Browsing by Author "Carlos Castilla, Juan"

Now showing 1 - 9 of 9
  • No Thumbnail Available
    Item
    Behavioural traits of competent Concholepas concholepas (loco) larvae
    (2011) Manriquez, Patricio H.; Carlos Castilla, Juan
    Swimming activity of competent Concholepas concholepas (Bruguiere, 1789) larvae, under different photoperiod, water turbulence and settlement cues were investigated in laboratory experiments. At night, larvae mainly swam to the water surface and then sank passively to the bottom. During the day, regardless of the photoperiod, larvae mainly stayed on the bottom, occasionally exhibiting upward movements. During the swimming period, larvae displayed the capacity to adhere to floating substrata through several mechanisms, including the secretion of a long and sticky mucous thread, air bubble capture or taking advantage of the water tension. The presence of C. concholepas prey, such as the mussel Semimytilus algosus and the chthamaloid barnacle Notochthamalus scabrosus, significantly influenced the swimming activity of competent C. concholepas larvae, inducing them to stay close to the bottom where prey were present. C. concholepas prey also triggered the initiation of larvae crawling, a characteristic of the early benthic life of C. concholepas. Although our laboratory experiments are proxies of nature, they are in good agreement with field observations in shallow nearshore areas (< ca. 0.5 km from shore) that recorded higher abundances of competent C. concholepas larvae (which are often associated with floating substrata) captured by surface planktonic tows during the night rather than day. Similarly, competent C. concholepas larvae abundances were higher in tows through inner nearshore foam slicks than in non-slick areas. The results suggest that the presence of endogenous swimming behaviour in these larvae may be a key factor enhancing adherence to floating substrata. The laboratory discovery of vertical buoyancy provides new information leading to a better understanding of the distribution and abundance patterns of these larvae in inner nearshore waters.
  • No Thumbnail Available
    Item
    Darwin taxonomist: Barnacles and shell burrowing barnacles
    (2009) Carlos Castilla, Juan
    This bibliographic review revisits circumstances in which the wharf, shell burrowing barnacle, Cryptophialus minutus, was first collected by Charles Darwin in southern Chile, in 1836. Further, explores how its collection marked Darwin's taxonomical interest in Cirripedia. A short review analyzes the initial number of extant species of Cirripedia, as described by Darwin and the present situation, with emphasis on recent collections of C. minutus in the southern tip of South America.
  • No Thumbnail Available
    Item
    Effects of predation risk on survival, behaviour and morphological traits of small juveniles of Concholepas concholepas (loco)
    (2013) Manriquez, Patricio H.; Elisa Jara, Maria; Opitz, Tania; Carlos Castilla, Juan; Lagos, Nelson A.
    In marine systems, water-borne chemical cues may induce anti-predator responses that influence not only performance and survival of the prey, but also population dynamics and species interaction. The early life stages of marine species with complex life-cycles settle into unpredictable habitats, and therefore may be expected to exploit reliable chemical cues emanating from both prey and predators in order to promote plastic responses to the local conditions. We compared the behavioural responses, survival and growth of early ontogenetic stages of Con cholepas concholepas exposed to the risk of predation by natural predators that commonly co-occur with it in the intertidal: the crabs Homalaspis plana and Acanthocyclus hassleri and the asteroid Heliaster helianthus. Y-maze experiments indicated that C. concholepas use water-borne cues both to detect prey and deploy strong anti-predator behaviour. Our results indicate lower survival rates of small specimens of C. concholepas when they were maintained in the direct presence of predators rather than under control conditions. Similar results and growth inhibition were found with C. concholepas exposed to seawater in which the predators had been maintained. Quantification of feeding activity and shell thickness in response to predation risk indicated lower prey consumption and thicker shells when C. concholepas were exposed to crab odours compared to control conditions. Our results suggest that this behavioural receptiveness to water-borne cues may be responsible, in part, for the early plasticity of species with complex life-cycles such C. concholepas under natural conditions, facilitating predator avoidance and thus enhancing survival.
