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 Nitrogen and phosphorus are essential elements for the growth and performance of organisms, and the environmental N:P ratio can determine the biomass and structure of algal communities. We investigated the effects in the N:P molar ratio changes on epipelon and phytoplankton chlorophyll-a under eutrophic conditions. An enrichment experiment was performed in open-bottom mesocosms to simulate P limitation, N limitation, and good N and P availability. Under eutrophic conditions, the combined availability of N and P enhanced phytoplankton bloom, while an increase in P limitation resulted in the loss of phytoplankton biomass. Under conditions of high P limitation, there was significantly loss of epipelon biomass. No change in the N:P ratio led to a significant increase in algal biomass in the epipelon. In conclusion, changes in the N:P molar ratio can affect the growth of phytoplankton and epipelic algae under eutrophic conditions. Our results suggest that photosynthetic biomass increase in the epipelon depends on an optimal relationship between light and P. organisms NP communities chlorophylla chlorophyll openbottom open bottom bloom conclusion

RESUMO Nitrogênio e o fósforo são elementos essenciais para o crescimento e desempenho dos organismos e a razão N:P ambiental pode determinar a biomassa e estrutura das comunidades algais. Nós investigamos os efeitos de mudanças na razão molar N:P sobre a clorofila-a do epipelon e fitoplâncton em condições eutróficas. Em mesocosmos de fundo aberto, realizou-se um experimento de enriquecimento para simular a limitação de P, limitação de N e boa disponibilidade de N e P. Em condições eutróficas, a disponibilidade combinada de N e P intensificou a floração do fitoplâncton, enquanto um aumento na limitação de P resultou em perda na biomassa do fitoplâncton. Sob condições de alta limitação de P, houve perda significativa da biomassa do epipélon. Nenhuma mudança na relação N:P levou a um aumento significativo na biomassa algal no epipélon. Em conclusão, mudanças na razão molar N:P podem afetar o crescimento do fitoplâncton e algas epipélicas em condições eutróficas. Nossos resultados sugerem que um aumento na biomassa fotossintética no epipélon depende de uma relação ótima entre luz e disponibilidade de P. NP algais clorofilaa clorofila eutróficas aberto realizouse realizou se conclusão

Abstract The littoral zone is an essential compartment for lake biota because of its high productivity and diversity. Moreover, phytoplankton is expected to have non-equilibrium dynamics on it. The study’s aimed to explore phytoplankton in the littoral zone of a shallow lake over a short-term scale. Daily sampling was conducted for 25 consecutive summer days in 2016, at two marginal points of a continuously warm, polymictic, and oligo-mesotrophic subtropical lake (Lake Mangueira, Brazil). Cyanobacteria and Chlorophyta contributed 86% of total biomass. We observed high variability in phytoplankton structure, with species turnover over diel cycles. Redundancy analysis indicated spatial differentiation for phytoplankton structure in relation to abiotic conditions. Nutrient dynamics and humic substances were significant drivers for phytoplankton variability. Phytoplankton was positively correlated with SRP and negatively with humic substances. Our results showed a non- equilibrium state for the littoral phytoplankton of Lake Mangueira, given the high variability of abiotic conditions, even at short distances. Due to its high temporal and spatial variability, the littoralzone seems to contribute to the recruitment and maintenance of phytoplankton biodiversity in shallow lakes. Further studies should consider the functional attributes of species and the complex biological interactions of phytoplankton and macrophytes along the littoral zone. diversity Moreover nonequilibrium non it studys study s shortterm term scale 2 2016 warm polymictic oligomesotrophic oligo mesotrophic Mangueira Brazil. Brazil . Brazil) 86 biomass cycles conditions distances lakes 201 8 20

