The combined effects of ocean warming and acidification on shallow-water meiofaunal assemblages
Lee, M. R., Torres, R., & Manríquez, P. H.
Climate change due to increased anthropogenic CO2 in the atmosphere is causing an increase in seawater temperatures referred to as ocean warming and a decrease in seawater pH, referred to as ocean acidification. The meiofauna play an important role in the ecology of marine ecosystems and the functions they provide. Using microcosms, meiofaunal assemblages were exposed to two temperatures (15 and 19 °C) and two pHs (pCO2 of 400 and 1000 ppm), both individually and in combination, for a period of 90 days. The hypothesis that increased temperature will increase meiofaunal abundance was not supported. The hypothesis that a reduced pH will reduce meiofaunal abundance and species richness was supported. The combination of future conditions of temperature and pH (19 °C and pCO2 of 1000 ppm) did not affect overall abundance but the structure of the nematode assemblage changed becoming dominated by a few opportunistic species.
Palabras claves: Meiofauna, Nematodes, Ocean warming, Ocean acidification, Microcosms, Chile
Referencia APA: Lee, M. R., Torres, R., & Manríquez, P. H. (2017). The combined effects of ocean warming and acidification on shallow-water meiofaunal assemblages. Marine Environmental Research, 131, 1-9. http://dx.doi.org/10.1016/j.marenvres.2017.09.002
Interactions between kelp spores and encrusting and articulated corallines: recruitment challenges for Lessonia spicata
Parada, G. M., Martínez, E. A., Aguilera, M. A., Oróstica, M. H., & Broitman, B. R.
Intertidal kelps like Lessonia spicata (Laminariales) dominate low intertidal habitats, where they coexist with morphologically diverse coralline seaweeds. We show that crustose and articulated coralline algae have contrasting effects on the settlement and recruitment of this kelp species. Crustose coralline algae significantly inhibited the settlement of kelp spores, while they readily settled on the genicula of articulated coralline algae. This pattern was observed both in laboratory experiments and in field experiments conducted in the low intertidal zone at three locations. Field surveys confirmed that L. spicata juveniles were significantly more likely to be found on articulated corallines than on crustose corallines. This pattern held in field surveys at 10 sites, where primary space occupancy of L. spicata showed a significant negative correlation with the cover of crustose coralline algae in 3 out of 4 years, across all sites. Our results provide an important ecological clue to the processes determining recruitment limitation for ecologically and economically important seaweeds, and support conservation and management actions.
Palabras claves: Facilitation; Intertidal kelps; Seaweed interactions; Spore settlement
Referencia APA: Parada, G. M., Martínez, E. A., Aguilera, M. A., Oróstica, M. H., & Broitman, B. R. (2017). Interactions between kelp spores and encrusting and articulated corallines: recruitment challenges for Lessonia spicata. Botanica Marina, 60(6), 619-625. https://doi.org/10.1515/bot-2017-0010
Benthic communities under anthropogenic pressure show resilience across the Quaternary
Martinelli, J. C., Soto, L. P., González, J., & Rivadeneira, M. M.
The Southeast Pacific is characterized by rich upwelling systems that have sustained and been impacted by human groups for at least 12 ka. Recent fishing and aquaculture practices have put a strain on productive coastal ecosystems from Tongoy Bay, in north-central Chile. We use a temporal baseline to determine whether potential changes to community structure and composition over time are due to anthropogenic factors, natural climatic variations or both. We compiled a database (n = 33 194) with mollusc species abundances from the Mid-Pleistocene, Late Pleistocene, Holocene, dead shell assemblages and live-sampled communities. Species richness was not significantly different, neither were diversity and evenness indices nor rank abundance distributions. There is, however, an increase in relative abundance for the cultured scallop Argopecten, while the previously dominant clam Mulinia is locally very rare. Results suggest that impacts from both natural and anthropogenic stressors need to be better understood if benthic resources are to be preserved. These findings provide the first Pleistocene temporal baseline for the south Pacific that shows that this highly productive system has had the ability to recover from past alterations, suggesting that if monitoring and management practices continue to be implemented, moderately exploited communities from today have hopes for recovery.
