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Masanori Hiraoka - One of the best experts on this subject based on the ideXlab platform.
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Persistent occurrence of floating Ulva green tide in Hiroshima Bay, Japan: seasonal succession and growth patterns of Ulva pertusa and Ulva spp. (Chlorophyta, Ulvales)
Hydrobiologia, 2015Co-Authors: Goro Yoshida, Masayuki Uchimura, Masanori HiraokaAbstract:Since the late 1980’s, a persistent green tide of floating Ulva without any clear seasonal fluctuation has occurred in Hiroshima Bay, Seto Inland Sea, Japan. We hypothesized that the persistence is due to the co-existence of Ulva species with different seasonal growth patterns, and monitored the seasonal composition and growth characteristics of the constituent Ulva within the green tide. Two morphological types of Ulva were identified, and one type, U. pertusa , was almost the sole constituent during winter and spring. The other type Ulva spp., which has marginal microscopic serrations on the thallus, was dominant during summer and autumn. Both Ulva showed the highest relative growth rate in early autumn, but growth of Ulva spp. was faster in summer than that of U. pertusa and inhibited in winter. U. pertusa had more eurythermal characteristics in which the growth rate remained relatively high in winter. Water temperature was the most correlated Environmental Variable for the seasonal growth of both Ulva types rather than light or nutrients, but more influential on Ulva spp. Recent increasing trend of ambient seawater temperature is considered to be favorable for the growth of both Ulva types and a causative factor of the green tide.
Martiwi Diah Setiawati - One of the best experts on this subject based on the ideXlab platform.
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characterization of bigeye tuna habitat in the southern waters off java bali using remote sensing data
Advances in Space Research, 2015Co-Authors: Martiwi Diah Setiawati, Abu Bakar Sambah, Tasuku Tanaka, Fusanori Miura, Abd Rahman AssyakurAbstract:Bigeye tuna (Thunnus obesus) habitat was investigated based on catch data and Environmental satellite data, such as sea surface temperature (SST), sea surface chlorophyll (SSC), and sea surface height deviation (SSHD) data in the Southern Waters off Java and Bali. First, we obtained daily fish catch data and monthly satellite data for SST, SSC, and SSHD for 2006–2010. Then, we analyzed the relationship between daily catch data and satellite data by combining the statistical method of generalized additive model (GAM) and geographic information system (GIS). Seven GAM models were generated with the number of bigeye tuna as a response Variable, and SST, SSC, and SSHD as predictor Variables. All of the predictors of SST, SSC, and SSHD were highly significant (P < 0.001) to the number of bigeye tuna. Values of SST, SSHD, and SSC in bigeye tuna habitat ranged from 24.8 to 28.7 °C, −3 to 7 cm, and 0.05 to 0.17 mg/m3, respectively. Validation of the predicted number of bigeye tuna with the observed value was significant (P < 0.05, r2 = 0.56). SST was the most important Environmental Variable to the number of bigeye tuna caught, followed by SSHD and SSC.
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Characterization of bigeye tuna habitat in the Southern Waters off Java–Bali using remote sensing data
Advances in Space Research, 2015Co-Authors: Martiwi Diah Setiawati, Tasuku Tanaka, Abu Bakar Sambah, Fusanori Miura, Abd. Rahman As-syakurAbstract:Bigeye tuna (Thunnus obesus) habitat was investigated based on catch data and Environmental satellite data, such as sea surface temperature (SST), sea surface chlorophyll (SSC), and sea surface height deviation (SSHD) data in the Southern Waters off Java and Bali. First, we obtained daily fish catch data and monthly satellite data for SST, SSC, and SSHD for 2006–2010. Then, we analyzed the relationship between daily catch data and satellite data by combining the statistical method of generalized additive model (GAM) and geographic information system (GIS). Seven GAM models were generated with the number of bigeye tuna as a response Variable, and SST, SSC, and SSHD as predictor Variables. All of the predictors of SST, SSC, and SSHD were highly significant (P < 0.001) to the number of bigeye tuna. Values of SST, SSHD, and SSC in bigeye tuna habitat ranged from 24.8 to 28.7 °C, −3 to 7 cm, and 0.05 to 0.17 mg/m3, respectively. Validation of the predicted number of bigeye tuna with the observed value was significant (P < 0.05, r2 = 0.56). SST was the most important Environmental Variable to the number of bigeye tuna caught, followed by SSHD and SSC.
Erik Jeppesen - One of the best experts on this subject based on the ideXlab platform.
