Browsing by Author "Weidberg, Nicolas"

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    Climate change in the coastal ocean: shifts in pelagic productivity and regionally diverging dynamics of coastal ecosystems
    (2022) Navarrete, Sergio A.; Barahona, Mario; Weidberg, Nicolas; Broitman, Bernardo R.
    Climate change has led to intensification and poleward migration of the Southeastern Pacific Anticyclone, forcing diverging regions of increasing, equatorward and decreasing, poleward coastal phytoplankton productivity along the Humboldt Upwelling Ecosystem, and a transition zone around 31 degrees S. Using a 20-year dataset of barnacle larval recruitment and adult abundances, we show that striking increases in larval arrival have occurred since 1999 in the region of higher productivity, while slower but significantly negative trends dominate poleward of 30 degrees S, where years of recruitment failure are now common. Rapid increases in benthic adults result from fast recruitment-stock feedbacks following increased recruitment. Slower population declines in the decreased productivity region may result from aging but still reproducing adults that provide temporary insurance against population collapses. Thus, in this region of the ocean where surface waters have been cooling down, climate change is transforming coastal pelagic and benthic ecosystems through altering primary productivity, which seems to propagate up the food web at rates modulated by stock-recruitment feedbacks and storage effects. Slower effects of downward productivity warn us that poleward stocks may be closer to collapse than current abundances may suggest.
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    Diel variability in the vertical distribution of coastal barnacle larvae in the Bay of Cartagena, Chile
    (2023) Bonicelli, Jessica; Jeneral, María J.; Bularz, Bryan; Weidberg, Nicolas; Plummer, Katalin Andra; Calderon Rivera, Ricardo Alonso; Cifuentes, Ursula; Alarcón, Darly; Navarrete Campos, Sergio Andrés
    Abstract Background Vertical distribution of zooplankton is an important biological factor that can modulate zooplankton transport, dispersal, and survival in the ocean. Seawater temperature and the associated formation of a thermocline can affect the spatial distribution of organisms in the water column and possibly modulate larval vertical distribution in coastal waters. In this study, we examined larval vertical distribution over small spatial scales where environmental conditions could exhibit strong and fairly predictable variability. Methods Diel variation in vertical distributions of barnacle larvae across the thermocline was characterized within the Bay of Cartagena of central Chile. Two intensive 21- and 24-h surveys were conducted in the northern (ECIM) and southern (CTGN) extremes of the bay in summer 2016 and spring 2017. In each survey, vertical tows were conducted at both sites every 3 h above and below the thermocline. Results During summer 2016, larval vertical distribution differed between taxa (balanids and verrucids), barnacle stages (nauplii, cyprids), and sites within the bay. Of all taxa analyzed Balanid nauplii at ECIM were more abundant in the bottom layer during the day and at the surface during the night, suggesting they can control their vertical distribution and follow a diel pattern.Acording to the results all barnacle larvae were found in diferent positions in the water column between day and night during periods of high stratification in this survey.. In spring 2017 all barnacle larvae were confined to the upper layer, despite the strength of stratification, potentially as a result of the intrusion of hypoxic water (< 2 mL L−1) at the bottom, which reached up to around 5 m deep. Conclusions We conclude that diel vertical distribution is not uniform across different barnacle larvae taxa and stages within the Bay of Cartagena and is not affected by stratification. Of all the taxa analyzed, only balanid nauplii showed a pattern of diel vertical migration across the thermocline under certain hydrographic conditions.
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    Larval transport in the upwelling ecosystem of central Chile : The effects of vertical migration, developmental time and coastal topography on recruitment
    (2018) Ospina-Alvarez, Andrés; Weidberg, Nicolas; Aiken, Christopher Michael; Navarrete C., Sergio
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    Wave-modulation of mussel daily settlement at contrasting rocky shores in central Chile: topographic regulation of transport mechanisms in the surf zone
    (2018) Weidberg, Nicolas; Bularz, Bryan; Lopez-Rodriguez, Sebastian; Andres Navarrete, Sergio