Coast Of Central Chile Research Articles

The impact of fishing on a highly vulnerable ecosystem, the case of Juan Fernández Ridge ecosystem.

The Juan Fernández Ridge (JFRE) is a vulnerable marine ecosystem (VME) located off the coast of central Chile formed by the Juan Fernández Archipelago and a group of seamounts. This ecosystem has unique biological and oceanographic features, characterized by: small geographical units, high degree of endemism with a high degree of connectivity within the system. Two fleets have historically operated in this system: a long term coastal artisanal fishery associated with the Islands, focused mainly on lobster, and a mainland based industrial demersal finfish fishery operating on the seamounts which is currently considered overexploited. The management of these fisheries has been based on a classical single-species approach to determine output controls (industrial fleet) and a mixed management system with formal and informal components (artisanal fleet). There has been growing interest in increasing the exploitation of fisheries, and modernization of the fishing fleet already operating in the JFRE. Under this scenario of increased levels of fishing exploitation and the high level of interrelation of species it might be necessary to understand the impact of these fisheries from a holistic perspective based on a ecosystem-based modeling approach. To address these challenges we developed an Atlantis end-to-end model was configured for this ecosystem. The implemented model has a high degree of skill in representing the observed trends and fluctuations of the JFRE. The model shows that the industrial fishing has a localized impact and the artisanal fisheries have a relatively low impact on the ecosystem, mainly via the lobster fishery. The model indicates that the depletion of large sized lobster has leads to an increase in the population of sea urchins. Although this increase is not sufficient, as yet, to cause substantial flow-on effects to other groups, caution is advised in case extra pressure leads the ecosystem towards a regime shift.

Abundance, composition and succession of sessile subtidal assemblages in high wave-energy environments of Central Chile: Temporal and depth variation

Limited knowledge exists about the sessile species found in wave exposed subtidal environments of southeastern Pacific shores, including the temporal patterns of colonization, growth, succession, and the potential problems they pose to human industries, including oceanic aquaculture and renewable wave energy. Filling this information gap is urgent considering the increased interest to exploit these environments. We conducted a 23mo long experimental study on the coast of central Chile to characterize biofouling colonization, rates of accumulation and succession patterns at two different depths and different substrates. Throughout the study, we recorded 62 species, 36 of which were sessile. Biomass accumulation rates were among the highest recorded, with significantly higher and more seasonal rates above than below the thermocline. Slightly but significantly higher biomass was observed in ceramic tiles than acrylic or safety-walk surfaces, but such differences varied with depth and month of the year. In all materials, surface cover reached nearly 100% within about a month of exposure at 5 m deep in spring and summer months, and over 70% at 15 m deep, with lower cover in winter months. The patterns of total biofouling biomass measured in air (weight) were quite different to those measured submerged in seawater, highlighting the importance of species attributes (body density) when assessing risks of biofouling for different human-made structures. The hydrozoan Obelia geniculata was by far the fastest colonizing macro-invertebrate species throughout the year and both depths, covering the entire plate surface in spring-summer months. Community composition shifted in favor of large-bodied, heavier species when surfaces were exposed for more than 6mo. Succession in shallow waters followed a deterministic path from hydrozoans, to the large-bodied barnacle Austromegabalnus psittacus to dominance by the tunicate Pyura chilensis. Final successional stages appear to be the same in deeper waters, but dominance was not achieved before the end of the experiment. Ecological perspectives and simple recommendations to developers and the productive sector are discussed.

16S rRNA Amplicon Sequencing of Seawater Microbiota from Quintero Bay, Chile, Affected by Oil Spills, Shows the Presence of an Oil-Degrading Marine Bacterial Guild Structured by the Bacterial Genera Alcanivorax, Cobetia, Halomonas, and Oleiphilus.

The Quintero Bay, located along the central coast of Chile, has suffered different oil spills during the past 5 years, impacting marine ecosystems. This report describes the microbial community structure of seawater samples obtained from the Quintero Bay through 16S rRNA amplicon sequencing.

