Bearded Horse Mussel Research Articles

Macrozoobenthos in the intertidal zone of the Ly Son island

The surveys of macrozoobenthos fauna of Ly Son tidal area were carried out at 8 stations in September 2016. The 4 replicate samples were collected in high, middle and low tidal zones at each station. The results record 92 taxa of mollusc (accounting for 35% of total number of taxa), 76 taxa of crustacean (29%), 71 taxa of polychaete (27%) and 22 taxa of echinoderm (9%). Among them, there are 7 species of valuable resources that were exploited for food such as sea cucumber (Holothuria (Semperothuria) cinerascens), collector urchin (Tripneustes gratilla), diadema urchin (Echinothrix diadema), Diadema savignyi (belonging to Echinoderma), strawberry conch (Strombus luhuanus), goldmouth turban (Turbo chrysostomus) and bearded horse mussel (Modiolus barbatus). Some species with beautiful shapes and colors are used for handycraft such as black-lip pearl oyster (Pinctada margaritifera), small giant clam (Tridacna maxima), Chinese cowrie (Cypraea chinensis)... The densities of mactozoobenthos vary from 38 to 1,632 individuals/m2 between stations and tend to increase from high to low tide zones; from sandy bottom and shore rock to dead coral habitats covered by seaweed and seagrass bed.

Influence of Salinity on Physiological Response of the Bearded Horse Mussel Modiolus barbatus and Noah’s Ark Shell Arca noae

Abstract Bearded horse mussel Modiolus barbatus and Noah’s ark shell Arca noae are a species of interest for the diversifying shellfish aquaculture on the south-eastern coast of the Adriatic. In this study, oxygen consumption (OC), total ammonia excretion (TAM) and clearance rate (CR) responses to the changes in seawater salinity (37, 30, 25 and 20) were investigated in the laboratory. There is a statistically significant influence of salinity on oxygen consumption and TAM excretion of Noah’s ark shell, while the time of exposure to different salinities is significantly correlated to TAM excretion by the bearded horse mussel. Mean OC of Noah’s ark shell ranged from 0.14 ± 0.06 to 0.54 ± 0.27 mg O2g−1h−1 and that of bearded horse mussel from 0.18 ± 0.17 to 0.26 ± 0.14 mg O2g−1h−1. Mean values of TAM excretion of Noah’s ark shell ranged from 2.14 ± 1.52 to 7.22 ± 6.04 μmol g−1 h−1 and for bearded horse mussel from 0.98 ± 0.53 to 2.78 ± 2.96 μmol g−1 h−1. Salinity and exposure time have a significant influence on the CR of Noah’s ark shell, whilst salinity has been found to be the determining factor for the bearded horse mussels’ CR. Mean values of Noah’s ark shell CR ranged from 0.96 ± 0.54 to 4.18 ± 1.15 l h−1g−1 and for bearded horse mussel from 2.43 ± 0.99 to 4.23 ± 0.84 l h−1g−1. Higher oxygen consumption to total ammonia excretion (O:N) ratios at lower salinities indicated the use of proteins as a metabolic substrate for both species. Noah’s ark shell has greater energy expenditure related to respiration and TAM excretion than the bearded horse mussel.

THE EFFECT OF FOOD QUANTITY ON PHYSIOLOGICAL RESPONSES OF THE BEARDED HORSE MUSSEL MODIOLUS BARBATUS AND THE NOAH’S ARK SHELL ARCA NOAE

The aim of the work was to investigate oxygen consumption, ammonia excretion, O:N ratio derived from oxygen consumption and ammonia excretion, and the clearance rate of the bearded horse mussel Modiolusbarbatus(Linnaeus, 1758) and the Noah's Ark shell ArcanoaeLinnaeus, 1758with regard to different food availability (100%, 50% and starving) during a fifteen day experiment. In this study, food quantity significantly affected ammonia excretion and O:N ratio for both species. Time spent under feeding regime resulted to increasing oxygen consumption and clearance rate values of the bearded horse mussel and the ammonia excretion values and O:N ratios of both species. Clearance rate and ammonia excretion followed a similar increasing trend over time. The consequence of increasing ammonia excretion over time was the concomitant reduction of the O:Nratio.Both species showed high values of clearance rate, an important information when choosing the farming site. Metabolic cost of respiration for starving animals was higher for M. barbatus than for A. noae, which suggests that A. noae would be a better choice for farming in oligotrophic environments.

