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Modeling the reproductive impact of aquaculture-produced sexually fertile triploids on conspecific diploid populations

Autores:

Winkler, F., Concha, M., & Concha, C.

Resumen:

The use of artificially produced triploid (3n) organisms has been proposed as a strategy to produce total or partial sterility in a number of species in order to prevent the potential negative effects of escapees on the genetic structure and integrity of wild conspecific populations or to avoid having alien species become feral in a new environment. When infertility is incomplete, triploid organisms are able to produce gametes that compete with those produced by wild diploid populations or crops that share the same habitat during reproductive periods, which may adversely affect the reproductive success of the wild population. In the present study, a model was developed in order to estimate the effects of the production of gametes by triploid organisms on the reproductive efficiency of a sympatric diploid population of the same species. The chance of the production of balanced gametes by triploids rapidly reduced with the increase of haploid number of the species. It was concluded that, in most aquatic species, this effect depends on the relative contribution of gametes derived from triploid individuals ( pet), which is determined by the proportion of triploids in the population and their relative fecundity relative to normal diploids. The variation of the reproductive efficiency in a mixed population of diploids and triploids will be directly proportional to pet if only one sex is fertile in triploids but will have a logarithmic relationship if both sexes are fertile.

Año: 2019

Palabras claves: Triploids, Risk assessment, Reproductive success, Sterility, Chromosome manipulation, Fecundity

Referencia APA: Winkler, F., Concha, M., & Concha, C. (2019). Modeling the reproductive impact of aquaculture-produced sexually fertile triploids on conspecific diploid populations. Aquaculture Environment Interactions, 11, 205-211. doi: 10.3354/aei00308

Long-term persistence of the floating bull kelp Durvillaea antarctica from the South-East Pacific: Potential contribution to local and transoceanic connectivity

Autores:

Tala, F., López, B., Velásquez, M., Jeldres, R., Macaya, E., & Mansilla, A., Ojeda, J., Thiel, M.

Resumen:

Current knowledge about the performance of floating seaweeds as dispersal vectors comes mostly from mid latitudes (30°–40°), but phylogeographic studies suggest that long-distance dispersal (LDD) is more common at high latitudes (50°–60°). To test this hypothesis, long-term field experiments with floating southern bull kelp Durvillaea antarctica were conducted along a latitudinal gradient (30°S, 37°S and 54°S) in austral winter and summer. Floating time exceeded 200d in winter at the high latitudes but in summer it dropped to 90d, being still higher than at low latitudes (<45d). Biomass variations were due to loss of buoyant fronds. Reproductive activity diminished during long floating times. Physiological changes included mainly a reduction in photosynthetic (Fv/Fm and pigments) rather than in defence variables (phlorotannins and antioxidant activity). The observed long floating persistence and long-term acclimation responses at 54°S support the hypothesis of LDD by kelp rafts at high latitudes.

Año: 2019

Palabras claves: Chile, Durvillaea antarctica, Floating persistence, Rafting, Dispersal, Floating seaweeds, Temperature

Referencia APA: Tala, F., López, B., Velásquez, M., Jeldres, R., Macaya, E., & Mansilla, A., Ojeda, J., Thiel, M. (2019). Long-term persistence of the floating bull kelp Durvillaea antarctica from the South-East Pacific: Potential contribution to local and transoceanic connectivity. Marine Environmental Research, 149, 67-79. doi: 10.1016/j.marenvres.2019.05.013

How Does the Diversity of Divers Affect the Design of Citizen Science Projects?

Autores:

Hermoso, M., Martin, V., Stotz, W., Gelcich, S., & Thiel, M.

