Browsing by Author "Bularz, Bryan"

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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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    Effects of harvesting on subtidal kelp forests (Lessonia trabeculata) in central Chile
    (2022) Bularz, Bryan; Fernandez, Miriam; Subida, Maria Dulce; Wieters, Evie A.; Perez-Matus, Alejandro
    The systematic degradation of marine ecosystems is a global phenomenon that has important and diverse consequences including biodiversity loss and reduced ecosystem service provisions. In temperate regions, subtidal kelp forests are dominant ecosystems in rocky coasts, subjected to the influence of local-scale stressors and regional environmental variation. For example, kelps within the Humboldt Current System are at risk of degradation from live-harvesting by fisheries. However, limited information exists regarding the long-term consequences of kelp harvesting, which, in turn, limits the ability to provide effective management and conservation efforts. Here, we examined the ecosystem-level consequences of the artisanal subtidal Lessonia trabeculata fishery along the coast of central Chile during a 2-year period, assessing (1) the change in adult and juvenile L. trabeculata density within harvested and nonharvested (control) plots (similar to 90 m(2)), (2) the impact of L. trabeculata harvesting on reef fish and macroinvertebrate assemblages, and (3) the change in density of the most abundant L. trabeculata-associated species. The experiment was conducted over a 2-year period, from December 2016 to May 2019. Approximately 90% of L. trabeculata was removed by an experienced kelp fisherman in experimental plots. After 2 years, L trabeculata and its associated community showed a lack of recovery in the harvested plots. Within these plots, the average abundance of the rock shrimp, Rhynchocinetes typus, and the herbivorous snail, Tegula tridentata, was greater than in nonharvested plots and the pattern persisted over the study period. The difference in abundance of associated species may be key to the (lack of) recovery of L. trabeculata forests. Our study highlights the impact of L. trabeculata harvesting on associated fauna; however, significant knowledge gaps remain regarding the capacity and time frame to reestablish the original biomass of L trabeculata, as well as its associated fauna. The management of L. trabeculata fisheries needs to account for ecosystem-wide impacts in order to better manage and protect vital coastal ecosystems.
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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