Evaluation des traits de vie d'une espèce endémique du Maroc (<em>Salmo trutta macrostigma</em>, Dumeril, 1858) dans une rivière du Moyen Atlas du Maroc: Oued Sidi Rachid

Abstract

RESUME Cette étude a pour objectif la contribution à la détermination de la qualité physicochimique des eaux de l'Oued Sidi Rachid au Moyen Atlas où vit une espèce endémique du Maroc : la truite de rivière (Salmo trutta macrostigma, Duméril, 1858). L'étude des paramètres essentiels pour la vie de ce salmonidé au cours de la période comprise entre le mois de mai 2007 et le mois d'avril 2008 montre que la température, le potentiel Hydrogène (pH) et les concentrations des nitrites témoignent de la bonne qualité des eaux de l'Oued Sidi Rachid et permettent de classer ce site parmi les sites à vocation salmonicole. Les concentrations des orthophosphates sont très faibles et ne témoignent d'aucune source de pollution organique. Les concentrations des indicateurs de la dureté reflètent la nature géologique (carbonatée) de la région. Les résultats obtenus montrent bien que les eaux de l'Oued Sidi Rachid assurent à la truite de rivière un bon habitat écologique favorable à son développement et à sa reproduction.

Assessment of heavy metal and organic pollution of a salmonid ecosystem: Case of the Oued Guigou River, Middle Atlas (Morocco)

“…The water acidity is acceptable for survival of the Salmo trutta species (Abba et al, 2012). Regarding the electrical conductivity of the water of Oued Guigou waters, the average value is 329.7 μS/cm, consistent with the conductivity of natural waters that oscillate between 50 and 1500 μS/cm.…”

“…Calcium and magnesium are found in all natural waters, with calcium contributing significantly to their hardness (Abba et al, 2012). The copper (Cu 2+ ) concentrations observed in the study area (Table 3) indicate a high contamination level in the Oued Guigou waters, with average and maximum concentrations of 0.03 mg/L and 0.039 mg/L respectively, both exceeding the 2 μg/L Moroccan standard.…”

“…These concentrations are attributed to the retention of these ions in soil particles subsequently mobilized by the existing vegetation, and which can slow the rate of brown trout migration in the water (Matetski et al, 2022). Calcium and magnesium are found in all natural waters, with calcium contributing significantly to their hardness (Abba et al, 2012). The copper (Cu 2+ ) concentrations observed in the study area (Table 3) indicate a high contamination level in the Oued Guigou waters, with average and maximum concentrations of 0.03 mg/L and 0.039 mg/L respectively, both exceeding the 2 μg/L Moroccan standard.…”

“…In addition to the presence of landscaping works on the borders of Oued Guigou, these works generate disturbances in the ecology of aquatic systems by increasing the average TSS and turbidity levels in the water, causing a clogging of spawning grounds and asphyxia due to a lack of oxygen (Bud et al, 2009). The water temperature is an important ecological factor in the aquatic environment, affecting both the biology and behaviour of the trout (Abba et al, 2012) by regulating almost all physical, chemical, and biological reactions. In the study area, and during the study period, an average temperature of 9.93°C was noted.…”

“…As the evolution of fish populations is directly related to natural and artificial variations in their habitats, including water quality, these pollutants can affect the biology of the fish populations in aquatic environments. The physical and chemical parameters in the water resources also can interact either synergistically or antagonistically, further complicating the situation (Abba et al, 2012).…”