Planktonic ciliates in the Baltic Sea in summer: distribution, species association and estimated grazing impact

Setälä, Outi; Kivi, Kai

doi:10.3354/ame032287

Cited by 33 publications

(18 citation statements)

References 50 publications

(59 reference statements)

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“…As the sum of OTUs matching to freshwater and marine sequences is relatively constant along the salinity gradient (Figure 4), the a-diversity at intermediate salinities is likely not primarily maintained by phylogenetically divergent brackish water specialists, but rather by adapted bacteria originating from marine and freshwater environments. The observed diversity likely represents actively reproducing populations, as protist grazing implies a fast turnover of picoplankton in surface waters of the Baltic Sea, similar to in other pelagic systems (Setälä and Kivi, 2003). The Baltic Sea was formed after the last glaciation (10 000-15 000 years ago) and is a, in a geological and evolutionary timescale, young sea (Feistel et al, 2008).…”

Section: Resultsmentioning

confidence: 89%

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

et al. 2011

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Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater-freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche.

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Section: Resultsmentioning

confidence: 89%

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

et al. 2011

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“…Some of the highest rates of primary production in the sea have been measured in red waters caused by this ciliate (Crawford 1989 Myrionecta rubra occurs more routinely at low densities and can be found year-round in most estuarine and coastal waters (Crawford 1989, Montagnes & Lynn 1989, Smith & Hansen 2007. It is often an important member of the microplankton in winter, in turbid waters, and at or near the base of the euphotic zone, all of which are relatively low light environments (Table 2) (Lindholm & Mork 1990, Sanders 1995, Levinsen et al 2000, Levinson & Nielsen 2002, Setälä & Kivi 2003. Peak population densities can be below its compensation depth for photoautotrophy (Crawford & Lindholm 1997 Stoecker et al (1989), Putt (1990b) Table 3.…”

Section: Ciliatesmentioning

confidence: 99%

Acquired phototrophy in aquatic protists

Stoecker¹,

Johnson²,

Vargas³

et al. 2009

Aquat. Microb. Ecol.

285

318

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“…In the Baltic Sea, natural ciliate cell densities range from less than 100 cells l -1 to over 40 × 10 3 cells l -1 (e.g. Setälä & Kivi 2003). Thus, in the mesocosms, the initial densities of small ciliates (173 and 153 × 10 3 cells l -1…”

Section: The Microbial Food Webmentioning

confidence: 99%

Transfer of nodularin to the copepod Eurytemora affinis through the microbial food web

Sopanen¹,

Uronen²,

Kuuppo³

et al. 2009

Aquat. Microb. Ecol.

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Nodularia spumigena Mertens ex Bornet & Flahault 1886 (Cyanophyceae) frequently forms harmful blooms in the Baltic Sea, and the toxin nodularin has been found in calanoid copepods during the blooms. Although nodularin has been found at higher trophic levels of the food web, no available information exists about the role of the microbial loop in the transfer of nodularin. We followed the transfer of nodularin to the copepod Eurytemora affinis during conditions that resembled initial 'pre-bloom' (Expt 1) and late stationary (Expt 2) phases of a N. spumigena bloom. The experiments were carried out using natural plankton communities spiked with cultured N. spumigena and grown in laboratory mesocosms, and E. affinis, which were isolated from the Baltic Sea and had no prior contact with nodularin. The plankton community was divided into 6 size fractions as follows: <150, < 45, < 20, <10, < 3 and < 0.2 µm, in which E. affinis was incubated for 24 h. Ingestion and clearance rates, food selection and faecal pellet production were based on microscopical analyses. Nodularin was measured with HPLC-MS with electrospray ionization in the copepods, as well as in dissolved and particulate fractions before and after incubation. We found that nodularin accumulated in copepods in all the plankton size fractions. The copepods contained nodularin concentrations of 14.3 ± 11.6 (mean ± SD) and 6.6 ± 0.7 pg ind.-1 after incubation in the <150 µm fraction in Expt 1 and Expt 2, respectively, while the range in the smaller size fractions was from 1.3 ± 2.8 to 5.7 ± 1.3 pg ind.-1 . Nodularin was transferred to the copepods through 3 pathways: (1) by grazing on filaments of small N. spumigena, (2) directly from the dissolved pool, and (3) through the microbial food web by copepods grazing on ciliates, dinoflagellates and heterotrophic nanoflagellates. The relative importance of direct grazing on small N. spumigena filaments varied from moderate to insignificant. The microbial loop was important in nodularin transfer to higher trophic levels. Our results suggest that the importance of the microbial loop in harmful algal bloom (HAB) toxin transfer may be underestimated both in marine and freshwater systems.

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Planktonic ciliates in the Baltic Sea in summer: distribution, species association and estimated grazing impact

Cited by 33 publications

References 50 publications

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

Acquired phototrophy in aquatic protists

Transfer of nodularin to the copepod Eurytemora affinis through the microbial food web

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