Turbinid Gastropod Research Articles

Shell drilling and gonad biopsies provide a rapid, nonlethal method for in situ assessment of reproductive periodicity in a turbinid gastropod

ABSTRACT Reproductive data on marine molluscs are imperative for informing conservation and management strategies. Most methods for assessing reproductive periodicity are lethal, which could be unfavourable for fragile populations. This study aimed to trial a nonlethal, drill-biopsy technique for assessing the reproductive cycle in the turbinid gastropod, Turbo militaris. This technique was tested in the laboratory, where a small hole was drilled into the shell, from where a biopsy of the gonad was taken. The procedures resulted in zero mortalities and rapid recovery of the animals when returned to seawater. Sex was identified by viewing the gonad colour through the shell hole and confirmed by viewing gametes from a biopsy. Preservation of the female biopsy was investigated, with buffered formalin found to be the most suitable solution. The drill-biopsy method was also tested in the field; five (out of six) recaptured T. militaris had repaired the shell hole after 6 weeks, and two were recaptured on multiple occasions up to the end of this study, 10 months later. The size–frequency distributions of oocytes from female biopsies suggested an increase in mode size over 2 months with a shift towards a higher number of larger oocytes, supporting the practicality of this nonlethal approach to evaluate reproductive periodicity and sex determination. Nonlethal sampling is recommended for broad-scale studies and populations under stress; methods, such as the drill-biopsy technique, facilitate reproductive sampling without detriment to the target populations.

Revision of Four Species of Turbo (Marmarostoma) (Gastropoda: Turbinidae) from the Lower-Middle Miocene of Japan

The turbinid gastropod species Turbo (Lunella) ozawai Otuka, 1938 was described based on two opercula from the lower to middle Miocene Korematsu Formation in Southwest Japan. This inadequate proposal of the new species without the shell character information has confused subsequent taxonomic and faunal studies on the early to middle Miocene species of Turbo in Japan. For the first time, we clarify the shell characters of T. (M.) ozawai based on the type series and newly obtained materials from the Korematsu Formation in the Shobara area, Hiroshima Prefecture, and the Yoshino Formation in the Tsuyama area, Okayama Prefecture, Southwest Japan. The clarification of the shell and opercular characters of T. (M.) ozawai has enabled a taxonomic revision of the previously described four nominal species from early to middle Miocene species of Turbo (Marmarostoma) from the Honshu Arc of the Japanese Islands. Consequently, these four species are reclassified into two species, T. (M.) ozawai and T. (M.) tochiyensis Kanno, 1958; T. (M.) parvuloides Nomura, 1940 and T. (M.) minoensis Itoigawa, 1960 are junior synonyms of T. (M.) ozawai and T. (M.) tochiyensis, respectively. Both species are rare examples of mollusks that thrived along the Honshu Arc throughout the Miocene Climatic Optimum (∼16.9 to 14.7 Ma). The species richness of Turbo (Marmarostoma) is similar to that of the modern species in the warm water region of the Japanese Islands.

An Additional New Species of Turbo (Marmarostoma) (Gastropoda: Turbinidae) from the Middle Miocene of the Izu Peninsula, Central Japan

The turbinid gastropod Turbo (Marmarostoma) is common in the limestone bodies within the middle Miocene Sakurada and Kadono formations (Yugashima Group) on the Izu Peninsula, central Japan. The limestone bodies were originally deposited under a low-latitude, tropical climate in the northeastern Philippine Sea and then drifted northwards on the Philippine Sea Plate. This paper describes an additional species, Turbo (Marmarostoma) ishidai sp. nov., from the Ena Limestone on the south-western Izu Peninsula. This new species is characterized by its large shell size and shell form similar to the modern Australian endemic species Turbo (Marmarostoma) cepoides Smith, 1880, but differs in having thick tuberculate spiral cords on the shell surface of earlier teleoconch whorls instead of the smooth and broad spiral cords on and around the angled shoulder. The addition of this new species further highlights the presence of a biodiversity hotspot of this gastropod group in the northeastern Philippines Sea during the middle Miocene.

