22 results on '"YOSHITAKE TAKADA"'
Search Results
2. Spatial hierarchical partitioning of macrobenthic diversity of clam ( Ruditapes ) fishing grounds over a large geographical range of Japan
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Mutsumi Tsujino, Hiroaki Kurogi, Naoaki Tezuka, Shuhei Sawayama, Yuka Ishihi, Motoharu Uchida, Yoshitake Takada, and Satoshi Watanabe
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Fishery ,Geography ,biology ,Range (biology) ,Null model ,Fishing ,Spatial ecology ,Ruditapes ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Diversity (business) - Published
- 2020
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3. Cross‐shore distributions of peracarid crustaceans after changes in beach morphology: The importance of suction as a key geoenvironmental variable
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Shinji Sassa, Soonbo Yang, and Yoshitake Takada
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Shore ,geography ,Suction ,geography.geographical_feature_category ,biology ,Species distribution ,Morphology (biology) ,Monsoon ,biology.organism_classification ,Crustacean ,Oceanography ,Key (lock) ,Environmental science ,Ecology, Evolution, Behavior and Systematics - Published
- 2020
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4. Estimates of mortality in sandy beach populations of Haustorioides japonicus (Amphipoda: Crustacea) and Excirolana chiltoni (Isopoda: Crustacea) during winter storm seasons
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Naoto Kajihara, Shinji Sassa, Yuya Suzuki, Soonbo Yang, Yoshitake Takada, and Kazunori Yamahira
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Haustorioides japonicus ,Amphipoda ,Disturbance (geology) ,Ecology ,biology ,Winter storm ,Aquatic Science ,Oceanography ,biology.organism_classification ,Monsoon ,Crustacean ,Isopoda ,Geography ,Ecology, Evolution, Behavior and Systematics ,Excirolana chiltoni - Published
- 2019
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5. Universality of the linkage between geoenvironment and the distributions of three Haustorioides amphipods: H. japonicus, H. munsterhjelmi, and H. koreanus
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Shinji Sassa, Soonbo Yang, and Yoshitake Takada
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Ecology ,Evolutionary biology ,Haustorioides ,Environmental science ,Aquatic Science ,Oceanography ,Ecology, Evolution, Behavior and Systematics ,Universality (dynamical systems) - Published
- 2019
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6. Environmental factors affecting benthic invertebrate assemblages on sandy shores along the Japan Sea coast: implications for coastal biogeography
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Yoshitake Takada, Shota Mochizuki, Naoto Kajihara, Hideki Sawada, and Takuhiko Murakami
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0106 biological sciences ,Shore ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,010604 marine biology & hydrobiology ,Biogeography ,Fetch ,01 natural sciences ,Sea surface temperature ,Oceanography ,Benthic zone ,Ordination ,Ecology, Evolution, Behavior and Systematics ,Geology ,0105 earth and related environmental sciences ,Swash ,Invertebrate - Abstract
Assemblages of sandy shores are primarily structured by physical environment factors. This structuring provides a unique opportunity to evaluate biogeographic regions. In this study, the shallow subtidal zone (0.2–1.2 m) of 39 sites of sandy shores along the Japan Sea coast of Honshu were surveyed using a sledge net to identify invertebrate assemblages and to elucidate their relationships with environmental factors and geographic distributions. In total, 78 taxonomic units were obtained and six clusters of assemblage were recognized according to the Morisita-Horn dissimilarity index values between the assemblages of these sites. Indicator taxonomic units were identified for the clusters and a distance-based redundancy analysis (dbRDA) demonstrated that a set of five environmental factors (slope angle of the swash zone, sediment grain size, average wave fetch, spring sea surface temperature, and summer Chlorophyll-a concentration) significantly explained variations of the assemblages. Geographical distributions of two of the clusters were localized and mutually exclusive (one in the north and one in the south), while the other four clusters were scattered along the coast. On the dbRDA ordination, these two clusters were plotted on opposite ends of the 1st axis on which spring sea surface temperature and summer Chlorophyll-a concentration showed high contributions. The spatial gap between the two clusters was located in an area between the Noto Peninsula and the Sado Island, central Honshu, which can be proposed as a boundary of geographic regions of sandy shore organisms along the Japan Sea coast. more...
