DOI: 10.5061/dryad.d0826
title: Data from: Rehabilitating the cyanobacteria – niche partitioning, resource use efficiency, and phytoplankton community structure during diazotrophic cyanobacterial blooms

description: 1. Blooms of nitrogen-fixing cyanobacteria are recurrent phenomena in
 marine and freshwater habitats, and their supplying role in aquatic
 biogeochemical cycles is generally considered vital. The objective of this
 study is to analyze if an increasing proportion of nitrogen-fixing
 cyanobacteria affects (i) the composition of the non-diazotrophic
 component of ambient phytoplankton communities, and (ii) resource use
 efficiency (RUE; ratio of chl a to total nutrients) – an important
 ecosystem function. We hypothesize that diazotrophs increase community P
 use, and decrease N use efficiencies, as new N is brought into the system,
 relaxing N, and concomitantly aggravating P limitation. We test this by
 analyzing an extensive dataset from the Baltic Sea (&gt; 3700
 quantitative phytoplankton samples), known to harbor conspicuous and
 recurrent blooms of Nodularia spumigena and Aphanizomenon sp. 2.
 System-level phosphorus use efficiency (RUEP) was positively related with
 high proportion of diazotrophic cyanobacteria, suggesting aggravation of
 phosphorus limitation. However, concomitant decrease of nitrogen use
 efficiency (RUEN) was not observed. Nodularia spumigena, a dominant
 diazotroph and a notorious toxin producer, had a significantly stronger
 relationship with RUEP, compared to the competing non-toxic Aphanizomenon
 sp., confirming niche differentiation in P acquisition strategies between
 the major bloom-forming cyanobacterial species in the Baltic Sea.
 Nodularia occurrences were associated with stronger temperature
 stratification in more offshore environments, indicating higher reliance
 on in situ P regeneration. 3. By using constrained and unconstrained
 ordination, permutational multivariate analysis of variance, and local
 similarity analysis, we show that diazotrophic cyanobacteria explained no
 more than a few percent of the ambient phytoplankton community variation.
 The analyses furthermore yielded rather evenly distributed negative and
 positive effects on individual co-occurring phytoplankton taxa, with no
 obvious phylogenetic or functional trait-based patterns. 4. Synthesis. Our
 study reveals that despite the widely acknowledged noxious impacts of
 cyanobacterial blooms, the overall effect on phytoplankton community
 structure is minor. There are no predominantly positive or negative
 associations with ambient phytoplankton species. Species-specific niche
 differences in cyanobacterial resource acquisition affect important
 ecosystem functions, like biomass production per unit limiting resource.
description: community data
 matrixSamples are in rows,
 species in columns, matrix values contain wet weight biomass. Note the
 many zeros of a typical community matrix.community.txtfunctional traits of phytoplankton speciesspecies in rows, traits in columns: nfix - nitrogen fixing ability; silica - silica cell wall; motility - possession of flagella; buoyancy - buoyancy regulation with gas vesicles; heterotrophy - ability of heterotrophic nutritional model; autotrophy - ability of autotrophic nutritional mode; fyco - possession of phycobilins; chlb - possession of chlorophyll b; chlc - possession of chlorophyll c; radius - cell size (radius) in μm; chain - ability to form chains or coloniesfd.txtsamples tableSamples in rows. Row-names are arbitrary sample codes, which match the row-names of the community matrix. Columns are: "lat" - latitude; "lon" - longitude; "obstime" - sampling date; "basin" - Baltic Sea basin; "dist" - distance from the shoreline (km); "Temp" - sample temperature (°C); "Salin" - salinity; "RUEP" - Phosphorus use efficiency; "RUEN" - Nitrogen use efficiency; "ww" - total phytoplankton wet weight (μg/L); "ww.fixers" - wet weight of nitrogen fixers (μg/L); "ww.apha" - wet weight of Aphanizomenon; "ww.nodu" - wet weight of Nodulariasamples.txtphylogeny filephylogeny file in Newick format. See http://en.wikipedia.org/wiki/Newick_format for format details. Can be read with read.tree function of the ape library in R software.phylogeny.txt