ABSTRACT. Oxyrrhis marina has been reported as an active predator in marine ecosystems, leading us to hypothesize that its grazing activity may impact the dynamics of species during red tide (RT) events in the San Jorge Bay (SJB). We conducted a study on developing one of the largest RT events observed in the SJB between June 2018 and May 2019. We isolated and identified the abundant microorganisms present during the bloom using microscopy techniques. Additionally, we evaluated the grazing activity of O. marina as a predator on phytoplankton species previously isolated from the SJB. Controlled laboratory experiments were conducted with O. marina and six different prey species at a concentration of 1×105 cells mL-1 (1:1) under controlled photoperiod, irradiance, and temperature conditions. The results revealed that the most abundant species during the RT event were Prorocentrum triestinum, P. micans, and O. marina. Regarding grazing preference, after 72 h, O. marina exhibited a significantly higher consumption rate of P. triestinum (19 cells mL-1) compared to the less consumed P. micans (8,627 cells mL-1). The observed strong preference of O. marina for P. triestinum suggests its potential role as a key controller of phytoplankton upwelling during RT periods. This study suggests that the diversity of microorganisms during red tide periods in SJB, Antofagasta, would be regulated by physicochemical and biological factors.

ABSTRACT. Using satellite sensor data for studying sea surface temperature (SST) provides advantages over in situ information, such as obtaining data from large areas and remote access regions in short periods. However, differences between the SST values recorded in situ and those by satellite sensors are due to the intrinsic nature of both methods and meteorological factors. The present study aims to search the difference between SST values from in situ and satellite sensor data of 1×1 km resolution (type L4) from the Group of High-Resolution Sea Surface Temperature (GHRSST) for an annual cycle in a socio-ecological critical area known as the Gulf of Ulloa (GU). The linear regression, linear spline regression, and logic models showed an overestimated SST by satellites compared to in situ data, particularly at temperatures below 20°C. The overestimation can be attributed to the oceanic-atmospheric variations, which are consequences of upwelling and the time lag between the data record morning by in situ and night by satellite sensors. This finding may be relevant in decision-making for marine resource management and conservation in the GU. The information may help to seek the sustainability of this social-environmental system.

ABSTRACT The marine phytoplankton community responds to latitudinal, longitudinal (coast to ocean), and vertical environmental gradients, an important subject in Oxygen minimum zones (OMZ). The phytoplankton structure and the effect of environmental gradients along the central Mexican Pacific, an area within an OMZ, were studied, especially the importance of size fractions and taxonomic groups. A combination of various methods and protocols, such as microscopic analysis, flow cytometer, and pigment analysis, were followed in this study. Oceanographic conditions included thermal gradients along the study area and unreported evidence of a weak upwelling in the southern zone (Acapulco). Vertical distribution of chlorophyll a showed subsurface maxima (SCM, 15-45 m depth) in all stations, and deeper chlorophyll-a maxima (DCM, 85-95 m depth) in more oceanic stations. Chain-forming diatoms dominated in the northern zone stations. Prochlorococcus, Synechococcus, and picoeukaryotes abundances ranged between 0.01 to 21.7 cells×104 mL−1, although most samples showed the highest contribution to biomass (47.95 µg C L−1) by picoeukaryotes. Expected tendencies of Prochlorococcus distribution were observed: highest densities coincided with the DCM and divinyl chlorophyll-a distribution at oceanic stations. Fucoxanthin had the highest concentrations, whereas fucoxanthin and zeaxanthin concentrations were higher at SCM depths. We documented the co-dominance of the pico- and microplankton: picoplankton was important at the DCM, related to oligotrophic and more stratified water column, whereas microplankton prevailed in coastal stations, with mixed water column, high nutrient concentrations, and diatoms as the dominant group. Picoeukaryotes abundances were related to the concentration of prasinoxanthin, which suggests an important mamiellophyte component not previously revealed.

