Spelling suggestions: "subject:"medusae."" "subject:"hydromechanical.""
1 |
Spatiotemporal dsitribution of hydromedusae in the water off southern and northern TaiwanLin, Ping-chun 10 March 2010 (has links)
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.
|
2 |
Spatiotemporal distribution of hydromedusae in relation to hydrography in the waters surrounding TaiwanChang, Wan-chun 22 August 2008 (has links)
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.
|
3 |
Regeneration in hydroids.Davidson, Margaret E. M. January 1946 (has links)
No description available.
|
4 |
The chemical nature of diatom-derived settlement cue(s) of the marine polychaete hydroides elegans (Haswell) /Lam, Ka Sin. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.
|
5 |
Hydromedusae of the Canadian Eastern ArcticBarry, Barbara January 1974 (has links)
No description available.
|
6 |
Interannual changes in abundance and distribution of jellyfish along the west coast of South AfricaParker, Nausheena January 2015 (has links)
>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.
|
7 |
Hydromedusae of the Canadian Eastern ArcticBarry, Barbara January 1974 (has links)
No description available.
|
8 |
Diversidade e distribuição do zooplâncton gelatinoso sobre a plataforma continental e talude da Bacia de Campos (SE-Brasil)Silva, Paula Keshia Rosa January 2017 (has links)
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.
|
Page generated in 0.1474 seconds