The physiological ecology of Mytilus californianus Conrad

Abstract

The rates of oxygen consumption, filtration and ammonia excretion by Mytilus californianus have been related to body size and to ration. The rate of oxygen consumption (VO) by individuals while immersed, measured on the shore, resembled rates recorded for mussels starved in the laboratory. VO by M. californianus was relatively independent of change in temperature, with a Q (13-22° C) of 1.20. In contrast, the frequency of heart beat was more completely temperature dependent [Q (13-22° C)=2.10]. Filtration rate showed intermediate dependence on temperature change [Q (13-22° C)=1.49] up to 22° C, but declined at 26° C. Both VO and filtration rate declined during starvation. The utilisation efficiency for oxygen was low (approx. 4%) between 13 and 22° C, but increased to 10% at 26° C. Three components of the "routine" rate of oxygen consumption are recognised and estimated; viz. a basal rate (0.136 ml O h for a mussel of 1 g dry flesh weight), a "physiological cost" of feeding (which represented about 6% of the calories in the ingested ration), and a "mechanical cost" of feeding which was three times higher than the physiological cost. The ratio oxygen consumed to ammonia-nitrogen excreted was low, and it declined during starvation. These data are compared with previously published measurements on Mytilus edulis, and the two species of mussel are shown to be similar in some of their physiological characteristics, though possibly differing in their capacities to compensate for change in temperature. For M. californianus, the scope for growth was highest at 17-22° C and declined at 26° C; it is suggested that exposure to temperatures in excess of 22° C, as for example during low tides in the summer, might result in a cumulative stress on these populations of mussels by imposing a metabolic deficit which must be recovered at each subsequent high tide. The high "mechanical cost" of feeding imposes a more general constraint on the scope for activity of the species.

Micro-scale environmental variation amplifies physiological variation among individual mussels

“…Gills are the principal site of gas exchange and, thus, are likely poised to cope with fluctuating environmental oxygen concentrations and/or with variation in ROS production driven by changes in body temperature. Mantle tissue may assume some of this gasexchange function when the animal is emersed [59]; mantle had the highest levels of antioxidant capacity against peroxyl radicals. Muscle, on the other hand, is generally considered to function largely via anaerobic pathways [59].…”

“…Mantle tissue may assume some of this gasexchange function when the animal is emersed [59]; mantle had the highest levels of antioxidant capacity against peroxyl radicals. Muscle, on the other hand, is generally considered to function largely via anaerobic pathways [59]. While muscle rspb.royalsocietypublishing.org Proc.…”

Ammonia-nitrogen production by the bivalve molluscTapes japonica and its recovery by the red seaweedHypnea musciformis in a tropical mariculture system

“…2) it follows that the ammonia-N production was inversely related to the quantity of food consumed, as shown in Figure 3. Little data exists on the influence of nutritional levels on the rate of ammonia excretion for bivalve molluscs, except for starved animals (Bayne, 1973(Bayne, , 1976Bayne et al, 1976). However, the effects of nutrition have been more thoroughly investigated for zooplankton where it has usually been found that nitrogen excretion increases with an increased ration (Corner et al, 1965;Butler et al, 1970;Takahashi & Ikeda, 1975).…”

“…One other possibility has to be considered before we may conclude that nutritional levels are or are not inversely related to ammonia-N excretion for T. japonica. Bivalves will normally satisfy their metabolic energy requirements by using carbohydrates, then lipids and then protein (Gabbott & Bayne, 1973;Bayne, 1976). So, it is possible that at the lower food levels the protein in the phytoplankton would be utilized for the metabolic requirements and that the resulting deamination of the protein would increase the rate of ammonia excretion at the lower food levels.…”

Ammonium cycling in the rocky intertidal: Remineralization, removal, and retention

“…When we independently estimated the contribution of mussel excretion, the estimates were concordant with our tidepool tracer dilution calculations. We used an empirically derived relationship between NH z 4 production and mussel dry mass (dry mass, g); NH z 4 production (mg h 21 ) 5 23.88 dry mass 0.817 (Bayne et al 1976a) derived from Northern Puget Sound where summer water temperatures and salinities are similar to those in the Strait of Juan de Fuca. Using our prior measurements of shell length and abundance in each experimental tidepool and the relationship between mussel dry mass and shell length (J. T. Wootton pers.…”