Palabras claves: Conservation palaeobiology, Molluscs, Aquaculture, Overfishing, Temporal baseline, South Pacific
Referencia APA: Martinelli, J. C., Soto, L. P., González, J., & Rivadeneira, M. M. (2017). Benthic communities under anthropogenic pressure show resilience across the Quaternary. Royal Society Open Science, 4(9), 170796. http://dx.doi.org/10.1098/rsos.170796
Development and characterization of the first 16 microsatellites loci for Panulirus pascuensis (Decapoda: Palinuridae) from Easter Island using Next Generation Sequencing
Díaz-Cabrera, E., Meerhoff, E., Rojas-Hernandez, N., Vega-Retter, C., & Veliz, D.
The spiny lobster Panulirus pascuensis stands out among the endemic species of Easter Island, due to its cultural and economic importance. A total of 16 microsatellite loci were characterized in 18 individuals, 9 of which were polymorphic. The mean number of alleles per locus was 3.44 (2-6) and the observed heterozygosity ranged from 0.11 to 0.93. None of the loci exhibited significant linkage disequilibrium or departures from HWE. These new microsatellites will be used to obtain information about migration, population structure and genetic diversity of P. pascuensis in order to improve the future sustainable management and conservation plans.
Palabras claves: Panulirus pascuensis, Easter Island, Microsatellite, Genetic marker
Referencia APA: Díaz-Cabrera, E., Meerhoff, E., Rojas-Hernandez, N., Vega-Retter, C., & Veliz, D. (2017). Development and characterization of the first 16 microsatellites loci for Panulirus pascuensis (Decapoda: Palinuridae) from Easter Island using Next Generation Sequencing. Revista de Biología Marina y Oceanografía, 52(2), 395-398.http://dx.doi.org/10.4067/S0718-19572017000200018
Characterizing stream‐aquifer exchanges with self‐potential measurements
Valois, R., Cousquer, Y., Schmutz, M., Pryet, A., Delbart, C., & Dupuy, A.
Characterizing the interactions between streams and aquifers is a major challenge in hydrology. Electrical self‐potential (SP) is sensitive to groundwater flow through the electrokinetic effect, which is proportional to Darcy velocity. SP surveys have been extensively used for the characterization of seepage flow in a variety of contexts. But to our knowledge, a model coupling SP and groundwater flow has never been implemented for the study of stream‐aquifer interactions. To address the issue, we first implemented a two‐dimensional model to a synthetic stream‐aquifer cross section. Results underline the very distinct nature of SP profiles in gaining or losing stream conditions. Second, we presented a field application in a transect crossing a stream in losing conditions. The coupled model successfully reproduced the observed SP profile. This inverse modeling of the SP signal provides quantitative data on hydrodynamic parameters (hydraulic conductivity, hydraulic heads) and geophysical parameters (coupling coefficient). Nevertheless, all relevant parameters cannot be uniquely estimated without precise prior information on at least some of these parameters. Our results confirm the potential of SP surveys on the characterization of stream‐aquifer exchanges. Recommendations on the collection of high‐quality data are also provided, along with a description of the contexts in which the methodology is likely to perform well.
Referencia APA: Valois, R., Cousquer, Y., Schmutz, M., Pryet, A., Delbart, C., & Dupuy, A. (2017). Characterizing stream‐aquifer exchanges with self‐potential measurements. Groundwater, 1-14. http://dx.doi.org/10.1111/gwat.12594
First insight into the heritable variation of the resistance to infection with the bacteria causing the withering syndrome disease in Haliotis rufescens abalone
Brokordt, K., González, R., Farías, W., Winkler, F. E., & Lohrmann, K. B.
