Evaluating the spatial scale of biological variation in marine species aids understanding of the ways in which environmental selection pressures can shape life histories, population demography, and morphological traits. The Pacific geoduck Panopea generosa is an ideal candidate to investigate patterns of life history variation and morphological plasticity, as the species occurs over a large geographic range, inhabits different marine environments, and experiences intense fishing pressure in some locations. Six populations were sampled from Washington to Baja California (Mexico), from a mix of subtidal and intertidal habitats, to evaluate evidence for geographic variation in demography, life history, and shell morphology. Results provided evidence for a latitudinal cline with larger clams occurring in locations characterized by colder water temperature. Von Bertalanffy growth model analyses revealed significant spatial variation in asymptotic lengths across sampling locations. Correlations between environmental variables (sea surface temperatures and chlorophyll a) and growth parameters indicated that clams reached larger sizes at locations that were cooler and had higher primary productivity. Age structure and longevity analyses demonstrated that life expectancy was significantly lower at intertidal sites than at subtidal sites, potentially in response to increased fishing pressure at sites more easily accessed by humans at low tide. Morphological analyses (i.e., geometric morphometrics) revealed significant spatial differences in shell shape that did not follow a latitudinal pattern, but may be better explained by site-specific differences in sediment characteristics or other selective pressures in the environment. In a management context, these results may inform efforts to develop spatially explicit regulations for the Pacific geoduck fishery. Finally, this study provides a general framework for evaluating demographic variability in shellfish populations across large spatial scales.

The embryonic and larval developmental stages of the geoduck clam Panopea globosa were described, and the size at different ages post-fertilization were evaluated using both shell length (SL) and shell height (SH). Gametes were obtained from wild ripe broodstock and fertilized under controlled conditions (22.15°C, 35‰, pH8.4). Fertilization and meiosis were confirmed by single membrane formation (after ∼5–10 min) and extrusion of the first polar body (after ∼15–20 min), respectively. Trochophore larvae (94.80 ± 0.74 µm SL and 82.92 ± 4.69 µm SH) were observed 17.5 h after fertilization. Veliger larvae (146.36 ± 17.54 µm SL and 121.78 ± 15.96 µm SH) were observed 43 h after fertilization. Umbo growth was apparent 7 days after fertilization, and pediveliger larvae (355.36 ± 20.99 µm SL and 313.64 ± 21.24 µm SH) developed 21 days after fertilization. The growth of SH and SL were best described by a linear function of time (T = days) from fertilization to the pediveliger stage (SL = 12.04 T + 81.40 and SH = 10.69 T + 67.33). The linear relationship between SL and SH indicates that the rate of SH growth during larval development of P. globosa is smaller than that of SL (SH = 0.875, SL = -2.20). The results demonstrate that highly uniform larvae sizes can be obtained from spawning runs in controlled environmental conditions. This is the first description of the development of P. globosa from the embryonic stage to early juvenile stages.

The identification of the sex and sexual maturity of geoducks (Panopea japonica) is difficult because the outer shape of the males and females is indistinguishable. Moreover, depending on their size or age, the annual maturation cycle can vary. Vitellogenin (VTG) is a precursor protein of egg yolk. It has been studied as a biomarker for sex identification in geoducks. This article reports on the cDNA cloning of the P. japonica VTG gene for the VTG fragment. It was found to exhibit homology to known VTGs isolated from other marine molluscs, with more than 50% homology with oyster VTG. An enzyme-linked immunosorbent assay was developed to quantitatively detect the VTG level in geoducks. The VTG polyclonal antibody could recognize the extracted VTG in females, but the level of VTG in males was undetectable, providing a basis for an immunological assay for the identification of the sex and female maturational status of geoducks. Thus, this study established a simple and quantitative technique for the rapid identification of sex and/or maturation of females by using VTG in the hemolymph as a biomarker for the sampled geoducks without dissection or seriously injuring them.