Flooding in Central Chile: Implications of Tides and Sea Level Increase in the 21st Century

Coastal floods have become a serious problem on a global scale, increasing in frequency or magnitude due to natural conditions, and exacerbated by socioeconomic factors. This investigation analyzes the role of tides and average sea levels on the development and intensity of flooding in the lower section of the Andalién River, located toward the southern extreme of the coast of central Chile and northeast of Concepción, the country’s second most populous city. Numerical simulation (1D) was used in five modeled scenarios to determine potential flooding areas, demonstrating the influence of tides in flooding processes as far away as 7.3 km from the river mouth, which is reinforced by the fact that 57% of flooding events occur during syzygies. Further, a climate change-induced sea level rise of 60 cm from current levels by the end of the 21st century would produce a 4% increase in flood-prone areas, with 17% of flooding affecting the current built-up area and 83% of floodplains and salt marshes. Efforts must be made to protect or conserve these latter areas in order to increase natural resilience, given the high costs of implementing structural measures to protect future residential areas.

The Influence of River Discharge on Nutrient Export and Phytoplankton Biomass Off the Central Chile Coast (33°–37°S): Seasonal Cycle and Interannual Variability

Using in situ hydro-chemical data and MODIS-SeaWiFS ocean color images as a proxy of river plumes and phytoplankton biomass from 2000 to 2014, this study documents the temporal co-variability of river discharge, plume area, nitrate and phosphate export and phytoplankton biomass in the coastal waters off Central Chile (33o-37oS). Five major rivers (Maipo, Mataquito, Maule, Itata and Biobio) drain into this region with annual mean discharge ranging from 120 to 1000 m3 s-1. River discharge and coastal plume area present a marked seasonal cycle, reaching maximum values during the winter rainy season (June-September). Export of riverine nutrients also peaks in winter, leading to an increase in phytoplankton biomass within the plumes that can be twice larger than the background values in coastal areas away from the river mouths. Wintertime river discharge, plume area and nutrient export are also correlated at interannual time scales. During a recent extended dry period (2010-2014), river discharges, plume areas and nutrient export clearly decreased by about 50% compared to historical values, reducing significantly the size of the chlorophyll pool within plumes off Central Chile during winter. The potential impacts of droughts are discussed in terms of coastal ecology and primary production, a highly relevant issue considering the projections of a dry climate over Central Chile in the future. Systematic evidence of mega-drought effects upon coastal productivity still does not exist, but it remains a priority to further investigate and quantify these impacts.

Urban development versus wetland loss in a coastal Latin American city: Lessons for sustainable land use planning

Urbanization is a primary cause of wetland loss in coastal metropolitan regions. Therefore, it challenges the preservation of biodiversity and the provision of key ecosystem services for urban settlements. These services include leisure and recreation, climate and water regulation, water purification, and especially alleviation of natural hazards. Tsunami flood mitigation is a particularly valuable regulating service provided by these wetlands, as recently evidenced during the 2010 tsunami that hit the central coast of Chile.The Concepción Metropolitan Area (CMA), located on the central coast of Chile, has experienced noticeable wetland loss in recent decades. Our study focused on the Rocuant-Andalién wetland, which has been particularly affected by urbanization. This wetland strongly contributes to flood control, and has provided effective protection against the CMA’s latest tsunamis (1835 and 2010). Based on Strategic Environmental Assessment (SEA), we have quantified urban growth over the wetland, both executed and projected under the Metropolitan Urban Plan of Concepción (MUPC). Recent loss in wetland area by urban growth has been quantified using land use and cover change (LUCC) maps from 2004 to 2014, obtained from the classification of Landsat images. Prospective changes (considering the complete MUPC deployment) have been inferred by combining the MUPC with the 2014 land cover map. In addition, we quantified the observed effect and planned urban growth on the wetland protected area, geoforms and potential flooding based on the area affected by the last Tsunami. Results show that urban areas have increased by 28% between 2004 and 2014, while future increase is expected to reach 238%. In contrast, wetland area has decreased by 10% from 2004 to 2014 and is expected to decrease by up to 32 %. Thus, the MUPC is not contributing to the mitigation of wetland loss nor the preservation of its biodiversity and ecosystem services. Implications for coastal planning are discussed.