Resumo A utilização de índices é indicada no monitoramento e avaliação permanente de ecossistemas aquáticos, pois eles sintetizam a complexidade técnica do resultado das variáveis e traduzem esses resultados em classes de qualidade, refletindo ações implementadas e apontam caminhos para a recuperação e conservação de recursos. Índices do estado trófico do ambiente fornecem uma visão sobre como nutrientes, disponibilidade de luz e outros fatores estimulam o desenvolvimento da biomassa algal contribui para o aumento do enriquecimento da condição dos sistemas aquáticos. O Índice do Estado Trófico (IET) Lamparelli diferencia ambientes lênticos (menor produtividade fitoplanctônica) e lóticos (maiores concentrações de Fósforo e menores concentrações de Clorofila-a). O Índice de Proteção da Vida Aquática (IVA) reflete a qualidade da água com base no estado trófico do ambiente, determina o grau de toxicidade para a biota e ainda indica deficiência em variáveis e condições essenciais para a proteção da vida aquática. Os índices foram aplicados a uma longa série de dados no monitoramento do Reservatório Guarapiranga, um reservatório urbano, localizado no Estado de São Paulo, sudeste do Brasil, que sofre com ocupação urbana em seu entorno e aporte de efluentes domésticos. A avaliação da série temporal de 1978 a 2021 com esses índices mostrou piora na condição trófica e de preservação da vida aquática no reservatório e em um dos tributários. Considerando que a avaliação conjunta dos dois índices fornece um enfoque de conservação ambiental, sua utilização em longo prazo refletiu alterações e impactos ao ambiente, mostrando ainda os locais mais conservados. Os resultados mostraram que os dois índices são indicados para aplicação em uma rede básica em ambientes subtropicais, aptos a indicar locais para aprimoramento do monitoramento e sensíveis às alterações ambientais. aquáticos recursos nutrientes IET (IET menor fitoplanctônica maiores Clorofilaa. Clorofilaa Clorofila . Clorofila-a) IVA (IVA Guarapiranga urbano Paulo Brasil domésticos 197 202 tributários ambiental conservados subtropicais ambientais Clorofila-a 19 20 1 2

Abstract The use of indices is recommended for continuous monitoring and assessment of aquatic ecosystems, as they summarize the technical complexity of the results of multiple analyzes performed and translate these results into quality classes that reflect the actions taken and indicate ways to recover and conserve the resources. Environmental trophic state indices provide information on how nutrients, light availability and other factors promote the development of algal biomass and contribute to increased enrichment status of aquatic systems. Lamparelli's Trophic State Index (TSI) distinguishes between lentic (lower phytoplankton productivity) and lotic (higher phosphorus concentrations and lower chlorophyll-a concentrations) environments. The Aquatic Life Protection Index (ALPI) reflects water quality based on the trophic state of the environment, determines the degree of toxicity to biota and indicates deficiencies in variables and conditions essential for the protection of aquatic life. The indices were applied to a long data series to monitor the Guarapiranga Reservoir, an urban reservoir in the state of São Paulo in southeastern Brazil, which suffers from the urbanization of its surroundings and the discharge of domestic wastewater. The evaluation of the time series from 1978 to 2021 using these indices showed a deterioration in the trophic status and conservation of aquatic life in the reservoir and in one of its tributaries. Considering that the joint assessment of the two indices provides an approach to environmental conservation, their long-term use reflected changes and impacts on the environment and showed the best-preserved sites. Both indices are suitable for application in a baseline network in subtropical environments. They can pinpoint locations for better monitoring and are sensitive to environmental changes. ecosystems resources nutrients systems Lamparellis Lamparelli s TSI (TSI productivity higher chlorophylla chlorophyll environments ALPI (ALPI Reservoir Brazil wastewater 197 202 tributaries longterm term bestpreserved best preserved sites 19 20 1 2

Abstract: Aim To explore the short-term effects of rainfall events on the biomass, density, and richness of the phytoplankton community during dry and rainy periods, as well as on the selection and response of Morphology-Based Functional Groups (MBFG). Methods The phytoplankton community and abiotic environmental variables were sampled over a short period in a subtropical urban lake during the dry and rainy seasons (2018-2019). Generalized Linear Models (GLMs) were generated to analyze the relationship between phytoplankton biovolume, density, and richness with abiotic variables. The predictability of phytoplankton functional groups was assessed using Redundancy Analysis (RDA). Results There was an increase in the density and biovolume of the phytoplankton community during the rainy period. Species richness decreased with increased rainfall. The lake exhibited a high dominance of Cyanobacteria (MBFG VIII), mainly represented by Raphidiopsis raciborskii (Woloszynska) Aguilera in both periods studied. Conclusions We found evidence supporting the hypothesis that rainfall events increase the density and biovolume of phytoplankton. Morphology-based functional groups served as efficient indicators of the lake's environmental conditions. Abstract shortterm term biomass MorphologyBased Morphology Based MBFG. MBFG . (MBFG) 20182019. 20182019 2018 2019 (2018-2019) GLMs (GLMs RDA. RDA (RDA) VIII, VIII , VIII) Woloszynska (Woloszynska studied Morphologybased based lakes s conditions 2018201 201 (2018-2019 (RDA 201820 20 (2018-201 20182 2 (2018-20 (2018-2 (2018- (2018 (201 (20 (2 (

