ABSTRACT
Environmental studies on coastal dune systems are faced with a considerable cost barrier due to the cost of the instrumentation and sensory equipment required for data collection. These systems play an important role in coastal areas as a protection against erosion and as providers of stability to coastal sedimentary deposits. The DIY (Do-It-Yourself) approach to data acquisition can reduce the cost of these environmental studies. In this paper, a low-cost DIY wireless wind data acquisition system is presented which reduces the cost barrier inherent to these types of studies. The system is deployed for the analysis of the foredune of Maspalomas, an arid dune field situated on the south coast of Gran Canaria (Canary Islands, Spain), for the specific purpose of studying the dynamics of a dune type (tongue dunes), which is typical of this environment. The results obtained can be of interest for the study of these coastal environments at both the local level, for the management of this particular dune field, and at the general level for other similar dune fields around the world.
ABSTRACT
This study aimed to add light-avoidance as a categorizing technique for the study of mesopelagic acoustic layers. Data recorded along the 20° W parallel from 20° N to Iceland showed three types of mesopelagic layers: the non-avoiding non-migrant deep scattering layer (NMDSL), which dropped its intensity toward the north, the avoiding migrating fish layers (MDSL), which were more intense at upwelling areas and toward the north, and a secondary deeper NMDSL at the southern part. Light avoidance was only discernible at 18 kHz within the main NMDSL when this layer was intense, suggesting that migrants are barely seen at 38 kHz when other resonant scatterers occupy these depths. These results highlight the importance of employing the 18 kHz frequency from a vessel borne echosounder or lowered echosounders attached to a probe to study gas-bearing migrants.
