Description: Increases in atmospheric carbon dioxide (CO2) change ocean chemistry, as dissolved CO2 leads to a reduction in the seawater pH. Many marine taxa have been shown to be affected by ocean acidification; however, information on marine fungi is lacking. We analyzed the effect of pH on mycoplankton communities. The pH of microcosms was adjusted to a value mimicking the predicted ocean acidification in the near future. Fungal communities were analyzed using a double-marker gene approach, allowing a more detailed analysis of their response using 454 pyrosequencing. Mycoplankton communities in microcosms with in situ and adjusted water pH values differed significantly in terms of structure and diversity. The differences were mainly abundance shifts among the dominant taxa, rather than the exclusion of fungal groups. A sensitivity to lower pH values was reported for several groups across the fungal kingdom and was not phylogenetically conserved. Some of the fungal species that dominated the communities of microcosms with a lower pH were known pathogenic fungi. With the increasing awareness of the significant role fungi play in marine systems, including performing a diverse range of symbiotic activities, our results highlight the importance of including fungi in further research projects studying and modeling biotic responses to the predicted ocean acidification.

Description: The ingestion of microplastics has been shown for a great variety of marine organisms. However, benthic marine mesoherbivores such as the common periwinkle Littorina littorea have been largely disregarded in studies about the effects of microplastics on the marine biota, probably because the pathway for microplastics to this functional group of organisms was not obvious. In laboratory experiments we showed that the seaweed Fucus vesiculosus retains suspended microplastics on its surface. The numbers of microplastics that adhered to the algae correlated with the concentrations of suspended particles in the water. In choice feeding assays L. littorea did not distinguish between algae with adherent microplastics and clean algae without microplastics, indicating that the snails do not recognize solid nonfood particles in the submillimeter size range as deleterious. In periwinkles that were feeding on contaminated algae, microplastics were found in the stomach and in the gut. However, no microplastics were found in the midgut gland, which is the principle digestive organ of gastropods. Microplastics in the fecal pellets of the periwinkles indicate that the particles do not accumulate rapidly inside the animals but are mostly released with the feces. Our results provide the first evidence that seaweeds may represent an efficient pathway for microplastics from the water to marine benthic herbivores.

Description: The ingestion of microplastics has been shown for a great variety of marine organisms. However, benthic marine mesoherbivores such as the common periwinkle Littorina littorea have been largely disregarded in studies about the effects of microplastics on the marine biota, probably because the pathway for microplastics to this functional group of organisms was not obvious. In laboratory experiments we showed that the seaweed Fucus vesiculosus retains suspended microplastics on its surface. The numbers of microplastics that adhered to the algae correlated with the concentrations of suspended particles in the water. In choice feeding assays L. littorea did not distinguish between algae with adherent microplastics and clean algae without microplastics, indicating that the snails do not recognize solid nonfood particles in the submillimeter size range as deleterious. In periwinkles that were feeding on contaminated algae, microplastics were found in the stomach and in the gut. However, no microplastics were found in the midgut gland, which is the principle digestive organ of gastropods. Microplastics in the fecal pellets of the periwinkles indicate that the particles do not accumulate rapidly inside the animals but are mostly released with the feces. Our results provide the first evidence that seaweeds may represent an efficient pathway for microplastics from the water to marine benthic herbivores.

Description: Seasonal activities of the digestive enzyme trypsin were measured between August 1998 and May 1999 to study different nutritional strategies of the two copepods Pseudocalanus minutus and Oithona similis in the Arctic Kongsfjorden (Svalbard) using a highly sensitive fluorescence technique. Stage-, depth- and season-specific characteristics of digestive activity were reflected in the trypsin activity. P. minutus females and stage V copepodids (C) had highest trypsin activities in spring during reproduction (197.5 and 145.7 nmol min−1 ng C−1, respectively). In summer stages CIII–V and in autumn stages CIV and V had high activities (80–116 nmol min−1 ng C−1) in the shallow layer (〈 100 m) presumably as a consequence of prolonged feeding before descending to overwintering depth. Trypsin activities at depth (〉 100 m) in summer and autumn were low in stages CIII and CIV (29–60 nmol min−1 ng C−1) and in winter in all stages in both layers (20–43 nmol min−1 ng C−1). Based on low trypsin activity, males most likely did not feed. In O. similis, the spring phytoplankton bloom did not significantly affect trypsin activity as compared to the other seasons. O. similis CV and females had high trypsin activities in summer in the deep stratum (304.5 nmol min−1 ng C−1), which was concomitant with reproductive processes and energy storage for overwintering. In autumn, stage CV and female O. similis had significantly higher activities than stage CIV (130–152 versus 78 nmol min−1 ng C−1), which is in accordance with still ongoing developmental and reproductive processes in CVs and females. Comparisons of both species revealed different depth-related responses emphasizing different nutritional preferences: the mainly herbivorous P. minutus is more actively feeding in the shallow layer, where primary production occurs, whereas the omnivorous O. similis is not as much restricted to a certain depth layer, when searching for food. P. minutus had lower levels of trypsin activity during all seasons. In contrast to P. minutus, higher enzyme activities in males of O. similis suggest that they continue to feed and survive after fertilization of females.