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- 2017
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7. Colonization of coral rubble by motile cryptic animals: Differences between contiguous versus raised substrates from the bottom
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Takuro Shibuno, Osamu Abe, Yoshitake Takada, and Kazumasa Hashimoto
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0106 biological sciences ,geography ,geography.geographical_feature_category ,Ecology ,010604 marine biology & hydrobiology ,Coral ,fungi ,Rubble ,Coral reef ,Aquatic Science ,engineering.material ,Plankton ,Biology ,010603 evolutionary biology ,01 natural sciences ,Substrate (marine biology) ,Water column ,Benthic zone ,engineering ,Colonization ,Ecology, Evolution, Behavior and Systematics - Abstract
Recent studies have demonstrated that interstices of coral rubble harbor rich and diverse assemblages of motile cryptic animals. Habitats of coral rubble are prone to frequent physical disturbances, so colonization is an important process to maintain the assemblages of these cryptic animals. In order to examine the pattern of colonization, field experiments were carried out using mesh traps with defaunated coral rubble: one treatment placed on the bottom and the other raised 15 cm above the bottom (throughout as “raised”) to restrict colonizers to only organisms that are able to invade via the water column. Results of nMDS and PERMANOVA showed significant differences between the assemblages of the bottom and raised treatments. Species-specific variations in the rate of colonization, which were estimated by fitting the von Bertalanffy equation, contributed to the variations in the cryptic assemblages. Generally, decapods and gastropods colonized via the benthic pathway with colonizing individuals moving on the surface of the bottom substrate, while copepods and non-shelled gammarids colonized via the planktonic pathway. Variations in cryptic assemblages in coral rubble microhabitats may be partly due to differences in contributions via the two colonization pathways. more...
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- 2016
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8. Zonation of macrofaunal assemblages on microtidal sandy beaches along the Japan Sea coast of Honshu
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Shin-ichiro Abe, Yoshitake Takada, Naoto Kajihara, Tomoaki Iseki, and Yuta Yagi
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0106 biological sciences ,Amphipoda ,Ecology ,biology ,010604 marine biology & hydrobiology ,Aquatic Science ,Oceanography ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Isopoda ,Sea coast ,Ecology, Evolution, Behavior and Systematics ,Geology - Published
- 2016
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9. Morisita’s prosperity index revisited
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Yoshitake Takada
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Index (economics) ,Ecology ,Gamma diversity ,media_common.quotation_subject ,Biodiversity ,Species diversity ,Geography ,Abundance (ecology) ,Statistics ,Alpha diversity ,Prosperity ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,Global biodiversity ,media_common - Abstract
In order to develop a composite measure of community species diversity and abundance, a generalization of Morisita’s prosperity index is proposed. Using Hill’s diversity representation, the prosperity index is a product of the total number of individuals and the effective number of species in a community. A series of prosperity indices can be derived using a parameter (Hill’s number). As an analogy of component partitions of species diversity, regional, within, and between components are also defined. The prosperity index will be useful for practical aspects related to conservation and management. more...
