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

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.

First regional reference database of northern Adriatic diatom transcriptomes

“…The input from the Po River creates steep spatio-temporal ecological gradients in the northern Adriatic 17 , 18 , 46 , 47 which together with the current circulation creates dynamic ecological conditions for the growth and succession of phytoplankton. In the NA, phytoplankton life strategies are mainly determined by light availability, temperature and the species' ability to cope with phosphorus limitation 17 – 19 , 48 – 51 . As the Po River is characterized by a much higher concentration of nitrogen, compared to phosphorus 52 the species living and thriving in the northern Adriatic are used to unbalanced N/P ratio.…”

Whole-genome scanning reveals selection mechanisms in epipelagic Chaetoceros diatom populations

“…C. debilis, of which our MAG SOC_60 was also found to be very close, was retrieved in different localities: in European coastal waters and in the Arctic Ocean for the northern hemisphere, as well as in the Indian and Southern Oceans, in agreement with the distribution of this MAG. Chaetoceros has been viewed as a local opportunistic genus (Barton et al 2010;Smodlaka Tanković et al 2018) but the various species we describe here appeared to evolve in sympatry with up to three MAG populations in the same sampling stations. A temporal survey of these sampling points could help reveal whether the populations from different species are sympatric on a regular manner or if some competition mechanisms or niche exclusions are observable.…”

Whole-genome scanning reveals environmental selection mechanisms that shape diversity in populations of the epipelagic diatom Chaetoceros

“…debilis , of which our MAG SOC_60 was also found to be relatively close, was retrieved in different localities: in European coastal waters and in the Arctic Ocean for the northern hemisphere, as well as in the Indian and Southern Oceans, in agreement with the distribution of the MAG. Chaetoceros has been viewed as a local opportunistic genus [ 89 , 90 ] but the various species we describe here appeared to evolve in sympatry with up to 3 MAG populations in the same sampling stations. A temporal survey of these sampling points could help reveal whether the populations from different species are sympatric on a regular manner or if some competition mechanisms or niche exclusions are observable.…”