腹足類(リュウテンサザエ科)の石灰化蓋の構築構造

腹足類(リュウテンサザエ科)の石灰化蓋の構築構造

New species of the copepod genus Anthessius Della Valle, 1880 (Poecilostomatoida: Anthessiidae) from Turbo marmoratus Linnaeus (Gastropoda: Turbinidae) collected during the KUMEJIMA 2009 Expedition

Anthessius isamusi n. sp. is described based on female and male specimens from a turbinid gastropod, Turbo marmoratusLinnaeus, collected in the East China Sea off Kumejima Island, the Ryukyu Islands, southern Japan, during the KUME-JIMA 2009 Expedition. The female of the new species is differentiated from its congeners by the following combinationof characters: 1) the absence of denticles on the ventral surface of the anal somite; 2) the length to width ratio of the caudalramus; 3) the antenna bearing 4 claws; 4) the maxilla with 3 distal teeth; 5) the exopod of leg 4 with 3 spines on the terminal segment, and; 6) leg 5 with a rod-like terminal segment.

Depletion of predatory fish by fishing in a ­temperate reef ecosystem leads to indirect effects on prey, but not to lower trophic levels

Indirect effects of fishing extending 2 or more trophic levels have been observed in a range of ecosystems, but they are not ubiquitously present, and identifying the circumstances in which they occur (or do not occur) is a key challenge for ecologists. We compared a fully protected sanctuary (no fishing allowed) with 2 other types of management zones (one in which all types of fish- ing were allowed and another in which only recreational line fishing was allowed) at Rottnest Island, Australia. We predicted that fishing would result in lower abundance of predatory fish in the 2 fished zones. We further predicted that, if indirect effects of fishing are important, there would be lower pre- dation on sea urchins and turbinid gastropods, higher abundance of these herbivorous invertebrates and lower biomass of macroalgae in both types of fished zones. The abundance of predatory fish and predation on the sea urchin Heliocidaris erythrogramma were higher in the sanctuary than in fished zones. Predation on the sea urchin Centrostephanus tenuispinus was higher and densities of H. ery- throgramma were lower in the sanctuary, but the magnitude of the difference in these measures (and, therefore, the results of statistical tests) was variable among years. However, predation on turbinid gastropods, densities of C. tenuispinus and turbinid gastropods, and the biomass of macroalgae did not differ significantly among management zones. The pattern of higher abundance of predatory fish and higher rates at which prey were consumed in the sanctuary provide evidence for the indirect effects of fishing on the abundance of H. erythrogramma. However, there was no evidence that these indirect effects extend to a second species of sea urchin, or to turbinid gastropods, and no evidence that the effects lead to broad changes in the state of the ecosystem.

Trophic effects of fishing southern rock lobster Jasus edwardsii shown by combined fatty acid and stable isotope analyses

The southern rock lobster Jasus edwardsii is a commercial species that has benefited from the complete protection offered by no-take reserves, with higher abundances and larger ani- mals recorded in reserves than in adjacent fished areas. What remains unclear is whether there is any change in the diet of lobsters in reserves, for example, as a result of increased intraspecific competi- tion for food. We used combined chemical tracers to examine the diet of lobsters in fished and reserve areas in 2 bioregions in eastern Tasmania. δ15N values of lobsters were richer in fished than in reserve areas, indicating that lobsters eat a greater proportion of food items from higher trophic levels in fished areas. Mixing models suggest that ascidians, sea urchins and the turbinid gastropod were all important food sources for lobsters, but the importance of these food items differed between biore- gions. This spatial variability may suggest thatthe small size of the reserve in one bioregion is inad- equate at ensuring the diet of lobsters is protected from fishing pressure. Fatty acid profiles of lobsters supported the importance of these food sources to lobsters. Differences between bioregions, or inside and outside of reserves, were not apparent using fatty acids. The present study highlights that lobster fishing has the capacity to alter the trophic status of prey for generalist predators and suggests that fatty acid analyses may be limited in detecting changes in the dietary composition of such generalist feeders.

