Toxic effects of the polycyclic aromatic hydrocarbon fluoranthene (FLU) on life-history traits and their demographic consequences were investigated in 3 non-interbreeding Capitella sibling species with different physiological tolerances and developmental modes: sensitive Capitella sp. S from oxygen-rich intertidal sediments of the North Sea (Germany); tolerant Capitella sp. M from sediments near shallow hydrothermal vents off Milos (Greece), a habitat low in organic matter with steep abiotic gradients and high sulfide concentrations; tolerant Capitella sp. I from New York (USA), known to dominate eutrophicated/polluted environments. Both Capitella spp. M and I can develop into hermaphrodites and have lecithotrophic larval development. In contrast, Capitella sp. S appears to be dioecious and has direct development with benthic juveniles. In life-table-response experiments (LTRE), juveniles from the 3 species were raised under different FLU concentrations (0 to 95 µg g -1 FLU), and data on age-specific survival, growth and life-history parameters were recorded at weekly intervals. Under control conditions, the 3 Capitella species differed markedly in a number of life-history traits and population growth rates (λ), with Capitella sp. S showing the lowest λ (1.05), and Capitella sp. M the highest (1.42). Chronic exposure to inreasing FLU concentrations also revealed species-specific differences in individual-and population-level toxic responses. Highest FLU concentrations (95 µg g -1 ) markedly reduced juvenile survival and completely inhibited reproduction in Capitella sp. S, whereas individual life-history traits in Capitella spp. M and I were affected little, if at all. At the population level, the highest FLU exposures resulted in λ values of effectively zero in Capitella sp. S, whereas λ of Capitella spp. M and I remained >1. In conclusion, the combination of opportunistic life-history features, reproductive flexibility, and physiological adaptations enables Capitella spp. M and I to colonize habitats rapidly after local disturbance and to persist in stressed and unpredictable environments; whereas in Capitella sp. S, population extinction under toxicant stress mainly results from its physiological sensitivity.KEY WORDS: Capitella sibling species complex · Fluoranthene · Life-history traits · Benthic and lecithotrophic development · Population growth rateResale or republication not permitted without written consent of the publisher
SUMMARY: The development and growth of Capitella sp. B obtained from Barcelona were studied under culture conditions. Trochophore and metatrochophore larvae hatched non-simultaneously (two release periods) from single brood tubes. This is the first laboratory evidence of polymorphysm of sexual development in the Capitella capitata species-complex. During the "first release" period, only free swimming trochophores hatched. The females, still bearing larvae inside the brood tube, were transferred to another dish. After three days, ciliated metatrochophores hatched from 8.7% of the transferred broods. In a culture experiment, larvae maintained in sediment enriched with artificial food grew to immature and mature adults. In this condition, the larvae that hatched during the "first release" reached the immature adult stage, while the larvae derived from the "second release" became mature adults. Oogenesis was observed three times in one female from the second release, though no spawning and fertilization occurred under incubation with sib mature males. Two different sizes of coelomic oocytes were observed. Polymorphysm of sexual development is discussed as an advantageous reproductive strategy enhancing survival in organic enriched sediments.
Prophylactic HIG administration in pregnant women after CMV primary infection seems not to reduce significantly the rate of congenital infection, but is safe and it could have a favorable effect on the symptoms and sequelae of infected fetuses. The risk of long-term sequelae in fetuses without US abnormalities before HIG is low, so it could be an option in infected fetuses with normal imaging. On the other hand, the risk of sequelae among infected fetuses with abnormalities in fetal ultrasonography before HIG despite treatment is high.
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