Withering syndrome disease has experienced worldwide spread in the last decade. This fatal disease for abalone is produced by a rickettsia-like organism (WS-RLO), the bacterium “Candidatus Xenohaliotis californiensis”. To evaluate the potential of the red abalone (Haliotis rufescens) to improve its resistance to infection by WS-RLO, the additive genetic component in the variation of this trait was estimated. For this, the variation in infection intensity with WS-RLOs and WS-RLOv (phage-infected RLOs) was analyzed in 56 families of full-sibs maintained for three years in a host-parasite cohabitation aquaculture system. A WS-RLO prevalence of 65% was observed in the analysed population; and from the total WS-RLO inclusions 60% were hyperparasited with the phage (WS-RLOv). The decrease in the food ingestion rate was the sole negative effect associated with increasing WS-RLO intensity of infection, suggesting that the high level of WS-RLOv load may have diminished the symptoms of WS disease in the analyzed abalones. The estimated heritabilities were moderate to mid, but significant, varying from 0.21 to 0.23 and 0.36 for WS-RLO and WS-RLOv infections, respectively. This suggests that variation in resistance to infection with WS-RLO may respond to selection in the evaluated red abalone population. Estimated response to selection (G) for the level of infection by WS-RLO indicated that if the 10% of red abalone with the lowest infection level is selected as broodstock, a 90% reduction in the intensity of infection in the progeny can be expected, even with the lowest estimation of heritability (h2 = 0.21). This strong response would be also due to the large phenotypic variance of this trait. Strong positive correlations, both phenotypic and genotypic, were observed between infection intensities with WS-RLO and WS-RLOv, indicating that selection to increase resistance to one of the types of RLOs will affect resistance in the other in the same direction. This is the first study that demonstrates the existence of additive genetic variation for resistance to WS-RLO in abalone. Consequently, it is possible to increase the resistance to WS-RLO in H. rufescens by selective breeding, which can be an economically attractive and environmentally friendly manner to reduce mortalities and growth effects caused by WS in abalone farms.
Palabras claves: Withering syndrome, Heritability, WS-RLO infection, Phage-infected WS-RLOs, Disease resistance, Abalone
Referencia APA: Brokordt, K., González, R., Farías, W., Winkler, F. E., & Lohrmann, K. B. (2017). First insight into the heritable variation of the resistance to infection with the bacteria causing the withering syndrome disease in Haliotis rufescens abalone. Journal of Invertebrate Pathology, 150, 15-20. https://doi.org/10.1016/j.jip.2017.08.014
An unusual kind of diurnal streamflow variation
Cuevas, J. G., Arumí, J. L., Zúñiga-Feest, A., & Little, C.
During hydrological research in a Chilean swamp forest, we noted a pattern of higher streamflows close to midday and lower ones close to midnight, the opposite of an evapotranspiration (Et)-driven cycle. We analyzed this diurnal streamflow signal (DSS), which appeared mid-spring (in the growing season). The end of this DSS coincided with a sustained rain event in autumn, which deeply affected stream and meteorological variables. A survey along the stream revealed that the DSS maximum and minimum values appeared 6 and 4 hours earlier, respectively, at headwaters located in the mountain forests/ plantations than at the control point in the swamp forest. Et in the swamp forest was higher in the morning and in the late afternoon, but this process could not influence the groundwater stage. Trees in the mountain headwaters reached their maximum Ets in the early morning and/or close to midday. Our results suggest that the DSS is a wave that moves from forests high in the mountains towards lowland areas, where Et is decoupled from the DSS. This signal delay seems to convert the link between streamflow and Et in an apparent, but spurious positive relationship. It also highlights the role of landscape heterogeneity in shaping hydrological processes.
Palabras claves: Evapotranspiration; Groundwater; Riparian zones; Streamflow; Swamp forests
Referencia APA: Cuevas, J. G., Arumí, J. L., Zúñiga-Feest, A., & Little, C. (2018). An unusual kind of diurnal streamflow variation. Journal of Hydrology and Hydromechanics, 66(1), 32-42. https://doi.org/10.1515/johh-2017-0041
Late Quaternary environmental dynamics in the Atacama Desert reconstructed from rodent midden pollen records
De Porras, M. E., Maldonado, A., Pol‐Holz, D., Latorre, C., & Betancourt, J. L.
