1
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Hildebrand L, Derville S, Hildebrand I, Torres LG. Exploring indirect effects of a classic trophic cascade between urchins and kelp on zooplankton and whales. Sci Rep 2024; 14:9815. [PMID: 38684814 PMCID: PMC11059377 DOI: 10.1038/s41598-024-59964-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 04/17/2024] [Indexed: 05/02/2024] Open
Abstract
Kelp forest trophic cascades have been extensively researched, yet indirect effects to the zooplankton prey base and gray whales have not been explored. We investigate the correlative patterns of a trophic cascade between bull kelp and purple sea urchins on gray whales and zooplankton in Oregon, USA. Using generalized additive models (GAMs), we assess (1) temporal dynamics of the four species across 8 years, and (2) possible trophic paths from urchins to kelp, kelp as habitat to zooplankton, and kelp and zooplankton to gray whales. Temporal GAMs revealed an increase in urchin coverage, with simultaneous decline in kelp condition, zooplankton abundance and gray whale foraging time. Trophic path GAMs, which tested for correlations between species, demonstrated that urchins and kelp were negatively correlated, while kelp and zooplankton were positively correlated. Gray whales showed nuanced and site-specific correlations with zooplankton in one site, and positive correlations with kelp condition in both sites. The negative correlation between the kelp-urchin trophic cascade and zooplankton resulted in a reduced prey base for gray whales. This research provides a new perspective on the vital role kelp forests may play across multiple trophic levels and interspecies linkages.
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Affiliation(s)
- Lisa Hildebrand
- Geospatial Ecology of Marine Megafauna Laboratory, Department of Fisheries, Wildlife & Conservation Sciences, Marine Mammal Institute, Oregon State University, Newport, OR, USA.
| | - Solène Derville
- Geospatial Ecology of Marine Megafauna Laboratory, Department of Fisheries, Wildlife & Conservation Sciences, Marine Mammal Institute, Oregon State University, Newport, OR, USA
- UMR ENTROPIE (IRD-Université de La Réunion-CNRS-Laboratoire d'excellence LabEx-CORAIL), Nouméa, New Caledonia
| | - Ines Hildebrand
- Geospatial Ecology of Marine Megafauna Laboratory, Department of Fisheries, Wildlife & Conservation Sciences, Marine Mammal Institute, Oregon State University, Newport, OR, USA
| | - Leigh G Torres
- Geospatial Ecology of Marine Megafauna Laboratory, Department of Fisheries, Wildlife & Conservation Sciences, Marine Mammal Institute, Oregon State University, Newport, OR, USA
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2
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Korabik AR, Winquist T, Grosholz ED, Hollarsmith JA. Examining the reproductive success of bull kelp (Nereocystis luetkeana, Phaeophyceae, Laminariales) in climate change conditions. JOURNAL OF PHYCOLOGY 2023; 59:989-1004. [PMID: 37540062 DOI: 10.1111/jpy.13368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 05/23/2023] [Accepted: 05/29/2023] [Indexed: 08/05/2023]
Abstract
Climate change is affecting marine ecosystems in many ways, including raising temperatures and leading to ocean acidification. From 2014 to 2016, an extensive marine heat wave extended along the west coast of North America and had devastating effects on numerous species, including bull kelp (Nereocystis luetkeana). Bull kelp is an important foundation species in coastal ecosystems and can be affected by marine heat waves and ocean acidification; however, the impacts have not been investigated on sensitive early life stages. To determine the effects of changing temperatures and carbonate levels on Northern California's bull kelp populations, we collected sporophylls from mature bull kelp individuals in Point Arena, CA. At the Bodega Marine Laboratory, we released spores from field-collected bull kelp, and cultured microscopic gametophytes in a common garden experiment with a fully factorial design crossing modern conditions (11.63 ± 0.54°C and pH 7.93 ± 0.26) with observed extreme climate conditions (15.56 ± 0.83°C and 7.64 ± 0.32 pH). Our results indicated that both increased temperature and decreased pH influenced growth and egg production of bull kelp microscopic stages. Increased temperature resulted in decreased gametophyte survival and offspring production. In contrast, decreased pH had less of an effect but resulted in increased gametophyte survival and offspring production. Additionally, increased temperature significantly impacted reproductive timing by causing female gametophytes to produce offspring earlier than under ambient temperature conditions. Our findings can inform better predictions of the impacts of climate change on coastal ecosystems and provide key insights into environmental dynamics regulating the bull kelp lifecycle.
