Allelopathic effects of Baltic Sea spring bloom dinoflagellates on co-occurring phytoplankton

Abstract

Dinoflagellate-dominated spring blooms are globally uncommon, but they regularly occur and are even increasing in the Baltic Sea, varying interannually in importance with diatomdominated blooms. The success of dinoflagellates in the spring phytoplankton community has remained poorly understood, as they are expected to be inferior competitors due to their low growth rates and nutrient uptake capacities under nutrient-replete spring conditions. To prevail in the phytoplankton community, dinoflagellates must either be favored by specific environmental settings or possess adaptations, such as allelopathy, to compensate for their competitive disadvantage. Using batch cultures, we studied the allelopathic effects of 3 dominant vernal dinoflagellates -Biecheleria baltica, Gymnodinium corollarium and Scrippsiella hangoei -on 5 typical spring bloom diatoms and 1 cryptophyte. We also tested the effects of the dinoflagellates on each other. Three of the 5 diatoms -Melosira arctica, Skeletonema marinoi and Thalassiosira balticawere significantly inhibited by cell-free filtrates or live cells of all dinoflagellates. Chaetoceros cf. wighamii and Diatoma tenuis were suppressed by G. corollarium, and D. tenuis was also suppressed by live cells of S. hangoei. In contrast, the cryptophyte Rhodomonas sp. was stimulated by all dinoflagellate species. The effects of dinoflagellate filtrates on other dinoflagellate species were mostly positive, but co-culturing tended to inhibit the growth of the respective target dinoflagellates. As some of the major players of the diatom spring bloom can be suppressed by cooccurring dinoflagellates in culture, we conclude that allelopathy may be one mechanism by which vernal dinoflagellates frequently outcompete diatoms and form intense spring blooms.

Spring bloom community change modifies carbon pathways and C : N : P : Chl <i>a</i> stoichiometry of coastal material fluxes

“…Dinoflagellates have been shown to possess compensatory strategies to compete with fast-growing phytoplankton groups, such as allelopathy, mixotrophy, and internal nutrient storages (Legrand and Carlsson, 1998;Collos et al, 2004;Tillmann et al, 2008). B. baltica has recently been confirmed to effectively suppress growth of co-occurring diatoms by excretion of allelochemicals (Suikkanen et al, 2011), and utilization of residual P has been suggested to facilitate sustained growth of B.baltica in the 2004 mesocosms (Kremp et al, 2008).…”

Allelopathic effects of Alexandrium fundyense (Dinophyceae) on Thalassiosira cf. gravida (Bacillariophyceae): a matter of size

“…, Hattenrath‐Lehmann and Gobler , Suikkanen et al. ), and are influenced by abiotic (e.g., light, temperature, nutrient availability) and biotic (e.g., growth stage, presence or absence of bacteria) factors (Kubanek et al. , Granéli et al.…”

“…Much of what we know about allelopathy in phytoplankton comes from studies on harmful species (e.g., Arzul et al 1999, Schmidt and Hansen 2001, Kubanek et al 2005, Tang and Gobler 2010. These studies illustrate the complex nature of these interactions, showing that both production of and responses to allelopathic compounds vary greatly between and within species (Gran eli et al 2008, Poulson et al 2010, Hattenrath-Lehmann and Gobler 2011, Suikkanen et al 2011, and are influenced by abiotic (e.g., light, temperature, nutrient availability) and biotic (e.g., growth stage, presence or absence of bacteria) factors (Kubanek et al 2005, Gran eli et al 2008, Prince et al 2008a, Poulson et al 2010, Yamasaki et al 2011. Cell concentrations of both the allelopathic species and its "targets," as well as the duration of exposure to exudates, appear to play important roles in determining outcomes of allelopathic interactions, suggesting that the responses are dose-dependent (Tillmann et al 2007, Poulson et al 2010, Tang and Gobler 2010.…”

Spring phytoplankton communities shaped by interannual weather variability and dispersal limitation: Mechanisms of climate change effects on key coastal primary producers

“…With optimal salinity (6 to 20) and temperature (0uC to 6uC) ranges (Kremp et al 2005) and massive resting cyst production (Kremp and Heiskanen 1999;Olli and Trunov 2010), it is well adapted to the Baltic Sea spring bloom conditions. The recently described Gymnodinium corollarium Sundströ m, Kremp & Daugbjerg (Sundströ m et al 2009) dominates the spring bloom in the open Baltic Proper, but also inhabits coastal waters in the northern Baltic Proper (Suikkanen et al 2011). Scrippsiella hangoei (Schiller) Larsen is a minor component of the spring bloom.…”