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Krumhansl KA, Brooks CM, Lowen JB, O’Brien JM, Wong MC, DiBacco C. Loss, resilience and recovery of kelp forests in a region of rapid ocean warming. Ann Bot 2024; 133:73-92. [PMID: 37952103 PMCID: PMC10921841 DOI: 10.1093/aob/mcad170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 11/08/2023] [Indexed: 11/14/2023]
Abstract
BACKGROUND AND AIMS Changes in kelp abundances on regional scales have been highly variable over the past half-century owing to strong effects of local and regional drivers. Here, we assess patterns and dominant environmental variables causing spatial and interspecific variability in kelp persistence and resilience to change in Nova Scotia over the past 40 years. METHODS We conducted a survey of macrophyte abundance at 251 sites spanning the Atlantic coast of Nova Scotia from 2019 to 2022. We use this dataset to describe spatial variability in kelp species abundances, compare species occurrences to surveys conducted in 1982 and assess changes in kelp abundance over the past 22 years. We then relate spatial and temporal patterns in abundance and resilience to environmental metrics. KEY RESULTS Our results show losses of sea urchins and the cold-tolerant kelp species Alaria esculenta, Saccorhiza dermatodea and Agarum clathratum in Nova Scotia since 1982 in favour of the more warm-tolerant kelps Saccharina latissima and Laminaria digitata. Kelp abundances have increased slightly since 2000, and Saccharina latissima and L. digitata are widely abundant in the region today. The highest kelp cover occurs on wave-exposed shores and at sites where temperatures have remained below thresholds for growth (21 °C) and mortality (23 °C). Moreover, kelp has recovered from turf dominance following losses at some sites during a warm period from 2010 to 2012. CONCLUSIONS Our results indicate that dramatic changes in kelp community composition and a loss of sea urchin herbivory as a dominant driver of change in the system have occurred in Nova Scotia over the past 40 years. However, a broad-scale shift to turf-dominance has not occurred, as predicted, and our results suggest that resilience and persistence are still a feature of kelp forests in the region despite rapid warming over the past several decades.
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Affiliation(s)
- K A Krumhansl
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - C M Brooks
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - J B Lowen
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - J M O’Brien
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - M C Wong
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
| | - C DiBacco
- Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, B2Y 4A2, Canada
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Hanley ME, Firth LB, Foggo A. Victim of changes? Marine macroalgae in a changing world. Ann Bot 2024; 133:1-16. [PMID: 37996092 PMCID: PMC10921835 DOI: 10.1093/aob/mcad185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 11/25/2023]
Abstract
BACKGROUND Marine macroalgae ('seaweeds') are a diverse and globally distributed group of photosynthetic organisms that together generate considerable primary productivity, provide an array of different habitats for other organisms, and contribute many important ecosystem functions and services. As a result of continued anthropogenic stress on marine systems, many macroalgal species and habitats face an uncertain future, risking their vital contribution to global productivity and ecosystem service provision. SCOPE After briefly considering the remarkable taxonomy and ecological distribution of marine macroalgae, we review how the threats posed by a combination of anthropogenically induced stressors affect seaweed species and communities. From there we highlight five critical avenues for further research to explore (long-term monitoring, use of functional traits, focus on early ontogeny, biotic interactions and impact of marine litter on coastal vegetation). CONCLUSIONS Although there are considerable parallels with terrestrial vascular plant responses to the many threats posed by anthropogenic stressors, we note that the impacts of some (e.g. habitat loss) are much less keenly felt in the oceans than on land. Nevertheless, and in common with terrestrial plant communities, the impact of climate change will inevitably be the most pernicious threat to the future persistence of seaweed species, communities and service provision. While understanding macroalgal responses to simultaneous environmental stressors is inevitably a complex exercise, our attempt to highlight synergies with terrestrial systems, and provide five future research priorities to elucidate some of the important trends and mechanisms of response, may yet offer some small contribution to this goal.