Ecosystem health in coastal areas targeted by small-scale artisanal fisheries: Insights on monitoring and assessment

The assessment of the status of marine ecosystems is still a major challenge, because in general we lack well-established ecosystem-based monitoring programs. The coast of central Chile is subjected to moderate but historic fishing pressure by small-scale fisheries. In spite of the increasing evidences of the impact of fishing beyond target species, there is a lack of systematic ecosystem-based assessments. We focused on this problem with the goal of identifying community components, based on a Biological Traits Analysis, that respond to fishing activities to ultimately define ecosystem health. We sampled a set of study sites subjected to benthic invertebrate gathering, and more recently to kelp harvesting. Sites included paired fishery restricted and open access areas where mobile invertebrates and sessile benthos were surveyed. In addition, kelp density and size structure were assessed in two sites subjected to kelp harvesting (also pairing restricted and open access areas). Target species exhibited higher densities in fishery-restricted areas. Fisheries restricted-areas also showed overall higher richness and redundancy of biological traits. Otherwise, we observed high variability in the structure of sessile benthos linked to small-scale heterogeneity of the seabed. The areas subjected to kelp harvesting exhibited variability in mobile invertebrates’ composition between fishing access regimes, whereas no effects could be detected by only considering target species. Current monitoring efforts seem to be well-suited to address target species but fail to inform on ecosystem health in an area with increasing signs of community-wide effects from fishing. Therefore, we recommend future monitoring schemes targeting community components, beyond commercial species’ densities, at different scales.

Avances en el estudio reproductivo de la reineta (Brama australis) en la costa central de Chile

Reproductive traits information about Pacific pomfret ( Brama australis ) is scarce or not have been updated. Through histological analysis, the type of reproduction, maturity length and different gonadal stages development in males and females were studied. Specimens from the central coast of Chile were analysed. The results confirmed that females exhibited an ovary with asynchronous development, which is a characteristic of partial spawners. The adjusted model indicated that females mature, in average at 37.7 cm of fork length. Data suggests that males mature at smaller sizes compared to females. Based on the absence of recent or imminent reproductive activity in this and other studies, the hypothesis that the reproductive process of the species takes place rather off-shore, beyond the fishing zones is discussed.

A new species of Apocathema Emeljanov, 2016 (Hemiptera, Fulgoroidea: Kinnaridae) from coastal central Chile

Apocathema zapallarensis sp. n. is described from a hygrophilous forest in coastal central Chile, being the second species of its genus. It differs from Apocathema lukashevitshae Emeljanov, 2016 by the more basally positioned, shorter, and cranially concave lobes of the styli and unforked apex of the ventral process of the penis.

A new species of Proctoeces and reinstatement of Proctoeces humboldti George-Nascimento and Quiroga 1983 (Digenea: Fellodistomidae) based on molecular and morphological evidence

The most studied digenean of marine organisms in Chile is by far Proctoeces humboldti, a parasite of the intestine of the clingfish Sicyases sanguineus and gonad of the keyhole limpet Fissurella spp. (progenetic metacercariae). The mussel Perumytilus purpuratus has been suggested as the first intermediate host for this digenean. In a study examining the parasites of S. sanguineus from central Chile, we found specimens of Proctoeces showing significant morphological differences with P. humboldti. To assist in the resolution of the taxonomic identification of these specimens, as well sporocysts obtained from the mussel P. purpuratus from central and northern Chile, phylogenetic studies using DNA sequences from the SSU rRNA, as well the LSU rRNA and Cox 1 gene were performed. Results showed that the clingfish S. sanguineus is a host for two species of Proctoeces (P. humboldti and P. syciases n. sp.) along the northern and central Chilean coast, without geographic separation; the mussel P. purpuratus is the first intermediate host for P. syciases n. sp. but not for P. humboldti in central and northern Chile. Fissurellids (Archaeogastropoda) along the Chilean coast harbor only progenetic stages of P. humboldti, but there is no evidence of progenesis for P. syciases. The reinstatement of Proctoeces humboldti is strongly suggested.

