Nucula Sulcata Research Articles

Distribution of soft-bottom benthic molluscs in the Gulf of Oran (Western Algeria)

A total of 46 samples were taken in the softbottom of the Gulf of Oran, in order to study the nature of the sediments and the spatial distribution of the mollusc communities. As a result of sampling in the study area, at depth range (30 m -106 m), a total of 29 species were identified, included in two classes: Gastropoda and Bivalvia. The use of multi-variate statistical analyzes, as well as particle size analysis, made it possible to identify the main mollusc communities. Six mollusc communities were defined from faunistic and sedimentologic affinities. The malacological fauna of the Gulf of Oran is dominated by Saccella commutata (33.33%), Limatula subauriculata (20.83%) and Nucula sulcata (20.83%). The main ecological stocks are mixicole and coastal detritus species. The malacofauna of the Gulf of Oran is scarce and less diversified due to the nature of the soft bottoms (sand and gravel) and the absence of terrigenous inputs.

Biodiversity of bivalves in the mangrove ecosystem in Kampung Jawa, Banda Aceh

Mangrove ecosystem as a feeding ground contributes to habitat complexity and diversity of the macrofauna, while bivalves are dominant in this ecosystem. The diversity of Bivalve had influenced by habitat conditions that have an impact on ecosystem stability. This research purposed to assess diversity and species abundance of bivalve in Kampung Jawa. The parameters analyzing included density, diversity index, and the species of a dominant index. The research was conducted in March 2020 at five stations with purposive sampling method. There are 8 species of Bivalve found in this area. The Bivalve species found are Nucula sulcata, Anadara granos, Glycymeris Modesta, Anadara transversa, Brachidontes granulatus, Anadara nodifera, Cucullaea Labiatae, and Glycymeris glycymeris. The analysis showed that Anadara transverse species was the most abundant with a density value 5.2 ind/m2. Diversity values from the five stations have obtained at 0.69 - 1.37 with a medium diversity category indicated that the variation of Bivalve species is quite diverse.

Epibenthic assemblages in the Celtic Sea and associated with the Jones Bank

The epibenthic assemblages in the Celtic Sea are described from the catches from 2m beam trawl surveys undertaken from 2000 to 2009. During this period 154 samples were collected. The most ubiquitous species in the study area were the natantid shrimps Processa spp. and Crangon allmanni, the hermit crabs Pagurus prideaux and Anapagurus laevis, sand star Astropecten irregularis and spotted dragonet Callionymus maculatus. Multivariate community analyses indicated that catches (numbers per tow) were distributed across six assemblages, two of which were predominant in the study area. Most catches were attributed to either a ‘shelf edge assemblage‘, which was widespread in deeper waters (114–423m water depth) or an ‘outer shelf assemblage’ that occurred across much of the Celtic Sea north of 49°N in waters 49–175m deep. The dominant species along the edge of the continental shelf were the hormathid anemome Actinauge richardi, sea spider Pycnogonum littorale (which associated with A. richardi), Devonshire cup coral Caryophyllia smithii and the swimming crab Macropipus tuberculatus. The dominant species in the outer shelf assemblage included P. prideaux, C. allmanni, A. laevis and common starfish Asterias rubens. Stations closer to shore were relatively distinct and catches in this ‘inner shelf assemblage’ were composed primarily of an inshore fauna (e.g. Ophiura ophiura, C. allmanni and Liocarcinus holsatus). Stations in the southern part of the survey grid were also relatively distinct (‘southern Celtic Sea assemblage’), and several large echinoderms (Porania pulvillus, Stichastrella rosea and Anseropoda placenta) dominated at these sites. Three of the deepest stations were also relatively distinct, as were a group of stations in the muddy habitat of the Celtic Deep and comparable grounds elsewhere in the region, where Nucula sulcata and Alpheus glaber were characteristic. Catches on the shallower parts of the Jones Bank (and on another bank in the region) were dominated by the anemone Paraphellia expansa, with off-bank sites comprising a greater number of species. In contrast to beam trawl sampling, baited camera observations on the Jones Bank showed a greater richness of species on the shallower part of the bank, and provided information on the nocturnal feeding behaviour of scavenging isopods.

