RESUMO

Antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) are now considered major global threats. The Kongsfjorden and Krossfjorden are the interlinked fjords in the Arctic that are currently experiencing the effects of climate change and receiving input of pollutants from distant and regional sources. The present study focused on understanding the prevalence of antibiotic resistance of retrievable heterotrophic bacteria from the sediments of adjacent Arctic fjords Kongsfjorden and Krossfjorden. A total of 237 bacterial isolates were tested against 16 different antibiotics. The higher resistance observed towards Extended Spectrum ß-lactam antibiotic (ESBL) includes ceftazidime (45.56%) followed by trimethoprim (27%) and sulphamethizole (24.05%). The extent of resistance was meagre against tetracycline (2.53%) and gentamycin (2.95%). The 16S rRNA sequencing analysis identified that Proteobacteria (56%) were the dominant antibiotic resistant phyla, followed by Firmicutes (35%), Actinobacteria (8%) and Bacteroidetes. The dominant resistant bacterial isolates are Bacillus cereus (10%), followed by Alcaligenes faecalis (6.47%), Cytobacillus firmus (5.75%) Salinibacterium sp. (5%) and Marinobacter antarcticus (5%). Our study reveals the prevalence of antibiotic resistance showed significant differences in both the inner and outer fjords of Kongsfjorden and Krossfjorden (p < 0.05). This may be the input of antibiotic resistance bacteria released into the fjords from the preserved permafrost due to the melting of glaciers, horizontal gene transfer, and human influence in the Arctic region act as a selection pressure for the development and dissemination of more antibiotic resistant bacteria in Arctic fjords.

Assuntos

RESUMO

At the end of summer 2020, a moderate (~105 cells L-1) bloom of potential fish-killing Karenia spp. was detected in samples from a 24 h study focused on Dinophysis spp. in the outer reaches of the Pitipalena-Añihue Marine Protected Area. Previous Karenia events with devastating effects on caged salmon and the wild fauna of Chilean Patagonia had been restricted to offshore waters, eventually reaching the southern coasts of Chiloé Island through the channel connecting the Chiloé Inland Sea to the Pacific Ocean. This event occurred at the onset of the COVID-19 lockdown when monitoring activities were slackened. A few salmon mortalities were related to other fish-killing species (e.g., Margalefidinium polykrikoides). As in the major Karenia event in 1999, the austral summer of 2020 was characterised by negative anomalies in rainfall and river outflow and a severe drought in March. Karenia spp. appeared to have been advected in a warm (14-15 °C) surface layer of estuarine saline water (S > 21). A lack of daily vertical migration patterns and cells dispersed through the whole water column suggested a declining population. Satellite images confirmed the decline, but gave evidence of dynamic multifrontal patterns of temperature and chl a distribution. A conceptual circulation model is proposed to explain the hypothetical retention of the Karenia bloom by a coastally generated eddy coupled with the semidiurnal tides at the mouth of Pitipalena Fjord. Thermal fronts generated by (topographically induced) upwelling around the Tic Toc Seamount are proposed as hot spots for the accumulation of swimming dinoflagellates in summer in the southern Chiloé Inland Sea. The results here provide helpful information on the environmental conditions and water column structure favouring Karenia occurrence. Thermohaline properties in the surface layer in summer can be used to develop a risk index (positive if the EFW layer is thin or absent).

Assuntos

RESUMO

The frosty polar environment houses diverse habitats mostly driven by psychrophilic and psychrotolerant microbes. Along with traditional cultivation methods, next-generation sequencing technologies have become common for exploring microbial communities from various extreme environments. Investigations on glaciers, ice sheets, ponds, lakes, etc. have revealed the existence of numerous microorganisms while details of microbial communities in the Arctic fjords remain incomplete. The current study focuses on understanding the bacterial diversity in two Arctic fjord sediments employing the 16S rRNA gene metabarcoding and its comparison with previous studies from various Arctic habitats. The study revealed that Proteobacteria was the dominant phylum from both the fjord samples followed by Bacteroidetes, Planctomycetes, Firmicutes, Actinobacteria, Cyanobacteria, Chloroflexi and Chlamydiae. A significant proportion of unclassified reads derived from bacteria was also detected. Psychrobacter, Pseudomonas, Acinetobacter, Aeromonas, Photobacterium, Flavobacterium, Gramella and Shewanella were the major genera in both the fjord sediments. The above findings were confirmed by the comparative analysis of fjord metadata with the previously reported (secondary metadata) Arctic samples. This study demonstrated the potential of 16S rRNA gene metabarcoding in resolving bacterial composition and diversity thereby providing new in situ insights into Arctic fjord systems.

