UCN-CEAZA
Plasticity in feeding selectivity and trophic structure of kelp forest associated fishes from northern Chile.
Pérez-Matus, A., Pledger, S., Díaz, F., Ferry, L., & Vásquez, J.
One of the primary ways in which species interact with their environment is through foraging; thereby directly consuming some fraction of their surrounding habitat. The habitat itself, in turn, may dictate the types of foraging opportunities that are available to the inhabitants. To investigate the relationship between habitat availability and diet composition of habitat-associated fishes, we estimated the relative abundance of the potential sessile and mobile prey items and the diet of the fish species assemblage associated to kelp forest. Specifically, diet and feeding selectivity of the kelp-forest associated fish assemblage were determined by calculating Manly's alpha selectivity index. We determined the diet of kelp forest associated fishes and their foraging behavior by comparing prey availability with those items present in the stomachs of fishes captured by gill net and spear gun. We calculated the degree of dietary overlap among fishes from four locations along the northern coast of Chile. Results indicate that utilization of prey by predators is predominantly affected by potential prey availability. With the exception of the two carnivorous species such as Pinguipes chilensis (Valenciennes, 1883) and Paralabrax humeralis (Cuvier & Valenciennes, 1828), whose diet did not change among sites, all other kelp-associated fishes changed their dietary habitats to consistent with the availability of local resources. Benthic resources changed among the different study sites, which led to differing diets even in the same species from different locations. Eleven of the 12 kelp forest fishes also showed some selectively for benthic prey. We conclude that the ability of fishes to be plastic in their feeding preference and, therefore, partition the benthic resources may set adaptations to co-exist in a dynamic environment such as kelp forest.
Año: 2012
Palabras claves: Chile, Manly α, predation, trophic guilds, understory.
Referencia APA: Pérez-Matus, A., Pledger, S., Díaz, F., Ferry, L., & Vásquez, J. (2012). Plasticity in feeding selectivity and trophic structure of kelp forest associated fishes from northern Chile. Rev. Chil. Hist. Nat., 85(1), 29-48.
Bioeconomic effect from the size selection in red abalone intensive culture Haliotis rufescens as a production strategy.
Pérez, E., Araya, A., Araneda, M., & Zúñiga, C.
The variability in growth is a common characteristic in mollusks breeding. Effects rising from the variability in the individual growth rate and the consequent dispersion of sizes in cultivation are important in financial terms. To manage this heterogeneity many firms use size selection, which can happen in two stages: toward the end of the stage of growing, or in the phase of growing of seeds. A bioeconomic model simulating the operation of a firm producing red abalone was implemented in spreadsheets. The firm produces 70 tons yearly. The model was structured in three sub-models. A biological sub-model detailed a batch’s dynamics, in terms of survival and growth, considering individual variation of size around a central value for each age. A technological sub-model described raw materials, the quantity of food and the energy required. Finally, the simulation model is completed with an economic integrated sub-model, where net present value is calculated considering income and costs over the time. Results of the alternative production strategies (with or without selection) are assessed according to: quantity of larvae and necessary spawners to reach the desired level of production; net present value (NPV) and necessary time to recover the investment. The number of larvae was approximately 17 millions larger for the case of the strategy of production with sizes selection and 73% more of available spawners is required for this larger amount of larvae. In the short term, the size-selection strategy increases the production costs at the initial time, compared with the strategy without selection. However, in the long term, this strategy generates greater NPV. The span for investment recovery was shorter for the case of the strategy with size selection and living product (nearly 2,140 days) than frozen (nearly 2,232 days); while without sizes selection a 15-year simulation showed the investment is not recovered. Finally, could be verified that size selection can be an interesting strategy to explore, since it improves the financial result, the same way other more expensive technological changes would.
Año: 2012
Palabras claves: Bioeconomic effect, Red abalone, Size selection, Strategy.
Referencia APA: Pérez, E., Araya, A., Araneda, M., & Zúñiga, C. (2012). Bioeconomic effect from the size selection in red abalone intensive culture Haliotis rufescens as a production strategy. Aquaculture International, 20(2), 333-345.
Estimating rat predation on Humboldt Penguin colonies in north-central Chile.
Simeone, A. & Luna-Jorquera, G.
