Assessment of Moroccan coastal fish habitat and water quality
Together with Moroccan partners we investigate the pollution of fishes from Moroccan coastal waters.
The Atlantic coast of Morocco is one of the richest fishing grounds in the world. Altogether, Morocco's coast line covers 2,141 miles along the Mediterranean Sea and Atlantic Ocean. Fishing has been a major industry in Morocco since the 1930's and the industry experienced tremendous growth during the 1980's. However, together with waste management and desertification, water quality and coastal pollution are considered the two major environmental issues. Estuarine and nearshore living benthic and demersal fish species are among the most vulnerable members of the marine food chain in terms of chemical pollution. While pollution of surface water is mostly periodic and linked to specific emission events, contamination in or near sediments remains persistent. Benthic fish species like freshwater eels, congers and moray eels considered stationary during their growth phase, live close to the sediment and are known to accumulate chemical pollutants due to their high position in the food chain and their high lipid content. By analyzing the contamination of European eel (Anguilla anguilla), European conger (Conger conger) as well as Mediterranean moray (Muraena helena) for heavy metals as well as PAH-metabolites (degradation products of fossil oil) at several estuarine sampling stations along the Moroccan Mediterranean and Atlantic coastline we want to determine and map hotspots of coastal pollution and provide a risk assessment of fish consumption in the area. A country-wide study showing different contamination levels in fish is lacking so far.
The overall goal beside the scientific progress is to build a scientific network and support young researchers. Shared knowledge will improve the progress of the master and PhD students involved in this project.
The project aims on determination of PAH metabolites and heavy metals in fish (Eel, Muray, Conger) from Morocco. Therefore sampling is an important task which will be planned jointly before the investigations starts. Sampling areas will be selected in three major regions (number of locations): Atlantic Coast (4), Mediterranian Coast (3), Estuaries (2) and Background (1). In each major region sampling locations will be defined including possible contamination hot spot as well as reference areas with a suspected lower contamination. Due to former studies in other fish species we will use 15 single fish samples to describe the pollution at the different sampling locations. Fish will be bought from local fisherman or from the market. If possible local vessels are included in sampling activities.
In total a maximum of 450 samples will we analyzed for PAH metabolites and heavy metals on an individual level. A master record containing sample identifiers and all the relevant sample properties (location, GPS codes, date, storage, biological parameters of fish etc.) will be prepared provided to each person involved in the analytics. Researchers from Germany and Morocco will meet and work together. Chemical analytics will take part in Thünen Institute and biological sampling as well as aspects of sample preparation will take part at the Mohammed V University Morocco. For this Moroccan students will be trained in Germany and will after that together with support from Thünen scientists evaluate the possibilities for the best use of facilities in Morocco. Researchers from Germany will come to Morocco to perform additional sampling. Researchers from Morocco will come to Germany to establish a scientific bi-national network supported by interdisciplinary aspects concerning biology and analytical chemistry.
In total 12 sites along the mediterranean and atlanctic coastline of Morocco were visited and 182 samples were taken and analysed. Six diferent species were covered: Muraena helena, Conger conger, Halobartrachus didactylus, Anguilla anguilla, Ophidiinae barbatum and Gymnothorax unicolor. Samples were analysed for 1-hydroxy-pyrene in bile, mercury in muscle as well as cadmium an lead in liver tissue.
Regarding the contaminants Anguilla anguilla exhibits highest mean values for 1-hydroxy pyrene an lead. Murena helena has the highest mean values for mercury and cadmium.
Around 50% of the EU food threshold were reached by Muraena helena and Conger conger longer than about 80 cm. Such fish should be consumed less often.
5.2017 - 4.2021
Project funding number: 01DH17005
Project status: ongoing