Mulinia Research Articles

The determination of fresh organic carbon weight from formaldehyde preserved macrofaunal samples

Methodologies are presented whereby the fresh organic carbon weight of formaldehyde preserved macrofaunal samples may be estimated. Length-organic carbon weight regressions were determined for the four numerically dominant bivalves in Narragansett Bay, Rhode Island (Nucula annulata, Yoldia limatula, Mulinia lateralis, and Pandora gouldiana) and one commercially important, but less abundant species (Mercenaria mercenaria). Constants were determined to convert the dry weight of preserved softbodied organisms (polychaetes, oligochaetes, amphipods, etc.) to fresh (unpreserved) organic carbon weight. These results can be used by investigators studying the energetics of benthic communities similar to those in Narragansett Bay.

Shell-Armored Wood Cobbles as a Potential Criterion for Detrital Coal Deposits

Shell-armored wood cobbles occur on detrital-peat beaches along the seaward edge of the Mississippi Delta. Shell material consists exclusively of Mulinici lateralis, a dwarf surf clam. Soft, heavy, waterlogged wood fragments are abraded and become armored by hard shells in response to wave activity on the beach. Although their preservation potential is suspect, fossilized shell-armored wood clasts would probably be recognized as a type of coal ball and might indicate an allochthonous origin for the host coal.

Characteristics of foraging in the soft-bottom benthic starfish Luidia clathrata (echinodermata: Asteroidea): prey selectivity, switching behavior, functional responses and movement patterns.

Luidia clathrata show a strong preference for the infaunal bivalve Mulinia lateralis in Tampa Bay, Florida. Quantitative and qualitative changes in diet occurred over a 7-month period. Individuals may shift from intraoral macrofaunal feeding to intra- and extraoral detrital feeding during periods of low macrofaunal availability. In the laboratory L. clathrata showed switching behavior, feeding disproportionately on the most abundant of two simulataneously presented food models. This switching mechanism may be related to either contact-chemoreceptive rejection of lowdensity food or enhanced distance-chemoreception of high density food. The use of standardized food models eliminated the possibility that handling time was important in switching behavior. Both fed and starved individuals showed functional responses to changes in prey density. However starved individuals ingested greater numbers of prey and spent more time foraging than did fed individuals. Switching and functional response behaviors may be important in promoting nutritional uptake and in causing density-dependent mortality of prey populations. Movement patterns of L. clathrata are directional in the absence of bivalve prey, but become non-directional once patches of prey are encountered. This allows individuals to remain in areas of high prey density. Luidia clathrata has characteristics of an optimal forager, where energy is maximized per unit feeding time.

Energy resource allocation inMulinia lateralis(Say), an opportunistic bivalve from shallow water sediments

Abstract The coot clam, Mulinia lateralis, is an inhabitant of soft, salt-clay substrata and shows high rates of growth and reproduction followed by episodic mass mortality. An analysis of the effects of body size, temperature and starvation on the major components of energy balance in this bivalve suggests that it has a relatively high energy demand of approximately 10 · 66 cal · day−1 (∼ 44.66 joules · day−1) estimated for a 7 mg dry tissue mass individual at 20 °C. Since the absorption efficiency is 63%, a daily ration of 16.87 cal (∼ 70.67 joules) is required to meet the consumption requirements of this bivalve. This could be met by the filtration rate of 572 ml · day−1 in a phytoplankton cell density of 3 · 105cells · ml−1, such as occurs during bloom conditions in coastal waters or when phytoplankton is supplemented by natural seston at the sediment-water interface. The relative allocation of energy in Mulinia lateralis shows that 54.6% of the absorbed ration is channelled into growth (P g) with a rather small component of 1% becoming incorporated into shell matrix (P shell), and with 16.1% of the absorbed ration being channelled into gamete production (P r). Total production (P) thus amounts to 70.8% of the absorbed ration, with approximately 28.6% losses through respiration (R) and only 0.6% through ammonia excretion (U). The relative allocation of resources in the coot clam therefore do not differ sharply from other molluscs despite the opportunistic nature of this bivalve. Instead, Mulinia lateralis appears to be primarily adapted to exploit the high concentrations of phytoplankton and natural seston which occur at the sediment-water interface, and is likely to achieve high growth and reproductive rates provided that the available ration exceeds 17 cal · day−1. The possibility that food resources may seasonally fall below this value, and the apparent inability of Mulinia lateralis to catabolize protein during prolonged periods of starvation, may account for the episodic mass mortalities which are characteristic of this species.

