The aim of this paper is to present an analytical study of gonad index (GI) and repletion index (RI) of Holothuria (Holothuria) tubulosa Gmelin, 1791 (Echinodermata Holothuroidea Holothuriidae). The study is based on biomonitoring data collected from February 2014 to January 2015 in the Oran coast. The gonad index of Holothuria tubulosa is analyzed to show the reproductive cycle and its relationship to environmental parameter conditions. Samples of 15 to 20 individuals were collected monthly at three stations on the Oran coast (La Madrague, Cap Carbon, and Ain Franin). The sex ratio of all sampling was found as (female: male) 0.8:1.2 with no significant difference between sites (X 2 = 2.18 ; df=4 ; p>0.05) and is also not significant regarding the seasons (spring, summer, autumn, winter) (X2= 3.03 ; df=6 ; p>0.05). Sea cucumber reproduction occurred in September at Cap Carbon and Ain Franin with values of Gonad index (GI) that are 0.33± 0.52 % and 0.22± 0.52 % respectively. At the La Madrague site, the spawning occurred in October with a value of GI of 1.49±2.03 %. It was observed that seawater temperature has a positive correlation with Gonad index (GI) and no correlation with Repletion index (RI).

The objective of this study is the evaluation of the resistance of the bioindicative species Patella rustica Linnaeus, 1758 (Gastropoda Patellidae) existing in the contrasted sites of the Algerian occidental seaboard through a follow-up of the seasonal variations of biometric indices. It is based on the analysis of biometric parameters of 600 individuals of this Gastropod mollusk from five sites: Madagh (MD), Bouzedjar Harbor (BH), Ain El Turck (AT), Oran Harbor (OH), and Kristel (KR). The seasonal sampling has been carried out and measurements on the height of the shell (H), its length (L), and its total weight (TW) are taken for all the populations of P. rustica. The correlation of the different measurements (length-height, length-total weight, height-total weight), with the help of the power curve and following STUDENT " t " test, DUNCAN, and the ACP, reveals the development of its shell first in height, followed in second position by the length, and this for the five sites under study. Weight would thus be the parameter under analysis that evolves the least quickly as compared to the other two biometric parameters involving a generally significant difference between the five sites under study. These results confirm that the growth of this mollusk varies depending on the seasons and relies on many biotic and abiotic factors that also condition the development of the shell and the growth of limpet. This approach represents a good means for environmental evaluation that could be used in biomonitoring programs to indicate the impact of pollution in the short and long term.

This study assesses the characteristics of the metallic trace elements (Fe, Cd, Cu, Pb and Zn) in the Paracentrotus lividus gonads. The physiological indices evolution (RIm and GIm) was adopted in order to determine the laying period of this echinoid; and to support the hypothesis that this species may be considered as an excellent bioindicator in the marine environment. For this purpose, two edible sea urchin populations with a diameter between 41 and 71 mm were sampled. This samples were taken from two different sites, Salamandre area (presence of rocky seabed rich of photophilic algae, with less biodiversity), and Sidi Lakhdarin area (presence photophilic algae and Posidonia oceanica, more biodiversity). Each sample was evaluated by the coupled plasma mass spectrometry (ICP-MS) method. The results obtained show that there is a significant variation (p<0.005) of physiological indices (RIm and GIm) over time. Besides, an important spawning increase is observed during spring and autumn. The results revealed that gonads metallic contaminations were present in all samples, with very heterogeneous concentrations. Also, it demonstrates that the metallic contamination existed in all seasons, with a clear demarcation of zinc and iron. The zinc quantity is 2.159 mg/l in Sidi Lakhdar and 1.413 mg/l in Salamandre; and the iron quantity is 2.088 mg/l in Sidi Lakhdar and 1.888 mg/l in Salamandre. Unlike zinc and iron, copper and cadmium have small amounts in the two sites. In the autumn, the cadmium quantity is 0.005 mg/l in the two sites; and the copper quantity is 0.068 mg/l in Sidi Lakhdar and 0.065 mg/l in Salamandre. Consequently, this marine species accumulates large quantities of these toxic metals according to the bioavailability of the pollutant in the surrounding environment.

Seasonal variation in the physiological indices and biochemical composition of the sea urchin Paracentrotus lividus (Lamarck, 1816) (Echinodermata Echinoidea) from the west coast of Algeria were studied between March 2016 and February 2017 from three stations of different nature and geographical position: Sidi Lakhdar (S1), Cap Carbon (S2), and Benisaf harbor (S3). Two spawning period occurred in spring and autumn, resulting in a fall in gonad indices to a low level with values between 2.14 and 3.65%. The seawater temperature in the three sampling stations revealed that the latter had a spawning rate at 9-15 °C in spring and 24 and 11 °C in autumn corresponding to the two peaks of spawning. The biochemical composition of the gonads protein contents, carbohydrates and lipids were recorded with a high percentage for proteins between (25.80 and 45.23%) followed by that of lipids (9.21 and 14.40%) and finally carbohydrates (3.49 and 7.39%). In accordance with the gonad cycle, sea urchin lipids and proteins show a marked seasonal variation with a decrease in their percentages during the spawning period. Protein levels had an inverse profile with carbohydrates, with their values at a minimum when carbohydrates were at their maximum. The profile of the total components in the gut content is almost the same as in the gonads with minus values. A relationship has been found between the biochemical components of the gonads and the digestive tract during gametogenesis, the latter seems to be an organ that tends to store nutrients, indicating that populations of sea urchin P. lividus are in good nutritional conditions.