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Abstract
Sustaining biodiversity and ecosystems in the long term depends on their adjustment to a rapidly changing climate. By characterizing the structure of the marine plant eelgrass and associated communities at 50 sites across its broad range, we found that eelgrass growth form and biomass retain a legacy of Pleistocene range shifts and genetic bottlenecks that in turn affect the biomass of algae and invertebrates that fuel coastal food webs. The ecosystem-level effects of this ancient evolutionary legacy are comparable to or stronger than effects of current environmental forcing, suggesting that this economically important ecosystem may be unable to keep pace with rapid global change. Distribution of Earth’s biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate–trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth’s environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.
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Murphy GE, Dunic JC, Adamczyk EM, Bittick SJ, Côté IM, Cristiani J, Geissinger EA, Gregory RS, Lotze HK, O’Connor MI, Araújo CA, Rubidge EM, Templeman ND, Wong MC. From coast to coast to coast: ecology and management of seagrass ecosystems across Canada. Facets (Ott) 2021. [DOI: 10.1139/facets-2020-0020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Seagrass meadows are among the most productive and diverse marine ecosystems, providing essential structure, functions, and services. They are also among the most impacted by human activities and in urgent need of better management and protection. In Canada, eelgrass ( Zostera marina) meadows are found along the Atlantic, Pacific, and Arctic coasts, and thus occur across a wide range of biogeographic conditions. Here, we synthesize knowledge of eelgrass ecosystems across Canada’s coasts, highlighting commonalities and differences in environmental conditions, plant, habitat, and community structure, as well as current trends and human impacts. Across regions, eelgrass life history, phenology, and general species assemblages are similar. However, distinct regional differences occur in environmental conditions, particularly with water temperature and nutrient availability. There is considerable variation in the types and strengths of human activities among regions. The impacts of coastal development are prevalent in all regions, while other impacts are of concern for specific regions, e.g., nutrient loading in the Atlantic and impacts from the logging industry in the Pacific. In addition, climate change represents a growing threat to eelgrass meadows. We review current management and conservation efforts and discuss the implications of observed differences from coast to coast to coast.
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Affiliation(s)
- Grace E.P. Murphy
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
- Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
| | - Jillian C. Dunic
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Emily M. Adamczyk
- Department of Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Sarah J. Bittick
- Department of Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Isabelle M. Côté
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - John Cristiani
- Department of Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | | | - Robert S. Gregory
- Department of Biology, Memorial University, St. John’s, NL A1C 5S7, Canada
- Fisheries and Oceans Canada, St. John’s, NL A1A 5J7, Canada
| | - Heike K. Lotze
- Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Mary I. O’Connor
- Department of Zoology, Biodiversity Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Carlos A.S. Araújo
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC G5L 3A1, Canada
| | - Emily M. Rubidge
- Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC V8L 4B2, Canada
- Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | | | - Melisa C. Wong
- Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS B2Y 4A2, Canada
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