  • No Thumbnail Available
    Item
    Exploring relationships between gender and collective action in artisanal fisher associations of Central Chile
    (2022) Vargas Poulsen, Camila; Rivera, Antonella; Ortiz, Veronica; Carlos Castilla, Juan; Estevez, Rodrigo A.; Reyes-Mendy, Francisca; Gelcich, Stefan
    fisher associations have experienced a shift towards gender inclusivity over the past decade. We used the social-ecological systems framework developed by Elinor Ostrom to explore relationships between gender and collective action. Questionnaires were used to determine (1) motivations to join an association, (2) socio-demographic information, (3) perceptions on key collective action dimensions around leadership and norms within the association, and (4) perceived social performance. Surveys targeted artisanal fisher associations in Chile with varying gender compositions: exclusively male members, exclusively female members, mixed-gender led by a man, and mixed -gender led by a woman. Our results show that women and men have distinct motivations to join an association. Women are primarily motivated by a sense of belonging, while men are mainly motivated by the possibility of an increase in income. Furthermore, associations comprised of women displayed higher valuations on leadership, entrepreneurship, and participation in activities. This likely led to the significantly higher performance of associations that incorporated women (either women-only or mixed gender) in efficiency (30.1%- 40.3% higher) and cooperation (13.8%-30. 8% higher). Our results extend the social-ecological systems framework towards understanding the role of gender in collective action for fisheries management and specifically contribute to build knowledge and implement novel policy which considers gender in artisanal fisheries in Chile.
  • No Thumbnail Available
    Item
    Fertilization efficiency and gamete viability in the ascidian Pyura praeputialis in Chile
    (2010) Manriquez, Patricio H.; Carlos Castilla, Juan
    In Chile, the ascidian Pyura praeputialis is an introduced species that occurs in intertidal and subtidal habitats restricted to Antofagasta Bay where it commonly forms extensive colonies that dominate mainly the rocky intertidal. Here we report the results of laboratory experiments conducted to determine the patterns of gamete spawning, and the consequences of the mode of reproduction, sperm age and sperm concentration on fertilization success. Our laboratory experiments indicate that the synchronous release of gametes takes place after the specimens are exposed to air, which is then followed by the formation of a biofoam in the rearing containers. Self fertilization with gametes obtained either by stripping or natural spawning failed to produce larvae or normal development, which occurred only when allosperm were used. Under laboratory conditions, fertilization success significantly decreased with sperm age and sperm concentration. Under field conditions, we recorded a negative effect of distance from areas with biofoam associated with spawning individuals on fertilization success. These findings suggest that it is selectively advantageous for this broadcast species to release gametes at low tide or after a period of emersion followed by biofoam formation. We suggest that this mechanism might have evolved to mitigate the difficulties of fertilization in turbulent aerated seawater, and to maximize fertilization success of short-lived gametes.
  • No Thumbnail Available
    Item
    Fifty years from the publication of the first two papers on Chilean rocky intertidal assemblages: Honoring Professor Eric R. Guiler
    (2008) Carlos Castilla, Juan
    In this paper I review and honor the scientific rocky intertidal findings made by the Australian investigator Professor Eric R. Guiler, who visited Chile in 1955. He pioneered this line of research in the country and published the first two papers on the Chilean rocky intertidal biotic zonation for northern and central Chile: Guiler 1959a, b. I remark Guiler's main observations and hypotheses about the structure and dynamics of these systems. I highlight the observations made by Guiler inside the Bay of Antofagasta and contrast them with recent experimental ecological work carried out inside this bay. Finally, I refer to the extensive and significant contributions made by Chilean researchers in this line of research and international recognition.
  • No Thumbnail Available
    Item
    Geographic variation in trace-element signatures in the statoliths of near-hatch larvae and recruits of Concholepas concholepas (loco)
    (2012) Manriquez, Patricio H.; Galaz, Sylvana P.; Opitz, Tania; Hamilton, Scott; Paradis, George; Warner, Robert R.; Carlos Castilla, Juan; Labra, Fabio A.; Lagos, Nelson A.
