The blue crab Callinectes sapidus Rathbun has been the subject of scientific investigation for more than 100 years. The crab is a key predator in shallow estuarine and coastal environments, and supports a large commercial fishery along the Atlantic and Gulf Coasts of the United States. Much of the initial research on C. sapidus was purely descriptive and provided only a patchwork perspective on the natural history of the crab. This is in contrast to more modern work that has defined a clear, interrelated series of processes that underlie the early life history of the species. The intent of the present review was to discuss contemporary understanding of the early life history of blue crabs in the context of a coherent time line of development. The review begins with a short section on general aspects of the life history, which provides a background for the overall discussion. This is followed by a segment on courtship and mating, with particular emphasis on chemical communication between mating pairs. Three subsequent sections then deal, respectively, with spawning migrations within the estuary, larval release in the adjacent coastal ocean, and transport of larvae on the inner continental shelf. A following segment, describes settlement of the larvae in the lower estuary and eventual transport of early juvenile stages to estuarine nursery areas. The final section provides a summary and conclusions. Points of emphasis in the review include the following: (1) the role of pheromones in courtship and mating; (2) the discovery of two distinct phases in the spawning migration; (3) the importance of chemical cues in assuring synchronized hatching of eggs; (4) the predominant effect of wind- and buoyancy-driven processes in controlling larval transport in the coastal ocean; (5) the development of mathematical models that allow critical analysis of transport processes; and (6) the combined physical and behavioral processes that facilitate transport of megalopa larvae from the estuarine mouth to nursery habitat in the lower estuary.

The blue crab Callinectes sapidus reovirus 1 (CsRV1), a double-stranded RNA virus, belongs to the Class III virus family Reoviridae and infects marine invertebrates, including the blue crab C. sapidus. Callinectes sapidus reovirus 1 levels correlate with disease progression, and high levels of infection usually result in death. To understand CsRV1 disease progression, the impact of CsRV1 infection on the translation initiation machinery in adult female C. sapidus was determined. Using transcriptome analysis of C. sapidus, sequences representing each of the three classes of metazoan eukaryotic translation initiation factor 4E (eIF4E) family members, eIF4E1, eIF4E2, and eIF4E3, as well as the eIF4E-binding protein (4E-BP), were identified as the first description of a Class III eIF4E in decapod crustaceans. Transcripts encoding the three eIF4E family members and 4E-BP are found in all tissues examined by end-point RT-PCR analysis, except for the hypodermis. In the noninfected animals, EIF4E1 transcript levels are;11.5- to 150-fold higher than those of EIF4E2, EIF4E3, or 4EBP in both hemocytes and eyestalk ganglia. In CsRV1 infected animals, transcript levels of eIF4E family members and 4EBP initially increase in hemocytes and to a much lesser extent in eyestalk ganglia. In hemocytes, EIF4E2, EIF4E3, and 4EBP transcript levels are highest at low levels of infection. By contrast, EIF4E1 transcript levels peak at moderate levels of infection. In the eyestalk ganglia, an endocrine tissue, CsRV1 infection only slightly impacts EIF4E1 and EIF4E2 levels, although more substantial increases in EIF4E3 and 4EBP are seen. These results provide the first window into how CsRV1 infection and disease progression perturb the host C. sapidus eIF4E family members and 4E-BP in different tissues, suggesting nuanced responses of the host translationalmachinery during disease progression.

Six diets with different concentrations of L-phenylalanine (10.71, 12.71, 14.71, 16.71, 18.71, and 20.71 g kg^–1 dry diet) were offered to the Pacific white shrimp Litopenaeus vannamei (Boone) reared in low-salinity water (0.50–1.20 g L^–1) to determine the phenylalanine requirement. After an 8-wk feeding trial, the results indicated that weight gain was highest in shrimps treated with 16.71 g kg^–1 dietary phenylalanine (diet P4) and that lower or higher dietary phenylanine supplementary reduced weight gain (P < 0.05). Moreover, the highest final body weight, body protein deposition (BPD), and relative muscle weight, and the lowest hemolymph urea nitrogen concentration, alanine aminotransferase, and aspartate aminotransferase activities were also found in group P4 (P < 0.05). Hemolymph metabolite profile showed that deficiencies or excess amounts of dietary phenylalanine mainly affected amino acids and energy metabolism. Polynomial regression calculated using weight gain rate, feed conversion ratio, and BPD indicated that the optimal dietary phenylalanine requirement for L. vannamei reared in low-salinity water was 15.81 g kg^–1 of dry diet, corresponding to 38.56 g kg^–1 of dietary protein.