Population structure of turbinid gastropods on wave-exposed subtidal reefs: effects of density, body size and algae on grazing behaviour

Knowledge of the population structure and feeding capabilities of herbivores is critical to evaluate their influence on energy flow and community structure in their habitats. We tested for patterns in abundance (24 reefs) and size (12 reefs) of turbinid gastropods across 4 locations spanning >6° latitude (~1000 km) in Western Australia, and we tested the effect of density (1 to 5 individuals) and size (38.8 to 747.1 g wet wt) of Turbo torquatus on consumption of macroalgae with different thal- lus structure (Functional Groups 3 to 5). Turbinid gastropods were found at all locations (up to 2.4 ind. m -2 ); 82.4% of all individuals were T. torquatus. One location (Marmion, Perth) had considerably higher abundances than all other locations. Populations of T. torquatus at the 2 southern locations had a broad range of sizes (9 to 119 mm total shell length (TSL)), although 1 location was dominated by small, and the other, by large, individuals. In contrast, both northern locations were strongly dom- inated by 1 size class (40 to 60 mm TSL). T. torquatus consumed Ulva lactuca, Hypnea valentiae, Hennedya crispa and juvenile Ecklonia radiata at rates of 150 to 450 mg blotted fresh weight d -1 , depending on density of gastropods and species of algae. There was a positive relationship between the rate of consumption and size of T. torquatus when fed U. lactuca and H. valentiae. The present study has produced 3 main insights: (1) densities of turbinids on offshore, wave-exposed, subtidal reefs are similar to those in other coastal habitats; (2) patterns of abundances and sizes are consistent with broad-scale processes, such as ocean climate, fishing pressure and eutrophication; and (3) T. torquatus can consume a variety of macroalgae at rates that suggest it has the potential to exert top- down control of macroalgae, although low densities of gastropods preclude strong effects.

Bioactive volatile compounds from marine algae: feeding attractants

Chemical communications play an important role in plants, fungi, and algae. Volatile organic compounds in marine algae are released into the seawater. These compounds play a role as either pheromones or allelochemicals. We observed that the turbinid gastropod Lunella coronata coreensis inhabits the intertidal zone and often grazes the green alga Ulva pertusa. Feeding tests and feeding preference studies were performed with green, brown and red algae or by using the powdered freeze-dried seaweed in agar. The snails fed on U. pertusa preferentially compared to the other marine algae, and recognized chemoreception compounds from the alga but not their structural or morphological differences. From feeding tests using artificial foods, it is suggested that the feeding attractants are in the essential oil of the alga U. pertusa.

Predation and the geography of opercular thickness in turbinid gastropods

The heavily calcified opercula of turban snails (Turbinidae) function as passive-defensive structures against predators that break the shell at the outer lip or that enter the shell by way of the aperture. Passive armour generally is more common and much better developed in the tropics than in colder regions. In line with this expectation, the relative opercular thickness of tropical turbinids (mean 0.358 + 0.045, 33 species) significantly exceeds that of temperate species (mean 0.300 + 0.051, 21 species). Small differences in relative opercular thickness occur among tropical biogeographic regions, but none is significant. Patterns observed among turbinids as a whole also appear in individual clades, indicating that the patterns are not dictated by a phylogenetic signal.

Population dynamics and potential yield of three species of giant winkles in the Western Cape, South Africa

Of the southern African intertidal and shallow subtidal trochid and turbinid gastropods, Turbo sarmaticus , T. cidaris and Oxystele sinensis , are the most abundant large species, and therefore obvious targets for a winkle fishery. T. sarmaticus is harvested by recreational snorkel divers, and an application has been made for a permit to experimentally harvest the other two species commercially. This study involves four major aspects, namely morphometrics and flesh yield, shore-based abundance estimates, subtidal abundance estimates, and an estimate of the potential yield for each of the three species off the South-Western Cape, South Africa. Abundance and biomass of the winkles increased from west to east, highest densities being recorded in the low intertidal regions to 2 m depth. Low biomasses of the three species were recorded west of Cape Hangklip and are unlikely to support a fishery there. East of Cape Hangklip, invasion of rock lobsters Jasus lalandii has had a considerable impact on T. cidaris and O. sinensis populations. Consequently, a boat-based fishery with an estimated annual total allowable catch of 75.5 tons for T. cidaris , with a bycatch of 9.9 tons for O. sinensis , can only be considered in the easternmost fisheries-management area between Kleinbaai and Quoin Point. Because previous studies on the harvesting potential of T. sarmaticus off the Western Cape concluded that it was not commercially sustainable, a total allowable catch for that species was not considered. Management options deserving considerations before the commencement of a giant winkle fishery are discussed. Keywords: commercial exploitation, Oxystele sinensis , stock assessment, Turbo cidaris , Turbo sarmaticus , yield African Journal of Marine Science 2002, 24: 161–183

A New Turbinid Gastropod Collected from the Warm Seep Site in the Minami-Ensei Knoll, West of the Amami-Oshima Island, Japan

A New Turbinid Gastropod Collected from the Warm Seep Site in the Minami-Ensei Knoll, West of the Amami-Oshima Island, Japan

Interactions amongst species in a guild of subtidal benthic herbivores.

