Náttúra og náttúrutilfeingi
Vatnskiftið í Sundalagnum og grannafirðum: Ein modelkanning.
Knud Simonsen, Lars Asplin
Stuðul úr Granskingargrunninum:
The coast of Sundalagi and adjacent fjords hosts more than half of the faroese population, some of the most busy harbours and a large fraction of the industry in the country. In these fjords a significant part of the faroese export of farmed salmon, in addition to other marine products, is grown out. Detailed understanding of the circulation and the water exchange between the various basins in this fjord system is a prerequisite for skilful spatial management and risk assessments of potential accidental pollution. In the aquaculture unerstanding the dispersion of diseases and parasites, in particular the sea lice, from one site to another is of vital interest.
The primary production in Faroese fjords is generally 2-3- times higher than in other countries at the same lattitude. This is suggested to be linked to the relatively small size of the fjords and the variable weather conditions. One aim of this project is to get a better understanding of the underlying physical processes responsible for the high primary production. The fjord system of Sundalagi and adjacent fjords includes several basins, where stagnant bottom layer may develop during summer, which may cause benthic oxygen depletation. Understanding the hydrography, the acting vertical mixing mechnism and how it may affect the primary production is thus essential in estimating the biological carrying capacity of these basins, which also is of increasing international awarenes in aquaculture management strategies.
In this PhD-project a high resolution numerical 3D-model will be implemented for the Sundalagi and adjacent fjords in order to understand the circulation and water exchange between the different part of the fjords, which has a quite complex bathymetry and variable hydrography. The model simulations will be validated towards a vast amount of data including hydrographic and current profile data both from spatial surveys and timeseries from moored instruments. The influence of various weather conditions on the hydrography and circulation on both short and seasonal scale will be investigated with emphasis on influence on the stratification, the vertical mixing processes, residence time in the various basins and how present fish farms are dynamically connected. Further, a sea lice model will be coupled to the physical model in order to increase the understanding of the spatial, vertical and temporal dispersion of the first stages of sea lice obtained from recent succesful plankton net trawlings in the region