Respiratory changes in the euryhaline clam, Mulinialateralis (Say), over a range of temperature and salinity combinations

The combined effects of five temperatures (15, 20, 25, 30, and 32 °C) and five salinities (10, 15, 20, 25, and 35%.) on respiratory metabolism in the euryhaline clam, Mulinia lateralis (Say), were determined from polarographic measurements of oxygen consumption. Although both the effects of temperature and salinity were statistically significant as well as their interaction effects, the effect of temperature was greater. Euryhalinity (previously ascribed to M. lateralis based only on its geographical distributions) was reflected physiologically by the few significant differences between respiration rates in various salinities at a given temperature. Significant differences were most often between rates in 20%. and the 10%. or 35%. extremes. Consistently highest rates in 20%. may reflect a salinity preferendum since this salinity was similar to long-term mean habitat salinity.

Growth and Production of the Dwarf Surf Clam Mulinia lateralis (Say 1822) in a Georgia Estuary

Growth and Production of the Dwarf Surf Clam Mulinia lateralis (Say 1822) in a Georgia Estuary

Diet and food preferences of the adult horseshoe crab Limulus polyphemus in Delaware Bay, New Jersey, USA

Adult horseshoe crabs Limulus polyphemus (L.) feed on a wide variety of infaunal and epifaunal invertebrates during their spring spawning migration in Delaware Bay, New Jersey, USA. Comparison of the gut contents with estimates of available prey showed that the most abundant potential prey item, the bivalve Gemma gemma, was avoided. The thinner shelled but comparatively scarce clam Mulinia lateralis was a preferred prey item. In the laboratory, crabs fed on G. gemma when it was the only available item but not when M. lateralis or soft-shell clams, Mya arenaria, were offered in conjunction. Large M. lateralis (>10mm) were preferred to small M. lateralis; there was no discrimination between M. lateralis and M. arenaria of the same size. Male and female horseshoe crabs had similar gut contents and laboratory feeding preferences, despite the fact that females are larger than males. Crabs spawning later in the summer contained more food than did crabs collected at the peak of spawning activity.

Factors affecting oxygen consumption in the coot clamMulinia lateralis(Say)

Abstract The effects of intrinsic (body size, gill surface area and activity patterns) and extrinsic (temperature, salinity and oxygen concentration and food) factors on oxygen consumption were measured in the mactrid clam Mulinia lateralis. Both acclimated and acute rates of VO2 were measured under 9 salinity-temperature combinations and a model is presented which indicates that: 1) body size is the over-riding factor determining VO2, 2) acclimation temperature alone has no significant effect on either fed or starved animals 3) the interaction of acclimation temperature and salinity and exposure salinity is the strongest factor influencing VO2 after body size, 4) exposure conditions are more likely to determine energy levels of expenditure than acclimation conditions. Small individuals have a greater gill surface area per body weight than larger individuals. The degree of oxygen independence is dependent on both body size and on acclimation temperature and shows a slight increase after exposure to anoxic...

The effects of anoxia and hydrogen sulphide on survival, activity and metabolic rate in the coot clam, Mulinia lateralis (Say)

The mactrid clam Mulinia lateralis (Say) shows ephemeral success in colonizing a variety of marine substrata, most commonly “soupy”, reducing muds. Depending on temperature and body size, LT50 values during exposure to anoxia and hydrogen sulphide range from 2 to 11 days, at the lower end of the range reported for infaunal bivalve molluscs. Unlike most bivalves, M. lateralis maintains high levels of feeding, shell valve, and locomotory activities under anoxia, which may be an adaptation to escape periodic burial in unstable, oxygen-deficient sediment. The rate of metabolic heat dissipation under anoxia is the same as under normoxic conditions, which implies a greatly elevated rate of anaerobic glycolysis (Pasteur effect) during anoxic exposure. This may explain the rather short anoxic survival times in this species, and emphasizes its adaptation to short-term as opposed to chronic oxygen deficiency, which may occur in dense deposit-feeding communities from which M. lateralis is excluded.

Effects of hydrodynamic and biological processes on sediment geoacoustic properties in Long Island Sound, U.S.A.

