Diatom Biogeography From the Labrador Sea Revealed Through a Trait-Based Approach

Glaucia M Fragoso,Erica J H Head,Alex J Poulton,Geir Johnsen,Duncan A Purdie,Igor M Yashayaev

doi:10.3389/fmars.2018.00297

Abstract

Diatoms are a keystone algal group, with diverse cell morphology and a global distribution. The biogeography of morphological, functional and life-history traits of marine diatoms were investigated in Arctic and Atlantic waters of the Labrador Sea during the spring bloom (2013-2014). In this study, trait-based analysis using community-weighted means showed that low temperatures (<0oC) in Arctic waters correlated positively with diatom species that have traits such as low temperature optimum growth and the ability to produced ice-binding proteins, highlighting their sea-ice origin. High silicate concentrations in Arctic waters, as well as sea-ice cover and shallow bathymetry, favoured diatom species that were heavily silicified, colonial and capable of producing resting spores, suggesting that these are important traits for this community. In Atlantic waters, diatom species with large surface area to volume ratios were dominant in deep mixed layers, whilst low silicate to nitrate ratios correlated positively with weakly silicified species. Sharp cell projections, such as processes or spines, were positively correlated with water-column stratification, indicating that these traits promote positive buoyancy for diatom cells. Our trait-based analysis directly links cell morphology and physiology with diatom species distribution, highlighting allowing new insights on how this method can potentially be applied to explain ecophysiology and shifting biogeographical distributions in a warming climate.

Highlights

Diatoms are one of the most ubiquitous and functionally diverse unicellular eukaryotic groups on the planet, contributing to around 20% of global primary productivity and 40% of oceanic primary production (Malviya et al, 2016)
Stations in this study were classified as Arctic or Atlanticinfluenced based on vertical distributions of potential temperature (T), salinity (S), and density
The stations dominated by Atlantic-related waters found in the central part of the Labrador Sea had a weaker pycnocline and were warmer and saltier (Figures 3a–c)

Summary

Introduction

Diatoms are one of the most ubiquitous and functionally diverse unicellular eukaryotic groups on the planet, contributing to around 20% of global primary productivity and 40% of oceanic primary production (Malviya et al, 2016). Marine diatom abundance, species composition, and genus diversity exhibit biogeographical patterns in their spatial distributions (Rytter Hasle, 1976; Malviya et al, 2016; Tréguer et al, 2018). One way to refine functional variability is by using trait-based approaches, which define species in terms of their ecological roles that capture key aspects of organismal functionality in the system (Litchman et al, 2007; Litchman and Klausmeier, 2008; Glibert, 2016). Instead of using simple taxonomic ecology to explain species distribution, biogeography, seasonality and/or long-term trends, functional traits analysis has the potential to give a realistic prediction of a biological community’s response to changes in the environment (McGill et al, 2006)

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Results

Conclusion