Publicaciones

Season-dependent effects of ocean warming on the physiological performance of a native and a non-native sea anemone

Suárez, J., Hansen, M., Urtubia, U., Lenz, M., Valdivia, N., & Thiel, M.

The effects of ocean warming on the physiological performance of marine organisms have been widely studied. However, few studies have considered the relevance of seasonal acclimation to elevated temperatures and whether native and non-native species have similar tolerances to warming. We tested the hypotheses that the susceptibility to warming in two species of sea anemones from temperate latitudes is (i) higher in winter than in summer, and (ii) higher in the native than in the non-native species. Seasonal variability in the upper thermal tolerance limit of Anthothoe chilensis (native) and Anemonia alicemartinae (non-native) individuals from the northern-central coast of Chile was assessed in laboratory experiments during the austral winter 2015 and summer 2016. In line with our predictions, seawater warming (up to 16 °C above natural levels) significantly suppressed individual performance proxies such as survival and asexual reproduction (longitudinal fission) in the native species, but not in the non-native species. However, asexual reproduction in the non-native sea anemone was rare across warming treatments, and the native species showed a stronger capacity to detach from the substratum under adverse thermal conditions. Negative effects of warming on survival and fission were evident only in winter, when asexual reproduction is more intense in these taxa. Finally, water temperatures of 30 °C or more were lethal for both native and non-native sea anemones. These results show that the non-native species may have a broader thermal tolerance (in terms of survival) than the native taxonomically related species, but the latter displays behavioral adaptations to avoid adverse conditions of high temperatures. We suggest that knowledge about life history traits related to seasonal variations in water temperature and the invasion status of a species can help to predict its performance in a warming ocean.

Año: 2020

Palabras claves: Ocean warming, Thermal tolerance, Seasonality, Anthothoe chilensis, Anemonia alicemartinae

Assessment of Gene Expression Biomarkers in the Chilean Pencil Catfish, Trichomycterus areolatus, from the Choapa River Basin, Coquimbo Chile

Ali, J.M., Montecinos, A., Schulze, T.T., Allmon, L.G., Kallenbach, A.T., Watson, G.F., Davis, P.H., Snow, D.D., Bertin, A., Gouin, N., Kolok, A.S.

The objective of this study was to describe changes in the gene expression in the Chilean catfish, Trichomycterus areolatus, based on their geographic location within the Choapa River. Genes of choice included those that are biomarkers of exposure to metals, oxidative stress, and endocrine disruption. Male and female T. areolatus were sampled from four sites in Janu-ary 2015 differently impacted by human activities. In males, but not females, hepatic gene expression of heat shock protein (HSP70) and cytochrome P450 1A (CYP1A) were significantly elevated at the site adjacent to the small city of Salamanca, relative to the other sites. In females, hepatic HSP70, the aryl hydrocarbon receptor (AHR), and the estrogen responsive genes, vitellogenin (VTG) and estrogen receptor alpha (ERα), were significantly lower at the site located furthest downstream. A similar downstream pattern of lower expression levels also was found in ovarian tissue for the genes, HSP70 and ERα. Gill gene expression showed a unique pattern in females as levels of metallothionein were elevated at the site furthest downstream. While analytical chemistry of water samples provided limited evidence of agrichemical contamination, the gene expression data are consistent with an exposure to agrichemicals and metals. T. areolatus may be a valuable sentinel organism and its use as a bioindicator species in some rivers within Chile can provide considerable insight, particularly in situations analytical chemistry is limited by environmental constraints.

Año: 2019

Palabras claves:

Using remote sensing to detect whale strandings in remote areas: The case of sei whales mass mortality in Chilean Patagonia

Fretwell, P., Jackson, J., Ulloa Encina, M., Häussermann, V., Perez Alvarez, M., Olavarría, C., & Gutstein, C.

