Examinando por Autor "Duarte, C."

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    Community disruption in small biogenic habitats: A coastal invader overcomes habitat complexity to alter community structure
    (Public Library of Science, 2020-10) Malyshev, A.V.; Flynn, P.T.; Cox, R.; Duarte, C.; Quijon, P.A.; Public Library of Science
    Non-indigenous species are often identified as threats to native species and communities. Yet, the mechanisms that enable many of these invaders to thrive and alter their newly invaded habitats are still not fully understood. This applies to habitats such as widespread sedimentary shorelines characterized by the presence of scattered biogenic clumps of blue mussels (Mytilus edulis) structurally more complex than bare sediments. In Atlantic Canada, some of these shorelines are numerically dominated by native mud crabs (Dyspanopeus sayi) but have been gradually invaded by the European green crab (Carcinus maenas). This study describes between-habitat (mussel clump vs. bare sediment) differences in density and diversity of invertebrates. It also tests the impact of juvenile green crabs in comparison to native mud crabs using two approaches: First, measuring habitat-related differences in these crabs' feeding rates on a common prey (soft-shell clams, Mya arenaria). Second, measuring their influence on invertebrate communities associated with mussel clumps. The results show that mussel clumps hold higher invertebrate density and diversity than surrounding sedimentary bottoms. In the laboratory, the feeding rates of native mud crabs were dependent on the type of habitat (sand flat > mussel clump), whereas those of green crabs were significantly higher and unrelated to the habitat in which predation occurred. In field experiments, juvenile green crabs were also the only predators that changed community structure in the mussel clump habitat. These results indicate that green crabs can cause a significant impact on native species and communities. Moreover, they suggest that the ability of this species to overcome the refuge provided by complex biogenic habitats for prey may represent an unexplored mechanism to explain this invader's expansion here and elsewhere. © 2020 Malyshev et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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    High pCO 2 levels affect metabolic rate, but not feeding behavior and fitness, of farmed giant mussel Choromytilus chorus
    (Inter-Research, 2018) Benítez, S.; Lagos, N.A.; Osores, S.; Opitz, T.; Duarte, C.; Navarro, J.M.; Lardies, M.A.
    Benthic habitats such as intertidal areas, sandy or rocky shores, upwelling zones, and estuaries are characterized by variable environmental conditions. This high variability of environmental stressors such as temperature, salinity, and pH/pCO 2 levels have been shown to impose restrictions on organismal performance. The giant mussel Choromytilus chorus forms intertidal and subtidal mussel beds in estuarine zones associated with fjords occurring in southern Chile and is an important aquacultural resource in Patagonia. In this study, we estimated the sensitivity of physiological traits and energy balance of C. chorus juveniles exposed to 3 pCO 2 treatments (500, 750, and 1200 μatm) for 30 d. Results showed that in acidified, high pCO 2 conditions, C. chorus juveniles had increased metabolic rates; however, other physiological traits (clearance and ingestion rates, ammonia excretion, absorption efficiency, growth rate, biomass production, net calcification, and dissolution rates) were not affected. These results suggest that when subjected to acidification, the adaptive response of C. chorus triggers tradeoffs among physiological traits that favor sustained feeding and growth in order to combat increased metabolic stress. As has been reported for other marine organisms, chronic exposure to variable pH/pCO 2 in their native habitats, such as estuarine zones, could explain the differential acclimatization capacity of giant mussels to cope with the increase in pCO 2 . Additionally, the fact that the mussels did not suffer from mortality indicates that increased pCO 2 levels may have chronic, but not lethal, effects on this species under these experimental conditions. © The authors 2017.
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    Living on a trophic subsidy: Algal quality drives an upper-shore herbivore’s consumption, preference and absorption but not growth rates
    (Public Library of Science, 2018-04) Quintanilla-Ahumada, D.; Quijón, P.A.; Navarro, J.M.; Pulgar, J.; Duarte, C.
