Study of strandings of the jellyfish Pelagia noctiluca in the Mediterranean coastline of Tetouan (NW of the Morocco)

Trabajo presentado en el 2nd Scientific Workshop PERSEUS, celebrado en Marrakesh del 2 al 4 de diciembre de 2014.

For a decade, we noticed outbreaks of jellyfish strandings in the coastline of Tetouan especially during heat waves. To examine factors that may be responsible for the stranding of the jellyfish Pelagia noctiluca (Forsskål, 1775) in the coastline of Tetouan (occidental Mediterranean part of Morocco), a monthly monitoring was done at 2 sites (M'diq and Martil) in the years 2011 and 2012. In this study the appearance of these organisms is studied in relation with the tidal currents, wind currents (East wind), weather conditions of the area and physic-chemical parameters of seawater. The appearance of this jellyfish began in June (22.1° C) and reached the maximum of abundance or density in September (24.7° C) to disappear in October. This density fluctuation is correlated with changes in ambient temperature. Analysis of the structure of the population size (umbrella diameter) of the jellyfish shows a size range between 10 mm and 90 mm and an average of 49 mm. Other studies have also observed that the outbreak of the Medusa seems to be related to warm temperatures. Nevertheless, the different processes that are involved in the appearance of jellyfish in a specific coastal area operate at diverse time and spatial scales, which demand to take into account an wide perspective in order to analyze their population dynamics.

No