Barnacle Balanus Research Articles

Isotopic variation in the shells of recent marine invertebrates from the Canadian Pacific Coast

Shell carbonate of Balanus, Diadora, Mytilus and Calliostoma contain relatively light °13C-values which suggest that deep ocean waters, enriched with 12C of dissolved inorganic carbon (TDC), well up onto the coast of British Columbia, Canada. Another explanation for the light δ13C-values of the shells is extensive oxidation of organic carbon in the shallow surface waters along the coast, or kinetic fractionation related to growth rate of the organisms. Organisms that incorporate carbon and oxygen into shell carbonate in isotopic equilibrium with ambient seawater were used to calculate water temperatures. The calculated temperature of 7°C for Balanus suggests that these invertebrates preferentially precipitate calcite during the cooler months of the year, since the yearly temperature range of the water at Cape Beale is between 6.2° and 12.8°C The calculated temperature of 10°C for the limpet implies that this organism calcifies shell carbonate throughout the year. The bivalves Mytilus and Calliostoma with temperatures of 11° and 12°C, respectively, apparently form shells during the warmer summer months of the year. The barnacle Balanus and the limpet Diadora incorporate carbon and oxygen isotopes into shell carbonate in equilibrium with ambient seawater. This observation also applies to Mytilus and Calliostoma from Cape Beale, but not to their representatives from Lucy Island. Anomalous oxygen isotopic values are exhibited by the bivalve Clinocardium at both localities. Similarily, carbon values are anomalous for the carbonate of worm tubes (Eudistylia). These deviations of the isotopic compositions from expected values are probably related to changes in the nutrient level and/or water temperature.

Isotopic variation in the shells of recent marine invertebrates from the Canadian pacific coast

Shell carbonate of Balanus, Diadora, Mytilus and Calliostoma contain relatively light ° 13C-values which suggest that deep ocean waters, enriched with 12C of dissolved inorganic carbon (TDC), well up onto the coast of British Columbia, Canada. Another explanation for the light δ 13C-values of the shells is extensive oxidation of organic carbon in the shallow surface waters along the coast, or kinetic fractionation related to growth rate of the organisms. Organisms that incorporate carbon and oxygen into shell carbonate in isotopic equilibrium with ambient seawater were used to calculate water temperatures. The calculated temperature of 7°C for Balanus suggests that these invertebrates preferentially precipitate calcite during the cooler months of the year, since the yearly temperature range of the water at Cape Beale is between 6.2° and 12.8°C The calculated temperature of 10°C for the limpet implies that this organism calcifies shell carbonate throughout the year. The bivalves Mytilus and Calliostoma with temperatures of 11° and 12°C, respectively, apparently form shells during the warmer summer months of the year. The barnacle Balanus and the limpet Diadora incorporate carbon and oxygen isotopes into shell carbonate in equilibrium with ambient seawater. This observation also applies to Mytilus and Calliostoma from Cape Beale, but not to their representatives from Lucy Island. Anomalous oxygen isotopic values are exhibited by the bivalve Clinocardium at both localities. Similarily, carbon values are anomalous for the carbonate of worm tubes ( Eudistylia). These deviations of the isotopic compositions from expected values are probably related to changes in the nutrient level and/or water temperature.

The effect of aggregation on breeding in the barnacle Balanus glandula Darwin

The hypothesis that aggregation increases the chance of cross fertilization in barnacles is generally accepted, although it has never been tested empirically. The present study investigates the percentage of cross fertilization in experimental barnacle (Balanus glandula) populations with different degrees of aggregation. The results showed that the incidence of cross fertilization is not increased by decreasing the distance between mature adults within reach of the penis of any neighbour.

An energy budget for individual barnacles (Balanus glandula)

An annual energy budget was constructed for individual adult barnacles (Balanus glandula Darwin) for the first year after settlement. The production of body tissue, egg, shell, aquatic and aerial respiration, molting and faecal production was determined and consumption was derived from the summation of these budget items. To provide an estimation of the accuracy of the budget equation, energy budgets were constructed for three small groups of barnacles (n=40) kept under laboratory conditions, in which the budget items, including consumption, were determined independently. The results of the laboratory energy budgets indicated that consumption values derived from the summation methods for the three groups of barnacles were 7.4% higher and 16.2 and 15.6% lower than those determined by actual feeding experiments. The average consumption, assimilation and production of individual barnacles were estimated to be 699.5, 647.3 and 159.6 cal year−1, respectively. B. glandula has an exceptionally high assimilation efficiency (92.5% from the annual budget and 99.3% from the laboratory budgets) but a low gross production efficiency (22.8%) and net production efficiency (24.7%). A very large proportion of energy (67.4%) was lost in respiration. The second most important budget item was egg production (12.3%); followed in decreasing order by: shell production (6.6%)> production of body tissue (3.9%)>molting (2.3%).

Myoplasmic impedance of the barnacle muscle fiber.

Myoplasmic impedance was measured on a barnacle (Balanus nubilus) single muscle fiber that was placed in a cylindrical cavity to limit the volume and prevent the hydration of the myoplasm. At both ends of the cavity, the myoplasm was in direct contact with an electrolyte solution. When equilibrium with the external medium was reached, the myoplasmic impedance was measured at 10 degrees C with an impedance bridge at 1000 Hz. The results indicated that the myoplasmic impedance of the muscle fiber is mainly resistive. Treating the myoplasm as a suspension of small conductive particles, we deduced the specific conductivity of the contractile filaments kf and their volume fraction rho (kf = 2.78 X 10(-3) omega-1cm-1, and rho = 0.48). The experimental technique permits an estimate of the specific myoplasmic conductivity in vivo (6.27 X 10(-3) omega-1cm-1). Finally, a decrease in the pH of the external solution from 10.1 to 4.0 lowered the myoplasmic conductivity by 16%. This may be considered as indirect evidence that the conductivity of the contractile filaments is associated with the protein counter-ions, since Hinke et al. (1973. Ann. N.Y. Acad. Sci. 204, 274-296.) reported evidence that a lowering of pH decreases the number of counter-ions.

Larval Settling Behaviour of the Acorn Barnacle (Balanus pacificus Pilsbry) and its Relation to Distribution

Larval Settling Behaviour of the Acorn Barnacle (Balanus pacificus Pilsbry) and its Relation to Distribution

Hyperpolarization of a barnacle photoreceptor membrane following illumination.

Membrane potential changes following illumination of a photoreceptor cell in the lateral ocellus of a barnacle (Balanus eburneus) were studied by means of intracellular recording and polarization techniques. Illumination produces a depolarizing response. When the illumination is terminated, the membrane potential temporarily becomes more negative than the resting potential prior to illumination. Although the amplitude of this postillumination hyperpolarization depends upon the intensity as well as the duration of the light pulse, the time course is fairly constant. The hyperpolarization is not associated with any significant membrane conductance increase and is abolished by 10(-5)M ouabain. It diminishes when the external Na or K ions are removed. An intracellular injection of Na ions produces a hyperpolarization similar to that following illumination. It is suggested that the postillumination hyperpolarization is produced by an electrogenic Na pump which is activated by the Na influx during illumination.