The Paracentrotus lividus populations from the northern Moroccan Atlantic coast: growth, reproduction and health condition

Abstract

The condition of three intertidal Paracentrotus lividus populations, which inhabit an area between Rabat and Casablanca (Morocco) known by its high wave energy and its substantial anthropogenic disturbances were described. The growth rate of the juvenile sea urchins in this intertidal zone was low compared with more sheltered populations. A sharp increase in the gonad index was observed between January and March at the beginning of a period of algal production, and was concomitant with increases in seawater temperature and food consumption rate. This gonad index increase was followed by a single spawning period occurring between March and June, probably triggered by the phytoplankton bloom induced by upwelling conditions. Larval development in all three populations was severely inhibited and could be explained, in part, by high and generalized Cu contamination throughout the region. Specific contamination of particular populations by Pb or Hg was attributed to local industries and the incomplete dispersion of pollutants in spite of the high hydrodynamics along the Moroccan Atlantic coast. One of the three populations studied showed strong indications of abnormal development; the degradation of its condition appeared to be due to the presence of a wadi (temporary river) which can seasonally reduce the salinity, directly affecting the sea urchin physiology and indirectly enhancing the metal toxicity.

Functional traits of two co-occurring sea urchins across a barren/forest patch system

“…Accordingly, gut content analysis indicates a strong feeding preference for encrusting corallines by A. lixula, in contrast with fleshy algae by P. lividus (Privitera et al, 2008 and reference therein). Moreover, some demonstrated larger lantern size (which indicates an increasing ability to scrape) and lower gonad somatic index values (a stress response, impairing fitness) in sea urchins inhabiting food-limited habitats, such as the barren, relative to those inhabiting habitats with abundant food, such as forest algae (Agatsuma et al, 2005;Bayed et al, 2005;Brady and Scheibling, 2006;Brewin et al, 2000;Byrne, 1990;Fernandez and Boudouresque, 1997;Konar and Estes, 2003;Levitan, 1992;Sànchez-España et al, 2004).…”

Relationships between algal food and gut and gonad conditions in the Mediterranean sea urchin Paracentrotus lividus (Lam.)

“…Considering the relationship with the availability of algal resources, we can compare the annual evolution of GI and RI. Bayed et al (2005), in their study on Atlantic populations of Morocco, indicate that the RI (dry weight) varies significantly over time, with annual peaks being recorded just before (February) and during the spawning period (April), although decreasing in March, when the GI is at its maximum value. In our population, the RI is highest in spring and early summer, especially for large individuals, corresponding to increased feeding activity and greater dedication of resources to reproduction.…”

“…According to these authors, the variations observed from one locality to another in the time the GI reaches its annual maximum, are related more or less directly with the availability of food as indicated by Lawrence & Lane (1982). Differences in GI between locations are often observed (González-Irusta et al, 2010) and are also related to other factors such as farm effluents and organic pollution (Allain, 1975;Delmas & Régis, 1986;Cook & Kelly, 2007), temperature (Byrne, 1990), phytoplankton blooms (Lozano et al, 1995;Bayed et al, 2005) and salinity and contamination by heavy metals (Bayed et al, 2005). Considering the relationship with the availability of algal resources, we can compare the annual evolution of GI and RI.…”

“…Furthermore, this author concluded the gonad growth occurs during the coldest part of the year, coinciding with months with shorter days -both temperature and daylight being parameters that determine the gonad growth during winter -, and that the photoperiod does not affect the release of gametes. Bayed et al (2005) detected that on the northern Atlantic coast of Morocco the increase in gonad index occurs between January and March, coinciding with the beginning of a period of algal production, concurrent with increases in water temperature and rates of food consumption. This increase in gonad index is followed by a single spawning period between March and June, possibly triggered by the phytoplankton bloom in the area.…”

“…It seems that habitat characteristics (Byrne, 1990), hydrodynamic conditions (Sellem & Guillou, 2007), seawater temperature (Byrne, 1990;Bayed et al, 2005;González-Irusta et al, 2010), algal production (Bayed et al, 2005), food availability (Guidetti et al, 2003;Sánchez-España et al, 2004), phytoplankton bloom (Lozano et al, 1995;Bayed et al, 2005;González-Irusta et al, 2010) and photoperiod (González-Irusta et al, 2010) are of particular importance.…”