Microscale intertidal habitats modulate shell break resistance of the prey; Implications for prey selection.

Intertidal microhabitats provide special conditions to the organisms that inhabit them and to some of their morpho-protective characteristics. Tidal pools, under the influence of acidified freshwater, may affect the characteristics of the protective shells of prey and have repercussions on predation. The shells of Perumytilus purpuratus from such tidepools are more fragile than those of their counterparts from the vertical intertidal walls of the same area.

Understanding the Symbiotic Relationship between the Sea Urchin (Molina, 1782) and the Pea Crab (H. Milne Edwards, 1837): a Potential Parasitism.

The echinoderm has a symbiotic relationship with the pinnotherid crustacean . Females of the crustacean develop in the terminal section of the sea urchin's digestive system, remaining there for life. This relationship has been suggested as commensalism.

Body mass index does not decline during winter for the sedentary marine gastropod .

Seasonal extremes in environmental conditions can substantially limit the growth and reproduction of animals. Sedentary marine animals are particularly susceptible to winter food limitation since they cannot relocate to more favourable conditions. In several temperate-zone bivalve species, substantial winter tissue mass declines have been documented; however, no comparable studies have been conducted on intertidal gastropods.

The Marine Gastropod Remains Resilient to Ocean Acidification Across Two Life History Stages.

Rising atmospheric CO reduces seawater pH causing ocean acidification (OA). Understanding how resilient marine organisms respond to OA may help predict how community dynamics will shift as CO continues rising. The common slipper shell snail is a marine gastropod native to eastern North America that has been a successful invader along the western European coastline and elsewhere.

Impact of short-term elevated temperature stress on winter-acclimated individuals of the marine gastropod Crepidula fornicata.

The intertidal zone is an especially stressful thermal habitat, typically exposing residents to air temperatures for up to 6 h at a time, twice daily. Tolerance to elevated temperatures has been particularly well-studied for a variety of intertidal species, especially with regard to upper thermal limits during summers. However, in recent years, as climates have been changing around the world, temperate zone intertidal organisms have sometimes been exposed to periods of unusually high air temperatures during the winter.

Instant Ocean Natural Seawater: Impacts on Aspects of Reproduction and Development in Three Marine Invertebrates.

Marine invertebrate larvae have often been reared in artificial rather than natural seawater, either for convenience or to avoid potentially confounding effects of unknown contaminants. This study sought to determine the impact of artificial seawater on various aspects of development for three marine invertebrate species. We examined the impact of Instant Ocean on growth, survival, and fecundity of the deposit-feeding polychaete at 2 salinities: 24 and 34 ppt; the impact on survival, growth rate, and time to metamorphic competence for the slipper limpet ; and the impact on larval growth for the sea star .

Temperature and Salinity Effects on Shell Selection by the Hermit Crab Pagurus longicarpus.

The widespread coastal hermit crab Pagurus longicarpus relies on empty gastropod shells for shelter. At low tide, these hermit crabs often become stranded in tide pools, where changes in temperature and salinity can occur rapidly. We tested how changes in temperature and salinity affected the sizes of the shells chosen by hermit crabs.

Growing Safe: Acute Size Escape from Desiccation in Juvenile Crepipatella peruviana (Mollusca: Gastropoda).

Desiccation is an important limiting factor in the intertidal zone. Generally decreasing seaward, desiccation stress can also be alleviated in wet microhabitats. Juvenile snails are generally more susceptible to desiccation than adults, and, for some species, juveniles must therefore hide in microhabitats to survive emersion.

Effects of Embryonic Exposure to Salinity Stress or Hypoxia on Post-metamorphic Growth and Survival of the Polychaete Capitella teleta.

Although a good number of studies have investigated the impact of larval experience on aspects of post-metamorphic performance, only a few have considered the potential impact of stresses experienced by brooded embryos. In this study we separately investigated the impact of salinity stress (as low as 10) and hypoxia (1 ml O l) experienced by brooded embryos of the deposit-feeding polychaete Capitella teleta on hatching success, metamorphosis, post-metamorphic survival, and post-metamorphic growth. Salinity reduction from 30 to 10 or 15 reduced relative hatching success, presumably by reducing embryonic survival, but generally had no negative latent effects on juvenile survival or growth.

Role of the Substrate in Feeding and Growth of the Marine Suspension-Feeding Gastropods Crepidula fornicata and Crepipatella peruviana.

Unlike lamellibranch bivalves, suspension-feeding calyptraeid gastropods lack siphons and paired shell valves to regulate water inflow. This study was designed to determine if calyptraeid gastropods use the solid surface to which they attach to facilitate food particle capture. Juveniles of both Crepidula fornicata and Crepipatella peruviana were maintained with phytoplankton for 3 to 6 wk in the laboratory, either attached to solid substrate or without solid substrate.

Brooding strategy in fluctuating salinity environments: oxygen availability in the pallial cavity and metabolic stress in females and offspring in the Chilean oyster Ostrea chilensis.

Organisms that encounter stressful situations in nature often cope using behavioral (e.g., avoidance) or physiological tactics.

Brooding in the Chilean oyster Ostrea chilensis: unexpected complexity in the movements of brooded offspring within the mantle cavity.

Brooding in invertebrates serves to protect embryos from stressful external conditions by retaining progeny inside the female body, effectively reducing the risk of pelagic stages being exposed to predation or other environmental stressors, but with accompanying changes in pallial fluid characteristics, including reduced oxygen availability. Brooded embryos are usually immobile and often encapsulated, but in some Ostrea species the embryos move freely inside the female pallial cavity in close association with the mother's gills for as long as eight weeks. We used endoscopic techniques to characterize the circulation pattern of embryos brooded by females of the oyster, Ostrea chilensis.