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Affiliation(s)
- Angela R Korabik
- Department of Environmental Science and Policy, University of California Davis, Davis, California, USA
| | - Tallulah Winquist
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Edwin D Grosholz
- Department of Environmental Science and Policy, University of California Davis, Davis, California, USA
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3
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Bell TW, Cavanaugh KC, Saccomanno VR, Cavanaugh KC, Houskeeper HF, Eddy N, Schuetzenmeister F, Rindlaub N, Gleason M. Kelpwatch: A new visualization and analysis tool to explore kelp canopy dynamics reveals variable response to and recovery from marine heatwaves. PLoS One 2023; 18:e0271477. [PMID: 36952444 PMCID: PMC10035835 DOI: 10.1371/journal.pone.0271477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 03/03/2023] [Indexed: 03/25/2023] Open
Abstract
Giant kelp and bull kelp forests are increasingly at risk from marine heatwave events, herbivore outbreaks, and the loss or alterations in the behavior of key herbivore predators. The dynamic floating canopy of these kelps is well-suited to study via satellite imagery, which provides high temporal and spatial resolution data of floating kelp canopy across the western United States and Mexico. However, the size and complexity of the satellite image dataset has made ecological analysis difficult for scientists and managers. To increase accessibility of this rich dataset, we created Kelpwatch, a web-based visualization and analysis tool. This tool allows researchers and managers to quantify kelp forest change in response to disturbances, assess historical trends, and allow for effective and actionable kelp forest management. Here, we demonstrate how Kelpwatch can be used to analyze long-term trends in kelp canopy across regions, quantify spatial variability in the response to and recovery from the 2014 to 2016 marine heatwave events, and provide a local analysis of kelp canopy status around the Monterey Peninsula, California. We found that 18.6% of regional sites displayed a significant trend in kelp canopy area over the past 38 years and that there was a latitudinal response to heatwave events for each kelp species. The recovery from heatwave events was more variable across space, with some local areas like Bahía Tortugas in Baja California Sur showing high recovery while kelp canopies around the Monterey Peninsula continued a slow decline and patchy recovery compared to the rest of the Central California region. Kelpwatch provides near real time spatial data and analysis support and makes complex earth observation data actionable for scientists and managers, which can help identify areas for research, monitoring, and management efforts.
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Affiliation(s)
- Tom W. Bell
- Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | - Kyle C. Cavanaugh
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
| | | | - Katherine C. Cavanaugh
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
| | - Henry F. Houskeeper
- Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
| | - Norah Eddy
- The Nature Conservancy, Sacramento, California, United States of America
| | | | - Nathaniel Rindlaub
- The Nature Conservancy, Sacramento, California, United States of America
| | - Mary Gleason
- The Nature Conservancy, Sacramento, California, United States of America
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4
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Carlson DF, Vivó-Pons A, Treier UA, Mätzler E, Meire L, Sejr M, Krause-Jensen D. Mapping intertidal macrophytes in fjords in Southwest Greenland using Sentinel-2 imagery. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 865:161213. [PMID: 36584947 DOI: 10.1016/j.scitotenv.2022.161213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 12/20/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Changes in the distribution of coastal macrophytes in Greenland, and elsewhere in the Arctic are difficult to quantify as the region remains challenging to access and monitor. Satellite imagery, in particular Sentinel-2 (S2), may enable large-scale monitoring of coastal areas in Greenland but its use is impacted by the optically complex environments and the scarcity of supporting data in the region. Additionally, the canopies of the dominant macrophyte species in Greenland do not extend to the sea surface, limiting the use of indices that exploit the reflection of near-infrared radiation by vegetation due to its absorption by seawater. Three hypotheses are tested: I) 10-m S2 imagery and commonly used detection methods can identify intertidal macrophytes that are exposed at low tide in an optically complex fjord system in Greenland impacted by marine and land terminating glaciers; II) detached and floating macrophytes accumulate in patches that are sufficiently large to be detected by 10-m S2 images; III) iceberg scour and/or turbid meltwater runoff shape the spatial distribution of intertidal macroalgae in fjord systems with marine-terminating glaciers. The NDVI produced the best results in optically complex fjord systems in Greenland. 12 km2 of exposed intertidal macrophytes were identified in the study area at low tide. Floating mats of macrophytes ranged in area from 400 m2 to 326,800 m2 and were most common at the mouth of the fjord. Icebergs and turbidity appear to play a role in structuring the distribution of intertidal macrophytes and the retreat of marine terminating glaciers could allow macrophytes cover to expand. The challenges and solutions presented here apply to most fjords in Greenland and, therefore, the methodology may be extended to produce a Greenland-wide estimate of intertidal macrophytes.
