Enhancing Seed Availability For the Hard Clam (Mercenaria mercenaria) Aquaculture Industry By Applying Remote Setting Techniques

The goal of this study was to test a technology that may help ensure a reliable and consistent supply of high quality and inexpensive clam seed to growers, thus fostering an emerging aquaculture industry by eliminating a seed shortage that limits sustainability. The overall objectives were to develop, test and demonstrate technical procedures and determine the financial feasibility of transferring remote setting technology from the Pacific Northwest molluscan shellfish industry to the hard clam aquaculture industry in Florida. (PDF has 44 pages.)

Annotated bibliography II of the hard clam Mercenaria mercenaria

In this era of proliferating scientific information it is difficult to keep up with the literature, even in one's own field. Review articles are helpful in summarizing the status of knowledge. In oyster biology, several such published reviews have been of great help to working scientists. The outstanding contributions that come to' mind are those by Baughman (1948), Korringa (1952), Joyce (1972), Breisch and Kennedy (1980), and Kennedy and Breisch (198 I). If done well, such compilations serve as checkpoints, eliminating or vastly reducing the need to consult the literature in detail. On Long Island, New York, where the hard clam Mercenaria mercenaria is the major commercial resource, we have felt the need for some time for a compendium of knowledge on this important mollusk. Several years ago my secretary, students, and I began to gather materials for an annotated bibliography. We have already published a collection of 2233 titles (McHugh et al. 1982), nearly all accompanied by abstracts, and in this publication we have added another 460. The experience has been rewarding. We have been surprised at the extent of the literature, much of it only remotely related to the shellfish industry itself, but nevertheless throwing light on the biology, physiology, and many other aspects of the scientific knowledge of hard clams. The following bibliography is divided into three parts. Part I comprises the bulk of the bibliography, while Parts 2 and 3 contain additional titles that we decided to include during editing, submission, and approval of the manuscript for publication. All three parts are indexed together, however. We also reexamined those titles in the previous bibliography (McHugh et al. 1982) which did not include abstracts. These are included in Parts 2 and 3 of this bibliography. Most of these contained no specific reference to Mercenaria mercenaria. A few searches were terminated for various reasons. (PDF file contains 66 pages.)

The effect of organotin and copper sulfate on the late development and presettlement behavior of the hard clam Mercenaria mercenaria

The effect of organotin compounds and copper, commonly used as antifouling agent, were studied on Mercenaria mercernaria larvae. They were reared under usual hatchery conditions until they reached 190 um in diameter. The larvae were subjected to four compounds, tributylin chloride (TBT), monobutyltin chloride (MBT), trimethyltin chloride (TMT), cupric sulfate (CuSo4) plus control. Mortality was measured at 24, 48 h, and 96h. Behavioral and/or metamorphic changes were recorded in triplicate at 24-48 and 96 h. The appearance in swimming larvae of a functional foot was considered a sign of competence to set and was recorded as a "pediveliger". Swimming larvae were considered as larvae that have not yet reached their total development and they were recorded as "swimming". Larvae that did not show foot or swimming activity and were static but alive on the bottom were recorded as "bottom". TBT was found to completely inhibit swimming activity at sublethal concentrations throughout the period of observation. Copper and MBT inhibited swimming from 48 h, TMT did not inhibit swimming activity at any of the times recorded. The four compounds ranked in order of decreasing toxicity were TBT>TMT>CU>MBT.

A Decline in Starfish, Asterias forbesi, Abundance and a Concurrent Increase in Northern Quahog, Mercenaria mercenaria, Abundance and Landings in the Northeastern United States

The abundance of the common starfish, Asterias forbesi, fluctuates widely over time. The starfish is a predator of pre-recruit northern quahogs, Mercenaria mercenaria. During the 1990’s, starfish became scarce in Raritan Bay and Long Island Sound. Quahog populations concurrently erupted in abundance and quahog landings have risen sharply in both locations. The extensive scale of this observation would seem to imply a cause and effect; at the least, both populations may be responding differently to a large scale exogenous factor.

INVOLVEMENT OF CA(2+) SIGNALING PATHWAY DURING OOCYTE MATURATION OF THE NORTHERN QUAHOG MERCENARIA MERCENARIA

In many molluses, it has been found that Ca2+ signaling pathway is involved in the resumption of meiotic maturation in oocytes. To better understand the possible role of Ca2+ signaling pathway in regulating meiotic maturation in oocytes of the northern quahog Mercenaria mercenaria, free extracellular Ca2+, A23187 (calcium ionophore), verapamil (calcium channel blocker), and trifluoperazin (calmodulin antagonist) were used to incubate oocytes or serotonin-induced oocytes by pharmacological methods. Results show that extracellular Ca2+ (50 similar to 200 mM) and A23187 (1 similar to 10 mu M) can stimulate the meiotic maturation. In addition, verapamil (1 similar to 100 mu M) and trifluoperazin (10 similar to 1,000 mu M) could inhibit serotonin-induced oocyte maturation. Therefore, Ca2+ is essential for the reinitiation of meiotic maturation in oocytes of the northern quahog. Moreover, an increase i [Ca2+]i can promote meiotic maturation.

