Temporal and spatial distribution in species composition and abundance of hydromedusae in relation to hydrographic variables in the waters off southern and northern Taiwan were investigated from January 2005 to July 2006. In total, 46 hydromedusae species belonging to 26 genera and 18 families were identified in the waters off southern Taiwan, with mean abundance of 88¡Ó14 inds./1000m3. The abundance of hydromedusae showed distinct seasonal change, higher in January 2005 and July 2006 compared with other seasons. The predominant species were Aglaura hemistoma, Amphogona apsteini and A. apicata, together they contributed to 71 % of the numerical total of hydromedusae. In the waters off northern Taiwan, 36 hydromedusae species belonging to 24 genera and 19 families were identified, with mean abundance of 235¡Ó68 inds./1000m3. The abundance of hydromedusae showed no apparent seasonal change. The 2 most dominant species, A. hemistoma and Eutima levuka, comprised 70.3 % of the numerical total of hydromedusae. The mean species number and species diversity were higher in the southern waters than the northern waters of Taiwan, but the overall mean abundance was about 3 times higher in the northern waters than that in the southern waters, particularly in the northwestern waters off Taiwan. Different dominant species showed different distribution patterns. In total, the species number and species diversity index of hydromedusae in the present study areas showed significantly positive correlation with water temperature, while the abundance and species richness of hydromedusae and the dominant species showed significantly positive correlation with zooplankton. The dominant species, E. levuka, showed significantly negative correlation with water salinity. The species diversity was always higher in the waters off southern Taiwan, probably due to warm and stable hydrographic conditions. The abundance of most dominant species were positively correlated to zooplankton abundance in the southern waters, suggesting that the abundance of food availability might also be a key factor to determine the distribution pattern of hydromedusae. While in the waters off northern Taiwan, seasonal variation of hydrography was more obvious than that in the waters off southern Taiwan, and so as the species number and the species diversity index of hydromedusae, implied that the distribution of hydromedusae was closely related to the seasonal variation of water masses.

Temporal and spatial distribution in species composition and abundance of hydromedusae in relation to hydrographic variables in the waters surrounding Taiwan were investigated from February to November, 2004. A total of 101 species belonging to 65 genera and 34 families hydromedusae were identified, with the mean abundance of 557 ¡Ó 90 inds./1000m3. The abundance of hydromedusae showed no significant seasonal change but generally was higher in spring and fall, and lower in summer. The eight dominant species were Aglaura hemistoma¡BSolmundella bitentaculata¡BEutima levuka¡BLiriope tetraphylla¡BAglantha elata¡BLaodicea indica¡BRhopalonema velatum and Sminthea eurygaster, which together contributed 85% of the total hydromedusae. Hydromedusae showed higher abundance in the waters northwest off Taiwan, while the species number and diversity were higher in the waters east and south off Taiwan. Hydromedusa communities showed significant difference among water masses, higher abundance in China Costal Current, meanwhile higher species number and diversity in Kuroshio Current. Different dominant species showed different distribution patterns. The total abundance of hydromedusae showed no significant correlation with temperature or salinity, but were positive correlated with zooplankton abundance, while species richness were negatively correlated with zooplankton abundance. Different dominant hydromedusae species showed different correlationships with environmental factors; Aglaura hemistoma showed significant positive correlation with salinity, but Solmundella bitentaculata showed significant negative corelation with salinity. The correlationship between the abundance of each dominant species and evironmental factors varied seasonally.

No description available.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

No description available.

