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Responses of phyto- and zooplankton communities to Prymnesium polylepis (Prymnesiales) bloom in the Baltic Sea.

Gorokhova E, Hajdu S, Larsson U - PLoS ONE (2014)

Bottom Line: The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008.Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA:DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton.Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden; Department of Applied Environmental Science, Stockholm University, Stockholm, Sweden.

ABSTRACT
A large bloom of Prymnesium polylepis occurred in the Baltic Sea during the winter 2007-spring 2008. Based on numerous reports of strong allelopathic effects on phytoplankton exerted by P. polylepis and its toxicity to grazers, we hypothesized that during this period negative correlations will be observed between P. polylepis and (1) main phytoplankton groups contributing to the spring bloom (i.e., diatoms and dinoflagellates), and (2) zooplankton growth and abundance. To test these hypotheses, we analyzed inter-annual variability in phytoplankton and zooplankton dynamics as well as growth indices (RNA:DNA ratio) in dominant zooplankton in relation to the Prymnesium abundance and biomass. Contrary to the hypothesized relationships, no measurable negative responses to P. polylepis were observed for either the total phytoplankton stocks or the zooplankton community. The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008. Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA:DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton. Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce.

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Differences in phytoplankton biovolumes (mm3 L−1) in January-June between the year 2008 and 2007.Abbreviations: DIAT - Diatoms, DINO - Dinoflagellates, PRYM - Prymnesiales. Stations are ordered south to north.
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pone-0112985-g003: Differences in phytoplankton biovolumes (mm3 L−1) in January-June between the year 2008 and 2007.Abbreviations: DIAT - Diatoms, DINO - Dinoflagellates, PRYM - Prymnesiales. Stations are ordered south to north.

Mentions: For most stations, higher total phytoplankton biovolumes were observed in 2008 than in 2007, with significant differences mainly for the winter-spring period (Table 1; Figure 2). At stn B1, the yearly mean biovolume was more than doubled in 2008 compared to 2007 (0.50 vs. 0.22 mm3 L−1); moreover, ∼30% difference remained when P. polylepis was excluded (0.30 vs. 0.19 mm3 L−1). In winter-spring, diatoms at all stations, except stn BY2, had higher biovolume in 2008 than in 2007, with overall significant difference between the years (t5 = 5.49, p<0.003), while the opposite was observed for dinoflagellates that were generally lower (t5 = 3.91, p<0.02; Figure 3). The diatom response was associated with a general increase in Thalassiosira species observed at all stations and, to some extent, Skeletonema costatum that was higher in the central Baltic proper and the Bornholm basin but lower in the northern Baltic proper (Figure S2). Another algae that were consistently more abundant in 2008 than in 2007 were the euglenoid flagellates Eutreptiella spp. and some dinoflagellates from the order Peridiniales (Figure S2). However, other species of this order, such as the chain-forming, spring dinoflagellate Peridiniella catenata, showed consistently lower values in 2008 (Figure S2), contributing strongly to the observed decrease in total dinoflagellate stocks during the Prymnesium bloom. When values from the year 2008 were compared to the long-term means for the stations in the northern Baltic proper, the group-specific biovolumes were mostly within the 25–75% range of the long-term variability (Figure 4), except dinoflagellates at stn BY31, where the 2008 values were significantly lower than the long-term mean, both on the yearly basis (t16 = 7.99, p<0.0001) and for the January-June period (t16 = 7.27, p<0.0001).


Responses of phyto- and zooplankton communities to Prymnesium polylepis (Prymnesiales) bloom in the Baltic Sea.

Gorokhova E, Hajdu S, Larsson U - PLoS ONE (2014)

Differences in phytoplankton biovolumes (mm3 L−1) in January-June between the year 2008 and 2007.Abbreviations: DIAT - Diatoms, DINO - Dinoflagellates, PRYM - Prymnesiales. Stations are ordered south to north.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231118&req=5

pone-0112985-g003: Differences in phytoplankton biovolumes (mm3 L−1) in January-June between the year 2008 and 2007.Abbreviations: DIAT - Diatoms, DINO - Dinoflagellates, PRYM - Prymnesiales. Stations are ordered south to north.
Mentions: For most stations, higher total phytoplankton biovolumes were observed in 2008 than in 2007, with significant differences mainly for the winter-spring period (Table 1; Figure 2). At stn B1, the yearly mean biovolume was more than doubled in 2008 compared to 2007 (0.50 vs. 0.22 mm3 L−1); moreover, ∼30% difference remained when P. polylepis was excluded (0.30 vs. 0.19 mm3 L−1). In winter-spring, diatoms at all stations, except stn BY2, had higher biovolume in 2008 than in 2007, with overall significant difference between the years (t5 = 5.49, p<0.003), while the opposite was observed for dinoflagellates that were generally lower (t5 = 3.91, p<0.02; Figure 3). The diatom response was associated with a general increase in Thalassiosira species observed at all stations and, to some extent, Skeletonema costatum that was higher in the central Baltic proper and the Bornholm basin but lower in the northern Baltic proper (Figure S2). Another algae that were consistently more abundant in 2008 than in 2007 were the euglenoid flagellates Eutreptiella spp. and some dinoflagellates from the order Peridiniales (Figure S2). However, other species of this order, such as the chain-forming, spring dinoflagellate Peridiniella catenata, showed consistently lower values in 2008 (Figure S2), contributing strongly to the observed decrease in total dinoflagellate stocks during the Prymnesium bloom. When values from the year 2008 were compared to the long-term means for the stations in the northern Baltic proper, the group-specific biovolumes were mostly within the 25–75% range of the long-term variability (Figure 4), except dinoflagellates at stn BY31, where the 2008 values were significantly lower than the long-term mean, both on the yearly basis (t16 = 7.99, p<0.0001) and for the January-June period (t16 = 7.27, p<0.0001).

Bottom Line: The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008.Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA:DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton.Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden; Department of Applied Environmental Science, Stockholm University, Stockholm, Sweden.

ABSTRACT
A large bloom of Prymnesium polylepis occurred in the Baltic Sea during the winter 2007-spring 2008. Based on numerous reports of strong allelopathic effects on phytoplankton exerted by P. polylepis and its toxicity to grazers, we hypothesized that during this period negative correlations will be observed between P. polylepis and (1) main phytoplankton groups contributing to the spring bloom (i.e., diatoms and dinoflagellates), and (2) zooplankton growth and abundance. To test these hypotheses, we analyzed inter-annual variability in phytoplankton and zooplankton dynamics as well as growth indices (RNA:DNA ratio) in dominant zooplankton in relation to the Prymnesium abundance and biomass. Contrary to the hypothesized relationships, no measurable negative responses to P. polylepis were observed for either the total phytoplankton stocks or the zooplankton community. The only negative response, possibly associated with P. polylepis occurrence, was significantly lower abundance of dinoflagellates both during and after the bloom in 2008. Moreover, contrary to the expected negative effects, there were significantly higher total phytoplankton abundance as well as significantly higher winter abundance and winter-spring RNA:DNA ratio in dominant zooplankton species in 2008, indicating that P. polylepis bloom coincided with favourable feeding conditions for zooplankton. Thus, primary consumers, and consequently also zooplanktivores (e.g., larval fish and mysids), may benefit from haptophyte blooms, particularly in winter, when phytoplankton is scarce.

Show MeSH
Related in: MedlinePlus