The Centre for Scientific Diving coordinates the Helmholtz large-scale infrastructure projects COSYNA, ACROSS and MOSES at AWI and represents the AWI in the Helmholtz-Portfolio Topic “Natural Disasters and Warning Systems” (NDWS). Within the AWI-HZG research program PACESII, the CSD is located in Topic 2 (Fragile Coasts).

The Centre for Scientific Diving is also the home of the working group "In situ ecology" which is part of the AWI section "Coastal Ecology". The working group focuses on environment-species interactions in polar and temperate coastal ecosystems with a strong interest in the effects of climate change, local anthropogenic impacts and natural challenges on the shallow water macro-zoobenthos and fish communities. We use a broad range of field methods spanning from classical net fishing over scientific diving based assessment methods up to the development and operation of cabled underwater observatories for long term monitoring approaches. Even though we also perform lab studies, the main focus of our research work at the CSD is in situ with diving as the main tool for our scientific work under water.

Coastal regions are favoured habitats for humankind with more than half of the world’s population living less than 50 kilometres away from the sea. Due to the increasing effects of global change, many of these areas are increasingly threatened by extreme events like strong storm surges and floodings. Recent prognoses project a significant increase of extreme meteorologic events also in the North Atlantic for the second half of the 20^th century with a progressive trend. Within these climate prognoses and scenarios, coastal defence becomes increasingly important for the protection of our coastlines. A good example for this development is the North Sea, were more than 80 % of the coastline is already artificially protected.

In 2010, the Centre for Scientific Diving of the AWI has installed an underwater experimental field North of Helgoland called MarGate to study the impacts of artificial structures on the demersal fish and macroinvertebrate communities on in the subtidal zone. 36 tetrapods (four-footed concrete breakwaters) with a weight of 6 tones each have been installed in 5 and 10 m water depth to investigate the effects of these structures on the local fauna. Since then, a variety of Bachelor-, Master- and PhD studies have been conducted in the CSD aiming at a better understanding of the interactions and functional relationships between sublittoral artificial structures and the resident fish and macro-invertebrate community.

Publications - see publication list of AWI Centre for Scientific Diving.

Arctic coastal systems are of special interest to climate coastal research due to their high sensibility to global warming. The Kongsfjorden ecosystem at en 79°N / 9°E in Spitsbergen (Fig. 1) is one of the best studied Arctic fjord systems on the Northern hemisphere with a ecological research history of more than 50 years.

The Kongsfjorden sublittoral area is characterized by flats of sand and gravel intermitted by rocky substratum often covered with dense stands of macro algae. These algae create complex habitats with a highly diverse macrozoobenthos and fish community. Our research work in the Kongsfjorden ecosystem focus on the quantitative assessment of the littoral fish community at different sites in the fjord ecosystem. Combining classic fish ecological studies (fyke net catches, mark-recapture experiments, stomach and otolith analysis) with a new state-of-the-art 3D underwater optical monitoring approaches (see AWIPEV-COSYNA observatory), we aim at a better understanding of the temporal and spatial distribution and the functional relationships between fish and environment in this polar fjord system.

Publications: see publication list of AWI Centre for Scientific Diving.

COSYNA is an observing system comprising several land and sea-based sensor systems in the North Sea and in the Arctic. The AWI contributes to COSYNA with two cabled underwater observatories in the North Sea (Helgoland) and in the Arctic (Kongsfjord Spitzbergen). Both systems are part of the Helmholtz Observatory Projects ACROSS and the EU-Project JERICO+.

-> Link to COSYNA@AWI

Publications: see publication list of AWI Centre for Scientific Diving.

During an expedition to Neumayer III, the AWI scientific diving team discovered unknown sessile anthozoans colonizing the sub-ice platelet layer in Atka Bay. The existence of higher sessile life forms in this dynamic habitat indicates an extraordinary organismal plasticity, but theories revolving around the anthozoan’s livelihood remain elusive. A missing key prerequisite is the lack of information on sub-ice platelet layer functioning and connectivity through the inaccessibility and variable nature of the ecosystem. We propose a novel, interdisciplinary system study to investigate Antarctica’s sub-ice platelet layer dynamics and attendant geno- and phenotypic capabilities of its biosphere. Central to the success of the project are the development of in situ approaches through diving and custom-designed incubation systems or sensor arrays. The project links expertise from physics and ecology, and employs techniques ranging from census-based surveys, monitoring, and in situ experiments to biogeochemical and molecular work. The results facilitate future (under-ice) research from Neumayer III, disclose unique and unknown strategies of adaptation and survival in extreme habitats, lead to a better integration of the sub-ice platelet layer ecosystem into Antarctic research efforts, and contribute to the strategic objectives of PACES and other AWI research consortia.

Publications: see publication list of AWI Centre for Scientific Diving.

In many fish species, group formation has been shown as important behavioural strategy to increasing the individual fitness. Previous work of Fischer & Hofmann (2004) as well as Fischer & Reyjol (2006) clearly demonstrated, that group formation especially in nocturnal benthic fish species significantly increase foraging efficiency, reduces predation risk and finally may lead to a significant increase in somatic growth.

Such a performance enhancement implies, that group members do exchange information among conspecifics, leading to an individual advantage compared to solitaire living fish. Besides optical and chemical communication, it is well known that many fish, i.e. cod species but also many others (in total > 1000 species) do communicate on an acoustic basis (Rountree 2003).

So far known reasons for sound production in fish are:

• Aggression (to defend resources against conspecifics or other species)
• Spawning activity (courtship behaviour)
• Foraging (to enhance intraspecific foraging success)
• Schoaling and group adherence (to reduce predation risk)
• Warning signals (intraspecific communication)

In this project our group together with the University of Applied Science (Prof. Dr. Steffen Reith) perform lab experiments on diel patterns of acoustic communication in fish using the sea robin (Trigla lucerna) as model organism for acoustic active fish.

Publications: see publication list of AWI Centre for Scientific Diving.