ABSTRACT Fresh roes of rock-boring urchin sea Echinometra lucunter lucunter has a high food value, which enhances its fishery and mariculture; however, biochemical composition and development are influenced by environmental conditions. To evaluate protein, lipid, and carbohydrate content, and be able to establish how it varies the storage in the gonads during upwelling (high primary productivity/22-24°C) and stratification (low primary productivity/28-30°C) seasons, adult sea-urchins (> 30 mm) were monthly collected from Lobos Islet (Venezuela). Salinity, temperature, dissolved oxygen, transparency, total seston and chlorophyll a in superficial seawater were averaged. Biometric parameters, sex, reproductive stage, gonadosomatic index (GI), and biomolecule content in the gonads were determined per individual. Gonadal development of E. lucunter lucunter occurs during the upwelling-stratification transition, corresponding with the seawater temperature increase. Biomolecules showed temporal variations associated with gonadal production; a negative relationship existed between the preferential use of carbohydrates and lipids. Maximal gonad production and accumulated carbohydrate and protein were reached during stratification; however, during upwelling synchronized spawns were observed as well as a respective decrease in lipids and carbohydrates. The environmental conditions during stratification stimulate the gonadal development of E. lucunter lucunter, in comparison the coastal upwelling acts as a trigger of synchronized spawning for both sexes. The energy biomolecules are stored in the roes mainly during stratification, using with preference to carbohydrates to metabolic demand.

RESUMEN Las huevas frescas del erizo de mar Echinometra lucunter lucunter presentan un alto valor alimenticio, lo cual potencia su pesquería y maricultura; no obstante, su composición bioquímica y desarrollo están influenciadas por las condiciones ambientales. Para evaluar el contenido de proteínas, carbohidratos y lípidos, y poder establecer cómo varía el almacenamiento en las gónadas durante las temporadas de surgencia (alta productividad primaria/22-24°C) y estratificación (baja productividad primaria/28-30°C), erizos de mar adultos (> 30 mm) fueron recolectados mensualmente en el Islote Lobos (Venezuela). La salinidad, temperatura, oxígeno disuelto, transparencia, seston total y clorofila a en aguas superficiales fueron estimadas. A cada individuo se le determinó su biometría, sexo, estadio reproductivo, índice gonadosomático (IGS) y contenido de biomoléculas en las gónadas. El desarrollo gonadal de E. lucunter lucunter se inicia durante la transición de surgencia a estratificación, coincidiendo con los aumentos en la temperatura del agua. Las biomoléculas mostraron variaciones temporales asociadas con la producción de gónadas; existiendo una relación negativa entre la preferencia de uso de carbohidratos y lípidos. La maduración gonadal máxima y acumulación de carbohidratos y proteínas fueron alcanzadas durante la estratificación; sin embargo, durante la surgencia se observaron desoves sincronizados, así como un descenso en los lípidos y carbohidratos. Las condiciones ambientales durante la estratificación estimulan el desarrollo gonadal de E. lucunter lucunter, en contraste, la surgencia costera actúa como detonante de los desoves de manera sincronizada para ambos sexos. El almacenamiento de biomoléculas energéticas ocurre principalmente durante la estratificación, usando preferiblemente los carbohidratos para suplir la demanda metabólica.

ABSTRACT The semi-permanent coastal upwelling system within the Humboldt Current System (HCS) off northern Chile provides nutrient-rich, oxygen-poor water to the euphotic zone that contributes to high levels of primary production and restricts the vertical distribution of most zooplankton species according to their tolerance to hypoxia within this highly heterogeneous environment. The day/night vertical distributions of two calanoid copepods, Eucalanus inermis and Nannocalanus minor, were studied concerning the presence of oxygen-poor water associated with the Oxygen minimum zone (OMZ) at a coastal and an offshore station off northern Chile (∼20°S), by stratified sampling from the surface to a depth of 600 m. At the coastal station, most of the population of both species remained above the OMZ, whereas at the offshore station, most populations remained at the edge of the OMZ. Both species exhibited reverse diel vertical migration between day and night and were positively correlated with dissolved oxygen and chlorophyll-a, suggesting that both species may prefer oxygenated waters and avoid the OMZ. However, E. inermis and N. minor exhibited distinct behavior, with E. inermis displaying significant variations among stations and strata and N. minor showing differences only among strata, particularly in the upper strata where it was more aggregated. The results helped us understand the behavior and distribution of zooplankton related to OMZ and how they may change as ocean temperature increases worldwide.

