Phytoplankton communities in Eastern Mediterranean coastal waters
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PROVIDER: PRJEB40572 | ENA |
REPOSITORIES: ENA
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Project description:This study considers variability in phytoplankton and heterotrophic bacterial abundances and production rates, in one of the most oligotrophic marine regions in the world-the Levantine Basin. The temporal dynamics of these planktonic groups were studied in the coastal waters of the southeastern Mediterranean Sea approximately every two weeks for a total of two years. Heterotrophic bacteria were abundant mostly during late summer and midwinter, and were positively correlated with bacterial production and with N2 fixation. Based on size fractionating, picophytoplankton was abundant during the summer, whereas nano-microphytoplankton predominated during the winter and early spring, which were also evident in the size-fractionated primary production rates. Autotrophic abundance and production correlated negatively with temperature, but did not correlate with inorganic nutrients. Furthermore, a comparison of our results with results from the open Levantine Basin demonstrates that autotrophic and heterotrophic production, as well as N2 fixation rates, are considerably higher in the coastal habitat than in the open sea, while nutrient levels or cell abundance are not different. These findings have important ecological implications for food web dynamics and for biological carbon sequestration in this understudied region.
| S-EPMC4608699 | biostudies-literature
Project description:Phytoplankton blooms are an important, widespread phenomenon in open oceans, coastal waters and freshwaters, supporting food webs and essential ecosystem services. Blooms are even more important in exploited coastal waters for maintaining high resource production. However, the environmental factors driving blooms in shallow productive coastal waters are still unclear, making it difficult to assess how environmental fluctuations influence bloom phenology and productivity. To gain insights into bloom phenology, Chl a fluorescence and meteorological and hydrological parameters were monitored at high-frequency (15 min) and nutrient concentrations and phytoplankton abundance and diversity, were monitored weekly in a typical Mediterranean shallow coastal system (Thau Lagoon). This study was carried out from winter to late spring in two successive years with different climatic conditions: 2014/2015 was typical, but the winter of 2015/2016 was the warmest on record. Rising water temperature was the main driver of phytoplankton blooms. However, blooms were sometimes correlated with winds and sometimes correlated with salinity, suggesting nutrients were supplied by water transport via winds, saltier seawater intake, rain and water flow events. This finding indicates the joint role of these factors in determining the success of phytoplankton blooms. Furthermore, interannual variability showed that winter water temperature was higher in 2016 than in 2015, resulting in lower phytoplankton biomass accumulation in the following spring. Moreover, the phytoplankton abundances and diversity also changed: cyanobacteria (< 1 μm), picoeukaryotes (< 1 μm) and nanoeukaryotes (3-6 μm) increased to the detriment of larger phytoplankton such as diatoms. Water temperature is a key factor affecting phytoplankton bloom dynamics in shallow productive coastal waters and could become crucial with future global warming by modifying bloom phenology and changing phytoplankton community structure, in turn affecting the entire food web and ecosystem services.
| S-EPMC6450617 | biostudies-literature
Project description:Characterization and Biotechnological Potential of Hydrocarbon-Degrading Consortia from Surface and Deep Waters of the Eastern Mediterranean Sea.
| PRJEB43541 | ENA
Project description:Year-round reports of phytoplankton dynamics in the West Antarctic Peninsula are rare and mainly limited to microscopy and/or pigment-based studies. We analyzed the phytoplankton community from coastal waters of Fildes Bay in the West Antarctic Peninsula between January 2014 and 2015 using metabarcoding of the nuclear and plastidial 18/16S rRNA gene from both size-fractionated and flow cytometry sorted samples. Overall 14 classes of photosynthetic eukaryotes were present in our samples with the following dominating: Bacillariophyta (diatoms), Pelagophyceae and Dictyochophyceae for division Ochrophyta, Mamiellophyceae and Pyramimonadophyceae for division Chlorophyta, Haptophyta and Cryptophyta. Each metabarcoding approach yielded a different image of the phytoplankton community with for example Prymnesiophyceae more prevalent in plastidial metabarcodes and Mamiellophyceae in nuclear ones. Diatoms were dominant in the larger size fractions and during summer, while Prymnesiophyceae and Cryptophyceae were dominant in colder seasons. Pelagophyceae were particularly abundant towards the end of autumn (May). In addition of Micromonas polaris and Micromonas sp. clade B3, both previously reported in Arctic waters, we detected a new Micromonas 18S rRNA sequence signature, close to, but clearly distinct from M. polaris, which potentially represents a new clade specific of the Antarctic. These results highlight the need for complementary strategies as well as the importance of year-round monitoring for a comprehensive description of phytoplankton communities in Antarctic coastal waters.
| S-EPMC7809266 | biostudies-literature
Project description:Sargassum is one of the most diverse brown algal genus with more than 150 known species, mostly benthic and few pelagic species. They contribute significantly to global primary production and serve as important habitat for wide range of marine organisms. Sargassum vulgare is one of the dominant habitat forming species along Mediterranean coast. Despite their huge ecological importance, it is relatively unknown how they will respond under future global climate change scenario. This work used de novo transcriptome sequencing approach to understand the molecular response of S. vulgare to chronic acidification at the shallow underwater volcanic CO2 vents off Ischia Island, Italy. Keywords: brown algae, Sargassum, de novo transcriptome, ocean acidification, CO2 vents.