Assuntos

RESUMO

Background: In areas of low disturbance, such as the Aysén Region of Chile, the presence of roads can inadvertently facilitate the spread of invasive species. To address this issue, it is imperative to maintain up-to-date biological inventories, as they serve as a primary source of information for the conservation of species and ecosystems. However, the maintenance of systematic inventories of vascular plants in Chile is virtually non-existent, especially outside protected wilderness areas. The data we have come from an inventory of vascular plant species along a stretch of coastal road in Puerto Cisnes (Aysén Region), characterised by a cut slope in the rock. The site is located between mountain ranges, in a region known for its protected wilderness areas and low levels of anthropogenic alteration. The study adopted an observational sampling design, using the road as a transect. For each species identified, the growth substrate, habit and dispersal mode were recorded. A total of 70 species (36 herbs, 23 shrubs and 11 trees) belonging to 42 families were found. The most represented families were Hymenophyllaceae (nine species) and Myrtaceae (four species). We recorded nine introduced species belonging to seven botanical families (Cirsiumvulgare (Savi) Ten., Crocosmiacrocosmiiflora (Lemoine ex Burb. & Dean) N.E.Br., Cytisusscoparius (L.) Link, Digitalispurpurea L., Lotuspedunculatus Cav., Plantagolanceolata L., Polygonumcampanulatum Hook. f., Prunellavulgaris L., Rubusconstrictus Lefèvre & P.J.Müll). Of these nine species, seven are invasive, while the remaining two species have not been assessed for invasive potential (i.e. Crocosmiacrocosmiiflora and Polygonumcampanulatum). In particular, Crocosmiacrocosmiiflora and Rubusconstrictus are new regional records. The majority of species were found growing on the ground (44 species), while a significant proportion were found exclusively on rocky slopes (17 species). According to their seed dispersal mechanism, the most common syndromes were anemochory (32 species) and ornithochory (20 species). Other mechanisms such as mammalochory, ballochory or myrmecochory were less common (less than four species). New information: This study provides valuable data on the vascular flora of Puerto Cisnes, Chile, a modest human settlement in a minimally altered landscape. The region, dominated by native forests and a burgeoning salmon farming industry, has few inventories, so the database presented here adds significantly to local botanical knowledge. The main novelty of this research is that it is the first inventory carried out on a road in a slightly altered area surrounded by protected wilderness areas (such as Magdalena Island National Park and Queulat National Park). The study systematically categorises species according to substrate, habitat and dispersal mode, dimensions that are rarely combined in a single database.The inventory identifies 70 species (36 herbs, 23 shrubs and 11 trees) in 42 families. The most represented families were Hymenophyllaceae (with nine species) and Myrtaceae (with four species). Additionally, we recorded, two introduced species (Crocosmiacrocosmiiflora and Rubusconstrictus) at least 100 km south of their known distribution.

RESUMO

Pinnatoxins (PnTXs) produced by the cosmopolitan dinoflagellate Vulcanodinium rugosum are highly potent cyclic imines that represent a risk for seafood consumers, artisanal fisheries, and the local aquaculture industry. Among the eight known PnTXs, pinnatoxin-G (PnTX-G) is the most frequent toxin analog detected in shellfish. Despite PnTX-G is still not internationally regulated, the French Agency for Food, Environmental and Occupational Health and Safety established that a risk for human consumers may exist when the accumulation of PnTX-G in shellfish exceeds 23 µg kg-1. This study reports the first detection of these fast-acting lipophilic toxins in localized shellfish banks (Mytilus chilensis) from the Chilean coast. Among 32 sentinel sampling stations monthly monitored for phytotoxins detection and quantification between 2021 and 2022 along the southern Chilean coast (from 36°25' S to 54°57'S), PnTx-G was only detected in shellfish from the southernmost region of Magallanes in concentrations that ranged between 15 and 100 µg kg-1, highlighting the binational (Chile/Argentina) Beagle Channel as a 'hotspot'. As Chile is one of the major mussel producers worldwide, this result raises concern about the potential adverse effect of PnTXs for human health and point to the need of governmental actions for an enhanced monitoring of these emerging toxins. To date, the production of PnTXs has not yet been associated with any microalgae species in Chilean waters.