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- 2015
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10. Effects of environmental factors on the density of three species of peracarid crustaceans in micro-tidal sandy shores in Japan
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Takuhiko Murakami, Yoshitake Takada, Naoto Kajihara, and Shota Mochizuki
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Shore ,geography ,Functional ecology ,geography.geographical_feature_category ,Habitat ,Ecology ,Abundance (ecology) ,Environmental science ,Submarine pipeline ,Ecology, Evolution, Behavior and Systematics ,Coastal erosion ,Swash ,Trophic level - Abstract
The swash zone of sandy shores is a transitional habitat between the sea and land where the physical environment is the primary factor influencing the distribution of shore macrofauna. We constructed cumulative logit models using Bayesian inference to predict the ranked abundance of three species of peracarid crustaceans (Haustorioides japonicus, Excirolana chiltoni, and Archaeomysis kokuboi) that dominate the sandy shores of the Niigata coastline, Sea of Japan. Additionally, we estimated the importance of 14 environmental factors at explaining the variation in abundance. The environmental factors were grouped into three categories: swash zone, landward, and offshore. Optimum models were selected among the null model, the basic model (swash zone factors only), and additional models with landward and/or offshore factors. The optimal model for each of the three species was obtained when landward and/or offshore factors were added to the basic model, suggesting the importance of these regional factors. Combinations of significant factors differed between the three peracarid species. Some differences can be explained by accounting for life history characteristics. The slope of the offshore seafloor was the only common significant factor for the three species. Therefore, a decrease in the size of the shallow area off the sandy shore was associated with a decrease in the density of the three species. Because the peracarid crustaceans play an important role in trophic links in sandy shore ecosystems, our study results predict that an increase of coastal erosion leading to change of near-shore bathymetry will reduce the ecological function of the swash zone. more...
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- 2014
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11. Growth of the coconut crab Birgus latro estimated from mark-recapture using passive integrated transponder (PIT) tags
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Shigeki Dan, Osamu Abe, Takuro Shibuno, Yoshitake Takada, Kenzo Yoseda, Taku Sato, and Katuyuki Hamasaki
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Growth coefficient ,Ecology ,QH301-705.5 ,Field data ,food and beverages ,Zoology ,Aquatic Science ,Biology ,Oceanography ,biology.organism_classification ,Microbiology ,QR1-502 ,Mark and recapture ,Coconut crab ,Overexploitation ,Dry season ,Biology (General) ,Ecology, Evolution, Behavior and Systematics - Abstract
Determination of the growth pattern of a harvested species is an important step toward a proper assessment and suitable management of the stock. Although coconut crab Birgus latro populations in most regions have been severely depleted, few reliable biological data are available. We assessed the growth of B. latro using a mark-recapture method based on the use of passive integrated transponder (PIT) tags on Hatoma Island, located southwest of Okinawa, Japan. Of 781 crabs tagged (337 males, 444 females; 14.89 to 58.03 mm thoracic length (ThL)), 17 males and 20 females were recaptured. The application of PIT tags provided field data for growth of individuals for up to 2326 d and confirmed that coconut crabs molt during the winter dry season on Hatoma Island. The curves relating ThL with age, estimated from data of 29 crabs that had spent one or multiple winter dry seasons at liberty, showed that the coconut crab is an extremely slow growing species, with males showing much higher mean asymptotic ThL (69.87 mm) than females (42.79 mm). The Brody growth coefficient (K)was 0.061 yr �1 for males and 0.091 yr �1 for females. This study is the first to provide growth estimates of wild coconut crabs based on mark- recapture over multiple years. Potentially long-lived, slow growing species such as coconut crabs may be susceptible to overharvesting, and a cautious approach is recommended to the determina- tion of resource management regimes for B. latro. more...