2017-01-16 | GSE78707 | GEO
Project description:Phytoplankton produce large amounts of polysaccharide gel material known as transparent exopolymer particles (TEP). We investigated the potential links between phytoplankton-derived TEP and microbial community structure in the sea surface microlayer and underlying water at the English Channel time-series station L4 during a spring diatom bloom, and in two adjacent estuaries. Major changes in bacterioneuston and bacterioplankton community structure occurred after the peak of the spring bloom at L4, and coincided with the significant decline of microlayer and water column TEP. Increased abundance of Flavobacteriales and Rhodobacterales in bacterioneuston and bacterioplankton communities at L4 was significantly related to the TEP decline, indicating that both taxa could be responsible. The results suggest that TEP is an important factor in determining microbial diversity in coastal waters, and that TEP utilisation could be a niche occupied by Flavobacteriales and Rhodobacterales.
| S-EPMC3869024 | biostudies-literature
Project description:In terrestrial ecosystems, transitional areas between different plant communities (ecotones) are formed by steep environmental gradients and are commonly characterized by high species diversity and primary productivity, which in turn influences the foodweb structure of these regions. Whether comparable zones of elevated diversity and productivity characterize ecotones in the oceans remains poorly understood. Here we describe a previously hidden hotspot of phytoplankton diversity and productivity in a narrow but seasonally persistent transition zone at the intersection of iron-poor, nitrate-rich offshore waters and iron-rich, nitrate-poor coastal waters of the Northeast Pacific Ocean. Novel continuous measurements of phytoplankton cell abundance and composition identified a complex succession of blooms of five distinct size classes of phytoplankton populations within a 100-km-wide transition zone. The blooms appear to be fueled by natural iron enrichment of offshore communities as they are transported toward the coast. The observed succession of phytoplankton populations is likely driven by spatial gradients in iron availability or time since iron enrichment. Regardless of the underlying mechanism, the resulting communities have a strong impact on the regional biogeochemistry as evidenced by the low partial pressure of CO(2) and the nearly complete depletion of nutrients. Enhanced phytoplankton productivity and diversity associated with steep environmental gradients are expected wherever water masses with complementary nutrient compositions mix to create a region more favorable for phytoplankton growth. The ability to detect and track these important but poorly characterized marine ecotones is critical for understanding their impact on productivity and ecosystem structure in the oceans.
| S-EPMC2944761 | biostudies-literature
Project description:Phytoplankton communities in the shallow eastern Mediterranean coastal waters
| PRJNA670617 | ENA
Project description:Phytoplankton and heterotrophic bacteria rely on a suite of inorganic and organic macronutrients to satisfy their cellular needs. Here, we explored the effect of dissolved inorganic phosphate (PO4) and several dissolved organic molecules containing phosphorus [ATP, glucose-6-phosphate, 2-aminoethylphosphonic acid, collectively referred to as dissolved organic phosphorus (DOP)], on the activity and biomass of autotrophic and heterotrophic microbial populations in the coastal water of the southeastern Mediterranean Sea (SEMS) during summertime. To this end, surface waters were supplemented with PO4, one of the different organic molecules, or PO4 + ATP, and measured the PO4 turnover time (Tt), alkaline phosphatase activity (APA), heterotrophic bacterial production (BP), primary production (PP), and the abundance of the different microbial components. Our results show that PO4 alone does not stimulate any significant change in most of the autotrophic or heterotrophic bacterial variables tested. ATP addition (alone or with PO4) triggers the strongest increase in primary and bacterial productivity or biomass. Heterotrophic bacterial abundance and BP respond faster than phytoplankton (24 h post addition) to the various additions of DOP or PO4 + ATP, followed by a recovery of primary productivity (48 h post addition). These observations suggest that both autotrophic and heterotrophic microbial communities compete for labile organic molecules containing P, such as ATP, to satisfy their cellular needs. It also suggests that SEMS coastal water heterotrophic bacteria are likely C and P co-limited.
| S-EPMC6706821 | biostudies-literature