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Despite the 243,000 species of marine species described by 2022, our knowledge about the biodiversity in the oceans is still incomplete. This may have dreaded and detrimental effect for the conservation of marine ecosystems under the current anthropization of our biota and the fast pacing climate and global change scenario.However, a large number of online repositories cataloging, storing and distributing biodiversity information hosting taxonomic information and species occurrence data have emerged recently. FishBase, the Global Biodiversity Information Facility (GBIF) and the Ocean Biodiversity Information System (OBIS) are part of these publicly available repositories representing a variety of sources that have exploded in number. However, despite the incredible accumulation of biodiversity records, not all the information is really useful, nor does it represent any new knowledge regarding global species richness patterns.In this study we evaluated the spatial and temporal representativeness of the records of marine fishes (order Actinopterygii) available in the GBIF and OBIS global repositories. We provide a methodological framework based on a set of non-parametric estimators to calculate species richness from incidence data, using hexagonal grids as sampling units overlapped on the marine bioregions worldwide.Using standard ecological and spatial analysis tools, we identify regions that are adequately represented in terms of available records and therefore have more reliable data, as well as regions with few records that do not represent current species richness. We overlap these results with the location of marine protected areas and fishing exploitation zones to understand the anthropogenic effect on marine ichthyofauna. We additionally evaluate hypotheses regarding the taxonomic, geographic, and temporal distribution of information biases to deepen our current understanding of public records of species occurrences worldwide.Considering that more than 40 years of information was analyzed, the results showed that on a global scale, the primary data on marine fish available on GBIF and OBIS platforms are still far from being representative and complete. Only 1.14% of the records were useful for our analyses. In addition, we found that the information seems to be biased towards coastal areas, regions close to developed countries and areas where there is a large fishing activity. Finally, the best represented species and families are those with a small body size, which use shallow habitats and have commercial cultural value.

Con el despertar de las economías asiáticas en los ochenta, la política internacional se encolumnó en torno a un polo estratégico de naturaleza económica, trasladando su eje central desde el océano Atlántico al Pacífico. Fruto de la incertidumbre ambiental, la riqueza de las cadenas de recursos vivos del océano Austral y su condición de paso natural entre océanos y continentes, el austro chileno se ha vuelto un núcleo geográfico en el que confluye una nueva centralidad y una nueva atención; una determinada por la multipolaridad, el temor ante la crisis ambiental, la lucha por la hegemonía tecnológica y los riesgos a una explotación indiscriminada de sus recursos. Este escenario, tan frágil como crucial, invita a una reflexión profunda sobre el papel, las responsabilidades y las capacidades que Chile debe impulsar para fortalecer su control político en esta zona. A través de la mirada multidisciplinaria de destacadas y destacados profesionales e investigadores, este libro entrega argumentos políticos, económicos, sociales, jurídicos, científicos e históricos que respaldan la idea de una nueva australidad para Chile, con el fin de robustecer su posición en la zona y consolidar su proyección hacia el continente blanco.

The Valdivia River estuary (VRE) located in south-central Chile is known as one of the largest estuarine ecosystems on the Pacific coast. This research aims to determine the intra-tidal and sub-tidal variability of saline intrusions into the VRE between November 2017 and March 2019 derived from salinity sensors located along the VRE. Complementary hydrographic measurements were conducted during flood and ebb conditions of the spring and neap tides for each of the four seasons of the year along the central axis of the VRE. The results of the salinity time series showed that saline intrusions (values greater than 0.5 Practical Salinity Units) occurred ~20 km from the estuary mouth, when the total flow of the Cruces and Calle-Calle rivers (main tributaries of the estuary) was low, around 280&ndash, 300 m3 s&minus, 1. During the same period, the best co-variability was observed between the saline intrusions and the mixed-semidiurnal tide and the fortnightly and monthly periods of the tide. Regression analyses indicated that salinity intrusion length (L) is best correlated to discharge (D) with a fractional power model L &alpha, D&minus, 1/2.64 (R2 = 0.88). The decreasing discharge trend, found between 2008&ndash, 2019, implies that saline water intrusions would negatively impact the Valdivia&rsquo, s main drinking water intake during the low rainfall season under future climate conditions.

