Polinices Predation Patterns and Mercenaria Morphology Models

DeAngelis et al. (1985) have described a model of the evolutionary response of bivalve prey to size-selective naticid snail predation. The model analyzed the allocation of bivalve energy among reproduction, overall growth in size, and supplementary growth in shell thickness (p. 818). Using parameter values for Polinices duplicatus as the predator and Mercenaria mercenaria as the prey, the model predicted three optimal strategies for bivalves faced with naticid predation: (1) delayed reproduction with energy diverted into rapid growth in order to reach a size refuge; (2) early reproduction, possibly with some extra shell thickness; and (3) greatly increased shell thickness for deterring predator attacks. This model and an earlier one (DeAngelis et al. 1984) are elaborations on a general qualitative model for bivalve prey (Seed and Brown 1978). [excerpt

Mussels with Meat: Bivalve Tissue-Shell Radiocarbon Age Differences and Archaeological Implications

Local reservoir ages are often estimated from the difference between the radiocarbon ages of aquatic material and associated terrestrial samples for which no reservoir effect is expected. Frequently, the selected aquatic material consists of bivalve shells that are typically well preserved in the archaeological record. For instance, large shell middens attest to the importance of mussel consumption at both coastal and inland sites. However, different physiological mechanisms associated with tissue and shell growth may result in differences in reservoir effects between the surviving component (shell) and the component relevant to dietary reservoir effects in consumers (tissue). The current study examines bivalve tissue-shell age differences both from freshwater and marine contexts close to archaeological sites where human consumption of mollusks has been attested. Results exhibited significant 14C age differences between bivalve tissue and shell in a freshwater context. In a marine context, no significant bivalve tissue-shell age differences were observed. The results also showed that riverine and lacustrine shells show large and variable freshwater reservoir effects. The results have important implications for establishing local reservoir effects especially in a freshwater environment. For good a priori knowledge of expected 14C differences in organic and inorganic water, carbon is thus necessary. Furthermore, the high variability in freshwater shell 14C ages implies the need for representative sampling from the archaeological record

Travel report Mauritania bivalve Molluscs october 2008

During the last four years Mauritania has been working on the completion of a Food Safety Program of Bivalve Mollusks, in order to obtain an export approval by the Europe Union. During the preparations for an inspection by the FVO (Food and Veterinary Office) no fisheries or production activities for Bivalve Mollusks occurred in Mauritania. The aim of the mission was to perform a pre-assessment on the status of the Bivalve Food Safety program in Mauritania. The pre-inspection was carried out in order to prepare Mauritania for the upcoming Food and Veterinary Office (FVO) inspection, planned for the second semester of 2008 or the beginning of 2009

Pre-inspection Mauritania Bivalve Mollusks Food Safety April 20-24th 2008

Mauritania is working on the completion of a Food Safety Program for Bivalve Mollusks, in order to be obtain an export approval by the Europe Union for the last 4 years (and before). For the second semester 2008 the FVO has programmed a veterinary inspection for the on bivalve mollusks. In order to prepare themselves for the veterinary inspection the competent authority of Mauritania (ONISPA) has requested Wageningen IMARES for a pre-inspection of the Mauritanian system. The pre-inspection was performed during the period of 20-24 April in Mauritania (Nouakchott and Nouadhibou)

Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)

Although the bivalve dredge used on the Algarve coast (southern Portugal) is highly selective for the target species, in some periods of the year the bycatch can exceed the catch of the commercial species. The present study aimed to quantify the bycatch and discards, estimate damage and mortality, and propose management measures to minimize discards and mortality. A total of 15 fishing surveys (60 tows) were performed using two types of dredges (“DDredge” targeting Donax trunculus and “SDredge” targeting Spisula solida and Chamelea gallina). Of the 85257 individuals (392.4 kg) of 52 taxa that were caught, 73.4% belonged to the target species, 22.1% to commercially undersized target species and 4.5% to bycatch species. Bycatch rates were lower for SDredge (13.5% in number and 6.3% in weight) than for DDredge (46.0% in number and 32.9% in weight). Damage and mortality rates were also lower using SDredge (1.3% and 1.0% of the total catches, respectively) than using DDredge (4.0% and 2.8% of the total catches). Survival experiments revealed the diverse vulnerability of the taxa and confirmed the influence of the damage score on the mortality rate. The results gathered in the present study encourage the adoption of a bycatch reduction device to reduce both direct and indirect mortality.This study was performed within the framework of the research project “Science Technology and Society Initiative to Minimize Unwanted Catches in European Fisheries (MINOUW)” funded by the Research and Innovation Action (RIA) of the EU Horizon 2020 programme.info:eu-repo/semantics/publishedVersio

Faunal change in Cretaceous endemic shallow-marine bivalve genera/subgenera of the northeast Pacific

