Synchronic distribution of the dinoflagellate Protoceratium reticulatum and yessotoxins in a high stratified fjord system: Tidal or light modulation?

Protoceratium reticulatum is the main yessotoxin-producer along the Chilean coast. Thus far, the yessotoxin levels recorded in this region have not posed a serious threat to human health. However, a bloom of P. reticulatum during the austral summer of 2022 caused the first ban of shellfish collection, due to the high toxin levels. A bloom of P. reticulatum during the austral summer of 2020 allowed an evaluation of the fine-scale distribution of the dinoflagellate during a tidal cycle. High-resolution measurements of biophysical properties were carried out in mid-summer (February 18-19) at a fixed sampling station in Puyuhuapi Fjord, Chilean Patagonia, as part of an intensive 24-h biophysical experiment to monitor the circadian distributions of P. reticulatum vegetative cells and yessotoxins. High P. reticulatum cell densities (>20 × 103 cells L-1) were found in association with a warmer (14.5-15 °C) and estuarine (23.5-24.5 g kg-1) sub-surface water layer (6-8 m). P. reticulatum cell numbers and yessotoxins followed a synchronic distribution pattern consistent with the excursions of the pycnocline. Nevertheless, the surface aggregation of the cells was modulated by the light cycle, suggesting daily vertical migration. The yessotoxin content per P. reticulatum cell ranged from 9.4 to 52.2 pg. This study demonstrates both the value of fine-scale resolution measurements of biophysical properties in a highly stratified system and the potential ecosystem impact of P. reticulatum strains producing high levels of yessotoxins.

An Unprecedented Bloom of Oceanic Dinoflagellates (Karenia spp.) Inside a Fjord within a Highly Dynamic Multifrontal Ecosystem in Chilean Patagonia.

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).

Modeling the dynamics of harmful algal bloom events in two bays from the northern Chilean upwelling system.

The bays of Tongoy and Guanaqueros are located in the Humboldt Current system, where Argopecten purpuratus has been the subject of intense aquaculture development. These bays lie in one of the most productive marine ecosystems on Earth and are dominated by permanent coastal upwelling at Lengua de Vaca Point and Choros Point, one of the three upwelling centers on the Chilean coast. Significantly, this productive system experiences a high recurrence of harmful algal bloom (HAB) events. This paper examines 9-year (2010-2018) samples of three toxic microalgal species collected in different monitoring programs and research projects. During this period, nine HAB events were detected in Guanaqueros Bay and 14 in Tongoy Bay. Among these, three HAB events were produced simultaneously in both bays by Pseudo-nitzschia australis, and two events produced simultaneously were detected in one bay by Alexandrium spp. and the other by Dinophysis acuminata. Before El Niño 2015-16, there were more HAB events of longer duration by the three species. Since El Niño, the number and duration of events were reduced and only produced by P. australis. HAB events were simulated with the FVCOM model and a virtual particle tracker model to evaluate the dynamics of bays and their relationship with HAB events. The results showed retention in bays during the relaxation conditions of upwelling and low connectivity between bays, which explains why almost no simultaneous events were recorded.

Continental shelf off northern Chilean Patagonia: A potential risk zone for the onset of Alexandrium catenella toxic bloom?

Harmful Algal Blooms (HAB) pose a severe socio-economic problem worldwide. The dinoflagellate species Alexandrium catenella produces potent neurotoxins called saxitoxins (STXs) and its blooms are associated with the human intoxication named Paralytic Shellfish Poisoning (PSP). Knowing where and how these blooms originate is crucial to predict blooms. Most studies in the Chilean Patagonia, were focused on coastal areas, considering that blooms from the adjacent oceanic region are almost non-existent. Using a combination of field studies and modelling approaches, we first evaluated the role of the continental shelf off northern Chilean Patagonia as a source of A. catenella resting cysts, which may act as inoculum for their toxic coastal blooms. This area is characterized by a seasonal upwelling system with positive Ekman pumping during spring-summer, and by the presence of six major submarine canyons. We found out that these submarine canyons increase the vertical advection of bottom waters, and thus, significantly enhance the process of coastal upwelling. This is a previously unreported factor, among those involved in bloom initiation. This finding put this offshore area at high risk of resuspension of resting cysts of A. catenella. Here, we discuss in detail the physical processes promoting this resuspension.

