Invasive zebra mussel – is it a problem?

Hovedområde:Aquatic biology
Niveau:Bachelor, Masters
The zebra mussel (Dreissena polymorpha) is well establishing in numerous Danish lakes and is currently spreading to more sites via major rivers and most like also by humans. At present we have only have reports of their density and biomass from a relatively small number of localities. Given the many routes of transmission open to the zebra mussels (e.g. streams, birds, anglers) it is a reasonable assumption that they are frequently occurring in Danish watercourses. Zebra mussels can filter large quantities of water in a short amount of time and will therefore likely affect the amount and composition of the plankton. There are many opportunities to construct a bachelor project within this topic – here are just a few suggestions for you to get inspired. Project subject 1: Mapping of the current presence, description of invasion history of zebra mussel and an overview of their effects on other biota based on scientific papers, reports, newspaper articles, www-sources and other media. It can easily be combined with field survey of locations where presence is of the mussel is not conformed or not previously reported. On top, it would be highly relevant to outline of the potential management tools (e.g. based on published material and on interviews with the relevant authorities). The whole project combined will be of interest for researchers, naturalist as well local and national environmental mangers. Project subject 2: Screening of occurrence and density of zebra mussels in specific lakes based on existing literature and on field sampling. Field work will be by means of sampling in the littoral zone, by snorkelling and dredging at deeper parts. Measurements of sediment conditions and water quality will be included as well. Possible sites to be studied: a) Arresø (the largest lake in DK), where the mussel was discovered for the first time in 2016 b) Small lakes and streams that are connected to Arresø to see, if the mussel has spread c) Esrum sø and Furesø, where the mussel has been well established since many years d) Frederiksborg Slotssø, where a population has established over the last 20-30 years but seems to fluctuated between years Project subject 3: Comparison of zebra mussel propagation patterns in Denmark and other countries (e.g. USA, Europe, Scandinavia) based on the literature- and species databases in combination with a discussion of the optimal physical and chemical conditions for the establishment of a zebra mussel population (based on the literature and/or own experiments). Project subject 4: Investigations of the importance of basic environmental conditions such as light, temperature, oxygen and food for zebra mussel growth and survival to better understand why they thrive in some places and not in others. This can be carried out field and laboratory experiments – or ideally as
Anvendte metoder:Field sampling, snorkling, scrabe sediments, basic water chemistry, microscopy, lab experiments
Keywords:Invasive species, Zebra mussel, Lake ecology, Food webs
Vejleder(e): Kirsten S. Christoffersen