- Published
- 2013
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12. QTL affecting fitness of hybrids between wild and cultivated soybeans in experimental fields
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Norihiko Tomooka, Duncan A. Vaughan, Yoshitake Takada, Akito Kaga, Shin Kato, Yosuke Kuroda, and Hiroshi Yano
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Glycine soja × G. max ,education.field_of_study ,Ecology ,QTL ,Population ,introgression ,Seed dormancy ,food and beverages ,Introgression ,Biology ,Quantitative trait locus ,biology.organism_classification ,Horticulture ,Fitness ,Botany ,Allele ,Glycine soja ,education ,Inbreeding ,Ecology, Evolution, Behavior and Systematics ,Original Research ,Nature and Landscape Conservation ,Hybrid - Abstract
The objective of this study was to identify quantitative trait loci (QTL) affecting fitness of hybrids between wild soybean (Glycine soja) and cultivated soybean (Glycine max). Seed dormancy and seed number, both of which are important for fitness, were evaluated by testing artificial hybrids of G. soja × G. max in a multiple-site field trial. Generally, the fitness of the F1 hybrids and hybrid derivatives from self-pollination was lower than that of G. soja due to loss of seed dormancy, whereas the fitness of hybrid derivatives with higher proportions of G. soja genetic background was comparable with that of G. soja. These differences were genetically dissected into QTL for each population. Three QTLs for seed dormancy and one QTL for total seed number were detected in the F2 progenies of two diverse cross combinations. At those four QTLs, the G. max alleles reduced seed number and severely reduced seed survival during the winter, suggesting that major genes acquired during soybean adaptation to cultivation have a selective disadvantage in natural habitats. In progenies with a higher proportion of G. soja genetic background, the genetic effects of the G. max alleles were not expressed as phenotypes because the G. soja alleles were dominant over the G. max alleles. Considering the highly inbreeding nature of these species, most hybrid derivatives would disappear quickly in early self-pollinating generations in natural habitats because of the low fitness of plants carrying G. max alleles. more...
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- 2013
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13. Effects of sediment hardness on the upper limit of the distribution of the burrowing amphipod Haustorioides japonicus on sandy shores: a field evaluation
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Yoshitake Takada, Naoto Kajihara, and Shinji Sassa
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Shore ,Haustorioides japonicus ,geography ,geography.geographical_feature_category ,Oceanography ,Ecology ,Sediment ,Aquatic Science ,Ecology, Evolution, Behavior and Systematics ,Geology - Published
- 2013
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14. Spatial variation in population dynamics of the sand‐burrowing amphipod Haustorioides japonicus
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Kazunori Yamahira, Yoshitake Takada, Naoto Kajihara, and Yuya Suzuki
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Shore ,education.field_of_study ,geography ,geography.geographical_feature_category ,Ecology ,fungi ,Population ,Biology ,Plankton ,Fecundity ,Salinity ,Productivity (ecology) ,Biological dispersal ,Spatial variability ,education ,human activities ,geographic locations ,Ecology, Evolution, Behavior and Systematics - Abstract
Densities of sandy beach organisms along coastlines often vary considerably even within small local scales. In order to understand the demographic basis of density variations in shore animals, we examined the population dynamics of the amphipod Haustorioides japonicus Kamihira, which is an ideal subject because it lacks a planktonic dispersal stage in its life history. Quantitative sampling at three adjacent sandy beaches along the Sea of Japan coast revealed that the spring density, i.e., the density of overwintered individuals, was similar among the three beaches. However, the amount of recruitment of newly hatched juveniles from late spring to summer greatly differed among the beaches, resulting in large spatial variations in the summer density. Cohort analyses revealed that at all beaches, young-of-the-year (YOY) individuals reproduced and then died, and that individuals which recruited in late summer overwintered. Moreover, growth, fecundity, and survival schedules of overwintered and YOY individuals were very similar among beaches. These observations suggest that the difference in recruitment success, i.e., the survival of newly hatched juveniles, is the primary cause of the inter-population variation in the summer density. It is likely that variations in salinity and sandy sediment affect the recruitment success of newly hatched individuals. This study indicates that biological productivity may differ substantially even among adjacent sandy beaches, with important implications for beach management. more...
