title: Recent Trends in Local-Scale Marine Biodiversity Reflect Community Structure and Human Impacts.
abstract: The modern biodiversity crisis reflects global extinctions and local introductions. Human activities have dramatically altered rates and scales of processes that regulate biodiversity at local scales. Reconciling the threat of global biodiversity loss with recent evidence of stability at fine spatial scales is a major challenge and requires a nuanced approach to biodiversity change that integrates ecological understanding. With a new dataset of 471 diversity time series spanning from 1962 to 2015 from marine coastal ecosystems, we tested (1) whether biodiversity changed at local scales in recent decades, and (2) whether we can ignore ecological context (e.g., proximate human impacts, trophic level, spatial scale) and still make informative inferences regarding local change. We detected a predominant signal of increasing species richness in coastal systems since 1962 in our dataset, though net species loss was associated with localized effects of anthropogenic impacts. Our geographically extensive dataset is unlikely to be a random sample of marine coastal habitats; impacted sites (3% of our time series) were underrepresented relative to their global presence. These local-scale patterns do not contradict the prospect of accelerating global extinctions but are consistent with local species loss in areas with direct human impacts and increases in diversity due to invasions and range expansions in lower impact areas. Attempts to detect and understand local biodiversity trends are incomplete without information on local human activities and ecological context.
authors.affiliation: Hopkins Marine Station, Stanford University, Pacific Grove, CA 93940, USA; Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. Electronic address: elahi@stanford.edu.
authors.forename: Robin
authors.initials: R
authors.lastname: Elahi
authors.affiliation: Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Mary I
authors.initials: MI
authors.lastname: O'Connor
authors.affiliation: Department of Biology, University of Massachusetts, Boston, MA 02125, USA.
authors.forename: Jarrett E K
authors.initials: JE
authors.lastname: Byrnes
authors.affiliation: Department of Biology, University of Massachusetts, Boston, MA 02125, USA.
authors.forename: Jillian
authors.initials: J
authors.lastname: Dunic
authors.affiliation: Department of Marine Benthic Ecology and Evolution, Centre for Ecological and Evolutionary Studies, University of Groningen, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
authors.forename: Britas Klemens
authors.initials: BK
authors.lastname: Eriksson
authors.affiliation: Department of Biology, University of Massachusetts, Boston, MA 02125, USA.
authors.forename: Marc J S
authors.initials: MJ
authors.lastname: Hensel
authors.affiliation: Department of Biology, University of Massachusetts, Boston, MA 02125, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Kearns
mesh_terms: D059001:Aquatic Organisms / Q000502:physiology*; D044822:Biodiversity; D003247:Conservation of Natural Resources; D008954:Models, Biological; D013997:Time Factors