SUMMARY
The biology and biochemistry of Gigartina pistillata (Gmelin) Stackhouse collected monthly at Nation Beach (Morocco), was studied during one year. The biological study showed one period of active growth from April to July. The thallus composition was quite stable during the major part of the year. The dry matter was maximum in May and August and minimum in January. The maximum carrageenan content occurred in June and September (about 37%) and the minimum carrageenan content occurred in February (19.0%). The total nitrogen content varied significantly, with a maximum in January (1.98%) and a minimum in August (0.7%). The ash content was significant (23–32%) with a maximum in August and a minimum in May. The carrageenan extracted from natural populations of Gigartina pistillata was a mixture of lambda‐type and kappa‐type carrageenans. The 3,6‐anhydrogalactose varied between 4.5 mol% in June to 25 mol% in February. For industrial applications the extract could be considered as a lambda‐type. The best period for harvest of G. pistillata in Morocco is between July and August when biomass and viscosity are at their maximum. A relationship between the physical characteristics of G. pistillata carrageenans and its seasonal cycle was deduced.
Le présent travail consiste à évaluer le degré de contamination de lestuaire de Bouregreg (Maroc) à travers le suivi spatio-temporel des teneurs de certains éléments métalliques (Cd, Cr, Cu, Fe, Pb et Zn) au niveau des sédiments et chez la moule Mytilus galloprovincialis. L'écosystème est soumis à de nombreux rejets complexes d'origine diverse. Une situation qui se complique davantage au niveau de l'estuaire par le jeu des marées rendant difficile l'évacuation aisée de la charge polluante résultant de l'activité anthropique.
Les résultats obtenus font état d'une contamination métallique généralisée le long de l'estuaire, importante pendant l'été au niveau des sédiments et pendant lhiver chez la moule. Le degré de contamination le plus élevé correspond au plomb avec des taux quatre fois supérieurs aux normes de la CEE. La consommation de la moule provenant de l'estuaire de Bouregreg reste redoutable et dangereuse quant aux risques toxicologiques que peut induire sa contamination.
Growth and reproductuive capacity of Hypnea musciformis (Rhodophyceae, Gigartinale) on the Moroccan Atlantic coast Carrageenan producing seaweeds represent an important biomass along the Atlantic coast of Morocco and are exported as raw material without any local transformation, while agar industry is well developed in the country. The aim of the present work is the valorisation of the more abundant seaweeds and their local transformation. Hypnea musciformis is one of the species studied in the laboratory and a potential applicant for exploitation. The first step before exploitation is to gather information about the biology and growth of this species in natural environment or under controlled conditions in the laboratory. The seasonal growth and reproductive ability of this species have been studied during 2 years on two different locations of Moroccan Atlantic coast. The species was fertile almost all along the year and tetrasporophyte phase predominated. H. musciformis has 2 periods of active growth: the first one at the beginning of summer and the second one, less active, in autumn. The biological cycle is under the influence of different environmental factors as light, temperature, salinity position of the thallus on the seashore and acclimatization response of the seaweed to different habitats.
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