Large-scale fishing closures are a leading tool in the spatial management of global ocean resources. This is exemplified in the U.S. Atlantic sea scallop (Placopecten magellanicus) fishery which uses a rotational scheme of temporary closed areas in both offshore and nearshore waters. The closed areas are generally hundreds to thousands square kilometers, but a group of inshore commercial scallop harvesters were interested in the effect of closing a much smaller area (3 km²), which had sustained valuable harvest before recent poor yields. To describe changes in scallop abundance and size within and around this closure, two independent surveys, a drop camera and diver transect, were conducted through industry–academic collaboration. In addition, this unusual union of a predominately offshore method, the drop camera, and inshore method, divers, was used to better interpret the results of each method. The drop camera survey results suggested that the closure significantly increased the biomass of exploitable scallops, showing that even closure orders of magnitude smaller than commonly used for scallops can be effective. Although the dive survey did not show this, understanding the uncertainties of each method helped resolve this discrepancy. Drop camera densities were calculated from a broader spatial area more representative of the entire area with increased sample size. By contrast, the dive survey provided an intensive description of scallops at each individual survey site. Combining a drop camera survey with dive stations to collect scallop measurements would provide densities from a spatial scale representative of the study area while improving shell height frequency estimation and providing biological data. In addition, this project demonstrated how stakeholder engagement supported by academic institutions and fishery managers can allow intensive monitoring of small fishery closed areas outside of government assessments.

The distribution of sessile intertidal organisms depends on many different environmental and biological variables. Of these, elevation and salinity are particularly relevant, especially for organisms that occur in salt marsh–dominated estuaries in the Southeastern United States. The ribbed mussel Geukensia demissa is a mytilid bivalve, which is an ecologically important foundation species. Despite experiencing commercial harvesting pressure in South Carolina, G. demissa currently lacks speciesspecific regulations in terms of minimum harvest size and harvest limits. Furthermore, the distribution of G. demissa within its habitat, although well described in the Northeastern United States, has not been studied in South Carolina. The goal of the present study was to develop a methodology that could be used to characterize the distribution of G. demissa using elevation and salinity data to improve the understanding of the distribution of this species at the landscape scale and to support consideration of improved management measures. Transect grid surveys for the presence or absence of G. demissa were performed at stations along a salinity gradient in the Ashley River, a tributary of the Charleston Harbor, SC, in the spring of 2017. The presence or absence of G. demissa was explained by both elevation and salinity data using a logistic regression model, and G. demissa was predicted to be most likely to occur at a high position in the intertidal zone (0.17mbelow mean high water) and at an intermediate salinity of 18. In addition, the tidal inundation period for G. demissa in this study ranged from 45 min to 6 h, and averaged 3.5 h per high tide, highlighting the physiological challenges of its typical habitat distribution.

Brown mussels Perna perna (Linnaeus, 1758) are of great economic and social importance in the aquaculture and fishing sectors in many Brazilian states. The present study aimed to compare the sizes at first sexual maturity of brown mussels (L₅₀) from natural banks exposed to different levels of anthropogenic pressure. Mussel spat were extracted along the coast of the state of Espírito Santo, Brazil, and were secured on longlines at ilha dos franceses. The human collection pressure at each location was assessed through identification of shellfish gatherers at these sites. Over a 3-mo period, 70 individual mussels from each location were removed each month for macroscopic and microscopic analysis of gonadal development. The sex ratios of the populations at Vila Velha, Anchieta and Piúma showed alternating values between the sexes. Histological analysis confirmed all of the macroscopic observations regarding sex determination and the classification of sexual stages. The average sizes at first sexual maturity of male brown mussels from different spat collection sites ranged from 22.6 to 25.2 mm. The collection pressure exerted on natural banks of Perna mussels differed significantly between the sites studied. On the natural banks where the differences in human collection pressure were recorded (at Vila Velha and Piúma), the size at first sexual maturity significantly differed for both males and females. Therefore, the results suggest that the differences in size at first maturity were due to anthropogenic pressure.

