Abundance and biomass of gelatinous plankton in the southern part of the Black Sea in June 1991

Cruise 1991-06 conductucted covering TEEZ with a large cruise presents a dataset of macro gelatinous biomass and abundance in the Southern Black Sea in June 1991.

Seaweed - epiphyte - mesograzer communities were tested for their responses to elevated seawater temperature and [CO2] in benthic mesocosms experiments across four consecutive seasons of one year in Kiel, Germany

Rising seawater temperature and CO2 concentrations (ocean acidification) represent two of the most influential factors impacting marine ecosystems in the face of global climate change. In ecological climate change research full-factorial experiments across seasons in multi-species, cross-trophic level set-ups are essential as they allow making realistic estimations about direct and indirect effects and the relative importance of both major environmental stressors on ecosystems. In benthic mesocosm experiments we tested the responses of coastal Baltic Sea Fucus vesiculosus communities to elevated seawater temperature and CO2 concentrations across four seasons of one year. While increasing [CO2] levels only had minor effects, warming had strong and persistent effects on grazers which affected the Fucus community differently depending on season. In late summer a temperature-driven collapse of grazers caused a cascading effect from the consumers to the foundation species resulting in overgrowth of Fucus thalli by epiphytes. In fall/ winter, outside the growing season of epiphytes, intensified grazing under warming resulted in a significant reduction of Fucus biomass. Thus, we confirm the prediction that future increasing water temperatures influence marine food-web processes by altering top-down control, but we also show that specific consequences for food-web structure depend on season. Since Fucus vesiculosus is the dominant habitat-forming brown algal system in the Baltic Sea, its potential decline under global warming implicates the loss of key functions and services such as provision of nutrient storage, substrate, food, shelter and nursery grounds for a diverse community of marine invertebrates and fish in Baltic Sea coastal waters.

Compilation of scientific results of the OASIS project

Seamounts are of great interest to science, industry and conservation because of their potential role as 'stirring rods' of the oceans, their enhanced productivity, their high local biodiversity, and the growing exploitation of their natural resources. This is accompanied by rising concern about the threats to seamount ecosystems, e.g. through over-fishing and the impact of trawling. OASIS described the functioning characteristics of seamount ecosystems. OASIS' integrated hydrographic, biogeochemical and biological information. Based on two case studies. The scientific results, condensed in conceptual and mass balanced ecosystem models, were applied to outline a model management plan as well as site-specific management plans for the seamounts investigated. OASIS addressed five main objectives: Objective 1: To identify and describe the physical forcing mechanisms effecting seamount systems Objective 2: To assess the origin, quality and dynamics of particulate organic material within the water column and surface sediment at seamounts. Objective 3: To describe aspects of the biodiversity and the ecology of seamount biota, to assess their dynamics and the maintenance of their production. Objective 4: Modelling the trophic ecology of seamount ecosystems. Objective 5: Application of scientific knowledge to practical conservation.

Fauna composition of benthos communities in bottom sediments from the edge and the central part of the shelf in the California upwelling zone

Two shelf communities from the central part off the California Peninsula are described. The community of Amphiodia urtica - Nephtys ferruginea develops in the central part of the shelf within the depth range 95-105 m. The community of Nephtys ferruginea - Amphiura acrystata develops on the shelf edge at depth 110 m. Biomasses of both communities are very low (about 10 g/m**2). Species richness of the shelf community is high; more than 60 species occur in samples (43-51 species per a community). Various echinoderms and some other groups are abundant on the Californian shelf; these groups are absent in shelf areas of Peruvian and Benguela upwellings. Species structures of the communities were analyzed; the communities were shown to consist of coexisting, but not interacting guilds; this indicates that the communities are undersaturated with individuals. At the same time values of ABC-indices indicate that the communities are stable. We suggest that in this case adaptation to unfavorable but stable environment is observed (selection of species-stressolarents). An explanation seems to lie in the penetrating type of the upwelling in the Californian upwelling zone. Low biomass values seem to result from mass development of necto-benthic carnivorous crustaceans-galateids Pleuroncodes planiceps.