Concurrent acoustical, physical, and biological properties were measured from replicate core liner and box-core samples collected by SCUBA divers from each of two locations in Long Island Sound, 27–28 August, 1980. A very low diversity pioneer assemblage dominated by the filter-feeding bivalve Mulinia lateralis was found at the shallower (10 m water depth) FOAM site. Nearby sediments were dominated by surface-dwelling tubiculous polychaetes and amphipods. Sediment laminations produced by storm-induced erosional and depositional events were preserved at the FOAM site because sediment mixing by macrofauna was uncommon below the upper few centimeters of sediment. Horizontal patchiness of macrofauna and preservation of sediment laminations resulted in vertical and horizontal variability of sediment physical and acoustical properties. Spatial and temporal changes of dominant species at the FOAM site resulted in considerable large scale (10–100 m) variability of physical and acoustical properties of surficial sediment. A low-diversity equilibrium assemblage dominated by surface deposit-feeding bivalves and deeper-dwelling errant and tubiculous polychaetes was found at the deeper (16 m water depth) NWC site. Intense bioturbation by surface deposit-feeding bivalves precluded preservation of primary laminations created by storm-induced erosional and depositional events. Bioturbation was responsible for spatial and temporal large-scale homogeneity of physical and acoustical properties of NWC sediments. Deeper-dwelling polychaetes mixed sediment to depths of 15 cm, creating random variability of fine-scale physical and acoustical structure by production of burrows, tubes and feeding voids, and by mixing shell remains throughout the upper 15 cm. Physical and acoustical properties of many coastal marine sediments are controlled by the interaction of biological and hydrodynamic processes. Study of relationships between these two processes and resultant sedimentary properties should lead to improvement of predictive geoacoustic models for coastal environments, especially where high levels of biological activity are expected.

Temperature tolerance of embryos and larvae of five bivalve species under simulated power plant entrainment conditions: a synthesis

Thermal tolerance studies on three larval stages of five species of bivalve are compared: Crassostrea virginica, Mulinia lateralis, Argopecten irradians, Mercenaria mercenaria, and Spisula solidissima. Experiments were designed to simulate possible larval entrainment in the cooling systems of power plants and involved an 11 (temperature)x8(time-exposure) experimental matrix. Temperatures ranged from about 17.4° to 43°C at approximately 2C° intervals, and exposure times ranged from 1 min to 6 h (sometimes longer in the case of C. virginica). For all species, larval mortality generally increased with increasing exposure temperature and with increased time-exposure at any one temperature. In some species (M. mercenaria and A. irradians), a cold-shock was also apparent (i.e. increased mortality at temperatures below those at which the larvae were spawned). In the case of A. irradians, this effect was more noticeable at the trochophore stage than at the other two stages, although for all species investigated, there was a general trend of decreased thermal sensitivity with increasing age. Despite some interspecies variability from temperature to temperature and from stage to stage, S. solidissima was the most sensitive species and A. irradians was intermediate in thermal tolerance between this and the other three species. At temperatures as high as 40°–41°C, straight hinge M. mercenaria and C. virginica sustained low mortality for more than 2 h and on this basis were judged to be the most “temperature-shock” resistant of all larvae investigated. However, younger stages showed no significant differences between M. mercenaria, C. virginica or M. lateralis, and we conclude that these three species are generally very similar in their larval resistance to thermal increase. All three are more euryhaline than are the remaining two polyhaline or marine species.

The opposing effects of cadmium and nickel on calcium uptake by larvae of the clam, Mulinia lateralis

1. Effects of cadmium and nickel on the calcium uptake by larvae of the clam Mulinia lateralis was studied using the 45Ca isotope tracer method. 2. Calcium uptake by larvae of M. lateralis was depressed by nickel but stimulated by cadmium. 3. A model was proposed to explain the opposing effects of cadmium and nickel on calcium uptake.