Chromosomal mapping of major ribosomal rRNA genes in the hard clam (Mercenaria mercenaria) using fluorescence in situ hybridization

Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the hard clam (Mercenaria mercenaria Linnaeus) using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos. Internal transcribed spacers (ITS) between major RNA genes were amplified and used as FISH probes. The probes were labeled with digoxigenin-11-dUTP by polymerase chain reaction and detected with fluorescein-labeled anti-digoxigenin antibodies. FISH with the ITS probes produced two to four signals per nucleus or metaphase. M. mercenaria had a haploid number of 19 chromosomes with a karyotype of seven metacentric, four metacentric or submetacentric, seven submetacentric, and one submetacentric or subtelocentric chromosomes (7M + 4M/SM + 7SM + 1SM/ST). Two ITS loci were observed: one located near the centromere on the long arm of Chromosome 10 and the other at the telomere of the short arm of Chromosome 12. FISH signals on Chromosome 10 are strong and consistent, while signals on Chromosome 12 are variable. This study provides the first karyotype and chromosomal assignment of the major RNA genes in M. mercenaria. Similar studies in a wide range of species are needed to understand the role of chromosomal changes in bivalve evolution.

Seawater carbonate chemistry and biological processes of bivalve shellfish Mercenaria mercenaria and Argopecten irradians during experiments, 2011

The combustion of fossil fuels has enriched levels of CO2 in the world's oceans and decreased ocean pH. Although the continuation of these processes may alter the growth, survival, and diversity of marine organisms that synthesize CaCO3shells, the effects of ocean acidification since the dawn of the industrial revolution are not clear. Here we present experiments that examined the effects of the ocean's past, present, and future (21st and 22nd centuries) CO2concentrations on the growth, survival, and condition of larvae of two species of commercially and ecologically valuable bivalve shellfish (Mercenaria mercenariaand Argopecten irradians). Larvae grown under near preindustrial CO2concentrations (250 ppm) displayed significantly faster growth and metamorphosis as well as higher survival and lipid accumulation rates compared with individuals reared under modern day CO2 levels. Bivalves grown under near preindustrial CO2 levels displayed thicker, more robust shells than individuals grown at present CO2 concentrations, whereas bivalves exposed to CO2 levels expected later this century had shells that were malformed and eroded. These results suggest that the ocean acidification that has occurred during the past two centuries may be inhibiting the development and survival of larval shellfish and contributing to global declines of some bivalve populations.

Glorias de la beata Maria Ana de Jesus mercenaria descalza : publicadas en las solemnes fiestas que a su beatificación celebró el colegio de su orden en la ciudad de Salamanca, año de 1783 /

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Seawater carbonate chemistry and survival of mollusks: Mercenaria mercenaria, Argopecten irradians, and Crassostrea virginica during experiments, 2009

We present experiments that examined the metamorphosis, growth, and survivorship of larvae from three species of commercially and ecologically valuable shellfish (Mercenaria mercenaria, Argopecten irradians, and Crassostrea virginica) at the levels of CO2 projected to occur during the 21st century and beyond. Under CO2 concentrations estimated to occur later this century (~66 Pa, 650 ppm), M. mercenaria and A. irradians larvae exhibited dramatic declines (>50%) in survivorship as well as significantly delayed metamorphosis and significantly smaller sizes. Although C. virginica larvae also experienced lowered growth and delayed metamorphosis at ~66 Pa CO2, their survival was only diminished at ~152 Pa CO2. The extreme sensitivity of larval stages of shellfish to enhanced levels of CO2 indicates that current and future increases in pelagic CO2 concentrations may deplete or alter the composition of shellfish populations in coastal ecosystems.

Seawater carbonate chemistry, calcification and shell size of hard clam Mercenaria mercenaria during experiments, 2011

Increasing atmospheric carbon dioxide threatens to decrease pH in the world's oceans. Coastal and estuarine calcifying organisms of significant ecological and economical importance are at risk; however, several biogeochemical processes drive pH in these habitats. In particular, coastal and estuarine sediments are frequently undersaturated with respect to calcium carbonate due to high rates of organic matter remineralization, even when overlying waters are saturated. As a result, the post-larval stages of infaunal marine bivalves must be able to deposit new shell material in conditions that are corrosive to shell. We measured calcification rates on the hard clam, Mercenaria spp.,in 5 post-larval size classes (0.39, 0.56, 0.78, 0.98, and 2.90 mm shell height) using the alkalinity anomaly method. Acidity of experimental water was controlled by bubbling with air-CO2 blends to obtain pH values of 8.02, 7.64, and 7.41, corresponding to pCO2 values of 424, 1120, and 1950 µatm. These pH values are typical of those found in many near-shore terrigenous marine sediments. Our results show that calcification rate decreased with lower pH in all 5 size classes measured. We also found a significant effect of size on calcification rate, with the smaller post-larval sizes unable to overcome dissolution pressure. Increased calcification rate with size allowed the larger sizes to overcome dissolution pressure and deposit new shell material under corrosive conditions. Size dependency of pH effects on calcification is likely due to organogenesis and developmental shifts in shell mineralogy occurring through the post-larval stage. Furthermore, we found significantly different calcification rates between the 2 sources of hard clams we used for these experiments, most likely due to genotypic differences. Our findings confirm the susceptibility of the early life stages of this important bivalve to decreasing pH and reveal mechanisms behind the increased mortality in post-larval juvenile hard clams related to dissolution pressure, that has been found in previous studies.