Resumen:

Divers have widely participated in citizen science (CS) projects and are one of the main groups of marine citizen scientists. However, there is little knowledge about profiles of, and incentives for potential divers to join CS projects. To date, most studies have focused on the SCUBA diving industry; nevertheless, there is a diversity of divers, not all using SCUBA, who engage in different activities during their dives. Differences in diver profiles could affect their willingness and ability to contribute to CS. In this study, we compare the diving profile, interests, preferences and motivations to participate in CS of five diver types (artisanal fishermen, recreational divers, instructors, scientific divers, and others). All divers have strong interests in participating in CS projects, with no major differences among diver types. In general, they are interested in a wide variety of themes related to CS but they prefer simple sampling protocols. Divers are motivated to participate in CS to learn about the sea and contribute to science. Some important differences among diver types were found, with artisanal fishermen having significantly more dive experience than other diver types, but less free time during their dives and limited access to some communication channels and technologies. These characteristics make them ideal partners to contribute their local ecological knowledge (LEK) to local CS projects. In contrast, recreational divers have the least experience but most free time during their dives and good access to cameras and communications channels, making them suitable partners for large-scale CS projects that do not require a high level of species knowledge. Instructors and scientific divers are well-placed to coordinate and supervise CS activities. The results confirm that divers are not all alike and specific considerations have to be taken into account to improve the contribution of each diver type to CS. The findings provide essential information for the design of different types of CS projects. By considering the relevant incentives and opportunities for diverse diver groups, marine CS projects will make efficient gains in volunteer recruitment, retention, and collaborative generation of knowledge about the marine environment.

Año: 2019

Palabras claves: Participatory science, subtidal, SCUBA, fishermen, recreational divers.

Referencia APA: Hermoso, M., Martin, V., Stotz, W., Gelcich, S., & Thiel, M. (2019). How Does the Diversity of Divers Affect the Design of Citizen Science Projects?. Frontiers In Marine Science, 6. doi: 10.3389/fmars.2019.00239

Uncovering population structure in the Humboldt penguin (Spheniscus humboldti) along the Pacific coast at South America

Autores:

Dantas, G., Oliveira, L., Santos, A., Flores, M., Melo, D., Simeone, A., González-Acuña, D., Luna-Jorquera, G., Le Bohec, C., Valdés-Velásquez, A., Cardeña, M., Morgante, J.S., Vianna, J.A.

Resumen:

The upwelling hypothesis has been proposed to explain reduced or lack of population structure in seabird species specialized in food resources available at cold-water upwellings. However, population genetic structure may be challenging to detect in species with large population sizes, since variation in allele frequencies are more robust under genetic drift. High gene flow among populations, that can be constant or pulses of migration in a short period, may also decrease power of algorithms to detect genetic structure. Penguin species usually have large population sizes, high migratory ability but philopatric behavior, and recent investigations debate the existence of subtle population structure for some species not detected before. Previous study on Humboldt penguins found lack of population genetic structure for colonies of Punta San Juan and from South Chile. Here, we used mtDNA and nuclear markers (10 microsatellites and RAG1 intron) to evaluate population structure for 11 main breeding colonies of Humboldt penguins, covering the whole spatial distribution of this species. Although mtDNA failed to detect population structure, microsatellite loci and nuclear intron detected population structure along its latitudinal distribution. Microsatellite showed significant Rst values between most of pairwise locations (44 of 56 locations, Rst = 0.003 to 0.081) and 86% of individuals were assigned to their sampled colony, suggesting philopatry. STRUCTURE detected three main genetic clusters according to geographical locations: i) Peru; ii) North of Chile; and iii) Central-South of Chile. The Humboldt penguin shows signal population expansion after the Last Glacial Maximum (LGM), suggesting that the genetic structure of the species is a result of population dynamics and foraging colder water upwelling that favor gene flow and phylopatric rate. Our findings thus highlight that variable markers and wide sampling along the species distribution are crucial to better understand genetic population structure in animals with high dispersal ability.

Año: 2019

Palabras claves: Penguins, Population genetics, Animal sociality, Chile (country), Gene flow, Islands, Seabirds, Haplotypes

Referencia APA: Dantas, G., Oliveira, L., Santos, A., Flores, M., Melo, D., Simeone, A., González-Acuña, D., Luna-Jorquera, G., Le Bohec, C., Valdés-Velásquez, A., Cardeña, M., Morgante, J.S., Vianna, J.A. (2019). Uncovering population structure in the Humboldt penguin (Spheniscus humboldti) along the Pacific coast at South America. PLOS ONE, 14(5), e0215293. doi: 10.1371/journal.pone.0215293

Unexpected population fragmentation in an endangered seabird: the case of the Peruvian diving-petrel

Autores:

Cristofari, R., Plaza, P., Fernández, C., Trucchi, E., Gouin, N., Le Bohec, C., Zavalaga, C., Alfaro-Shigueto, J., Luna-Jorquera, G.

