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The effects of stratospheric ozone depletion and of global warming on the marine biosphere are still underexplored, especially in the Arctic. Seaweeds are very important primary producers but are strongly susceptible to enhanced UV radiation and elevated temperatures, especially their spores. The UV susceptibility of spores has previously been invoked to determine the depth distribution of seaweeds. Therefore, we will investigate the effect of different radiation and temperature conditions on the ultra-structure, physiology and biochemistry of spores from various brown and green algae growing in different water depths. Moreover, we will study competition between zoospores of various species of brown macroalgae in order to get an insight about biotic factors structuring seaweed communities and also to explain more clearly the present seaweed zonation pattern.
The aim is to study the diversity and function of marine bacteria closely associated with marine sponges. The special character of life strategy of the community (symbiosis – commensalism), with special emphasis to the identity and the recruitment of bacteria during live cycle of the sponges will be described.
Since nearly all microalgae are associated with bacteria and some harbor intracellular bacteria, it is most likely that these bacteria are involved in the development or termination of natural occurring plankton assemblages. The diversity and development of associated bacteria in microalgae cultures and during phytoplankton succession will be described by molecular analysis of the bacterial community structure and by phylogenetic analysis of involved microorganisms.
Little is known about the consistency or phylogenetic affiliation of accociated intra- or extracellular bacterial populations in Echinodermata. Because certain taxa harbour bacteria and other not, these associations are presumably originated by coevolution and not by ecological circumstances. The intestine of echinodermata is populated by huge amounts of bacteria. Due to the different feeding strategy of echinoderms it is controversly discussed whether these bacteria are passively taken up or if they are permanently present. Hence it will be possible to elucidate if vertical transmission occurs or bacteria are recruted. With the knowledge of phylogenetic affiliations of microbial symbionts and their distribution (or localization) in different hosts, the physiological/biochemical status of the association will be investigated. The main emphasis will be the characterization of the in situ situation by adequate histological techniques (crysectioning) and “passive” (FT-IR) or “active” chemical imaging (confocal imaging, using fluorescent enzyme substrates or physiological dyes). The main experimental work in this WP bases on the creation of 16S-rDNA sequence libraries of echinoderrm associated bacteria (SCB & intestinal). Signature sequences will be analyzed and specific gene probes will be designed and applied.
The main research goal of this project is focused on trophic interactions within microbenthic communities in aquatic systems. Grazer-microalgae interactions are investigated by conducting field and laboratory experiments in order to get a closer idea of the microphytobenthos community structure itself. Especially the role of morphological and physiological adaptations of microalgae in the presence of specific meio- and macrofaunal predators are of great interest. In addition to that we have devised a new benthic sensor for the quantitative and qualitative assessment in situ of diverse populations of microphytobenthos with high spatial and temporal resolution, enabling rapid evaluation of the community structure and distribution.
HIMOM will aim to provide a system of methods, the so-called Hierarchical Monitoring Methods (or HMM), to determine system status and changes which are expressed by biological and physical variations within inter-tidal areas. The HMM will aim to provide a management strategy tailored to the needs of End User involved in activities relating to the sustainable development of tidal flat areas around Europe. The HMM system will represent a hierarchical suite of activities, ranging from simple ground measurements of biota and physical characteristics to remote sensing of spectral reflectance properties for the analysis of basin scale systems.
To study the organisms involved in phytoplankton succession and the Key factors involved. This includes Bacteria-Algae, Algae-zooplankton and Zooplankton-Fish interactions. Aspects such as algal-grazer defence mechanisms and digestability of alage are core topics.