Description: We discuss several forms of developmental plasticity exhibited by marine crabs, in the context of ecological developmental biology (EcoDevo), and seek to motivate research in EcoDevo by addressing some key questions of the field. We summarise the diversity of plastic developmental responses exhibited during crab development, identify gaps in knowledge and highlight the importance of EcoDevo research in the light of current climate change. Marine crabs show a suite of plastic responses including transgenerational plasticity (e.g., maternal effects), as well as developmental plasticity both within the larval phase and across the larval-juvenile life history transition (e.g., latent effects). Given the potential ecological and evolutionary consequences we think that there is much potential for research in the field of EcoDevo using brachyuran crabs as model organisms.

Description: Understanding organismal responses to environmental drivers is relevant to predict species capacities to respond to climate change. However, the scarce information available on intraspecific variation in the responses oversimplifies our view of the actual species capacities. We studied intraspecific variation in survival and larval development of a marine coastal invertebrate (shore crab Carcinus maenas) in response to two key environmental drivers (temperature and salinity) characterising coastal habitats. On average, survival of early larval stages (up to zoea IV) exhibited an antagonistic response by which negative effects of low salinity were mitigated at increased temperatures. Such response would be adaptive for species inhabiting coastal regions of freshwater influence under summer conditions and moderate warming. Average responses of developmental time were also antagonistic and may be categorised as a form of thermal mitigation of osmotic stress. The capacity for thermal mitigation of low-salinity stress varied among larvae produced by different females. For survival in particular, deviations did not only consist of variations in the magnitude of the mitigation effect; instead, the range of responses varied from strong effects to no effects of salinity across the thermal range tested. Quantifying intraspecific variation of such capacity is a critical step in understanding responses to climate change: it points towards either an important potential for selection or a critical role of environmental change, operating in the parental environment and leading to stress responses in larvae.

Description: We studied the role of oceanographic conditions and life history strategies on recovery after extinction in a metapopulation of marine organisms dispersing as pelagic larvae. We combined an age‐structured model with scenarios defined by realistic oceanographic conditions and species distribution along the Irish Sea coast (North Europe). Species life history strategies were modeled combining the dispersal behaviors with two levels of fecundity. Recovery times were quantified after simulating extinction in four regions. Two alternative strategies (high fecundity or larval tidal transport) led to short recovery times, irrespective of the effects of other drivers. Other strategies and low larval survival exacerbated the effects of oceanographic conditions on recovery times: longer times were associated with for example the presence of frontal zones isolating regions of extinction. Recovery times were well explained by the connectivity of each focal population with those located outside the area of extinction (which was higher in the so‐called small world topologies), but not by subsidies (direct connections with populations located nearby). Our work highlights the complexities involved in population recovery: specific trait combinations may blur the effects of the habitat matrix on recovery times; K‐strategists (i.e., with low fecundities) may achieve quick recovery if they possess the appropriate dispersal traits. High larval mortality can exacerbate the effect of oceanographic conditions and lead to heterogeneity in recovery times. Overall, processes driving whole network topologies rather than conditions surrounding local populations are the key to understand patterns of recovery.

Description: Dispersal and migration can be important drivers of species distributions. Because the paths followed by individuals of many species are curvilinear, spatial statistical models based on rectilinear coordinates systems would fail to predict population connectivity or the ecological consequences of migration or species invasions. I propose that we view migration/dispersal as if organisms were moving along curvilinear geometrical objects called smooth manifolds. In that view, the curvilinear pathways become the ‘shortest realised paths’ arising from the necessity to minimise mortality risks and energy costs. One can then define curvilinear coordinate systems on such manifolds. I describe a procedure to incorporate manifolds and define appropriate coordinate systems, with focus on trajectories (1D manifolds), as parts of mechanistic ecological models. I show how a statistical method, known as ‘manifold learning’, enables one to define the manifold and the appropriate coordinate systems needed to calculate population connectivity or study the effects of migrations (e.g. in aquatic invertebrates, fish, insects and birds). This approach may help in the design of networks of protected areas, in studying the consequences of invasion, range expansions, or transfer of parasites/diseases. Overall, a geometrical view to animal movement gives a novel perspective to the understanding of the ecological role of dispersal and migration.

Description: Intertidal serrated wrack Fucus serratus is common throughout the temperate N-Atlantic and plays an important role as a bioengineering species structuring lower intertidal communities. Several studies have addressed the impact of Fucus cover and its disturbance on species richness, diversity and succession of associated species in manipulative experiments. However, natural catastrophic events have scarcely been followed on a spatial mesoscale. We analyzed a 10-yrs time series on 140 permanent geo-referenced plots in the intertidal zone at the island of Helgoland (North Sea) covering an area of approx. 100 x 100 m. Samples were taken biannually in winter and summer. We describe the general intra- and interannual dynamics of F. serratus coverage and associated seaweed and mollusk species. The spatio-temporal extent and percentage coverage of F. serratus displayed a regular intra-annual pattern with lower coverage in winter than in summer whereas the spatial extent of the zone remained stable over many years. In winter 2006/2007 there was considerable loss of cover (from 100% to ≤30%), probably caused by several successive strong autumn and winter storms. Recovery of the F. serratus population required three vegetation periods. We will present data on the temporal co-variation of associated seaweed and mollusk species richness, evenness and diversity before and after the disturbance and discuss differences between investigations at different spatial scales.