|Spatial and temporal variability in settlement of larval plaice along the Dutch, German and Danish Wadden Sea coast|
Zaat, D.S.C. (2017). Spatial and temporal variability in settlement of larval plaice along the Dutch, German and Danish Wadden Sea coast. BA Thesis. NIOZ Royal Institute for Sea Research: Texel. 13 pp.
The goal of this study was to check for possible differences in the size-frequency distribution of larval plaice (Pleuronectes platessa L.) along the nursery areas in the international Wadden Sea. The otoliths of the plaice are the basis of this research. By counting daily rings, different calculations can be made. These calculations would indicate differences in the individual plaice of the different spawning grounds. There has been noticed that there are spatial and temporal differences. There is a major variability in the days of settlement in the nursery areas. This variability indicates the influence of the different spawning grounds offshore in the North Sea. The expected settlement pattern, from west to east has also been noticed In this study, there has been discovered that there is a typical wave pattern in both the frequency of plaice individuals as well as the settling days across the sample stations in the international Wadden Sea. This typical wave pattern can be explained by various factors like temperature, the distance between the spawning ground and the nursery areas and hydrodynamic factors. In this study, we payed attention if there were any differences in larval plaice arrival and contribution from different spawning grounds in the North Sea between a period after a relatively cold winter and a period after a relatively warm winter. This has been done for three different years: 2007, 2008 and 2010. The spawning of plaice usually happens between January and March. This study points out that the larval plaice arrived earlier after a warm period in 2007 and 2008 in comparison with a period after a cold winter in 2010. It was expected that a low temperature period played a significant role in the growth rate of plaice. If this cold period growth dependency holds true it would be is difficult to determine after this study because there are some deviations in the results. Furthermore it was expected that it would take a longer time to transport the larval plaice from the spawning grounds to the nursery areas in the year 2010