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responses of trophic structure and zooplankton community to salinity and temperature in tibetan lakes implication for the effect of climate warming
Water Research, 2017Co-Authors: Lei Xu, Erik JeppesenAbstract:Abstract Warming has pronounced effects on lake ecosystems, either directly by increased temperatures or indirectly by a change in salinity. We investigated the current status of zooplankton communities and trophic structure in 45 Tibetan lakes along a 2300 m altitude and a 76 g/l salinity gradient. Freshwater to hyposaline lakes mainly had three trophic levels: phytoplankton, small zooplankton and fish/Gammarus, while mesosaline to hypersaline lakes only had two: phytoplankton and large zooplankton. Zooplankton species richness declined significantly with salinity, but did not relate with temperature. Furthermore, the decline in species richness with salinity in lakes with two trophic levels was much less abrupt than in lakes with three trophic levels. The structural variation of the zooplankton community depended on the length of the food chain, and was significantly explained by salinity as the critical Environmental Variable. The zooplankton community shifted from dominance of copepods and small cladoceran species in the lakes with low salinity and three trophic levels to large saline filter-feeding phyllopod species in those lakes with high salinity and two trophic levels. The zooplankton to phytoplankton biomass ratio was positively related with temperature in two-trophic-level systems and vice versa in three-trophic-level systems. As the Tibetan Plateau is warming about three times faster than the global average, our results imply that warming could have a considerable impact on the structure and function of Tibetan lake ecosystems, either via indirect effects of salinization/desalinization on species richness, composition and trophic structure or through direct effects of water temperature on trophic interactions.
Louise A. Kelly-hope - One of the best experts on this subject based on the ideXlab platform.
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Environmental factors associated with the distribution of Loa loa vectors Chrysops spp. in Central and West Africa: seeing the forest for the trees
Parasites & Vectors, 2019Co-Authors: Xavier Badia-rius, David H. Molyneux, Hannah Betts, Louise A. Kelly-hopeAbstract:BackgroundLoiasis is caused by the filarial parasite Loa loa , which is widespread through Central and West Africa and largely confined the tropical equatorial rainforests. The tabanid flies Chrysops silacea and Chrysops dimidiata are the main vectors driving transmission. This study aimed to better define the spatial distribution and ecological niche of the two vectors to help define spatial-temporal risk and target appropriate, timely intervention strategies for filariasis control and elimination programmes.MethodsChrysops spp . distributions were determined by collating information from the published literature into a database, detailing the year, country, locality, latitude/longitude and species collected. Environmental factors including climate, elevation and tree canopy characteristics were summarised for each vector from data obtained from satellite modelled data or imagery, which were also used to identify areas with overt landcover changes. The presence of each Chrysops vector was predicted using a maximum entropy species distribution modelling (MaxEnt) method.ResultsA total of 313 location-specific data points from 59 published articles were identified across seven loiasis endemic countries. Of these, 186 sites were included in the climate and elevation analysis, and due to overt landcover changes, 83 sites included in tree canopy analysis and MaxEnt model. Overall, C. silacea and C. dimidiata were found to have similar ranges; annual mean temperature (24.6 °C and 24.1 °C, respectively), annual precipitation (1848.6 mm and 1868.8 mm), elevation (368.8 m and 400.6 m), tree canopy cover (61.4% and 66.9%) and tree canopy height (22.4 m and 25.1 m). MaxEnt models found tree canopy coverage was a significant Environmental Variable for both vectors.ConclusionsThe Chrysops spp. database and large-scale Environmental analysis provides insights into the spatial and ecological parameters of the L. loa vectors driving transmission. These may be used to further delineate loiasis risk, which will be important for implementing filariasis control and elimination programmes in the equatorial rainforest region of Central and West Africa.
Goro Yoshida - One of the best experts on this subject based on the ideXlab platform.
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Persistent occurrence of floating Ulva green tide in Hiroshima Bay, Japan: seasonal succession and growth patterns of Ulva pertusa and Ulva spp. (Chlorophyta, Ulvales)
Hydrobiologia, 2015Co-Authors: Goro Yoshida, Masayuki Uchimura, Masanori HiraokaAbstract:Since the late 1980’s, a persistent green tide of floating Ulva without any clear seasonal fluctuation has occurred in Hiroshima Bay, Seto Inland Sea, Japan. We hypothesized that the persistence is due to the co-existence of Ulva species with different seasonal growth patterns, and monitored the seasonal composition and growth characteristics of the constituent Ulva within the green tide. Two morphological types of Ulva were identified, and one type, U. pertusa , was almost the sole constituent during winter and spring. The other type Ulva spp., which has marginal microscopic serrations on the thallus, was dominant during summer and autumn. Both Ulva showed the highest relative growth rate in early autumn, but growth of Ulva spp. was faster in summer than that of U. pertusa and inhibited in winter. U. pertusa had more eurythermal characteristics in which the growth rate remained relatively high in winter. Water temperature was the most correlated Environmental Variable for the seasonal growth of both Ulva types rather than light or nutrients, but more influential on Ulva spp. Recent increasing trend of ambient seawater temperature is considered to be favorable for the growth of both Ulva types and a causative factor of the green tide.