Feeding ecology of Xenoturbella bocki (phylum Xenoturbellida) revealed by genetic barcoding

The benthic marine worm Xenoturbella is frequently contaminated with molluscan DNA, which had earlier caused confusion resulting in a suggested bivalve relationship. In order to find the source of the contaminant, we have used molluscan sequences derived from Xenoturbella and compared them to barcodes obtained from several individuals of the nonmicroscopic molluscs sharing the same environment as Xenoturbella. Using cytochrome oxidase 1, we found the contaminating sequences to be 98% similar to the bivalve Ennucula tenuis. Using the highly variable D1-D2 region of the large ribosomal subunit in Xenoturbella, we found three distinct species of contaminating molluscs, one of which is 99% similar to the bivalve Abra nitida, one of the most abundant bivalves in the Gullmarsfjord where Xenoturbella was found, and another 99% similar to the bivalve Nucula sulcata. These data clearly show that Xenoturbella only contains molluscan DNA originating from bivalves living in the same environment, refuting former hypotheses of a bivalve relationship. In addition, these data suggest that Xenoturbella feeds specifically on bivalve prey from multiple species, possibly in the form of eggs and larvae.

THE HYPOXIC TOLERANCE OF THE PROTOBRANCH BIVALVE NUCULA SULCATA BRONN

Examination of the hypoxic tolerance of Nucula sulcata determined that the mean survival time under hypoxia was 9.57 d with a maximum longevity of 30 d. Comparison between the three species, N. sulcata, N. nitidosa, and N. nucleus reveals that N. sulcata is the most tolerant of hypoxia followed by N. nucleus and N. nitidosa. It is suggested that the hypoxic tolerance of the species is a reflection of the normal habitat they occupy.

Anoxic survival, oxygen consumption and haemocyanin characteristics in the protobranch bivalve Nucula sulcata Bronn

The nonsiphonate protobranch bivalve mollusc Nucula sulcata lives in sediments that may be oxygen depleted or completely anoxic. The species survives for 2 weeks in an oxygen-free environment at 10°C. Oxygen consumption is low (mean 1.57 μmol.g−1.h−1) but is within the range of infaunal lamellibranch bivalves. N. sulcata is able to maintain its rate of oxygen consumption approximately constant down to a Pc of 15–20 Torr. Like some other protobranchs, N. sulcata has haemocyanin within its haemolymph. The haemocyanin has a very high affinity for oxygen (P50 = 0.94 Torr), but oxygen binding by the pigment is noncooperative. In addition, the haemocyanin concentration and the oxygen-carrying capacity (CHCYO2 = 0.35 ± 0.08 mmol.l−1 of the haemolymph are low.

Influence of Organic Matrix on the Post-Mortem Destruction of Molluscan Shells

To examine the role of organic constituents in the destruction of calcium carbonate skeletons, we aged fresh shells of the bivalves Nucula sulcata (organic-rich nacreous aragonites with low crystallite surface areas) and Cerastoderma edule (organic-poor porcellaneous aragonites, high crystallite surface areas) under both sterile and non-sterile (microbial) conditions in aragonite-undersaturated, -saturated, and -supersaturated seawaters for periods up to 11 months. Deterioration was tracked by SEM and weight-loss, and compared to damage produced by reagents of specific effect. The same qualitative sequence of damage was observed in all tanks for both species, but rates of deterioration were $$\geq 2 \times$$ higher in microbial than in sterile tanks at a given saturation state, and were as high or higher in the microbial saturated and supersaturated tanks than in the sterile undersaturated tank. Damage to shell surfaces was limited almost entirely to loss of organic matrix, which eventually exposed and ...

Ultrastructural studies of spermatozoa in three bivalve species with notes on evolution of elongated sperm nucleus in primitive spermatozoa

AbstractSperm ultrastructure and spermiogenesis of the three bivalve species Musculus discors, Nucula sulcata, and Dreissena polymorpha have been studied. During spermatid differentiation in Musculus discors and Nucula sulcata the nucleus attains an elongated rod‐like shape. The spermatozoon from Nucula sulcata was found to have a cup‐shaped acrosome and five mitochondria surrounding two centrioles in the middle piece. The spermatozoa from Musculus discors has a long complex acrosome. From the distal centriole striated processes extend and attach to the plasma membrane. The spermatozoon of the fresh water species Dreissena polymorpha agrees in all main features with those of other invertebrate groups with external fertilization. It is thus of the primitive type with barrel‐shaped nucleus and four to five mitochondria1 spheres in the middle piece. The acrosome is a prominant, complex structure at the apex of the mature spermatozoon.A comparison of sperm ultrastructure among bivalves indicates that there is a certain correlation between the evolution of the elongated sperm nucleus and large, yolk‐rich eggs. In species with an elongated sperm nucleus the increased egg size has often led to a lecithotrophic or direct development. The elongated nucleus is a slight modification of the primitive type. There is a great variation in acrosome structure among bivalve spermatozoa, reflecting diverging functional demands at fertilization of the eggs.