This study was performed to obtain information on the sex ratio, size at sexual maturity, and main spawning period of the butter clam Saxidomus purpuratus in Korea to contribute to the management of fisheries resources of this species. The age-specific sex ratios (female:male) of S. purpuratus were 1:2.20 (31.3% female) and 1:1.03 (49.2% female) in the 0+ and 1+ y classes, respectively, illustrating the initially higher percentage of males in the butter clam population. From the 2+ y class onward, however, the percentage of females in the population tended to increase with age. The shell length at sexual maturity was analyzed using a logistic regression model, and was determined to be 54.5 and 45.5mmfor females and males, respectively. The gonad index displayed a definitive pattern of seasonal changes, with high values in the spring and fall and low values in the summer and winter for both males and females. The butter clam S. purpuratus was found to have two spawning seasons per year, with the main spawning period being in May–June.

The clam Meretrix petechialis is a commercially important marine bivalve mollusc, but its population has been greatly reduced because of overexploitation and habitat destruction. In this study, a set of novel expressed sequence tag–derived microsatellite makers were developed and characterized in the clam M. petechialis. The number of alleles at each locus ranged from 4 to 30, with an average of 10.9 alleles per locus. The observed and expected heterozygosities varied from 0.100 to 1.000 and from 0.538 to 0.973, with an average of 0.713 and 0.750, respectively. The polymorphic information content value ranged from 0.423 (Mmt09) to 0.956 (Mmt47), with an average of 0.695. The cross-species amplification transferability of nine microsatellite loci to three closely related species ranged from 29.17% to 100%. These microsatellite loci will be useful for further investigation of the population structure and conversation genetics of this species.

Atlantic surfclams support a major commercial fishery in the western North Atlantic Ocean with landings consistently between 15,000 and 25,000 metric tons since 1982. The stock is not and historically has not been overfished nor has overfishing occurred; however, in recent years landings per unit effort have declined. Surfclams are a biomass dominant on the continental shelf and a bellwether of climate change in the northwestern Atlantic. This study investigated the relationship of broodstock and recruitment during a period when Mid-Atlantic warming initiated a shelf-wide shift in the surfclams range. A species distribution function model was used to assess the effective area occupied by surfclams for five study regions (Delmarva, New Jersey, Long Island, Southern New England, and Georges Bank). The effective area occupied by small surfclams was consistently much greater than that for large (≥120 mm) surfclams. Three independent statistical analyses of the stock-recruitment relationship found little evidence of a significant association in any of the five regions, suggesting that factors besides spawning stock biomass (SSB) are primary determinants of recruitment success. Interannual variability in recruitment, in part associated with variations in larval transport and in part associated with spatially different rates of mortality post-settlement, is an important source of uncertainty and warming bottom waters driving surfclams into new habitat may decouple any inherent interaction between recruits and SSB. A recruitment index obtained from a fishery-independent survey across the range of the stock, as a consequence, is unlikely to usefully presage changes in abundance of the fishable stock. The wider distribution of settlers relative to the fishable stock, however, positions the species well to respond to changing bottom water temperatures as Mid-Atlantic warming continues.

The tropical clam Anomalocardia brasiliana is a commercially important bivalve living along the south Atlantic coast of Latin America. Harvest of natural stocks is the principal method for supplying market demand—the market average price ranging from 5 to 10 US$ per kilogram of meat. As a first step in the development of hatchery techniques for A. brasiliana seed production, this study examined the effects of temperature and salinity on conditioning broodstock for spawning. Two treatments tested conditioning at 25°C at salinities of either 30 or 35. A third treatment examined the effects of an initial 10-day conditioning at 16°C followed by a gradual temperature increase to 25°C at a salinity of 35. As a control, clams were sampled from the wild over the same experimental period. Tissue samples were taken at the initiation of the experiment and at 15, 30, 45, and 55 days of conditioning and examined histologically to determine changes in the sexual development of the clams. Four reproductive stages were identified during the experimental period: gametogenesis, mature, spawned, and absorption. The treatment with the initial 10-day conditioning period at 16°C demonstrated that it is possible to synchronize gamete development in both males and females to result in the maximum proportion of mature broodstock at 55 days of conditioning.

