Atlantic Surfclam Spisula Solidissima Research Articles

Structural and dynamic characterization of the hexa-coordinated globin from Spisula solidissima

High energy consumption in the nervous system requires a continuous supply of O2. This role is assisted by proteins from the globin super-family in the nerve cells of invertebrates, where ‘nerve hemoglobins’ (nHbs) are mainly present at mM concentrations and exhibit oxygen affinities comparable to those of vertebrate myoglobins. To gain insight into the structural bases of this function, we report the crystal structure of nHb from the Atlantic surf clam Spisula solidissima (SsHb), previously suggested to display a bis-histidyl hexa-coordinated heme in the deoxy state, high O2 affinity, and ligand binding cooperativity when assayed in situ. The crystallized protein forms a dimer through packing of a 4-helix bundle involving helices E and F of each subunit. The SsHb ‘classic’ globin fold displays bis-histidyl (His71(E7) and His103(F8)) hexa-coordination of the heme-Fe atom, with structural and dynamics variations found in the inter-helix hinge regions. Molecular Dynamics simulations of both monomeric and dimeric species in the bis-histidyl hexa-coordinated, deoxy penta-coordinated, and O2-bound hexa-coordinated states reveal distinct structural rearrangements at the interface between subunits in the dimer; these would affect the magnitude of the conformational fluctuations observed between monomer and dimer, and the topology of cavities within the protein matrix and at the interface. These results point to a distal site opening mechanism allowing access of the exogenous ligand to the heme and cast hypotheses on the dimer interface structural and dynamic properties that may support ligand binding cooperativity in dimeric SsHb.-

Interactive Effects of Climate Change‐Induced Range Shifts and Wind Energy Development on Future Economic Conditions of the Atlantic Surfclam Fishery

AbstractRising water temperatures along the northeastern U.S. continental shelf have resulted in an offshore range shift of the Atlantic surfclam Spisula solidissima to waters still occupied by ocean quahogs Arctica islandica. Fishers presently are prohibited from landing both Atlantic surfclams and ocean quahogs in the same catch, thus limiting fishing to locations where the target species can be sorted on deck. Wind energy development on and around the fishing grounds will further restrict the fishery. A spatially explicit model of the Atlantic surfclam fishery (Spatially Explicit Fishery Economics Simulator) has the ability to simulate the consequences of fishery displacement due to wind energy development in combination with fishery and stock dynamics related to the species' overlap with ocean quahogs. Five sets of simulations were run to determine the effect of varying degrees of species overlap due to Atlantic surfclam range shifts in conjunction with fishing constraints due to wind farm development. Simulations tracked changes in relative stock status, fishery performance, and the economic consequences for the fishery. Compared to a business‐as‐usual scenario, all scenarios with less‐restrictive fishing penalties due to species overlap exhibited higher raw catch numbers but also greater reductions in revenue and increases in cost after the implementation of wind farms. This analysis serves to demonstrate the response of the Atlantic surfclam fishery to combined pressures from competing ocean uses and climate change and emphasizes the potential for economic disruption of fisheries as climate change interacts with the evolution of ocean management on the continental shelf.

Potential Repercussions of Offshore Wind Energy Development in the Northeast United States for the Atlantic Surfclam Survey and Population Assessment

AbstractThe Atlantic surfclam Spisula solidissima fishery, which spans the U.S. Northeast continental shelf, is among the most exposed to offshore wind energy development impacts because of the overlap of fishing grounds with wind energy lease areas, the hydraulic dredges used by the fishing vessels, and the location of vessel home ports relative to the fishing grounds. The Atlantic surfclam federal assessment survey is conducted using a commercial fishing vessel in locations that overlap with the offshore wind energy development. Once wind energy turbines, cables, and scour protection are installed, survey operations within wind energy lease areas may be curtailed or eliminated due to limits on vessel access, safety requirements, and assessment survey protocols. The impact of excluding the federal assessment survey from wind energy lease areas was investigated using a spatially explicit, agent‐based modeling framework that integrates Atlantic surfclam stock biology, fishery captain and fleet behavior, and federal assessment survey and management decisions. Simulations were designed to compare assessment estimates of spawning stock biomass (SSB) and fishing mortality (F) for scenarios that excluded the survey from (1) wind energy lease areas or (2) wind energy lease areas and potential wind energy lease areas (“call areas”). For the most restricted scenario, the simulated stock assessment estimated 17% lower SSB relative to an unrestricted survey, placing it below the SSB target. The simulated F increased by 7% but was still less than the accepted F threshold. Changes in biological reference points were driven by the inability to access the Atlantic surfclam biomass within the wind energy lease areas. Deviations in reference points reflected the proportion of the population excluded from the survey. Excluding the Atlantic surfclam assessment surveys from the regions designated for offshore wind development can alter long‐term stock assessments by increasing uncertainty in metrics that are used to set fishing quotas.