Seasonal changes in biochemical composition of the bivalve Nucula sulcata from the Clyde Sea Area

Seasonal changes in the body weight and composition of Nucula sulcata Bronn from south of Little Cumbrae Island in the Clyde Sea Area (UK) were studied during the period August, 1969 to April, 1971. The composition of an animal of standard size was calculated for each sampling date to give information on seasonal changes independent of shell growth. Increase in body-tissue weight took place between May and October as the gonad developed and as reserves were built up. Spawning in the population took place in November, resulting in a rapid fall in body weight, and an increase in tissue water-content. These processes were less well defined in 1970 than in 1969, but the same general pattern was followed in both years. Ripe males showed a consistently higher tissue weight than females, but the female gonad contained significantly greater quantities of lipid. The changes are compared with those for other bivalves from the same general area.

An electron-microscope study of periostracum formation in some marine bivalves. I. The origin of the periostracum

Electron microscopy has revealed the presence of specialised basal cells at the base of the periostracal groove in the bivalves Mytilus edulis (L), Nucula sulcata Bronn., Cardium edule (L) and Macoma balthica (L). A common basal cell type is observed which gives rise to a pellicle in all cases except N. sulcata. The pellicle is the first part of the periostracum to be elaborated, and it is suggestd that it may be an indication of specialisation in bivalves. In N. sulcata and C. edule, an additional cell type is present. In N. sulcata, this second basal cell type appears to be directly involved in periostracum formation, whereas in C. edule an indirect role is proposed.

An electron-microscope study of periostracum formation in some marine bivalves. II. The cells lining the periostracal groove

The histology and ultrastructure of the epithelial cells of the outer and middle mantle folds of the bivalves Mytilus edulis (L), Cardium edule (L), Macoma balthica (L) and Nucula sulcata Bronn are described. The cells lining the inner face of the outer fold exhibit a prominent granular endoplasmic reticulum, and Golgi complexes which are concerned with the elaboration of granules and vesicles eventually incorporated into the periostracum. A gradual reduction in the protein synthetic apparatus occurs towards the tip of the fold. Within the cells, it is proposed that the ovoid inclusion bodies are lysosomes and that they control the rate of secretion. The cells of the middle fold are cuboidal in appearance. Those of M. edulis and N. sulcata exhibit prominent granules, whereas those of C. edule and M. balthica possess vesicles. The cells of M. edulis differ from the others in possessing stout bundles of filaments, which occupy large areas of the cell and constitute a cell web. The cells of the epithelium in all cases do not appear to be implicated in periostracum formation.

An electron-microscope investigation of the cells lining the outer surface of the mantle in some marine molluscs

The ultrastructural details of the cells lining the outer surface of the mantle in Mytilus edulis (L), Cardium edule (L), and Nucula sulcata Bronn. are described. Along the length of the outer mantle fold and the general outer surface of the mantle, the epithelial cells differ, with a progressive reduction in the protein synthetic apparatus and an increase in glycogen, while large numbers of mitochondria are evident in the apical and basal regions.

Peroxisomes in the digestive diverticula of the bivalve mollusc Nucula sulcata.

Electron microscopy of the digestive diverticula of the protobranch bivalve, Nucula sulcata, revealed the presence of peroxisomes in the basal regions of the epithelial cells lining the main and secondary ducts, and in the digestive and secretory (basophil) cells of the tubules. Those in the secretory cells are elongate and somewhat flattened, while those of the other cell types have a spherical form. Two distinct types of nucleoid are normally present within the secretory cell peroxisomes, one compact, crystalline, and finely polytubular, the other comprising isolated secondary tubules arranged in a linear series across the width of the organelle. The peroxisomes of the digestive and duct cells contain coarsely polytubular cores arranged in two clusters orientated more or less at right angles; the duct cell peroxisomes may also contain a second nucleoid in the form of a compact finely polytubular core. Sections incubated in a medium containing 3,3'-diaminobenzidine (DAB) and hydrogen peroxide reveal an electron dense reaction product within the peroxisomes of all the cell types. Catalase is considered to be responsible for the reaction.