Crabeater seals exhibit extreme dietary specialization, feeding almost exclusively on Antarctic krill. This specialization has inextricably linked habitat use, life history and evolution of this pinniped species to the distribution of its prey. Therefore, the foraging habitat of crabeater seals can be used to infer the distribution of Antarctic krill. Here, we combined seal movements and diving behaviour with environmental variables to build a foraging habitat model for crabeater seals for the rapidly changing western Antarctic Peninsula (WAP). Our projections show that future crabeater seal foraging habitat and, by inference, krill distribution will expand towards offshore waters and the southern WAP in response to changes in circulation, water temperature and sea ice distribution. Antarctic krill biomass is projected to be negatively affected by the environmental changes, which are anticipated to manifest as a decrease in krill densities in coastal waters, with impacts on the land-/ice-based krill predator community, particularly in the northern WAP. Crabeater seals feed predominantly on Antarctic krill. Combining seal tracks and diving behaviour with environmental variables allows the future foraging habitat, and therefore krill distribution, to be predicted, suggesting a shift offshore and south along the western Antarctic Peninsula.

Temperature and salinity measurements obtained from sensors deployed on Weddell seals (Leptonychotes weddellii) between late austral summer and the following spring for 2010–2012 were used to describe the temporal and spatial variability of hydrographic conditions in the western Ross Sea, with particular emphasis on the inner-shelf region off Victoria Land and McMurdo Sound. Potential temperature-salinity diagrams constructed for regions where the seals remained for extended periods showed four water masses on the continental shelf: Modified Circumpolar Deep Water, Antarctic Surface Water, Shelf Water and Modified Shelf Water. Depth-time distributions of potential density and buoyancy frequency showed the erosion of the upper water column stratification associated with the transition from summer to fall/winter conditions. The within-year and interannual variability associated with this transition was related to wind speed. Changes in upper water column density were positively correlated with cross-shelf wind speeds >5.5 m s−1 with a 3–4 day lag. A range of wind speeds was required to erode the density structure because of different levels of stratification in each year. A comparison of wind mixing potential versus stratification (Wedderburn number) showed that synoptic scale wind events during 2012 with speeds of 5.5 and 6.5 m s−1 were needed to erode the summer stratification for Ross Island and Victoria Land regions, respectively. Stronger winds (>8.5 m s−1) were required during 2010 and 2011. The interannual variability in total heat content accumulated during summer (about 20%) was related to the duration of open water, with the largest heat content occurring in 2012, which was characterized by a summer sea ice minimum stronger than other years and relatively higher mCDW influence over the mid and outer-shelf regions. The heat content was lost after mid-April and reached a minimum in winter as a result of deep winter convection. The quantitative analysis of hydrographic variability of the inner-shelf region of the western Ross Sea obtained from the seal-derived measurements provides a baseline for assessing future changes.

Glacier meltdown is a major environmental response to climate change in the West Antarctic Peninsula. Yet, the consequences of this process for local biodiversity are still not well understood. Here, we analyse the diversity and structure of a species-rich marine subtidal macrobenthic community (consumers and primary producers) across two abiotic environmental gradients defined by the distance from a glacier (several km) and depth (between 5 and 20 m depth) in Fildes Bay, King George Island. The analysis of spatially extensive records of seawater turbidity, high-frequency temperature and salinity data, and suction dredge samples of macrobenthic organisms revealed non-linear and functional group-dependent associations between biodiversity, glacier influence, and depth. Turbidity peaked in shallow waters and in the nearby of the glacier. Temperature and salinity, on the other hand, slightly decreased in the proximity of the glacier relative to reference sites. According to the spatial pattern in turbidity, species richness of consumers was lowest in shallow waters and near to the glacier. Also, Shannon's diversity of consumers significantly decreased in the nearby of glacier across depths. Moreover, the spatial variation in community structure of consumers and primary producers depended on both glacier distance and depth. These results suggest that glacier melting can have significant effects on diversity and community structure. Therefore, the accelerated glacier meltdown may have major consequences for the biodiversity in this ecosystem.