Wild clams of Meretrix meretrix and Cyclina sinensis were collected from intertidal flats of Shuangtaizi estuary during low tide in 2016. Morphometric traits including shell length (SL), shell height (SH), shell width (SW), and total body weight (TW) of the clams were measured. Correlation, path, and regression analyses were conducted to evaluate the relationship between morphometric traits and total body weight and determine the optimal indices for artificial breeding of M. meretrix and C. sinensis. Significant differences in correlation coefficient among various characteristics were found. Shell height and SW showed the strongest influence on total body weight. The optimal regression equation of the measured traits was established in both clams by using a stepwise regression method: TW = –27.404 + 0.948 SW + 0.422 SH + 0.291 SL for M. meretrix and TW = –36.965 + 1.107SH + 0.564SW for C. sinensis. These results provide baseline information for selective breeding and conservation management of the two commercially important clam species in Shuangtaizi estuary.

Fluid and its associated mucus from the pallial (mantle) cavity of the ribbed mussel Geukensia demissa (Dwillyn) from Black Rock Harbor, Bridgeport, CT, inhibited the growth of both Gram-positive (Staphylococcus aureus) and Gramnegative (Escherichia coli) bacteria in antimicrobial assays. A significant reduction in size after 24 h was noted in E. coli grown in the presence of ribbed mussel fluid. Mussel-soluble lysozyme levels in the pallial cavity fluid averaged 0.019 + 0.018 relative fluorescence units/mg protein, and no seasonal pattern of lysozyme activity was found (P = 0.522). During the course of the study, copper concentrations ranged from 0.09 to 0.37 ppm and zinc concentrations from 0.17 to 0.66 ppm in the pallial cavity fluid. These values were only slightly higher than the concentrations of these metals found in seawater samples taken at the site, indicating only very low levels of sequestration of heavy metals by G. demissa in the pallial fluid cavity. A comparable study of oysters (Crassostrea virginica) from the same site found lysozyme levels 10 times higher and zinc concentrations two orders of magnitude greater than in that in mussels reported here (Brousseau et al. 2014). These results suggest substantial interspecies variation in profiles of defensive agents involved in antimicrobial activities of marine bivalves and highlight the need for additional studies to characterize these differences.

Reproductive condition of Pecten sulcicostatus from False Bay, South Africa, was assessed monthly from August 2010 to November 2011 by determining the gonadosomatic index (GSI) and by monitoring associated histological changes within the gonads. Simultaneous measurement of temperature and chlorophyll a concentrations at the site of scallop collection provided insight into the conditions controlling the reproductive cycle. Direct spawning induction was also attempted monthly, using four spawning techniques: desiccation, food deprivation, thermal shock, and intragonadal injection of the hormone serotonin. The reproductive cycle of P. sulcicostatus demonstrated seasonality in that the GSI was highest from June to September. An increase in bottom temperatures through winter and spring is a likely factor inducing spawning. The highest phytoplankton biomass in summer and autumn is likely to contribute to the winter buildup of gonads. Injection of serotonin was the only method that successfully induced spawning. Gametogenesis occurred in all months, except that oocytes were not released in November and December.

The effect of two temperatures (14°C and 18°C) and incubation systems (artificial versus female care) on the embryonic development of Octopus vulgaris was studied. Octopuses (six females and two males) were captured in the Ria of Vigo (Northwest Spain). Egg batches were divided into two groups: one left with female care, and others were incubated with artificial aeration. The results indicate that the type of incubation did not affect the embryonic development, whereas temperature had a marked effect on it. The duration of embryonic development was 40 days at 18°C and 67 days at 14°C. Results suggest that a reduction of around 24 days °C^–1 can be obtained when O. vulgaris embryos are incubated into the temperature tolerance range of this species. Results showed that temperature modulated in a different form the embryonic development, at least until stage XIII, where embryos at 18°C showed lower values of eggs and embryo length than embryos at 14°C. The proportion of arm/total length was 21% higher in embryos at 14°C compared with 18°C, suggesting that in the first phases of embryo development, muscle development is favored at low temperature. Results showed that embryos at 14°C and 18°C had no differences in two critical processes, that is, nervous system synthesis (measured through eye synthesis) and organogenesis (measured through mantle length). The fact that there were no differences between hatchlings developing from embryos at both experimental temperatures demonstrates that O. vulgaris embryos can be favored if spawn occurs at relatively low temperatures.

