REMOTE SENSING OF WATER QUALITY IN OPTICALLY COMPLEX LAKES

Solving of several global and regional problems requires adequate data about lake water quality parameters like the amount and type of phytoplankton dominating in the lakes, the amount of dissolved and coloured dissolved organic matter and/or concentration of suspended sediment. Remote sensing is the only practical way to study many lakes provided it can produce sufficiently accurate estimates of the water characteristics. We studied optically very variable lakes in order to test both physics based methods and conventional band-ratio type algorithms in retrieval of water parameters. The modelled spectral library used in the physics based approach provided very good results for chlorophyll-a retrieval. The number of different concentrations of CDOM and suspended matter used in the simulations was too low to provide good estimates of these parameters. Extending the spectral library is currently in progress. Band-ratio type algorithms worked well in chlorophyll-a and CDOM retrieval. None of the algorithms tested for total suspended matter, organic suspended matter and inorganic suspended matter retrieval performed well enough and there is need in further testing

Remote Sensing of Kelp (Laminariales, Ochrophyta): Monitoring Tools and Implications for Wild Harvesting

Kelps (Laminariales, Ochrophyta) are ecologically and commercially important habitat-forming brown macroalgae, found in coastal ecosystems worldwide. Their presence in the sublittoral fringe makes monitoring kelp forests problematic and consequently they remain relatively understudied. Remote sensing offers new avenues to monitor difficult-to-access biomes, particularly kelp habitats, but previous monitoring efforts have only been tested on an ad hoc basis and a standardized protocol for monitoring kelp requires development. In view of on-going and emerging threats to kelp, there is a need for monitoring to establish detailed baseline information. Wild harvesting of kelp is increasing, illustrated by growing numbers of seaweed and seaweed-containing products. Simultaneously, climate change is causing sea-surface temperatures to rise and influencing kelp distribution and abundance globally. This study reviews the potential for remote sensing in macroalgal studies, with an emphasis on kelp and provides a conceptual framework to support the development of standardized monitoring protocols. Satellite-born sensors and aerial photography have been effective, but these distant sensors cannot operate effectively in turbid temperate waters, and many image surveys do not account for changing tides. Advances are being made in acoustic monitoring, particularly multibeam sound navigation and ranging (SONAR). With some development, there is great potential for a standardized monitoring protocol for kelp, aiding management and conservation efforts