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Affiliation(s)
- Daniel F Carlson
- Arctic Research Centre, Aarhus University, Ole Worms Allé 1, Aarhus 8000, Denmark; Optical Oceanography, Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Max-Planck Str. 1, 21502 Geesthacht, Germany.
| | - Antoni Vivó-Pons
- Arctic Research Centre, Aarhus University, Ole Worms Allé 1, Aarhus 8000, Denmark; Centre for Ocean Life, National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet, Lyngby 2800, Denmark
| | - Urs A Treier
- Department of Biology, Ecoinformatics and Biodiversity, Aarhus University, Ny Munkegade 116, Aarhus 8000, Denmark
| | | | - Lorenz Meire
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Kivioq 2, Nuuk 3900, Greenland; Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, Yerseke, the Netherlands
| | - Mikael Sejr
- Arctic Research Centre, Aarhus University, Ole Worms Allé 1, Aarhus 8000, Denmark; Department of Ecoscience, Marine Ecology, Aarhus University, C.F. Møllers Allé, Building 1131, 8000 Aarhus C, Denmark
| | - Dorte Krause-Jensen
- Arctic Research Centre, Aarhus University, Ole Worms Allé 1, Aarhus 8000, Denmark; Department of Ecoscience, Marine Ecology, Aarhus University, C.F. Møllers Allé, Building 1131, 8000 Aarhus C, Denmark
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5
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Galloway AWE, Gravem SA, Kobelt JN, Heady WN, Okamoto DK, Sivitilli DM, Saccomanno VR, Hodin J, Whippo R. Sunflower sea star predation on urchins can facilitate kelp forest recovery. Proc Biol Sci 2023; 290:20221897. [PMID: 36809801 PMCID: PMC9943640 DOI: 10.1098/rspb.2022.1897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 01/25/2023] [Indexed: 02/23/2023] Open
Abstract
The recent collapse of predatory sunflower sea stars (Pycnopodia helianthoides) owing to sea star wasting disease (SSWD) is hypothesized to have contributed to proliferation of sea urchin barrens and losses of kelp forests on the North American west coast. We used experiments and a model to test whether restored Pycnopodia populations may help recover kelp forests through their consumption of nutritionally poor purple sea urchins (Strongylocentrotus purpuratus) typical of barrens. Pycnopodia consumed 0.68 S. purpuratus d-1, and our model and sensitivity analysis shows that the magnitude of recent Pycnopodia declines is consistent with urchin proliferation after modest sea urchin recruitment, and even small Pycnopodia recoveries could generally lead to lower densities of sea urchins that are consistent with kelp-urchin coexistence. Pycnopodia seem unable to chemically distinguish starved from fed urchins and indeed have higher predation rates on starved urchins owing to shorter handling times. These results highlight the importance of Pycnopodia in regulating purple sea urchin populations and maintaining healthy kelp forests through top-down control. The recovery of this important predator to densities commonly found prior to SSWD, whether through natural means or human-assisted reintroductions, may therefore be a key step in kelp forest restoration at ecologically significant scales.