El temporal del 8 de agosto de 2015 en las regiones de Valparaiso y Coquimbo, Chile Central

A storm of August 8, 2015 was characterized by the joint occurrence of meteorological and oceanographic conditions that caused the destruction of coastal infrastructure and buildings in several localities of the central coast of Chile. The extreme swell was added to wind gusts coming from the northwest winds, and a historical minimum of atmospheric pressure. The tide of astronomical origin -although not extreme-, made its contribution to the sea level banking on which the waves broke violent on the coastal edge. In order to study the event, records of: a) 64 weather stations distributed in the coastal zone of Valparaiso and Coquimbo regions, b) six tide gauge stations, c) forecast and wave records in deep-waters, and d) a model of deep-water wave propagation towards the most affected sectors of the region, were processed. From the analysis of these variables, the observed damages in the coastal infrastructure are explained.

Parasites of the Southern silvery grebe Podiceps occipitalis (Aves, Podicipedidae) in Chile.

A total of 97 southern silvery grebes (Podiceps occipitalis), which died as the result of an oil spill on the coast of central Chile, were examined for ecto- and endoparasites. Two lice species including Aquanirmus rollandii (Philopteridae) and Pseudomenopon dolium (Menoponidae) were found from 6.2% (6/97) of birds. In 91.7% (89/97) of cases, grebes were infected with some kind of helminths. Three species of gastrointestinal helminths were detected: Eucoleus contortus (Nematoda), Profilicollis bullocki (Acanthocephala), and Confluaria sp. (Cestoda). In addition, Pelecitus fulicaeatrae (Nematoda) was removed from the tibiotarsal-tarsometatarsal articulation in 13.4% (13/97) of the specimens examined. To our knowledge, these are the first records of A. rollandii, E. contortus, and Confluaria sp. as parasites of P. occipitalis. In addition, these findings expand the distributional range of A. rollandii, E. contortus, P. fulicaeatrae, and Confluaria sp. to Chile.

Mountaintops phylogeography: A case study using small mammals from the Andes and the coast of central Chile.

We evaluated if two sigmodontine rodent taxa (Abrothrix olivacea and Phyllotis darwini) from the Andes and Coastal mountaintops of central Chile, experienced distributional shifts due to altitudinal movements of habitat and climate change during and after the Last Glacial Maximum (LGM). We tested the hypothesis that during LGM populations of both species experienced altitudinal shifts from the Andes to the lowlands and the coastal Cordillera, and then range retractions during interglacial towards higher elevations in the Andes. These distributional shifts may have left remnants populations on the mountaintops. We evaluated the occurrence of intraspecific lineages for each species, to construct distribution models at LGM and at present, as extreme climatic conditions for each lineage. Differences in distribution between extreme climatic conditions were interpreted as post-glacial distributional shifts. Abrothrix olivacea displayed a lineage with shared sequences between both mountain systems, whereas a second lineage was restricted to the Andes. A similar scenario of panmictic unit in the past was recovered for A. olivacea in the Andes, along with an additional unit that included localities from the rest of its distribution. For P. darwini, both lineages recovered were distributed in coastal and Andean mountain ranges at present as well, and structuring analyses for this species recovered coastal and Andean localities as panmictic units in the past. Niche modeling depicted differential postglacial expansions in the recovered lineages. Results suggest that historical events such as LGM triggered the descending of populations to Andean refuge areas (one of the A. olivacea’s lineages), to the lowlands, and to the coastal Cordillera. Backward movements of populations after glacial retreats may have left isolates on mountaintops of the coastal Cordillera, suggesting that current species distribution would be the outcome of climate change and habitat reconfiguration after LGM.