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Affiliation(s)
- Mick E Hanley
- School of Biological and Marine Sciences, University of Plymouth, UK
| | - Louise B Firth
- School of Biological and Marine Sciences, University of Plymouth, UK
| | - Andy Foggo
- School of Biological and Marine Sciences, University of Plymouth, UK
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Hollarsmith JA, Cornett JC, Evenson E, Tugaw A. A century of canopy kelp persistence and recovery in the Gulf of Alaska. Ann Bot 2024; 133:105-116. [PMID: 37832150 PMCID: PMC10921840 DOI: 10.1093/aob/mcad149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 10/12/2023] [Indexed: 10/15/2023]
Abstract
BACKGROUND AND AIMS Coastal Alaska contains vast kelp habitat that supports diverse marine and human communities. Over the past century, the North Pacific Ocean has undergone oceanographic and ecological regime shifts that have the potential to influence the structure and function of kelp ecosystems strongly. However, the remoteness and complexity of the glacially carved region precludes the regular monitoring efforts that would be necessary to detect such changes. METHODS To begin to fill this critical knowledge gap, we drew upon historical and modern surveys to analyse the change in spatial coverage and species composition of canopy kelp between two time points (1913 and the early 2000s to 2010s). We also incorporated decadal surveys on sea otter range expansion following complete extirpation and reintroduction to assess the influence of sea otter recovery on the spatial extent of canopy kelp. KEY RESULTS We found increases in the spatial extent of canopy kelp throughout the Gulf of Alaska where there was coverage from both surveys. Kelp in Southcentral Alaska showed extensive recovery after the catastrophic Novarupta volcano. Kelp in Southeast Alaska showed persistence and spatial increase that closely matched increases in the range of sea otters. Observations of thermally tolerant kelp species increased more than observations of cold-adapted species between the two surveys. CONCLUSIONS Contrary to trends observed at lower latitudes, the kelp forests that ring the Gulf of Alaska have been remarkably stable and even increased in the past century, despite oceanographic and ecosystem changes. To improve monitoring, we propose identification of sentinel kelp beds for regular monitoring to detect changes to these iconic and foundational canopy kelp species more readily.
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Affiliation(s)
- Jordan A Hollarsmith
- NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, 17109 Point Lena Loop Road, Juneau, AK 99801, USA
| | - Juliana C Cornett
- NOAA, National Marine Fisheries Service, Alaska Fisheries Science Center, 17109 Point Lena Loop Road, Juneau, AK 99801, USA
- Alaska Sea Grant, University of Alaska Fairbanks, 218 O’Neill Building, PO Box 755040, Fairbanks, AK 99775, USA
| | - Emily Evenson
- Washington State University, 1815 Wilson Road, Pullman, WA 99163, USA
- Cooperative Institute for Climate, Ocean, & Ecosystem Studies, University of Washington, 3737 Brooklyn Avenue NE, Seattle, WA 98105, USA and
| | - Alex Tugaw
- University of Alaska Southeast, 11066 Auke Lake Way, Juneau, AK 99801, USA
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Wernberg T, Thomsen MS, Baum JK, Bishop MJ, Bruno JF, Coleman MA, Filbee-Dexter K, Gagnon K, He Q, Murdiyarso D, Rogers K, Silliman BR, Smale DA, Starko S, Vanderklift MA. Impacts of Climate Change on Marine Foundation Species. Ann Rev Mar Sci 2024; 16:247-282. [PMID: 37683273 DOI: 10.1146/annurev-marine-042023-093037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
Marine foundation species are the biotic basis for many of the world's coastal ecosystems, providing structural habitat, food, and protection for myriad plants and animals as well as many ecosystem services. However, climate change poses a significant threat to foundation species and the ecosystems they support. We review the impacts of climate change on common marine foundation species, including corals, kelps, seagrasses, salt marsh plants, mangroves, and bivalves. It is evident that marine foundation species have already been severely impacted by several climate change drivers, often through interactive effects with other human stressors, such as pollution, overfishing, and coastal development. Despite considerable variation in geographical, environmental, and ecological contexts, direct and indirect effects of gradual warming and subsequent heatwaves have emerged as the most pervasive drivers of observed impact and potent threat across all marine foundation species, but effects from sea level rise, ocean acidification, and increased storminess are expected to increase. Documented impacts include changes in the genetic structures, physiology, abundance, and distribution of the foundation species themselves and changes to their interactions with other species, with flow-on effects to associated communities, biodiversity, and ecosystem functioning. We discuss strategies to support marine foundation species into the Anthropocene, in order to increase their resilience and ensure the persistence of the ecosystem services they provide.
