2004. Carbon cycling through the pelagic foodweb in the northern Humboldt Current off Chile (23(S). e ICES Journal of Marine Science, 61: 572e584.The structure of the zooplankton foodweb and their dominant carbon fluxes were studied in the upwelling system off northern Chile (Mejillones Bay; 23(S) between October 2000 and December 2002. High primary production (PP) rates (1e8 gC m ÿ2 d ÿ1 ) were mostly due to the net-phytoplankton size fraction (O23 mm). High PP has been traditionally associated with the wind-driven upwelling fertilizing effect of equatorial subsurface waters, which favour development of a short food chain dominated by a few small clupeiform fish species. The objective of the present work was to study the trophic carbon flow through the first step of this ''classical chain'' (from phytoplankton to primary consumers such as copepods and euphausiids) and the carbon flow towards the gelatinous web composed of both filterfeeding and carnivorous zooplankton. To accomplish this objective, feeding experiments with copepods, appendicularians, ctenophores, and chaetognaths were conducted using naturally occurring plankton prey assemblages. Throughout the study, the total carbon ingestion rates showed that the dominant appendicularian species and small copepods consumed an average of 7 and 5 mgC ind ÿ1 d ÿ1 , respectively. In addition, copepods ingested particles mainly in the size range of nano-and microplankton, whereas appendicularians ingested in the range of pico-and nanoplankton. Small copepods and appendicularians removed a small fraction of total daily PP (range 6e11%). However, when the pico-C nanoplankton fractions were the major contributors to total PP (oligotrophic conditions), grazing by small copepods increased markedly to 86% of total PP. Under these more oligotrophic conditions, the euphausiids grazing increased as well, but only reached values lower than 5% of total PP. During this study, chaetognaths and ctenophores ingested an average of 1 and 14 copepods ind ÿ1 d ÿ1 , respectively. In terms of biomass consumed, the potential impact of carnivorous gelatinous zooplankton on the small-size copepod community ( preferred prey) was important (2e12% of biomass removed daily). However, their impact produced more significant results on copepod abundance (up to 33%), which suggests that carnivorous gelatinous zooplankton may even modulate (control) the abundance of some species as well as the size structure of the copepod community.

Questions Fire is a key factor influencing Araucaria araucana forests, but the impact of fire severity on the understorey vegetation is not well understood. In this study we seek to answer the following questions: (a) how do initial plant diversity, composition and spatial distribution of the understorey vegetation change in response to different levels of fire severity; and (b) does the abundance of dominant tree species exhibit different patterns across a fire severity gradient shortly after fire? Location Old‐growth Araucaria araucana–Nothofagus pumilio forests in the Andes of south‐central Chile (38° S, 71° W) burned in 2015. Methods We evaluated the post‐fire plant regeneration across a fire severity gradient ranging from unburned forests to areas of high fire severity. One year after fire (in February 2016), we measured woody and herbaceous species richness, abundance, height, origin (native vs exotic species), life forms and the spatial pattern of plant recovery. Results Plant species richness and abundance were significantly higher within the unburned forest and low fire severity areas one year after fire, compared to areas of high and moderate fire severity. Overall, nearly 50% of the species present in the unburned forest were not found in areas of high severity, including the tree Nothofagus pumilio. Rapid vegetative resprouting of pioneer species such as Chusquea culeou resulted in an aggregated spatial distribution of plants after fire. Conclusions Plant diversity and the abundance of Araucaria araucana and Nothofagus pumilio were reduced in areas of high fire severity one year after fire. Exotic species were more abundant within areas of low severity, being likely mediated by cattle browsing. Our research makes clear the potential changes in forest composition and structure if dominant tree species are not capable of recovering after fire. We recommend the exclusion of cattle within fire‐affected areas and planting Nothofagus pumilio in areas of high fire severity.

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