UCN-CEAZA
Coalescence in wild organisms of the intertidal population of Lessonia berteroana in northern Chile: management and sustainability effects.
Rodríguez, D., Oróstica, M., & Vásquez, J.
Lessonia berteroana is the subject of 85 % of the total harvest of Chilean brown seaweeds, representing close to 10 % of total kelp biomass worldwide harvested for alginic acid extraction. Frequent incidence of coalescent holdfasts was detected in natural populations, and this process gives rise to fused sporophytes. This study presents the coalescence events in natural populations in northern Chile. During 2011, in natural intertidal populations, 435 target sporophytes of different sizes were observed weekly and 63.90 % (278) showed physical signs of coalescent disks. We were able to distinguish five fusion modes depending on the number and size of each of the participant sporophytes and their spatial distribution. There was a progressive decrease of density and an increase in the number of stipes of each sporophyte over time. Two processes were recognized: active fusion of juvenile sporophytes and passive fusion of adult and senescent sporophytes. However, most of the coalescence processes were detected in juvenile sporophytes with a holdfast diameter of 0.5 to 2 cm. The minimum distance between pairs of coalescing sporophytes was 0.5 cm, and the maximum distance was 13 cm. For good harvesting practices, it is recommended that plants with over 20 cm holdfast diameter are harvested from natural populations because over this size, all of the plants have reproduced. Coalescence events would produce plants with legal size requirement; however, these plant units would not be reproductive, affecting the sustainability of this important coastal resource.
Año: 2013
Palabras claves: Lessonia berteroana population, Coalescence process, Management and sustainability.
Referencia APA: Rodríguez, D., Oróstica, M., & Vásquez, J. (2013). Coalescence in wild organisms of the intertidal population of Lessonia berteroana in northern Chile: management and sustainability effects. J Appl Phycol, 26(2), 1115-1122.
Host-use patterns and factors influencing the choice between anemone and urchin hosts by a caridean shrimp.
Ory, N., Dudgeon, & Thiel, M.
Small marine decapods often associate with other invertebrates in order to gain protection from predators. However, the factors that influence host choice by symbionts, such as shrimps, are poorly understood but may have important implications for the distribution and abundance of these mesoconsumers. In Hong Kong, the rhynchocinetid shrimp Rhynchocinetes brucei uses two alternative hosts: an urchin (Diadema setosum) and an anemone (Entacmaea quadricolor). We examined the association between R. brucei and its anemone and urchin hosts in the field and laboratory, investigating host choice and host fidelity. Underwater surveys on shallow rocky reefs in Hong Kong revealed that shrimps were rarely found outside refuges, such as crevices and holes, unless they were associated with anemones and urchins. Shrimps were more frequently associated with urchins than with anemones, although anemones were more abundant within the survey area. Host-choice experiments in the laboratory confirmed that, when given a choice, shrimps avoided open areas and associated with anemones, urchins or artificial refuges. Shrimps overwhelmingly chose urchins over artificial refuges, but did not show any clear preference for anemones over refuges. When offered a choice, shrimps displayed fidelity for their original host species (i.e. the host with which they were associated when collected from the field), suggesting that they imprinted upon the host. Host-imprinting may allow symbionts to efficiently relocate their original host species after separation (e.g. following nocturnal foraging trips) thereby, perhaps, reducing the risk of predation. However, host preference by R. brucei was facultative because shrimps would associate with an unfamiliar host when their original host was unavailable. This flexibility may allow shrimps to respond to local variability in host abundance.
Año: 2013
Palabras claves: Host-imprinting; Host selection; Refuge; Rocky reefs; Shrimp.
Referencia APA: Ory, N., Dudgeon, & Thiel, M. (2013). Host-use patterns and factors influencing the choice between anemone and urchin hosts by a caridean shrimp. Journal Of Experimental Marine Biology And Ecology, 449, 85-92.
Seasonal variation in floating persistence of detached Durvillaea antarctica (Chamisso) Hariot thalli.
Graiff, A., Karsten, U., Meyer, S., Pfender, D., Tala, F., & Thiel, M.
Several large kelp species are capable of long-distance dispersal via rafting. However, seasonal changes in environmental conditions at the sea surface may variably affect the physiological status of the floating thalli; challenging conditions during summer may accelerate disintegration and cause rapid sinking. We used the bull kelp Durvillaea antarctica from northern-central Chile (30°S) to test seasonal variation in floating persistence. Experiments with tethered specimens were conducted in all seasons to assess how variable environmental conditions influence the morphology and photosynthetic characteristics of floating D. antarctica. Floating specimens stayed afloat at the surface for more than 1 month during moderate environmental conditions that prevailed in winter, spring, and fall. However, higher water temperatures and intense solar radiation in summer resulted in significant biomass losses and rapid disintegration of the floating kelps; consequently, they sank within <1 month. These strong seasonal effects were reflected in decreasing maximal quantum yield as well as in maximum relative electron transport rates of photosynthesis. Understanding physiological responses of floating algae is important because increasing global temperatures and shifts in solar radiation may strongly affect the survival of floating algae, potentially reducing the distances and frequencies of rafting dispersal.