In the past two decades, much has been learned about the late Quaternary climate history of the Atacama Desert with some details still unclear about the seasonality, timing and extent of wet and dry phases. Modern climate studies reveal that, far from exhibiting a unique pattern, seasonal precipitation originates from many sources and mechanisms. For the last 16 ka, we attempt to sort out these complexities in pollen records from four fossil rodent midden series spanning 22°–25°S in northern Chile. Widespread wet conditions prevailed during the late Pleistocene and early Holocene, particularly between 13 and 9 ka, evidenced by <400 m lowering of pollen zones (plant communities) compared to today. Regional differences in the timing and magnitude of this displacement may be related to the prevailing source (tropical/extra‐tropical) or mode (NNW/SE) of tropical precipitation through time. Wet conditions persisted well into the early Holocene, lasting ∼1–1.5 ka longer than previously suggested. The pollen record suggests extreme drying ∼8 ka, possibly associated with a northward shift of the Inter Tropical Convergence Zone, tracking minimum insolation values at subtropical latitudes during the austral summer. The establishment of conditions similar to today happened ∼4 ka. Copyright © 2017 John Wiley & Sons, Ltd.
Palabras claves: Atacama Desert, Late Pleistocene–Holocene, Paleoclimate, Pollen, Rodent middens
Referencia APA: De Porras, M. E., Maldonado, A., Pol‐Holz, D., Latorre, C., & Betancourt, J. L. (2017). Late Quaternary environmental dynamics in the Atacama Desert reconstructed from rodent midden pollen records. Journal of Quaternary Science, 32(6), 665-684. http://dx.doi.org/10.1002/jqs.2980
Temporal stability and mixed-stock analyses of humpback whales (Megaptera novaeangliae) in the nearshore waters of the Western Antarctic Peninsula
Albertson, G. R., Friedlaender, A. S., Steel, D. J., Aguayo-Lobo, A., Bonatto, S. L., Caballero, S., Constantine, R., Cypriano-Souza, A.L., Engel, M.H., Garrigue, C., Flórez-González, R., Johnston, D.W., Nowacek, D.P., Olavarría, C., Poole, M.M., Read, A.J., Robbins, J., Sremba, A.L., & Baker, C.S.
Southern Hemisphere humpback whales breed in tropical waters and migrate to Antarctica to forage. While the breeding grounds are well defined, the population structure on Antarctic feeding grounds is poorly described. The Western Antarctic Peninsula (WAP) is of particular interest, where rapidly changing environmental conditions could alter prey distribution or migration pathways. To examine changes in the population of whales around the WAP, we used mitochondrial DNA (mtDNA) and 15 microsatellite loci. We compared our WAP dataset to a dataset collected 18 years earlier, and identified new haplotypes for the region, but found no significant difference between the datasets. We compared whales from the WAP to breeding populations in Oceania, Colombia, and Brazil. We used an Analysis of Molecular Variance to confirm significant genetic differentiation between the WAP and each breeding ground (overall F ST = 0.035/0.007 mtDNA/microsatellite, p < 0.001) except Colombia. Bayesian mixed-stock analyses showed a large apportionment to Colombia (mtDNA 93.0%; CL 91–99%; microsatellites 86%; CL 72–93%) and a small apportionment to French Polynesia/Samoan Islands (mtDNA 2.9%; CL 0.0–11.5%; microsatellites 8.9%; CL 0–22%), supporting the strong connection between Colombia and the WAP. Assignment tests allocated 81 individuals to Colombia and two to French Polynesia/Samoan Islands. No other breeding grounds had significant apportionments. Direct connectivity of French Polynesia to the WAP was confirmed with the first genotype match of French Polynesia to a feeding area. Continued genetic monitoring will highlight the complex patterns of humpbacks in this rapidly changing climate. Our results serve as a baseline for humpback whale population structure, illustrate mixed-stock analysis as a useful tool for migrating wildlife, and aid in future management considerations for humpbacks.
