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.

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 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.

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 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

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

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 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-

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

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. 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.

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 Introduction: The increased oceanic temperature associated with climate change has augmented the activity of tropical cyclones globally. These meteorological phenomena induce substantial physicochemical perturbations on oceans with implications for the phytoplankton communities. The latter, are drifting photosynthetic microorganisms, which are the basis of the oceanic trophic webs. Besides, they modulate climate processes, biogeochemical cycles and influence fishery yields. The general objective of this work was to assess the response of phytoplankton and their environmental drivers to the passage of hurricanes (strongest tropical cyclones) in the North Atlantic in the period 1998-2019. Methods: They were used satellite observations and outputs of mathematical models as data sources since the extreme meteorological conditions associated with these phenomena limit the collection of field data. Results: They were characterized the phytoplankton response as well as their environmental drivers (e.g., sea surface temperature, depth of the mixed layer, upwelling, marine currents) to the passage of hurricanes across the waters of the Exclusive Economic Zone of Cuba, the Gulf of Mexico and the Sargasso Sea. In general, hurricanes induce a significant increase of the phytoplankton biomass and diversity in the oligotrophic environments in the North Atlantic, due to the increased nutrient concentrations, which fuel their photosynthesis. Additionally, the horizontal transport of coastal waters induced by these phenomena leads to a fertilization of the oligotrophic environments enhancing the ecological connectivity in the region. Conclusions: Hurricanes can be seen as drivers of the phytoplankton productivity and diversity in the North Atlantic. The results obtained are an important baseline to guide and stimulate future research on climate change, ecology and/or environment in the region.

RESUMEN Introducción: El aumento de la temperatura oceánica asociado al cambio climático ha incrementado la actividad de los ciclones tropicales a nivel global. Estos fenómenos meteorológicos inducen perturbaciones fisicoquímicas en los océanos con profundas implicaciones para las comunidades de fitoplancton. Los últimos son microorganismos fotosintéticos flotantes que constituyen la base de las redes tróficas oceánicas, modulan procesos climáticos y ciclos biogeoquímicos e influencian los rendimientos pesqueros. El presente trabajo tiene como objetivo general evaluar la respuesta del fitoplancton y sus impulsores ambientales al paso de huracanes (ciclones tropicales más intensos) en el Atlántico Norte en el período 1998-2019. Métodos: Se utilizaron observaciones satelitales y salidas de modelos matemáticos como fuentes de datos ya que las condiciones meteorológicas extremas asociadas a estos fenómenos limitan la adquisición de los datos de campo. Resultados: Se caracterizó la respuesta del fitoplancton y sus impulsores ambientales (temperatura superficial del mar, profundidad de la capa mezclada, surgencia, corrientes marinas, entre otros) al paso de huracanes en las aguas de la Zona Económica Exclusiva de Cuba, el Golfo de México y el Mar de los Sargazos. Los huracanes provocan el incremento significativo de la biomasa del fitoplancton y de la diversidad de sus comunidades en los ambientes oligotróficos del Atlántico Norte debido al incremento de la concentración de nutrientes que estimula su actividad fotosintética. El transporte horizontal de aguas costeras inducido por estos fenómenos contribuye a fertilizar los ambientes oligotróficos potenciando la conectividad ecológica en la región. Conclusiones: Los huracanes pueden ser considerados impulsores de la productividad y diversidad del fitoplancton en el Atlántico Norte. Los resultados obtenidos son importantes pues brindan una línea base para el desarrollo de futuras investigaciones sobre cambio climático, ecología y medio ambiente en la región.

ABSTRACT Background. Corals and coral reefs of the eastern Pacific are distributed discontinuously from the Gulf of California to Huatulco, Mexico, and from Los Cóbanos, El Salvador, to northern Peru. The most southeastern coral community in the Mexican Pacific was Tejoncito (Huatulco Bays); however, recent surveys extend the distribution to La Blanca Island. Objective. To make known the characteristics, conditions, and fauna associated with the coral community of La Blanca Island. Methods. During 2016, surveys were conducted around La Blanca Island, where a small coral community was in the northern portion but not in the east and west. Results. The coral community is located at approximately 3 m depth and under a strong current; it is small and characterized by a relatively low coral cover (10 %) of the species Pocillopora damicornis, Pocillopora capitata, and Pocillopora verrucosa. Three coral species, 13 echinoderm species, and 50 fish species were recorded, all commonly associated with coral communities and reefs of the eastern tropical Pacific. The presence of corals on La Blanca Island is relevant because it corresponds to the most southeastern record in the Mexican Pacific (55 km East of Tejoncito, in the area of Huatulco Bays); the record is striking because it is located in a region with strong upwelling, high productivity, drastic changes in water temperature and low pH and Ωarag values, all of which are not very favorable for larval settlement, coral growth, and the development of coral communities. Conclusions. The current record not only broadens the spatial distribution range of corals and coral communities in the Mexican Pacific but also represents an opportunity to study the development of reef-building corals under harsh environmental conditions.

