Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: marine invertebrates

Sortuj według:

Ogranicz wyniki do:

Larval development and settlement of the barnacle Amphibalanus amphitrite from the Red Sea : Influence of the nauplii hatching season

Al-Aidaroos A.M., Satheesh S.

Oceanological and Hydrobiological Studies

2014

Vol. 43, No. 2

170--177

Barnacle Amphibalanus amphitrite adults were collected from the Jeddah coast of the Red Sea during different seasons. The nauplii released by adults in autumn, winter, spring and summer were reared under laboratory conditions to know the larval development duration and settlement in relation to the hatching season. The nauplii reared during winter (11 days) and autumn (13 days) took longer to reach the cypris stage compared to nauplii reared in summer (6 days) and spring (7 days). The most successful settlement of larvae was observed in spring and summer and the least successful — in winter. The observations of gonads showed that summer and spring are the active breeding season for A. amphitrite in the Red Sea. The results of this study indicated that the nauplii hatching season plays a significant role in the larval development and settlement of barnacles in the Red Sea.

Applied radiotracer techniques for studying pollutant bioaccumulation in selected marine organisms (jellyfish, crabs and sea stars)

Fowler S., Teyssié J., Cotret O., Danis B., Rouleau C., Warnau M.

Nukleonika

2004

Vol. 49, nr 3

97-100

Obtaining specific information on contaminant biokinetics in marine biota is often necessary for properly interpreting monitoring data on trace contaminant levels in bioindicator species living under varying environmental conditions. Radiotracers have been employed in laboratory experiments to assess the uptake, distribution and retention of selected heavy metals and PCB congeners in three potential marine bioindicators occupying different ecological niches in the coastal zone. Pelagic and benthic jellyfish readily accumulated Co, Ag, Zn, Cd, 137Cs and 241Am from both water and food and retained them with biological half-lives (Tb1/2) ranging from a few days to several weeks. Zinc and silver were accumulated to the greatest degree (CF ~ 4 ´ 102), with benthic jellyfish having a greater affinity for metals than the pelagic species. Results from light–dark experiments indicate that the enhanced metal uptake in the benthic jellyfish is due to the presence of endosymbiotic photosynthetic zooxanthellae situated in the arms of organisms. Shore crabs ingesting Ag, a sewage-related contaminant, readily accumulated the metal with male crabs assimilating some 71% and female crabs 51% of the Ag from their food. Moreover, the assimilated fraction of Ag remained virtually immobile in their tissues as evidenced by an extremely long Tb1/2 for depuration of 7.3 years. Sea stars exposed to 14C-labelled PCB congener #153 in sea water accumulated the congener mainly in the body wall and podia reaching lipid weight CFs that ranged between approximately 2 x 10 5 to 4 x 10 5. In contrast, following exposure in radio-labelled sediments, the corresponding PCB transfer factors in the same tissues were much lower, viz., 3 x 10 2 to 5 x 10 2. Nevertheless, regardless of the exposure mode, CFs of PCB in the other tissues (digestive system, gonads, pyloric and rectal caeca) were consistently one to two orders of magnitude lower, an observation which suggests that sea star body wall and podia could serve as target tissues in biomonitoring studies assessing these toxic compounds.