Timing of larval release by three barnacles from the NW Iberian Peninsula

Abstract

The timing of larval release and the cues that control these rhythms (tidal, diurnal, or lunar cycles) were studied over a 2 mo period in the cirripeds Pollicipes pollicipes, Balanus spp. and Chthamalus spp., occurring on an exposed rocky shore in NW Spain. All of them showed rhythms of larval release, but the rhythms were different in each species. Chthamalus spp., which principally inhabit the upper intertidal zone, released their larvae mainly during diurnal high tides at the time of new and full moons. Larval release was greater during the afternoon than during the morning, because the amplitude of afternoon high tides was significantly higher than that of morning high tides. P. pollicipes larvae were released at morning high tide during waning moon and, to a lesser extent, during full moon. Nauplii of Balanus spp. were released during new and waning moons; almost no release occurred during full moon, and no larvae were found during the waxing moon, mainly during diurnal high tides. P. pollicipes and Balanus spp. usually began to release larvae after sunrise, which may be the factor inducing synchrony. In contrast, Chthamalus spp. released larvae at any time of day, but always coinciding with high tide, indicating that seawater may be the cue that triggers larval release in this species. Although larval release should occur during safe periods (e.g. night-time) in species such as those under study, with small unprotected colored larvae that are visible to predators, almost no larvae of any of the 3 cirripeds were found at night. Cirriped Nauplius I larvae respond positively to light, allowing larvae to travel upwards in the water column, away from congeners that could incidentally ingest their own larvae, and are transported offshore away from predators, which are more abundant close to the shore. At night this photopositive behavior does not take place, and thus the synchrony in the emission of larvae during daytime induces larval aggregation, which may increase larval survival because of the swamp effect over predators.

Stage-specific distribution of barnacle larvae in nearshore waters: potential for limited dispersal and high mortality rates

“…Wing et al 1995). However, comparatively little attention has been paid to the fate of pre-competent larval stages in shallow, inner-shelf waters soon or immediately after they are released by sessile adults (but see Macho et al 2005), although recent evidence suggests that retention and self-recruitment might be more prevalent than previously thought (Warner & Cowen 2002).…”

Larval Transport and Dispersal in the Coastal Ocean and Consequences for Population Connectivity

“…On a larger scale, a number of motile species, including snappers, herring, and blue crabs, move to particular locations for spawning (Carr et al, 2004;Heyman et al, 2005). In the temporal domain, many coral species participate in annual mass spawning events, with more than 60% of species spawning over the course of several days (Babcock et al, 1994), and crabs and barnacles tend to release their larvae at certain phases of the tide or the day (Morgan, 1995;Macho et al, 2005). While such spawning behaviors have long been thought to maximize larval survival (e.g., Hughes et al, 2000), the overall effect of localized and punctuated spawning on larval dispersal is unclear.…”

Larval ecology and synchronous reproduction of two crustacean species : Semibalanus balanoides in New England, USA and Gecarcinus quadratus in Veraguas, Panama

“…It has been suggested previously that swimming upward toward light allows the larvae to escape incidental ingestion by adults (Singarajah et al 1967, Macho et al 2005). …”

“…Studies conducted at fine temporal scales are rare (but see Macho et al 2005) because they are logistically difficult, but they can provide valuable insight into phenomena such as synchronous larval release.…”

“…Distribution and behavior during the early naupliar stages, however, has received less attention. Earlystage nauplii in the laboratory are attracted to light, presumably so that they will swim toward the surface to escape the benthic environment and its associated planktotrophic predators (Singarajah et al 1967, Macho et al 2005. Some studies (e.g.…”