Phosphorus (P) is an essential element for life that must be managed sustainably. The institutional framework for P recovery from wastewater includes policies, regulations, plans, and actions that promote the recovery, recycling, and safe use of this element, aimed at moving toward more sustainable nutrient management and environmental protection. This review analyzes the status of the institutional framework for P recovery from wastewater in different countries around the world. Europe is the continent where the most progress has been made in terms of legislation. Countries such as Germany, the Netherlands, Austria, and Denmark have already implemented policies and regulations that promote environmental protection, as well as P recovery and reuse. In other parts of the world, such as the United States, China, and Japan, there have also been significant advances in promoting the closure of the P cycle, with the implementation of advanced recovery technologies in wastewater treatment plants and regional/national action plans. By contrast, in Latin America there has been little progress in P treatment and recovery, with a weak regulatory framework, unclear goals, and insufficient allocation of techno-economic resources. In this context, it is necessary to reinforce the comprehensive institutional framework, which covers technological aspects, economic incentives, political agreements, and regulations, to promote the sustainable management of this valuable resource.

The climate crisis has accelerated the frequency and intensity of droughts in the Mediterranean areas, impacting the hydrology and the ecology of their basins. Maule River is the largest watershed in the Chilean Mediterranean Zone. The growing anthropic and environmental pressure has led to changes in the structure and function of its terrestrial ecosystem. However, little is known about its influence on aquatic ecosystems. The effect of the recent extreme drought on the streamflow and its influence on water quality and the benthic macroinvertebrate community structure were evaluated in the Maule River’s lower section. Beyond temporal and spatial fluctuations, healthy and permanently well-oxygenated waters prevailed in the study area. However, during the megadrought period, evidenced by a significant decrease in both precipitation and river streamflow, a greater salt wedge influence was observed, at least, in the last 7 km of the river. Although with certain asynchrony, a change in the structure of the benthic macroinvertebrate community was observed in the upstream stations. This marinization reveals an increase in the domain of marine taxa associated with the Polychaeta group and a clear decrease in typical freshwater Oligochaeta individuals. This modification in the structure of the benthic community is expected to affect the function of this estuarine system. The results presented here highlight the importance of considering the variability associated with biological components for the management of water resources and related ecosystem services, considering that one of the main problems associated with changes in land use and the pressures caused by the climate crisis is the decrease in the quality and availability of water in this and other Mediterranean basins globally.

Cryptosporidium parvum and Blastocystis hominis are foodborne parasites known for causing diarrhea. They accumulate in mussels grown on contaminated water bodies, due to the discharge of treated sewage from sewage treatment plants (STP). Despite this, some countries like Chile do not include these parasites in the control or monitoring of sewage water. The objective of this research was to evaluate the contamination of C. parvum. and B. hominis from treated sewage (disinfected by chlorination) and Cholga mussels in a touristic rural cove from the bay of Concepción. Cholga mussels from commercial stores and a treated sewage sample were analyzed. Cryptosporidium spp. was identified by Ziehl-Neelsen-Staining (ZNS) and C. parvum by direct-immunofluorescence assay (IFA) from ZNS-positive samples. Blastocystis hominis was identified by PCR using locus SSU rDNA. C. parvum and B. hominis subtype ST3 were found in 40% and 45% of Cholga mussel samples, respectively, and both parasites were identified in the treated sewage. Blastocystis hominis SSU rDNA gene alignment from Cholga mussels and treated sewage showed 89% of similarity, indicating that could be the same parasite in both samples. We describe the first evidence of possible contamination with these parasites from treated sewage to Cholga mussel suggesting an environmental contamination with high human risk. Based on these results, further studies will consider all the rural coves and STP from the bay to prevent possible contamination of these parasites.

