The early life history traits of the labrisomid blenny Auchenionchus crinitus (Jenyns, 1842) from subtidal rocky reefs were studied, based on microstructure analysis of sagittae of their pelagic larvae (4.01 mm NL −12.50 mm SL). Ichthyoplankton was collected in shallow (<20 m) nearshore waters off Isla Santa María, Antofagasta, northern Chile every 15 days during austral autumn–winter 2014 (five sampling days). During late May and early June, larval abundance was low (median ± MAD, 39.06 ± 5.08 ind. 100 m−3), increasing significantly during mid-June to early August (110.98 ± 47.66 ind. 100 m−3). Using 354 sagittae, the back-calculated hatch dates indicated the occurrence of three hatching events, two in autumn and one in winter. Hatching occurred mainly during the illuminated phases of the lunar cycle. All three batches had similar estimated larval sizes at hatch (3.2–3.7 mm SL), as well as similar growth rates (0.19–0.22 mm day−1) during the first 30 days of life. During the study period, shallow waters were well mixed, with seawater temperature of 14.73 ± 0.58°C and salinity of 34.84 ± 0.04. This is the first estimation of early life history traits of this cryptobenthic species from rocky reefs of Chile.

Early life traits (ELT) of the sand-burrowing cryptic marine fish Sindoscopus australis (family Dactyloscopidae) were compared between cohorts hatched during winter and spring 2013, in nearshore rocky reefs off central Chile. Pelagic larvae were similarly abundant during both periods, but larger larvae were collected during austral spring. The sagittal otolith microstructure and size analyses also indicated that size-at-hatch was larger (4.7 mm) for the winter cohort, but winter larvae experienced slower growth rates (0.145 mm day−1 ± 0.008). Conversely, larvae from the spring cohort hatched at smaller sizes (2.9 mm), but they grew faster (0.182 mm day−1 ± 0.008). Hatching periods were coupled with the lunar cycle; in winter, hatching events were related to neap tides (first and third quarter moon), increasing chances of self-recruitment. Meanwhile, during spring, hatching occurred during spring tides, particularly over the new moon, decreasing chances of larval mortality by predation. Otolith traits used to test asymmetry among cohorts showed inconsistent results. Only sagittal perimeter presented fluctuating asymmetry, showing higher variance for the winter cohort. We conclude that this burrowing species displays different reproductive tactics at a seasonal scale.

Beach ecosystems extend from dune to offshore areas along most coasts, and provide essential services that are not provided by any other ecosystem. Indeed, sandy systems contain unique biodiversity and supply nursery and foraging areas for numerous commercially important marine species, such as flatfish. However, these systems are threatened by increasing anthropogenic pressure. Green tides (GT, i.e. accumulations of green opportunistic macroalgae) are a major human-induced threat to marine ecosystems, from inshore to nearshore. This eutrophication process greatly affects both benthic invertebrate communities and flatfish communities, within sheltered and non- or microtidal systems. However, the responses of dynamic open macrotidal sandy systems to eutrophication in the form of macroalgal mats are not yet fully understood. In particular, understanding the effects of GT on two connected biological compartments (infauna and flatfish) within two connected habitats (intertidal and subtidal) is crucial. Here, we set out to assess the influence of several environmental variables, including Ulva biomass, on the variability in infauna and flatfish communities in both the intertidal and the subtidal at four sites impacted or not by GT. In total, 110 biodiversity samples were analysed with classic and novel analytical approaches. Our results demonstrate that the presence of GT specifically impacts intertidal macroinvertebrate communities. However, small effects of GT on subtidal infauna communities, as well as on species-specific flatfish at both intertidal and subtidal, were still detectable. Our findings underline the vulnerability of highly dynamic ecosystems exposed to anthropogenic stress, in particular intertidal sandy shores.

Les instruments de mesures des courants en mer permettent d'obtenir un nombre d'informations de plus en plus important grâce à des techniques de mesures de plus en plus sophistiquées. En particulier, les mesures ponctuelles de vitesses et de pression permettent d'obtenir des informations sur l'énergie de la houle et sa direction de propagation. Nous avons montré dans ce travail que le caractère partiellement stationnaire des houles réelles peut être mesuré de façon quantitative à partir de données synchrones de vitesse et/ou de pression. Ces capacités sont illustrées par des exemples de mesures à partir de différents appareils immergés en zone littorale (S4, ADV, ligne de capteurs de pression).