The head withdrawal reflex is a behavior that has been reported in young pelagic squids (paralarvae) and involves retraction of the head, arms, and proboscis (fused feeding tentacles) into the mantle cavity when the animals are disturbed. The present study investigated which artificial stimuli (mechanical, chemical, or light) trigger this behavior in three oceanic ommastrephid squid species: Sthenoteuthis oualaniensis, Eucleoteuthis luminosa, and Todarodes pacificus. All stimuli triggered ball formation and chromatophore expansion. During the early paralarval stage, the head was completely withdrawn into the mantle cavity, and the squid formed a ball posture with expanded orange chromatophores. This response might make it difficult for predators to recognize and consume the squid or it might facilitate feeding.

The Eastern Oyster Crassostrea virginica is an important component of the ecology of Apalachicola Bay, Florida, and the economy of the region. Although oyster reefs in the Bay occur in both tidal zones, subtidal reefs have received the most attention because they support most of the oyster fishery. The present study provides new information on the distribution, condition, and ecology of the intertidal reefs, and assessed the general utility of high-resolution satellite imagery for routine monitoring of the extent and condition of intertidal oysters. Using online, freely available color imagery and manual interpretation, a total of 782 individual reefs ranging in size from ∼3 m² to 3.9 ha (= 9.7 acres) and covering a total of 94 ha (233 ac) of bottom area were mapped. Field inspection and sampling of 100 individual intertidal reefs on November 12–16, 2016, confirmed wide differences in the number and areal coverage of reefs in the three major geographic regions in the Bay: 433 reefs covering a total of 56 ha (139 acres) in the western area (St. Vincent Sound); 113 reefs covering 8 ha (19 acres) in the central area; and 236 reefs covering 30 ha (75 acres) in the eastern area (St. George Sound). Most reefs in the western portion of the bay consisted of recently dead (“box”) oysters in all size classes, suggesting a recent massive mortality event. Mean densities (all size classes combined) of live oysters in the central and eastern areas were 42.9/m² (±7.39; 1 SE) and 99.3/m² (±13.22; 1 SE), respectively, with an overall mean shell height of 23.6 mm. Size-frequency histograms indicated only two year classes of live oysters, and the largest oyster collected was 84 mm. Although detailed quantitative comparisons with subtidal reefs were not possible, data from the present study suggest that intertidal reefs cover much less bottom area of the bay, but may contain much higher live oyster densities. The present study also demonstrated the use of high-resolution satellite imagery for mapping reefs as small as a few square meters in surface area, and the potential for estimating relative reef condition measured by live oyster density.

Complete mitochondrial genomes of Pinctada fucata martensii and Pteria penguin were sequenced. The P. fucata martensii mitogenome was 31,435 bp long, which made it the longest genome so far published in the Pinctada and Pteria. The mitochondrial genome of P. penguin lacked three transfer RNA (tRNA) genes and had one duplicated tRNA gene; this mitogenome has the fewest tRNA of any mitogenome so far available in the Pinctada and Pteria. Both mitogenomes were strongly skewed away from C in favor of G and away from A in favor of T. The mitogenomic gene order in these two species was incongruent with mitogenomic gene orders for other species of Pteriomorphia, and Pteria penguin was placed as sister to all other Pinctada species. This study provided insights into the evolutionary relationships among Pteriidae species.

Preoperative treatments, such as starvation, lead to an improvement in receptiveness of nucleus insertion and reduction in the postoperative stress responses of oysters. And the nacre-secreting mantle graft (saibo) solution can maintain the balance of osmotic pressure inside and outside cells and ensures normal cellular activities after operation, which is also a key aspect of pearl culture. In this study, the combined effects of gonadal elimination (caused of starvation) and saibo preservative solution on the physiological responses and energy budget of the pearl oyster Pinctada martensii were investigated. The results showed that the absorption efficiency, clearance rate, respiration rate, oxygen-to-nitrogen ratio, and scope for growth, except excretion rate, were significantly decreased under complete gonad elimination treatment. No significant effects under saibo preservative solution and between the two stressors were observed for physiological indices. Moreover, the subsequent pearl production results showed that complete gonadal elimination negatively influenced pearl performance. The present study demonstrated that partial gonadal elimination treatment was more beneficial to pearl production than complete gonadal elimination.