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Affiliation(s)
- A. W. E. Galloway
- Oregon Institute of Marine Biology, Department of Biology, University of Oregon, 63466 Boat Basin Road, Charleston OR 97420, USA
| | - S. A. Gravem
- Department of Integrative Biology and Partnership for Interdisciplinary Studies of Coastal Oceans, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
| | - J. N. Kobelt
- School of Aquatic and Fishery Sciences, University of Washington, 98195, Seattle WA, USA
| | - W. N. Heady
- The Nature Conservancy, Sacramento CA, 95811, USA
| | - D. K. Okamoto
- Department of Biological Science, Florida State University, Tallahassee, 32306 FL, USA
| | - D. M. Sivitilli
- Astrobiology Program, University of Washington, 98195, Seattle WA, USA
- Department of Psychology, University of Washington, 98195, Seattle WA, USA
| | | | - J. Hodin
- Friday Harbor Laboratories, University of Washington, 98195, Seattle WA, USA
| | - R. Whippo
- Oregon Institute of Marine Biology, Department of Biology, University of Oregon, 63466 Boat Basin Road, Charleston OR 97420, USA
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6
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Marquez L, Fragkopoulou E, Cavanaugh KC, Houskeeper HF, Assis J. Artificial intelligence convolutional neural networks map giant kelp forests from satellite imagery. Sci Rep 2022; 12:22196. [PMID: 36564409 PMCID: PMC9789120 DOI: 10.1038/s41598-022-26439-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
Climate change is producing shifts in the distribution and abundance of marine species. Such is the case of kelp forests, important marine ecosystem-structuring species whose distributional range limits have been shifting worldwide. Synthesizing long-term time series of kelp forest observations is therefore vital for understanding the drivers shaping ecosystem dynamics and for predicting responses to ongoing and future climate changes. Traditional methods of mapping kelp from satellite imagery are time-consuming and expensive, as they require high amount of human effort for image processing and algorithm optimization. Here we propose the use of mask region-based convolutional neural networks (Mask R-CNN) to automatically assimilate data from open-source satellite imagery (Landsat Thematic Mapper) and detect kelp forest canopy cover. The analyses focused on the giant kelp Macrocystis pyrifera along the shorelines of southern California and Baja California in the northeastern Pacific. Model hyper-parameterization was tuned through cross-validation procedures testing the effect of data augmentation, and different learning rates and anchor sizes. The optimal model detected kelp forests with high performance and low levels of overprediction (Jaccard's index: 0.87 ± 0.07; Dice index: 0.93 ± 0.04; over prediction: 0.06) and allowed reconstructing a time series of 32 years in Baja California (Mexico), a region known for its high variability in kelp owing to El Niño events. The proposed framework based on Mask R-CNN now joins the list of cost-efficient tools for long-term marine ecological monitoring, facilitating well-informed biodiversity conservation, management and decision making.
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Affiliation(s)
- L Marquez
- CCMAR - Center of Marine Sciences, University of the Algarve, 8005-139, Faro, Portugal
| | - E Fragkopoulou
- CCMAR - Center of Marine Sciences, University of the Algarve, 8005-139, Faro, Portugal
| | - K C Cavanaugh
- Department of Geography, University of California, Los Angeles, CA, USA
| | - H F Houskeeper
- Department of Geography, University of California, Los Angeles, CA, USA
| | - J Assis
- CCMAR - Center of Marine Sciences, University of the Algarve, 8005-139, Faro, Portugal.
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7
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Hyndes GA, Berdan EL, Duarte C, Dugan JE, Emery KA, Hambäck PA, Henderson CJ, Hubbard DM, Lastra M, Mateo MA, Olds A, Schlacher TA. The role of inputs of marine wrack and carrion in sandy-beach ecosystems: a global review. Biol Rev Camb Philos Soc 2022; 97:2127-2161. [PMID: 35950352 PMCID: PMC9804821 DOI: 10.1111/brv.12886] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 01/09/2023]
Abstract
Sandy beaches are iconic interfaces that functionally link the ocean with the land via the flow of organic matter from the sea. These cross-ecosystem fluxes often comprise uprooted seagrass and dislodged macroalgae that can form substantial accumulations of detritus, termed 'wrack', on sandy beaches. In addition, the tissue of the carcasses of marine animals that regularly wash up on beaches form a rich food source ('carrion') for a diversity of scavenging animals. Here, we provide a global review of how wrack and carrion provide spatial subsidies that shape the structure and functioning of sandy-beach ecosystems (sandy beaches and adjacent surf zones), which typically have little in situ primary production. We also examine the spatial scaling of the influence of these processes across the broader land- and seascape, and identify key gaps in our knowledge to guide future research directions and priorities. Large quantities of detrital kelp and seagrass can flow into sandy-beach ecosystems, where microbial decomposers and animals process it. The rates of wrack supply and its retention are influenced by the oceanographic processes that transport it, the geomorphology and landscape context of the recipient beaches, and the condition, life history and morphological characteristics of the macrophyte taxa that are the ultimate source of wrack. When retained in beach ecosystems, wrack often creates hotspots of microbial metabolism, secondary productivity, biodiversity, and nutrient remineralization. Nutrients are produced during wrack breakdown, and these can return to coastal waters in surface flows (swash) and aquifers discharging into the subtidal surf. Beach-cast kelp often plays a key trophic role, being an abundant and preferred food source for mobile, semi-aquatic invertebrates that channel imported algal matter to predatory invertebrates, fish, and birds. The role of beach-cast marine carrion is likely to be underestimated, as it can be consumed rapidly by highly mobile scavengers (e.g. foxes, coyotes, raptors, vultures). These consumers become important vectors in transferring marine productivity inland, thereby linking marine and terrestrial ecosystems. Whilst deposits of organic matter on sandy-beach ecosystems underpin a range of ecosystem functions and services, they can be at variance with aesthetic perceptions resulting in widespread activities, such as 'beach cleaning and grooming'. This practice diminishes the energetic base of food webs, intertidal fauna, and biodiversity. Global declines in seagrass beds and kelp forests (linked to global warming) are predicted to cause substantial reductions in the amounts of marine organic matter reaching many beach ecosystems, likely causing flow-on effects for food webs and biodiversity. Similarly, future sea-level rise and increased storm frequency are likely to alter profoundly the physical attributes of beaches, which in turn can change the rates at which beaches retain and process the influxes of wrack and animal carcasses. Conservation of the multi-faceted ecosystem services that sandy beaches provide will increasingly need to encompass a greater societal appreciation and the safeguarding of ecological functions reliant on beach-cast organic matter on innumerable ocean shores worldwide.