    The transfer of seaweeds from subtidal bottoms to nearby intertidal rocky shores is a common but often overlooked phenomenon. Freshly detached seaweeds often represent critical trophic subsidies for herbivores living in upper-shore rocky intertidal areas, such as the marine snail Diloma nigerrima. This species relies on three species of seaweeds for food and displays feeding strategies to deal with a resource that is scarce and at times unpredictable. This study focused on the nutritional quality of freshly detached algae (Durvillaea antarctica, Lessonia spicata and Lessonia trabeculata) and measured Diloma nigerrima’s algal consumption rates in trials with and without choice. Absorption efficiency and growth of individual snails fed on each alga were also measured. Durvillaea antarctica had the highest nutritional quality and was the most consumed algae in both single and multiple-choice trials. Absorption efficiency was also highest for D. antarctica but growth rates of snails fed with this species were similar to those fed with the other algae. Combined, these results suggest that D. nigerrima has the ability to discriminate among seaweeds based on their nutritional quality. A potential increase in oxygen uptake when D. nigerrima is consuming the preferred food item is also proposed as a plausible hypothesis to explain the mismatch between snails’ preference and growth rate. These results aim to guide further studies on trophic subsidies and their role in coastal systems. © 2018 Quintanilla-Ahumada et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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    Macroscale patterns in body size of intertidal crustaceans provide insights on climate change effects
    (Public Library of Science, 2017-05) Jaramillo, E.; Dugan, J.E.; Hubbard, D.M.; Contreras, H.; Duarte, C.; Acuña, E.; Schoeman, D.S.
    Article Authors Metrics Comments Related Content Abstract Introduction Methods Results Discussion Supporting information Acknowledgments Author Contributions References Reader Comments (0) Media Coverage (0) Figures Abstract Predicting responses of coastal ecosystems to altered sea surface temperatures (SST) associated with global climate change, requires knowledge of demographic responses of individual species. Body size is an excellent metric because it scales strongly with growth and fecundity for many ectotherms. These attributes can underpin demographic as well as community and ecosystem level processes, providing valuable insights for responses of vulnerable coastal ecosystems to changing climate. We investigated contemporary macroscale patterns in body size among widely distributed crustaceans that comprise the majority of intertidal abundance and biomass of sandy beach ecosystems of the eastern Pacific coasts of Chile and California, USA. We focused on ecologically important species representing different tidal zones, trophic guilds and developmental modes, including a high-shore macroalga-consuming talitrid amphipod (Orchestoidea tuberculata), two mid-shore scavenging cirolanid isopods (Excirolana braziliensis and E. hirsuticauda), and a low-shore suspension-feeding hippid crab (Emerita analoga) with an amphitropical distribution. Significant latitudinal patterns in body sizes were observed for all species in Chile (21° - 42°S), with similar but steeper patterns in Emerita analoga, in California (32°- 41°N). Sea surface temperature was a strong predictor of body size (-4% to -35% °C-1) in all species. Beach characteristics were subsidiary predictors of body size. Alterations in ocean temperatures of even a few degrees associated with global climate change are likely to affect body sizes of important intertidal ectotherms, with consequences for population demography, life history, community structure, trophic interactions, food-webs, and indirect effects such as ecosystem function. The consistency of results for body size and temperature across species with different life histories, feeding modes, ecological roles, and microhabitats inhabiting a single widespread coastal ecosystem, and for one species, across hemispheres in this space-for-time substitution, suggests predictions of ecosystem responses to thermal effects of climate change may potentially be generalised, with important implications for coastal conservation.
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    Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)
    (Public Library of Science, 2013-07) Manríquez, P.; Jara, M.; Mardone, M.; Navarro, J.; Torres, R.; Lardies, M.; Vargas, C.; Duarte, C.; Widdicombe, S.; Salisbury, J.; Lagos, N.
    Background:Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation.Methodology/Principal Findings:The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 μatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 μatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab.Conclusions and Significance:These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.