Rats (Rattus spp.) are among the most successful alien predators brought to islands by humans and have had devastating impacts on numerous seabird populations, but studies demonstrating rates of consumption and ecological impacts on penguins are scarce and mostly based on anecdotal evidence. We investigated the effects of rat predation on Humboldt Penguins (Spheniscus humboldti) by simulating unattended clutches with domestic Chicken eggs. Experiments were independently set at two Humboldt Penguin colonies in north (Pájaros Island, 29°S) and central Chile (Algarrobo Island, 33°S). At both colonies, eggs were primarily predated by rats (Rattus rattus = 70.8 % at Pájaros and Rattus norvegicus = 52.6 % at Algarrobo), and secondarily by Kelp Gulls (Larus dominicanus = 9.7 % at Pájaros and 15.8 % at Algarrobo). Significantly more eggs were predated at night. At both colonies, rates of rat and gull predation were highest within the first 12 h. Our study constitutes the first quantification of rats as important alien predators at Humboldt Penguin colonies. We suggest that rat presence at Humboldt Penguin colonies coupled with events that can cause temporary nest abandonment, such as human perturbation and El Niño events, may impact on the species’ breeding success. Eradication of rats is suggested to improve the nesting habitat of this and other threatened and endemic seabird species in the region.
Año: 2012
Palabras claves: Introduced species, Island conservation, Nest attendance, Alien predation, RattusPenguins
Referencia APA: Simeone, A. & Luna-Jorquera, G. (2012). Estimating rat predation on Humboldt Penguin colonies in north-central Chile. J Ornithol, 153(4), 1079-1085.
Estimaciones de crecimiento de Haliotis rufescens en cautiverio en el norte de Chile.
Pérez E., Eduardo P. AU - Araya, AndreaTI.
El crecimiento en acuicultura es indicador directo de productividad,permite predecir el desarrollo del cultivo y la cosecha, afecta indirectamente el desempeño de variables tecnológicas y determina el tiempo necesario para obtener individuos de un tamaño específico, lo cual condiciona el beneficio económico de un cultivo. Estas condiciones requieren la toma de datos y descripción adecuada del crecimiento de la especie cultivada. En este trabajo se evalúan tres alternativas de ajuste de parámetros de crecimiento a partir de información recopilada en un centro de cultivo de abalón rojo Haliotis rufescens en Coquimbo, Chile, donde se midieron durante un año individuos de 1,4-4,3 años, por intervalos de tamaño de 15-25, 26-35, 36-45, 46-55 y 56-65mm de longitud. Para analizar la consistencia en la estimación de crecimiento, se utilizaron tres modelos: la ecuación de von Bertalanffy (ECVB), la versión con crecimiento estacionalizado de ECVB y el modelo generalizado de crecimiento de Schnute y Richards. Los tres modelos resultaron ser confiables para longitudes en edades de 1,4-4,3 años, y las curvas de ajuste pasan a través del centro de la nube de puntos. Coincide esta etapa con la fase de crecimiento exponencial de los organismos. Con un criterio estrictamente estadístico la ECVB en su versión estacionalizada es la más ajustada, por una menor suma de cuadrados. Dado que las extrapolaciones hacia edades mayores y menores resultan más exactas con el modelo generalizado de crecimiento, se concluye que éste representó mejor el crecimiento de H. rufescens en las condiciones locales de cultivo.
Año: 2012
Palabras claves:
Referencia APA: Pérez E., Eduardo P. AU - Araya, AndreaTI. (2012). Estimaciones de crecimiento de Haliotis rufescens en cautiverio en el norte de Chile. Interciencia, VL - 37IS - 2AB.
Anthropogenic structures as a spatial refuge from predation for the invasive bryozoan Bugula neritina.
Dumont, C., Harris, L., & Gaymer, C.
Anthropogenic structures may play an important role in the marine invasion process by providing novel artificial habitats, often out of the reach of common benthic predators. A survey of piers in northern-central Chile revealed a change in the epibenthic assemblage on pilings at different distances from a rocky shore with abundant grazers and predators. Pilings on soft sediment, away from the rocky shore, were heavily colonized by the invasive bryozoan Bugula neritina. We therefore hypothesized that benthic predators may forage on pilings located on rocky bottom whereas pilings on soft sediment benefit from the absence of generalist benthic predators which do not occur on soft sediment. We examined piling communities using cages directly attached to pilings, where we included or excluded the sea urchin Tetrapygus niger and the rock shrimp Rhyncocinetes typus. Resultant communities differed substantially; a high percentage of bare space occurred in the presence of sea urchins, while turf algae dominated in the presence of shrimp. Both sea urchins and shrimp suppressed the colonization of the invasive B. neritina and, when acting together, totally prevented its recruitment. In contrast, invasive bryozoans colonized 95% of the available substratum in cages where predators were excluded. Our results show the important role of benthic generalist predators in limiting the establishment and spread of non-native species on anthropogenic structures. Further, this study highlights the unprecedented role of shrimp grazing in structuring hard-bottom communities.