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Affiliation(s)
- Glenn A. Hyndes
- Centre for Marine Ecosystems Research, School of ScienceEdith Cowan UniversityJoondalupWestern AustraliaAustralia
| | - Emma L. Berdan
- Department of Marine SciencesUniversity of GothenburgGöteborgSweden
| | - Cristian Duarte
- Departamento de Ecología y Biodiversidad, Facultad de Ciencias de la VidaUniversidad Andres BelloSantiagoChile
| | - Jenifer E. Dugan
- Marine Science InstituteUniversity of CaliforniaSanta BarbaraCA93106USA
| | - Kyle A. Emery
- Marine Science InstituteUniversity of CaliforniaSanta BarbaraCA93106USA
| | - Peter A. Hambäck
- Department of Ecology, Environment and Plant SciencesStockholm UniversityStockholmSweden
| | - Christopher J. Henderson
- School of Science, Technology, and EngineeringUniversity of the Sunshine CoastMaroochydoreQueenslandAustralia
| | - David M. Hubbard
- Marine Science InstituteUniversity of CaliforniaSanta BarbaraCA93106USA
| | - Mariano Lastra
- Centro de Investigación Mariña, Edificio CC ExperimentaisUniversidade de Vigo, Campus de Vigo36310VigoSpain
| | - Miguel A. Mateo
- Centre for Marine Ecosystems Research, School of ScienceEdith Cowan UniversityJoondalupWestern AustraliaAustralia,Centro de Estudios Avanzados de Blanes, Consejo Superior de Investigaciones CientíficasBlanesSpain
| | - Andrew Olds
- School of Science, Technology, and EngineeringUniversity of the Sunshine CoastMaroochydoreQueenslandAustralia
| | - Thomas A. Schlacher
- School of Science, Technology, and EngineeringUniversity of the Sunshine CoastMaroochydoreQueenslandAustralia
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8
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Starko S, Neufeld CJ, Gendall L, Timmer B, Campbell L, Yakimishyn J, Druehl L, Baum JK. Microclimate predicts kelp forest extinction in the face of direct and indirect marine heatwave effects. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2673. [PMID: 35584048 DOI: 10.1002/eap.2673] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/22/2022] [Accepted: 03/29/2022] [Indexed: 06/15/2023]
Abstract
Marine heatwaves threaten the persistence of kelp forests globally. However, the observed responses of kelp forests to these events have been highly variable on local scales. Here, we synthesize distribution data from an environmentally diverse region to examine spatial patterns of canopy kelp persistence through an unprecedented marine heatwave. We show that, although often overlooked, temperature variation occurring at fine spatial scales (i.e., a few kilometers or less) can be a critical driver of kelp forest persistence during these events. Specifically, though kelp forests nearly all persisted toward the cool outer coast, inshore areas were >3°C warmer at the surface and experienced extensive kelp loss. Although temperatures remained cool at depths below the thermocline, kelp persistence in these thermal refugia was strongly constrained by biotic interactions, specifically urchin populations that increased during the heatwave and drove transitions to urchin barrens in deeper rocky habitat. Urchins were, however, largely absent from mixed sand and cobble benthos, leading to an unexpected association between bottom substrate and kelp forest persistence at inshore sites with warm surface waters. Our findings demonstrate both that warm microclimates increase the risk of habitat loss during marine heatwaves and that biotic interactions modified by these events will modulate the capacity of cool microclimates to serve as thermal refugia.
