Spatial and long-term changes in the functional and structural phytoplankton communities along the French Atlantic coast

David, Valérie; Ryckaert, Mireille; Karpytchev, Mikhaïl; Bacher, Cédric; Arnaudeau, Vanessa; Vidal, Nadia; Maurer, Danièle; Niquil, Nathalie

doi:10.1016/j.ecss.2012.02.017

Cited by 28 publications

(23 citation statements)

References 78 publications

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“…A 'full model' including both types of drivers was also compared to the aforementioned more parcimonious models. Climate indices (NAO and AMO) were included in a monthly model but explained little of the observed variation, in line with previous results for AB (David et al 2012). As they were also more difficult to interpret ecologically, they were discarded from further analyses.…”

Section: Environmental Drivers Of Population Dynamicssupporting

confidence: 60%

Coastal phytoplankton community dynamics and coexistence driven by intragroup density‐dependence, light and hydrodynamics

Barraquand

Picoche

Maurer

et al. 2018

Oikos

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Phytoplanktonic communities maintain a high diversity in a seemingly homogeneous environment, competing for the same set of resources. Many theories have been proposed to explain this coexistence despite likely competition, such as contrasted responses to temporal environmental variation. However, theory has developed at a faster pace than empirical evaluation using field data, which requires inferring drivers of community dynamics from observational time series. Here, we combine autoregressive models with a data set spanning more than 20 years of phytoplankton counts every two weeks, together with nutrients and physical variables. By comparing models dominated by nutrients or physical variables (hydrodynamics and climate), we first explore which abiotic factors contribute more to phytoplankton growth and decline. We find that physical drivers – such as irradiance, wind, and salinity – explain some of the variability in abundances unexplained by biotic interactions. In contrast, responses to nutrients explain less of the phytoplankton variability. Concerning biotic drivers of community dynamics, multivariate autoregressive models reveal that competition between different groups (genera) has a much weaker effect on population growth rates than competition within a group. In fact, the few biotic interactions between genera that are detected are frequently positive. Hence, our system is unlikely to be best represented as a set of competitors whose differing responses to fluctuating environments allow coexistence, as in ‘paradox of the plankton’ models with a storage effect or a relative nonlinearity of competition. Coexistence is more likely to result from high intragroup density‐dependence. Competition between phytoplanktonic groups and nutrient limitation are often invoked as drivers of phytoplankton dynamics; our findings suggest instead that more attention should be given to the physical structure of the environment and natural enemies such as grazers and pathogens, that could explain the high intraspecific density dependence found here.

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Section: Environmental Drivers Of Population Dynamicssupporting

confidence: 60%

Coastal phytoplankton community dynamics and coexistence driven by intragroup density‐dependence, light and hydrodynamics

Barraquand

Picoche

Maurer

et al. 2018

Oikos

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show abstract

“…Climate indices (NAO and AMO) formed a third group of variables for which we developed a monthly model. Coefficients associated to climate indices were low and explained little the observed variation, which was in line with previous results for AB (David et al 2012); we therefore chose to discard such large-scale indices from further analyses, as they were also more difficult to interpret ecologically.…”

Section: Environmental Drivers Of Population Dynamicssupporting

confidence: 83%

“…A switch from early, large plankton assemblage with low biodiversity to a more diverse and smaller-bodied community has been noticed by Glé et al (2008) although the latter study was restricted to a single year (2003), characterized by a dry winter and a strong summer heat wave. AB is also characterized by a higher average salinity and lower turbidity than other French Atlantic coastal bays where biotic and abiotic factors are similarly monitored (David et al 2012).…”

Section: Plankton Ecology In Arcachon Baymentioning

confidence: 99%

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Weak interactions between groups and physical drivers of community dynamics in coastal phytoplankton

Barraquand

Picoche

Maurer

et al. 2017

Preprint

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Phytoplanktonic communities maintain a high diversity in a seemingly homogeneous environment, competing for the same set of resources. Many theories have been proposed to explain this coexistence despite likely competition, such as contrasted responses to temporal environmental variation. However, theory has developed at a faster pace than its empirical evaluation using field data, that requires to infer biotic and abiotic drivers of community dynamics from observational time series. Here, we combine autoregressive models with a data set spanning more than 20 years of biweekly plankton counts and abiotic variables, including nutrients and physical variables. By comparing models dominated by nutrients or physical variables (hydrodynamics and climate), we first explore which abiotic factors contribute more to phytoplankton growth and decline. We find that physical drivers -such as irradiance, wind, and salinity -explain some of the variability in abundances unexplained by biotic interactions. In contrast, responses to nutrients explain less of phytoplankton variability. Concerning biotic drivers of community dynamics, multivariate autoregressive models reveal that competition between different groups (at the genus level for most) has a much weaker effect on population growth rates than competition within a group. In fact, the few biotic interactions between genera that are detected are frequently positive. Hence, our system is unlikely to be best represented as a set of competitors whose differing responses to fluctuating environments allow coexistence, as in "paradox of the plankton" models with a storage effect or a relative nonlinearity of competition. Coexistence is more likely to result from stabilizing niche differences, manifested through high intragroup density-dependence. Competition between planktonic groups and nutrients are often invoked as drivers of phytoplankton dynamics; our findings suggest instead that more attention should be given to the physical structure of the environment and natural enemies, for coastal phytoplankton at least.

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“…The tidal range varies from 2.5 to 5 m (Vested et al, 2013). In this zone, freshwater influence is also provided by the Loire river (mean annual flow 931 m 3 s À1 ) (David et al, 2012). Diatoms belonging to the genera Leptocylindrus, Skeletonema and Chaetoceros dominate the microphytoplankton community (Ifremer, Laboratoire Environnement Ressources Morbihan Pays de Loire, 2013).…”

Section: Study Areamentioning

confidence: 99%

Assessing phytoplankton realized niches using a French national phytoplankton monitoring network

Fariñas

Bacher

Soudant

et al. 2015

Estuarine, Coastal and Shelf Science

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Keywords: phytoplankton environment niche position tolerance kernel density outlying mean index a b s t r a c t Relating environmental factors to species occurrence is a fundamental step in a better understanding of the community structure, the spatial and temporal dynamics of populations and how species may respond to environmental changes. In this paper, we used phytoplankton occurrence data, from a French national phytoplankton monitoring network, and environmental variables with the aim of characterizing the realized ecological niches of phytoplankton groups. We selected 35 phytoplankton taxa representing the most important taxa in terms of occurrence frequency and abundance along the French coast of the eastern English Channel, the Southern Bight of the North Sea and the Atlantic Ocean. We show that environmental variables such as nutrient concentration, water temperature, irradiance and turbidity can be considered key factors controlling phytoplankton dynamics and influencing the community structure. By using a statistical framework based on an ordination technique the community structure was analyzed and interpreted in terms of niche overlap, marginality and tolerance. The most marginal taxon was Dactyliosolen and the most tolerant was Skeletonema. Non-marginal taxonomic units could be generalist and specialist, while marginal taxa were rather specialist. Specialist and marginal taxa globally showed lower values of overlap.

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Spatial and long-term changes in the functional and structural phytoplankton communities along the French Atlantic coast

Cited by 28 publications

References 78 publications

Coastal phytoplankton community dynamics and coexistence driven by intragroup density‐dependence, light and hydrodynamics

Coastal phytoplankton community dynamics and coexistence driven by intragroup density‐dependence, light and hydrodynamics

Weak interactions between groups and physical drivers of community dynamics in coastal phytoplankton

Assessing phytoplankton realized niches using a French national phytoplankton monitoring network

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