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A halo of reduced dinoflagellate abundances in and around eelgrass beds

TitleA halo of reduced dinoflagellate abundances in and around eelgrass beds
Publication TypeJournal Article
Year of Publication2020
AuthorsJacobs-Palmer E., Gallego R., Ramon-Laca A., Kunselman E., Cribari K., Horwith M., Kelly R.P
Date Published2020/04
Type of ArticleArticle
ISBN Number2167-8359
Accession NumberWOS:000524282000004
Keywordsalgal blooms; Allelopathy; biodiversity; density; Dinoflagellates; diversity; Eelgrass; Environmental DNA; Harmful algal bloom; oysters; puget-sound; sample; Science & Technology - Other Topics; seagrass ecosystems; shellfish toxins; Zostera marina; zostera-marina

Seagrass beds provide a variety of ecosystem services, both within and outside the bounds of the habitat itself. Here we use environmental DNA (eDNA) amplicons to analyze a broad cross-section of taxa from ecological communities in and immediately surrounding eelgrass (Zostera marina). Sampling seawater along transects extending alongshore outward from eelgrass beds, we demonstrate that eDNA provides meter-scale resolution of communities in the field. We evaluate eDNA abundance indices for 13 major phylogenetic groups of marine and estuarine taxa along these transects, finding highly local changes linked with proximity to Z. marina for a diverse group of dinoflagellates, and for no other group of taxa. Eelgrass habitat is consistently associated with dramatic reductions in dinoflagellate abundance both within the contiguous beds and for at least 15 m outside, relative to nearby sites without eelgrass. These results are consistent with the hypothesis that eelgrass-associated communities have allelopathic effects on dinoflagellates, and that these effects can extend in a halo beyond the bounds of the contiguous beds. Because many dinoflagellates are capable of forming harmful algal blooms (HABs) toxic to humans and other animal species, the apparent salutary effect of eelgrass habitat on neighboring waters has important implications for public health as well as shellfish aquaculture and harvesting.

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