Resumo: Objetivo Explorar os efeitos a curto prazo de eventos de chuva na biomassa, densidade e riqueza da comunidade fitoplanctônica durante os períodos seco e chuvoso, bem como na seleção e resposta de Grupos Funcionais Baseados na Morfologia (MBFG). Métodos A comunidade fitoplanctônica e as variáveis ambientais abióticas foram amostradas em um curto período em um lago urbano subtropical durante as estações seca e chuvosa (2018-2019). Modelos Lineares Generalizados (GLMs) foram gerados para analisar a relação entre o biovolume, a densidade e a riqueza do fitoplâncton com as variáveis abióticas. A previsibilidade dos grupos funcionais de fitoplâncton foi avaliada usando Análise de Redundância (RDA). Resultados Houve um aumento da densidade e do biovolume da comunidade fitoplanctônica no período chuvoso. A riqueza de espécies diminuiu com o aumento da pluviosidade. O lago exibiu uma alta dominância de Cyanobacteria (MBFG VIII), principalmente representadas por Raphidiopsis raciborskii (Woloszynska) Aguilera nos dois períodos estudados. Conclusões Encontramos evidências que sustentam a hipótese de que eventos de chuva aumentam a densidade e o biovolume do fitoplâncton. Os grupos funcionais baseados na morfologia serviram como indicadores eficientes das condições ambientais do lago. Resumo biomassa chuvoso MBFG. MBFG . (MBFG) 20182019. 20182019 2018 2019 (2018-2019) GLMs (GLMs RDA. RDA (RDA) pluviosidade VIII, VIII , VIII) Woloszynska (Woloszynska estudados 2018201 201 (2018-2019 (RDA 201820 20 (2018-201 20182 2 (2018-20 (2018-2 (2018- (2018 (201 (20 (2 (

Abstract Bioseston is a heterogeneous assemblage of bacterioplankton, phytoplankton, zooplankton, and planktonic debris. A detailed knowledge of biosestons is essential for understanding the dynamics of trophic flows in marine ecosystems. The distributional features of seston biomass in plankton (micro- and mesoplankton) in the Southwest Atlantic Ocean (Rio de Janeiro State, Brazil) were analyzed using stratified samples gathered to a depth of 2,400 m during night time. The horizontal pattern of biomass distribution was analyzed vis-a-vis station depth during both wet and dry periods, with higher values recorded in the continental shelf than in the slope, confirming the terrestrial contribution of nutrient sources to the marine environment. This horizontal variation reinforces the occurrence of seasonal vortices in Cabo Frio and Cabo de São Tomé on the central coast of Brazil. Environmental variables reflect the hydrological signatures of the water masses along the Brazilian coast. The largest seston biomass was related to high temperatures, salinities, and low inorganic nutrient concentrations in tropical and South Atlantic central waters. The observed distribution patterns suggest that seston biomass in plankton in the region may be structured based on partitioned horizontal and vertical habitats and food resources. bacterioplankton phytoplankton zooplankton debris ecosystems micro (micro mesoplankton Rio State Brazil 2400 2 400 2,40 time visavis vis periods slope environment temperatures salinities waters resources 240 40 2,4 24 4 2,

Abstract The Brazil-Malvinas Confluence (BMC) is a significant biological frontier where distinct currents meet, fostering optimal conditions for phytoplankton development. In this study we tested the hypothesis that eddys promote an increase in phytoplankton biomass at the Brazil-Malvinas Confluence (BMC), altering species diversity. Phytoplankton were collected with Niskin bottles and nutrient concentrations assessed at two depths (Surface and Deep Chlorophyll Maximum Layer – DCML) in areas outside and under the influence of Cold-Core (CCE) and Warm-Core (WCE) Eddies. Environmental variables were determined in situ using a CTD profiler. Four regions were separated based on environmental variables and phytoplankton species, namely, the Brazil Current (BC), Malvinas Current (MC), CCE, and WCE. Species diversity was higher in the eddies. The conditions of the WCE were different from those of the CCE, with low temperature and salinity and high cell density values in the latter. The phylum Bacillariophyta was predominant in terms of species richness in all regions and was responsible for the higher cell density in the MC, while dinoflagellates were dominant in the BC and eddies. Therefore, eddy activity alters the structure, diversity and biomass of the phytoplankton community in the BMC. BrazilMalvinas BMC (BMC meet development BMC, , Surface DCML ColdCore Cold Core CCE (CCE WarmCore Warm (WCE Eddies profiler namely BC, (BC) MC (MC) eddies latter Therefore structure (BC (MC