Cellphysiological investigations of the effects of marine secondary metabolites on isolated (sensory) cells
The succession of macro- and microalgal communities in the Antarctic will be investigated in field experiments under various UV radiation (UVR) conditions and in the absence or presence of grazers. The observed differences in the succession process will be correlated to physiological traits of single species, especially in spores and germlings, which are the most vulnerable stages in their life histories. Photosynthetic activity of the different developmental stages will be measured routinely. Additionally we plan the determination of pigment composition, C:N ratios, content of UV protective pigments and of possible DNA damage. The experiments will start in spring, concomitant to the time of highest UVBR, due to the seasonal depletion of the ozone layer in the Antarctic region. Supplemental laboratory experiments will be conducted to determine the effects of UVR on spores and germlings of individual species. In addition to the above analyses, we plan to examine of UVR induced damage of cell fine structure and of the cytoskeleton. The results of both the field and laboratory experiments will allow us to predict the consequences of enhanced UVR for the diversity and stability of the algal community.
Marine invertebrates have highly active digestive enzymes which can exhibit extraordinary catalytical properties with respect to specificity, turnover performance and thermal stabilty. Highly specific bio-active substances are important for various biotechnological applications. The project is aimed to investigate the catalytic properties of digestive enzymes in marine invertebrates from a wide geographical and thus ecological range. Target species will be preferably crustaceans and echinoderms.
Marine invertebrates show a large variety of feeding strategies. These comprise mechanisms for catching prey, the uptake of food and the utilisation of various food sources. Morphological and anatomical adaptations allow for the capture and the ingestion of the food. However, the organism's physiological properties are the key for the efficient digestion, the nutrient uptake and the assimilation of food. In response to environmental factors marine organisms have developed highly specialised biochemical adaptations which are particularly reflected by the immeasurable diversity of digestive enzymes. The detailed function of digestive enzymes in marine invertebrates and, particularly, their synergistic interplay is still poorly understood.The overall aim is to investigate the mechanisms of enzymatic food utilisation and enzyme induction in different taxa of marine invertebrates in response to environmental factors.
Detection of UV-B induced DNA damage on zoospores of brown algae
Observation how UV-radiation affects recruitment on hard substrate in the upper sublitoral zone.
This study will be designed to determine the response mechanisms of representative species of macrophytes along the tide flat to provide the physiological basis for answers for ecological questions, in particular how the community structure of various beds of macroalgae from the intertidal to the subtidal (eulittoral to sublittoral) region of the coastal ecosystem is affected by enhanced UV radiation. In situ measurement of photosynthetic efficiency, growth, community structure and succession will be conducted to investigate how do different species of macrophytes respond to changes in the light environment over a depth gradient and across seasons of the year. It is hypothesized that the differences in the ability to tolerate stress are the main factors controlling the distribution pattern of macrophytes. With the limited understanding in the control of tolerance, elucidating the mechanism of stress in the physiology and ecology of the organisms will allow us to quantify the impediments encountered by organisms inhabiting the tide flats. Objectives: 1. To measure the daily and seasonal variation in photosynthetically active and ultraviolet radiation. 2. To characterize the macrophyte community structure of the coastal habitat. 3. To perform UV exclusion and UV supplementation experiments in order to assess its effect on the growth of some macrophyte species in the field and in mesocosms. 4. To assess the prevention of UV damage in selected macroalgae by production of sunscreen pigments. 4. To determine the recruitment rate, recolonization pattern and succession under PAR and varying UVR condition.
Due to its high energy, UV radiation can induce severe damage at the molecular and cellular level. On the molecular level proteins and lipids, as well as nucleic acids are particularly affected. Conformation changes of certain proteins involved in photosynthesis, such as the reaction center protein (D1) of photosystem II or the CO2 fixing enzyme in the Calvin cycle (RuBisCo) lead to an inhibition of photosynthesis, and consequently to a decrease in biomass production. This might shift certain algal species into deeper waters, not reached by UV radiation. The aim of the studies is to demonstrate how strong an increase of UV radiation due to stratospheric ozone depletion will influence the depth distribution and biomass production of macroalgae, and which molecules and processes are most severely affected. Moreover, it will be studied, which stage in the life cycle of the individual species is most sensitive to UV radiation as it will be this particular stage, which in the end determines the upper distribution limit of a certain species on the shore.