Contenido de metales en muestras biológicas de la isla Rocuant, bahía Concepción, Chile

The presence of heavy metals in organisms tissues from the Rocuant Island, Concepcion Bay, is analyzed. The study was carried out on the bivalve Tagelus dombeii (“navajuela”), Mulinia edulis (“taquilla”), the seaweeds Gracilaria chilensis (“pelillo”) and Rhodymenia sp (“rodymenia”) and the fish Stromateus stellatus (“pampanito “). The metals analyzed were Cd, Fe, Hg, Pb and Zn and there were no previous records in the locality. The sampling for benthic organisms was carried out by “hooka” diving, while fish were caught using a fishing nets. In general, metals concentrations are comparable to values reported in the literature for the same species in other areas of central Chilean coast. This suggests they reflect a natural condition and the levels of Cd, Hg and Pb in the bivalve mollusks are under the acceptance levels for products to export. It should be noticed that Pb content in these organisms is under the analytical detection limits in all organisms, as well as Cd in the fish S. stellatus and the seaweeds G. chilensis. The Fe content in Rhodymenia sp. shows the highest absolute value of the whole study.

Finding of the first fossil seep in the emerged coast of Central Chile (33°56’ S). Characterization and implications.

This study presents the main characteristics of the first fossil hydrocarbon seep documented on the emerged coast of Central Chile. The Navidad Paleoseep (NPS) is an outcrop of carbonate and fossil organisms preserved on the beach of the Navidad locality. The carbonate structure is oriented N45° W, perpendicular to the coastline and discordant with sub horizontal Miocene sequences found in the area. This type of authigenic carbonate accumulation, originates on the sea floor as the result of anaerobic oxidation of methane, generated by low temperature fluids released through seaf loor fractures. The NPS consists mainly of calcium carbonate in the form of matrix and crystallized precipitate. Based on textural features, dominant facies of the outcrop were defined as mudstone and ackestone. The associated mineralogy consists of magnesian calcite, predominantly as micrite matrix, minor components of quartz, albite, amphibole, orthoclase, microcline and fragments of volcanic lithics are also identified. The NPS also contains a variety of fossils, such as bivalves, gastropods, tube worms, teredolites, microbialites and others. The occurrence of Lucinoma promaucana in the paleoseep, evidences a temporal and spatial correlation with the Navidad Formation i.e., would ranges from lower to middle Miocene. The δ13C values vary between -41.4‰ in the matrix and -29.5‰ PDB in bivalve shells, representing the typical negative δ13C values seen in hydrocarbon seeps.

Reproductive output of two benthic resources (Fissurella latimarginata and Loxechinus albus) under different management regimes along the coast of central Chile

Normal 0 21 false false false ES-CL JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-ansi-language:ES-CL; mso-fareast-language:ES-CL;} The biological and ecological benefits of fully and partially marine protected areas are well documented. However, the benefits reaching areas beyond the limits of the reserves are still emerging in spite the fact that they are essential for fishing grounds recovery and to gain support for the protection of the ocean among stakeholders. We analyzed the influence of protection on gonadosomatic index, and also body dry weight, of two economically and ecologically important species: the keyhole limpet, Fissurella latimarginata and the red sea urchin, Loxechinus albus , in order to determine the value of protected areas in directly enhancing reproduction, and therefore potential seeding on exploited areas. We compared two levels of protection in central Chile, determined by fisheries management regimes (in turn associated to fishing pressure): a) areas with fishing restrictions (low or none fishing effort; territorial use rights for fisheries and no-take areas) and b) open access areas (high exploitation rates). We also evaluated the independent influence of upwelling on both variables. Our results show for both species that a) body dry weight is not affected by management regime, b) management regime did not show a consistent impact on gonadosomatic index and c) upwelling did not affect the response variables. Our findings help disentangling the main factors determining reproductive patterns under contrasting human impact scenarios, suggesting that the selection of sites for establishing marine protected areas seems to be less relevant than efficient control of fishing effort and minimum legal size to assure natural seeding.

Egg production patterns of two invertebrate species in rocky subtidal areas under different fishing regimes along the coast of central Chile.

