Assessment of oxytetracycline baths as therapeutic treatment for the control of the agent of withering syndrome (WS) in red abalone (Haliotis rufescens)
Winkler, F., García, R., Valdivia, M., & Lohrmann, K.
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.
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)
Barros, J., Winkler, F., & Velasco, L.
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.
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
López, B., Macaya, E., Jeldres, R., Valdivia, N., Bonta, C., Tala, F., & Thiel, M.
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.
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
Honorato-Zimmer, D., Kruse, K., Knickmeier, K., Weinmann, A., Hinojosa, I., & Thiel, M.
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.
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
Nest building by a small mesograzer limits blade size of the giant kelp Macrocystis pyrifera
Poore, A., Gutow, L., Lörz, A., & Thiel, M.
Small herbivores are abundant on large marine macrophytes, but their impact on their hosts is poorly understood relative to large grazers such as urchins and fish. To limit the risks of predation, many marine mesograzers live within nests or burrows, potentially causing more damage to plants than predicted from consumption alone. To test whether the growth of large primary producers can be affected by modification of plant structures by small herbivores, we quantified the effect of the nest-building amphipod Pseudopleonexes lessoniae on blades of the giant kelp, Macrocystis pyrifera in New Zealand. Amphipods create their nests by rolling the blade margin in close proximity to the meristem. Blades with nests were 40% shorter than blades lacking nests and reduced in area by 55%. We examined the composition of amphipods inhabiting each nest to assess the temporal persistence of grazer aggregations. Nests were occupied by a single female or male–female pairs, and their newly hatched offspring. Analysis of offspring size distributions suggested that offspring dispersed from the maternal nest and did not remain to breed themselves. By concentrating physical damage and feeding on valuable tissues, these results indicate that even low numbers of small herbivores can cause localized impacts on the morphology and size of fast-growing algal blades. Predicting the consequences of this damage on larger scales will require understanding the spatial and temporal distribution of amphipod nests on giant kelp.
Referencia APA: Poore, A., Gutow, L., Lörz, A., & Thiel, M. (2018). Nest building by a small mesograzer limits blade size of the giant kelp Macrocystis pyrifera. Marine Biology, 165(12). doi: 10.1007/s00227-018-3444-6
Plastic Pirates sample litter at rivers in Germany – Riverside litter and litter sources estimated by schoolchildren
Kiessling, T., Knickmeier, K., Kruse, K., Brennecke, D., Nauendorf, A., & Thiel, M.
Rivers are an important source of marine anthropogenic litter, but the particular origins of riverine litter itself have not been well established. Here we used a citizen science approach where schoolchildren examined litter at riversides and identified possible sources at over 250 sampling spots along large and small rivers in Germany, during autumn 2016 and spring 2017. Litter densities have an overall median of 0.14, interquartile range 0–0.57 items m−2 and an overall average (±standard deviation) of 0.54 ± 1.20 litter items m−2. Litter quantities differed only little by sampling year. The principal litter types found were plastics and cigarette butts (31% and 20%, respectively), followed by glass, paper, and metal items, indicating recreational visitors as the principal litter source. At many sites (85%), accumulations of litter, consisting principally of cigarettes and food packaging, have been found. At almost all sampling sites (89%), litter potentially hazardous to human health has been observed, including broken glass, sharp metal objects, used personal hygiene articles and items containing chemicals. In the search for litter sources, the schoolchildren identified mainly people who use the rivers as recreational areas (in contrast to residents living in the vicinity, illegal dumping, or the river itself depositing litter from upstream sources). These results indicate the urgent need for better education and policy measures in order to protect riparian environments and reduce input of riverine litter to the marine environment.
Palabras claves: Plastic litter, Macrolitter, Freshwater, Source identification, Citizen science
Referencia APA: Kiessling, T., Knickmeier, K., Kruse, K., Brennecke, D., Nauendorf, A., & Thiel, M. (2019). Plastic Pirates sample litter at rivers in Germany – Riverside litter and litter sources estimated by schoolchildren. Environmental Pollution, 245, 545-557. doi: 10.1016/j.envpol.2018.11.025
First insight into the heritable variation and potential response to selection of phototaxis and locomotion behavior associated to the light/dark stimuli in the abalone Haliotis discus hannai
Defranchi, Y., Winkler, F., Farías, W., Herbinger, C., & Brokordt, K.
