Variability in the Reproductive Characteristics of Local Populations of an Intertidal Gastropod, Nerita japonica(Dunker)

Paruntu, Carolus P.; Tokeshi, Mutsunori

doi:10.5179/benthos1996.58.1_7

Cited by 7 publications

(13 citation statements)

References 30 publications

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“…Another type of benthic development has been reported in Nerita reticulata and N. japonica (Risbec, 1932;Paruntu and Tokeshi, 2003), although the details of their early ontogeny have not been elucidated. The egg capsules contain up to nine eggs.…”

Section: Nonplanktotrophic Developmentmentioning

confidence: 99%

“…Of the 29 operculate species studied, there is information in the literature about protoconch morphology for 14 species (Bandel, 1982;Bandel and Riedel, 1998;Sasaki, 1998;Kase, 2000, 2003;Warén and Bouchet, 2001;Paruntu and Tokeshi, 2003). All 29 species are newly investigated here in this context, and protoconch morphology is additionally documented for eight species (Table 2).…”

Section: Protoconchmentioning

confidence: 99%

“…A large supply of yolk in the ova seemingly makes the production of such a voluminous embryonic shell possible (Holthuis, 1995). The notable intraspecific variation in the size of their opercular nuclei (Table 2) and protoconchs may be explained by the supposition that variable amounts of food reserves define the sizes of the hatchlings in benthic species (Paruntu and Tokeshi, 2003; see also Hadfield and Iaea, 1989).…”

Section: Nonplanktotrophic Developmentmentioning

confidence: 99%

“…In contrast, the egg capsule of Nerita reticulata holds three to nine eggs, all of which develop into intracapsular veligers and hatch as large (ϳ750 m) crawl-away juveniles (Risbec, 1932). Nerita japonica, another species with benthic early development, appears to have a similar reproductive strategy: two to seven eggs in one capsule hatch as large (690 -810 m) juveniles (Paruntu and Tokeshi, 2003;Y. Kano, pers.…”

Section: Rearing Observationsmentioning

confidence: 99%

“…The early developmental mode of at least 36 neritimorph species has been studied in the laboratory (e.g., Risbec, 1932;Andrews, 1935;Bondesen, 1940;Scheltema, 1971;Govindan and Natarajan, 1972;Bandel, 1982;Holthuis, 1995;Kase, 2003, 2004;Paruntu and Tokeshi, 2003). Of these 36 species, four are benthic developers and hatch from egg capsules as large, crawl-away juveniles, while many others hatch as small, pelagic larvae.…”

Section: Rearing Observationsmentioning

confidence: 99%

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Usefulness of the opercular nucleus for inferring early development in neritimorph gastropods

Kano

2006

J. Morphol.

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The early ontogeny of gastropods (i.e., planktotrophic vs. nonplanktotrophic) may be inferable from the morphology of the protoconch in adult shells. The protoconch consists of both embryonic and larval shells in species with planktotrophic development; the embryonic shell forms in the intracapsular period and the succeeding larval shell gradually develops during the larval period. In nonplanktotrophic species, on the other hand, there is no additional growth of the larval shell and the protoconch consists exclusively of a relatively large embryonic shell formed prior to hatching. This "shell apex theory" has been applied to many species of shell-bearing gastropods, but biotic and abiotic erosion of the apex often prevents detailed examination of the protoconch and subsequent inferences about ontogeny. I examined the gastropod operculum to test its utility for predicting developmental mode, drawing on the Neritimorpha as model taxa. Most aquatic members of Neritimorpha were found to bear an operculum with a clearly demarcated nucleus; SEM observations reveal four types of nuclei, which correspond to different types of protoconch morphologies and observed ontogenies for the study species. The nucleus is secreted before metamorphosis, fits into the shell aperture of the larva, and reflects early ontogeny as morphology, as does the protoconch. Moreover, the apparently organic (rather than calcareous) composition of the nucleus makes it nearly invulnerable to erosion and very advantageous, compared to the protoconch, in this ecologically diverse group, whose habitats range from freshwater streams and mangrove swamps to rocky shores and deep-sea hydrothermal vents. The measurements of the nucleus are also valuable for taxonomic purposes, especially in the species identification of veliger larvae and juvenile snails. On the other hand, the opercular nuclei of the Caenogastropoda and Heterobranchia are often eroded away in adult individuals; even if present, the morphology of the nuclei does not seem to clearly reflect early ontogeny in those groups.

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Section: Nonplanktotrophic Developmentmentioning

confidence: 99%

Section: Protoconchmentioning

confidence: 99%

Section: Nonplanktotrophic Developmentmentioning

confidence: 99%

Section: Rearing Observationsmentioning

confidence: 99%

Section: Rearing Observationsmentioning

confidence: 99%

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Usefulness of the opercular nucleus for inferring early development in neritimorph gastropods

Kano

2006

J. Morphol.

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Testing scale variance in species–area and abundance–area relationships in a local assemblage: an example from a subtropical boulder shore

Londoño‐Cruz

Tokeshi

2007

Population Ecology

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Constancy or scale variance of species–area and abundance–area relationships has rarely been considered within relatively small spatial domains of a local assemblage. Patterns of species/abundance–area relationships were experimentally investigated in a stone‐associated molluscan community on a subtropical boulder shore. In order to systematically examine the effects of variation in habitat area while maintaining other habitat characteristics constant through time, naturally occurring stones were selected and divided into different size classes according to surface area and used as habitat units for regular monitoring of a mobile molluscan community. Species richness and abundance (number of individuals and biomass) of molluscs scaled with stone area, but the power or double‐logarithmic regression was not always the best description of the species–area relationship. Seasonal scale invariance was shown by the species–area relationship, whereas scale variance was clearly recognizable in the abundance–area relationships. The latter phenomenon was generated mainly by large stones contributing disproportionately to increases in molluscan abundance in particular. Furthermore, there was a negative effect of small habitat area whereby molluscan abundance was disproportionately reduced on small stones. Some temporal variation in the observed patterns was also recognizable, with higher species richness and abundance in spring than in winter, again with larger stones showing preponderant importance. This study thus demonstrates the significance of scale variance/invariance in species/abundance–area relationships, even within relatively small spatial scales of local habitat.

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Contrasting characteristics in increasing and decreasing phases of the Nerita japonica (Mollusca: Gastropoda) population on a boulder shore

Takada

2008

Population Ecology

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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.

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Variability in the Reproductive Characteristics of Local Populations of an Intertidal Gastropod, Nerita japonica(Dunker)

Cited by 7 publications

References 30 publications

Usefulness of the opercular nucleus for inferring early development in neritimorph gastropods

Usefulness of the opercular nucleus for inferring early development in neritimorph gastropods

Testing scale variance in species–area and abundance–area relationships in a local assemblage: an example from a subtropical boulder shore

Contrasting characteristics in increasing and decreasing phases of the Nerita japonica (Mollusca: Gastropoda) population on a boulder shore

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