This study investigated to what extent the extrapallial fluid (EPF) of the marine bivalve Arctica islandica (Linneaus, 1767) is involved in shell formation. With in situ pH microscopy, pH gradients were identified between inner shell surface and outer mantle epithelium (OME). pH at the OMEvaried rapidly between neutral and values above 9, suggesting active H+ pumping. Microsensor measurements showed also remarkable short-term dynamics in pH and Ca²⁺ concentrations, again suggesting active ion pumping. Further focus was on pH, Ca²⁺, and dissolved inorganic carbon dynamics within the EPF to determine whether calcium carbonate precipitation is possible within the EPF. The data show that the bulk of the inner EPF rarely reaches calcium carbonate saturation and, thus, cannot be the site of shell formation. At the OME surface, however, pH levels of up to 9.5 were observed, corresponding to a 30-fold carbonate supersaturation. Thus, ion pumping by the OME can drive calcification when the OME is just a few mm distant from the inner shell surface, as it is the case in the outer EPF.

Epigenetic analyses constitute an emerging approach for better understanding of the mechanisms underlying environmental responses and their role during acclimatization and adaptation across diverse ecosystems. The expansion of environmental epigenetic studies to a broader range of ecologically and environmentally relevant organisms will enhance the capability to forecast ecological and evolutionary processes, as well as to facilitate a retrospective assessment of stress exposures in biomonitor organisms through “epigenetic footprinting” analyses. With such purpose, the present study monitored spatial and temporal variation in abiotic parameters (temperature, salinity, pH, and horizontal visibility) over a 2-y period in a mangrove ecosystem located in North Biscayne Bay (North Miami, FL). The obtained data were subsequently compared with epigenetic modifications (global genome-wide DNA methylation levels) in the flat tree oyster Isognomon alatus, used as a sentinel model organism across experimental sites. The obtained results revealed a certain level of seasonality in temporal DNA methylation patterns, which seem to be primarily associated with changes in temperature and horizontal visibility. These results constitute the first long-term study combining spatial and temporal epigenetic analyses in a marine organism in its natural environment, laying the initial groundwork to assess the biomonitoring potential of environmental epigenetic analyses.

The reproductive cycle of the tropical black-lip rock oyster Saccostrea echinata was determined at three locations in the Northern Territory, Australia. Wild oysters were collected every 4–6 wk (n = 13–23) from January 2016 until June 2017. Biometric and condition index data were collected, and tissues were histologically examined to determine gonad index (GI) and gender ratios. Seawater and air temperature were monitored by intertidally deployed data loggers, and daily rainfall data were obtained from local weather stations. A total of 527 oysters were sampled across all sites, of which 34.2% were females, 47.4% were males, 0.4% were hermaphrodites, and 18.0% were of indeterminate gender. The GI presented a clear annual cycle; values fluctuated but remained high (1.94–3.94) from October through April and were low (>1.50) from May through September, across both years. Across all sites, the GI had a strong, positive correlation with temperature (r = 0.783; df = 26; P <0.001) and a moderate, positive correlation with rainfall (r = 0.496; df = 31; P <0.05). Synchronization in spawning patterns occurred between sites, and gender ratios suggest that S. echinata is a dioecious species with low levels of functional hermaphroditism. The major finding of this study is that S. echinata spawns semicontinuously throughout the monsoon season (October–April) and has an extended resting phase throughout the dry season (May–September). The information generated in this study has a number of potential applications relating to the timing of broodstock collection and hatchery production, and it provides a broader basis for further developing S. echinata as a commercial aquaculture species.