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- 2012
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15. Colonization patterns of mobile cryptic animals into interstices of coral rubble
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Yoshitake Takada, Takuro Shibuno, and O. Abe
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geography ,geography.geographical_feature_category ,Ecology ,Coral ,Rubble ,Coral reef ,Aquatic Science ,engineering.material ,Biology ,biology.organism_classification ,Oceanography ,Seagrass ,Productivity (ecology) ,Habitat ,engineering ,Colonization ,Reef ,Ecology, Evolution, Behavior and Systematics - Abstract
Coral rubble is one of the characteristic bottom habitats in tropical and subtropical coral reefs. Many mobile organisms inhabit the interstices among coral rubble. Because coral rubble habi- tats are frequently subjected to physical disturbances, the process of assemblage recolonization is important for maintaining the diversity and productivity in coral reefs. The present study examined the colonization patterns of these mobile organisms by using experimental traps with defaunated coral rubble at 3 areas (Back reef, Seagrass bed, and Nearshore) in a fringing coral reef on Ishigaki Island, Japan. Sixteen mesh trays filled with coral rubble were set at each of the 3 areas; 4 trays were collected after 1, 2, 4, and 8 wk. The experiment was repeated in winter and spring. The number of species that occurred in the trays generally increased with the time period, but detailed examination was difficult because of significant interaction factors. Higher order interactions (season, area, and time period) were also significant for variations in assemblage composition. Temporal and spatial variations in abundances of 15 numerically dominant species (gastropods and decapods) were analyzed by a general linear model with an Akaike's information criterion model selection. Although the patterns of colonization were species specific, initial ( more...
- Published
- 2007
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16. A New Species of the Hermit Crab Genus Pagurixus (Crustacea: Decapoda: Anomura: Paguridae) from Shallow Coral Reefs of Ishigaki Island, Ryukyu Islands
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Tomoyuki Komai and Yoshitake Takada
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Anomura ,geography.geographical_feature_category ,biology ,Decapoda ,Ecology ,Coral reef ,biology.organism_classification ,Hermit crab ,Paguridae ,Crustacean ,Fishery ,Geography ,Genus ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics - Published
- 2006
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17. Dimorphic migration, growth, and fecundity in a seasonally split population of Littorina brevicula (Mollusca: Gastropoda) on a boulder shore
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Yoshitake Takada
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education.field_of_study ,biology ,Ecology ,Littorina brevicula ,fungi ,Population ,Littorina ,Intertidal zone ,Fecundity ,biology.organism_classification ,Mark and recapture ,parasitic diseases ,Gastropoda ,education ,Mollusca ,Ecology, Evolution, Behavior and Systematics - Abstract
Littorina brevicula (Philippi) is an abundant herbivorous gastropod species inhabiting intertidal zones of the north-western Pacific and has internal fertilization with planktonic eggs and a larval stage. A population of L. brevicula on a shore in Amakusa, Japan, splits into an upper and a mid shore sub-population during the mating season in winter, while all individuals occurred in the upper zone in summer. Transplant and recapture experiments have shown that snails from each sub-population have a distinct pattern of seasonal migration, suggesting that the snail population consists of two behavioral morphs. To explore the relationship between migration pattern and life history characteristics in the snails of the two migration morphs, monthly quantitative samplings and a mark-release and recapture survey were carried out for the population of L. brevicula over a 1-year period. In autumn, some of the adults migrated downward to the mid shore and formed the lower sub-population from October to April. Migration between the upper and lower sub-populations was minimal from December to February, when L. brevicula copulate actively. The shell growth rates of the snails in the lower zone were slightly higher than those in the upper zone, but the shell width of females was not a good predictor of the number of mature ova they contained. The number of mature ova was not significantly different between the females of the two migration morphs. In addition, the mortality of marked snails did not differ significantly between the upper and lower zones. Thus, no evidence was obtained to indicate a difference in the reproductive fitness between the two migration morphs. more...