Abalones are especially susceptible to environmental lighting conditions. This factor greatly affects crucial biological process such as feeding rates, energy balance, physiological stress status, and consequently, growth and survival of farmed abalone. Most of these effects have been studied in the economically valuable abalone Haliotis discus hannai. The use of specific photoperiods, and/or light qualities and intensities, have been proposed as managing strategies to increase its production; however, for extensive off-shore or in intensive land-based farming systems, lighting conditions are not likely to be easily managed. Despite the great importance of the biological responses to the light/dark stimuli for abalone farming production, to the best of our knowledge the genetic control upon the variation associated behavioral traits have not been studied. Therefore, the aim of this study was to estimate the heritable variation and potential responses to selection for the phototaxis [i.e., displacement towards (positive) or against (negative) the light source] and locomotion behaviors associated to the intensity of the response (i.e., crawling speed and displacement distance) to the light/dark stimuli in juvenile H. discus hannai. Genetic and phenotypic correlations between these traits were also estimated. Results showed moderate but significant heritable variations for phototaxis (h2 = 0.15) and locomotion responses (h2 = 0.18–0.37); and significant positive genetic correlations among them. Expected gain responses to selection per generation (with a selection intensity of 2.06, i.e., selecting 5% of the individuals from a population) were moderate for phototaxis variation (16%) and high for locomotion responses variation (33–67 or 36–73%, depending on the model used for the estimations). As a consequence, the potential for reducing (or incrementing, depending on the breeding goal) the reactivity or the sensibility to the light stimulus by selective breeding is good, and can be an attractive way of indirectly improving growth, survival and general welfare of farmed H. discus hannai.
Palabras claves: Abalone phototaxis, Locomotion to light/dark, Phototaxis heritability, Abalone farming, Selective breeding, Haliotis discus hannai
Referencia APA: Defranchi, Y., Winkler, F., Farías, W., Herbinger, C., & Brokordt, K. (2019). First insight into the heritable variation and potential response to selection of phototaxis and locomotion behavior associated to the light/dark stimuli in the abalone Haliotis discus hannai. Aquaculture, 500, 645-650. doi: 10.1016/j.aquaculture.2018.10.065
Travelling light: Fouling biota on macroplastics arriving on beaches of remote Rapa Nui (Easter Island) in the South Pacific Subtropical Gyre
Rech, S., Thiel, M., Borrell Pichs, Y., & García-Vazquez, E.
Marine anthropogenic debris was sampled from two beaches on the remote South Pacific island Rapa Nui (Easter Island). Abundance, composition, and the attached fouling assemblages on stranded litter were analysed. Most litter (n = 172 items found) was composed of plastic material, and 34% of all litter items were fouled. The main fouling species was the encrusting bryozoan Jellyella eburnea. Transporting vectors were exclusively made from plastics and were mainly small items and fragments, probably stemming from the South Pacific Subtropical Gyre. We present the first report of Planes major, Halobates sericeus, and Pocillopora sp. on anthropogenic litter in the South Pacific.
Palabras claves: Non-indigenous species, Fouling assembly, Long-distance rafting, Marine anthropogenic litter, South Pacific Subtropical Gyre, Oceanic islands
Referencia APA: Rech, S., Thiel, M., Borrell Pichs, Y., & García-Vazquez, E. (2018). Travelling light: Fouling biota on macroplastics arriving on beaches of remote Rapa Nui (Easter Island) in the South Pacific Subtropical Gyre. Marine Pollution Bulletin, 137, 119-128. doi: 10.1016/j.marpolbul.2018.10.015
Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap
Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B.
Biotic interactions are central to the development of theory and concepts in community ecology; experimental evidence has shown their strong effects on patterns of population and community organization and dynamics over local spatial scales. The role of competition in determining range limits and preventing invasions at biogeographic scales is more controversial, partly because of the complexity of processes involved in species colonization of novel habitats and the difficulties in performing appropriate manipulations and controls.
We examined experimentally whether competition is likely to affect poleward range expansion hindering or facilitating the establishment of the limpet Scurria viridula along the south‐eastern Pacific rocky shore (30°S, Chile) in the region occupied by the congeneric S. zebrina. We also assessed whether competition with the “invader” or range‐expanding species could reduce individual performance of the “native” S. zebrina and depress local populations Geographic field surveys were conducted to characterize the abundance and identity of limpets along the south‐eastern Pacific coast from 18°S to 41°S, and the micro‐scale (few cm) spatial distribution across the range overlap of the two species. Field‐based competition experiments were conducted at the southern leading edge of the range of S. viridula (33°S) and at the northern limit of S. zebrina (30°S).
Field surveys showed poleward range expansion of S. viridula of ca. 210 km since year 2000, with an expansion rate of 13.1 km/year. No range shift was detected for S. zebrina. The resident S. zebrina had significant negative effects on the growth rate of the invading juvenile S. viridula, while no effect of the latter was found on S. zebrina. Spatial segregation between species was found at the scale of cms.