We test the ability of Very High Resolution satellite (VHR) imagery to detect stranded whales using both manual and automated methods. We use the 2015 mass mortality event in the Gulf of Penas locality, central Patagonia, Chile, as an initial case study. This event was the largest known mass mortality of baleen whales, with at least 343 whales, mainly sei whales (Balaenoptera borealis), documented as stranding. However, even with such a large number of whales, due to the remote location of the gulf the strandings went unrecorded for several weeks. Aerial and boat surveys of the area were conducted two to four months after the mortality event. In this study we use 50cm resolution WorldView2 imagery to identify and count strandings from two archival images acquired just after the stranding event and two months before the aerial and ground surveys, and to test manual and automated methods of detecting stranded whales. Our findings show that whales are easily detected manually in the images but due to the heterogeneous colouration of decomposing whales, spectral indices are unsuitable for automatic detection. Our satellite counts suggest that, at the time the satellite images were taken, more whales were stranded than recorded in the aerial survey, possibly due to the non-comprehensive coverage of the aerial survey or movement of the carcases between survey acquisition. With even higher resolution imagery now available, satellite imagery may be a cost effective alternative to aerial surveys for future assessment of the extent of mass whale stranding events, especially in remote and inaccessible areas.

Año: 2019

Palabras claves: Whales, Islands, Image analysis, Boats, Beaches, Remote areas, Geological surveys, Marine mammals

Seasonal variability of the southern tip of the Oxygen Minimum Zone in the eastern South Pacific (30°-38°S): A modeling study.

Pizarro‐Koch, M., Pizarro, O., Dewitte, B., Montes, I., Ramos, M., Paulmier, A., & Garçon, V.

We investigate the seasonal variability of the southern tip (30°–38°S) of the eastern South Pacific oxygen minimum zone (OMZ) based on a high horizontal resolution (1/12°) regional coupled physical‐biogeochemical model simulation. The simulation is validated by available in situ observations and the OMZ seasonal variability is documented. The model OMZ, bounded by the contour of 45 μM, occupies a large volume (4.5x104 km3) during the beginning of austral winter and a minimum (3.5x104 km3) at the end of spring, just 1 and 2 months after the southward transport of the Peru‐Chile Undercurrent (PCUC) is maximum and minimum, respectively. We showed that the PCUC significantly impacts the alongshore advection of dissolved oxygen (DO) modulating the OMZ seasonal variability. However, zonal transport of DO by meridionally alternating zonal jets and mesoscale eddy fluxes play also a major role in the seasonal and spatial variability of the OMZ. Consistently, a DO budget analysis reveals a significant contribution of advection terms to the rate of change of DO and the prominence of mesoscale variability within the seasonal cycle of these terms. Biogeochemical processes and horizontal and vertical mixing, associated with subgrid scale processes, play only a secondary role in the OMZ seasonal cycle. Overall, our study illustrates the interplay of mean and (mesoscale) eddy‐induced transports of DO in shaping the OMZ and its seasonal cycle off Central Chile.

Año: 2019

Palabras claves: Oxygen minimum zone, Eddy fluxes, Peru‐Chile Undercurrent, Oxygen budget, Eastern South Pacific

The rise and demise of plastic shopping bags in Chile – Broad and informal coalition supporting ban as a first step to reduce single-use plastics

Amenábar Cristi, M., Holzapfel, C., Nehls, M., De Veer, D., Gonzalez, C., & Holtmann, G., Honorato-Zimmer, D., Kiessling, T., Leyton Munoz, A., Narvaez Reyes, S., Nunez, P., Sepulveda, J.M., Vásquez, N., Thiel, M.