The subtidal coralline flats of northeastern New Zealand support a characteristic guild of grazing herbivores. The most important members of this guild are an echinometrid echinoid, patellid, turbinid and trochid gastropods. Densities of these herbivores fluctuate through time. Interactions within and among the different species of echinoids and gastropods were investigated experimentally. Different combinations of species were caged at densities up to 5 times that of ambient for a 24 week period in an experiment designed to differentiate between intra- and interspecific competition.The echinoidEvechinus chloroticus and the turbinid gastropodCookia sulcata exhibited reduced mean dry weight with increasing intraspecific densities. There was little evidence of density-related mortality in these species. The limpetCellana stellifera showed comparatively large losses of weight and enhanced mortalities in intraspecific experimental treatments but this was not related to density.Investigation of interspecific interactions amongstEvechinus andCookia revealed no evidence of a negative influence of one species on the other. In terms of dry weight,Cookia was indifferent to the presence ofEvechinus, andEvechinus benefited in the reciprocal interaction.Cookia also enjoyed an enhanced mean dry weight when in the presence ofCellana compared to the equivalent intraspecific treatments. There were no coherent trends in proportional mortality in any treatments with enhanced interspecific densities. Cellana, in the presence ofCookia, exhibited a dramatic decrease in mortality rate and increase in mean dry weight. The presence of the turbinid gastropod was clearly beneficial to the limpet when compared to the intraspecific treatments with enhanced intraspecific densities and the control cages containingCellana at ambient density. We suggest that subtidal areas constitute poor habitats for limpets in the absence of agents such asCookia which may provide or maintain suitable sites for attachment and grazing.For the combinations of densities and species investigated there was a consistent trend towards positive interspecific interactions. It seems unlikely that at the sites investigated interspecific competition could act to restrict distributions, or limit abundances of species.

Two New Turbinid Gastropods from the Philippines

Two New Turbinid Gastropods from the Philippines

Population variations in the grazing turbinidLunella smaragda(Mollusca: Gastropoda)

Abstract The grazing turbinid gastropod Lunella smaragda was sampled regularly over 3.5 y from precise sites of different microtopography and height on the platform shore at Goat Island Beach near Leigh, Northland, New Zealand. Growth is linear for over 3 y, and the year‐classes distinct. The position of the different size‐classes is related to both the shelter afforded by the microtopography, and to the height on the shore. The populations in the mid‐eulittoral turf flats, low eulittoral bare rock areas, and the sublittoral fringe are distinct, and there is a general movement down the shore with age and size. Wave action apparently dislodges the animals from higher areas when they grow to a critical size and transports them to sites lower on the shore, where wave disturbance is less. Field experiments with marked animals and laboratory studies with a wave tank confirm that the wave‐effected distribution is size related. However measurements showed that the ratio of foot attachment area to the shell area presented to the wave does not vary with animal size. The possible benefits of wave dislodgment and wave‐effected distribution are considered.

Rough water as a spawning stimulus in some Trochid and Turbinid gastropods

Abstract Adults of three species of common intertidal gastropods, Melagraphia aethiops, Zediloma atrovirens, and Lunella smaragda, were collected from Waitemata Harbour, Auckland (36° 51 S, 174° 47 E) and brought to the laboratory, where several methods of artificial spawning were attempted throughout the year. The one successful method, involving vigorous water movement around ripe adults, induced them to release gametes during their respective spawning seasons, and was equally effective in the natural habitat. Larval stages were found in the plankton only during periods of on‐shore wind speeds greater than 10 knots, with which their presence was correlated, rather than with tides, lunar cycles, or sea temperatures.