Carcinus meanas: wereldveroveraar. Wereldwijde invasies vastgelegd door middel van populatie genetica

 

Data acquired with the SETL-project, i.e. 160 fouling plates which are analysed and replaced every three months over the last three years, is stored in a database. Questions like: “Do species have a preference for the location on the pvc-plate they settle on?”, or “Do species attract or reject other species?” could easily be answered with data from this database. Analyses like these would require a lot of time and patience, if done manually though. That is why I am going to make a computer program in which one can select the location(s), species, and the type of analysis one wants to do on the selected data. The program will then give the results, leaving you with exactly what you need to make your conclusions.

 

The SETL-project determines marine biodiversity by identifying species which settle on pvc-plates. This is done for every season. However, marine communities on these plates could be very different depending on when plates are submersed and on the length of submersion. Succession may play an important role in species assemblage in which early colonizers have an influence (stimulation or inhibition) on later colonizers. My research will focus on the question whether succession occurs among marine fouling communities and whether the time of submersion of the SETL-plates determines the eventual (climax) community.

 

Floating artificial structures (or FAS), like pontoons and buoys, form a relatively new and unnatural habitat. FAS have a unique combination of characteristics that makes it hard to predict which species will occur on it. In this study I will try to find out what species or groups of species have their living on FAS, using the SETL-plates as well as floating docks. So, a description of FAS, both abiotic and biotic, will be made. Eventually, it is interesting to see how FAS represent the Dutch marine fauna.

In recent years marine invasive species, i.e. species that are introduced in an area outside of their native distribution, have had an increased impact worldwide. This is at least partly due to global warming and partly due to intensified boat traffic. They can e.g. threaten public health, be a great nuisance for tourists, and cause substantial economical damage to marine systems and related industry. The rapid detection of a new species being tranported into Dutch waters in e.g. the ballastwater of boats coming from the American coast, can be of great help to reduce the chance of these species settling and becoming harmfull to our ecosystem and economy. For the rapid detection of marine invasive species, rapid species identification techniques are of the uttermost importance. Identifying organisms in their early life stages, e.g. in their larval stages in the ballastwater of a boat, on the basis of morphology can be a difficult to impossible task. DNA-barcoding as an identification technique is therefore becoming more and more popular. By sequencing the DNA of an organism and by comparing the resulting sequence with the known DNA-barcodes of a range of species, one can easily identify any organism. A disadvantage of the method is that one can only identify species of which the DNA has already been sequenced in the past. For that purpose GiMaRIS has joined forces with the TOPlab of the Leiden University of Applied Sciences. Marine species, both natives and non-natives, are identified on the basis on their morphology in the GiMaRIS lab after which they are sequenced in the TOPlab, with the well appreciated help of students like Shelly.

 

Invasive alien species pose a growing thread to nature and society. It is said that only some alien species possess trades that allow them to become invasive. They can spread very fast, can adapt to a large variety of environments and are serious competition to native species. To study these trades I have focused on the settlement behavior of the sea-squirts Botryllus schlosseri and Botrylloides violaceus. These are two similar species, which are very successful invaders in America. In Dutch waters however B. schlosseri is native whereas B. violaceus is an alien species. Questioning whether species show their invasive trades only in their non-native area, we are comparing the behavior of these two species along the Atlantic coasts of NW Europe and NE America.

 

To study fouling communities along the Dutch coasts, 14 x 14 cm, PVC plates are being deployed at a depth of 1 meter, checked for species and replaced by new plates every three months since 2006: the SETL-project. The plates are digitally subdivided in 25 equal grids (figure 1), and every species per grid is scored after which this data is stored in a database. Over the years the SETL database has grown exponentially, containing over 625000 presence/absence records for fouling species over the period 2009 to 2010. Here we present SETLyze, an application that is capable of performing a set of analyses on data from the SETL
database.