CLIONA VIRIDIS: MINERAL COMPOSITION AND CONTRIBUTION TO THE ASSESSMENT OF THE QUALITY OF THE MARINE ENVIRONMENT

Khadija BARY. The lifestyle and aquiferous system of sponges are the main factors behind their structural characteristics. They are capable of filtering large volumes of water and have a high rate of retention for particles of 0.2 to 50 microns (μm) and therefore a large capacity accumulation of pollutants. At the same time, members of all sponge classes (Demospongea, Sclerospongea, Hyalospongea) can secrete mineral elements called spicules of opaline silica. These siliceous spicules constitute their skeletons involved in several functions, namely in defense, support and the like. Cliona viridis is chosen for the study of mineral composition, and contribution to the evaluation of the quality of the marine environment by measuring the concentration of certain heavy metals in two different zones.


Khadija BARY.
The lifestyle and aquiferous system of sponges are the main factors behind their structural characteristics. They are capable of filtering large volumes of water and have a high rate of retention for particles of 0.2 to 50 microns (µm) and therefore a large capacity accumulation of pollutants. At the same time, members of all sponge classes (Demospongea, Sclerospongea, Hyalospongea) can secrete mineral elements called spicules of opaline silica. These siliceous spicules constitute their skeletons involved in several functions, namely in defense, support and the like. Cliona viridis is chosen for the study of mineral composition, and contribution to the evaluation of the quality of the marine environment by measuring the concentration of certain heavy metals in two different zones.
Silica SiO 2 is 70.99% (± 0.23) of the biomass of the sponge with other minerals such as sodium, chlorine and calcium. The zinc (Zn) is the most accumulated metal then Iron (Fe) and aluminum (Al).
A large study with several species collected from different areas will allow us to understand the process of accumulation of silica and heavy metals and have a good image of level of contamination of the marine environment.

Introduction:-
Most sponges are symbiotic microorganisms that provide a significant amount of dissolved organic material in their diet (Reiswig, 1981) and secrete a variety of calcite mineral skeletons, aragonite and (or) of amorphous silica which reinforce and protect the physical disturbance. However, siliceous spicules are formed from a medium that is undersaturated with silicon. Silicification is the dominant process of biomineralization in the current sponge (92% of species). (Maria J-Uriz, 2006). Their sophisticated aquiferous system gives them the ability to actively filter a water volume equivalent to their own volume in 3.

Results:-
The total ash content:-The percentage by weight of the total ash obtained from the sample and in the dry matter is equal to: CT% = (m2-m 0) / (m1-m0) * 100. With: m0: mass in grams of the empty capsule. ml: mass in grams of the dish and the sample. m2: mass in grams, of the dish and the total ash. The percentage of the total ash Cliona viridis is: % Total ash = 65, 7% (±0. 4) Insoluble ash Hydrochloric acid 10% (C.In/Acide):-Ash insoluble in hydrochloric acid consists mainly of silica and silicates. This residue also called "sand" is likened to the earth and other mineral impurities. The percentage by mass of ash insoluble in acid obtained from the sample in the dry matter, is equal to: % C.In/acid = (m3 -m0) / (m1 -m0) * 100. With: m0: mass in grams of the empty capsule. m1: mass in grams of the empty capsule and the sample. m3: mass in grams of the dish and ash insoluble in acid.
The percentage of ash insoluble in acid obtained Cliona viridis is: C.In/Acide= 54,85%(± 0.2) So the ash insoluble exhibit 36% relative to the dry matter.  b. ICP-OES method: The Metal concentrations (ppm) measured in samples taken from two sites (S1and S2) are shown in the following table (Tab.2) and Figure (Fig.2). The study of heavy metals in Cliona viridis shows that concentrations vary depending on the sampling site. We note that (i) used concentrations in this species, collected in site S2 (Jorf Lasfar Port of trading, which is a basin where the exchange with the ocean is very limited, and which boost the concentration of different polluted discharges) are higher than the concentrations of marine waters reported in the literature (P.W. Ball. 2004), and (ii) these levels are significantly higher compared to those observed in the same species collected at site 1 (El Jadida-Sidi Bouzid's wide, less polluted and open zone).
The analysis revealed a chemical bioaccumulation of several metals: Zn, Fe, Al, Cd in the case of Cliona viridis. It also indicates that these metals are related to the life cycle of these animals and others to marine pollution due to human activities that generate pollutants affecting water quality, threatening marine life and consequently affecting the food chain and human health.

