Search

In this study, we focused on relatively inexpensive and commonly used fishermen class sonar in order to test its ability to detect stands of charophytes and other groups of submerged angiosperms in the shallow and turbid waters of the Curonian Lagoon. Based on the length of macrophytes, height thresholds (20 and 30 cm) were established in order to distinguish charophytes from submerged angiosperms in obtained echograms. The echograms were visually analysed by two experts. We successfully discriminated 3 echofeatures (bare bottom, stands of charophytes and submerged angiosperms), whereas angiosperms from different morphology groups could not be distinguished. Below 1 m depth, the stands of charophytes and submerged angiosperms were clearly distinguished, thus their maximum colonization depth could be delineated. The accuracy of the discrimination could be reduced by free-drifting mats of filamentous algae, resulting in the overestimation of charophytes. Our approach can be useful for the mapping of monospecific stands of submerged vegetation and could be an important additional tool for macrophyte monitoring and water quality assessment in shallow and turbid waterbodies.

Biological valorisation offers a biocentric approach for intrinsic valuation of the biodiversity of habitats. This conceptual approach was recently applied in few regional studies within Europe using modern statistical approaches. In this study we aim to test the biological valorisation approach that integrates functional diversity of species, species richness, spatial distinctiveness and the status of the communities. Biological value of communities was predicted using Random forest regression method and several environmental factors, such as sediment types, Secchi depth, minimum near-bottom oxygen concentration, near-bottom current velocity, wave generated orbital near-bottom velocity, topographic features. The assessment showed that most valuable habitats are stony bottom reefs with perennial red algae Furcellaria lumbricalis. The obtained map of biological valuation can provide useful information for ecosystem-based management in the studied area indicating conflict zones and protection areas; it could also be adjusted to sensitivity assessment of benthic habitats.

Environmental decision support systems (EDSS) are usually based on environmental models, databases and assessment tools. However, EDSS requires lots of reliable data, which are not readily available, especially information on the distribution of species in marine environments and their dependencies on natural or human pressures. In these cases information is distributed among nominal categories (ranks) which are later used for the decision support. Rules used for assignment into the ranks usually are rough; some of them could be overlapping. But during the decision process the exact rank values are used ignoring the fact that they are derived from the incomplete knowledge. That complicates the comparison of results provided by different cases. In this study a fuzzy logic approach for merging rank and quantitative data with respect to initial accuracy is presented using the example of sensitivity assessment methodology provided by Marine Life Information Network. The proposed approach combines expert knowledge and fuzzy logic methods and provides a possibility to use numerical scales in marine environmental decision support systems, and is a flexible tool for explicit (numerically expressed) sensitivity assessment. This approach can be also applied to other environmental indicators and assessments.

This study presents a quantitative approach to mapping benthophagous fish feeding grounds. This approach combines the spatial biomass distribution of benthic prey items and their importance for the diets of predators. A point based biomass data of macrozoobenthos together with a set of environmental factors was used to develop Random Forests models that produce continuous biomass distribution layers for individual prey species. Depending on the diet composition and the importance of prey for fish feeding, these layers are overlaid and an integrated GIS map of the seabed showing the quality of feeding grounds is generated. These maps provide a useful basis for conservation and marine spatial planning. In addition, this method could be applied to the mapping of resources used by other benthophagous organisms. The method is presented using the example of three common Baltic fish species: cod, flounder and viviparous eelpout.