Endemic shallow-marine Cretaceous bivalves in the northeast Pacific region (NEP), extending from southwestern Alaska to the northern part of Baja California Sur, Mexico, are tabulated and discussed in detail for the first time. Twenty-three genera/subgenera are recognized. Their first appearance was in the Valanginian, and their biodiversity continued to be very low during the rest of the Early Cretaceous. The bivalves of the middle Albian Alisitos Formation in northern Baja California are excluded because they did not live in the NEP. The highest number (13) of NEP endemic bivalve genera/subgenera occurred during the Turonian, which was the warmest time of the Cretaceous. At the Turonian/Coniacian boundary, when cooler waters migrated southward, there was a moderate dropoff in endemics that persisted until an origination event near the beginning of the early Maastrichtian, when 11 were present. Five of the 11 were present also during the Turonian, but the others were newcomers. Only three survived the turnover associated with the “Middle Maastrichtian Event” (MME), and none survived the K/Pg boundary mass-extinction event

Disseminated neoplasia in blue mussels, Mytilus galloprovincialis, from the Black Sea, Romania

Disseminated neoplasia, also called leukemia or hemic neoplasia, has been detected in 15 species of marine bivalve mollusks worldwide. The disease is characterized by the presence of single anaplastic cells with enlarged nuclei and sometimes frequent mitosis, in hemolymph vessels and sinuses. The neoplastic cells gradually replace normal hemocytes leading to the increased mortality of animals. The neoplasia reaches epizootic prevalences in blue mussels, Mytilus trossulus, in some areas, whereas prevalences in Mytilus edulis are generally very low. Mytilus galloprovincialis was suggested to be resistant to the disease although very low prevalences were documented from Spain in the Atlantic Ocean and Italy in the Mediterranean Sea. A case of disseminated neoplasia was discovered in M. galloprovincialis from among 200 specimens studied from the coast of the Romanian Black Sea. Histological preparation revealed the presence of large anaplastic cells with lobed nuclei. This observation extends the geographic range of marine bivalve mollusks with disseminated neoplasia to include the Black Sea

Results of a study of bivalve molluscs of central Asia = Итоги исследования двустворчатых моллюсков Центральной Азии

The article is devoted to many years’ research (1972 - 2001) of bivalve mollusks of Central Asia. It is established that it is inhabited by 51 species of molluscs belonging to 16 genera, 8 families and three orders. Among them 13 species and 1 subgenus are described as new for science. Their ecology, distribution by basin types, byotopes, life forms and economic significance have been studied

Oyster RNA-seq data support the development of Malacoherpesviridae genomics

The family of double-stranded DNA (dsDNA) Malacoherpesviridae includes viruses able to infect marine mollusks and detrimental for worldwide aquaculture production. Due to fast-occurring mortality and a lack of permissive cell lines, the available data on the few known Malacoherpesviridae provide only partial support for the study of molecular virus features, life cycle, and evolutionary history. Following thorough data mining of bivalve and gastropod RNA-seq experiments, we used more than five million Malacoherpesviridae reads to improve the annotation of viral genomes and to characterize viral InDels, nucleotide stretches, and SNPs. Both genome and protein domain analyses confirmed the evolutionary diversification and gene uniqueness of known Malacoherpesviridae. However, the presence of Malacoherpesviridae-like sequences integrated within genomes of phylogenetically distant invertebrates indicates broad diffusion of these viruses and indicates the need for confirmatory investigations. The manifest co-occurrence of OsHV-1 genotype variants in single RNA-seq samples of Crassostrea gigas provide further support for the Malacoherpesviridae diversification. In addition to simple sequence motifs inter-punctuating viral ORFs, recombination-inducing sequences were found to be enriched in the OsHV-1 and AbHV1-AUS genomes. Finally, the highly correlated expression of most viral ORFs in multiple oyster samples is consistent with the burst of viral proteins during the lytic phase

Long-Term Trends in Calcifying Plankton and pH in the North Sea

Relationships between six calcifying plankton groups and pH are explored in a highly biologically productive and data-rich area of the central North Sea using time-series datasets. The long-term trends show that abundances of foraminiferans, coccolithophores, and echinoderm larvae have risen over the last few decades while the abundances of bivalves and pteropods have declined. Despite good coverage of pH data for the study area there is uncertainty over the quality of this historical dataset; pH appears to have been declining since the mid 1990s but there was no statistical connection between the abundance of the calcifying plankton and the pH trends. If there are any effects of pH on calcifying plankton in the North Sea they appear to be masked by the combined effects of other climatic (e.g. temperature), chemical (nutrient concentrations) and biotic (predation) drivers. Certain calcified plankton have proliferated in the central North Sea, and are tolerant of changes in pH that have occurred since the 1950s but bivalve larvae and pteropods have declined. An improved monitoring programme is required as ocean acidification may be occurring at a rate that will exceed the environmental niches of numerous planktonic taxa, testing their capacities for acclimation and genetic adaptation