Año: 2013
Palabras claves: Durvillaea antarctica; floating persistence; rafting; temperature; UV radiation.
Referencia APA: Graiff, A., Karsten, U., Meyer, S., Pfender, D., Tala, F., & Thiel, M. (2013). Seasonal variation in floating persistence of detached Durvillaea antarctica (Chamisso) Hariot thalli. Botanica Marina, 56(1).
Raymond T. Bauer, Recipient of the Crustacean Society excellence in research award.
Thiel, M.
Año: 2013
Palabras claves:
Referencia APA: Toonen, R., Wilhelm, T., Maxwell, S., Wagner, D., Bowen, B., & Sheppard, C., Terorokog, T., Moffittc, R., Gaymer, C.F., et al. (2013). One size does not fit all: The emerging frontier in large-scale marine conservation. Marine Pollution Bulletin, 77(1-2), 7-10.
Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits’ expression.
Pacheco, A., Uribe, R., Thiel, M., Oliva, M., & Riascos, J.
Post-larval dispersal along the sediment–water interface is an important process in the dynamics of macrobenthic populations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in low energy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms (diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersing assemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed different trap types that capture benthic organisms with specific modes of dispersal (active emergence and passive water column drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlement from the water column). Our results show that even though there were common species in all types of traps, the post-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abundant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported invertebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersal was driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits “small size, swimming, hard exoskeleton, free living and surface position” were associated to water column and bedload dispersal. This study highlights the importance of (i) the water–sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along the bottom or through the water column.
Año: 2013
Palabras claves: Emerging Benthos; Bottom Currents; Soft-bottom Communities; Humboldt Current Ecosystem.
Referencia APA: Pacheco, A., Uribe, R., Thiel, M., Oliva, M., & Riascos, J. (2013). Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits' expression. Journal Of Sea Research, 77, 79-92.
Learning about TURFs and natural variability: Failure of surf clam management in Chile.
Aburto, J. & Stotz, W.
Territorial User Rights for Fisheries (TURF) is considered an appropriate tool for small-scale fishery management. In Chile a TURFs system called Management Exploitation Areas for Benthic Resources (Áreas de Manejo y Explotación de Recursos Bentónicos-AMERB) were developed as a solution for the fishery crisis of Concholepas concholepas, a hard bottom snail. The success of these AMERBs led to its widespread application across different fisheries resources and social-ecological contexts, among them the surf clam Mesodesma donacium which has a highly variable population. Traditionally, fishermen followed the sporadically appearing M. donacium beds, migrating along the coast, a behavior now suppressed under the AMERB regime. We examined the dynamics of the M. donacium fishery, evaluating the performance of the AMERB system for its sustainable exploitation. Fishermen extracted surf clams based on monthly quotas, which were conservative. Despite this, after three years the fishery of M. donacium within the AMERB collapsed because of lack of recruitment and high natural mortality. The resulting low abundances made the fishery unattractive, causing the abandonment of the AMERB. This suggests that implementation of an AMERB system must integrate knowledge of the spatial scales over which different clam beds (subpopulations) are connected. While still ignoring the structure of the metapopulation, as occurs at present for M. donacium stocks in Chile, it could be evaluated to increase capture during the periods of boom, taking advantage of surf clams that will disappear in any case due to natural mortality. A spatial reserve within each clam bed could also be established in order to conserve the unknown but potentially important role of the subpopulation for the metapopulation.
Año: 2013
Palabras claves:
Referencia APA: Aburto, J. & Stotz, W. (2013). Learning about TURFs and natural variability: Failure of surf clam management in Chile. Ocean & Coastal Management, 71, 88-98.
Identification of self-reported user behavior, education level, and preferences to reduce littering on beaches – A survey from the SE Pacific.
Eastman, L., Núñez, P., Crettier, B., & Thiel, M.