As ocean temperatures increase, so does the need for accurate, regular, and widespread temperature data. This is especially important for researchers studying corals, which can be pushed over their bleaching thresholds by small, sustained changes in water temperature. Satellite data products offer longitudinal estimates of sea surface temperature (SST) taken at regular intervals without the ongoing costs and geospatial limits associated with underwater temperature loggers. However, previous work indicates satellite data are sometimes characterized by significant temperature biases, particularly in stratified coastal waters. Here, we compared the foundation sea surface temperature (fSST) estimated from a highly processed, gridded satellite data set (GHRSST MUR L4 Global SST) to in situ temperature (IST) data collected from coral reef habitats in the top 20 m of the water column at 19 sites in Panama. Comparisons between Pacific and Caribbean coasts and between upwelling and non-upwelling seasons provide a robust test of the utility of this product to estimate subsurface temperatures. The mean differences between fSST and IST show that MUR fSST accurately reflects temperatures at shallow (<9 m) depths on the Caribbean coast (mean bias ≤0.55°C ± standard error (SE) 0.01°C) and during the non-upwelling season on the Pacific coast (mean bias ≤0.26°C ± SE 0.03°C). MUR fSST poorly reflects IST during the Pacific upwelling season, especially at sites 12 m and deeper. In such cases, 66% of satellite estimates deviated from ISTs by >1°C. Our findings underscore how highly processed SST data products should be ground-truthed before being used as a substitute for IST, especially in upwelling areas.

Abstract This study aimed to characterize seasonal changes in microphytoplankton composition and abundance on Bahia continental shelf, a region with upwelling events. Semi-annual sampling was conducted during summer and winter from 2017 to 2021 at nine points. Microphytoplankton was sampled using a conical plankton net through horizontal subsurface drags, using a flowmeter coupled to the net, to measure the total volume of filtered water. Temperature and salinity were measured in situ, presenting typical values of tropical waters. In addition, dissolved inorganic nutrient concentration corroborated a tropical marine oligotrophic pattern. A total of 144 taxa were identified in the region, with the phyla Heterokontophyta and Dinoflagellata being the most representative, as is typically recorded in tropical coastal regions. The density ranged from 6.08 × 104 to 3.38 × 108 cells L-1, with higher average values in summer. Although cyanobacteria accounted for only 3.2% of species richness in the region, due to summer blooms of Trichodesmium erythraeum (2018, 2019, and 2021), it was the most abundant group throughout the study. It was observed that upwelling events do not seem to establish favorable conditions for marked seasonal changes in microphytoplankton composition and abundance. Trichodesmium erythraeum blooms are closely related to physiology and ecological capacity of this species. Except for bloom periods, the study area presented a high species richness and diversity throughout the analyzed time series.

Resumen El objetivo del presente estudio fue caracterizar los cambios estacionales en la composición y abundancia del microfitoplancton en la plataforma continental de Bahía, una región con presencia de eventos de surgencia. Se realizaron muestreos semestrales durante los veranos e inviernos de 2017 a 2021 en nueve puntos. El microfitoplancton se muestreó utilizando una red cónica de plancton en arrastres horizontales debajo de la superficie, utilizando un medidor de corriente acoplado a la red, para medir el volumen total de agua filtrada. La temperatura y la salinidad fueron medidas in situ, presentando valores típicos de aguas tropicales. Además, las concentraciones de nutrientes inorgánicos disueltos corroboraron el patrón oligotrófico marino tropical. Se identificaron un total de 144 taxones en la región, siendo los phyla Heterokontophyta y Dinoflagellata los más representativos, como se registra típicamente en las regiones costeras tropicales. La densidad varió de 6,08 × 104 a 3,38 × 108 células L-1, con valores promedio más altos en verano. Aunque las cianobacterias representaron solo el 3,2% de la riqueza de especies en la región, debido a las floraciones de verano de Trichodesmium erythraeum (2018, 2019 y 2021), fue el grupo más abundante a lo largo del estudio. Se observó que los eventos de surgencia no parecen establecer condiciones favorables para cambios estacionales marcados en la composición y abundancia del microfitoplancton. Las floraciones de Trichodesmium erythraeum están estrechamente relacionadas con la fisiología y la capacidad ecológica de esta especie. Con excepción de los períodos de floración, el área de estudio presentó patrones de alta riqueza y diversidad de especies a lo largo de la serie temporal analizada.