Resumen:

In less than one century, the once-abundant Peruvian diving petrel has become the first endangered seabird of the Humboldt Current System (HCS). This small endemic petrel of the South American Pacific coast is now an important indicator of ongoing habitat loss and of the success of local conservation policies in the HCS - an ecoregion designated as a priority for the conservation of global biodiversity. Yet so far, poorly understood life history traits such as philopatry or dispersal ability may strongly influence the species’ response to ecosystem changes, but also our capacity to assess and interpret this response. To address this question, we explore the range-wide population structure of the Peruvian diving petrel, and show that this small seabird exhibits extreme philopatric behavior at the island level. Mitochondrial DNA sequences and genome-wide SNP data reveal significant isolation and low migration at very short distances, and provide strong evidence for questioning the alleged recovery in the Peruvian and Chilean populations of this species. Importantly, the full demographic independence between colonies makes local population rescue through migration unlikely. As a consequence, the Peruvian diving petrel appears to be particularly vulnerable to ongoing anthropogenic pressure. By excluding immigration as a major factor of demographic recovery, our results highlight the unambiguously positive impact of local conservation measures on breeding populations; yet at the same time they also cast doubt on alleged range-wide positive population trends. Overall, the protection of independent breeding colonies, and not only of the species as a whole, remains a major element in the conservation strategy for endemic seabirds. Finally, we underline the importance of considering the philopatric behavior and demographic independence of breeding populations, even at very fine spatial scales, in spatial planning for marine coastal areas.

Año: 2019

Palabras claves:

Referencia APA: Cristofari, R., Plaza, P., Fernández, C., Trucchi, E., Gouin, N., Le Bohec, C., Zavalaga, C., Alfaro-Shigueto, J., Luna-Jorquera, G. (2019). Unexpected population fragmentation in an endangered seabird: the case of the Peruvian diving-petrel. Scientific Reports, 9(1). doi: 10.1038/s41598-019-38682-9

Similarity in predator-specific anti-predator behavior in ecologically distinct limpet species, Scurria viridula (Lottiidae) and Fissurella latimarginata (Fissurellidae)

Autores:

Aguilera, M., Weiß, M., & Thiel, M.

Resumen:

Many marine gastropods show species-specific behavioral responses to different predators, but less is known about the mechanisms influencing differences or similarities in specific responses. Herein, we examined whether two limpet species, Scurria viridula (Lamarck, 1819) and Fissurella latimarginata (Sowerby, 1835), show species- and size-specific similarities or differences in their reaction to predatory seastars and crabs. Both S. viridula and F. latimarginata reacted to their main seastar predators with escape responses. In contrast, both limpets did not flee from common crab predators, but, instead, fastened to the rock. All tested size classes of both limpet species reacted in a similar way, escaping from seastars, but clamping onto the rock in response to crabs. Limpets could reach velocities sufficient to outrun their specific seastar predators, but they were not fast enough to escape crabs. Experiments with limpets of different shell conditions (with and without shell damage) indicated that F. latimarginata with a damaged shell showed “accommodation movements” (slow movements away from stimulus) in response to predatory crabs. In contrast, intact F. latimarginata and all S. viridula (intact and damaged) clamped the shell down to the substratum. The response details suggest that the keyhole limpet F. latimarginata is more sensitive to predators (faster reaction time, longer escape distances, and higher proportion of reacting individuals) than S. viridula, possibly because the morphology of F. latimarginata (the relationship of its shell size and structure to its total body size) makes this species more vulnerable to predation. Our study suggests that chemically mediated effects of seastar and crab predators result in contrasting behavioral responses of both limpet species, independent of their habitat and morphology. Despite the different characteristics of the limpet species and the identity of predators, the limpets react in comparable ways to similar predator types.

Año: 2019

Palabras claves:

Referencia APA: Aguilera, M., Weiß, M., & Thiel, M. (2019). Similarity in predator-specific anti-predator behavior in ecologically distinct limpet species, Scurria viridula (Lottiidae) and Fissurella latimarginata (Fissurellidae). Marine Biology, 166(4). doi: 10.1007/s00227-019-3485-5

Aves marinas varadas en la bahía de Coquimbo, norte de Chile: ¿Qué especies y cuántas mueren?