>Magister Scientiae - MSc / Hydromedusae are mostly carnivorous planktivores that under ideal conditions can reproduce and accumulate to form dense masses of jellyfish, known as blooms. These jellyfish blooms may have various impacts on their surrounding biota and in severe cases have the potential to result in ecosystem-wide changes. This study investigated assemblages of hydromedusae within the southern Benguela ecosystem, between the years 2000 and 2006. The samples analyzed were collected as part of routine Spawner Biomass Surveys conducted by the Department of Environmental Affairs: Ocean and Coasts (previously Marine and Coastal Management) using Bongo nets. Two hundred and forty two of the samples collected during the spring months, October and November, were analyzed. Environmental variables including (amongst others) sea surface temperature (SST), sea surface salinity (SSS), sea surface oxygen (SSO) and fluorescence (as a proxy for Chlorophyll a concentration) were measured to observe their influence on medusoid assemblages, distribution, abundance and diversity. Assemblages of hydromedusae were represented by 69 species and were dominated by Siphonophora and Leptomedusae. Mean abundance of hydromedusae were highest in 2005 (3.15 ind.m-³, SD 3.21) and lowest in 2002 (0.50 ind.m-³, SD 0.70). Trends in abundance displayed a general bell-shaped curve relationship with SST. The random-effects meta-analysis model revealed, across all years and all medusaoid classes that SSS (R=0.469), latitude (R=0.223), bottom fluorescence (R=0.533), mean fluorescence (R=0.338) and volume filtered (R=-0.408) were all significant factors in driving medusoid abundance at p<0.05. Medusoid diversity displayed a positive correlation to both temperature and salinity. A BIOENV analysis was used to explore the environmental factors that best described the variation observed in the biological assemblages. The results from this analysis suggest that SSS and bottom oxygen (BO) are the environmental factors that most influence the composition of medusoid assemblages.

No description available.