Abstract Ecoacoustic indices may become an important tool to monitor marine ecosystems because they take passive and non-invasive measurements over wide spatial and temporal ranges. However, the performance and limitations of marine ecoacoustic indices are yet to be fully understood. This study evaluated the Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Bioacoustic Index (H), and Normalized Difference Sound Index (NDSI) in a marine protected area (MPA) named Resex mar Arraial do Cabo in a coastal upwelling in Rio de Janeiro, Brazil. All considered variables, such as water temperature, wind direction, solar radiation, and vessel traffic were monitored from September to December 2018. Principal component analysis showed that the ACI index was negatively correlated with the number of vessels, whereas the ADI and H indices were correlated with water temperature. After categorizing specific moments, the ACI configured the best index for differentiating specific times of day, whereas the ADI was ideal for distinguishing between moments with and without vessel presence. Thus, the ACI and ADI showed the best performance overall. This study identified the main variables influencing the soundscape of a productive upwelling region and intensely used MPA. Furthermore, this research has laid the foundation for further exploration and the development of a robust, non-invasive tool for monitoring marine environments. noninvasive non invasive ranges However understood ACI, , (ACI) ADI, (ADI) H, (H) NDSI (NDSI MPA (MPA Janeiro Brazil temperature direction radiation 2018 vessels day presence Thus overall Furthermore robust environments (ACI (ADI (H 201 20 2

RESUMO Este estudo apresenta uma avaliação inicial das características hidrográficas na região do Cânion do Rio Japaratuba, este cânion fica na plataforma continental de Sergipe, Brasil. Foi realizado uma campanha oceanográfica, durante a campanha oceanográfica foram realizados dois transectos de alta resolução espacial nos lados norte e sul do cânion, juntamente com um transecto transversal. Os resultados indicam que as características hidrográficas são semelhantes às encontradas na plataforma continental de Pernambuco, com a massa de água dominante sendo a Água Tropical. No entanto, difere por ter apresentado uma influência maior da Água Costeira, resultado da dispersão da pluma do Rio São Francisco e de pequenos Rios que desaguam na porção norte da plataforma continental do estado de Sergipe, em direção sul. A turbidez e a clorofila próximo ao fundo, foram relativamente mais altas na seção sul, o que pode ser uma indicação de que a presença do cânion pode produzir um efeito de ressurgência localizado, desempenhando um papel no soerguimento da água do topo da termoclina permanente, para uma região mais próxima da costa. Japaratuba Sergipe Brasil transversal Pernambuco Tropical entanto Costeira fundo localizado permanente costa

ABSTRACT This study presents an initial assessment of the hydrographic characteristics in the region of the Japaratuba Canyon on the continental shelf of Sergipe, Brazil. An oceanographic campaign was conducted, during which two high spatial resolution transects were made on the north and south sides of the canyon, along with a transverse transect. The results indicate that the hydrographic features are similar to those found on the continental shelf of Pernambuco, with the dominant water mass being Tropical Water. However, it differs in having a much greater influence from Coastal Water, as a result of the dispersion of the São Francisco River plume to the south and from small rivers that discharge into the northern portion of the continental shelf of the state of Sergipe. The near bottom turbidity and chlorophyll were relatively higher in the southern section, what can be an indication that the presence of the canyon can produce a localized upwelling effect, with the canyon playing a role in allowing the approach of water from the top of the nearest permanent thermocline to the coast. Sergipe Brazil conducted transect Pernambuco Water However section effect coast