Assuntos

RESUMO

Dinophysis acuminata and D. acuta, which follows it seasonally, are the main producers of lipophilic toxins in temperate coastal waters, including Southern Chile. Strains of the two species differ in their toxin profiles and impacts on shellfish resources. D. acuta is considered the major cause of diarrhetic shellfish poisoning (DSP) outbreaks in Southern Chile, but there is uncertainty about the toxicity of D. acuminata, and little information on microscale oceanographic conditions promoting their blooms. During the austral summer of 2020, intensive sampling was carried out in two northern Patagonian fjords, Puyuhuapi (PUY) and Pitipalena (PIT), sharing D. acuminata dominance and D. acuta near detection levels. Dinophysistoxin 1 (DTX 1) and pectenotoxin 2 (PTX 2) were present in all net tow samples but OA was not detected. Although differing in hydrodynamics and sampling dates, D. acuminata shared behavioural traits in the two fjords: cell maxima (>103 cells L-1) in the interface (S ~ 21) between the estuarine freshwater (EFW)) and saline water (ESW) layers; and phased-cell division (µ = 0.3-0.4 d-1) peaking after dawn, and abundance of ciliate prey. Niche analysis (Outlying Mean Index, OMI) of D. acuta with a high marginality and much lower tolerance than D. acuminata indicated an unfavourable physical environment for D. acuta (bloom failure). Comparison of toxin profiles and Dinophysis niches in three contrasting years in PUY-2020 (D. acuminata bloom), 2018 (exceptional bloom of D. acuta), and 2019 (bloom co-occurrence of the two species)-shed light on the vertical gradients which promote each species. The presence of FW (S < 11) and thermal inversion may be used to provide short-term forecasts of no risk of D. acuta blooms and OA occurrence, but D. acuminata associated with DTX 1 pose a risk of DSP events in North Patagonian fjords.

Assuntos

RESUMO

Harmful algal blooms, in particular recurrent blooms of the dinoflagellate Alexandrium catenella, associated with paralytic shellfish poisoning (PSP), frequently limit commercial shellfish harvests, resulting in serious socio-economic consequences. Although the PSP-inducing species that threaten the most vulnerable commercial species of shellfish are very patchy and spatially heterogeneous in their distribution, the spatial and temporal scales of their effects have largely been ignored in monitoring programs and by researchers. In this study, we examined the spatial and temporal dynamics of PSP toxicity in the clam (Ameghinomya antiqua) in two fishing grounds in southern Chile (Ovalada Island and Low Bay). During the summer of 2009, both were affected by an intense toxic bloom of A. catenella (up to 1.1 × 106 cells L-1). Generalized linear models were used to assess the potential influence of different environmental variables on the field detoxification rates of PSP toxins over a period of 12 months. This was achieved using a four parameter exponential decay model to fit and compare field detoxification rates per sampling site. The results show differences in the spatial variability and temporal dynamics of PSP toxicity, given that greater toxicities (+10-fold) and faster detoxification (20% faster) are observed at the Ovalada Island site, the less oceanic zone, and where higher amounts of clam are annually produced. Our observations support the relevance of considering different spatial and temporal scales to obtain more accurate assessments of PSP accumulation and detoxification dynamics and to improve the efficacy of fisheries management after toxic events.