Palabras claves: Humpback whales, Population structure, Climate change, Mixed-stock analysis, DNA markers, Antarctic Peninsula
Referencia APA: Albertson, G. R., Friedlaender, A. S., Steel, D. J., Aguayo-Lobo, A., Bonatto, S. L., Caballero, S., Constantine, R., Cypriano-Souza, A.L., Engel, M.H., Garrigue, C., Flórez-González, R., Johnston, D.W., Nowacek, D.P., Olavarría, C., Poole, M.M., Read, A.J., Robbins, J., Sremba, A.L., & Baker, C.S. (2017). Temporal stability and mixed-stock analyses of humpback whales (Megaptera novaeangliae) in the nearshore waters of the Western Antarctic Peninsula. Polar Biology, 1-18. http://dx.doi.org/10.1007/s00300-017-2193-1
Molecular characterization and protein localization of the antimicrobial peptide big defensin from the scallop Argopecten purpuratus after Vibrio splendidus challenge
González, R., Brokordt, K., Cárcamo, C. B., de la Peña, T. C., Oyanedel, D., Mercado, L., & Schmitt, P.
Big defensins are antimicrobial peptides (AMPs) that are proposed as important effectors of the immune response in mollusks, chelicerates and chordates. At present, only two members of the big defensin family have been identified in scallop. In the present work, a cDNA sequence encoding a new big defensin homologue was characterized from the scallop Argopecten purpuratus, namely ApBD1. ApBD1 cDNA sequence comprised 585 nucleotides, with an open reading frame of 375 bp and 5'- and 3′-UTRs of 41 and 167 bp, respectively. The deduced protein sequence contains 124 amino acids with a molecular weight of 13.5 kDa, showing characteristic motifs of the big defensin family and presenting 76% identity with the big defensin from the scallop A. irradians. Phylogenetic analysis revealed that ApBD1 is included into the cluster of big defensins from mollusks. Tissue-specific transcript expression analysis by RT-qPCR showed that ApBD1 was present in all tissues tested from non-immune challenged scallops but it was most strongly expressed in the mantle. The transcript levels of ApBD1 were significantly up-regulated in gills at 24 and 48 h post-injection with the heat-attenuated bacteria Vibrio splendidus. Additionally, immunofluorescence analysis using a polyclonal anti-ApBD1 antibody showed that this protein was abundantly located in epithelial linings of gills and mantle; and also in digestive gland showing ApBD1-infiltrating hemocytes from immune challenged scallops. This is the first time that a big defensin is detected and located at the protein level in a mollusk. These results suggest an important role of ApBD1 in the mucosal immune response of A. purpuratus.
Palabras claves: Antimicrobial peptides, Big defensin, Innate immunity, Mucosal immunity, Scallops
Referencia APA: González, R., Brokordt, K., Cárcamo, C. B., de la Peña, T. C., Oyanedel, D., Mercado, L., & Schmitt, P. (2017). Molecular characterization and protein localization of the antimicrobial peptide big defensin from the scallop Argopecten purpuratus after Vibrio splendidus challenge. Fish & Shellfish immunology, 68, 173-179. https://doi.org/10.1016/j.fsi.2017.07.010
Migratory preferences of humpback whales between feeding and breeding grounds in the eastern South Pacific
Acevedo, J., Aguayo‐Lobo, A., Allen, J., Botero‐Acosta, N., Capella, J., Castro, C., Dalla-Rosa, L., Denkinger, J., Félix, F., Flórez-González, L., Garita, F., Guzmán, H.M, Haase, B., Kaufman, G., Llano, M., Olavarría, C., Pacheco, A.S., Plana, J., Rasmussen, K., Scheidat, M., Secchi, E.R., Silva, S., & Stevick, P.T.
