Differential tolerance to cyanobacterial exposure between geographically distinct populations of Perca fluviatilis

High capacity for a dietary specialist consumer population to cope with increasing cyanobacterial blooms

We present a common-garden experiment to examine the amphipod Monoporeia affinis, a key deposit-feeder in the Baltic Sea, a low diversity system offering a good model for studying local adaptations. In the northern part of this system, the seasonal development of phytoplankton is characterized by a single diatom bloom (high nutritional quality), whereas in the south, the diatom bloom is followed by a cyanobacteria bloom (low nutritional quality) during summer. Therefore, the nutrient input to the benthic system differs between the sea basins. Accordingly, the amphipod populations were expected to be dietary specialists in the north and generalists in the south. We tested this hypothesis using a combination of stable isotope tracers, trophic niche analyses, and various endpoints of growth and health status. We found that when mixed with diatomes, the toxin-producing cyanobacteria, were efficiently incorporated and used for growth by both populations. However, contrary to expectations, the feeding plasticity was more pronounced in the northern population, indicating genetically-based divergence and suggesting that these animals can develop ecological adaptations to the climate-induced northward cyanobacteria expansion in this system. These findings improve our understanding regarding possible adaptations of the deposit-feeders to increasing cyanobacteria under global warming world in both limnic and marine ecosystems. It is possible that the observed effects apply to other consumers facing altered food quality due to environmental changes.

Correlating seasonal changes of naturally produced brominated compounds to biomarkers in perch from the Baltic Sea

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs), naturally produced by algae and cyanobacteria in the Baltic Sea, are potent disrupters of energy metabolism as well as endocrine disruptors and neurotoxins. In this study, European perch (Perca fluviatilis) from the Baltic Sea were sampled from May until October. OH-PBDEs and ten biomarkers were measured in each individual (n = 84 over 18 sampling time points) to study potential correlations between exposure to OH-PBDEs and changes in biomarkers. Several biomarkers showed significant non-linear seasonal variation. In the perch, ethoxyresorufin-O-deethylase (EROD) activity, plasma lactate concentration, and plasma glucose concentration showed a significant positive log-linear correlation with OH-PBDEs, whereas lipid percentage and liver somatic index showed a significant negative log-linear correlation with OH-PBDEs. These results strengthen the concern that OH-PBDEs could cause negative health effects for fish in the Baltic Sea.

The profound effect of harmful cyanobacterial blooms: From food-web and management perspectives

Sustainable and effective water management plans must have a reliable risk assessment strategies for harmful cyanobacterial blooms (HABs) that would enable timely decisions to be made, thus avoiding the trespassing of ecological thresholds, leading to the collapse of ecosystem structure and function. Such strategies are usually based on cyanobacterial biomass and/or on the monitoring of known toxins, which may, however, in many cases, under- or over-represent the actual toxicity of the HAB. Therefore, in this study, by the application of growth-inhibition assays using different bacteria, algae, zooplankton and fish species, we assessed the toxicological potential of two cyanobacterial blooms that differed in total cyanobacterial biomass, species composition and cyanopeptide profiles. We demonstrated that neither cyanobacterial community composition nor its relative abundance, nor indeed concentrations of known toxins reflected the potential risk of HAB based on growth-inhibition assays. We discuss our findings in the context of food-web dynamics and ecosystem management, and suggest that toxicological tests should constitute a key element in the routine monitoring of water bodies so as to prevent under-/over-estimation of potential HAB risk for both ecosystem and public health.

Chemical ecology of marine plankton

Covering: January 2013 to online publication December 2014This review summarizes recent research in the chemical ecology of marine pelagic ecosystems, and aims to provide a comprehensive overview of advances in the field in the time period covered. In order to highlight the role of chemical cues and toxins in plankton ecology this review has been organized by ecological interaction types starting with intraspecific interactions, then interspecific interactions (including facilitation and mutualism, host-parasite, allelopathy, and predator-prey), and finally community and ecosystem-wide interactions.