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Cross-ecosystem nutrient transfer can enhance coral reef functioning in an otherwise oligotrophic environment. While the influence of seabird-derived nutrients on coral reef organisms is increasingly recognized, how they are integrated into reef food webs remains unclear. Cryptobenthic reef fishes are crucial for energy transfer on coral reefs, and their fast life histories imply that they respond strongly to seabird-derived nutrients. Here, we investigate how variation in nearshore seabird nutrient subsidies affects coral reef fish communities. By comparing fish communities across locations differing in seabird nutrient inputs and using stable isotope analysis, we explore nutrient integration across depth, their influence on cryptobenthic and associated larger reef fishes and investigated the relative reliance of cryptobenthic fishes on seabird-enriched benthic and non-enriched pelagic pathways. We find that, near seabird colonies, cryptobenthic fishes’ diets can transition from pelagic to benthic dominance; cryptobenthic fish communities are larger; herbivores and all feeding groups comprising potential cryptobenthic fish predators have higher biomass. Collectively, our results stress the importance of seabirds in shaping energy pathways and suggest that, even in dynamic, ocean-swept reef systems, cryptobenthic fishes can mobilize seabird subsidies and potentially act as a nutritional bridge to higher trophic levels.
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Work that body: fin and body movements determine herbivore feeding performance within the natural reef environment
Herbivorous fishes form a keystone component of reef ecosystems, yet the functional mechanisms underlying their feeding performance are poorly understood. In water, gravity is counter-balanced by buoyancy, hence fish are recoiled backwards after every bite they take from the substrate. To overcome this recoil and maintain contact with the algae covered substrate, fish need to generate thrust while feeding. However, the locomotory performance of reef herbivores in the context of feeding has hitherto been ignored. We used a three-dimensional high-speed video system to track mouth and body kinematics during in situ feeding strikes of fishes in the genus Zebrasoma , while synchronously recording the forces exerted on the substrate. These herbivores committed stereotypic and coordinated body and fin movements when feeding off the substrate and these movements determined algal biomass removed. Specifically, the speed of rapidly backing away from the substrate was associated with the magnitude of the pull force and the biomass of algae removed from the substrate per feeding bout. Our new framework for measuring biting performance in situ demonstrates that coordinated movements of the body and fins play a crucial role in herbivore foraging performance and may explain major axes of body and fin shape diversification across reef herbivore guilds.
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- Award ID(s):
- 1938571
- PAR ID:
- 10276352
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 287
- Issue:
- 1938
- ISSN:
- 0962-8452
- Page Range / eLocation ID:
- 20201903
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1098/rspb.2020.1903