Beach litter is an environmental, health, and economic burden around the world. Reducing or eliminating beach litter requires a sound understanding of the beach users that often produce the litter. Education has consistently been promulgated as positively influencing environmental behaviors, though this is not well-investigated for the beach environment. In this citizen science project, school children surveyed the population in their various coastal communities in Chile, garnering over 900 responses nationwide. The survey included several domains concerning the problem of beach litter: demographic profiles of beach users (including education level), their littering behavior, and their disposition and preference towards solutions. Nearly half of the participants admitted to having littered in some way while the majority of those with college or graduate school education said they never litter, significantly more than lower education groups. A vast majority of the population endorsed a fine for beach littering. Community-level environmental education (for the entire population, including litterers) was the most common solution proposed by beach users, but was significantly less popular the more often the participant self-reported littering. Based on these results it is suggested that beach managers create multifaceted and localized solutions that involve several strategies (environmental education, fines, more trash cans) and also take into account the demographic profile of the beach users (including their education level), which could influence their littering behavior and support of potential solutions.
Año: 2013
Palabras claves:
Referencia APA: Eastman, L., Núñez, P., Crettier, B., & Thiel, M. (2013). Identification of self-reported user behavior, education level, and preferences to reduce littering on beaches – A survey from the SE Pacific. Ocean & Coastal Management, 78, 18-24
Isolation with differentiation followed by expansion with admixture in the tunicate Pyura chilensis.
Haye, P. & Muñoz-Herrera, N.
For Pyura chilensis, partial sequences of the gene COI revealed three highly supported haplogroups that diverged 260000 to 470000 years ago. Two haplogroups currently are widely distributed and sympatric, while one is dominant only in Los Molinos (LM, 39°50′S). The two widespread COI haplogroups underwent a geographic expansion during an interglacial period of the Late Pleistocene ca. 100000 years ago. The nuclear gene was less divergent and did not resolve the COI haplogroups. Bayesian clustering of the nuclear gene’s SNPs revealed that individuals from the two widespread COI haplogroups were mostly assigned to two of the three detected clusters and had a marked degree of admixture. The third cluster predominated in LM and showed low admixture. Haplotypic diversity of both genes was very high, there was no isolation by distance, and most localities were genetically undifferentiated; only LM was consistently differentiated with both genes analyzed.
Año: 2013
Palabras claves: Phylogeography, Genetic structure, Dispersal potential, Short-lived larvae, Connectivity, Biofouling, COI, Elongation Factor 1 alpha.
Referencia APA: Haye, P. & Muñoz-Herrera, N. (2013). Isolation with differentiation followed by expansion with admixture in the tunicate Pyura chilensis. BMC Evol Biol, 13(1), 252.
Effects of sympatric predatory crabs Romaleon polyodon and Cancer plebejus (Decapoda, Brachyura, Cancridae) on sublittoral macrobenthic communities.
Pacheco, A., Thiel, M., Uribe, R., Campos, L., & Riascos, J.
Although large crabs are recognized as important sediment disturbers influencing the structure of benthic communities, the role of dominant predatory crabs in soft-bottom habitats along the Humboldt Current Ecosystem, remains largely unknown. A field study was conducted, hypothesizing that the digging activity of these predators disturbs the habitat thereby leading to a reduction in individual abundance, biomass and species richness; these changes result in a modified structure of macrobenthic communities. A directed sampling (crab pits vs. reference areas) showed significant reductions in total abundances in pits compared to reference areas, but no differences were observed in taxonomic richness or benthic biomass. Short-term cage experiment showed significant decreases in total abundance and biomass of macroinvertebrates in predator inclusion treatments compared to exclusions and controls. In consequence, our results confirmed that burrowing activities and the generation of small disturbed sediment patches influence the community structure. These results highlight the importance of large cancrid crabs in soft-bottom habitats, where their modification of the physical configuration of the sediment affects community structure over small spatial scales. Crabs are thus an important source of spatial heterogeneity of the sea-floor landscape. This ecological role must be considered in management strategies of the extensive artisanal fishery for these crabs, as current evidence is showing increasing populations of intermediate predators (like cancrid crabs) in many benthic habitats in response to the depletion of top predators.
Año: 2013
Palabras claves: Bioturbation; Burrowing; Cage experiment; Northern Chile; Predation; Small-scale disturbance; Soft bottom.
Referencia APA: Pacheco, A., Thiel, M., Uribe, R., Campos, L., & Riascos, J. (2013). Effects of sympatric predatory crabs Romaleon polyodon and Cancer plebejus (Decapoda, Brachyura, Cancridae) on sublittoral macrobenthic communities. Journal Of Experimental Marine Biology And Ecology, 443, 147-154.
Role of shellfish hatchery as a reservoir of antimicrobial resistant bacteria.
Miranda, C., Rojas, R., Garrido, M., Geisse, J., & González, G.