RESUMEN Antecedentes. Los corales y arrecifes coralinos del Pacífico oriental se distribuyen de manera discontinua desde el Golfo de California hasta Huatulco, México y de Los Cóbanos, El Salvador hasta el norte de Perú. Se consideraba que la comunidad coralina más suroriental en el Pacífico mexicano era El Tejoncito (bahías de Huatulco); sin embargo, recientes prospecciones extienden la distribución a isla La Blanca. Objetivo. Dar a conocer las características, condición y fauna asociada a la comunidad coralina de isla La Blanca. Métodos. Durante 2016 se realizaron prospecciones alrededor de isla La Blanca en donde se ubicó una pequeña comunidad coralina en la porción norte, no así en su parte este y oeste. Resultados. La comunidad coralina se encuentra aproximadamente a 3 m de profundidad y bajo una fuerte corriente, es pequeña y está caracterizada por una relativa baja cobertura de coral (10 %) de las especies Pocillopora damicornis, Pocillopora capitata y Pocillopora verrucosa. Se registraron tres especies de corales, 13 de equinodermos y 50 de peces, todos ellos comúnmente asociados a comunidades y arrecifes coralinos del Pacífico oriental tropical. La presencia de corales en isla La Blanca es de relevancia pues corresponde al registro más suroriental en el Pacífico mexicano (55 km al oriente de Tejoncito, en el área de bahías de Huatulco); el registro llama la atención por ubicarse en una región con fuertes surgencias, alta productividad, cambios drásticos en la temperatura del agua y con valores bajos de pH y Ωarag, características, todas ellas, poco favorables para el asentamiento de larvas, crecimiento de corales y el desarrollo de comunidades coralinas. Conclusiones. El presente registro no solo amplía el rango de distribución espacial de los corales y comunidades coralinas del Pacífico mexicano, representa una oportunidad para estudiar el desarrollo de corales formadores de arrecifes en condiciones ambientales poco propicias.

Resumen: La extracción activa del erizo de mar Lytechinus variegatus en el noreste de Venezuela podría conllevar a una reducción de su densidad poblacional. Por consiguiente, el conocimiento sobre el crecimiento somático y la producción gonadal es de importancia para la explotación racional y el manejo sustentable de sus poblaciones. Durante un ciclo anual, este estudio examinó la biología reproductiva e índices moleculares de crecimiento (ARN:ADN y Proteína:ADN) de una población del erizo L. variegatus en el Golfo de Cariaco (Venezuela); un ecosistema marino regulado por las temporadas de estratificación y surgencia costera. La población de erizos de mar presentó tallas homogéneas, con incrementos significativos en la masa fresca total (MF) y el índice gonadosomático (IG) durante la estratificación. Se obtuvieron modelos de regresión significativos durante los periodos de surgencia y estratificación, particularmente entre la MF en relación con las dimensiones de la testa y linterna de Aristóteles. El desarrollo gonadal fue continuo, mostrando desoves parciales durante el período de surgencia. El cociente ARN:ADN incrementó durante la temporada de estratificación, no así el cociente Proteína:ADN. El Análisis de Componentes Principales indicó asociación entre los índices moleculares de crecimiento con el seston, contrariamente a la biomasa fitoplanctónica, y la temperatura superficial del agua. El ciclo reproductivo del L. variegatus presentó un patrón estacional asociado a la temperatura y productividad primaria; desova activamente durante la temporada de surgencia, y la gametogénesis se potencia durante la estratificación, cuando son mayores los procesos metabólicos.

Abstract: Active extraction of sea-urchin Lytechinus variegatus from the northeast of Venezuela could cause a reduction in the populational density. Therefore, knowledge about somatic growth and gonadal production is relevant for the rational exploitation and sustainable management of sea-urchin populations. During an annual cycle, this study examined the reproductive biology and growth molecular indices (RNA:DNA and Protein:DNA) of a population of L. variegatus sea-urchin from Cariaco Gulf (Venezuela); a marine ecosystem influenced by the seasons of stratification and coastal upwelling. Sea-urchin population was composed of homogeneous sizes, with significant increase of the total fresh mass (MF) and gonadosomatic index (IG) during stratification. Significant regression models were obtained during upwelling and stratification periods, particularly among the MF with testa dimensions and Aristotle’s lantern. Gonadal development was continuous, showing partial spawning during the upwelling period. RNA:DNA ratio increased during stratification season, but not Protein:DNA index. Principal Component Analysis indicated association among molecular growth indices with seston, conversely to phytoplankton biomass, and seawater surface temperature. Reproductive cycle of L. variegatus presented a seasonal pattern associated with temperature and primary productivity; particularly during upwelling it actively spawns, and the gametogenesis is enhanced during stratification, when the metabolic processes are greater.

ABSTRACT This study analyzes the spatial and temporal variability of phytoplankton biomass and taxonomic composition in the surface waters of Todos Santos Bay, a semi-enclosed bay within the upwelling zone of the Baja California peninsula (México). Two methodological approaches (microscopy and chemotaxonomy [CHEMTAX]) were used to describe the variability of some genera and species (observed under the microscope) and the importance of those groups that cannot be observed microscopically. Phytoplankton biomarker pigments were measured with high-resolution liquid chromatography and used as input to run the CHEMTAX software to determine the contribution of the main phytoplankton groups to chlorophyll-a (Chl-a). The microscopic analyses showed that diatoms and dinoflagellates comprised 65 and 33% of the total cells, respectively. Dinoflagellates were most abundant in the inner bay and during cold months; the most frequent and abundant genera were Tripos, Protoperidinium, and Prorocentrum. Among diatoms, the most frequent genera were Cylindrotheca, Guinardia, Navicula, Pseudo-nitzschia, and Chaetoceros. CHEMTAX indicated that, together with diatoms, the flagellates prymnesiophytes and chlorophytes contributed a median of 80% to Chl-a, with chlorophytes as the most important group (29.9%). The high contribution of these flagellates suggests that they are represented by small-sized cells not visible by the light microscopy used. However, CHEMTAX largely underestimated the contribution of dinoflagellates (due to the presence of many mixotrophic species). Hence, our results emphasize the importance of using both techniques for a more detailed evaluation of the taxonomic composition of phytoplankton in this and other coastal regions.