- Published
- 2003
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18. Influence of shade and number of boulder layers on mobile organisms on a warm temperate boulder shore
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Yoshitake Takada
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Shore ,geography ,geography.geographical_feature_category ,Ecology ,Monodonta labio ,Hemigrapsus sanguineus ,Intertidal zone ,Species diversity ,Aquatic Science ,Biology ,biology.organism_classification ,Population density ,Light intensity ,Oceanography ,Habitat ,Ecology, Evolution, Behavior and Systematics - Abstract
The environment of the habitat is important in the organization of the intertidal community. In a boulder shore habitat, accumulation of boulder layers increases shade and the number of interstices. This study examined whether experimental shade increased the density of mobile animals and modified the community structure at 2 intertidal zones on a moderately sheltered boulder shore in Amakusa, Japan. Artificial shade reduced light intensity and surface temperature of boulders, and subsequently increased microalgal abundance. Mobile animals were sampled quantitatively at 2 zones (high and mid) for 4 treatments: single layer boulders without a roof as a control, double layer boulders without a roof, single layer boulders shaded by a roof for 6 wk and for 2 wk. Statistical analyses (MANOVA and ANOVA) showed strong effects of treatments on community diversity and the density of 15 abundant species in both tidal zones. Generally, the diversity was lower in the single layer boulders than the double layer boulders and increased with the experimental shade. Two carnivorous species (Hemigrapsus sanguineus and Japeuthria cingulata) and some herbivorous species (e.g. Nerita japonica and Nipponacmea nigrans) increased in density with the shade, while other herbivores (e.g. Monodonta labio and Littorina brevicula) were unaffected. In conclusion, a reduction of environmental stress produced by the shade increased community diversity on the boulder shore, but the responses of mobile animals were species specific. As these responses to a change in the environment occurred within a very short period (< 2 wk), migration may play an important role in the short-term variation of community structure on boulder shores. more...
- Published
- 1999
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19. Vertical variation in fecundity of the intertidal gastropod Monodonta labio caused by different growth rates between tidal zones
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Yoshitake Takada
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0106 biological sciences ,education.field_of_study ,biology ,Ecology ,Monodonta labio ,Trochidae ,Population ,Intertidal zone ,biology.organism_classification ,Fecundity ,010603 evolutionary biology ,01 natural sciences ,Spawn (biology) ,Oceanography ,Gastropoda ,Monodonta ,education ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany - Abstract
Monodonta labio (Gastropoda: Trochidae) occurs in a wide tidal zone on a boulder-covered shore in Amakusa, Japan. To investigate sources of variation in reproductive output within a population, the fecundity ofM. labio was estimated. Regressions of gonad egg counts on shell width were calculated from samples collected bi-weekly at three tidal zones: high, mid and low intertidal. Seasonal fluctuations in the regression revealed that individual females spawn at least three times a year. Variation in fecundity between the three tidal zones was not detected at any time in standard 12 mm snails. Due to the high growth rate in the low zone during the reproductive season, annual fecundity in the low zone was larger than that in the high and mid zones. Thus, tidal zone variation in fecundity ofM. labio was a result of growth variation between tidal zones. more...
- Published
- 1996
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20. Variation of growth rate with tidal level in the gastropod Monodonta labio on a boulder shore
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Yoshitake Takada
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Shore ,geography ,geography.geographical_feature_category ,Ecology ,biology ,Monodonta labio ,Trochidae ,fungi ,Aquatic Science ,biology.organism_classification ,Animal science ,parasitic diseases ,Gastropoda ,Environmental science ,Monodonta ,Growth rate ,Quadrat ,Diel vertical migration ,Ecology, Evolution, Behavior and Systematics - Abstract
Growth of Monodonta lablo (Linne) (Gastropoda: Trochidae) was investigated bimonthly for a period of 1 yr by quadrat sampling and mark-recapture on a moderately exposed boulder shore in Amakusa, South Japan. Linear regression was calculated for shell width at recapture on shell width at release. Growth in the high zone was slower than in the mid and low zones and decreased as shell width increased. Estimated growth curves fit well with the observed growth curves of individual snails. Seasonal growth patterns of juvenile (58 mm) snails may be affected by seasonal fluctuation of micro- algal abundance. Due to reproduction, growth of large snails decreased in summer. Tidal level varia- tion of growth rate caused large variation in growth curves in middle-sized snails (ca 10 rnm shell width), because of their wide range of distribution, which was related to vertical migration on the shore. Simulated growth curves showed that 8 mm snails in the high zone reached asymptotic size (ca 13 mm) 1 yr later than snails in the mid and low zones. In small (ca 6 mm) and large (ca 13 mm) snails, less van- ability in observed growth curves was explained due to their limited ranges of distribution. This study demonstrates that variation in growth rate is attributable to sue-specific distribution on a shore and indicates how migration expands size variation within a single age group. more...