Fishing is a major source of human impact, reducing density and size of a wide range of exploited species in comparison to areas exhibiting strong regulations (no-take and partially protected areas, including Territorial Use Rights for Fisheries, TURFs). Since size and density might have important consequences on reproduction, and therefore natural re-seeding, we monitored adult size, density and potential fecundity of the keyhole limpet (Fissurella latimarginata) and the red sea urchin (Loxechinus albus) in areas under two fishing regimes (TURFs and Open Access Areas, OAAs). Analyzing the distribution of suitable habitats, we predict spatial patterns of potential egg production, to identify reproductive hotspots along the central coast of Chile. The current system of TURFs in central Chile showed higher potential egg production of F. latimarginata and of L. albus than expected under a complete OAAs scenario (67 and 52% respectively). Potential egg production showed more than a twofold reduction when the complete TURFs scenario was compared against complete OAAs condition in both species. Individual size and density explained between 60% and 100% of the variability in potential egg production, suggesting the importance of the enhancement of both biological variables in TURFs in Chile. Potential egg production for both species in the northern part of the studied domain was higher due to the combined effect of (a) suitable habitat and (b) concentration of TURFs. Our results suggest that partially protected areas, such as TURFs can significantly enhance the production of propagules that could seed exploited areas.

Una nueva especie de Callyntra (Coleoptera: Tenebrionidae) para la costa de Chile central

Callyntra Solier, 1836 is an endemic genus of Chile and Argentina which contains 22 described species. Based on adult specimens and an egg from the coast of central Chile, C.tortuosa sp. nov. is described. The relationship with other species of Callyntra, morphological variability, sexual dimorphism and conservation status are discussed.

Use of acoustic and stereo camera systems for assessing demersal fish of Robinson Crusoe Island (Juan Fernández Archipelago, off central Chile)

The Juan Fernandez Archipelago, constituted by Robinson Crusoe, Santa Clara and Selkirk Islands, are peaks of a continuous submarine ridge extended in the east-west direction off the coast of central Chile. It supports a rich endemic fish community, which maintains the livelihood of hundreds of fishermen and their families. In recent years there has been a growing interest in assessing the demersal fish species composition, distribution, and abundance in this system. To accomplish this task traditional trawl surveys are inappropriate because of the complexity and fragile nature of the seafloor, therefore we used scientific echosounders combined with a stereo camera system. Two acoustic surveys (2015 and 2016) were conducted using various configurations of transducers and cameras from ROV and tow-bodies. Results indicate a strong association of demersal fish to bottom reefs and species compositions varying with depth. Using ex-situ target strength (TS) estimates combined with species composition and size d...

Exploring the effects of fishing pressure and upwelling intensity over subtidal kelp forest communities in Central Chile

AbstractUnderstanding the processes that drive kelp forest communities is critical for management and conservation of these productive ecosystems. As a way to advance in this direction, we explored the effects of fishing pressure and upwelling intensity over kelp forest communities along the central coast of Chile. We sampled kelp communities in different upwelling conditions associated with contrasting management regimes, namely Territorial User Rights for Fisheries (TURFs) and open‐access (OA) areas. In TURF areas, we found a 2.6‐fold increase in reef fish biomass, higher diversity of all fish trophic groups, mainly dominated by benthic carnivore feeders, and a 1.8‐fold reduction in the number of kelp grazers. On the other hand, upwelling regimes evidence a 1.6‐fold increase in abundance and recruitment of the dominant kelp (Lessonia trabeculata), and also an increase in biomass of planktivorous reef fishes. We found that grazers were capable of reducing kelp condition (measured as canopy foliage index) in OA areas outside the influence of upwelling. Enclosure experiments in the field revealed the effect of grazers on kelps, reducing kelp growth (i.e., blade elongation) and increasing blade tissue loss. Results provide evidence that TURF areas could be important ancillary conservation instruments in kelp forest ecosystems, if key processes of the subtidal community assemblages (e.g., interactions between grazers and reef fish) are maintained. We conclude that human impact interplays with the influence of upwelling in structuring kelp communities.