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Focus areas

 Major focus areas for our research


1) A Baseline study of the population biology of C. maenas.

C. maenasis an important marine biological model species in many marine biological contexts, but despite this there is an astonishing lack of knowledge about its population biology. Even basic parameters such as growth rate, age distribution, life etc. is not or only poorly known. A multi-year baseline study of the species' original environment can quantitatively and qualitatively form the basis of similar studies conducted in the invaded areas. The present project, therefore, focus particularly on how abiotic key parameters such as salinity, currents, water depths and temperatures influences parasite prevalence, crab size and distribution in the Limfjord.


2) Importance of parasites.

We are conducting a general parasitological study of the parasitic fauna of C. maenas in the study area. Special emphasis will be placed on the parasitic barnacle, Sacculina carcini, which is the predominant Carcinus parasite of the area and the most obvious candidate for a potential biological control agent of the host population. A detailed mapping of the spread of the parasites in the fjord will provide important information on host-parasite dynamics. However, screening of the general parasite fauna with classical parasitological investigations is extremely labor-intensive, so the parasitological work will be conducted using a newly developed molecular dHPLC protocol, which is both faster and safer than the traditional manual method of parasite monitoring. Furthermore, the influence of the parasite fauna on the physiological conditions of C. maenas will be investigated via an array of immunological methods.


3) The castrating parasite, Sacculina carcini

We are studying Host-parasite interactions by mapping C. maenas and the parasite fauna at representative sites in the fjord. Prevalence of S. carcini, and possibly other parasites varies extremely widely between different locations in the Limfjord (~ 0 - 50%). We will try to clarify whether the local crab parasite free refuge. This will be compared with studies of the parasite-free crab in the U.S. and Australia in collaboration with our associates in these areas.

The study of S. carcini will include its horizontal and vertical distribution in the study area. Such data, both for the Danish waters and elsewhere in the host's "home range", is very few in number and the population dynamic part of the biology of S. carcini is poorly understood (especially larval production, dispersal and larval ecological tolerances is practically unknown).


4) The study site and population dynamic of host and parasites

Limfjorden is an ideal area for field-testing a marine parasites adequacy for stock regulating its host. In Limfjorden C. maenas demonstrates its unique physiological ability to live and reproduce in highly variable conditions. Furthermore, the authorities, through more than a hundred years, have intensively monitored this area, why there exist fully accessible and detailed biotic and abiotic data for the entire period, and there are few equally studied and hydrological well-understood systems anywhere in the world. The prevalence of S. carcini and other parasites varies dramatically from locality to locality in the fjord. Within a few kilometers distance the prevalence of a certain parasite species can go from 0 to 100%. The Limfjord is furthermore almost an isolated water system entailing that both the host and parasites are part of a closed genetic system with no or very little exchange with other populations outside the area. Limfjorden is, therefore, well-suited study area for a study investigating the mechanisms influencing the population dynamic of the host and its parasites.  

For the purpose of these studies microsatellites has been developed for S. carcini.