Abstract Water springs are manifestations of groundwater to the surface, forming and ensuring the supply and sustainability of streams, lakes, rivers, and dams. Therefore, its riparian forest is considered an area of permanent preservation, which aims to protect the water, as well as the spring, from consequences of disordered population growth, added to deficient basic sanitation systems, climate change, agricultural activities, inappropriate land uses, unplanned urbanization, and diffuse sources of pollution. In addition to compromising water quality, many of these factors affect the permanence of water upwelling at the source, compromising the formation and continuity of streams, lakes, and rivers. In this context, the objective of the present research was to carry out a bibliographic review on water springs, approaching adjacent themes to the main axis of the study that are fundamental for a deep understanding of their importance for the maintenance of water resources and ensuring biodiversity in the search for the sustainability of life for present and future generations. This research collaborates with the environmental view and shows that the function of a water sources is broader than its concepts can reveal. surface streams lakes rivers dams Therefore preservation spring growth systems change activities uses urbanization pollution quality source context generations reveal

Abstract Sound speed profiles in the ocean are determined by seawater properties, where horizontal variability of thermal stratification modulates sonar detection distance. This work assesses the impacts of upwelling dynamics on sound speed profile in enclosed coastal areas by means of temperature observations acquired with a low-cost platform in Anjos Cove, Cabo Frio, Brazil. The Integrated Acquisition System for Research in Acoustics (IARA) consists of a customized 10-meter-long chain of smart temperature sensors (±0.1°C accuracy) mounted in an anchored vertical cable and an echo sounder for tide level measurements. From 2021 to 2023 a number of intrusion events of the cold South Atlantic Central Water (SACW) took place along the Cabo Frio continental shelf, some of which were recorded in the inner region of the Anjos Cove by IARA. Sound speed profiles computed by applying TEOS-10 standards indicate that the sound propagation within Anjos Cove varies often, i.e., several orders of magnitude, under the influence of SACW intrusion events. The phenomenon reflects information from deeper waters on a coastal scale, even at small depths. properties distance lowcost low cost Brazil IARA (IARA 10meterlong meterlong 10 meter long ±0.1°C 01C C 0 1 accuracy measurements 202 (SACW shelf TEOS10 TEOS TEOS-1 often ie i e i.e. magnitude scale depths 20 TEOS1 TEOS- i.e 2

Resumo Ressurgências são importantes processos oceanográficos que induzem diversas mudanças nos ecossistemas marinhos, inclusive no acoplamento bento-pelágico (ABP) que desempenha um papel importante nas áreas costeiras. No entanto, existem poucas informações sobre os possíveis efeitos das ressurgências costeiras no papel trófico de predadores e no ABP. Em vista disso, aqui investigamos as possíveis mudanças sazonais e ontogenéticas nas interações tróficas de um predador demersal, o tira-vira Percophis brasiliensis, em um ecossistema com ressurgência. A amostragem foi realizada ao longo de um ano durante dois eventos de ressurgências costeiras. Baseado nas análises de conteúdos estomacais (ACE) foram registradas mudanças sazonais na dieta provavelmente impulsionadas pelas ressurgências costeiras, levando a um aumento de presas pelágicas e alterando as vias de acoplamento trófico. As análises de isótopos estáveis revelaram que o nicho isotópico diminuiu com o tamanho do corpo, assim como os valores do índice de Levin. Além disso, relações significativas e positivas foram observadas entre δ13C e δ15N versus comprimento total. Nossos resultados mostraram que o predador demersal tem um papel trófico relevante no ABP que provavelmente é influenciado por ressurgências costeiras. marinhos bentopelágico bento pelágico (ABP entanto disso tiravira tira vira brasiliensis ressurgência ACE (ACE corpo Levin δC δ C δN N total

Abstract Upwellings are important oceanographic processes that induce several changes in marine ecosystems, including in the benthic-pelagic coupling (BPC) that plays a major role in coastal areas. However, there is little available information about the possible effects of coastal upwellings on the trophic role of predators and in the BPC. Thus, here we investigate possible seasonal and ontogenetic changes in the trophic interaction of a demersal predator, the Brazilian flathead Percophis brasiliensis, from an upwelling ecosystem. Sampling was carried out for one year during two coastal upwelling events. Based on stomach content analysis (SCA) were recorded seasonal diet shifts, probably driven by coastal upwellings, leading to an increase in pelagic prey and changing the trophic coupling pathways. Stable isotope analysis revealed that isotopic niche decreased with the body size, as well as the values of the Levins’ index. Also, significant, and positive relationships were observed between δ13C and δ15N versus total length. Our results showed that the demersal predator has a relevant trophic role in the BPC which is probably influenced by coastal upwellings. ecosystems benthicpelagic benthic (BPC areas However Thus brasiliensis ecosystem events SCA (SCA shifts pathways size Levins index Also significant δC δ C δN N length