The present study describes the effects of various wavelengths of light on locomotion and byssal reattachment activities in the pearl oyster Pteria penguin, the most widespread cultured winged oyster for the production of valuable mabé pearls. Responses of pearl oysters to light have not yet been carefully observed and documented, despite the fact that light is known to influence the positioning of animals within the water column subject to local environmental conditions. To appropriately assess oyster movements and subsequent byssal reattachment, juveniles were filmed during unnatural light–dark cycles, alternating light and darkness every 6 h. Another experiment, to observe reactions to different light colors, was carried out by subjecting juveniles to either red or blue light during a continuous observation period of 24 h. Byssal reattachment for each juvenile was recorded at the end of each observation period. Light, independent of its color, strongly inhibited both locomotion and byssal reattachment activities in juveniles. Moreover, locomotion was observed to be unrelated to the shell size, but it is suggested that a large byssus may be responsible for inhibiting movement by preventing complete extension of the foot. High byssal reattachment rates to substrata under darkness in oyster juveniles is an important factor to take in consideration after detachment events during cleaning or when transplanting seeds to farm grounds.

Genome size (C-value) and the percentage of adenine and thymine nucleotides in the genome (AT content) are fundamental characteristics of every species, and very important parameters in molecular cytogenetic and phylogenic studies, and for the progress of whole-genome sequencing. In this study, the C-value and AT content of nine abalone species inhabiting the Northwest Pacific (around Japan), Southeast Asia, South Africa, and Oceania were determined using flow cytometry. C-value ranged from 1.32 pg for Haliotis varia (Southeast Asia) to 2.01 pg for Haliotis laevigata (Oceania), and AT content ranged from 58.0% for Haliotis planata (Southeast Asia) to 66.3% for Haliotis diversicolor aquatilis (Southeast Asia). Reported chromosome numbers ranged from 2n = 32 to 36, and were higher in Oceanian, South African, and Northwest Pacific species (2n = 36) compared with the Southeast Asian group (2n = 32). This increase of chromosome number in the Oceanian species seems to be related to an increase in the DNA amount, unlike that of Haliotis midae (South African species). An increase of the C-value associated with an increase in DNA amount was also shown in the North Pacific group. These results suggest that increases in the DNA amount occurred independently in the ancestor of each of the different lineages.

The mating behavior of Echinolittorina lineolata (d'Orbigny, 1840) as well as spawning and larval development was observed in the laboratory. The egg capsules, when deposited, are translucent with a peripheral base and a dome-shaped top with four concentric rings and contain a single white egg. The embryos develop inside the capsules immersed in a gelatinous liquid (albumin). Veliger larvae hatched 96 h after capsule laying and survived free for up to 3 days in the aquarium but did not undergo metamorphosis. Echinolittorina lineolata can be considered to have a “mixed” development.