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Affiliation(s)
- Samuel Starko
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
| | - Christopher J Neufeld
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
- Department of Biology, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Lianna Gendall
- Department of Geography, University of Victoria, Victoria, British Columbia, Canada
| | - Brian Timmer
- Department of Geography, University of Victoria, Victoria, British Columbia, Canada
| | - Lily Campbell
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
| | - Jennifer Yakimishyn
- Pacific Rim National Park Reserve of Canada, Ucluelet, British Columbia, Canada
| | - Louis Druehl
- Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada
- Canadian Kelp Resources, Bamfield, British Columbia, Canada
| | - Julia K Baum
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
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9
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Comparing the Use of Red-Edge and Near-Infrared Wavelength Ranges for Detecting Submerged Kelp Canopy. REMOTE SENSING 2022. [DOI: 10.3390/rs14092241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Kelp forests are commonly classified within remote sensing imagery by contrasting the high reflectance in the near-infrared spectral region of kelp canopy floating at the surface with the low reflectance in the same spectral region of water. However, kelp canopy is often submerged below the surface of the water, making it important to understand the effects of kelp submersion on the above-water reflectance of kelp, and the depth to which kelp can be detected, in order to reduce uncertainties around the kelp canopy area when mapping kelp. Here, we characterized changes to the above-water spectra of Nereocystis luetkeana (Bull kelp) as different canopy structures (bulb and blades) were submerged in water from the surface to 100 cm in 10 cm increments, while collecting above-water hyperspectral measurements with a spectroradiometer (325–1075 nm). The hyperspectral data were simulated into the multispectral bandwidths of the WorldView-3 satellite and the Micasense RedEdge-MX unoccupied aerial vehicle sensors and vegetation indices were calculated to compare detection limits of kelp with a focus on differences between red edge and near infrared indices. For kelp on the surface, near-infrared reflectance was higher than red-edge reflectance. Once submerged, the kelp spectra showed two narrow reflectance peaks in the red-edge and near-infrared wavelength ranges, and the red-edge peak was consistently higher than the near-infrared peak. As a result, kelp was detected deeper with vegetation indices calculated with a red-edge band versus those calculated with a near infrared band. Our results show that using red-edge bands increased detection of submerged kelp canopy, which may be beneficial for estimating kelp surface-canopy area and biomass.
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10
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García-Reyes M, Thompson SA, Rogers-Bennett L, Sydeman WJ. Winter oceanographic conditions predict summer bull kelp canopy cover in northern California. PLoS One 2022; 17:e0267737. [PMID: 35511813 PMCID: PMC9070938 DOI: 10.1371/journal.pone.0267737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 04/13/2022] [Indexed: 11/18/2022] Open
Abstract
Bull kelp, Nereocystis luetkeana, is an iconic kelp forest species of the Northeast Pacific that provides a wide range of ecosystem services to coastal marine species and society. In northern California, U.S.A., Nereocystis abundance declined sharply in 2014 and has yet to recover. While abiotic and biotic stressors were present prior to 2014, the population collapse highlights the need for a better understanding of how environmental conditions impact Nereocystis. In this study, we used a newly-developed, satellite-based dataset of bull kelp abundance, proxied by canopy cover over 20 years, to test the hypothesis that winter oceanographic conditions determine summer Nereocystis canopy cover. For the years before the collapse (1991 through 2013), wintertime ocean conditions, synthesized in a Multivariate Ocean Climate Indicator (MOCI), were indeed a good predictor of summer Nereocystis canopy cover (R2 = 0.40 to 0.87). We attribute this relationship to the effects of upwelling and/or temperature on nutrient availability. South of Point Arena, California, winter ocean conditions had slightly lower explanatory power than north of Point Arena, also reflective of spring upwelling-driven nutrient entrainment. Results suggest that the Nereocystis gametophytes and/or early sporophytes are sensitive to winter oceanographic conditions. Furthermore, environmental conditions in winter 2014 could have been used to predict the Nereocystis collapse in summer 2014, and for kelp north of Point Arena, a further decline in 2015. Importantly, environmental models do not predict changes in kelp after 2015, suggesting biotic factors suppressed kelp recovery, most likely extreme sea urchin herbivory. Conditions during winter, a season that is often overlooked in studies of biophysical interactions, are useful for predicting summer Nereocystis kelp forest canopy cover, and will be useful in supporting kelp restoration actions in California and perhaps elsewhere in the world.