Exploring the Feasibility of Selectively Breeding Farmed Atlantic Surfclams Spisula solidissima for Greater Heat Tolerance

AbstractBivalve aquaculture is an important and rapidly expanding sector in global food production, yet climate change presents numerous challenges to its continued expansion. The Atlantic surfclam Spisula solidissima is emerging as an attractive alternate species for aquaculturists across the northeastern United States since it is native, grows rapidly, and complements the region’s established farming framework. However, the species is vulnerable to prolonged high temperature conditions, an issue that will be exacerbated by rising ocean temperatures and is particularly problematic on shallow coastal farms. In this study, we evaluated the response of adult farmed Atlantic surfclams to heat stress after juvenile exposure and the ability for heat tolerance to be passed to subsequent generations. We found that when juvenile Atlantic surfclams were exposed to prolonged lethal temperatures, the adult survivors withstood subsequent heat stress for significantly longer than individuals not exposed to lethal temperatures as juveniles. We also found that selective breeding enhanced heat tolerance in first‐generation Atlantic surfclam progeny. Moreover, growth of the heat‐selected progeny was not significantly different from that of control Atlantic surfclams. Although more research on this topic is necessary, this work suggests that selective breeding may be a viable strategy for enhancing survival of cultivated bivalves vulnerable to heat stress.

Energetic response of Atlantic surfclam Spisula solidissima to ocean acidification

In this study, we assessed the Atlantic surfclam (Spisula solidissima) energy budget under different ocean acidification conditions (OA). During 12 weeks, 126 individuals were maintained at three different ρCO2 concentrations. Every two weeks, individuals were sampled for physiological measurements and scope for growth (SFG). In the high ρCO2 treatment, clearance rate decreased and excretion rate increased relative to the low ρCO2 treatment, resulting in reduced SFG. Moreover, oxygen:nitrogen (O:N) excretion ratio dropped, suggesting that a switch in metabolic strategy occurred. The medium ρCO2 treatment had no significant effects upon SFG; however, metabolic loss increased, suggesting a rise in energy expenditure. In addition, a significant increase in food selection efficiency was observed in the medium treatment, which could be a compensatory reaction to the metabolic over-costs. Results showed that surfclams are particularly sensitive to OA; however, the different compensatory mechanisms observed indicate that they are capable of some temporary resilience.

Persistence of Hydraulic Dredge Tracks Following Surfclam Harvesting in Shallow Water

Hydraulic dredges used for bivalve harvest are known to create immediate biological and physical changes to the substrate, but the rate of recovery is often site specific and habitat specific. Hydraulic dredging for the Atlantic surfclam Spisula solidissima (Dillwyn, 1817) occurred off Provincetown, MA, from November 2014 through April 2015. Acoustic surveys following the dredge activity were conducted in 2015 (June–August) with a phase-measuring sidescan sonar, yielding colocated sidescan backscatter and swath bathymetry. Dredge tracks were documented in 7.9% (402,309 m2) of the 5.1 km2 surveyed. The survey area was divided into 10 × 10 m grid cells, and track density was calculated within each grid by the aggregated count of dredge tracks within each grid cell. The resulting track densities ranged between 0% and 53%. On October 23, 2017, 875 days after the 2015 hydraulic clamming season, a subset (1.05 km2 ∼20%) of the same area was acoustically surveyed. The 2017 survey (1.05 km2) revealed that dredge tracks covered a total area of 9,784 m2 at a density of 0%–24%. Initial areas (2015) with dredge track density greater than 10% had not fully recovered in 2017, and the rate of dredge tracks remaining was proportional to disturbance (linear regression; r2 = 0.95; F = 110.6; df = 1,7; P < 0.001; SE = 0.206). The adjacent dynamic shoreline and the persistence of dredge tracks reinforce the idea that nearshore energy regimes should not be assumed based solely on more visible shoreline processes.

