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This preprint analyzes 26 years of underwater visual survey data from Cocos Island National Park to characterize elasmobranch species co-occurrence and how interspecific interactions shape species abundance, diversity, and community interactions using network statistics, diversity indices, and Bayesian interaction models. The authors report that the community shifted from a sparse, low-richness network in the early 1990s to a more diverse, densely connected community in the late 2010s, with diversity peaking in 2006. They identify three interaction types—competition, predation, and ecosystem preference—and find that scalloped hammerhead and whitetip reef sharks largely drive year-to-year diversity variation, while most species show negative relationships with the co-occurrence of other elasmobranchs. The paper explicitly notes limitations typical of the approach and emphasizes its use as a framework, and it is not peer reviewed. The paper does not explicitly discuss endometriosis or adenomyosis; it was included in the corpus via a keyword match in the upstream search index.
Abstract
Marine ecosystems support a diverse array of co-occurring species, whose presence and abundance influence the behavior, population dynamics, and distribution of interacting organisms. Elasmobranchs play a central role in marine ecological processes as top and meso-predators across various ecosystems. Previous work has shown that some elasmobranchs are key to ecosystem health and resilience, regulating communities through competitive, predatory, and territorial interactions. However, few studies have evaluated the effect of interspecific interactions on the abundance and diversity of individual populations in marine ecosystems, partly due to the difficulty of obtaining long-term data on species co-occurrence. Our objective was to analyze elasmobranch species co-occurrence in Cocos Island National Park in the Eastern Tropical Pacific and its effect in species abundance, diversity, and interactions within the community. We analyzed a 26-year underwater visual survey dataset through network statistics, diversity indices, and Bayesian species interaction models. Here we show that the elasmobranch community in early 1990s shifted from a sparse, low richness network to a more diverse, densely connected community in the late 2010s, with diversity peaking in 2006. We identified three types of species interactions within the elasmobranch community: competition, predation, and ecosystem preference. The Scalloped hammerhead (Sphyrna lewini) and Whitetip reef (Triaenodon obesus) sharks were the main contributors to year-to-year variations in diversity. In addition, most species had a negative relationship with the co-occurrence of other elasmobranchs, underscoring the importance of potential competitive and predatory interactions. Our findings offer valuable insights for marine conservation efforts, particularly for understanding how interspecific interactions and ecological processes influence ecosystem stability over time. Our study provides a framework for future research on species co-occurrences in marine ecosystems, emphasizing the need for integrated, interaction-focused models that can better predict ecosystem responses to threats like overfishing and environmental change.
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This is a Preprint and has not been peer reviewed. This is version 2 of this Preprint.
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This is a Preprint and has not been peer reviewed. This is version 2 of this Preprint.
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Marine ecosystems support a diverse array of co-occurring species, whose presence and abundance influence the behavior, population dynamics, and distribution of interacting organisms. Elasmobranchs play a central role in marine ecological processes as top and meso-predators across various ecosystems. Previous work has shown that some elasmobranchs are key to ecosystem health and resilience, regulating communities through competitive, predatory, and territorial interactions. However, few studies have evaluated the effect of interspecific interactions on the abundance and diversity of individual populations in marine ecosystems, partly due to the difficulty of obtaining long-term data on species co-occurrence. Our objective was to analyze elasmobranch species co-occurrence in Cocos Island National Park in the Eastern Tropical Pacific and its effect in species abundance, diversity, and interactions within the community. We analyzed a 26-year underwater visual survey dataset through network statistics, diversity indices, and Bayesian species interaction models. Here we show that the elasmobranch community in early 1990s shifted from a sparse, low richness network to a more diverse, densely connected community in the late 2010s, with diversity peaking in 2006. We identified three types of species interactions within the elasmobranch community: competition, predation, and ecosystem preference. The Scalloped hammerhead (Sphyrna lewini) and Whitetip reef (Triaenodon obesus) sharks were the main contributors to year-to-year variations in diversity. In addition, most species had a negative relationship with the co-occurrence of other elasmobranchs, underscoring the importance of potential competitive and predatory interactions. Our findings offer valuable insights for marine conservation efforts, particularly for understanding how interspecific interactions and ecological processes influence ecosystem stability over time. Our study provides a framework for future research on species co-occurrences in marine ecosystems, emphasizing the need for integrated, interaction-focused models that can better predict ecosystem responses to threats like overfishing and environmental change.
https://doi.org/10.32942/X2063T
Life Sciences
interspecific interactions, competition, ecological network, predation, ecological modeling, elasmobranchs, marine ecology, Eastern Tropical Pacific.
Published: 2025-05-08 07:16
Last Updated: 2025-05-13 07:48
CC-BY Attribution-NonCommercial-ShareAlike 4.0 International
Conflict of interest statement:
None
Data and Code Availability Statement:
https://github.com/Miguelbirostris/CocosElasmoNetwork2025
Language:
English
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