Effects of patch size and position above the substratum during early succession of subtidal soft-bottom communities

Abstract

Early macrobenthos succession in small, disturbed patches on subtidal soft bottoms is facilitated by the arrival of post-larval colonizers, in particular by active and passive dispersers along the seaXoor or through the water column. Using a Weld experiment at two contrasting sites (protected vs. exposed to wave action), we evaluated the role of (a) active and passive dispersal through the water column and (b) the inXuence of small-scale spatial variability during succession of subtidal macrobenthic communities in northern Chile. Containers of two sizes (surface area: small-0.12 m 2 and large-0.28 m 2 ) at two positions above the natural substratum (height: low-3 cm and high-26 cm) were Wlled with defaunated sediment, installed at two sandy sublittoral sites (7-9 m water depth) and sampled after 7, 15, 30, 60 and 90 days, together with the natural bottom sediment. The experiment took place during austral fall (from late March to early July 2010), when both larval and post-larval stages are abundant. At the exposed site, early succession was driven by similar proportions of active and passive dispersers. A sequence from early, late and reference communities was also evident, but container position and size aVected the proportional abundance of dispersal types. At the protected site, the successional process started with abundant colonization of active dispersers, but toward the end of the experiment, the proportion of swimmer/crawlers increased, thus resembling the dispersal types found in the natural community. At this site, the position above the sediment aVected the proportional abundance of dispersal types, but patch size had no eVect. This study highlights that macrobenthic post-larvae can reach at least 26 cm high above the bottom (actively or passively, depending on site exposure), thus playing an important role during early succession of sublittoral soft bottoms. The active or passive use of the sediment-water interphase may also play an important role in the connectivity of benthic populations and in the recovery after large-scale disturbances of sublittoral habitats.

Testing for deterministic succession in metazoan parasite communities of marine fish

“…Species within the same family are depicted by the three successional patterns tested here (Figs 4 and 5; Appendix S1 sheet: host phylogeny). Our results emphasise the fact that parasite community succession in long-lived marine fish species follows a seriated pattern; thus, these communities can be deterministic, similar to free-living communities (Pearson & Rosenberg 1978;Rhoads & Germano 1988;Pacheco et al 2011Pacheco et al , 2012, and time (host longevity) plays a critical role in the development of such communities. Connell & Slatyer (1977) described the mechanisms that explain succession in natural communities.…”

“…Extensive successional analyses have focused on the recovery of free-living communities after a disturbance (Clarke et al 1993;James et al 2008;Pacheco et al 2010Pacheco et al , 2012. For fish parasite communities, we postulate that the beginning of succession is predictable since it would be a relatively gradual process correlated with host ontogeny and not the consequence of disturbance.…”

“…; Pacheco et al . , ). For fish parasite communities, we postulate that the beginning of succession is predictable since it would be a relatively gradual process correlated with host ontogeny and not the consequence of disturbance.…”

Succession in intertidal mussel bed assemblages on different shores: species mobility matters

“…Larvae, juveniles, and adults of mobile taxa can colonise recently disturbed habitats, leading to comparatively rapid colonisation rates and homogenisation of the landscape (Soininen 2010). In sedimentary environments, the abundance of mobile species is positively related to community stability, because mobile organisms quickly reoccupy recently disturbed habitat patches (Dittmann 1999, Pacheco et al 2012. This may explain the minor temporal increase in species richness of mobile species observed at both study sites.…”

Seasonal variability of emerging invertebrate assemblages in a sheltered soft-bottom sublittoral habitat

“…Poorly sorted fine sand with low organic matter content (b 0.5%) characterized the sediment at the 7.5-m deep study site. Further details of the study site are reported in Pacheco et al (2012bPacheco et al ( , 2013a. The sheltered location, weak bottom currents (~2.7 cm/s) and weak semi-diurnal tide (~0.3-1.3 m tidal range) allowed us to separate active emerging invertebrates from those resuspended by seabed hydrodynamics at more exposed sites (e.g., Pacheco et al, 2013a;Palmer, 1988).…”