Coastal upwelling ecosystems support some of the most productive fisheries of the planet together with a large shellfish aquaculture sector that depends on oceanographic processes to deliver planktonic larvae to replenish and feed the farmed stock. Coastal shellfish aquaculture operations in Chile and Peru have experienced large interannual fluctuations in larval supply over the past decade, yet the drivers of such variability remain unidentified. To this end, we focused on the effects of environmental variability on larval supply of the farmed Peruvian bay scallop Argopecten purpuratus in a bay in northern Chile (Tongoy Bay, 30∘S) that accounts for over 90% of countrywide landings. We examined the hypothesis that the environmental processes governing larval supply were shared with wild benthic invertebrates with planktonic larval development and compared time series of larval abundance for the scallop with larval supply rates to benthic populations of two well-studied wild intertidal species: the Chthamalid barnacle Jhelius cirratus and the purple mussel Perumytilus purpuratus. To this end, we examined the cross-correlation of larval supply to environmental variability using MODIS satellite fields of sea surface temperature (SST) chlorophyll-a concentration (chl-a) and fluorescence line height (nFLH), together with three climate indices relevant for the south east Pacific sector: the Southern Oscillation index (SOI), the Pacific Decadal Oscillation (PDO) and the Antarctic Oscillation Index (AAO). Our results showed that over the five-year study period (2009–2013), patterns of larval supply to the scallop population were related to inter-annual variability in the environmental processes as captured by their Empirical Orthogonal Functions (EOFs), likely through to adult condition before spawning. Surprisingly, larval supply for none of the wild species showed a clear association to the EOFs. In contrast, scallops and wild species showed significant association to lower frequency climate variability as captured by the SOI and the PDO, but not the AAO. Results suggest that larval supply patterns to Tongoy Bay may be modulated by regional patterns of climatic variability, particularly of tropical origin. Thus, changes in coastal oceanography associated with ongoing changes in global climate could have strong and lasting effects on the supply of seedstock for wild and cultivated species across this eastern boundary coastal system and argue for the establishment of long-term ocean observing and early warning systems along the region.

During summer 2017 an anomalous and unprecedented developing of warm water off the coast of Chile was presented, namely Coastal El Nino event. Coincidentally, a high amount of strandings of Portuguese Man-of-War (Physalia physalis) were present at that time. In this work we determine the latitudinal and seasonal distribution of the pleustonic siphonophore P. physalis in the southeastern Pacific, from January 2016 to December 2017. The northernmost and southernmost records for the southeastern Pacific were recorded in this study, from Arica (18 ∘ 26’S; 70 ∘ 18’W) to Quellon (43 ∘ 21’S; 74 ∘ 07’W) in Chile, respectively. During the surveyed period, the greatest strandings of this species were recorded both in the north (23 ∘ S) and south of Chile (36–38 ∘ S) during the austral summer months, coinciding when sea surface is relatively warmer. The number of strandings registered in 2017 was more than 4 times the number of strandings during 2016; this is 17339 colonies in 2017 and 3910 colonies in 2016. The association between the maximum observed strandings and the time of appearance of Coastal El Nino event during summer 2017 are also discussed. Our findings can be used as guidance in the monitoring of P. physalis, in order to prevent encounters and therefore possible accidents with humans in coastal waters and beaches by strandings.