Orientador: Prof. Dr. Otto Müller Patrão de Oliveira / Coorientador: Prof. Dr. Renato Mitsuo Nagata / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Evolução e Diversidade, São Bernardo do Campo, 2017. / Com uma grande extensão de costa marítima, o Brasil apresenta diversas lacunas no conhecimento acerca da faunística, ecologia e biogeografia de diversos grupos zoológicos. Para as regiões mesopelágicas e batipelágicas a escassez de informação é ainda mais marcante em especial para os grupos do chamado zooplâncton gelatinoso. Dentre os organismos marinhos gelatinosos, os Hydrozoa são um dos grupos mais abundantes e diversos no plâncton. Como predadores, constituem um importante elo na teia trófica pelágica, podendo potencialmente afetar a distribuição e abundância de espécies de interesse econômico e consequentemente impactar algumas atividades humanas. Assim, o conhecimento acerca da diversidade e distribuição dos hidrozoários planctônicos tende a contribuir para estudos e planejamentos nas áreas de pesca e conservação de ambientes marinhos. O objetivo do presente estudo foi de caracterizar a diversidade e a distribuição dos hidrozoários da plataforma continental e o talude (até 3000m de profundidade) da Bacia de Campos, oriundas das campanhas realizadas pelo projeto HABITATS, durante o período chuvoso e seco de 2009. Os dados foram analisados procurando inferir as relações entre a composição e diversidade das espécies com as massas de água características da região. Foram analisadas 645 amostras sendo divididas em 303 amostras de hidromedusas e 342 amostras de sifonóforos totalizando 28.926 espécimes de Hydrozoa, correspondendo a 73 espécies das quais 44 são sifonóforos. Todas as espécies encontradas já haviam sido previamente registradas no litoral brasileiro. As espécies Aglaura hemistoma, Diphyes bojani, Eudoxoides spiralis, Liriope tetraphyla e Muggiaea kochii foram as espécies dominantes. As espécies Aglaura hemistoma e Diphyes bojani foram encontradas em todas as massas de água analisadas, em ambos os períodos, com significativas contribuições para a composição das comunidades de todas as massas de água. Foi possível correlacionar as espécies Aglaura hemistoma, Liriope tetraphylla e Corymorpha gracilis com a Água Tropical (AT), enquanto as espécies Sminthea eurygaster, Amphogona apicata e Lensia conoidea foram indicativas da Água Central do Atlântico Sul (ACAS), e por fim, Lensia havock e Halicreas minimum foram indicativas da Água Intermediária Antártica (AIA). Quanto a comunidade de sifonóforos, a AT foi caracterizada pela presença de Muggiaea kochii, Diphyes bojani, Abylopsis tetragona, Abylopsis eschscholtzii, Eudoxoides spiralis, Bassia bassensis e Chelophyes appendiculata. A espécie M. kochi caracterizou as regiões mais rasas da plataforma e teve abundâncias decrescentes em direção às regiões de maior profundidade. Em geral, as variáveis ambientais tiveram baixa explicação (aproximadamente 10%) para a variabilidade das densidades da comunidade de hidrozoários planctônicos. As maiores correlações entre as variáveis ambientais e as densidades de sifonóforos foram observadas na AT, em que explicaram aproximadamente 40% da variação da comunidade. Dessa forma, os sifonóforos tiveram uma melhor correlação com a variabilidade ambiental do que as hidromedusas para a AT. No geral, as espécies de sifonóforos tiveram suas distribuições mais restritas a determinadas massas de água, enquanto para as hidromedusas as preferências por massas de água não foram tão claras. Mesmo com a baixa correlação entre as variáveis ambientais e os hidrozoários foi possível ampliar o conhecimento acerca da distribuição vertical das espécies, além de caracterizar possíveis correlações das espécies com as principais variáveis ambientais. / With a large extension, the Brazilian coast has several gaps on the knowledge of faunistic, ecology and biogeography of some zoological groups. For the mesopelagic and bathypelagic regions, the scarcity of information is even more evident, especially for the gelatinous zooplankton. Among the marine gelatinous organisms, hydrozoans are one of the most abundant and diverse groups in the plankton. As predators, they comprise an important link in the pelagic trophic web, potentially affecting the distribution and abundance of species of economic interest, consequently, affecting human activities. Thus, the knowledge about planktonic hydrozoans diversity and distribution contribute to studies on fisheries and conservation of marine environment. The aim of this study was to describe the diversity and distribution of hydrozoans over the continental shelf and slope (until 3000m deep) of the Campos Basin (RJ), from campaigns performed by the HABITATS project, during the rainy and dry seasons of 2009. The data was analyzed aiming to infer the possible relationships between species composition and diversity with the local water masses. A total of 645 samples were analyzed divided in 303 samples of hydromedusae and 342 samples of Siphonophorae totalizing 28,926 specimens of Hydrozoa, corresponding to 73 species, 44 of siphonophores and 29 hydromedusae. All species found have previous records for the Brazilian coast. Aglaura hemistoma, Diphyes bojani, Eudoxoides spiralis, Liriope tetraphylla and Muggiaea kochii were the dominant species. The species Aglaura hemistoma and Diphyes bojani were present in all analyzed water masses, in both seasons, with significant contribution for the community composition of all water masses. Furthermore, the species A. hemistoma, L. tetraphylla and Corymorpha gracilis were associated with the Tropical water (TW), while Sminthea eurygaster, Amphogona apicata and Lensia conoidea were indicative of the South Atlantic Central Water (SACW), and finally Lensia havock and Halicreas minimum were indicative of Antartic Intermediate Water (AAIW). The Siphonophorae community in TW was characterized by the presence of M. kochii, D. bojani, Abylopsis tetragona, Abylopsis eschscholtzii, E. spiralis, Bassia bassensis and Chelophyes appendiculata. The species M. kochii characterized shallow continental shelf waters with decreasing abundance toward deeper regions. In general, environmental variables had low explanation (about 10%) to the variability in the densities of planktonic hydrozoans community. The highest correlation between environmental variables and the siphonophores densities were found in TW, which explained nearly 40% of the community variation. Siphonophorae were better environment indicative than the hydromedusa to TW. Therefore, the siphonophores had higher correlation with environmental variability than hydromedusae in the TW. Overall, the Siphonophorae species had their distribution restrict to determined water masses while the hydromedusae preferences for water masses were unclear. Even with the low correlation between the environmental variables and the Hydrozoa species was possible do increase the actual knowledge about species vertical distribution, besides characterizing possible relationships of the species with the main environmental variables.