Autores:

Portflitt Toro, M., Miranda Urbina, D., & Luna Jorquera, G.

Resumen:

El monitoreo de las aves varadas en las playas puede proporcionar información sobre sus causas de muerte, tales como la captura incidental en actividades de pesca o derrames de petróleo. Durante un año fue monitoreada mensualmente la Bahía de Coquimbo, norte de Chile para cuantificar el número de aves marinas varadas. Se encontraron 395 aves marinas muertas de las cuales 382 fueron identificadas y agrupadas en 21 especies. Las especies más abundantes fueron los piqueros con 115 individuos (30%), el cormorán guanay con 83 individuos (22%) y la gaviota dominicana con 65 individuos (17%). Las especies más abundantes y frecuentes fueron las que anidan en el Sistema Costero de Coquimbo. La mortalidad afecta principalmente a las aves marinas que se alimentan de la anchoveta, que es el principal recurso objetivo de la pesca con redes de cerco. Se sugiere que la mortalidad incidental causada por la pesca es crónica y relativamente constante durante el año. Se requiere un programa de monitoreo a largo plazo para mejorar la estimación de la mortalidad y los factores que influyen en la interacción de las aves marinas con las artes de pesca.

Monitoring of seabirds stranded on beaches can provide information about their causes of death, such as bycatch in fishing activities or oil spills. During a year we monthly monitored the Coquimbo Bay, north Chile, to quantify the number of seabirds and species stranded. We found 395 dead seabirds, of which 382 were identified and grouped into 21 species. The most abundant were the Peruvian booby with 115 individuals (30%), the Guanay cormorant with 83 individuals (22%) and the Kelp gull with 65 individuals (17%). The most abundant and frequent species were those nesting in the Coastal System of Coquimbo. Mortality mainly affected seabirds that feed on anchoveta, which is the main target resource of purse seine fishing. We suggest that the incidental mortality caused by fishing is chronic and relatively constant during the year. A long-term monitoring program is needed to better estimate the mortality and the factors that influence the interaction of seabirds with fishing gears.

Año: 2018

Palabras claves: Strandings; seabirds; Suliformes; Coastal System of Coquimbo; Chile

Referencia APA: Portflitt Toro, M., Miranda Urbina, D., & Luna Jorquera, G. (2018). Aves marinas varadas en la bahía de Coquimbo, norte de Chile: ¿Qué especies y cuántas mueren?. Retrieved 24 July 2019, from Rev. biol. mar. oceanogr. vol.53 no.2, http://dx.doi.org/10.22370/rbmo.2018.53.2.1292

Struggling with social-ecological mismatches in marine management and conservation at Easter Island

Autores:

Aburto, J., & Gaymer, C.

Resumen:

In Easter Island, most of fisheries regulations are top-down implemented by the central fisheries authority located ~4000 km eastwards. This could generate problems in regulations compliance, given the cultural differences between the western worldview and Polynesian culture of Easter Island. A total of 18 issues that must be considered previously to an intervention in the island were identified. Four of them scored the highest difference between Rapanui and public services representatives. Among them, “Integrating traditions and culture” had a little priority for the public services representatives, but was the most important for the Rapanui. According to the public services representatives in Easter Island and local fishermen, there is a little compliance with regulations related to fisheries and, due to cultural aspects, it is not possible to enforce regulations and apply sanctions. The low compliance with fisheries regulations is due to the lack of representativeness of regulations. Interventions in the island are based on western worldview that does not fit with social and ecological domains of social-ecological system. A flexible governance system, based on decision making at local level in line with local tradition is needed to navigate to a resource management and conservation in Easter Island.

Año: 2018

Palabras claves:

Referencia APA: Aburto, J., & Gaymer, C. (2018). Struggling with social-ecological mismatches in marine management and conservation at Easter Island. Marine Policy, 92, 21-29. doi: 10.1016/j.marpol.2018.01.012

Assessment of oxytetracycline baths as therapeutic treatment for the control of the agent of withering syndrome (WS) in red abalone (Haliotis rufescens)

Autores:

Winkler, F., García, R., Valdivia, M., & Lohrmann, K.