Refuges for infaunal bivalves from blue crab, Callinectes sapidus (Rathbun), predation in Chesapeake Bay

Monthly field sampling in the Choptank River, Chesapeake Bay, revealed rapid increases in population densities of infaunal bivalves in winter and spring followed by a decline in summer, presumably as a result of increased predation. Spat settlement of Mya arenaria L. occurred predominately in late fall and winter, declining in early spring. Macoma balthica (L.) spat settled primarily in spring. Spat of Macoma mitchelli Dall and Mulinia lateralis (Say) were found throughout most of the year. Field studies revealed a tendency for larger Mya arenaria, Macoma balthica, and M. mitchelli to be found deeper in the sediment. Laboratory studies tested the effectiveness of possible refuges within the sediment in protecting the soft clam, Mya arenaria, from blue crab ( Callinectes sapidus Rathbun) predation. Mya arenaria living below 10 cm were foraged for by blue crabs less effectively than those living closer to the surface. In the field, soft clams which settled in the fall were found living below 10 cm by the following May, reaching their maximum burial depth of 25 cm in June–July. An artificial plant structure also afforded some degree of protection from blue crabs in laboratory experiments: sparse and dense assemblages of artificial plants allowed higher survival of M. arenaria compared with control treatments. The protection afforded infaunal bivalves by these spatial or structural refuges is not absolute, although living deep within the sediment or within vegetation beds reduces the risk of predation in comparison to living near the sediment surface or in unvegetated areas.

The effects of mercury, copper, and zinc on calcium uptake by larvae of the clam, mulinia lateralis

A sensitive and rapid bioassay system using Ca-45 uptake by larvae of Mulinia lateralis as indicator is described. The values of Ca uptake per larva−1 versus elapsed time were linear and some of the Ca uptake rates, expressed as pg Ca larva−1 h−1, were 148.2 (no added heavy metal), 114.4 (20 µg kg−1 of added Hg), 89.7 (200 gg kg−1 of added Zn) and 20.5 (40 µg kg−1 of added Cu). Linearities were also obtained by plotting log of Ca uptake per larva−1 against heavy metal concentrations. A new terminology, xCa inf50 supt , was proposed which expressed the concentration of heavy metal, x, causing 50% depression of Ca uptake over the exposure time, t. For Cu, Hg, and Zn, the values of x Ca inf50 sup72h were 18.5, 26.5 and 176.0 µg kg−1 respectively, which were comparable to the published values of LC50. The effectiveness of Ca uptake depression on a weight basis was Cu > Hg > Zn, and the same sequence was also observed for larval mortalities.

The calcium uptake by larvae of the oyster, Crassostrea virginica, and the clam, Mulinia lateralis

1. 1. The uptake of calcium by larvae of the oyster ( Crassostrea virginica) and the clam ( Mulinia lateralis) was measured using the 45Ca isotope tracer method. 2. 2. An equation was established for the calculation of true calcium uptake and the rates expressed as ng Ca/larva/hr were 0.39 and 0.34 ± 0.16 ( n = 4) for 3- and 11-day-old oyster larvae, and 0.03 and 0.15 for 7- and 9-day-old clam larvae, respectively. 3. 3. This system is sensitive, rapid, simple and potentially useful for the measurements of calcium metabolism, shell formation, aquaculture and toxicity.

Predation on Estuarine Infauna: Response Patterns of Component Species

The effect of predation by blue crabs and fishes on all species of infaunal macrobenthos of a subtidal sandy bottom in the York River, Virginia, was investigated by manipulative field experiments. Wire mesh cages were used both to exclude all large predators from and to confine different predators to small areas of the natural bottom. After 2 months, many species showed significant differences between the various treatments. There were similar patterns of species responses in three separate years. Species tended to fit one of two categories. Those species which had tough tubes, which lived deep in the sediment, or which could quickly retract deep into the sediment were shown experimentally not to change much in abundance regardless of whether predators were excluded or included. These species were generally the numerical dominants in the natural community—e.g.Peloscolex gabriellae, Heteromastus filiformis, Spiochaetopterus oculatus, andPhoronis psammophila. Other species which lived near the surface or exposed on the surface responded to experimentally altered predation intensity with large changes in density. These species were either uncommon or only sporadically abundant in the natural community—e.g.Polydora ligni, Streblospio benedicti, Mulinia lateralis, andLyonsia hyalina. This evidence indicates that the abundant species in the natural community are abundant because they avoid predators.