In the north of Chile, several projects propose to promote the diversification of national aquaculture with native fish species. However, one of the expected impacts of climate change on the Chilean coasts is an increase in the intensity and frequency of hypoxia events. Therefore, it can become one of the main problems for fish aquaculture in farming facilities. Two species of Chilean diversification programs are Seriola lalandi and Seriolella violacea, which have different habitats and may have different oxygen requirements. Thus, this work aimed to evaluate the variations in oxygen consumption rates in 10 month-old juveniles of both fish species and to determine the presence of tolerant and non-tolerant individuals at low dissolved oxygen (DO) availability. A simulation of an acute hypoxia event by loss-of-equilibrium (LOEhyp) experiments allowed us to classify tolerant and non-tolerant fish. Then, individual oxygen consumption rates were measured, and the resting metabolic rate (RMR) and the maximum metabolic rate (MMR) for hypoxia-tolerant and non-tolerant juveniles were obtained. The results reveal that S. lalandi juveniles have a higher oxygen demand than S. violacea, the first presenting a significantly higher metabolic rate and locomotor activity. Furthermore, the blood parameters suggest that triglyceride metabolism could be used as alternative energy sources by S. violacea during hypoxic-environments. The juveniles classified as tolerant from both species have a lower RMR than non-tolerant fish, which is associated with reduction in their locomotor activity evidenced by decreasing tail beat frequency. Furthermore, the hypoxia-tolerant juveniles also reached a significantly higher size than non-tolerant fish. This work provides valuable results for the future S. lalandi and S. violacea industries, considering the effects of low OD in the farms. Likewise, the first evidence of the hypoxia adaptive mechanism of native fish are presented, providing scientific support for their aquaculture in Chile.

Flavobacterial infection associated with diseased fish is caused by multiple bacterial species within the family Flavobacteriaceae. In the present study, the Chilean isolate FP99, from the gills of a diseased, farmed rainbow trout (Oncorhynchus mykiss), was characterized using phenotypic and genomic analyses. Additionally assessed was pathogenic activity. Phylogenetic analysis based on 16S rRNA gene sequencing confirmed that isolate FP99 belonged to the genus Epilithonimonas, an average nucleotide identity value of 100% was detected with the Chilean isolate identified as Epilithonimonas sp. FP211-J200. In silico genome analysis, mechanisms for toxins production, and superantigens, adhesion, or other genes associated with virulence were not detected. However, genes encoding proteins for antibiotic resistance were found, including the chrA gene and the nucleotide sequence that encodes for multiple antibiotic resistance MarC proteins. Furthermore, the blaESP-1 gene (87.85% aminoacidic sequence identity), encoding an extended-spectrum subclass B3 metallo-β-lactamase and conferring carbapenem-hydrolysing activity, and the tet(X) gene, which encodes a monooxygenase that catalyses the degradation of tetracycline-class antimicrobials were carried by this isolate. Phenotyping analyses also supported assignment as E. ginsengisoli. Challenge trials against healthy rainbow trout resulted in no observed pathogenic effect. Our findings identify for the first time the species E. ginsengisoli as associated with fish farming, suggesting that this isolate may be a component of the microbiota of the freshwater system. Notwithstanding, poor environmental conditions and any stressors associated with aquaculture situations or lesions caused by other pathogenic bacteria, such as F. psychrophilum, could favour the entry of E. ginsengisoli into rainbow trout.

Abstract This study aimed to verify the bactericidal activity of Copaiba oil, Copaifera duckei, against the main tilapia pathogens and the effect on dietary levels of commercial Copaiba oil for 30 days on zootechnical performance, hematological, biochemical, immunological and histological parameters before and after an experimental infection with Streptococcus agalactiae in Nile tilapia. Fish were randomly distributed into 15 fiber tanks in five treatments (0%, 0.25%, 0.50%, 0.75% and 1.0%) and fed with commercial diet supplemented wit Copaiba oil for 30 days. After this period, the fish were randomly redistributed for the experimental challenge with S. agalactiae into six treatments (T0, T1, T2, T3, T4 and T5) and the fish were anesthetized, and blood samples were collected to assess hematological, biochemical, immunological and histological parameters. Copaiba oil showed bactericidal activity against Streptococcus spp. and Flavobacterium spp. in vitro. In addition, concentrations of 0.75% and 1.0% has an anti-inflammatory effect and improve hematological and immunological parameters, increasing the leukocyte numbers, albumin and serum lytic activity. Furthermore, there is an increase in the intestinal villus length and tissue damage in groups at concentrations 0.75% and 1.0% of Copaiba oil. In conclusion, oral supplementation enhanced non-specific immune parameters and digestibility in Nile Tilapia.

