Quantification of larval traits driving connectivity: the case of Corallium rubrum (L. 1758)

Abstract

larvae to quantify their free fall speeds, swimming activity frequency and swimming speeds. The experiment was repeated under different light conditions and at different larval ages. PLD ranged from 16 days (95 % survival) to 42 days (5 % survival). Larvae exhibited negative buoyancy with a free fall speed decreasing linearly with age, at a velocity varying from −0.09 ± 0.026 cm s −1 on day 1 to −0.05 ± 0.026 cm s −1 on day 10. No significant difference was found either in the activity frequency or in the mean swim velocities during active periods for age (up to 12 days old) or under different light conditions. C. rubrum larvae maintained active swimming behavior for 82 % of the time. This activity frequency was combined with age-varying free fall periods in the motility behavior model extrapolated up to 15 days old, resulting in a mean upward speed that increased from 0.045 cm s −1 (day 1) to 0.056 cm s −1 (day 15). This larval motility behavior, combined with the extended PLD, confers on C. rubrum larvae an unsuspectedly high dispersive potential in open waters.

Contrasted levels of genetic diversity in a benthic Mediterranean octocoral: Consequences of different demographic histories?

“…Such local genetic structure has been demonstrated for other octocorals in this area, with maximum F ST reaching 0.2 for C. rubrum and 0.1 for P. clavata (Mokhtar-Jamaï et al, 2011). This has been linked to reduced dispersal abilities of the larval stage in Mediterranean octocorals (Martínez-Quintana et al, 2015). In E. verrucosa, the lecithotrophic larvae are supposed to have a short, but unknown life span (Sartoretto & Francour, 2011).…”

Does historical harvesting affect colony size distribution and genetic diversity in Corallium rubrum (Linnaeus, 1758)? Evidences from the Southern Mediterranean commercial banks

“…High genetic differentiation found between shallow water colonies at less than 1 m distance (Costantini et al, 2007a, b;Ledoux et al, 2010a, b) suggests a short effective dispersal of the larvae. Conversely, larval observation in aquaria (Martínez-Quintana et al, 2015) and mathematical models (Guizien & Bramanti, 2014) theorize that connectivity between distant populations may occur.…”

A comparison of genetic connectivity in two deep sea corals to examine whether seamounts are isolated islands or stepping stones for dispersal

“…These include hydrodynamic features such as oceanic fronts, upwellings, and the stratification of water masses, all of which can constrain the dispersal of long-lived larvae12131415. In contrast, rafting can result in long-range dispersal for species that have direct-developing larvae with no dispersal phase16 and larval behaviours can facilitate dispersal in currents1718. Even anthropogenic factors such as pollution and coastal runoff can affect dispersal and population genetic structure19 and isolation-by-distance, although intuitively satisfying as a model for larval dispersal, is only rarely found in marine populations with planktonic larvae e.g.…”