Biodiversity in Times of COVID-19 and its Relationship with the Socio-Economic and Health Context: A Look from the Digital Media.

The COVID-19 pandemic has caused a pause in people's activities and a socio-economic crisis worldwide due to confinement. This situation is an unprecedented opportunity to understand how these changes may impact biodiversity and its conservation, as well as to study human-nature interaction. Biodiversity plays an essential role in conservation and economic activities, and in countries with greater inequality and low gross domestic product (GDP), biodiversity could have a low priority. Moreover, how biodiversity is prioritized in a society impacts how the citizens view it, and digital news tends to shape biodiversity narratives. The aim of this work was to determine the main trends in biodiversity-related news categories during the COVID-19 pandemic in countries with terrestrial and marine hotspots and relate them to the socioeconomic and public health context of each country. For this, we searched for news on biodiversity and Covid-19 in the first 6 months of the pandemic and related them to GDP, Gini-index, deaths, and infections by Covid-19. Results showed that conservation, public policies, and use of natural resources stood out as the main news categories across countries, with a positive narrative and mostly related to terrestrial rather than marine environments. On the other hand, the socio-economic and public health characteristics of each country had an influence on which aspect of the biodiversity was reflected in the media. For example, countries with greater inequality were associated with tourism news, additionally, countries with low GDP, high cases, and deaths by Covid-19 were associated with news about cultural diversity. In contrast, countries with high GDP and low inequality were associated with news about zoonosis, research and development, public policies, and alien and invasive species.

Ruptura del septum ventricular como complicación de un evento coronario agudo / Ventricular septal rupture complicating acute myocardial infarction

Resumen La ruptura del septum ventricular (RSV) es una complicación mecánica infrecuente del infarto agudo de miocardio (IAM). Los principales factores de riesgo descritos son la edad avanzada, el género femenino, un primer episodio de IAM y la presencia de enfermedad coronaria. Se sospecha de esta patología cuando clínicamente se evidencia un deterioro inexplicable del estado hemodinámico posterior al infarto. Los estudios imagenológicos (ecocardiograma y Doppler color) ayudan a confirmar el diagnóstico de RSV. Respecto al manejo, la corrección quirúrgica continúa siendo el pilar del tratamiento, ya que posee menor mortalidad en comparación con el abordaje médico no quirúrgico. Se presentan dos casos de ruptura del septum ventricular; el primero corresponde a una paciente femenina adulta mayor, con múltiples comorbilidades, quien desarrolló un síndrome coronario agudo tipo infarto agudo de miocardio con elevación del segmento ST a nivel anteroseptal. Se le realizó angioplastia primaria con evidencia de ruptura del septum ventricular, que fue corregida mediante cirugía de forma temprana. Pasadas veinticuatro horas, presentó ruptura de la pared libre del ventrículo izquierdo, hecho que precipitó su deceso. El segundo caso es una paciente femenina adulta mayor, quien presentó síndrome coronario agudo tipo infarto agudo de miocardio sin elevación del ST en cara lateral. Siete días después se documentó la existencia de la ruptura del septum ventricular, la cual fue corregida de manera tardía, en el día octavo, sin complicaciones asociadas.

Abstract Ventricular septal rupture (VSR) is a rare mechanical complication of acute myocardial infarction (AMI). The main risk factors described are advanced age, female gender, a first episode of AMI and presence of coronary disease. There is suspicion for this condition when clinical evidence shows unexplained deterioration of hemodynamic status following infarction. Imaging studies (echocardiogram and colour Doppler) help confirm the diagnosis of ventricular septal rupture. Regarding management, surgical correction continues to be the mainstay of treatment, as it poses lower mortality in comparison to nonsurgical medical approach. Two cases of VSR are presented, the first one is a female adult patient with multiple comorbidities who developed an acute coronary syndrome of a acute myocardial infarction with an anteroseptal ST segment elevation. Primary angioplasty was performed that evidenced ventricular septal rupture, which was surgically corrected at an early stage. After 24 hours, patient showed left ventricular free wall rupture, which precipitated her death. Second case is a female old patient who presented acute acute coronary syndrome of a acute myocardial infarction without lateral ST segment elevation. Seven days later a ventricular septal rupture was documented, which was corrected at a later stage on the eighth day without associated complications.