The population of the ferrugineous limpet (<em>Patella ferruginea</em>), a species in... more The population of the ferrugineous limpet (<em>Patella ferruginea</em>), a species in risk of extinction, is evaluated in the whole littoral of the Autonomous City of Melilla (Spain) by sampling done between March and June, 2010. Moreover, detailed censuses were performed in eight transects distributed along the coastline. Results allow to estimate a total population of 32,821 adult specimens (shell maximum diameter larger than 30 mm). The population shows a well structured size/age distribution, with a wide range of sizes from young to large individuals, but specimens larger than 90 mm are scarce. <em>Patella ferruginea </em>is distributed in Melilla both on the natural rocky shores and on the numerous artificial structures which constitute more than a half of the littoral. It should be pointed out its abundance on the external breakwater of the Melilla port, where is concentrated the 68.1% of the estimated population. The average density of adults for the w...
Several samples of bioclastic sediment collected by scuba diving at various depths in the sourrou... more Several samples of bioclastic sediment collected by scuba diving at various depths in the sourrounding bottoms of the Chafarinas Islands (SW Mediterranean) have been studied. As a result, a total of 382 species of gastropods were recorded. Families which include a higher number of species were Pyramidellidae (55), Rissoidae (32), Cerithiopsidae (21), Trochidae (20), Mangeliidae (17) and Eulimidae (15). Some taxonomic comments are given on species of the families Cerithiopsidae, Eulimidae and Pyramidellidae and on the genera Alvania, Ocinebrina and Cima.
ABSTRACT Achieving to obtain juveniles of the limpet Patella ferruginea has been considered as on... more ABSTRACT Achieving to obtain juveniles of the limpet Patella ferruginea has been considered as one on the best possibilities for the recovery of this critically endangered Mediterranean species. Here we present results of two different and complementary strategies developed with this purpose. Results obtained during last two years are presented and evaluated from different points of view, particularly in relation with viability for its practical and immediate use in conservation issues of the species.
ABSTRACT We report on a study of reproduction and development in the Mediterranean vermetid gastr... more ABSTRACT We report on a study of reproduction and development in the Mediterranean vermetid gastropod Vermetus triquetrus from the SE coast of Spain. It is a gonochoristic species. The egg capsules are attached to the inside of the shell, and females brood up to 22 capsules simultaneously (more often 4–10). The capsules hold 10–61 eggs or embryos; the uncleaved eggs are yolk-rich, with a mean diameter of 377.3 μm. A distinct polar lobe occurs during the first cleavage, and blastomere D has discernible qualities after the 4-cell stage. The formation of the mesentoblast 4d occurs at the transition from the 24-cell stage to the 25-cell stage. Gastrulation begins after the 36-cell stage. Internal yolk is the major source of nutrition for the encapsulated embryos, but some nurse eggs (∼ 12%) and some sibling larvae are also ingested by the developing embryos. Hatching occurs during the swimming/crawling pediveliger stage, and metamorphosis is completed outside the capsules soon after hatching. Hence, larval development in Vermetus triquetrus is lecithotrophic intracapsular, with a short free-swimming/crawling phase.
Journal of the Marine Biological Association of the United Kingdom, 1998
The reproductive biology of the gregarious Mediterranean vermetid gastropod Dendropoma petraeum (... more The reproductive biology of the gregarious Mediterranean vermetid gastropod Dendropoma petraeum (Mollusca: Gastropoda) has been studied in the south-eastern coast of Spain. It apparently is a gonochorisric species with the sex ratio biased toward females (71%). A broad peak of more intense reproductive activity occurs in spring months and an inactive reproductive period during winter. The gonad of the males develops about two months before those of females, and storage of sperm by females has been observed. Internal fertilization takes place after the capture of pelagic spermatophores.The egg capsules lie free within the female mantle cavity, and females brood up to 86 capsules simultaneously (the highest number reported for any vermetid gastropod). The size of the capsules is somewhat variable and increases slightly from those containing first stages of development (mean = 678×579 μm) to those containing late stages (mean = 996×693 μm). Each egg capsule usually contains a single la...