Tenacibaculum dicentrarchi is the second most important pathogen in Chilean salmon farming. This microorganism causes severe skin lesions on the body surface of farmed fish. The bacterium can also adhere to surfaces and form biofilm, survive in fish skin mucus, and possess different systems for iron acquisition. However, the virulence mechanisms are still not fully elucidated. Outer membrane vesicles (OMV) are nanostructures released by pathogenic Gram-negative bacteria during growth, but none has been described yet for T. dicentrarchi. In this study, we provide the first reported evidence of the fish pathogen T. dicentrarchi producing and releasing OMV from 24 h after incubation, increasing thereafter until 120 h. Analyses were conducted with T. dicentrarchi TdCh05, QCR29, and the type strain CECT 7612T . The OMV sizes, determined via scanning electron microscopy, ranged from 82.25 nm to 396.88 nm as per the strain and incubation time point (i.e., 24 to 120 h). SDS-PAGE revealed that the number of protein bands evidenced a drastically downward trend among the T. dicentrarchi strains. In turn, the OMV shared five proteins (i.e., 22.2, 31.9, 47.7, 56.3, and 107.1 kDa), but no protein pattern was identical. A heterogeneous amount of protein, RNA, and DNA were obtained, depending on the time at which OMV were extracted. Purified OMV were biologically active and induced a cytotoxic effect in macrophage-enriched cell cultures from rainbow trout (Oncorhynchus mykiss) head kidneys. This is the first step towards understanding the role that OMV could play in the pathogenesis of T. dicentrarchi.

Coastal upwelling is the dominant physical process triggering high biological productivity in Eastern Boundary Upwelling Systems (EBUS). These regions are characterized by intense upwelling events driven by Equatorward alongshore winds. In the Humboldt current system off central-southern Chile (30–40°S) the coastal upwelling process has been studied from several approaches including biogeochemical, fisheries and physical studies. Yet, the phenology of wind-driven upwelling along the meridional gradient has been poorly inspected. Using reanalysis data from the ERA5 product (1966–2020), we calculated the Cumulative Upwelling Index (CUI, m2 s−1 × 1000 m) to characterize the phenology of coastal upwelling off central-southern Chile, identifying the beginning (STI), the maximum (MAX) and the end (END) of the upwelling season. In addition, we quantified the duration (LUSI) and the total magnitude (TUMI) of the upwelling season. The response of the water column to cumulative wind stress was determined using in situ hydrographic data (2002–2020) from a middle shelf station off Concepción, which showed marked seasonal and interannual variability. In general, the onset, duration, and intensity of Ekman transport were highly variable. At 36.5°S (off Concepción), the STI occurred on August 6 ± 25.4 days and the duration of the upwelling season (LUSI) was ∼9 months ± 32.5 days. On the other hand, the TUMI at this latitude was −1.97 × 108± 4.88 × 107. The CUI climatology during El Niño years showed weak and late upwelling (STI = August 29 ± 16.2 days) while upwelling was strong and early (STI = July 13 ± 30.6 days) during La Niña compared to the mean climatology. The water column showed a direct response to cumulative wind-driven upwelling conditions during El Niño 2015-2016 and La Niña 2007-2008. The rise of cold (≤11 °C), saline (34.5 isohaline), dense (>25.8 kg m−3), and oxygen-poor (≤ 1 ml L−1) subsurface waters corresponded to stronger upwelling winds during La Niña 2007–2008. In contrast, coastal upwelling was substantially weak, with a warmer water column and the isotherm of 11.5 °C located below 30 m depth during El Niño 2015–2016.

Strain PVT-9aT, a novel Gram-stain-negative, aerobic, non-spore-forming, motile-by-gliding and rod-shaped bacterium, was isolated from a skin lesion of Atlantic salmon (Salmo salar L.) during a tenacibaculosis outbreak that occurred in 2016 at a Chilean fish farm. Phylogenetic analysis based on 16S rRNA gene sequencing confirmed that strain PVT-9aT belonged to the genus Tenacibaculum, being related to the closest type strains Tenacibaculum haliotis KCTC 52419T (98.49 % sequence similarity), Tenacibaculum aestuariivivum JDTF-79T (97.36 %), Tenacibaculum insulae JDTF-31T (97.29 %) and Tenacibaculum ovolyticum IFO 15947T (97.15 %). The genome size of strain PVT-9aT was 2.73 Mb with a DNA G+C content 31.09 mol%. Average nucleotide identity analysis among 30 Tenacibaculum species rendered the most similar strains as follows: T. haliotis KCTC 52419T (87.91 %), T. ovolyticum IFO 15947T (82.47 %), Tenacibaculum dicentrarchi 35/09T (81.08 %), Tenacibaculum finnmarkense gv finnmarkense TNO006T (80.91 %) and T. finnmarkense gv ulcerans TNO010T (80.96 %). Menaquinone MK-6 was the predominant respiratory quinone. The predominant cell fatty acids (>10 %) were iso-C15 : 0, iso-C15 : 1 G and iso-C15 : 0 3-OH. Phenotypic, chemotaxonomic and genomic data supported the assignment of strain PVT-9aT (=DSM 115155T=RGM 3472T) as representing a novel species of Tenacibaculum, for which the name Tenacibaculum bernardetii sp. nov. is proposed.