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Abstract Studies of paleocommunities and trophic webs assume that multispecies assemblages consist of species that coexisted in the same habitat over the duration of time averaging. However, even species with similar durability can differ in age within a single fossil assemblage. Here, we tested whether skeletal remains of different phyla and trophic guilds, the most abundant infaunal bivalve shells and nektobenthic fish otoliths, differed in radiocarbon age in surficial sediments along a depth gradient from 10 to 40 m on the warm-temperate Israeli shelf, and we modeled their dynamics of taphonomic loss. We found that, in spite of the higher potential of fishes for out-of-habitat transport after death, differences in age structure within depths were smaller by almost an order of magnitude than differences between depths. Shell and otolith assemblages underwent depth-specific burial pathways independent of taxon identity, generating death assemblages with comparable time averaging, and supporting the assumption of temporal and spatial co-occurrence of mollusks and fishes.
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This content will become publicly available on July 8, 2026
Prehistoric archives reveal evidence of predator loss and prey release in Caribbean reef fish communities
Understanding how humans have altered coral reef food webs remains challenging due to the absence of prehistoric baselines. Here, we use fish remains preserved in fossil and archaeological deposits from Panamá and the Dominican Republic to explore how Caribbean reef fish mortality patterns have changed over millennia. By quantifying accumulation rates of shark dermal denticles (scales) and bony fish otoliths (ear stones) in reef sediments, we assess relative fish abundance, while otolith size serves as a proxy for body size at death. Comparisons of these death assemblages suggest a 75% decline in shark-derived material and a 22% reduction in the sizes of human-targeted fishes—consistent with historical exploitation. This evidence of decline in large-bodied, higher trophic level fish remains coincided with a doubling in prey fish otolith accumulation and a 17% increase in their reconstructed body sizes. These patterns in time-averaged death assemblages align with effects of release from predation, documenting an often assumed (but rarely shown) cascading effect. In contrast, otoliths of predator-sheltered cryptobenthic fishes showed no change in either accumulation or size, suggesting that ‘‘bottom–up”environmental factors were not responsible for the observed changes. Together, these data indicate that pre-exploitation predator communities strongly controlled exposed prey fishes, but this “top–down” effect diminishes rapidly toward the food chain base, especially in predator-resistant groups. Understanding trophic cascades on Caribbean reefs requires studying systems before predator depletion.
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- Award ID(s):
- 2347773
- PAR ID:
- 10629227
- Publisher / Repository:
- National Academy of Sciences
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 122
- Issue:
- 27
- ISSN:
- 0027-8424
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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