Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Douglas C. Miller, College of Marine & Earth Studies. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: John Madsen, Dept. of Geological Sciences. Includes bibliographical references.

Reef habitats built by the tubiculous polychaete Sabellaria spinulosa have been identified as a habitat with significant conservation importance, based on their historic decline across Europe and the assumption that, like many other biogenic reef systems, S. spinulosa reefs enhance biodiversity. Despite the high conservation status of this habitat very little work has been undertaken to explore the role that S. spinulosa reefs play in marine ecosystems, or their sensitivity to anthropogenic disturbance. Observations of the reproductive ecology and population dynamics of the reef building organism indicate that S. spinulosa exhibit life-history traits typically associated with r-strategists, indicating that this species is likely to have the ability to recover quickly following most anthropogenic disturbance events. A series of surveys on S. spinulosa reefs identified at the Thanet Offshore Wind Farm site, where the extent of the reef habitat was found to have increased between the pre-construction and post construction survey despite extensive cable laying and turbine installation, corroborates these findings. Detailed investigations into the macrofauna associated with S. spinulosa reefs in the eastern English Channel revealed that S. spinulosa reefs support macrofaunal communities that are comparable to those associated with adjacent muddy sandy gravel and gravelly muddy sand in terms of species composition, taxonomic breadth and beta-diversity. A consistent enhancement in species richness, abundance and biomass was identified in samples collected from S. spinulosa reefs when compared with adjacent sedimentary deposits, as well as a corresponding reduction in the equitability of species, indicating that some macrofauna are able to exist in higher densities within this habitat. The increase in macrofaunal biomass associated with S. spinulosa reefs was found to influence the diet of demersal fish species, with some species feeding on the reef organism itself while others feed on species found in high densities on the reefs. The high abundance of juvenile flatfish associated with this habitat also suggests that S. spinulosa reefs may provide an important nursery habitat.

<p> Populations of three tubicolous polychaetes, Clymenella torquata, Spiophanes wisleyi and Sabellaria vulgaris located in the intertidal zone of the south shore of Cobequid Bay, Nova Scotia were studied for their effects on the surrounding sediment. Grain size measurements were made of the tubes and the surrounding sediment. T-tests were made on the resultant differences between the Inman sorting and mean statistics of the two sand populat ions . The percentages of heavy and light minerals were also measured with the use of a binocular microscope. The differences in sorting and mean grain size between the tubes and substrate may affect stability and porosity of the sediment and effect sediment structures easily identifiable in the geologic record. </p> <p> Clyrnenella torquata inhabits a low energy intertidal sandy envir onment and increases the porosity of the sediment by its feeding habits. Stabilization of the sediment may be effected by high population densities of Clymenella (densities around 420/m^2). Tubes were built with preferential grain sizes. Spiophanes wisleyi exists in phenomenally high population densities in low-energy areas. The large numbers of tubes (up to 98,000/m^2) bind the sediment; tubes are made of virtually the same grain sizes as the substrate; no bioturbation occurs during the construction of the tubes. The latter two factors make preservation potential very low in the geologic record. Sabellaria vulgaris in the study area is of little sedimentological importance. Population densities are too low to affect the surrounding substrate. This species exists in a high energy zone a characteristic of fauna which build reefs. Reef formation by sabellariids may have been important in the geologic past and is locally important today in the North Sea (Schafer, 1972) and Florida (Gram, 1968). </p> / Thesis / Bachelor of Science (BSc)

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2012-06-04T13:48:43Z No. of bitstreams: 2 Dissertacao_BiologiaReprodutivaSabellaria.pdf: 2745969 bytes, checksum: 0c3c913bd757fa1c9f88cc70a57b74bd (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Edisangela Bastos(edisangela@ufpa.br) on 2012-06-04T13:49:19Z (GMT) No. of bitstreams: 2 Dissertacao_BiologiaReprodutivaSabellaria.pdf: 2745969 bytes, checksum: 0c3c913bd757fa1c9f88cc70a57b74bd (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2012-06-04T13:49:19Z (GMT). No. of bitstreams: 2 Dissertacao_BiologiaReprodutivaSabellaria.pdf: 2745969 bytes, checksum: 0c3c913bd757fa1c9f88cc70a57b74bd (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2011 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O Polychaeta Sabellaria wilsoni ocorre a partir do Golfo do México até a Argentina, e constrói recifes de areia da zona intertidal até 25 m de profundidade. Esses recifes desempenham um papel importante na estruturação e funcionamento dos ecossistemas de praias arenosas na Costa da Amazônia. Este trabalho estudou a biologia reprodutiva de S. wilsoni na Ilha de Algodoal (PA, Brasil), descrevendo proporção entre os sexos, o processo gametogénicos e o período de reprodução. A amostragem ocorreu mensalmente entre maio de 2008 e abril de 2009. No laboratório 100 indivíduos foram escolhidos aleatoriamente e medidos (comprimento total - a partir do opérculo até o início do funil anal), e destes, 20 foram preparados para estudo histológico. As lâminas foram observadas em microscópio óptico para descrever estruturas reprodutivas, e para determinar o sexo e estágio de maturação. O tamanho dos organismos variou de 4,5 ± 1,89 milímetros para 11,5 ± 2,83 mm, com as fêmeas maiores e mais numerosas do que os machos (razão sexual 0.6:1 - M: F). Os gametas femininos se desenvolvem nas projeções dos vasos sanguíneos e são posteriormente liberadas no celoma. Nos machos a espermatogênese é associada aos septos intersegmentares, e o esperma é liberado no celoma. Gametas são liberados no meio externo por meio de nefrídios e a fecundação é externa. A reprodução ocorre durante todo o ano com picos em setembro-novembro e março-abril. Mas o principal fator para reprodução, é um aumento na hidrodinâmica em agosto, como uma adaptação do Polychaeta para a destruição de recifes futuro, que ocorre entre outubro e novembro, e um aumento de espaço disponível para a colonização, depois da destruição de recifes. / The Polychaeta Sabellaria wilsoni occurs from the Gulf of Mexico to Argentina, building sandy reefs from the intertidal zone to 25 m depth. These reefs play an important role in structuring and functioning of sandy beach ecosystems in the Amazon Coast. This work studied the reproductive biology of S. wilsoni in Algodoal Island (PA, Brazil), describing sex ratio, gametogenic process and breeding period. Sampling occurred monthly between May 2008 and April 2009. In the laboratory 100 individuals were randomly chosen and measured (total length – from the operculum to the beginning of the anal funnel); and from these, 20 specimens were prepared for histological studies. Slides were observed under optical microscope to describe reproductive structures, and to determine sex and maturation stage (based on a four grade scale). The size of organisms ranged from 4.5 ± 1.89 mm to 11.5 ± 2.83 mm, with females larger and more numerous than males (sex ratio 0.6:1 - M:F). Female gametes develop on projection of blood vessels and are subsequently released into the coelom. In males spermatogenesis is associated with intersegmental septa wall, and sperm is released into the coelom. Gametes are released to the environment through nephridia and fertilization is external. Reproduction occurs all year round with peaks on September-November and March-April. The main cues to reproduction are an increase in hydrodynamics on August, as an adaptation of the Polychaeta to the future reef destruction, which occurs between October and November; and an increase of space available for colonization, after the reef destruction.