Resumen:


Withering Syndrome (WS) is a lethal disease that affects abalone species in both wild and farmed populations. This infection, caused by the rickettsial-like intracellular organism (RLO) Candidatus Xenohaliotis californiensis, can severely impair the normal development of affected animals, and ultimately, their survival. The most common line of action against the WS has been the use of antibiotics, specifically oxytetracycline (OTC), administered via intramuscular injection and per os via medicated feed. In the present study, we have assessed the effectiveness of OTC baths as therapeutic treatment for the control of the WS agent in H. rufescens. Clinical signs of infection were monitored for 11 months in treated juveniles, in addition to feed consumption rate, growth patterns and gonad development. Abalones were asymptomatic until the end of the experiment, when a small number of non-treated animals exhibited clinical signs of infection. Gonad maturity was not observed. OTC treated animals grew significantly less than their non-treated counterparts, being 4.3% shorter and 13.6% lighter at the end of the experiment. They also displayed negative allometry, i.e. for the same shell length, they were lighter than non-treated groups. Furthermore, the weight of muscle and soft tissues in OTC treated animals was lighter than in the other groups, while no differences were found in shell weight. The feed consumption rate was the same for all groups, thus the observed growth patterns cannot be attributed to a decreased feed intake. One possible explanation is that antibiotic treatment may have impacted gut microflora, thus preventing efficient nutrient digestion and absorption and, indirectly, reducing growth. Prevalence of RLOs causing WS (WS-RLO) and the variant form (RLOv), infected with a bacteriophague and non virulent, were significantly lower in the OTC-treated group than in the other groups. Similar results were observed for the mean intensity of RLOv, while for WS-RLO, the intensity in the OTC-treated group was higher, although not statistically significant, than the rest of the groups. These observations may be the consequence of an increased bacterial sensitivity to OTC effects associated with the phage infection or faster reproduction of WS-RLOs than RLOv after OTC treatment. Our results let us infer that the prophylactic use of OTC in abalone to avoid the negative effects of WS on abalone farms could have an undesired negative effect on the biological control exerted by the phage on the bacteria after OTC treatment.

Año: 2018

Palabras claves: Withering syndrome, Rickettsial-like organism, Hyperparasitic phage, Antibiotic, Growth, RLO

Referencia APA: Winkler, F., García, R., Valdivia, M., & Lohrmann, K. (2018). Assessment of oxytetracycline baths as therapeutic treatment for the control of the agent of withering syndrome (WS) in red abalone ( Haliotis rufescens ). Journal Of Invertebrate Pathology, 153, 109-116. doi: 10.1016/j.jip.2018.02.019

Heritability, genetic correlations and genotype-environment interactions for growth and survival of larvae and post-larvae of the Caribbean scallop, Argopecten nucleus (Mollusca: Bivalvia)

Autores:

Barros, J., Winkler, F., & Velasco, L.

Resumen:

The Caribbean scallop Argopecten nucleus is a species with a great potential for commercial aquaculture in the Caribbean given its fast growth and the availability of culture technology. However, its production relies completely on hatchery-reared seed, and the survival in early stages, particularly during the settling process, is the main limitation for this activity to become cost effective. Thus, in order to assess the feasibility of improving survival of larvae and post-larvae of A. nucleus through genetic selection without affecting growth, it was estimated the heritability and the genotype-environment interactions for such traits, as well as the genetic correlations between them. These parameters were estimated based on intraclass correlations of 40 full-sib families (10 half-sib families) at 1, 11 and 75 days post fertilization. Heritability values were very high for the post-larvae survival (0.49), while it was low and not significant for larvae survival (≤0.07) and medium to high for growth traits of larvae and post-larvae (>0.3). The traits analyzed in post-larvae exhibited significant genotype-environment interactions in relation to culture depth in the sea. No significant genetic correlations between the measured traits were found. The results suggest the existence of an important genetic component in the variation of post-larval survival, and larval and post-larval growth, as well as a high potential response to direct genetic selection, especially for post-larval survival (50% increase per generation), without affecting the growth traits.