ABSTRACT Functional traits, short life cycles, and the pivotal role in the ocean make copepod diversity a solid foundation for assessing the effect of global changes in marine food webs and ecosystem functioning. Climate change and extreme events, particularly El Niño, can affect coastal ecosystems. The Arvoredo Marine Biological Reserve (MPA), located in highly productive coastal waters of the Southern Brazilian Bight, presents complex climate and oceanographic conditions. This study investigates the influence of oceanographic processes and El Niño 2015-2016 on the copepod functional diversity from 2014 to 2016 in the Arvoredo MPA. Horizontal tows were performed using a WP2 net with a mesh size of 200 µm. The 41 species accounted for 19 functional entities and four functional groups. Our findings reveal that the seasonal intrusion of water masses influenced copepod functional diversity. During summer, the upwelling of South Atlantic Central Water increased nutrient availability and favored large herbivore-omnivores and carnivores. The Plata Plume Water enrichment during winter coincided with a decline in functional richness and abundance, leading to the predominance of the Oithona nana, a small-sized omnivore. Compensatory mechanisms were observed as functional equivalence and species composition shifts. Acartia lilljeborgii and Temora turbinata exhibited functional equivalence and compensated for each other in response to salinity changes associated with upwelling and El Niño. The copepod assemblage demonstrated the ability to maintain functional diversity despite changes in copepod abundance. However, the decline in functional diversity and abundance during the intense winter indicated potential disruption in trophic dynamics and ecosystem functioning. Maintaining balance and compensating for disturbances such as El Niño is crucial for marine food web resilience. The functional trait approach provided a comprehensive understanding of the copepod assemblage in Arvoredo MPA, contributing to a broader knowledge of the impact of oceanographic processes intensification. Monitoring functional diversity and abundance is crucial for evaluating the effects of copepod assemblage changes in ecosystem functionings. traits cycles functioning events ecosystems MPA , (MPA) Bight conditions 20152016 2015 2015-201 201 WP 20 µm 4 1 groups summer herbivoreomnivores herbivore omnivores carnivores nana smallsized small sized omnivore shifts However resilience intensification functionings (MPA 2015201 2015-20 2 201520 2015-2 20152 2015-

Resumen. Los efectos de la temperatura, la irradiancia y otras variables ambientales sobre la fotosíntesis en los pastos marinos son bien conocidos. Sin embargo, existe poca información sobre los efectos del nitrato en el agua marina sobre las características fotosintéticas de los macrófitos marinos. En este estudio, se planteó determinar el efecto de la concentración de nitrato en el agua marina sobre el rendimiento cuántico efectivo del pasto marino Cymodocea nodosa. Los haces de C. nodosa se incubaron con diferentes concentraciones de nitrato y bajo diferentes niveles de irradiancia. En contraste, hubo una disminución de la transmitancia y un aumento exponencial de la absortancia de los haces en función del aumento de los niveles de nitrato. Además, el rendimiento cuántico efectivo del fotosistema II (ΦFSII) en los haces de C. nodosa aumentó exponencialmente al aumentar la concentración de nitrato en el medio. Los valores de ΦFSII en los haces disminuyeron a medida que aumentaba la irradiancia y alcanzaron valores mínimos al mediodía solar o 2 h después. Esta disminución en los valores de ΦFSII, sin embargo, fue 4 veces mayor en los haces incubados bajo radiación solar completa (100% de Eo) en comparación con los incubados con 20% de Eo. Los valores de ΦFSII disminuyeron a casi cero en los haces pre-incubados con 0 µM de NO3 -, mientras que los valores de ΦFSII en los haces pre-incubados con 25 y 100 µM de NO3 - disminuyeron aproximadamente un 25% de sus valores iniciales. Estos resultados indican que los niveles de nitrógeno en el agua marina regulan los valores del rendimiento cuántico efectivo de C. nodosa, lo que sugiere que las características fotosintéticas de este pasto marino podrían estar reguladas por los niveles fluctuantes de nitrato en la columna de agua como aquellos observados en las regiones de surgencia.