The Size Driven Variations in Physiological Responses of the Bearded Horse Mussel Modiolus barbatus and the Noah’s Ark Shell Arca noae

Bearded horse mussel and Noah’s ark shell are sometimes observed to live together in groups. Oxygen consumption, ammonia excretion and clearance rate were investigated on these species under laboratory conditions considering different size of individuals divided into three size groups (less than 25 mm; 25 to 50 mm and larger than 50 mm). Body size of both species significantly influenced oxygen consumption, ammonia excretion and clearance rate of the Noah’s ark shell. In both species, respiration and clearance rate decreased with body size while excretion rate increased with body size. For Noah’s ark shell groups of 25 to 50 mm and smaller than 25 mm, the atomic ratio between oxygen consumption and ammonium excretion i.e. O:N ratio was detected to be greater than 30. The same applies to a group of the bearded horse mussels smaller than 25 mm. Animals of both species larger than 50 mm have O:N ratio smaller than 30 indicating use of proteins as metabolic substrate, compared to use of lipids and carbohydrates in younger animals.

First record of bearded horse mussel, Modiolus barbatus (Bivalvia: Mytiloida: Mytilidae) from the south-western coast of India

The new occurrence of a mytilid,Modiolus barbatusis recorded for the first time in Kerala based on a single specimen associated with the seaweed,Ulva lactucain the intertidal zones of the Vizhinjam coast. The distributional range of this species is extended from the south-eastern coast to the south-western coast of India. Currently, seven species of the genusModiolus, includingModiolus barbatus, are recognized from the Indian coast.

Incidence of damaging endolith infestation of the edible mytilid bivalve Modiolus barbatus

Endolith microboring infestation in bearded horse mussel Modiolus barbatus collected from Mali Ston Bay, Croatia during 2010 was studied for incidence and distribution of damage in bivalve shells and in relation to shell length and condition index. Macroscopic changes in colour and thickness of the inner shell surface were investigated in order to determine endolith presence and host response. Results showed a significant percentage of over 93% of shells to be infested by endoliths. Analyses of shells grouped by the degree of infestation showed that the majority of specimens were moderately infested, most commonly within the central area of the shell. Microboring endoliths were dominated by cyanobacteria Plectonema (Leptolyngbya) terebrans, Mastigocoleus testarum, Hyella caespitosa and by the green algae Phaeophila sp. and Ostreobium quekettii. In addition, characteristic scars were carved into the host shell by the boring bivalve Rocellaria dubia in over 40% of sampled shells. SEM photographs revealed added shell layer deposition in infested specimens; in some cases, a prismatic layer is formed on the inner shell surface. This study shows that the incidence of infestation increases with shell length and that the degree of endolith infestation has adverse effects on the condition index.

The potential for aquaculture of the bearded horse mussel (Modiolus barbatus) and Noah’s Ark shell (Arca noae) in southern Croatia

To assess the potential of the bearded horse mussel (Modiolus barbatus) and Noah’s Ark shell (Arca noae) for aquaculture in southern Croatia, we analyzed their survival and growth rates under two experimental conditions—suspended culture and on-bottom culture. Furthermore, we investigated feeding on zooplankton by these two species in suspended culture conditions and compared them with previously published results of their feeding on zooplankton in the natural benthic environment. Experimental studies were conducted in Mali Ston Bay (Adriatic Sea) from December 2009 to December 2010. Differences were observed in terms of survival of tagged M. barbatus and A. noae—specimens of M. barbatus exhibited much better survival rates both in suspended culture and in on-bottom cages than did A. noae. Growth of A. noae under both culture conditions was essentially negligible, while M. barbatus grew several times faster in suspended culture than on the bottom. Values for the growth constant K and L inf for M. barbatus in suspended culture were 0.45 year−1 and 55.9 mm, while corresponding values for on-bottom culture were 0.09 year−1 and 58.6 mm, respectively. Zooplankters were present in the stomachs of 86.3 % of M. barbatus and 86.4 % of A. noae. Most abundant taxa were bivalve larvae followed by tintinnids, copepods, unidentified eggs and gastropod larvae. In conclusion, this study clearly shows that M. barbatus is a promising candidate for suspended aquaculture in southern Croatia.