Año: 2012
Palabras claves: Predation • Rock shrimp • Sea urchin • Invasive species • Fouling • Artificial hábitat.
Referencia APA: Dumont, C., Harris, L., & Gaymer, C. (2012). Anthropogenic structures as a spatial refuge from predation for the invasive bryozoan Bugula neritina. Marine Ecology Progress Series, 427, 95-103.
Conservación de la biodiversidad en Chile: Nuevos desafíos y oportunidades en ecosistemas terrestres y marinos costeros
Jorquera-Jaramillo, C., Vega, J., Aburto, J., Martínez-Tillería, K., F. Leon, M., & A. Pérez, M., Gaymer, C.F., & Squeo, F.A.
La pérdida de la biodiversidad producida por el crecimiento demográfico, la demanda por recursos y la actividad productiva es contradictoria con el reconocimiento de su importancia. En ecosistemas terrestres, el Sistema Nacional de Áreas Protegidas del Estado (SNASPE) contiene cerca del 19 % del territorio de Chile continental; aunque no representa todos los ecosistemas con especies amenazadas, puede ser complementado implementando nuevas áreas protegidas públicas (AP) y privadas (APP). El desarrollo de áreas marinas protegidas (AMP) es incipiente, y algunas iniciativas comparten la responsabilidad de conservación con los usuarios locales. En Chile, un conjunto de reglamentos, normas legales y tratados internacionales promueven distintas oportunidades de conservación en ecosistemas terrestres y marinos costeros, de las cuales emergen nuevos desafíos. Entre estos destacan, estandarizar la clasificación de especies según categorías de conservación en un protocolo internacional y optimizar las metodologías para seleccionar áreas prioritarias, ambos criterios indispensables para decidir qué y dónde conservar. Otro desafío es integrar el valor intrínseco de la biodiversidad con los servicios ecosistémicos que presta para instaurar una cultura participativa. Esto mejoraría la efectividad de las distintas estrategias de protección y uso sustentable de la biodiversidad al incorporar la educación y la participación ciudadana desde una perspectiva biocultural. La educación fomenta la conservación de la naturaleza al hacernos conscientes de nuestro entorno; mientras que la participación involucra a los ciudadanos como un actor más en la toma de decisiones, procurando la aplicación efectiva de las estrategias de conservación de la biodiversidad.
Año: 2012
Palabras claves: áreas marinas protegidas, áreas silvestres protegidas, conservación privada, participación ciudadana.
Referencia APA: Jorquera-Jaramillo, C., Vega, J., Aburto, J., Martínez-Tillería, K., F. Leon, M., & A. Pérez, M., Gaymer, C.F., & Squeo, F.A. (2012). Conservación de la biodiversidad en Chile: Nuevos desafíos y oportunidades en ecosistemas terrestres y marinos costeros. Rev. Chil. Hist. Nat., 85(3), 267-280.
Geochemistry of trace metals in shelf sediments affected by seasonal and permanent low oxygen conditions off central Chile, SE Pacific (∼36°S).
Muñoz, P., Dezileau, L., Cardenas, L., Sellanes, J., Lange, C., & Inostroza, J. et al.
Trace metals (Cd, U, Co, Ni, Cu, Ba, Fe, Mn), total organic carbon (TOC) and C and N stable isotope signatures (δ13C and δ15N) were determined in short sediments cores from the inner and outer shelf off Concepción, Chile (∼36°S). The objectives were to establish the effect of environmental conditions on trace metal distributions at two shelf sites, one affected by seasonal oxygenation and the other by permanent low oxygen conditions due to the presence of the oxygen minimum zone (OMZ). We evaluate trace metals as proxies of past changes in primary productivity and the bottom water oxygen regime. Concentrations of pore water sulfides and NH4+ were also measured as indicators of the main diagenetic pathways at each site. Our results for the inner shelf (seasonal suboxia) suggest that the oxidative state of the sediments responds to seasonal pulses of organic matter and that seasonal oxygenation develops during high and low primary productivity in the water column. Here, positive fluxes (to the water column) estimated from pore water concentrations of several elements were observed (Ba, Co, Ni, Fe and Mn). The less reduced environment at this site produces authigenic enrichment of Cu associated with the formation of oxides in the oxic surface sediment layer, and the reduction of U within deeper sediment sections occur consistently with negative estimated pore water fluxes. In the outer shelf sediments (permanent suboxia, OMZ site), negative fluxes (to the sediment) were estimated for all elements, but these sediments showed authigenic enrichments only for Cd, Cu and U. The short oxygenation period during the winter season did not affect the accumulation of these metals on the shelf. The distribution of Cu, Cd and U have been preserved within the sediments and the authigenic accumulation rates estimated showed a decrease from the deep sections of the core to the surface sediments. This could be explained by a gradual decrease in the strength of the OMZ in the last 100 years, in combination with periods of strong oxygenations during El Niño events.