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Affiliation(s)
- Thomas Wernberg
- Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia;
- Flødevigen Research Station, Institute of Marine Research, His, Norway
| | - Mads S Thomsen
- Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Ecoscience, Aarhus University, Roskilde, Denmark
| | - Julia K Baum
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Melanie J Bishop
- School of Natural Sciences, Macquarie University, Macquarie Park, New South Wales, Australia
| | - John F Bruno
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Melinda A Coleman
- National Marine Science Centre, New South Wales Department of Primary Industries, Coffs Harbour, New South Wales, Australia
| | - Karen Filbee-Dexter
- Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia;
- Flødevigen Research Station, Institute of Marine Research, His, Norway
| | - Karine Gagnon
- Flødevigen Research Station, Institute of Marine Research, His, Norway
| | - Qiang He
- Coastal Ecology Lab, MOE Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Daniel Murdiyarso
- Center for International Forestry Research-World Agroforestry (CIFOR-ICRAF), Bogor, Indonesia
- Department of Geophysics and Meteorology, IPB University, Bogor, Indonesia
| | - Kerrylee Rogers
- School of Earth, Atmospheric, and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - Brian R Silliman
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Dan A Smale
- Marine Biological Association of the United Kingdom, Plymouth, United Kingdom
| | - Samuel Starko
- Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia;
| | - Mathew A Vanderklift
- Indian Ocean Marine Research Centre, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Crawley, Western Australia, Australia
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Weigel BL, Small SL, Berry HD, Dethier MN. Effects of temperature and nutrients on microscopic stages of the bull kelp (Nereocystis luetkeana, Phaeophyceae). J Phycol 2023; 59:893-907. [PMID: 37497792 DOI: 10.1111/jpy.13366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/23/2023] [Accepted: 06/27/2023] [Indexed: 07/28/2023]
Abstract
Warming ocean temperatures have been linked to kelp forest declines worldwide, and elevated temperatures can act synergistically with other local stressors to exacerbate kelp loss. The bull kelp Nereocystis luetkeana is the primary canopy-forming kelp species in the Salish Sea, where it is declining in areas with elevated summer water temperatures and low nutrient concentrations. To determine the interactive effects of these two stressors on microscopic stages of N. luetkeana, we cultured gametophytes and microscopic sporophytes from seven different Salish Sea populations across seven different temperatures (10-22°C) and two nitrogen concentrations. The thermal tolerance of microscopic gametophytes and sporophytes was similar across populations, and high temperatures were more stressful than low nitrogen levels. Additional nitrogen did not improve gametophyte or sporophyte survival at high temperatures. Gametophyte densities were highest between 10 and 16°C and declined sharply at 18°C, and temperatures of 20 and 22°C were lethal. The window for successful sporophyte production was narrower, peaking at 10-14°C. Across all populations, the warmest temperature at which sporophytes were produced was 16 or 18°C, but sporophyte densities were 78% lower at 16°C and 95% lower at 18°C compared to cooler temperatures. In the field, bottom temperatures revealed that the thermal limits of gametophyte growth (18°C) and sporophyte production (16-18°C) were reached during the summer at multiple sites. Prolonged exposure of bull kelp gametophytes to temperatures of 16°C and above could limit reproduction, and therefore recruitment, of adult kelp sporophytes.
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Affiliation(s)
- Brooke L Weigel
- Friday Harbor Labs, University of Washington, Friday Harbor, Washington, USA
| | - Sadie L Small
- Friday Harbor Labs, University of Washington, Friday Harbor, Washington, USA
| | - Helen D Berry
- Washington State Department of Natural Resources, Olympia, Washington, USA
| | - Megan N Dethier
- Friday Harbor Labs, University of Washington, Friday Harbor, Washington, USA
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Wear B, O'Connor NE, Schmid MJ, Jackson MC. What does the future look like for kelp when facing multiple stressors? Ecol Evol 2023; 13:e10203. [PMID: 37384243 PMCID: PMC10293785 DOI: 10.1002/ece3.10203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 05/26/2023] [Accepted: 05/30/2023] [Indexed: 06/30/2023] Open
Abstract
As primary producers and ecosystem engineers, kelp (generally Order Laminariales) are ecologically important, and their decline could have far-reaching consequences. Kelp are valuable in forming habitats for fish and invertebrates and are crucial for adaptation to climate change by creating coastal defenses and in providing key functions, such as carbon sequestration and food provision. Kelp are threatened by multiple stressors, such as climate change, over-harvesting of predators, and pollution. In this opinion paper, we discuss how these stressors may interact to affect kelp, and how this varies under different contexts. We argue that more research that bridges kelp conservation and multiple stressor theory is needed and outline key questions that should be addressed as a priority. For instance, it is important to understand how previous exposure (either to earlier generations or life stages) determines responses to emerging stressors, and how responses in kelp scale up to alter food webs and ecosystem functioning. By increasing the temporal and biological complexity of kelp research in this way, we will improve our understanding allowing better predictions. This research is essential for the effective conservation and potential restoration of kelp in our rapidly changing world.