Año: 2018

Palabras claves: Shell length, Shell height, Post-larvae recovery, Genetic improvement, Selective breeding, Genetic gain, Pectinid

Referencia APA: Barros, J., Winkler, F., & Velasco, L. (2018). Heritability, genetic correlations and genotype-environment interactions for growth and survival of larvae and post-larvae of the Caribbean scallop, Argopecten nucleus (Mollusca: Bivalvia). Aquaculture, 495, 948-954. doi: 10.1016/j.aquaculture.2018.06.047

Spatio-temporal variability of strandings of the southern bull kelp Durvillaea antarctica (Fucales, Phaeophyceae) on beaches along the coast of Chile—linked to local storms

Autores:

López, B., Macaya, E., Jeldres, R., Valdivia, N., Bonta, C., Tala, F., & Thiel, M.

Resumen:

Availability of floating seaweeds may depend on the seasonal cycles of benthic populations, but our ability to predict temporal patterns of stranded biomasses is still limited. Season-dependent, local storms favor detachment of seaweeds from the substratum, which can be reflected in the stranded biomasses on adjacent beaches after these events. Hence, we hypothesized that seaweed strandings are positively correlated with storm intensity. Using as a model the southern bull kelp Durvillaea antarctica (Chamisso) Hariot, a species frequently found in seaweed strandings in Chile, bimonthly surveys were carried out on three beaches: Pichicuy (32° S), Itata Norte (36° S), and Curiñanco (39° S) for 3 years (2014 to 2017). Stranded biomass, total length, and wet weight of specimens were quantified and related to local storms (using the Douglas sea scale). Stranded biomasses decreased in the spring months of each year, being higher in Pichicuy and Curiñanco than Itata Norte. Regression models showed a better fit with recent storms in Curiñanco compared to other beaches. An interannual decrease of beach-cast raft size was observed, showing smaller specimens in Itata Norte than those in Pichicuy and Curiñanco. Reduced habitat availability and the exploitation of natural beds in the central zone (34°–37° S) might explain the decrease of biomasses and sizes of stranded bull kelps. Also, oceanographic features at intermediate (i.e., local winds and currents) and large scales (i.e., El Niño) can help to explain the temporal variability, particularly in spring and summer. Our results suggest that harvesting of stranded bull kelps might be most favorable in summer and autumn.

Año: 2018

Palabras claves: Bull kelps, Douglas sea scale, Floating seaweeds, Sandy beaches, Strandings

Referencia APA: López, B., Macaya, E., Jeldres, R., Valdivia, N., Bonta, C., Tala, F., & Thiel, M. (2018). Spatio-temporal variability of strandings of the southern bull kelp Durvillaea antarctica (Fucales, Phaeophyceae) on beaches along the coast of Chile—linked to local storms. Journal Of Applied Phycology, 31(3), 2159-2173. doi: 10.1007/s10811-018-1705-x

Inter-hemispherical shoreline surveys of anthropogenic marine debris – A binational citizen science project with schoolchildren

Autores:

Honorato-Zimmer, D., Kruse, K., Knickmeier, K., Weinmann, A., Hinojosa, I., & Thiel, M.

Resumen:

Anthropogenic marine debris (AMD) is a global problem and the identification of its sources is essential for adequate mitigation strategies. Herein we examined whether AMD density and composition differed between two countries with contrasting socio-economic backgrounds and marine litter sources (i.e. Chile and Germany). In nationwide beach litter surveys, we used a citizen science approach with schoolchildren and their teachers. Litter densities were substantially higher in Chile than in Germany. The different geographic zones surveyed in both countries showed strong grouping tendencies according to their main economic activities (tourism, shipping, fisheries/aquaculture), major litter sources, and AMD composition, in terms of dominance and diversity of AMD types. The results suggest that beach litter composition can be used as a simple proxy to identify AMD sources, and also that law enforcement and education can help mitigate the problem; however, for efficient solutions, production and consumption of plastics must be reduced.

Año: 2018

Palabras claves: Marine plastic litter, Beach surveys, Litter composition, Litter sources, Citizen science, Schoolchildren

Referencia APA: Honorato-Zimmer, D., Kruse, K., Knickmeier, K., Weinmann, A., Hinojosa, I., & Thiel, M. (2019). Inter-hemispherical shoreline surveys of anthropogenic marine debris – A binational citizen science project with schoolchildren. Marine Pollution Bulletin, 138, 464-473. doi: 10.1016/j.marpolbul.2018.11.048