Climate change is rapidly shaping the living environment of the most abundant keystone species of the Antarctic marine food web, Antarctic krill. Projected future changes for the krill habitat include a sustained increase in ocean temperature and changes in sea ice and chlorophyll a. Here we investigate how these factors affect the early life history of krill and identify the regions around Antarctica where the impact will be greatest. Our tool is a temperature-dependent krill growth model forced by data from comprehensive greenhouse warming simulations. We find that by the year 2100 localized regions along the western Weddell Sea, isolated areas of the Indian Antarctic , and the Amundsen/Bellingshausen Sea will support successful spawning habitats for krill. The failure of potentially successful spawning will have a strong impact on the already declining adult populations with consequences for the Antarctic marine food web, having both ecological and commercial ramifications.

Antarctic krill (Euphausia superba) and crystal krill (Euphausia crystallorophias), important components of the Ross Sea food web, differ in their population distribution. The objective of this study was to determine whether these differing distributions result primarily from differences in spawning locations, larval development times, and transport by the Ross Sea circulation. To address this objective, Lagrangian particle tracking experiments were used to simulate the transport of larvae of Antarctic krill and crystal krill. The particle simulations showed that regions providing inputs of Antarctic krill to the Ross Sea were along the outer shelf/slope. Crystal krill transport and retention were along the shallow banks on the outer Ross Sea shelf. Particles initialized in the inner shelf off Victoria Land showed high retention in the region south and along the Terra Nova Bay polynya, with timescales consistent with development times of crystal krill. These results suggest that the cyclonic circulation over the shelf contributes significantly to the dispersion and retention of crystal krill in parts of the inner Ross Sea continental shelf that overlaps with regions with high concentrations of krill-dependent top predators. The westward circulation along the shelf break contributes to the transport and aggregation of Antarctic krill in regions where Circumpolar Deep Water is observed on the outer continental shelf and along the shelf break. The transport pathways and connectivity obtained from this study provide a baseline for assessing the effects of projected changes in the Ross Sea circulation on the distribution of two important krill species.

A one-dimensional, temperature-dependent model was used to simulate the descent–ascent cycle of the embryos and early larval stages of Antarctic krill to determine which regions of the western Antarctic Peninsula (wAP) continental shelf support successful completion of this cycle under present environmental conditions and those projected to occur as a result of climate change. The transport and fate of the embryo and larva under present and modified conditions was investigated with Lagrangian particle tracking simulations. The two modeling studies were implemented using temperature and density (embryo–larva model) and circulation distributions (Lagrangian particle tracking) obtained from a high resolution version of the Regional Ocean Modeling System configured for the wAP shelf region. Additional simulations used temperature and circulation distributions obtained from simulations that were forced with increased wind speed and increased transport of the Antarctic Circumpolar Current (ACC), both projected to possibly occur with climate change in the wAP region. Simulations using present conditions showed that successful completion of the descent–ascent cycle occurred along the outer shelf and on the shelf in regions with bottom depths of 600–700 m. Estimated residence times for the shelf regions that support success of the embryo and larva were 20–30 days. Thus, krill spawned in the mid and inner shelf regions can be retained in these regions through development to the first feeding stage (calyptopis 1). Increased winds and ACC transport resulted in more onshelf transport of Circumpolar Deep Water (CDW), which increased the volume of warm (1–1.5 °C) water at depth. These conditions supported a moderate increase in success of the krill embryo and larva, but only for limited areas of the shelf where hatching depths decreased by 10–30 m (

International audience; The ocean ecosystems around the west Antarctic Peninsula and South Georgia are two of the best described regional ecosystems of the Southern Ocean. They therefore provide a useful basis for developing comparative analyses of ocean ecosystems around the Antarctic. There are clear and expected differences in seasonality and species composition between the two ecosystems, but these mask an underlying similarity in ecosystem structure and function. This similarity results from the two ecosystems being part of a continuum, from more ice covered regions in the south to open water regions in the north. Within this continuum the major factors affecting ecosystem structure and function are the sea ice, the biogeochemical conditions and the connectivity generated by the flow of the Antarctic Circumpolar Current. Antarctic krill are central to the food web in both ecosystems, but the other species of plankton and predators present are different. These different species provide alternative pathways of energy transfer from primary production to the highest trophic levels. The relative dominance of these species can provide indicators of change in ecosystem structure and function. Both ecosystems are changing as a result of physically and biologically driven processes, and the ecological responses being observed are complex and variable across different species and within the two regions. Species in parts of the northern Antarctic Peninsula are being replaced by species that currently dominate farther north in more oceanic areas such as at South Georgia. The similarity of structure and strong connectivity, mean that projections of future change will require generic models of these ecosystems that can encompass changes in structure and function within a connected continuum from ice covered to open water in winter.