Field studies and projections of climate change effects on the bearded horse mussel Modiolus barbatus in the Gulf of Thermaikos, Greece

Field studies and projections of climate change effects on the bearded horse mussel Modiolus barbatus in the Gulf of Thermaikos, Greece

Seasonal fatty acid profile analysis to trace origin of food sources of four commercially important bivalves

Knowledge of bivalve food sources has great importance in aquaculture areas where cultured species usually occur at higher densities than in natural populations. Except phytoplankton, which is considered as their primary food sources, bivalves can use other food sources such as detritus, bacteria and zooplankton. The objective of this study was to determine food sources of four commercially important bivalve species co-existing in the Mali Ston Bay — most important aquaculture area of the eastern Adriatic Sea. Food sources were investigated by analyzing the fatty acid profiles of digestive gland and muscle tissues of the European flat oyster Ostrea edulis and the black mussel Mytilus galloprovincialis, cultured in the water column, and the bearded horse mussel Modiolus barbatus and Noah's ark shell Arca noae from natural populations. Digestive gland fatty acid analysis revealed that during the period of higher plankton abundance in spring and summer, all species ingested mainly phytoplankton followed by zooplankton and detritus. During the low plankton abundance of the autumn–winter period zooplankton and/or detritus became more important in a bivalve diet. Fatty acid composition of muscles indicated differences in selective incorporation of polyunsaturated fatty acid (PUFA) from their diets. While A. noae and M. barbatus accumulated significantly PUFAs during all and O. edulis during spring–summer period, in M. galloprovincialis this tendency was not observed at all. This suggested better utilization of ingested food in bottom-dwelling species. Because all four species consumed similar food sources they were in competition. However, as investigated species in Mali Ston Bay exist in high density, primary production plus the availability of other food sources in this area was probably sufficient to satisfy demands for all species. Aquaculture in the study area depends wholly on natural spat. This suggests that larviphagy, observed for all species, might constitute a self-regulating restriction to natural populations and/or commercial aquaculture growth.

Field studies on the relation between the accumulation of heavy metals and metabolic and HSR in the bearded horse mussel Modiolus barbatus

The present study aims to examine whether the seasonal changes in the levels of heavy metals Cd and Pb in the gills of sublittoral mussel Modiolus barbatus from populations distributed in Thermaikos Gulf are correlated to seasonal molecular (Heat Shock Response) and metabolic stress responses of this species. Our results indicate a season effect in the accumulation of heavy metals in the gills of bivalves in the area of Thermaikos Gulf, possibly implicating biological (reproductive cycle), natural (rivers' flow) and anthropogenic factors. Among the members of heat shock proteins (Hsps) examined, inducible Hsp70 seemed to play a major cytoprotective role against toxicity of metals. However, bivalves' tolerance against heavy metals may decrease during warming, arising further questions for their survival in context of global warming.

Growth and survival rates of bearded horse mussel (Modiolus barbatus Linne, 1758) in Mersin Bay (Turkey)

The growth and survival rates of four size classes (10, 15, 20, and 25 mm) of bearded horse mussels (Modiolus barbatus) grown in net bags in Mersin Bay, Izmir, were assessed from May 2001 to May 2002. Temperature ranged 14-23°C, average chlorophyll a was 3.34±0.35 μg/l, average total particulate matter 12.43±0.68 mg/l, and average particulate organic carbon 210.23±18.00 μg/l. Shell lengths increased 23.05, 19.76, 19.40, and 12.09 mm in the four class- es (from small to large) and live weights increased 13.21, 10.46, 10.06, and 4.96 g, respective- ly. Survival rates ranged from 25% in the smallest size class to 87.5% in the 20 mm class (p<0.05). Mussels grew significantly fastest in the smallest size class (p<0.05).

HISTOPATHOLOGY OF MODIOLUS BARBATUS

Infection of Gymnophallus sp. in the bearded horse mussel (Modiolus barbatus) was studied in samples collected during 1 year in the Mali Ston Bay (eastern Adriatic Sea). Mean prevalence of sporocyst was low (3.5%), which peaked in February (7.1%), whereas the mean metacercariae prevalence was 8.1%, peaking in September (16.7%). Histologically the Gymnophallus sp. sporocyst infection in bearded horse mussel resulted in clear reaction of bivalve tissue, where the induced changes depend strongly on the site of trematode infection. Retardation of gametogenesis, necrosis of connective tissue and hemocytic infiltration are the main histological features of infection in this new host.