Dataset: Parasite abundance in coral reef fishes

The loss of biological diversity is considered one of the principal environmental challenges of the 21st century, and there are hints that this massive reorganization of food webs could affect how parasites are transmitted among hosts. Parasites are often hidden and can be easy to overlook, but they are ecologically important and ubiquitous - so it is important to understand whether we should expect more or fewer of them as biodiversity disappears. Does biodiversity loss increase the abundance of parasites by eroding natural "checks and balances" on transmission? Or does it decrease parasite abundance by removing the free-living biodiversity on which parasites depend? Answers to these questions are urgently needed if we are to mitigate or prevent an uptick in parasite transmission for ecosystems experiencing biodiversity loss. In a joint collaborative research project among the University of Washington, Scripps Institution of Oceanography at UC San Diego, and California State University Monterey Bay, we created a parasite dataset of unprecedented size and taxonomic resolution. We sampled parasites of coral reef fishes from 19 replicate islands in the central equatorial Pacific to study how biodiversity and parasite burden covary. In this dataset, we present all of the data we collected on parasite abundance in coral reef fishes. We sampled 17 species (Acanthurus nigricans, Cephalopholis argus, Cephalopholis urodeta, Chromis iomelas, Chromis margaritifer, Ctenochaetus marginatus, Ctenochaetus striatus, Paracirrhites arcatus, Plectroglyphidodon dickii, Pseudanthias bartlettorum, Pseudanthias dispar, Pseudanthias mooreanus, Pseudanthias olivaceus, Pseudanthias pascalus, Pseudanthias spp., Stegastes aureus, Stegastes fasciolatus) across three archipelagos and 19 islands (Jarvis, Kingman, Kiritimati, Palmyra, Tabuaeran, and Teraina in the Northern Line Islands; Flint, Malden, Millennium, Starbuck, and Vostok in the Southern Line Islands; Huahine, Moorea, Raiatea, Rangiroa, Tahiti, Takapoto, Tetiaroa, and Tikehau in French Polynesia), for a total of 5,344 fish. These 17 broadly distributed host species represent a large spectrum of body sizes, including multiple taxonomic and trophic groups. Included in the dataset are specimens collected from expeditions mounted in 2009, 2010, 2011, 2013, 2019, 2020, and 2021. Fish were collected with three-pronged spears and hand-nets, individually labeled and bagged, and frozen for transport before being thawed and evaluated for parasites. Parasitological dissections were designed to detect all multi-cellular (i.e., metazoan) parasites other than myxozoans, but would not have detected viral, bacterial, protozoal, or fungal parasites. Parasites were identified to the lowest possible taxonomic level and grouped into their broad parasite taxonomic grouping (i.e., Acanthocephalan, Cestoda, Copepoda, Isopoda, Monogenea, Other Crustacea, Trematoda, Nematoda) and transmission strategy (i.e., complex life cycle versus direct transmission).