    Spatial variation of trace elements in calcified structures (otoliths, statoliths, and shells) has been used to track the movements of individuals among habitats, and connectivity between marine populations. In the present study, we used laser ablation-inductively coupled plasma mass spectrometry to quantify the concentrations of trace elements in statoliths of prehatch larvae and recruits of the gastropod Concholepas concholepas from 3 regions in Chile. We also examined spatial variation in chemical signatures deposited during larval life and at the time of settlement in intertidal habitats. We found significant differences between 3 geographic regions in the trace element concentrations recorded in natal statoliths of near-hatch larvae and in natal core and edge areas of recruit statoliths. Discriminant function analysis indicates that natal signatures of near-hatch larvae and the cores and edges of recruit statoliths show spatial segregation among regions. High levels of reclassification success of larvae to the origin region suggest potential for assigning recruits to the corresponding matching region. Concentrations of trace elements in the natal cores of recruit statoliths fell relatively close but did not overlap with the discriminant space occupied by larvae, and at regional scales the pattern of geographic variation of recruit statoliths resembles that of larval statoliths. This suggests population grouping and little population interchange at this regional scale. Assessing population stocks and connectivity of this species at smaller scales along the Chilean coast will only be possible with more finely structured sampling and a better understanding of temporal variation in the chemical environment.
  • Thumbnail Image
    Item
    Territorial User Rights for Fisheries as Ancillary Instruments for Marine Coastal Conservation in Chile
    (WILEY-BLACKWELL, 2012) Gelcich, Stefan; Fernandez, Miriam; Godoy, Natalio; Canepa, Antonio; Prado, Luis; Carlos Castilla, Juan
    Territorial user rights for fisheries have been advocated as a way to achieve sustainable resource management. However, few researchers have empirically assessed their potential as ancillary marine conservation instruments by comparing them to no-take marine protected areas. In kelp (Lessonia trabeculata) forests of central Chile, we compared species richness, density, and biomass of macroinvertebrates and reef fishes among territorial-user-right areas with low-level and high-level enforcement, no-take marine protected areas, and open-access areas in 42 100-m subtidal transects. We also assessed structural complexity of the kelp forest and substratum composition. Multivariate randomized permutation tests indicated macroinvertebrate and reef fish communities associated with the different access regimes differed significantly. Substratum composition and structural complexity of kelp forest did not differ among access regimes. Univariate analyses showed species richness, biomass, and density of macroinvertebrates and reef fishes were greater in highly enforced territorial-user-right areas and no-take marine protected areas than in open-access areas. Densities of macroinvertebrates and reef fishes of economic importance were not significantly different between highly enforced territorial-user-right and no-take marine protected areas. Densities of economically important macroinvertebrates in areas with low-level enforcement were significantly lower than those in areas with high-level enforcement and no-take marine protected areas but were significantly higher than in areas with open access. Territorial-user-right areas could be important ancillary conservation instruments if they are well enforced.
  • Thumbnail Image
    Item
    Young People Are Changing Their Socio-Ecological Reality to Face Climate Change: Contrasting Transformative Youth Commitment with Division and Inertia of Governments
    (MDPI, 2022) Pena-Vega, Alfredo; Cohen, Marianne; Manuel Flores, Luis; Le Treut, Herve; Lagos, Marcelo; Carlos Castilla, Juan; Gaxiola, Aurora; Marquet, Pablo
    This paper contributes to a critical re-reading of the notion of climate services. It does so by problematizing the discontinuity between young people's commitment to climate change, and the lack of a common vision regarding climate policy among governments. In this essay, youth commitment is characterized in terms of participation in the Global Youth Climate Pact (GYCP, 2015-2022). Here, young people share projects from their own high schools and communities and participate in a citizen consultation. Most projects have achieved a good success score, increasing over the years, especially for those carried out in emerging and developing countries. Some of them were presented at the COPs. In contrast, a textual analysis of intended nationally determined contributions (INDC) illustrates divergent understandings of the Paris Agreement and exemplifies the poor results of governmental climate diplomacy. This study establishes the need to closely monitor early warning signs of climate change in conjunction with high schools and school communities. The initiatives of young people are building a civic and planetary awareness for climate change in contrast with governmental division and inertia. In this sense, climate services, directed to young people, could contribute to design a sustainable future. We approach the practices, attitudes, and commitments of young people from the angle of cooperation rather than a moral vision of responsibility. Particularly, we propose a dialogical link between the treatment of climate issues and its effects on the constitution of networks, notably as they relate to practices of action, that is, the way in which distinct groups of young people develop relationships with their environments, organize themselves, and act and transform reality.