Changes in the spatial distribution and anatomy of a range shift for the Atlantic surfclam Spisula solidissima in the Mid-Atlantic Bight and on Georges Bank

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 620:77-97 (2019) - DOI: https://doi.org/10.3354/meps12964 Changes in the spatial distribution and anatomy of a range shift for the Atlantic surfclam Spisula solidissima in the Mid-Atlantic Bight and on Georges Bank Jeremy R. Timbs1,*, Eric N. Powell1, Roger Mann2 1Gulf Coast Research Laboratory, The University of Southern Mississippi, Ocean Springs, MS 39564, USA 2Virginia Institute of Marine Sciences, The College of William and Mary, Gloucester Point, VA 23062-1346, USA *Corresponding author: jeremy.timbs@dmr.ms.gov ABSTRACT: The Atlantic surfclam Spisula solidissima supports one of the largest fisheries on the US northeast coast. Using ~30 yr of data from surfclam stock surveys, variance-to-mean ratios (VtMRs) were calculated both temporally and spatially for a range of surfclam size classes to determine the degree of patchiness. The VtMR declined from the 1980s to present in all regions (offshore Delmarva, New Jersey, Long Island, Southern New England, Georges Bank); however, VtMR rose with increasing clam size. Taylor’s power law (TPL) analysis corroborated the VtMR; the surfclam is highly patchy across its range. The surfclam’s proclivity for a patchy distribution varied regionally. Regions supporting the bulk of the stock were characterized by significantly higher degrees of patchiness and exhibited a higher exponent for the TPL. A species distribution function model corroborated findings of declining patchiness over time, supporting the hypothesis that warming of Mid-Atlantic continental shelf bottom waters is both driving the surfclam into new habitat and extirpating it from nearshore and southern areas. Size-dependent and temporal trends in VtMRs and temporal relative stability in TPL suggest that range expansion is conduced by regional settlement of larvae, followed by biased mortality in suboptimal habitats. This biased mortality ultimately re-establishes the increased patchiness characteristic of larger animals but also predisposes the species to a rapid range shift. Declining VtMRs over time may be a symptom of range expansion along the leading range boundary that has increased the proportion of newly occupied habitat without mature patch characteristics while, at the same time, range recession has removed the older mature patches along the range’s trailing edge. KEY WORDS: Patchy distribution · Larval transport · Ocean warming · Larval connectivity · Range shift Full text in pdf format PreviousNextCite this article as: Timbs JR, Powell EN, Mann R (2019) Changes in the spatial distribution and anatomy of a range shift for the Atlantic surfclam Spisula solidissima in the Mid-Atlantic Bight and on Georges Bank. Mar Ecol Prog Ser 620:77-97. https://doi.org/10.3354/meps12964 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 620. Online publication date: June 18, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Assessment of the Relationship of Stock and Recruitment in the Atlantic Surfclam Spisula solidissima in the Northwestern Atlantic Ocean

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.

Tools for Estimating Surplus Production andFMSYin Any Stock Assessment Model

Abstract Surplus-production calculations can be made in any stock assessment model that includes catch data and that estimates biomass. Maximum sustainable yield (MSY) reference points can also be estimated if there are sufficient data. The “external” method estimates production model parameters after the assessment model is fitted. External calculations are simple and useful; we recommend that they be done routinely. The “internal” method fits a more complicated assessment model and a surplus-production model simultaneously. It includes the external and “all-measurement-error” modeling methods (e.g., ASPIC) as special cases. External MSY estimates for Atlantic surfclam Spisula solidissima off northern New Jersey, cowcod Sebastes levis in the Southern California bight, and yellowtail flounder Pleuronectes ferrugineus on Georges Bank and internal MSY estimates for northern Atlantic surfclam were similar to conventional estimates. Surplus-production calculations and both internal and external modeling appro...