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Affiliation(s)
| | | | - Laura Rogers-Bennett
- Coastal Marine Science Institute, Karen C. Drayer, Wildlife Health Center, UC Davis, Bodega Marine Lab, Bodega Bay, California, United States of America
- California Department Fish and Wildlife, Bodega Marine Lab, Bodega Bay, California, United States of America
| | - William J. Sydeman
- Farallon Institute, Petaluma, California, United States of America
- Bodega Marine Lab, UC Davis, Bodega Bay, California, United States of America
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Houskeeper HF, Rosenthal IS, Cavanaugh KC, Pawlak C, Trouille L, Byrnes JEK, Bell TW, Cavanaugh KC. Automated satellite remote sensing of giant kelp at the Falkland Islands (Islas Malvinas). PLoS One 2022; 17:e0257933. [PMID: 34990455 PMCID: PMC8735600 DOI: 10.1371/journal.pone.0257933] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 12/20/2021] [Indexed: 11/30/2022] Open
Abstract
Giant kelp populations that support productive and diverse coastal ecosystems at temperate and subpolar latitudes of both hemispheres are vulnerable to changing climate conditions as well as direct human impacts. Observations of giant kelp forests are spatially and temporally uneven, with disproportionate coverage in the northern hemisphere, despite the size and comparable density of southern hemisphere kelp forests. Satellite imagery enables the mapping of existing and historical giant kelp populations in understudied regions, but automating the detection of giant kelp using satellite imagery requires approaches that are robust to the optical complexity of the shallow, nearshore environment. We present and compare two approaches for automating the detection of giant kelp in satellite datasets: one based on crowd sourcing of satellite imagery classifications and another based on a decision tree paired with a spectral unmixing algorithm (automated using Google Earth Engine). Both approaches are applied to satellite imagery (Landsat) of the Falkland Islands or Islas Malvinas (FLK), an archipelago in the southern Atlantic Ocean that supports expansive giant kelp ecosystems. The performance of each method is evaluated by comparing the automated classifications with a subset of expert-annotated imagery (8 images spanning the majority of our continuous timeseries, cumulatively covering over 2,700 km of coastline, and including all relevant sensors). Using the remote sensing approaches evaluated herein, we present the first continuous timeseries of giant kelp observations in the FLK region using Landsat imagery spanning over three decades. We do not detect evidence of long-term change in the FLK region, although we observe a recent decline in total canopy area from 2017-2021. Using a nitrate model based on nearby ocean state measurements obtained from ships and incorporating satellite sea surface temperature products, we find that the area of giant kelp forests in the FLK region is positively correlated with the nitrate content observed during the prior year. Our results indicate that giant kelp classifications using citizen science are approximately consistent with classifications based on a state-of-the-art automated spectral approach. Despite differences in accuracy and sensitivity, both approaches find high interannual variability that impedes the detection of potential long-term changes in giant kelp canopy area, although recent canopy area declines are notable and should continue to be monitored carefully.