- Published
- 1995
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21. Contrasting characteristics in increasing and decreasing phases of the Nerita japonica (Mollusca: Gastropoda) population on a boulder shore
- Author
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Yoshitake Takada
- Subjects
Shore ,education.field_of_study ,geography ,geography.geographical_feature_category ,biology ,Ecology ,Range (biology) ,Population ,Intertidal zone ,biology.organism_classification ,Japonica ,Nerita japonica ,Animal science ,Gastropoda ,Quadrat ,education ,Ecology, Evolution, Behavior and Systematics - Abstract
The present study demonstrated the seasonal and annual fluctuations in population characteristics of Nerita japonica on a boulder shore at Amakusa, Japan, and examined key characteristics in the increasing and decreasing phases for population monitoring. Monthly quantitative quadrat sampling and subsequent mark-recapture experiments were carried out during two periods: from April 1989 to July 1990 (1st period), and from August 1991 to November 1992 (2nd period). The density of the population was in a decreasing phase during the 1st period and in an increasing phase during the 2nd period. The density increase coincided with the extension of the vertical distribution range to a lower tide level, increase in the number of recruitment events, increase in the proportion of juveniles within the population, and increase in the survival of juveniles and adults. The growth rate was slightly increased but the average shell length of adult cohorts did not show any change. Additional observations showed a continued density increase and range extension until 1994. On the other hand, the density decrease coincided with recruitment failure and a low rate of survival with an unchanged range of the vertical distribution. Thus, for monitoring the population of N. japonica, recruitment success and changes in density and distribution range are key characteristics, but the shell size is not. These findings show the potential usefulness of N. japonica as an indicator of the shore environment. more...
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22. Role of suction in sandy beach habitats and the distributions of three amphipod and isopod species
- Author
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Yoshitake Takada, Soonbo Yang, Shinji Sassa, Yoichi Watabe, and Naoto Kajihara
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Geophysical Processes ,Haustorioides japonicus ,Suction ,Soil test ,Ecology ,Sandy beach habitats ,Physiology ,Ecology (disciplines) ,Japan Sea ,Intertidal zone ,Sediment compaction ,Biology ,Aquatic Science ,Oceanography ,Species distributions ,Habitat ,Burrowing ,Ecology, Evolution, Behavior and Systematics - Abstract
Sandy beach ecology has progressed rapidly with the emergence of several theories developed on the basis of understanding of hydrodynamic and morphodynamic processes on sandy beach habitats. However, the possible role of dynamic geophysical processes in the sediments remains poorly understood. The present study aims to explore the role of such geophysical processes in the sediments in forming the habitat environment and how they influence the species distributions. We conducted sets of integrated observations and surveys on intertidal and supratidal geophysical environments and the distributions of three amphipod and isopod species at four exposed sandy beaches located on the Japan Sea coast of Niigata Prefecture, Japan. The field results combined with a series of laboratory soil tests demonstrate that suction governed the variability of habitat environments observed, involving the degree of saturation, density, and hardness of the cross-shore intertidal and supratidal sediments, depending on the severity of the suction-dynamics-induced sediment compaction. While the observed species abundances were consistent with existing theories relating to intertidal and supratidal species, the observed magnitudes of suction were responsible for the distribution limits of the amphipods Haustorioides japonicus and Talorchestia brito and the isopod Excirolana chiltoni manifested consistently throughout the different beaches. The results of controlled laboratory experiments and field tests further revealed three distinctive suction-induced mechanisms, associated with their burrowing and physiology and the stability of the burrows. The novel role of such suction-induced geophysical processes in forming the habitat environment and influencing the species distributions may advance our understanding of sandy beach ecology in intertidal and supratidal zones. more...
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