Año: 2012
Palabras claves: Trace metals; Sediments; Oxygen minimum zone; Organic carbon; SE Pacific; Concepción shelf.
Referencia APA: : Muñoz, P., Dezileau, L., Cardenas, L., Sellanes, J., Lange, C., & Inostroza, J. et al. (2012). Geochemistry of trace metals in shelf sediments affected by seasonal and permanent low oxygen conditions off central Chile, SE Pacific (∼36°S). Continental Shelf Research, 33, 51-68.
Mining of EST-SSR from 454 pyrosequencing in the surf clam Mesodesma donacium (Lamark, 1818).
Aguilar-Espinoza, A., Guzmán-Riffo, B., Haye, P., & Gallardo-Escárate, C.
Novel simple sequence repeats (SSR) were identified from 454 transcriptome pyrosequencing ESTs in the surf clam Mesodesma donacium. From 7,734 ESTs annotated with SSR motives, 75 putative EST-SSRs were selected according their repetitive DNA sequence and functional annotation (Gene ontology), of these, 15 were characterized on 45 individuals of two wild populations located in two different biogeographic transition zones of the coast of Chile (30 and 42°S). Most loci were in Hardy–Weinberg equilibrium, and the polymorphic information content (PIC) ranged from 0.243 to 0.634. Pairwise Fst between sampled populations was estimated in 0.478. These EST-SSR markers promise to be useful for future management strategies of this overexploited species.
Año: 2012
Palabras claves: Pyrosequencing 454, Expressed sequence tag (EST), Microsatellite, Mesodesma donacium
Referencia APA: Aguilar-Espinoza, A., Guzmán-Riffo, B., Haye, P., & Gallardo-Escárate, C. (2012). Mining of EST-SSR from 454 pyrosequencing in the surf clam Mesodesma donacium (Lamark, 1818). Conservation Genet Resour, 4(4), 829-832.
The marine brooder Excirolana braziliensis (Crustacea: Isopoda) is also a complex of cryptic species on the coast of Chile.
Varela, A. & Haye, P.
Speciation is a direct consequence of isolated populations in taxa with low dispersal potential. The brooding crustacean Excirolana braziliensis, with a presumably wide geographic range of distribution (~16° N-41° S in the Pacific and ~19° N-35° S in the Atlantic), has been detected to correspond to cryptic species on the coast of Panama. Latitudinal variations in reproductive features in E. braziliensis have been attributed to phenotypic plasticity, however, the differences may be the result of divergent populations. Considering that the taxon has been reported to be a complex of cryptic species in other geographic areas and given the phenotypic differences detected along its distribution range, we hypothesized that E. braziliensis is a complex of species in the coast of Chile. We used partial cytochrome c oxidase subunit I (COI) sequences from 132 individuals with the diagnostic morphology of E. braziliensis collected along ~2200 km of coast to determine the genetic structure of E. braziliensis. Phylogenetic and phylogeographic analyses showed three distinct clades with 14 to 19 % of genetic divergence and high values of genetic differentiation. Intra and inter-clade divergence revealed the existence of a species complex of E. braziliensis on the coast of Chile, supporting growing evidence of the high abundance of cryptic species in marine invertebrate taxa.
Año: 2012
Palabras claves: cryptic species, genetic differentiation, genetic distance, marine peracarids, phylogenetics.
Referencia APA: Varela, A. & Haye, P. (2012). The marine brooder Excirolana braziliensis (Crustacea: Isopoda) is also a complex of cryptic species on the coast of Chile. Rev. Chil. Hist. Nat., 85(4), 495-502.