Abstract. The effects of temperature, irradiance, and other environmental variables on photosynthesis in seagrasses are well understood. However, little information is available regarding the effects of the nitrate concentration in seawater on the photosynthetic characteristics of marine vegetation. Thus, the aim of this study was to determine the effect of the nitrate concentration in seawater on the effective quantum yield of the seagrass Cymodocea nodosa. Cymodocea nodosa shoots were incubated under different irradiance levels and with different nitrate concentrations. In contrast, a decrease in transmittance and an exponential increase in the absorptance of the shoots were observed as a function of increasing nitrate levels. Furthermore, the effective quantum yield of photosystem II (ΦPSII) in C. nodosa shoots increased exponentially as the nitrate concentration in the media increased. The ΦPSII values in the shoots decreased as irradiance increased and reached minimum values at solar noon or 2 h afterward. However, the decrease of ΦPSII values was 4-fold greater in shoots incubated under full solar radiation (100% natural incident irradiance, Eo) compared to those of shoots incubated with 20% Eo. The ΦPSII values decreased to almost zero in shoots pre-incubated with no nitrate (0 µM NO3 -), whereas ΦPSII values in shoots pre incubated with 25 and 100 µM NO3 - decreased by approximately 25% of their initial values. Collectively, these results indicate that nitrogen levels in seawater regulate the effective quantum yield values of C. nodosa, which suggests that the photosynthetic characteristics of this seagrass might be regulated by fluctuating nitrate levels in the water column such as those that are observed in upwelling regions.

Abstract: External auditory exostosis, an abnormal growth of the tympanic bone caused by exposure to cold water and wind, has been reported in pre-Hispanic individuals buried near the Gulf of Panama, where seasonal coastal upwelling creates ideal conditions for their development, even in a tropical climate. In this study, temporal bones from 135 human skeletons excavated from the archaeological site of Cerro Juan Díaz, Panama (AD 50-1500) were analyzed macroscopically to quantify the prevalence of the lesion and identify possible changes in its frequency during specific cultural periods in this village. A high prevalence of external auditory exostoses was found in mostly male individuals from the Early period (before AD 800), whereas no lesions were found in individuals from the Late period (after AD 800). This sharp decline coincides chronologically with the reduction in carved seashell ornaments found in coastal archaeological contexts around the Gulf of Panama, suggesting that diving declined considerably over time, possibly due to a reduced demand for seashells at the local and regional level.

Resumen: La exostosis del oído externo, un crecimiento anormal del hueso timpánico ocasionada por la exposición del órgano al agua y vientos con baja temperatura, ha sido reportada en individuos prehispánicos enterrados cerca del Golfo de Panamá, donde el afloramiento costero estacional crea las condiciones ideales para su desarrollo, aun en un clima tropical. En este estudio, se analizaron macroscópicamente huesos temporales de 135 esqueletos humanos excavados en el yacimiento de Cerro Juan Díaz, Panamá (50- 1500 DC), para cuantificar la prevalencia de la lesión e identificar posibles cambios en su frecuencia durante periodos culturales específicos en esta aldea. Se encontró una alta prevalencia de la exostosis auditiva externa en individuos mayormente masculinos del periodo Temprano (antes del 800 DC) y la ausencia completa de la lesión en individuos del periodo Tardío (después del 800 DC). Este declive agudo coincide con la reducción de adornos de conchas marinas talladas encontrados en contextos arqueológicos costeros del Golfo de Panamá, sugiriendo que la práctica del buceo se redujo de manera considerable con el paso del tiempo y, posiblemente, representa una reducción de la demanda de conchas marinas a nivel local y regional.