Assuntos

RESUMO

Dinophysis acuminata and D. acuta, which produce diarrheogenic toxins and pectenotoxins in southern Chile, display site-specific differences in interannual variability (2006 - 2018) in Reloncaví, Pitipalena and Puyuhuapi fjords (41 - 46 °S), Chilean Patagonia. Linear Models show decreasing trends in rainfall and river discharge. Latitudinal decreasing gradients in SST temperature and vertical salinity gradients were observed. A brackish water layer (FW salinity <11 psu), permanently present in Reloncaví, decreased in thickness with time in Pitipalena and was usually absent in Puyuhuapi, the only fjord where D. acuta reached bloom (>103 cells L‒1) densities every season. Dinophysis acuminata, associated with toxin profiles in shellfish that include only pectenotoxins, bloomed everywhere with a poleward increasing gradient. Absence of the FW layer provides a possible index of risk for D. acuta blooms. An apparent poleward shift of D. acuta populations, responsible for DSP outbreaks in Reloncaví in the 1970s, and the recent EU deregulation of pectenotoxins will have a positive impact on the mussel industry in Los Lagos Region. Changes to ongoing monitoring protocols to improve risk assessment capabilities are suggested.

Assuntos

RESUMO

Dinophysis acuta and D. acuminata are associated with lipophilic toxins in Southern Chile. Blooms of the two species coincided during summer 2019 in a highly stratified fjord system (Puyuhuapi, Chilean Patagonia). High vertical resolution measurements of physical parameters were carried out during 48 h sampling to i) explore physiological status (e.g., division rates, toxin content) and ii) illustrate the fine scale distribution of D. acuta and D. acuminata populations with a focus on water column structure and co-occurring plastid-bearing ciliates. The species-specific resources and regulators defining the realized niches (sensu Hutchinson) of the two species were identified. Differences in vertical distribution, daily vertical migration and in situ division rates (with record values, 0.76 d-1, in D. acuta), in response to the environmental conditions and potential prey availability, revealed their niche differences. The Outlying Mean Index (OMI) analysis showed that the realized niche of D. acuta (cell maximum 7 × 103 cells L-1 within the pycnocline) was characterized by sub-surface estuarine waters (salinity 23 - 25), lower values of turbulence and PAR, and a narrow niche breath. In contrast, the realized niche of D. acuminata (cell maximum 6.8 × 103 cells L-1 just above the pycnocline) was characterized by fresher (salinity 17 - 20) outflowing surface waters, with higher turbulence and light intensity and a wider niche breadth. Results from OMI and PERMANOVA analyses of co-occurring microplanktonic ciliates were compatible with the hypothesis of species such as those from genera Pseudotontonia and Strombidium constituting an alternative ciliate prey to Mesodinium. The D. acuta cell maximum was associated with DSP (OA and DTX-1) toxins and pectenotoxins; that of D. acuminata only with pectenotoxins. Results presented here contribute to a better understanding of the environmental drivers of species-specific blooms of Dinophysis and management of their distinct effects in Southern Chile.

Assuntos

RESUMO

Estuarine ecosystems are characterized by a wide physical-chemical variation that in the context of global change scenarios may be exacerbated in the future. The fitness of resident organisms is expected to be influenced by such variation and, hence, its study is a priority. Some of that variation relates to water vertical stratification, which may create "environmental refuges" or distinct layers of water with conditions favoring the fitness of some individuals and species. This study explored the performance of juvenile mussels (M. chilensis) settled in two distinctive water depths (1 m and 4 m) of the Reloncaví fjord (southern Chile) by conducting a reciprocal transplants experiment. Salinity, saturation state and the contents of CO3 in seawater were among the factors that best explained the differences between the two layers. In such environmental conditions, the mussel traits that responded to such variation were growth and calcification rates, with significantly higher values at 4 m deep, whereas the opposite, increased metabolic stress, was higher in mussels raised and transplanted to the surface waters (1 m). Such differences support the notion of an environmental refuge, where species like mussels can find better growth conditions and achieve higher performance levels. These results are relevant considering the importance of M. chilensis as a shellfish resource for aquaculture and a habitat forming species. In addition, these results shed light on the variable responses exhibited by estuarine organisms to small-scale changes in the characteristics of the water column, which in turn will help to better understand the responses of the organisms to the projected scenarios of climate global change.