Temporal Variation in Upper Bay Mesohaline Benthic Communities: I. The 9-m Mud Habitat

Yearly and seasonal changes in the structure of the macrobenthic (>1.0 mm) community occurring in the 9-m mud habitat of the Calvert Cliffs region of the Chesapeake Bay were examined for three years. Seasonal changes in the numerically dominant species resulted in varying community structure and was characterized by a near total faunal depletion during summer, initial recolonization during early fall, secondary recolonization during late fall, and growth and structural development during winter and spring. The faunal depletion that occurred each summer caused the cycle to repeat on an annual basis. The structure of the community was similar each year during initial recolonization (fall), but varied during secondary recolonization (winter and spring), reflecting the recruitment success of species that reproduce in the fall (i.e.,Macoma balthica, Mulinia lateralis, Nereis succinea, andParaprionospio pinnata). These findings have profound implications for the design and interpretation of power plant preoperational-postoperational impact studies.

Effects of environmental factors on radiocadmium uptake by four species of marine bivalves

Temperature, salinity, bottom-sediment type, and zinc concentration all influenced Cd uptake by 4 marine bivalves (Mya arenaria, Mytilus edulis, Mulinia lateralis and Nucula proxima) in short-term static assay systems using 109Cd as a tracer. The experimental system consisted of aquaria containing 20 l of seawater maintained under controlled light and temperature conditions. The water contained either 5 or 20 μg/l Cd and tracer. Distribution and kinetics of the metal were monitored in the water column and organisms. The results demonstrate that Cd uptake rates differed widely among the organisms tested. An increase in temperature increased Cd uptake rate by all test organisms. A decrease in salinity increased Cd uptake by all organisms tested. The presence of bottom sediment depresses Cd accumulation in some benthic animals. Zinc in concentrations of 0.5 mg/l substantially decreased Cd uptake by Mytilus edulis and Mulinia lateralis. It is suggested that all important species and environmental variables be considered when studying heavy-metal uptake by marine organisms or when establishing water-quality criteria.

The ribosomal RNA cistrons in clam gametes

The localization, amplification, and multiplicity of the rRNA cistrons in gametes of the coot clam, Mulinia lateralis, have been investigated using isopycnic centrifugation and DNA-RNA hybridization. The rRNA cistrons appear to be localized in a high-density satellite which makes up 3–5% of the DNA in both gametes. Oocyte DNA binds, on the average, 1.6 times as much rRNA as does sperm DNA. The mitochondrial DNA component of oocytes accounts for 19% of the total DNA, as estimated by denaturation and reannealing followed by isopycnic centrifugation. Hence, the ribosomal cistrons are amplified about twofold ( 1.6 0.81 ) in these oocytes. The haploid Mulinia genome contains approximately 120 cistrons for rRNA, as measured by hybridization with Xenopus rRNA at saturating concentration. The Mulinia oocyte therefore contains many fewer copies of rDNA than does the oocyte of Spisula, a closely related species, in which the ribosomal cistrons exist in greater multiplicity (195 cistrons; Collier, J. R. (1971), Exp. Cell Res. 69, 181–184), and are amplified at least fivefold (Brown, D. D., and Dawid, I. B. (1968), Science 160, 272–280). Since the oocytes of these two clams are the same size and begin rRNA synthesis at the same time after fertilization, the magnitude of rDNA amplification must not be strictly related to the needs of the developing embryo.

Some factors affecting the colonization of a dredged channel

Standing crop, population size, and species diversity of the macrobenthic organisms in an estuarine channel were studied before and after dredging. A new suction-corer which sampled an area 0.1 m2 to a depth of 30 cm was used in order to insure the inclusion of large, deep-dwelling animals. Eleven months after dredging, biomass and number of species and specimens had not recovered to pre-dredging levels. Colonization began with relatively large, swiftly moving forms such as the errant polychaete Nereis succinea and the crab Neopanope texana sayi. Stations in silt and mud regions recovered more slowly than those in sandier sediments. Most of the dominant and subdominant species had not recovered 11 months after dredging, and the previously abundant polychaetes Notomastus latericeus and Clymenella torquata had virtually disappeared. Only relatively uncommon lamellibranchs such as Tellina agilis, Lyonsia hyalina and Mulinia lateralis increased after dredging. Distribution of sediment types changed as the result of modified tidal velocities in the channel. Mud and silt were removed by the dredge, exposing the sand underneath, and sandy stations became muddier as the result of lowered current velocities. Marked changes in species composition reflected this change in sediment character. Eleven months after dredging no evidence of succession was found, but colonization had begun. Values of all three parameters studied were reduced to small fractions of pre-dredging levels, although species diversity in sandy sediments exceeded pre-dredging levels.