Effect of two temperatures on ammonia excretion rates of Seriolella violacea (Palm fish) juveniles under rearing conditions.
Nerici, C., Silva, A., & Merino, G.
Nitrogenous compounds can be toxic to aquatic animals, especially when they are reared for production purposes at high stocking densities. Seriolella violacea is a pelagic fish, native from the easterly South Pacific Ocean. This species has shown desirable behavioral and metabolic characteristics under captivity conditions, which leaded the Marine Fish Laboratory from the UCN to increase its efforts on the research and development to validate S. violacea as a new aquaculture option. Therefore, the objective of this study is to determine the excretion rates of palm fish juveniles weighing 300–500 g at two different temperatures: 14 °C and 18 °C. Total ammonia as nitrogen (TAN) excreted was 4.4 ± 0.9 and 7.1 ± 1.9 mg TAN/kg fish/h for 14 °C and 18 °C respectively. The experiments were carried out in a recirculating system operating as a farm-like situation. Tests were performed in 1000 L rearing tanks operating as open respirometers. The results of the present study indicate that TAN excretion rates on S. violacea juveniles, is temperature dependent. Data obtained in these experiments are valuable information for the engineering design of land based aquaculture systems for palm fish.
Año: 2012
Palabras claves: Seriolella violacea; Excretion rates; Ammonia; Recirculating aquaculture system; Water quality
Referencia APA: Nerici, C., Silva, A., & Merino, G. (2012). Effect of two temperatures on ammonia excretion rates of Seriolella violacea (Palm fish) juveniles under rearing conditions. Aquacultural Engineering, 46, 47-52.
Floating Seaweeds and Their Communities.
Rothäusler, E., Gutow, L., & Thiel, M.
A wide diversity of floating seaweeds is found in temperate and subpolar regions of the world’s oceans where sea surface currents and winds determine their traveling velocities and directions. The importance of floating seaweeds as dispersal agents for associated organisms and for the algae themselves varies depending on the supply from benthic source populations and on their persistence at the sea surface. Persistence of floating algae depends on water temperature, grazing activity, epifaunal load, and, to a lesser extent, on prevailing irradiance conditions. In temperate regions, persistence of floating algae is primarily limited by warm sea surface temperatures and high densities of motile and sessile epifauna whereas at higher latitudes algae can successfully compensate grazer-induced tissue loss by continuous growth at the prevailing low water temperatures. Accordingly, floating seaweeds can bridge large oceanic distances especially at high latitudes allowing for connectivity among distant benthic populations of algae and associated rafters.
Año: 2012
Palabras claves:
Referencia APA: Rothäusler, E., Gutow, L., & Thiel, M. (2012). Floating Seaweeds and Their Communities. Ecological Studies, 359-380.
Authentication of commercialized crab-meat in Chile using DNA Barcoding.
Haye, P., Segovia, N., Vera, R., Gallardo, M., & Gallardo-Escárate, C.
Authentication of commercialized marine products has become a market priority. Crustaceans are benthic marine resources highly exploited in Chile. Brachyuran crabs are of particular interest and in Chile are commercialized with different processing and presentations. Generally, Chilean brachyuran crab-meat commercial packages do not include taxonomic information, which in addition to the loss of diagnostic characters during the processing, impedes the identification of species being commercialized. The goal of this study was to determine which brachyuran species are being commercialized in the Chilean market using DNA Barcoding and phylogenetic analysis. For authentication of commercial crab-meat and DNA Barcoding a partial sequence of the Cytochrome Oxidase I (COI) gene of seven commercialized brachyuran species in Chile were used. For authentication, samples were obtained from seven commercial formats available on the local market in Coquimbo, Chile. Most commercial packages contained more than one species of crab. The Species detected in order of frequency are Metacarcinus edwardsii, Romaleon polyodon, Cancer porteri, Cancer plebejus, and Homalaspis plana. Mislabeling was detected in one of the commercial formats that declared including meat from Cancer species. The procedure presented herein, based on standard DNA Barcoding as well as phylogenetic analyses, can be used for the normative control of crab-meat processed products.
Año: 2012
Palabras claves: Food authentication; DNA Barcoding; Crab meat; Species identification; Mislabeling; Conservation genetics
Referencia APA: Haye, P., Segovia, N., Vera, R., Gallardo, M., & Gallardo-Escárate, C. (2012). Authentication of commercialized crab-meat in Chile using DNA Barcoding. Food Control, 25(1), 239-244.