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Affiliation(s)
- Henry F. Houskeeper
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
| | - Isaac S. Rosenthal
- School for the Environment, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Katherine C. Cavanaugh
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
| | - Camille Pawlak
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
| | - Laura Trouille
- The Adler Planetarium, Chicago, Illinois, United States of America
| | - Jarrett E. K. Byrnes
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Tom W. Bell
- Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | - Kyle C. Cavanaugh
- Department of Geography, University of California Los Angeles, Los Angeles, California, United States of America
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Nosal AP, Cartamil DP, Ammann AJ, Bellquist LF, Ben‐Aderet NJ, Blincow KM, Burns ES, Chapman ED, Freedman RM, Klimley AP, Logan RK, Lowe CG, Semmens BX, White CF, Hastings PA. Triennial migration and philopatry in the critically endangered soupfin shark
Galeorhinus galeus. J Appl Ecol 2021. [DOI: 10.1111/1365-2664.13848] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrew P. Nosal
- Department of Environmental and Ocean Sciences University of San Diego San Diego CA USA
- Marine Biology Research Division Scripps Institution of Oceanography University of California – San Diego La Jolla CA USA
| | - Daniel P. Cartamil
- Marine Biology Research Division Scripps Institution of Oceanography University of California – San Diego La Jolla CA USA
| | - Arnold J. Ammann
- Fisheries Ecology Division Southwest Fisheries Science Center National Marine Fisheries ServiceNOAA Santa Cruz CA USA
| | - Lyall F. Bellquist
- Marine Biology Research Division Scripps Institution of Oceanography University of California – San Diego La Jolla CA USA
- The Nature Conservancy San Francisco CA USA
| | - Noah J. Ben‐Aderet
- Fisheries Resources Division Southwest Fisheries Science Center NOAA Fisheries La Jolla CA USA
| | - Kayla M. Blincow
- Marine Biology Research Division Scripps Institution of Oceanography University of California – San Diego La Jolla CA USA
| | - Echelle S. Burns
- Bren School of Environmental Science and Management University of California – Santa Barbara Santa Barbara CA USA
| | - Eric D. Chapman
- Department of Wildlife, Fish and Conservation Biology University of California – Davis Davis CA USA
- ICF Sacramento CA USA
| | - Ryan M. Freedman
- NOAA Channel Islands National Marine Sanctuary University of California – Santa Barbara Santa Barbara CA USA
| | - A. Peter Klimley
- Department of Wildlife, Fish and Conservation Biology University of California – Davis Davis CA USA
- Biotelemetry Consultants Petaluma CA USA
| | - Ryan K. Logan
- Guy Harvey Research Institute Nova Southeastern University Dania Beach FL USA
| | | | - Brice X. Semmens
- Marine Biology Research Division Scripps Institution of Oceanography University of California – San Diego La Jolla CA USA
| | - Connor F. White
- Department of Organismic and Evolutionary Biology Harvard University Cambridge MA USA
| | - Philip A. Hastings
- Marine Biology Research Division Scripps Institution of Oceanography University of California – San Diego La Jolla CA USA
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Berry HD, Mumford TF, Christiaen B, Dowty P, Calloway M, Ferrier L, Grossman EE, VanArendonk NR. Long-term changes in kelp forests in an inner basin of the Salish Sea. PLoS One 2021; 16:e0229703. [PMID: 33596204 PMCID: PMC7888675 DOI: 10.1371/journal.pone.0229703] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 01/18/2021] [Indexed: 11/30/2022] Open
Abstract
Kelp forests form an important biogenic habitat that responds to natural and human drivers. Global concerns exist about threats to kelp forests, yet long-term information is limited and research suggests that trends are geographically distinct. We examined distribution of the bull kelp Nereocystis luetkeana over 145 years in South Puget Sound (SPS), a semi-protected inner basin in a fjord estuary complex in the northeast Pacific Ocean. We synthesized 48 historical and modern Nereocystis surveys and examined presence/absence within 1-km segments along 452 km of shoreline. Compared to the earliest baseline in 1878, Nereocystis extent in 2017 decreased 63%, with individual sub-basins showing up to 96% loss. Losses have persisted for decades, across a range of climate conditions. In recent decades, Nereocystis predominantly occurred along shorelines with intense currents and mixing, where temperature and nutrient concentrations did not reach thresholds for impacts to Nereocystis performance, and high current speeds likely excluded grazers. Losses predominated in areas with elevated temperature, lower nutrient concentrations, and relatively low current velocities. The pattern of long-term losses in SPS contrasts with stability in floating kelp abundance during the last century in an area of the Salish Sea with greater wave exposure and proximity to oceanic conditions. These findings support the hypothesis that kelp beds along wave-sheltered shorelines exhibit greater sensitivity to environmental stressors. Additionally, shorelines with strong currents and deep-water mixing may provide refugia within sheltered systems.
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Affiliation(s)
- Helen D. Berry
- Washington State Department of Natural Resources, Olympia, WA, United States of America
| | | | - Bart Christiaen
- Washington State Department of Natural Resources, Olympia, WA, United States of America
| | - Pete Dowty
- Washington State Department of Natural Resources, Olympia, WA, United States of America
| | - Max Calloway
- Washington State Department of Natural Resources, Olympia, WA, United States of America
| | - Lisa Ferrier
- Washington State Department of Natural Resources, Olympia, WA, United States of America
| | - Eric E. Grossman
- U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA, United States of America
| | - Nathan R. VanArendonk
- U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA, United States of America
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