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Affiliation(s)
- Brigitte Wear
- Department of BiologyUniversity of OxfordOxfordUK
- Somerville CollegeOxfordUK
| | - Nessa E. O'Connor
- School of Natural Sciences, Discipline of ZoologyTrinity College DublinDublinIreland
| | - Matthias J. Schmid
- School of Natural Sciences, Discipline of ZoologyTrinity College DublinDublinIreland
- School of Natural ScienceUniversity of GalwayGalwayIreland
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Ulaski BP, Sikes DS, Konar B. Beach-cast and drifting seaweed wrack is an important resource for marine and terrestrial macroinvertebrates in high latitudes. Mar Environ Res 2023; 187:105970. [PMID: 37004498 DOI: 10.1016/j.marenvres.2023.105970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/22/2023] [Accepted: 03/26/2023] [Indexed: 06/19/2023]
Abstract
Seaweeds are foundation species across near-subtidal and intertidal zones, including when detached and free-floating and then cast ashore as wrack. Wrack is sometimes removed by humans for aesthetics or to be used as fertilizer. The study of wrack as an important habitat and resource for macroinvertebrates in high latitudes has been limited. To determine which taxa might be impacted when wrack is removed, the composition and relative abundance of macroinvertebrates were quantified monthly and compared in areas with and without wrack in Kachemak Bay, Alaska. Relationships were assessed between macroinvertebrates and wrack line (tidal height, moisture content, seaweed biomass) and beach characteristics (wave exposure, beach slope, substrate types). Approximately 47,000 animals were counted and a total of 87 taxa were identified from beach-cast wrack, drifting wrack, and bare sediment habitats. Macroinvertebrate communities within beach-cast wrack and bare sediment habitats were significantly different. Beach-cast wrack generally had more terrestrially-derived animals, especially Coleoptera and Diptera. Bare beach sediment was predominantly occupied by Enchytraeida (annelids). Macroinvertebrate communities were most strongly influenced by seaweed biomass and tidal height of the wrack line. Beach-cast wrack and bare sediments were also compared to drifting wrack in shallow, nearshore waters. Drifting wrack was different and generally occupied by more marine-derived animals, especially Amphipoda, Gastropoda, Mytilida, and Polychaeta. Ecological succession in decaying beach-cast wrack was documented, with decomposers (e.g., Amphipoda and Diptera) being early colonizers, and predators (e.g., Coleoptera and Hymenoptera) arriving later. Understanding the importance of this unique and ecologically important habitat to macroinvertebrates is essential, as removals and reductions in wrack availability could influence macroinvertebrate community structure, higher trophic level consumers, and key ecological processes on beaches. This study is the first direct investigation into seaweed wrack-associated macroinvertebrate communities in a sub-Arctic system.
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Affiliation(s)
- Brian P Ulaski
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, P.O. Box 757220, Fairbanks, AK, 99775-7220, USA.
| | - Derek S Sikes
- University of Alaska Museum, Department of Biology & Wildlife, University of Alaska Fairbanks, 1962 Yukon Drive, Fairbanks, AK, 99775-6960, USA
| | - Brenda Konar
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, P.O. Box 757220, Fairbanks, AK, 99775-7220, USA
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Whalen MA, Starko S, Lindstrom SC, Martone PT. Heatwave restructures marine intertidal communities across a stress gradient. Ecology 2023; 104:e4027. [PMID: 36897574 DOI: 10.1002/ecy.4027] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 01/11/2023] [Accepted: 02/13/2023] [Indexed: 03/11/2023]
Abstract
Significant questions remain about how ecosystems that are structured by abiotic stress will be affected by climate change. Warmer temperatures are hypothesized to shift species along abiotic gradients such that distributions track changing environments where physical conditions allow. However, community-scale impacts of extreme warming in heterogeneous landscapes are likely to be more complex. We investigated the impacts of a multiyear marine heatwave on intertidal community dynamics and zonation on a wave-swept rocky coastline along the Central Coast of British Columbia, Canada. Leveraging an 8-year time series with high seaweed taxonomic resolution (116 taxa) that was established 3 years prior to the heatwave, we document major shifts in zonation and abundance of populations that led to substantial reorganization at the community level. The heatwave was associated with shifts in primary production away from upper elevations through declines in seaweed cover and partial replacement by invertebrates. At low elevations, seaweed cover remained stable or recovered rapidly following decline, being balanced by increases in some species and decreases in others. These results illustrate that, rather than shifting community zonation uniformly along abiotic stress gradients, intense and lasting warming events may restructure patterns of ecological dominance and reduce total habitability of ecosystems, especially at extreme ends of pre-existing abiotic gradients.
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Affiliation(s)
- Matthew A Whalen
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Hakai Institute, End of Kwakshua Channel, Calvert Island, BC, Canada
| | - Samuel Starko
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- UWA Ocean Institute and School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, WA, 6009, Australia
| | - Sandra C Lindstrom
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Hakai Institute, End of Kwakshua Channel, Calvert Island, BC, Canada
| | - Patrick T Martone
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Hakai Institute, End of Kwakshua Channel, Calvert Island, BC, Canada
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