Single-use plastic bags (SUPBs) were introduced to society as a way to facilitate our daily lives, but due to their low post-use value they are found as litter in many different environments, from urban to rural and remote, natural environments. Given the increasing awareness about environmental litter, many communities have banned SUPBs in the recent past. Here we explore an emerging economy to document the rise and demise of SUPBs in society. Through a review of scientific and grey literature (including governmental documents and media coverage) we reconstruct the timeline of SUPBs in Chile, including the development of the plastic industry and retail business within Chile, the introduction, spread and finally the demise of SUPBs. Focused on the demise phase, we document the creation and succession of municipal ordinances to reduce SUPBs in local commerce, and the development of a national law to regulate the use of SUPBs. In order to document the involvement of the general public during the demise phase, we also examined current behavior and behavioral intentions of people in (i) a local project introducing reusable cloth bags to reduce the use of SUPBs, and (ii) a consumer survey about public perception of SUPBs and their use. Plastic bags were introduced in Chile in the 1970s, then spread with the emergence of supermarkets and retail stores in the 1980s and 1990s, and were widely used in commerce by the turn of the century. During the first decade of the 21st century the first scientific studies reported large amounts of plastic litter and high proportions of single-use plastics in coastal environments, public awareness grew, and numerous initiatives aiming to reduce consumption and littering of plastics developed. The first municipal ban of SUPBs in 2013 was emulated during the following five years by 62 other Chilean municipalities and in 2018 translated into a national law, which was highly approved and supported by the population. We conclude that the ban of SUBPs in Chile was facilitated by a broad concern among the general public, which led to a bottom-up movement culminating in the national government taking stakes in the issue. Finally, we argue that this can only be a first step that must be followed by further actions to abolish single-use products in order to effectively protect the environment and in particular the world's oceans.

Año: 2019

Palabras claves: Marine litter, Willingness to engage, Socio-economic factors, Pro-environmental behavior, Waste management.

Seasonal Variability of the Southern Tip of the Oxygen Minimum Zone in the Eastern South Pacific (30°‐38°S): A Modeling Study

Pizarro‐Koch, M., Pizarro, O., Dewitte, B., Montes, I., Ramos, M., Paulmier, A., & Garçon, V.

We investigate the seasonal variability of the southern tip (30°–38°S) of the eastern South Pacific oxygen minimum zone (OMZ) based on a high horizontal resolution (1/12°) regional coupled physical‐biogeochemical model simulation. The simulation is validated by available in situ observations and the OMZ seasonal variability is documented. The model OMZ, bounded by the contour of 45 μM, occupies a large volume (4.5x104 km3) during the beginning of austral winter and a minimum (3.5x104 km3) at the end of spring, just 1 and 2 months after the southward transport of the Peru‐Chile Undercurrent (PCUC) is maximum and minimum, respectively. We showed that the PCUC significantly impacts the alongshore advection of dissolved oxygen (DO) modulating the OMZ seasonal variability. However, zonal transport of DO by meridionally alternating zonal jets and mesoscale eddy fluxes play also a major role in the seasonal and spatial variability of the OMZ. Consistently, a DO budget analysis reveals a significant contribution of advection terms to the rate of change of DO and the prominence of mesoscale variability within the seasonal cycle of these terms. Biogeochemical processes and horizontal and vertical mixing, associated with subgrid scale processes, play only a secondary role in the OMZ seasonal cycle. Overall, our study illustrates the interplay of mean and (mesoscale) eddy‐induced transports of DO in shaping the OMZ and its seasonal cycle off Central Chile.

Año: 2019

Palabras claves: Oxygen minimum zone, Eddy fluxes, Peru‐Chile Undercurrent, Oxygen budget, Eastern South Pacific

Multiple reproductive modes of Myrcianthes coquimbensis (Myrtaceae), an endangered shrub endemic to the Atacama Desert

García-Guzmán, P., Loayza, A., & Squeo, F.

Many plants can produce seeds via multiple reproductive modes, such as selfing and outcrossing. Having multiple reproductive modes can be advantageous if it assures seed production when outcrossing fails, which is important for species inhabiting environments where pollinators are scarce or variable. However, it can also be disadvantageous due to the fitness costs associated to selfing. Consequently, plants have mechanisms to reduce the incidence of selfing. Here we examined the breeding system of Myrcianthes coquimbensis; this threatened Atacama Desert shrub is the last species to bloom in the community and exhibits low visitation rates per flower because pollinators are less abundant. Our aim was to determine whether this plant can produce fruits by modes other than outcrossing, and whether it possesses floral traits to prevent sexual interference. We conducted experimental flower treatments in two localities to determine whether fruits were produced by outcrossing, selfing, autonomous selfing and agamospermy. We also evaluated stigma receptivity and pollen viability during a flower’s lifespan. M. coquimbensis developed fruits and seeds by all the reproductive modes assessed, including selfing and agamospermy. Flowers presented partial segregation of sexual functions, with the peak of pollen viability occurring before the peak of stigma receptivity. Selfing is unavoidable in M. coquimbensis and likely interferes with outcrossing. Coupled with possible early inbreeding depression, it probably results in a cost for seed production. Our results suggest that this species may be vulnerable in scenarios where pollinators are scarce; however, agamospermy may provide an alternative route of seed production in these scenarios.

