Insights into the life strategy of the common marine diatom Chaetoceros peruvianus Brightwell.

Mirta Smodlaka Tanković,Ingrid Ivančić,Martin Pfannkuchen,Emina Pustijanac,Nikola Medić,Daniela Marić Pfannkuchen,Ana Baričević,Nataša Kužat,Tihana Novak,Blaženka Gašparović,Adrianna Ianora

doi:10.1371/journal.pone.0203634

Mirta Smodlaka Tanković, Ingrid Ivančić + Show 9 more

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https://doi.org/10.1371/journal.pone.0203634

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Abstract

Chaetoceros peruvianus is a marine diatom species with circumglobal distribution. While frequently observed, it appears never to dominate the marine phytoplankton community hence it can be characterized as a rather opportunistic, generalistic species. Here we present ecological interpretations from a long-term data set on marine microphytoplankton in the northern Adriatic Sea, where the abundancies and relative contributions of C. peruvianus were observed along a set of steep ecological gradients. Limited supply of dissolved inorganic phosphate was identified as the driving ecological factor for this ecosystem. In parallel C. peruvianus was cultivated in monoclonal cultures and its morphological and physiological reaction to replete and phosphorus depleted medium was analysed. C. peruvianus reacted to phosphorus depletion by an increase in cell height and length as well as thickness and length of setae. This morphological reaction included an increase in cellular volume and calculated carbon content. Additionally, it represents the transition between two described morphological varieties, C. peruvianus and C. peruvianus var. robusta. C. peruvianus showed a significant induction of extracellular alkaline phosphatase activity if grown in phosphate depleted medium. Microscopical analysis demonstrated this activity to be located exclusively on the setae of the cells.

Highlights

The diatom genus Chaetoceros Ehrenberg is one of the largest and most diverse diatom genera [1,2]
Nucleotide BLAST similarity search found only one ribulose bisphosphate carboxylase large subunit (rbcL) sequence identified as C. peruvianus in the GenBank database [57]
On 4 stations across the northern Adriatic we found a stable pattern of alkaline phosphatase activity (APA) in seawater that rose in spring during the onset of stratification and fell in late autumn during the onset of water column mixing (Fig 8)

Summary

Introduction

The diatom genus Chaetoceros Ehrenberg is one of the largest and most diverse diatom genera [1,2]. It contains more than 200 currently accepted species and more than 100 intraspecific names [2,3]. More than 300 taxa were described so far [1,3]. Characteristic morphological features of these centric diatoms are their setae, hollow spine-like structures, that protrude from the valve face or margin. Most species of the genus Chaetoceros form chains by either fusion of setae or direct attachments between valves.

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