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On the Seasonal Dynamics of Phytoplankton Chlorophyll-a Concentration in Nearshore and Offshore Waters of Plymouth, in the English Channel: Enlisting the Help of a Surfer

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Centre for Geography and Environmental Science, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, Cornwall, UK
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Plymouth Marine Laboratory, Plymouth PL1 3DH, Devon, UK
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Royal Belgian Institute of Natural Sciences, Operational Directorate Natural Environments, Vautierstraat 29, 1000 Brussels, Belgium
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Department of Earth and Ocean Sciences, University of North Carolina Wilmington, Wilmington, NC 28403-5944, USA
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Department of Marine and Environmental Sciences, Nova Southeastern University, Dania Beach, FL 33004, USA
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Scripps Institution of Oceanography, University of California, San Diego, CA 92037, USA
*
Author to whom correspondence should be addressed.
Academic Editors: Giovanni Scicchitano and Diego Macías
Oceans 2022, 3(2), 125-146; https://doi.org/10.3390/oceans3020011
Received: 20 January 2022 / Revised: 19 February 2022 / Accepted: 17 March 2022 / Published: 1 April 2022
(This article belongs to the Special Issue Land-Ocean Interactions)
The role of phytoplankton as ocean primary producers and their influence on global biogeochemical cycles makes them arguably the most important living organisms in the sea. Like plants on land, phytoplankton exhibit seasonal cycles that are controlled by physical, chemical, and biological processes. Nearshore coastal waters often contain the highest levels of phytoplankton biomass. Yet, owing to difficulties in sampling this dynamic region, less is known about the seasonality of phytoplankton in the nearshore (e.g., surf zone) compared to offshore coastal, shelf and open ocean waters. Here, we analyse an annual dataset of chlorophyll-a concentration—a proxy of phytoplankton biomass—and sea surface temperature (SST) collected by a surfer at Bovisand Beach in Plymouth, UK on a near weekly basis between September 2017 and September 2018. By comparing this dataset with a complementary in-situ dataset collected 7 km offshore from the coastline (11 km from Bovisand Beach) at Station L4 of the Western Channel Observatory, and guided by satellite observations of light availability, we investigated differences in phytoplankton seasonal cycles between nearshore and offshore coastal waters. Whereas similarities in phytoplankton biomass were observed in autumn, winter and spring, we observed significant differences between sites during the summer months of July and August. Offshore (Station L4) chlorophyll-a concentrations dropped dramatically, whereas chlorophyll-a concentrations in the nearshore (Bovsiand Beach) remained high. We found chlorophyll-a in the nearshore to be significantly positively correlated with SST and PAR over the seasonal cycle, but no significant correlations were observed at the offshore location. However, offshore correlation coefficients were found to be more consistent with those observed in the nearshore when summer data (June–August 2018) were removed. Analysis of physical (temperature and density) and chemical variables (nutrients) suggest that the offshore site (Station L4) becomes stratified and nutrient limited at the surface during the summer, in contrast to the nearshore. However, we acknowledge that additional experiments are needed to verify this hypothesis. Considering predicted changes in ocean stratification, our findings may help understand how the spatial distribution of phytoplankton phenology within temperate coastal seas could be impacted by climate change. Additionally, this study emphasises the potential for using marine citizen science as a platform for acquiring environmental data in otherwise challenging regions of the ocean, for understanding ecological indicators such as phytoplankton abundance and phenology. We discuss the limitations of our study and future work needed to explore nearshore phytoplankton dynamics. View Full-Text
Keywords: phytoplankton; chlorophyll-a; phenology; citizen science; coastal; nearshore; surfers phytoplankton; chlorophyll-a; phenology; citizen science; coastal; nearshore; surfers
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MDPI and ACS Style

McCluskey, E.; Brewin, R.J.W.; Vanhellemont, Q.; Jones, O.; Cummings, D.; Tilstone, G.; Jackson, T.; Widdicombe, C.; Woodward, E.M.S.; Harris, C.; Bresnahan, P.J.; Cyronak, T.; Andersson, A.J. On the Seasonal Dynamics of Phytoplankton Chlorophyll-a Concentration in Nearshore and Offshore Waters of Plymouth, in the English Channel: Enlisting the Help of a Surfer. Oceans 2022, 3, 125-146. https://doi.org/10.3390/oceans3020011

AMA Style

McCluskey E, Brewin RJW, Vanhellemont Q, Jones O, Cummings D, Tilstone G, Jackson T, Widdicombe C, Woodward EMS, Harris C, Bresnahan PJ, Cyronak T, Andersson AJ. On the Seasonal Dynamics of Phytoplankton Chlorophyll-a Concentration in Nearshore and Offshore Waters of Plymouth, in the English Channel: Enlisting the Help of a Surfer. Oceans. 2022; 3(2):125-146. https://doi.org/10.3390/oceans3020011

Chicago/Turabian Style

McCluskey, Elliot, Robert J.W. Brewin, Quinten Vanhellemont, Oban Jones, Denise Cummings, Gavin Tilstone, Thomas Jackson, Claire Widdicombe, E. M.S. Woodward, Carolyn Harris, Philip J. Bresnahan, Tyler Cyronak, and Andreas J. Andersson. 2022. "On the Seasonal Dynamics of Phytoplankton Chlorophyll-a Concentration in Nearshore and Offshore Waters of Plymouth, in the English Channel: Enlisting the Help of a Surfer" Oceans 3, no. 2: 125-146. https://doi.org/10.3390/oceans3020011

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