Discovery of 5R-lipoxygenase activity in oocytes of the surf clam, Spisula solidissima

Arachidonic acid and 5-hydroxyeicosatetraenoic acid (5-HETE) are reported to induce reinitiation of meiosis in oocytes of the surf clam Spisula sachalinensis from the Sea of Japan (Varaksin et al., Comp. Biochem. Physiol. 101C, 627–630 (1992). As the Atlantic surf clam Spisula solidissima is a commonly used model for the study of meiosis reinitiation, we examined these cells for the possible occurrence of lipoxygenases and for the bioactivity of the products. Incubation of [ 14C]arachidonic acid with homogenates of S. solidissima oocytes led to the formation of two major metabolites: 5R-HETE, a novel lipoxygenase product, and 8R-HETE. The products were identified by HPLC, uv spectroscopy, and GC-MS. The corresponding hydroperoxy fatty acids, the primary lipoxygenase products, were isolated from incubations of ammonium sulfate fractionated oocyte cytosol. Arachidonic and eicosapentaenoic acids were identified as constituents of S. solidissima oocyte lipids and the free acids were equally good lipoxygenase substrates. We examined the activity of C18 and C20 polyunsaturated fatty acids and their lipoxygenase products on meiosis reinitiation in Spisula solidissima oocytes, using serotonin and ionophore A23187 as positive controls. The fatty acids and their derivatives were inactive. We conclude that in the surf clam, (as in starfish), there are responding and non-responding species in regard to the maturation-inducing activity of the oocyte lipoxygenase products, and that the lipoxygenase has another, as yet uncharacterized, function in oocyte physiology.

Fecundity of the Southern Atlantic SurfclamSpisula solidissima similis

Abstract Fecundity estimates for two groups of the southern Atlantic surfclam Spisula solidissima similis, a subspecies of the Atlantic Surfclam S. solidissima, from St. Catherines Sound, Georgia, were determined in laboratory spawning trials. For 1-year-old clams ranging in shell length from 26 to 50 mm, egg production per female ranged from 0.14 million to 13 million eggs. The House Creek group produced a greater mean number of eggs per female (4.8 × 106 versus 1.7 × 106) and spawned 2.8 times more than a St. Catherines Sound group. Overall, eggs from the House Creek group (mean, 59.1 μm) were significantly larger (P < 0.0001) than eggs (mean, 57.4 um) from the St. Catherines Sound group. Although small in size, 1-year-old southern Atlantic surfclams can produce sufficient numbers of eggs per female to be used as broodstock for the development of an aquacultural fishery for this subspecies.

DIETS OF THE BRACHYURAN CRABS CANCER IRRORATUS, C. BOREALIS, AND OVALIPES OCELLATUS IN THE NEW YORK BIGHT

ABSTRACT The stomach contents of 146 Atlantic rock crabs, Cancer irroratus, 87 Jonah crabs, Cancer borealis, and 47 northern lady crabs, Ovalipes ocellatus collected from the area surrounding the former 12-Mile Sewage Sludge Dumpsite in the New York Bight were analyzed. In the dumpsite area, all 3 species principally ate, as quantified by frequency of occurrence and volume, polychaetes, especially Pherusa affinis, as well as mollusks (including squid), crustaceans, fish, and echinoderms. The proportion of mollusks by volume was significantly less in the diet of C. irroratus than in the other 2 species. Many of the taxa in the diets of the 3 species of crabs were among the dominant macrobenthic taxa, as determined by concurrent grab samples at 3 of the stations. At those stations, crustaceans were positively selected by C. irroratus, while cnidarians and rhynchocoels were not selected. In addition, the stomach contents of 27 O. ocellatus from False Hook Channel, a nearby shallower, sandy habitat, were examined. The diet of O. ocellatus at this site was > 80% mollusks by volume, and the most frequently occurring prey was the Atlantic surf clam Spisula solidissima.

Age and growth rate determinations for the Atlantic surf clam Spisula solidissima (Bivalvia: Mactracea), based on internal growth lines in shell cross-sections

Marked and recovered surf clams, Spisula solidissima Dillwyn, from Virginia (USA) deposited one internal growth line during a period of 11/2 years, probably in response to spawning during late summer. We have used these annual growth lines to make growth curves for two samples of New Jersey (USA) clams, one from inshore (1.8 km from shore, 15 m deep), the other from offshore (17.5 km from shore, 28 m deep) waters. The offshore and inshore clams grow at approximately the same rate until Age 3 years, after which time the growth rates differ, as does the ultimate lifespan; the offshore clams grow more rapidly and attain a greater age — up to 31 years. Comparison of our growth curves with other published curves revealed a close correspondence to a curve which was based on a study of growth over a 5-year period. Curves based on external growth lines probably underestimate growth rate in early life and overestimate it in later years.