The carnivorous keystone muricid species Concholepas concholepas (Bruguière, 1789) is known in Chile as “loco,” in Perú as “pata de burro, tolina, or chanque,” and in internationalmarkets as “false abalone.” The loco is present along the coast of Chile, in theArchipelago of Juan Fernández and in southern and central Perú, and its range of distribution spans over 5,000 km of intertidal and shallow subtidal reefs. In Chile, the loco is a traditional food resource and has been heavily exploited since the early Holocene by intertidal food-gathers and free divers, and since the 1950s/60s by a small-scale artisan fleet of hookah-divers. In Chile, since the mid-1970s, the species has been mainly exported (foot-meat) to Asian markets, and between 1976 and 1980 market demands acted as a major driving force behind overexploitation of the loco. Since the 1990s, its fishery moved from an open access regime to a comanagement regulated policy based on territorial user rights for fisheries (TURF) and reproductive fishery bans. The loco, as an iconic species, played a key role in the implementation of TURF. In Perú, the loco fishery operates under a reproductive ban fishery regime and its export started in the late 1990s. In Chile, the loco is by far the most intensely studied of all exploited shellfishes in terms of evolution, paleobiogeography, biogeography, life history, behavior, physiology, ecology, genetics, and fishery. Moreover, the loco has been used as a biological model to study responses to global stressors such as ocean warming and acidification. During the past 20 y, several laboratory experimental attempts have been made to advance experimental, pilot, and commercial aquaculture of the loco. Nevertheless, the available information shows that no reliable and repeatable pilot or massive aquaculture protocols have yet succeeded. In this study, the extensive field and laboratory information for the most relevant life history phases of the loco, such as reproduction, mating, brood-stock holding, egg capsule deposition, larval posthatching, growing to competence, larval feeding, settlement and metamorphosis to juvenile stages, and pilot growing experiences to adult sizes are reviewed. In light of the available information, the most critical aquaculture bottlenecks are identified. Among them, the existence, from hatching to competence, of a long larval planktonic phase of about 3–4 mo, and the existence of cannibalism during postsettlement confined laboratory conditions are highlighted. Moreover, key aspects of the larval rearing of the loco, such as densities, field and laboratory food items, and temperatures are reported. The field collection of (1) competent larvae of locos in inshore coastal plankton; (2) new settlers from rocky shores; and (3) new settlers from fishery-discarded conspecific shells are also discussed. The collection of competent larvae was followed by laboratory induction to settlement and by two consecutive postsettlement rearing/growing phases (laboratory and field conditions) to overcome difficulties associated with the long larval phase and to speed up the time required to reach trading sizes. Furthermore, collection of new settlers was followed by rearing experiments under both laboratory and field conditions. The need of high demands of live prey (mainly mussels) during the laboratory rearing of the early benthic stages of loco is discussed, emphasizing that to implement ecologically sustainable aquaculture practices, parallel aquaculture of the appropriated prey is needed. A review of what is already known regarding the biology of C. concholepas is provided along with progress and pit-falls for the aquaculture of this species. The practicality for its aquaculture and the main challenges ahead are also discussed.

The reproductive biology of the red crab Pleuroncodes planipes, an abundant but unfished galatheid species, was studied using specimens collected from the west coast of Baja California, Mexico, in November 2006 and March 2007. Crabs were caught with a bottom trawl at predefined stations. Sex ratios were not significantly different from 1:1 (P > 0.05). The six stages of oogenesis and 10 oocyte substages in P. planipes are described. Results suggest a synchronous maturation pattern with multiple spawnings during the breeding season. In males, spermatogenesis occurs as a continuous process. The estimated cephalothorax length (CL) at 50% sexual maturity for females was 23.6 mm and 22.3 mm for the November 2006 and March 2007 cruises, respectively; for males, it was 26.8 mm and 25.3 mm. Batch fecundity of females ranged from 267 to 25,674 eggs for red crabs 9.5–33.87 mm CL. Batch fecundity was positively correlated with CL (P < 0.05; r² = 0.84 and 0.93).

This study analyzed the interannual changes in the fraction of female brown shrimp Farfantepenaeus californiensis that were mature by assessing the performance of a 3-parameter versus a 2-parameter logistic model of maturity at length and the effect on the magnitude of length at first maturity (L50). Shrimp biological data were registered monthly from 1995 through 2015, off the southwestern coast of the Baja California Peninsula, Mexico. The model was fitted to the data by assuming two conditions for the asymptote, which represents the proportion of mature females: (1) asymptote equal to 1 (2-parameter), and (2) asymptote less than 1 (3-parameter). On the basis of Akaike's information criterion, the logistic model with asymptote less than 1 was selected as the best model. Therefore, the asymptote varied from 0.34 to 0.92, and the L₅₀ ranged between 138 and 172 mm in total length. The estimates of the L₅₀ for the 3-parameter model were lower than those for the 2-parameter model, avoiding misinterpretation of this quantity used in management. The results show a decline in the proportion of mature females, indicating that not all the female shrimp in the population spawn every year. The use of the 3-parameter model provided a better representation of the observed data and reliable parameter estimation.