Since 2012, aquacultured eastern oysters Crassostrea virginica have been reported by oyster farmers to display mortality approaching 30%, and in some cases 85%, in areas of the lower Chesapeake Bay, VA. Based on accounts from industry, this mortality has typically affected 1-y-old oysters between May and early July, and has tended to occur in triploid oysters, which represent the vast bulk of production in the area. During this period, samples submitted for pathology have not revealed the presence of major pathogens as a cause. In 2015, to gain deeper insight into this mortality and determine whether specific sites, ploidy condition, or genetic lines were affected, oyster seed commercially produced in early 2014 were obtained from four lines, one diploid (2N DEBY) and three triploid (3N DEBY, 3N hANA, and 3N Northern). These lines were deployed in July 2014 at aquaculture farms at five Chesapeake Bay locations: Locklies Creek and Milford Haven on the western shore, and Pungoteague Creek, Nassawadox Creek, and Cherrystone Creek on the Eastern Shore. During this study, mortality was observed to peak in June at most sites, reaching a mean mortality across all tested lines of 17.0% and a cumulative mortality for the study period of 32.0% at Nassawadox Creek, the site most severely affected by mortality that followed the expected early summer mortality pattern. Interval mortality at all sites decreased to under 5% after June, but cumulative levels for the study period reached from 8.8% to 18.6% even at the sites least affected by mortality. This represents a high level of mortality given the documented absence of material involvement by major oyster pathogens such as Hapolosporidium nelsoni and Perkinsus marinus. Infiltration of gill tissues by hemocytes, observed in up to 33% of individuals at Nassawadox Creek coincident with the increase in mortality, was the only pathology observed. Harmful algal blooms were not associated with the mortality, nor were abnormal temperatures or salinities. There was no clear relationship of mortality to oyster genetic heritage, although there was variability in susceptibility among oyster lines and interactions between lines and specific sites. At some locations and in comparison with diploids, triploid oysters appeared to be more susceptible to mortality. Mortality in triploids was coincident with the timing of peak gametogenic development in diploids. Given the lack of involvement by major pathogens and the possible association of mortality with oyster gametogenesis, future work should seek to better understand the suite of environmental stressors potentially impacting cultured oysters in these systems and their interactions with the physiology and energetics of these animals.

The filtering capacity of dense bivalve populations can exert strong controls on phytoplankton biomass, leading to increased water clarity and reduced hypoxia. Bivalves, particularly oysters, therefore are the focus of many restoration efforts and ecosystem-based management plans. The hypothesis is tested that oysters have feeding access to the classic major phytoplankton bloom of the year in winter–spring. Jamaica Bay is a highly eutrophic urban estuary where oyster restoration is being considered as a means to improve water quality. Strong winter–spring and summer phytoplankton blooms occur in Jamaica Bay, and oyster feeding rates and oxygen consumption were examined to see if oysters would be able to feed during both seasonal pulses of phytoplankton. Temperature-related feeding rates were found to vary to the degree that feeding did not occur at the cold temperatures that exist during the winter–spring blooms. Indeed, feeding rate and proportion feeding were found to be zero at 10°C, which corresponds to March–April. But feeding would be vigorous in late spring and summer. Oysters, therefore, do not have the ability to regulate a major fraction of phytoplankton during the year in Jamaica Bay and likely in the rest of the mid-Atlantic states region and New England. Feeding rates are much higher during the time of the summer blooms, and oysters in shallow well-mixed waters would, therefore, have access to feeding and possibly control of phytoplankton biomass at this time.

The leading cause of seafood-borne illness in the United States is Vibrio parahaemolyticus, whereas Vibrio vulnificus has the highest case fatality rate from wound infections of any foodborne pathogen. The Food and Drug Administration (FDA) uses a method of bacterial determination in oyster tissues termed “most probable number” (MPN) to enumerate Vibrio spp. abundance. This study used the development of two multiplex qPCR methods for the enumeration of total and pathogenic V. parahaemolyticus and V. vulnificus in oyster tissue using plasmid controls. Oysters, Crassostrea virginica, were collected from aquaculture farms in Wareham, MA, and Portsmouth, RI, from May to October 2014. Food and Drug AdministrationMPNand MPN-qPCR methods were compared and showed that FDA methods had higher values for both locations than MPN-qPCR methods. Throughout the summer at both locations, V. parahaemolyticus was most abundant with a majority being trh⁺ strains. Although serotypes were not directly tested for, tdh⁺ and trh⁺ strains were identified, suggesting a low possible occurrence of O4: K12 and no possible occurrence of O3:K6. In some samples, Vibrio alginolyticus was detected, indicating that trh⁺ percentages may be attributed to either V. parahaemolyticus or V. alginolyticus because of the similarity of the trh gene. The results from this study indicate the poor specificity and quantifiability of the FDA MPN method. This work also demonstrated that the use of plasmid controls for routine molecular methods to be used in a laboratory provided a reliable and consistent source of positive controls to compare against unknown samples for the abundance of V. parahaemolyticus and V. vulnificus.