The relative contribution of ocean circulation in producing areas where marine mammals and other predators concentrate to produce biological hot spots along the continental shelf of the western Antarctic Peninsula (wAP) was investigated with numerical Lagrangian particle tracking simulations. Circulation distributions used in the Lagrangian simulations were obtained from the Regional Ocean Modeling System (ROMS) configured for the wAP region, with a horizontal resolution of 4 km and a vertical resolution of 24 sigma-layers. To determine release points for the floats, the simulated circulation fields were first analyzed to estimate scales of temporal variability. The temporal decorrelation scales of the simulated surface flow over most of the wAP shelf were 2–3 days. However, decorrelation scales of about 40 days were found for the surface flow in the southern part of Marguerite Bay. Temporal decorrelation scales for the flow below the permanent pycnocline at the depth of Circumpolar Deep Water (CDW) intrusions (below 250 m) were between 40 and 70 days along the northern flank of Marguerite Trough and extending into Marguerite Bay. Near Adelaide Island, Anvers Island and the offshore side of Alexander Island, the velocity decorrelation scales varied between 40 and 60 days. Floats were released in the wAP simulated circulation fields along the outer and mid-shelf at a range of depths in different seasons. The simulated particle trajectories showed preferred sites for across-shelf transport, with Marguerite Trough being a primary pathway for movement of floats into Marguerite Bay, Crystal Sound and the inner shelf region. The three primary biological hot spots, Crystal Sound, Laubeuf Fjord, and off Alexander Island, were sites with the longest particle residence times, being 18–27 days for Alexander Island and Crystal Sound to almost 35 days for Laubeuf Fjord. However, the source regions and circulation processes that provided the input of particles differed for each site. The Lagrangian particle tracking results showed the importance of the circulation in developing localized biological hot spots along the wAP, perhaps by facilitating aggregation of planktonic prey.

The Western Antarctic Peninsula (WAP) is a site of high krill abundance and a likely source region for krill populations found to the north and east of the area. The U.S. GLOBEC Southern Ocean program studied factors that contribute to the overwintering success of krill in the region of Marguerite Bay, WAP. A MOCNESS net system was used to sample the vertical distribution and abundance of zooplankton relative to physical features (hydrography and circulation) during four broad-scale survey cruises in the fall and winter of 2001 and 2002. Four species were found throughout the study area on all four cruises: Euphausia superba, Euphausia crystallorophias, Euphausia triacantha, and Thysanoessa macrura. The species had significantly different horizontal and vertical distributions. Both E. superba and T. macrura were broadly distributed throughout the area, but the central 50% of their vertical distributions were distinct with E. superba most abundant in the upper 100 m in the coldest, freshest water (average temperature and salinity: −1.13 °C; 33.80) and T. macrura occurring between 100 and 250 m (at 0.01 °C; 34.228). E. crystallorophias had a more coastal distribution and was usually found deeper in slightly warmer and saltier water (−0.44 °C; 33.9982) than E. superba and either overlapped or was above T. macrura in depth. E. triacantha was much rarer and sporadically distributed in the study area and was found substantially deeper (center of distribution about 300 m) in the warmest saltiest water (1.40 °C; 34.65) than the other three euphausiid species. Larval distributions for E. superba indicated that at least some proportion of the populations resulted from reproduction and development on the continental shelf, and not solely from offshore reproduction and transport onto the shelf. A neutral particle tracking model was used to gain insight into the relative importance of shelf versus off-shelf origins for the larvae. The results suggest that a combination of offshore and onshore reproduction can account for the observed E. superba larval distributions in the U.S. SO GLOBEC study site.

