogramma. We used time-lapse cameras to survey urchin movement in both barren and kelp habitats to reveal active movement of urchins towards kelp in both habitats. Furthermore, in the presence of drift-kelp, we observed less movement independent of habitat type. To further understand the role of drift-kelp in determining destructive grazing, grazing assays were performed, and showed that on grazing rates were high for both drift and attached kelp on barrens, whereas in kelp habitat only drift kelp was consumed and almost no attached algae. Finally, time-lapse monitoring before and after the experimental addition of drift-kelp, clearly demonstrated suppression of urchin foraging in the presence of drift-kelp. Our collective results provide critical experimental support demonstrating that destructive overgrazing of standing kelp beds is triggered when drift-kelp becomes in short supply.
Funding
Holsworth Wildlife Research Endowment
History
Publication title
Aquatic Biodiversity & Ecosystems: Evolution, Interactions & Global ChangeDepartment/School
Institute for Marine and Antarctic StudiesEvent title
Aquatic Biodiversity & Ecosystems: Evolution, Interactions & Global ChangeEvent Venue
Liverpool, EnglandDate of Event (Start Date)
2015-08-30Date of Event (End Date)
2015-09-04Repository Status
- Restricted