The main aim of this study was to determine the occurrence of resistant bacteria in florfenicol-treated and untreated scallop larval cultures from a commercial hatchery and to characterize some selected florfenicol-resistant strains. Larval cultures from untreated and treated rearing tanks exhibited percentages of copiotrophic bacteria resistant to florfenicol ranging from 0.03% to 10.67% and 0.49–18.34%, respectively, whereas florfenicol resistance among oligotrophic bacteria varied from 1.44% to 35.50% and 3.62–95.71%, from untreated and treated larvae, respectively. Florfenicol resistant microbiota from reared scallop larvae mainly belonged to the Pseudomonas and Pseudoalteromonas genus and were mainly resistant to florfenicol, chloramphenicol, streptomycin and co-trimoxazole. This is the first study reporting antimicrobial resistant bacteria associated to a shellfish hatchery and the results suggest that a continuous surveillance of antimicrobial resistance even in absence of antibacterial therapy is urgently required to evaluate potential undesirable consequences on the surrounding environments.
Año: 2013
Palabras claves: Florfenicol; Heterotrophic bacteria; Antimicrobial resistance; Scallop culture; Chile; Hatchery.
Referencia APA: Miranda, C., Rojas, R., Garrido, M., Geisse, J., & González, G. (2013). Role of shellfish hatchery as a reservoir of antimicrobial resistant bacteria. Marine Pollution Bulletin, 74(1), 334-343.
Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): A study supported by a citizen science project.
Hidalgo-Ruz, V. & Thiel, M.
The accumulation of large and small plastic debris is a problem throughout the world's oceans and coastlines. Abundances and types of small plastic debris have only been reported for some isolated beaches in the SE Pacific, but these data are insufficient to evaluate the situation in this region. The citizen science project "National Sampling of Small Plastic Debris” was supported by schoolchildren from all over Chile who documented the distribution and abundance of small plastic debris on Chilean beaches. Thirty-nine schools and nearly 1000 students from continental Chile and Easter Island participated in the activity. To validate the data obtained by the students, all samples were recounted in the laboratory. The results of the present study showed that the students were able to follow the instructions and generate reliable data. The average abundance obtained was 27 small plastic pieces per m2 for the continental coast of Chile, but the samples from Easter Island had extraordinarily higher abundances (>800 items per m2). The abundance of small plastic debris on the continental coast could be associated with coastal urban centers and their economic activities. The high abundance found on Easter Island can be explained mainly by the transport of plastic debris via the surface currents in the South Pacific Subtropical Gyre, resulting in the accumulation of small plastic debris on the beaches of the island. This first report of the widespread distribution and abundance of small plastic debris on Chilean beaches underscores the need to extend plastic debris research to ecological aspects of the problem and to improve waste management.
Año: 2013
Palabras claves: Small plastic debris; Anthropogenic litter; Plastics; Citizen Science; SE Pacific; Chile; Easter Island; Marine debris.
Referencia APA: Hidalgo-Ruz, V. & Thiel, M. (2013). Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): A study supported by a citizen science project. Marine Environmental Research, 87-88, 12-18.
Effect of florfenicol and oxytetracycline treatments on the intensive larval culture of the Chilean scallop Argopecten purpuratus (Lamarck, 1819).
Miranda, C., Rojas, R., Abarca, A., & Hurtado, L.
The administration of antimicrobials to control bacterial pathologies in Chilean scallop hatcheries is a frequent practice, but their effects on these cultures remained unknown. This study was undertaken to obtain information on the effect of the administration of florfenicol and oxytetracycline on the growth, survival and bacterial content of scallop larvae under farming conditions. Florfenicol-treated cultures exhibited high survival rates (44% after 17 days of culture), whereas cultures not treated or treated with oxytetracycline collapsed after 11 days of culture. Surprisingly, no significant differences in the heterotrophic (Tukey test; P = 0.226) and Vibrio (Tukey test; P = 0.666) concentrations between the oxytetracycline-treated and untreated larval cultures were observed. Otherwise, florfenicol administered directly into rearing tanks produced significantly higher larval growth (Tukey test; P = 0.0001) and survival (Tukey test; P = 0.011) than bath treatment. When 2 and 4 mg L−1 of florfenicol were compared, no significant differences in growth (t-test; P = 0.4596) and survival (Tukey test; P = 0.057) were observed, suggesting that a concentration of 2 mg L−1 is sufficient to ensure larval production. The present results demonstrate the efficacy of florfenicol-based therapy to increase larval survival and growth at commercial scale and prompt the necessity to standardize its use in Chilean scallop hatcheries.
Año: 2013
Palabras claves: Bacteria; florfenicol; Chilean scallop; shellfish bacteriology; Argopecten purpuratus ; Chile.
Referencia APA: Miranda, C., Rojas, R., Abarca, A., & Hurtado, L. (2013). Effect of florfenicol and oxytetracycline treatments on the intensive larval culture of the Chilean scallop Argopecten purpuratus (Lamarck, 1819). Aquaculture Research, 45(1), 16-30.