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

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

Sucrose-induced shrinkage of in vitro produced bovine morulae: Effect on viability, morphology and ease of evaluation

Sucrose (0.3 M) was used to cause artificial compaction of the embryonic cell mass of in vitro produced bovine embryos to facilitate morphological evaluation. Embryos were produced using routine in vitro maturation (IVM) and fertilization (IVF) techniques. The time necessary to induce shrinkage in 0.3 M sucrose to 75% of the original volume of Day 5 morulae was found to be less than 1 min, and 95% of the volume was regained in PBS after 2.5 min. No detrimental effect was observed after a 5- to 10-min sucrose treatment on subsequent blastocyst formation at Days 6 and 7 (P> 0.05). Furthermore, no significant differences were observed in the total number of cells, or in the mitotic and pycnotic cell index of blastocysts in different treatment groups. Agreement among 7 evaluators grading 40 Day 6 embryos was examined using the kappa coefficient of agreement (kappa). Overall agreement among evaluators for classification of quality grade was poor (48.2 %, kappa = 0.31) for embryos evaluated in PBS, but the rate improved when the same embryos were scored in sucrose (62.5 %, kappa = 0.49). Evaluating less compact in vitro produced bovine morulae in sucrose increases agreement among evaluators, since embryos in sucrose mimick the appearance of in vivo produced embryos. Thus, we conclude that scoring in vitro produced embryos in sucrose improves agreement among evaluators

New climatic targets against global warming: will the maximum 2 degrees C temperature rise affect estuarine benthic communities?

The Paris Agreement signed by 195 countries in 2015 sets out a global action plan to avoid dangerous climate change by limiting global warming to remain below 2 degrees C. Under that premise, in situ experiments were run to test the effects of 2 degrees C temperature increase on the benthic communities in a seagrass bed and adjacent bare sediment, from a temperate European estuary. Temperature was artificially increased in situ and diversity and ecosystem functioning components measured after 10 and 30 days. Despite some warmness effects on the analysed components, significant impacts were not verified on macro and microfauna structure, bioturbation or in the fluxes of nutrients. The effect of site/ habitat seemed more important than the effects of the warmness, with the seagrass habitat providing more homogenous results and being less impacted by warmness than the adjacent bare sediment. The results reinforce that most ecological responses to global changes are context dependent and that ecosystem stability depends not only on biological diversity but also on the availability of different habitats and niches, highlighting the role of coastal wetlands. In the context of the Paris Agreement it seems that estuarine benthic ecosystems will be able to cope if global warming remains below 2 degrees C.The authors would like to thank P. Cardoso, S. Leston e M. D'Ambrosio who helped in field and laboratorial work. This research was supported by FCT (Portuguese Foundation for Science and Technology), through the grants attributed to D Crespo (SFRH/BD/80252/2011), T F Grilo (SFRH/BPD/98590/2013), J P Coelho (SFRH/BPD/102870/2014), I Fernandes (SFRH/BPD/97656/2013), to Investigador FCT programme attributed to M. Dolbeth (IF/00919/2015) and BIOCHANGED project (PTDC/MAR/111901/2009), subsidized by the European Social Fund and MCTES (Portuguese Ministry of Science, Technology and Higher Education), through the POPH (Human Potential Operational Programme), QREN (National Strategic Reference Framework) and COMPETE (Programa Operacional Factores de Competitividade). Thanks are also due, for the financial support to CESAM (UID/AMB/50017/2013), to FCT/MEC through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020.info:eu-repo/semantics/publishedVersio