The population of the ferrugineous limpet (<em>Patella ferruginea</em>), a species in... more The population of the ferrugineous limpet (<em>Patella ferruginea</em>), a species in risk of extinction, is evaluated in the whole littoral of the Autonomous City of Melilla (Spain) by sampling done between March and June, 2010. Moreover, detailed censuses were performed in eight transects distributed along the coastline. Results allow to estimate a total population of 32,821 adult specimens (shell maximum diameter larger than 30 mm). The population shows a well structured size/age distribution, with a wide range of sizes from young to large individuals, but specimens larger than 90 mm are scarce. <em>Patella ferruginea </em>is distributed in Melilla both on the natural rocky shores and on the numerous artificial structures which constitute more than a half of the littoral. It should be pointed out its abundance on the external breakwater of the Melilla port, where is concentrated the 68.1% of the estimated population. The average density of adults for the w...
Several samples of bioclastic sediment collected by scuba diving at various depths in the sourrou... more Several samples of bioclastic sediment collected by scuba diving at various depths in the sourrounding bottoms of the Chafarinas Islands (SW Mediterranean) have been studied. As a result, a total of 382 species of gastropods were recorded. Families which include a higher number of species were Pyramidellidae (55), Rissoidae (32), Cerithiopsidae (21), Trochidae (20), Mangeliidae (17) and Eulimidae (15). Some taxonomic comments are given on species of the families Cerithiopsidae, Eulimidae and Pyramidellidae and on the genera Alvania, Ocinebrina and Cima.
ABSTRACT Achieving to obtain juveniles of the limpet Patella ferruginea has been considered as on... more ABSTRACT Achieving to obtain juveniles of the limpet Patella ferruginea has been considered as one on the best possibilities for the recovery of this critically endangered Mediterranean species. Here we present results of two different and complementary strategies developed with this purpose. Results obtained during last two years are presented and evaluated from different points of view, particularly in relation with viability for its practical and immediate use in conservation issues of the species.
ABSTRACT We report on a study of reproduction and development in the Mediterranean vermetid gastr... more ABSTRACT We report on a study of reproduction and development in the Mediterranean vermetid gastropod Vermetus triquetrus from the SE coast of Spain. It is a gonochoristic species. The egg capsules are attached to the inside of the shell, and females brood up to 22 capsules simultaneously (more often 4–10). The capsules hold 10–61 eggs or embryos; the uncleaved eggs are yolk-rich, with a mean diameter of 377.3 μm. A distinct polar lobe occurs during the first cleavage, and blastomere D has discernible qualities after the 4-cell stage. The formation of the mesentoblast 4d occurs at the transition from the 24-cell stage to the 25-cell stage. Gastrulation begins after the 36-cell stage. Internal yolk is the major source of nutrition for the encapsulated embryos, but some nurse eggs (∼ 12%) and some sibling larvae are also ingested by the developing embryos. Hatching occurs during the swimming/crawling pediveliger stage, and metamorphosis is completed outside the capsules soon after hatching. Hence, larval development in Vermetus triquetrus is lecithotrophic intracapsular, with a short free-swimming/crawling phase.
Journal of the Marine Biological Association of the United Kingdom, 1998
The reproductive biology of the gregarious Mediterranean vermetid gastropod Dendropoma petraeum (... more The reproductive biology of the gregarious Mediterranean vermetid gastropod Dendropoma petraeum (Mollusca: Gastropoda) has been studied in the south-eastern coast of Spain. It apparently is a gonochorisric species with the sex ratio biased toward females (71%). A broad peak of more intense reproductive activity occurs in spring months and an inactive reproductive period during winter. The gonad of the males develops about two months before those of females, and storage of sperm by females has been observed. Internal fertilization takes place after the capture of pelagic spermatophores.The egg capsules lie free within the female mantle cavity, and females brood up to 86 capsules simultaneously (the highest number reported for any vermetid gastropod). The size of the capsules is somewhat variable and increases slightly from those containing first stages of development (mean = 678×579 μm) to those containing late stages (mean = 996×693 μm). Each egg capsule usually contains a single la...
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