The impact of waves on the distribution of submerged macrophytes in kalvöfjord, sweden – a study of “comfort zones” / Vindvågors betydelse för distributionen av makrofyter i kalvöfjorden, – en studie av »komfortzoner»
A study of a shallow bay (Kalvöfjord) on the west coast of Sweden was conducted to determine the potential for wind waves to control the distribution of submerged macrophytes. A wave model was implemented, calculating the drag force exerted by the wave orbital motion. A new concept of “comfort zones” was introduced, ascribing an interval of survival to a certain species under the influence of a certain physical variable. A brief study of drought risk was also included. The model results showed that the Kalvöfjord most often is subject to low stresses, but with occasional intensifications associated with significant drag upon macrophytes. The observed zonation in the bay largely coincided with the different levels of stress, where Zostera marina was confined to parts with the lowest stresses, and without risk of drought (depth ≥ 1.2 m), whereas the fucoid algae were found exclusively in areas of moderate stress, although not shallower than circa 0.5 m. The locations of fucoid algae suggested that they inhabit an interval of drag stress, which is consistent with their requirement of some water movement to receive nutrients – at the same time having a structure vulnerable to drag. Ruppia maritima was found to be very resilient to both drag and drought, occurring sporadically at depths as shallow as 0.2 m.