3,542 research outputs found

    Three New Species of Saccocirrus (Polychaeta: Saccocirridae) from Hawai'i

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    Three new species of saccocirrids from interstitial sand habitats off O'ahu, Hawai'i, are described. Two are from subtidal depths, 9-33 m, and the third is from the intertidal to 3.5 m deep on a fringing reef and at Hanauma Bay, the Marine Life Conservation District and public park. The two deeper-water species, Saccocirrus oahuensis, n. sp. and S. waianaensis, n. sp., have 76-119 and 157-210 segments, respectively; they also have bilateral gonads but lack a pharyngeal pad. The third, S. alanhongi, n. sp., has 35-47 segments, unilateral gonads, and a muscular pharyngeal pad. These species are distinguished from 18 known Saccocirrus spp. by their unique chaetation, number of segments, presence or absence of ventral cilia, and pygidial adhesive structures. Saccocirms oahuensis consumes foraminiferans, and S. alanhongi contained diatoms, unicellular algae, and ostracods. These species add to the interstitial fauna of O'ahu and cooccur with polychaetes Nerilla antennata (Nerillidae) and protodrilids (Protodrilidae), and Kinorhyncha. Saccocirrus alanhongi withstands almost daily disturbance by 600-1200 bathers per day entering the sandy swimming holes in the reef at Hanauma Bay

    Sediment trapping by chaetopterid polychaetes on a Hawaiian fringing reef

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    The role of chaetopterid polychaetes in determining sediment grain-size composition and community structure on a south shore fringing reef flat of Oahu, Hawaii was examined. Quantitative samples taken from within and adjacent to dome-shaped mounds of chaetopterid tubes along a shore to seaward gradient were analyzed for grain size and fauna! composition....

    El desarrollo larvario de Sabellastarte spectabilis (Grube, 1878) (Polychaeta: Sabellidae) en Hawaii

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    The sabellid polychaete Sabellastarte spectabilis is common in bays and harbours throughout Hawaii. It has become one of the most harvested marine ornamental species in the State. Collection can be difficult and potentially damaging to the reef community. Understanding the reproduction and life history of this polychaete will benefit the marine ornamental trade by facilitating aquaculture of the species and coral reef conservation by decreasing destructive collecting practices. There is very little known about the biology of this species. Experiments were conducted at the Hawaii Institute of Marine Biology to induce and document spawning and larval development. Oocytes range between 150-200 µm in diameter and sperm have spherical heads. Cell division in fertilized eggs begins approximately twenty minutes after spawning. Developmental stages were documented using light and scanning electron microscopy. Swimming larvae are first seen 7-8 h after spawning. Larvae have a well-developed prototroch and a less conspicuous neurotroch and metatroch. Two chaetigers develop sequentially on days 4 and 5 and settlement occurs 6-7 days after spawning. Metamorphosis occurs gradually from days 6-8. This is the first reported induction of spawning and description of larval development from fertilized egg to settlement and metamorphosis for this species.El poliqueto sabélido Sabellastarte spectabilis es común en bahías y puertos de Hawaii. Este sabélido ha llegado a ser una de las especies ornamentales marinas más recolectadas en el estado, pero su recolección es difícil y en muchos casos ocasiona daño a la comunidad arrecifal. Pese a ello, el conocimiento sobre su biología es escaso. El estudio de la reproducción y ciclo de vida de estos sabélidos facilitará su cultivo y beneficiará al mercado de especies ornamentales, a la vez que la diminución de la recogida destructiva se espera pueda contribuir a la conservación de los arrecifes coralinos. En el Hawaii Institute of Marine Biology se realizaron algunos experimentos con la finalidad de inducir y documentar su reproducción y desarrollo larvario. Los huevos miden entre 150-200 μm de diámetro y los espermatozoos presentan cabezas redondas. La división celular de huevos fertilizados comienza aproximadamente 20 minutos después del desove. Los estadios larvarios se documentaron con microscopios de luz y microscopia electrónico de barrido. Las primeras larvas aparecen 7-8 horas después del desove. Las larvas tienen una prototroca muy bien desarrollada y una neurotroca y metatroca menos conspicua. Entre los días 4 y 5 se desarrollan dos setígeros y el reclutamiento ocurrió 6-7 días después del desove. La metamorfosis ocurre gradualmente entre los días 6-8. Este estudio describe por primera vez la inducción del desove y la descripción del desarrollo larvario desde la fertilización del huevo hasta el establecimiento y metamorfosis de la especie. &nbsp

    The genus Boccardia (Polychaeta: Spionidae) associated with mollusc shells on the south coast of South Africa

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    Three species of Boccardia (B. polybranchia, B. pseudonatrix and B. proboscidea) were associated with mollusc shells on the south and south-east coasts of South Africa. Boccardia polybranchia was widely distributed along the coast and falls within the known distribution range of this species. Comparisons with material from other, international, locations showed that some specimens have been misidentified. No characters could be found to characterize distinct species for different regions within the range of B. polybranchia, as currently recognized. Boccardia pseudonatrix was found only at the most eastern site, increasing its known distribution range. Boccardia proboscidea, a non-indigenous species, was found only on abalone farms and was most abundant in the west

    Successful transition to secondary school in Tanzania: What are the barriers?

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    Transition to secondary school is a problem internationally. Tanzanian students face an additional challenge as the medium of instruction changes from Kiswahili to English. An 18-item questionnaire (N = 383) and focus groups (primary standard 7, secondary forms 1 and 3, and primary and secondary teachers) were used in this study. Most students started secondary school with high expectations. These were qualified by experiences of bullying and punishment. Teachers recognised students losing hope as an explanation for truancy. However, they lacked both the training to teach English and knowledge of alternatives to punishment. Peer mentoring potentially addresses these challenges during transition

    Negative phenotypic and genetic associations between copulation duration and longevity in male seed beetles

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    Reproduction can be costly and is predicted to trade-off against other characters. However, while these trade-offs are well documented for females, there has been less focus on aspects of male reproduction. Furthermore, those studies that have looked at males typically only investigate phenotypic associations, with the underlying genetics often ignored. Here, we report on phenotypic and genetic trade-offs in male reproductive effort in the seed beetle, Callosobruchus maculatus. We find that the duration of a male's first copulation is negatively associated with subsequent male survival, phenotypically and genetically. Our results are consistent with life-history theory and suggest that like females, males trade-off reproductive effort against longevity
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