Abstract In order to determine the structure and biomass of phytoplankton (picophytoplankton, nanodiatoms, and microdiatoms) under oligotrophic conditions, a study was carried out in the surface layer of the Guaymas Basin, Gulf of California, during the late summer of 2016. This study included the measurement of hydrographic, chemical, and biological variables in the surface layer of the study area. Our results showed a warm, strongly stratified, and nutrient-depleted water column associated with reduced phytoplankton biomass (<1 mg Chla·m-3). The average ratios of N:P (0.55 ± 1.34), N:Si (0.13 ± 0.18), and Fe:N (52.70 ± 29.70) indicate N-limiting conditions. The biomass contribution of phytoplankton groups fluctuated widely by depth level, with predominance of picophytoplankton (85.0 ± 2.7%) at the surface (5 m) and nano-microdiatoms (91.5 ± 5.9%) at the deepest level (35-40 m), adjacent to the thermocline. Diatoms dominated the integrated biomass between the surface and 50-m depth, with an average contribution ~6 times greater than that of picophytoplankton. Despite the ideal conditions for the proliferation of diazotrophs, the presence of Trichodesmium spp. and Richelia intracellularis was very irregular and in relatively low abundances (2,220 ± 1,575 cell·L-1). Our results are especially relevant as they suggest that, under N-limiting conditions, the paradigm of high biomass and large cell dominance in the Gulf of California may be challenged during the summer season.

Resumen Con el propósito de determinar la biomasa y la composición del fitoplancton (picofitoplancton, nanodiatomeas y microdiatomeas) bajo condiciones oligotróficas, se realizó un estudio en la capa superficial de la cuenca de Guaymas, golfo de California, durante el verano tardío de 2016. El estudio contempló la medición de variables hidrográficas, químicas y biológicas en la capa superficial del área de estudio. Nuestros resultados mostraron una columna de agua cálida, fuertemente estratificada, empobrecida en nutrientes y con biomasas fitoplanctónicas reducidas (<1 mg Cla·m-3). Los cocientes promedio de N:P (0.55 ± 1.34), N:Si (0.13 ± 0.18) y Fe:N (52.70 ± 29.70) indicaron condiciones de limitación por N. La contribución de los grupos fitoplanctónicos a la biomasa fluctuó ampliamente por nivel de profundidad, y se observó el predominio del picofitoplancton (85.0 ± 2.7%) en superficie (5 m) y de las nano-microdiatomeas (91.5 ± 5.9%) en el nivel más profundo (35-40 m), adyacente a la termoclina. Las diatomeas dominaron la biomasa integrada entre la superficie y 50 m de profundidad, con una contribución promedio ~6 veces mayor que la del picofitoplancton. A pesar de que se registraron condiciones ideales para la proliferación de cianobacterias diazótrofas, la presencia de Trichodesmium spp. y Richelia intracellularis fue muy irregular y en abundancias relativamente bajas (2,220 ± 1,575 célula·L-1). Nuestros resultados son especialmente relevantes, ya que sugieren que, bajo condiciones de limitación por N, el paradigma de la alta biomasa y dominancia de células grandes en el golfo de California puede verse desafiado durante la temporada de verano.

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.

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.

A survey of the quality of water flowing from micro-system types to the ocean, along the subtropical east coast of South Africa, showed a wide variation in the concentrations of total nitrogen, phosphorus and phytoplankton biomass in the different systems located, in many cases, only a short distance from each other along the coastline. The origins of the high phytoplankton growth indicate pollutants caused by the land-use in this highly populated coastal region. The main agricultural activities in the area are sugarcane, permanent orchards, and forestry. The levels of N and P in the water varied from 'good' to 'poor', i.e., TN 0.15-3.99 mg-L-1, TP 0.02-0.33 mg-L-1 and chlorophyll-a from 0 to almost 45 Mg-L-1. Rapid coastal population densification appears to have been the cause of the pollution levels measured for total nitrogen, phosphorus, and phytoplankton biomass. Most of the micro-systems with a total modified peri-catchment above 80% were enriched by both TN and TP. While the hypothesis tested was that the main cause was residential development (e.g., septic tank effluent), it was not possible to show any statistical significance to support such a specific conclusion. Although these systems are small individually, the great number along the coastline warrants recognition as important sources of freshwater inflow and nutrients to the marine environment.