Eyestalk ablation is a common technique to induce spawning in marine shrimps. Currently, little is known about how this technique affects nutritional preferences (energy sources) in response to stress induced by eyestalk ablation during reproduction and growth. Thus, this study investigated the physiological effects of eyestalk ablation on hemolymph nutrient (glucose and protein) utilization and plasma protein expression of the female giant freshwater prawn (Macrobrachium rosenbergii). Sixty female M. rosenbergii prawns weighing 15.6 ± 0.3 g were divided into unablated (no eyestalk ablation, n = 30) and ablated (unilateral eyestalk ablation, n = 30) groups. The groups were then allowed to undergo reproductive and nonreproductive molting cycles. During normal molting, hemolymph protein (1,339.90 ± 95.08 mg/mL) concentrations decreased in the postmolt stage during the reproductive cycle, indicating that protein was used to attain full ovarian maturation, as evidenced by a large rise in the Gonadosomatic index value (8.47% ± 0.52%). The ablated group was vulnerable to stress, especially during the premolt (reproductive) stage, as indicated by a significant (P < 0.05) reduction in hemolymph protein concentrations, whereas no such stress-related effect was observed during the premolt (nonreproductive) stage. Interestingly, protein profiles were unaffected by eyestalk ablation, as shown by the similarity in profiles in both the unablated and ablated groups. Using a proteomic approach, fragment hemocyanin subunit 2, an immune-related protein, was identified in the ablated group. Overall, the results suggested that protein appeared to be the main nutritional source for reproduction and growth during short-term stress associated with eyestalk ablation, which led to stimulation of hemocyanin subunit 2.

Bivalve molluscs provide water quality benefits throughout mid-Atlantic watersheds, such as Chesapeake Bay and the Delaware River basins. Whereas most of the attention has focused on the role of the eastern oyster Crassostrea virginica, there are many other bivalve species, in both salt and fresh waters, that provide similar benefits. This review summarizes current knowledge regarding the capacity of diverse mid-Atlantic bivalves to filter particles and potentially enhance water clarity and quality. Species with the greatest clearance rates and population carrying capacity were also considered for their restoration and enhancement potential. Compared with eastern oysters, several additional species of saltwater bivalves and freshwater mussels are reported to filter water at rates that merit restoration attention and have been shown to attain significant population sizes. More work is needed to estimate system-carrying capacity and to eliminate restoration bottlenecks for some species—all bivalve species have constraints on their distribution and abundance. Nevertheless, a diversified, watershed-wide bivalve restoration strategy is likely to be more successful than a monospecific focus because it would address pollutant issues in more diverse places and multiple habitats along the river to estuary continuum.

Aconsequence of land-use change and increasing human population in the United States and Central America has been an increase in nitrogen availability to coastal systems. Whereas many studies evaluate the influence of anthropogenically derived nutrients in modern oceans, fewer studies evaluate nutrient sources in coastal environments before the 1960s. This study used stable C and N isotope values of 35 big-claw snapping shrimps (Alpheus heterochaelis) and 48 ivory barnacles (Balanus eburneus) across the Gulf of Mexico, southeast coast of the United States, and the Caribbean over 121 y to examine whether human-derived nitrogen was used by coastal invertebrates. Gulf of Mexico and southeast U.S. collections were divided into preand post-1960 groups for analysis, roughly coinciding with the increase in fertilizer use associated with the “Green Revolution” and large coastal population increases. For B. eburneus, δ¹⁵N decreased in the coastal United States after 1960, but that was not the case for A. heterochaelis. ¹⁵N-depleted fertilizer would be quickly incorporated by filter-feeding B. eburneus (via plankton). By contrast, the scavenging, omnivorous, A. heterochaelis would obtain more N from heterotrophic organic matter more isolated from the ¹⁵N-depleted fertilizer signal. The Caribbean A. heterochaelis incorporated seagrass C and N. Local variation in N sources from the different collection areas was clearly observed. Although anthropogenic N has been making its way into the filter-feeding barnacles, it is not as apparent in the scavengers.