Latitudinal preferences within the breeding range have been suggested for Breeding Stock G humpback whales that summer in different feeding areas of the eastern South Pacific. To address this hypothesis, humpback whales photo‐identified from the Antarctic Peninsula and the Fueguian Archipelago (southern Chile) were compared with whales photo‐identified from lower latitudes extending from northern Peru to Costa Rica. This comparison was performed over a time span that includes 18 austral seasons. A total of 238 whales identified from the Antarctic Peninsula and 25 whales from the Fueguian Archipelago were among those photo‐identified at the breeding grounds. Our findings showed that humpback whales from each feeding area were resighted unevenly across the breeding grounds, which suggests a degree of spatial structuring in the migratory pathway. Humpback whales that feed at the Antarctic Peninsula were more likely to migrate to the southern breeding range between northern Peru and Colombia, whereas whales that feed at the Fueguian Archipelago were more likely to be found in the northern range of the breeding ground off Panama. Further photo‐identification efforts and genetic sampling from poorly sampled or unsampled areas are recommended to confirm these reported connectivity patterns.
Palabras claves: Megaptera novaeangliae, Migratory destinations, Breeding Stock G, Photo‐identification, Feeding ground, Antarctic Peninsula, Fueguian Archipelago
Referencia APA: Acevedo, J., Aguayo‐Lobo, A., Allen, J., Botero‐Acosta, N., Capella, J., Castro, C., Dalla-Rosa, L., Denkinger, J., Félix, F., Flórez-González, L., Garita, F., Gúzman, H.M, Haase, B., Kaufman, G., Llano, M., Olavarría, C., Pacheco, A.S., Plana, J., Rasmussen, K., Scheidat, M., Secchi, E.R., Silva, S., & Stevick, P.T. (2017). Migratory preferences of humpback whales between feeding and breeding grounds in the eastern South Pacific. Marine Mammal Science, 33(4), 1035-1052. http://dx.doi.org/10.1111/mms.12423
Assessment of transboundary river basins for potential hydro-political tensions.
De Stefano, L., Petersen-Perlman, J. D., Sproles, E. A., Eynard, J., & Wolf, A. T.
This paper presents a systematic, global assessment of transboundary watersheds that identifies regions more likely to experience hydro-political tensions over the next decade and beyond based upon environmental, political, and economic indicators. The development of new water infrastructure in transboundary basins can strain relationships among fellow riparians as the impacts of new dams and diversions are felt across borders. Formal arrangements governing transboundary river basins, such as international water treaties and river basin organizations, provide a framework for dialogue and negotiation, thus contributing to assuaging potential disputes. Our study examines these two issues in tandem − the stresses inherent in development and the mitigating impact of institutions − and maps the risk of potential hydro-political tensions that exist where basins may be ill-equipped to deal with transboundary disputes triggered by the construction of new dams and diversions. We also consider several factors that could exacerbate those hydropolitical tensions in the near future, including changes in terrestrial water storage, projected changes in water variability, per capita gross national income, domestic and international armed conflicts, and recent history of disputes over transboundary waters. The study points to the vulnerability of several basins in Southeast Asia, South Asia, Central America, the northern part of the South American continent, the southern Balkans as well as in different parts of Africa, where new water infrastructure is being built or planned, but formal transboundary arrangements are absent. Moreover, in some of these regions there is a concomitance of several political, environmental and socioeconomic factors that could exacerbate hydropolitical tensions. This study contributes to the understanding of how the recent proliferation of development accompanied with unfavourable socio-economic and environmental indicators may influence global hydropolitical resilience.
Palabras claves: Transboundary,Treaty, Assessment, Dispute, Cooperation, Conflict
Referencia APA: De Stefano, L., Petersen-Perlman, J. D., Sproles, E. A., Eynard, J., & Wolf, A. T. (2017). Assessment of transboundary river basins for potential hydro-political tensions. Global Environmental Change, 45, 35-46. https://doi.org/10.1016/j.gloenvcha.2017.04.008