The queen conch Lobatus gigas is the second largest commercial fishery in the Caribbean, and overharvesting has resulted in significant population declines. Depleted populations are at greater risk of stochastic events, including disease epidemics; however, disease diagnosis in L. gigas has been limited by the lack of standard procedure and histological reference material. This manual outlines a systematic technique for postmortemexamination and compiles a comprehensive histology atlas to facilitate research regarding the pathology of L. gigas. Methods for euthanasia, dissection, sampling, and fixation are described, which produced optimal presentation and preservation of tissues. The recommended approach includes anesthesia with magnesium sulphate, extraction from shell, and euthanasia by incision through ganglia posterior to the buccal mass, followed by exposure of all tissues using four incisions. Anatomy is described for both sexes and standard sample locations are established. Tissue fixation is optimal using Davidson's formula. A histological reference for 16 tissues, nine of which were described for the first time in this species, is presented, including the anus, columellar muscle, digestive gland, esophagus, foot, ganglia and nerves, gill, gonad, heart, hypobranchial gland, kidney, mantle, nephridial gland, osphradium, small intestine and rectum. This manual is the first necropsy guide and histology atlas for L. gigas, a baseline resource for researchers monitoring health and disease in the species.

The jumbo squid (Dosidicus gigas) has been considered a species with a semelparous life history, and this assumption has been erroneously adopted without histological evidence. Recent studies suggest that this species can spawn more than once during its life span. To identify the reproductive strategy of jumbo squid, qualitative and quantitative analyses were used in this study. Biological data were collected fortnightly from March 2008 to November 2009 off the coast of Santa Rosalía, Baja California Sur, Mexico. The histological analyses showed five stages of development: previtellogenesis, vitellogenesis, postvitellogenesis, spawning, and postspawning, with the simultaneous presence of oocytes at different substages. These results were confirmed by the presence of multiple cohorts of oocytes at each ovarian stage. Analysis applied to resting females of D. gigas confirmed that the postovulatory follicles were simultaneously found with previtellogenic oocytes denoting the ovarian recovery. The presence of postovulatory follicles at all ovarian stages and in individuals throughout the mantle length (ML) structure (from 32 to 82 cm) was an indicator of multiple spawning events. During 2008 and 2009, four ML groups (41.2, 48.5, 55.2, and 68.5 cm) and threeMLgroups (39.9, 47.8, and 53.9 cm) were observed, respectively. In conclusion, the evidence of postovulatory follicles in resting females of D. gigas indicates that the reproductive strategy of jumbo squid is iteroparity.

Population genetics is a valuable tool in understanding various aspects of biological invasions, such as pathways of invasions, predicting invasion success, and determining dispersal capabilities. The island apple snail (Pomacea maculata), which is native to South America, is an invasive gastropod currently established in several southeastern states in the United States, including South Carolina and Georgia. Despite its known negative impacts in invaded regions, knowledge of P. maculata specific to South Carolina is limited, and an in-depth analysis of the population genetic structure of P. maculata in South Carolina and Georgia has not been conducted. The present study aimed to genetically characterize P. maculata individuals from three locations in South Carolina and five locations in Georgia using a suite of 14 microsatellite markers. Population genetic structure was determined using pairwise FST comparisons, isolation by distance analysis, and a likelihood-based approach. Genetic diversity indices, effective population size, inbreeding coefficients, and Garza–Williamson indices, which is the mean ratio of number of alleles to the range in allele size in a population and can be used to detect recent reductions in population size, were all calculated. Significant genetic structure was observed in all sampling locations, apart from the two sites in Kingsland, GA; a weak correlation was found between genetic distance and geographic distance across all the sites; and genetic diversity was low across all loci at the eight sites. Garza–Williamson indices all showed likely recent reductions in population size. These results indicate that the populations in South Carolina and Georgia were probably the result of separate introduction events and that these populations are genetically isolated. The low genetic diversity observed could indicate that these populations are susceptible to eradication efforts and/or stochastic environmental changes.