Año: 2020

Palabras claves: Breeding system, Agamospermy, Selfing, Mix-Mating, Protandry, Reproductive assurance, Sexual interference.

Antagonistic interplay between pH and food resources affects copepod traits and performance in a year-round upwelling system

Aguilera, V., Vargas, C., & Dam, H.

Linking pH/pCO2 natural variation to phenotypic traits and performance of foundational species provides essential information for assessing and predicting the impact of ocean acidification (OA) on marine ecosystems. Yet, evidence of such linkage for copepods, the most abundant metazoans in the oceans, remains scarce, particularly for naturally corrosive Eastern Boundary Upwelling systems (EBUs). This study assessed the relationship between pH levels and traits (body and egg size) and performance (ingestion rate (IR) and egg reproduction rate (EPR)) of the numerically dominant neritic copepod Acartia tonsa, in a year-round upwelling system of the northern (23° S) Humboldt EBUs. The study revealed decreases in chlorophyll (Chl) ingestion rate, egg production rate and egg size with decreasing pH as well as egg production efficiency, but the opposite for copepod body size. Further, ingestion rate increased hyperbolically with Chl, and saturated at ~1 µg Chl. L−1. Food resources categorized as high (H, >1 µg L−1) and low (L, <1 µg L−1) levels, and pH-values categorized as equivalent to present day (≤400 µatm pCO2, pH > 7.89) and future (>400 µatm pCO2, pH < 7.89) were used to compare our observations to values globally employed to experimentally test copepod sensitivity to OA. A comparison (PERMANOVA) test with Chl/pH (2*2) design showed that partially overlapping OA levels expected for the year 2100 in other ocean regions, low-pH conditions in this system negatively impacted traits and performance associated with copepod fitness. However, interacting antagonistically with pH, food resource (Chl) maintained copepod production in spite of low pH levels. Thus, the deleterious effects of ocean acidification are modulated by resource availability in this system.

Año: 2020

Palabras claves:

Can hydraulic traits help to explain the current distributional limits in two Nothofagus species in the Chilean Andes?

Carrasco-Urra, F., Saldaña, A., Molina-Montenegro, M.A.

The Andes of central Chile is a geographical gradient with a marked variation in its climatic conditions. Along its
slopes, are distributed the evergreen Nothofagus dombeyi and deciduous Nothofagus pumilio species that show
differences in their leaf habits, range extensions, and in their limits of latitudinal distribution. Plant ecology
proposes that unfavorable climatic conditions are limiting factors that determine the tree species distributions
and that the functional hydraulic traits responses allow understanding the mechanisms underlying the current
distribution of them. We hypothesize that both species will have lower mean values of KL and KS in populations
near to distribution limits compared with middle populations due that unfavorable climatic conditions are
predominant in the latitudinal range limits. We quantify in situ the leaf (KL) and xylem (KS) specific hydraulic conductivities in populations of N. dombeyi and N. pumilio near their northern and southern limits of distribution
as well as in a middle population along Chilean Andes. Results showed that both species had lower mean values
in populations near northern and southern limits compared to populations distributed in middle sites. Also, we
found that the hydraulic performance population of N. pumilio distributed in the middle site had higher than
N. dombeyi. We concluded that lower hydraulic conductivity associated with distribution limits for both study
species implies a lower probability of being affected by embolism, independently of their leaf habits, showing a
functional hydraulic convergence to low water availability or cold.

Año: 2019

Palabras claves: embolism, evergreen vs deciduous, hydraulic traits, Nothofagus , species distribution.