Spawning behaviour and egg capsules of Concholepas concholepas (Mollusca: Gastropoda: Muricidae)

Significance of marine protected areas in central Chile as seeding grounds for the gastropod Concholepas concholepas

“…The transects were in the mid-low intertidal belt, at the Lessonia nigrescens level (Santelices et al 1980, Castilla 1981, 1988b, and were identified with plastic markers fixed to rocks with epoxy resin. Within each area, Concholepas concholepas egg capsules (Castilla & Cancino 1976) cemented (i.e. deposited by snails) to the rocks were monitored monthly.…”

“…The egg capsules were classified to stage and condition according to color, as determined in previous field and laboratory observations: (1) full white-yellowish capsules were considered to have been deposited within the preceding 20 to 30 d; (2) brownish capsules were considered to have been deposited in the preceding 30 to 40 d; (3) pink capsules were classified as containing physically stressed or infected embryos (Spight 1977); (4) empty undamaged white capsules were considered as hatched. Capsules remain cemented to the substratum for about 3 mo during the egg development (Castilla & Cancino 1976) and about 1 to 2 further months after the larvae hatch (Manríquez pers. obs.).…”

“…For egg capsules found cemented in narrow crevices, the surface area was estimated according to the closest geometrical figure measured with a caliper to the nearest 1 mm. Groups of capsules deposited by an individual female always face in the same direction and are of approximately the same length (Castilla & Cancino 1976). The length of capsules within a group was determined by measuring 1 detached capsule per group to the nearest 1 mm.…”

“…The area occupied by capsules was transformed into number of capsules and the number of capsules into number of larvae by using regressions of the relationships between (1) number of capsules per surface unit versus capsule length, and (2) number of larvae versus capsule length. The number of larvae per capsule was obtained from capsules collected from intertidal and subtidal areas and from the walls of storage tanks at the Estación Costera de Investigaciones Marinas (ECIM) at Las Cruces, by the methods described by Castilla & Cancino (1976). Analyses of covariance (ANCOVA) were used to compare the regression lines between collection sites (i.e.…”

Predator-inducible defences and local intrapopulation variability of the intertidal mussel Semimytilus algosus in central Chile

“…Regardless of the predation mode, these predators are able to breach the mussel's protective shell to reach the soft tissue in a variety of ways: (1) whole-animal ingestion, (2) invasion through the shell aperture, (3) breakage and (4) drilling. Whilst most marine gastropod predators drill holes through mussel shells using a combination of chemical and mechanical procedures (Castilla et al 1979, Serra et al 1997, crabs use their chelae and/or their mandibles to break shells (Castilla 1981, Hughes & Seed 1981, Navarrete & Castilla 1988. For each of the methods employed to consume mussels, there is an associated handling time, depending on (1) the morphological or behavioural resistance of the prey (e.g.…”