The B vitamins nicotinamide (B3) and riboflavin (B2) stimulate metamorphosis in larvae of the deposit-feeding polychaete Capitella teleta: implications for a sensory ligand-gated ion channel.

Marine sediments can contain B vitamins, presumably incorporated from settled, decaying phytoplankton and microorganisms associated with decomposition. Because B vitamins may be advantageous for the energetically intensive processes of metamorphosis, post-metamorphic growth, and reproduction, we tested several B vitamins to determine if they would stimulate larvae of the deposit-feeding polychaete Capitella teleta to settle and metamorphose. Nicotinamide and riboflavin individually stimulated larvae of C.

Effects of low salinity on adult behavior and larval performance in the intertidal gastropod Crepipatella peruviana (Calyptraeidae).

Shallow-water coastal areas suffer frequent reductions in salinity due to heavy rains, potentially stressing the organisms found there, particularly the early stages of development (including pelagic larvae). Individual adults and newly hatched larvae of the gastropod Crepipatella peruviana were exposed to different levels of salinity stress (32(control), 25, 20 or 15), to quantify the immediate effects of exposure to low salinities on adult and larval behavior and on the physiological performance of the larvae. For adults we recorded the threshold salinity that initiates brood chamber isolation.

Paternity and gregariousness in the sex-changing sessile marine gastropod Crepidula convexa: comparison with other protandrous Crepidula species.

In sex-changing animals with internal fertilization, gregarious behavior may increase mating opportunities and the frequency of multiple paternity, thus increasing maternal reproductive success. Crepidula convexa is a direct-developing protandrous gastropod characterized by only modest gregarious behavior compared with previously studied members of the genus: females are frequently found isolated. Using 6 microsatellite markers, we analyzed paternity profiles in 10 broods (25 embryos per mother).

Understanding the effects of low salinity on fertilization success and early development in the sand dollar Echinarachnius parma.

Free-spawning marine invertebrates that live near shore or in estuaries may experience reduced fertilization success during low-salinity events. Although several studies have documented reproductive failure at reduced salinity in estuarine animals, few have looked at whether developmental failure is due to a failure of fertilization or to a failure of fertilized eggs to cleave. In this study, we examined the effects of salinities ranging from 18 to 32 psu on fertilization success and early development in the sand dollar Echinarachnius parma.

Fast versus slow larval growth in an invasive marine mollusc: does paternity matter?

Reproductive strategies and parental effects play a major role in shaping early life-history traits. Although polyandry is a common reproductive strategy, its role is still poorly documented in relation to paternal effects. Here, we used as a case study the invasive sessile marine gastropod Crepidula fornicata, a mollusc with polyandry and extreme larval growth variation among sibling larvae.

Nitric oxide inhibits metamorphosis in larvae of Crepidula fornicata, the slippershell snail.

This paper concerns the role of nitric oxide (NO) in controlling metamorphosis in the marine gastropod Crepidula fornicata. Metamorphosis was stimulated by the nitric oxide synthase (NOS) inhibitors AGH (aminoguanidine hemisulfate) and SMIS (S-methylisothiourea sulfate) at concentrations of about 100-1000 micromol l(-1) and 50-200 micromol l(-1), respectively. Metamorphosis was not, however, induced by the NOS inhibitor l-NAME (l-N(G)-nitroarginine methyl ester) at even the highest concentration tested, 500 micromol l(-1).

Effects of salinity on spawning and early development of the tube-building polychaete Hydroides elegans in Hong Kong: not just the sperm's fault?

Ambient salinities drop dramatically during monsoon season in Hong Kong coastal waters, posing a number of problems for externally fertilizing species like the polychaete Hydroides elegans. In this study, we investigated (1) whether adults would retain their gametes when external salinity dropped to levels too low to support fertilization and development, and (2) whether failure of development at low salinity reflects a failure of fertilization or a failure of fertilized eggs to cleave. Adults released eggs and sperm in the laboratory even at the lowest salinity tested, a practical salinity (S) of 5, and yet very few eggs cleaved at salinities below about 22.

Larval experience and latent effects--metamorphosis is not a new beginning.

For many years ecologists have documented the remarkable within-species variation inherent in natural systems-for example, variability in juvenile growth rates, mortality rates, fecundities, time to reproductive maturity, the outcomes of competitive interactions, and tolerance to pollutants. Over the past 20 years, it has become increasingly apparent that at least some of this variation may reflect differences in embryonic or larval experiences. Such experiences may include delayed metamorphosis, short term starvation, short term salinity stress, or exposure to sublethal concentrations of pollutants or sublethal levels of ultra violet irradiation.

Timing is everything: the effects of putative dopamine antagonists on metamorphosis vary with larval age and experimental duration in the prosobranch gastropod Crepidula fornicata.

The signal transduction pathway through which excess potassium ion stimulates the larvae of many marine invertebrates to metamorphose is incompletely understood. Recent evidence suggests that dopamine plays important roles in the metamorphic pathway of Crepidula fornicata. Therefore, we asked whether blocking dopamine receptors might prevent excess potassium ion from stimulating metamorphosis in this species.

THE ESCAPE OF VELIGERS FROM THE EGG CAPSULES OF NASSARIUS OBSOLETUS AND NASSARIUS TRIVITTATUS (GASTROPODA, PROSOBRANCHIA).

1. The loosening of the egg capsule plug prior to escape of the veligers is shown to be chemically mediated in Nassarius obsoletus and N. trivittatus.