Division

Meiofauna is not only defined by its small body size between 32 µm and 1 mm. These organisms also differ from the larger macrofauna by their way of life and their reproductive strategies. Their role in the ecosystem “seabed” from the tidal areas to the deep sea is comparable to the role of microorganisms in the garden soil or in compost. They are decomposers and users of all organic material that accumulates at the seafloor. But there are also predatory representatives in the many animal groups that make up the meiofauna.

Nematodes, copepods, kinorhynchs, ostracods, gastrotrichs, and loriciferans are only some of the groups found in the meiofauna. The composition of the communities is strongly dependent on the environmental conditions in the respective habitat. Sediment grain size, oxygen content and food availability are reflected in the communities. We aim to investigate the ecological circumstances that lead to differences in communities and the function of meiofauna in different marine ecosystems.

The reliable identification of species is only possible on the basis of good descriptions. Since only few species of benthic copepods are known from the deep sea, we dedicate a large part of our work to the detailed description of new species of the order Harpacticoida. With the samples collected worldwide during the Census of Marine Life project CeDAMar we are able to further investigate the large scale distribution patterns of deep-sea copepods.

Especially in polar regions global warming has dramatic effects. Even at the bottom of the sea these changes are visible: glacial melting creates newly ice-free areas and the input of sediments into shallow water systems changes the environment. This can lead to changes in the sediment and shifts in community composition.

Species composition and colonization potential of the 
meiofauna in the Arctic and the Antarctic can thus be good indicators for climate change.

In the Antarctic deep sea we studied for the first time the sediment depth distribution of the meiofauna before and after a phytoplankton bloom.During the expedition ANDEEP-SYSTCO we found out that the individual density of the meiofauna is enhanced at the sediment surface after the food input from the photic zone.

The Arctic science village of Ny Ǻlesund is located at Kongsfjorden (Spitzbergen) where the German Alfred-Wegener- Institute for Polar and Marine Research and the French Institut Polaire Français Paul Emile Victor run the AWIPEV station. In cooperation with Dr. Jürgen Laudien (AWI) we participated in a longterm colonization study with artificial sediments at 20 meters depth.

Polar meiofauna communities show extremely long recovery times after disturbance. That is important for newly ice-free areas and for sites affected by iceberg scouring. Our experiment showed that although the same individual densities were reached after only one year of recovery even after three years the community was characterised by higher copepod numbers than the surroundig sediment (Veit-Köhler et al. 2008).

The German-Argentinian Dallmann Laboratory, an annex to the Argentinian Jubany Station at King George Island, South Shetland Islands, is the starting point for many scientific activities in and around Potter Cove. Since 1994 several depth transects have been sampled in this shallow water area. We study the diversity of harpacticoids and the ecology of meiofauna in relation to sediment structure.

Even when the bay is frozen scuba diving is possible in order to obtain sediment samples. For diving in the Antarctic a scientific diver licence is necessary.

The copepod “giants” of the bay are Pseudotachidius jubanyensis Veit-Köhler & Willen, 1999 and Scottopsyllus praecipuus Veit-Köhler, 2000. Both live at the sea floor and have a body size of one millimeter. In the plankton one of the biggest harpacticoids is Alteutha potter Veit-Köhler & Fuentes, 2007 with 1.7 mm length.

Meiofauna organisms rapidly react to a changing environment. The small animals that belong to the meiofauna are between 32µm and 1 mm in size. They live in the interstitial (between the sand grains) and in muddy sediments on the sea floor. 

Meiofauna reacts very sensitively to grain size or the oxygen concentration in the sediment, to the occurrence and abundance of competitors for food or the negative influence of freshwater. These and other factors directly influence the community structure and species composition of the meiofauna.
With several experimental approaches and expeditions we investigate these relationships.

In ongoing projects we investigate the meiofauna in the intertidal zone of the island of Sylt. We cooperate with colleagues from the Wadden Sea station of the Alfred-Wegener- Institute for Polar and Marine Research in List.
Together with Dr. Nils Volkenborn we tested the reaction of meiofauna on the presence or absence of the lugworm which is known to be a “bioengineer” (Kuhnert et al. 2010). With Dr. Christian Buschbaum we investigate the influence of the invasive Pacific Oyster on the meiofauna.

In the EU-Network of Excellence MarBEF we participated in the meiofaua project MANUELA (Meiobenthic and Nematode biodiversity – Unravelling Ecological and Latitudinal Aspects). During a pan-European experiment we investigated the influence of enhanced rain fall on the meiofauna of beaches.

Paramesochridae

The members of the meiobenthic harpacticoid family Paramesochridae are extremely small crustaceans (Copepoda, Harpacticoida; 0.2 – 0.9 mm). These interstitial animals are cylindrical in shape and are mostly reported from sandy beach ground water, the intertidal and shallow waters. Although some descriptions of deep-sea Paramesochridae exist the genus Kliopsyllus seemed to be restricted to shallow areas. During the deep-sea expeditions carried out under the umbrella of the international Census of the Diversity of Abyssal Marine Life CeDAMar new species of the genus Kliopsyllus were found in 5000 m water depth. This fact is even more astonishing as they form the majority of all Paramesochrid species at the sampled sites.

The species of deep-sea Paramesochridae are rare but extremely widely distributed. Three of the Kliopsyllus-species described by us – Kliopyllus andeep Veit-Köhler, 2004, Kliopsyllus diva Veit-Köhler, 2005 and Kliopsyllus schminkei Veit-Köhler & Drewes, 2009 (from left to right, scale bar 100 µm) – are found in the West-African abyssal plains of the Guinea Basin, the Angola Basin and the Cape Basin (right map). Two species were additionally reported from the Weddell-Sea (left map).

A recent study showed that some of the species of deep-sea Paramesochridae may be cosmopolitan (Gheerardyn und Veit-Köhler 2009).