Assuntos

RESUMO

We investigated the distribution of microplastics in the water column along a large remote estuarine system located between the Northern and Southern Patagonian Ice Fields in Chilean Patagonia, and connected with the Pacific Ocean through the Gulf of Penas. Microplastic particles were found in all samples, with abundances ranging from 0.1 to 7 particles/m3. Polymers identified were principally acrylics, PET, and cellophane. The average abundance of microplastics in surface waters was similar along the whole estuary (0.4 ± 0.3 particles/m3) with acrylics and epoxy resins being more abundant near Caleta Tortel, the only small village in the area. The observed higher abundance of microplastics in the deeper waters towards the Gulf of Penas points to intrusions of subsurface waters transporting plastic particles from the ocean into the channel system. This underlines the potential of ocean currents in transporting plastic pollution into pristine fjords and channels in Chilean Patagonia.

Assuntos

RESUMO

Carbon (δ13C) and nitrogen (δ15N) stable isotope variations in baleen plates of sei whales (Balaenoptera borealis) stranded after a mass mortality event in Chilean Patagonia were investigated to assess potential dietary and migratory patterns. Carbon and nitrogen isotope ratios of seven baleens from six individuals were analyzed. The δ13C values ranged from - 19.1 to - 15.9‰ and the δ15N values from 8.7 to 15.4‰. Variations of up to 2.9‰ for δ13C and 5.3‰ for δ15N were observed within one baleen. Carbon and nitrogen isotope records of each baleen were significantly correlated and showed recurring oscillations confirmed by wavelet analyses. Oscillations slightly differed in periodicity indicating variable baleen growth rates between 10.0 and 16.5 cm/year. Food sources of the whales are discussed in terms of available isotope data for potential prey taxa and potential migratory behavior on the basis of latitudinal isotope gradients of particulate organic matter. Cyclicity could be explained by regular migrations of the sei whales from subtropical calving areas to high-latitude foraging grounds. δ15N records of baleens differed between individuals eventually pointing to diverse feeding and migratory preferences among sei whale individuals.

RESUMO

The presence of fjords, islands and channels originating from glacial erosion and ice cap retreat, makes the Chilean benthic biodiversity difficult to explore and study. Our survey of this region allowed the identification of 29 Demospongiae species in total. Two of them are new to science and here described: Biemna lutea sp. nov., and Hamigera cleistochela sp. nov.. Two species (Clathria (Clathria) microxa and Lissodendoryx (Ectyodoryx) patagonica,) are new for the region and the Chilean fjords. Lissodendoryx (Ectyodoryx) patagonica was found for the second time after the original description by Ridley Dendy, 132 years ago. These results - considering the small number of species identified on the whole - are promising and confirm that the marine biodiversity of Chilean fjords is remarkable but not well known yet.

Assuntos

RESUMO

The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP.

RESUMO

Although the genus Leucothoe has been reported repeatedly in the Magellan Region, the citations in the Channels and Fjords Ecoregion were either unidentified or attributed to the previously considered cosmopolitan Leucothoe spinicarpa. In this work, Leucothoe kawesqari sp. n. is described, which can be distinguished from other species of the genus in the Southern Ocean by having eyes present, epimeral plates with no setae, anterior coxae not acutely produced or excavate, coxa 5 slightly bilobed, accessory flagellum present, mandibular palp article 3 shorter than ½ article 2, pereopods 5-7 basis expanded, ovoid, posterior margin weakly crenulate and telson apex irregularly truncated. The new species was found in hard substrates, both unvegetated and with macroalgae, mainly in kelp forest of Macrocystis pyrifera.

ResumenA pesar de que el género Leucothoe ha sido citado en la región Magallánica en repetidas ocasiones, las citas en la Ecorregión de Canales y Fiordos o bien no han sido identificados o atribuidos a la antes considerada especie cosmopolita Leucothoe spinicarpa. En este trabajo se describe Leucothoe kawesqarisp. n., que se distingue de otras especies del género que se encuentran en el Océano Antártico por presentar ojos, placas epimerales sin setas, coxas anteriores no puntiagudas ni excavadas, coxa 5 ligeramente bilobulada, flagelo accesorio, artículo 3 del palpo mandibular más corto que la mitad del artículo 2, bases de los pereiópodos 2­7 expandidas con el margen ligeramente crenulado y ápice del telson truncado e irregular. La nueva especie fue encontrada en sustratos duros, tanto sin vegetación como con macroalgas, dominadas por bosques de huiros de la especie Macrocystis pyrifera.