The physiological tolerances of invasive species can be important predictors of geographic range expansion. Further, determining salinity tolerances can inform natural resource managers as to the ability of a freshwater species to invade estuarine habitats. Native to South America, the island apple snail Pomacea maculata (family Ampullariidae) is an invasive freshwater gastropod that is currently established across much of the southeastern United States, including South Carolina. The island apple snail is considered an invasive species because of the negative impacts of its intense grazing, high fecundity, and ability to out-compete native species. Further, the island apple snail can also serve as a potential to host the rat lungworm nematode parasite (Angiostrongylus cantonensis), which can cause eosinophilic meningitis in humans. Despite these known potential impacts, knowledge of biology of P. maculata in South Carolina is limited. The objective of this study was to determine the salinity tolerance of P. maculata hatchlings. Although previous studies on the salinity tolerance of P. maculata have been conducted, physiological tolerances can often vary regionally. Because of this potential for regional differences in salinity tolerance, determining the salinity tolerance of P. maculata specific to South Carolina is important in improving the understanding of its invasion/dispersion potential among brackish habitats in South Carolina. This knowledge will help resource managers to develop more effective control and/or eradication strategies. Newly hatched P. maculata obtained from egg clutches deposited by adult snails in a biosecure laboratory were placed in each of five salinity treatments (0, 4, 8, 12, and 16), and mortality was assessed daily for 14 days. Intraspecific variation at the regional scale in salinity tolerance has been documented in other species; thus, the survival of hatchlings from four separate mating pairs was assessed. Kaplan–Meier survival analysis was conducted to determine median survival probabilities, and differences in mean survival were determined using Kruskal–Wallis tests with post hoc Dunn's tests. An LD₅₀ value was determined by conducting a logistic regression analysis. A survival of 100% was observed at 0 salinity and 0% survival was observed at salinities of both 12 and 16. Survival probabilities at salinities of 4 and 8 were 0.925 and 0.156, respectively. There were no differences in survival among hatchlings from the different mating pairs. In relation to salinity, an LD₅₀ value of 6.39 was calculated. These results demonstrate the ability of P. maculata to survive salinities as high as 8, suggesting that this species could be capable of becoming established in upstream estuarine habitats in coastal South Carolina.

The New River Basin (NRB) of Tennessee has many rare endemic aquatic communities. One such community is that of freshwater mussels, which are experiencing a precipitous population decline due to the fouling and pollution of their freshwater systems. Silos containing live individuals of the nonnative Asian clams (Corbicula fluminea) were placed in several localities in streams of the NRB that receive mine drainage. This drainage is commonly associated with elevated conductivity typical of pollution that may impair native mussel health. This study of five impacted streams within the NRB, and a control stream of similar ecology, uses a stepwise multiple regression analysis to test this association. After accounting for factors such as temperature, results confirm that growth rates of these sentinel clams are significantly related to conductivity, and that these clams may be useful bioindicators of stream habitat quality for native mussels.

Accurate estimates of fecundity and spawn timing are essential to fisheries management but can be difficult to obtain in nonaggregating broadcast-spawning species such as the commercially harvested sea cucumber Parastichopus californicus. Individuals of P. californicus collected from Southeast Alaska (SEAK) over 3 y were examined to determine the timing of spawning based on seasonal variations in gonad indices (GI). Gonad indices measured at different time points in the annual reproductive cycle were compared with gonad lipid content and egg development to validate GI as an indicator of gonad maturation. Fecundity was estimated as the total number of eggs and as the number of viable eggs produced in both live-spawned and strip-spawned animals. Results suggest spawning may occur slightly earlier than previously reported in British Columbia, Canada, where fecundity was about two times higher than in SEAK. Seasonal changes in gonad total lipid and maturation stage were recorded. Gonad index was moderately correlated with both gonad lipid content and maturation stage. Estimates of total fecundity and viable eggs based on live spawning did not significantly differ among the 3 y sampled. Live spawning yielded comparable estimates of total fecundity and viable eggs per gram female wet weight compared with strip spawning. These findings inform aquaculture efforts and management of the commercially harvested SEAK population of P. californicus.

This study investigated the variability of molluscan assemblages of rock pools according to location and pool size. The study was carried out in three sandstone reefs on the west coast of Ceará in northeast Brazil. The size parameters evaluated were surface area, depth, and volume of pools and pool-ocean distance. The molluscan assemblages were characterized by ecological diversity descriptors (abundance, species richness, diversity, and evenness). A total of 43 species of molluscs belonging to the classes Bivalvia, Gastropoda, and Polyplacophora were identified. The most relevant species for discriminating among the assemblies were Eulithidium affine, Cerithium atratum, Tegula viridula, and Ischnochiton striolatus. Results indicated a clear local difference in the structures of the assemblages; however, they did not differ according to the size of the pools. This indicates that sites may play a more important role in the structure of molluscan assemblages in rock pools than the association with pools.