Discussion and conclusion:-
Indeed, the high value of the silica in the case of Cliona viridis can be explained by the fact that this marine sponge belongs to the class of Demospongiae whose backbone, more or less rigid, consists of spicules, siliceous or spongin. Some spicules can be large (megascleres). They are essential to the structure of the animal. Others, smaller (microscleres) are embedded in the parenchyma. They are often organized in the backbone with their pointed end into or projecting from the surface of the sponge.
According to the results, the mineral composition of Cliona Viridis mostly consists of silica (SiO 2 ) with some trace elements. This is consistent with previous studies carried out on Demosponges. This composition varies slightly depending on the species and concentration of the water they contain. Other inorganic irons which do not take part in the spicules composition, such as Fe 2+ , appear to be decisive in activating the enzymes that catalyze silica polymerization (Le Pennec et al., 2003). Also, It is outlined that silicon and Fe 3+ contribute substantially to the formation of larger primmorphs (size of 10 mm) as well as of a canal system in primmorphs; canals are probabl y required for an improved oxygen and food supply. Spicules seem to represent harmful elements in the food, particularly if we consider that they may represent up to 75% of the sponge biomass (Rutzler and Macintyre, 1978; Desqueyroux-Faundez, 1990) and that they are often arranged in the skeleton with their sharp end towards or protruding the sponge surface. As a consequence, the siliceous skeleton of sponges has often been interpreted as an effective mechanism for deterring predation (Randall and Hartman, 1968; Sara`and Vacelet, 1973). Spicule concentration appears to be a plastic trait that can be induced by damage in some morphotypes of Antosigmella varians Duchanssaing and Michelotti (Hill and Hill, 2002). These authors found that sponges unprotected from predators increased spicule yields, and suggest that the large spicule rich cortex of these morphotypes is an inducible structural defense.
Several other functions, sometimes complementary to the main supporting role, can be envisaged for sponge spicules, although most of them appear exclusive of particular species. In extreme environments where an active filter feeder has a low yield, the family Cladorhizidae Dendy has developed particular tools for capturing living prey passively, which consist of long thin tentacles provided with a dense layer of protruding upraised hook-shaped microscleres. These carnivorous sponges capture small crustaceans (less than 1 mm in size), which are entrapped thanks tothe sponge microscleres (Vacelet and Boury-Esnault, 1995).
Spicules also appear to play a role in gamete and larvae dispersal of some species. Certain larval spicules such as the discotriaenes that cover the hoplitomella larva of Alectonidae (Vacelet, 1995) are not present in the adults. Some of the larval spicules notably favor larval buoyancy and thus may increase larval dispersal, as reported for the styles that largely protrude through the armored hoplitomella of Alectonidae, which can be found among the oceanic plankton (Tregouboff, 1942).
Indeed Sponges absorb not only silica but thanks to their aquiferous system, these invertebrates are suspensionfeeders that filter large amounts of water. However, the nature of the organic material and the size of the particles that are retained differ significantly. Sponges have a high retention rate for particles of bacteria size, and appear to be able to meet their entire carbon requirements by feeding on particles smaller than 1 μm (Stuart & Klumpp, 1984; Ribes et al., 1999). In contrast, sponges may live several decades and thus accumulate during a longer time.
The diversity of morphology of the aquiferous system may be related to their ability to up-take a wide array of particles and to their powerful pumping activity influencing the water volumes passing through the body (Reiswig, 1975), and thus the pollutant accumulation.
At the sponge Cliona viridis object of study, the Zinc (Zn) is the most accumulated metal, a result similar to that found by Thierry perez and all. 2004. Also it shows very high concentrations of the Iron (Fe) and the Aluminium (Al). This sponge, which contains a large mineral fraction, made of calcareous debris and of skeletal siliceous spicules, also has a very different mode of life. All clionid sponges (family Clionaidae) excavate calcareous substrates.
The special behavior of C. viridis for accumulation of metals may be related to this ability to bio-erode calcareous substrates, which are frequently biological concretions made primarily by calcareous algae, which are themselves able to accumulate heavy metals mainly from the dissolved fraction. Cliona viridis is unique in its symbiotic association. It is associated with a large quantity of light-dependent zooxanthellae ( The structure and biological composition of the sponge are probably the most important factors for its ability to retain or to eliminate the metals. The skeletal structure, whose size varies considerably in sponges, is able to concentrate metals differently from the living tissue (Verdenal et al., 1990).
In fact, Sponges are well suited for the monitoring of type of chemical contamination. More studies are needed with representative sampling for species and locations to collect samples and to determine the appropriate bioindicator species.