Several years of sea surface temperature data (1997–2003) for the coast of Antofagasta Bay—a semi-enclosed bay in northern Chile—were analyzed in order to f...

The early life stages of the Antarctic silverfish (Pleuragramma antarctica), an important prey species for higher predators in the Southern Ocean ecosystem, dominate the larval fish assemblages of the Bransfield Strait, one of the most important areas for larval retention off the Antarctic Peninsula. Nevertheless, the spatial location of areas where they were spawned and the timing of larval hatching remain unknown. By linking Lagrangian particle tracking simulations with age data obtained using otolith microincrements from fish caught north of Joinville Island in a pelagic survey, we estimated the distribution of hatch dates and subsequent growth rates of silverfish reaching the Bransfield Strait, and predicted the areas where they were spawned. Larval hatching peaked during the last week of December, and the inner shelf and shelf break, east of the Larsen Ice shelf, were the dominant areas predicted to contribute to larval assemblages in the Bransfield Strait. Over simulated periods of 600–630 days, 35–40% of particles remained within the Bransfield Strait, suggesting an important source of supply to higher predators feeding off the northern Antarctic Peninsula. The daily growth rate at the mean size of 22.3 mm was 0.18 mm, corresponding to a daily change in size of approximately 0.82% standard length (SL), and large variability in growth rate suggested a wide range of environmental conditions experienced during the period of advection from the spawning areas. These results provide spatial predictions that can be tested empirically in future studies, using the simulated trajectories to inform sampling design and spatial coverage.

Off central Chile, around 33.5°S, the freshwater discharge of the River Maipo generates a small- to intermediate-size plume, which moves up to the north driven by the daily sea breeze and with localized effects on a costal zone of about 10–15 km. The influence of this river plume motion on abundance patterns of larval barnacles was studied in a ∼12 km long transect, including 2–3 stations inside the river plume, one station on the visible turbidity front, and two stations outside the plume. Shipboard campaigns were conducted in January (summer), August (winter), and October 2003 (spring). On each occasion, conductivity–temperature–depth casts, bottom track acoustic Doppler current profiler current measurements, size-fractioned chlorophyll concentration, and stratified plankton sampling were conducted. A significantly higher abundance of barnacle nauplii was found at the river plume front than at the plume or outside the plume. Abundance was highest in the upper 10 m of the water column, where most nauplius larvae were found. The river plume appeared as a surface layer of less saline water moving north of the river mouth, with a buoyant frontal structure progressing at speeds of 5 to 20 cm s−1. Although no peak in chlorophyll was observed at the buoyant front, the highest concentration of effective prey size for feeding nauplii (chlorophyl-a

We studied the occurrence of large high frequency temperature fluctuations and their potential association with settlement of intertidal invertebrates during the spring/summer period 1999/2000 at Las Cruces, on the coast of central Chile. Our results showed the existence of internal tidal bores, characterized by sharp drops in water temperature at the surface and near the bottom, and subsequent temperature increases, which occurred with a semidiurnal periodicity. Measured currents support the hypothesis of alternating onshore and offshore movement of warm-water fronts. The frequency of the events varied through the summer and their amplitude seems to be modulated by onshore winds. The strongest events were observed when strong onshore winds occurred in late afternoon hours and the entire water column showed a semidiurnal temperature signal. Highest values of chlorophyll concentration in the intertidal zone and daily settlement of bivalves, gastropods and crustaceans were observed at times when conditions were favorable for occurrence of internal tidal bores. Results suggest that internal tidal bore warm fronts could play an important role in the transport of neustonic larval invertebrates and the delivery of phytoplankton to at least some intertidal sites along the coast of Chile.