Our results provide novel evidence of an asymmetric competitive effect of a resident species on an invader, which may hamper further range expansion. No negative effect of the invader on the resident species was detected. This study highlights the complexities of evaluating the role of species interactions in setting range limits of species, but showed how interspecific competition might slow the advance of an invader by reducing individual performance and overall population size at the advancing front.
Palabras claves: Field experiments, Grazers, Pacific Ocean, Range overlap, Range shift, Transitional zone
Referencia APA: Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B. (2018). Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap. Journal Of Animal Ecology, 88(2), 277-289. doi: 10.1111/1365-2656.12917
The 2017 coastal El Niño
Takahashi, K.; Aliaga-Nestares, V.; Avalos, G.; Bouchon, M.; Castro, A.; Cruzado, L.; Dewitte, B.; Gutiérrez, D.; Lavado-Casimiro, W.; Marengo, J.; Martínez, A. G.; Mosquera-Vásquez, K.; Quispe, N.
The original concept of El Niño consisted of anomalously high sea surface temperature and heavy rainfall along the arid northern coast of Peru (Carranza 1891; Carrillo 1893). The concept evolved into the El Niño–Southern Oscillation (ENSO; Bjerknes 1969), although the original El Niño and the Southern Oscillation do not necessarily have the same variability (Deser and Wallace 1987), and the strong El Niño episode in early 1925 coincided with cold-to-neutral ENSO conditions (Takahashi and Martínez 2017). To distinguish the near-coastal El Niño from the warm ENSO phase, Peru operationally defines the “coastal El Niño” based on the seasonal Niño 1+2 SST anomaly (ENFEN 2012; L’Heureux et al. 2017). While recent attention has been
brought to the concept of ENSO diversity (e.g., “central Pacific” vs “eastern Pacific” events; Capotondi et al. 2015), the coastal El Niño represents another facet of ENSO that requires further study in terms of its mechanisms and predictability.
Referencia APA: Takahashi, K.; Aliaga-Nestares, V.; Avalos, G.; Bouchon, M.; Castro, A.; Cruzado, L.; Dewitte, B.; Gutiérrez, D.; Lavado-Casimiro, W.; Marengo, J.; Martínez, A. G.; Mosquera-Vásquez, K.; Quispe, N. (2018). The 2017 coastal El Niño. Bulletin of the American Meteorological Society. https://doi.org/10.1175/2018BAMSStateoftheClimate.1
Extreme El Niño Events
Dewitte, B., & Takahashi, K.
Every few years the tropical Pacific warms abnormally in association with a relaxation of the trade winds, a phenomenon known as the El Niño–Southern Oscillation (ENSO) that represents the strongest fluctuation of the global climate system. Although the contemporary observational record indicates that all El Niño events are not alike, differing in amplitude, warming pattern, and teleconnection, there is a class of events that stands out in terms of the societal and economical impacts: the extreme El Niño events that have occurred every 15–20 years. In this chapter, we propose an overview of the state of knowledge and of some current lines of research dedicated to extreme El Niño events. Building on the recently proposed concept of ENSO diversity, we further synthesize our current understanding of the nonlinear dynamics of this class of events and their expected evolution in a warmer climate and highlight some challenges in ENSO research.
Palabras claves: El Niño, ENSO diversity, External forcing, Global warming, Teleconnection.
Referencia APA: Dewitte, B., & Takahashi, K. (2019). Extreme El Niño Events. Tropical Extremes, 165-201. doi: 10.1016/b978-0-12-809248-4.00006-6
Is Precipitation a Good Metric for Model Performance?
Tapiador, F., Roca, R., Del Genio, A., Dewitte, B., Petersen, W., & Zhang, F.
Precipitation has often been used to gauge the performances of numerical weather and climate models, sometimes together with other variables such as temperature, humidity, geopotential, and clouds. Precipitation, however, is singular in that it can present a high spatial variability and probably the sharpest gradients among all meteorological fields. Moreover, its quantitative measurement is plagued with difficulties, and there are even notable differences among different reference datasets. Several additional issues sometimes lead to questions about its usefulness in model validation. This essay discusses the use of precipitation for model verification and validation and the crucial role of highly precise and reliable satellite estimates, such as those from NASA’s Global Precipitation Mission Core Observatory.
Referencia APA: Tapiador, F., Roca, R., Del Genio, A., Dewitte, B., Petersen, W., & Zhang, F. (2019). Is Precipitation a Good Metric for Model Performance?. Bulletin Of The American Meteorological Society, 100(2), 223-233. doi: 10.1175/bams-d-17-0218.1