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.

ABSTRACT Within the last decades, phytoplankton biomass has significantly risen in many lakes worldwide. Global warming was proposed as the most probable cause of the discovered effect. In this work, attention was paid to other drivers than just global warming, in particular, variability in solar radiation to explain this unexpected diatom shift. Here, we use a combination of paleolimnological, dendrochronological and meteorological datasets, as well as local pollution information, to analyze the recent growth of diatom total abundance in Lake Rabbvatnet (69.7º N, 30.5º E, Northern Norway). The results show that the diatoms of the genus Aulacoseira were most abundant in the top layers of the sediment core. On the contrary, the biomass of small-sized Cyclotella species, which, as a rule, should grow simultaneously with warming, has decreased over the past decades. We suggest basing on the experimental data analysis (comparison of diatom abundance with solar irradiance and heavy metals, testing of air temperature trends) that the recent growth of the total diatom abundance observed in the subarctic Rabbvatnet Lake could be mainly due to an increase in photosynthetically active spectral solar irradiance fluxes in the visible and infrared ranges. decades worldwide effect work particular shift Here paleolimnological datasets information 69.7º 697º º 69 7º N 305º 30 5º E Norway. Norway . Norway) core contrary smallsized small sized species which rule comparison metals trends ranges 6 3

Abstract We evaluate how the concentrations of inorganic nutrients and chlorophyll a vary in a heterogeneous area (Equatorial SW Atlantic), covering a gradient from stations closer to the coast to others more distant associated or not with turbid-zone reefs. Vertical temperature (27.9 ± 0.10 °C; mean ± standard deviation) and salinity (36.2 ± 0.14) profles showed that the water column is well mixed (0-30 m depth). The oligotrophic condition was marked by low concentrations of phosphate (0.30 ± 0.22 µM) and dissolved inorganic nitrogen (0.64 ± 0.74 µM). Moreover, dissolved reactive silicon (DSi) was low in most samples (< 2.0 µM), but higher (>10 µM) in nearshore stations, probably related to continental runoff and/or resuspension of the bottom sediments. The pelagic phytoplankton biomass indicated that chlorophyll a (0.25 ± 0.08 µg L-1) was low, positively correlated with light and negatively correlated with nutrients, indicating possible phytoplankton uptake. Chlorophyll a concentrations were lower in stations closer to the coast and higher in some stations near the reefs, indicating that the latter could be more prone to phytoplankton development and depletion of nutrients, especially DSi. Therefore, although oligotrophy is present along this coast, we found some unexpected heterogeneity of nutrient and chlorophyll a distributions, which were probably infuenced by benthic-pelagic coupling due to the presence of extensive reefs, sponge gardens (18-30 m depth), and the proximity to the coast. These results highlight the importance of understanding the heterogeneity of ocean productivity, especially in lesser known low-latitude areas, which showed distinct nutrient and chlorophyll a levels related to the occurrence of tropical reefs that are capable of supporting important fsh stocks and unique biological communities. Equatorial Atlantic, Atlantic , Atlantic) turbidzone turbid zone 27.9 279 27 9 (27. 010 0 10 0.1 °C C deviation 36.2 362 36 2 (36. 0.14 014 14 030 30 (0-3 depth. depth . depth) 0.30 (0.3 022 22 0.2 µM 0.64 064 64 (0.6 074 74 0.7 µM. Moreover DSi (DSi < ( 20 2. µM, >10 (>1 andor sediments 0.25 025 25 (0.2 008 08 0.0 L1 L 1 L-1 uptake Therefore distributions benthicpelagic benthic 1830 18 (18-3 depth, productivity lowlatitude latitude areas communities 27. (27 01 0. 36. 3 (36 03 (0- 0.3 (0. 02 0.6 06 6 07 7 >1 (> 00 L- 183 (18- (2 (3 (0 > (18 (1

Abstract: Aim Zooplankton functional groups play an important role in lake functioning and can readily respond to environmental changes and may be associated with phytoplankton changes. In warmer regions, zooplankton species have a smaller body size, which decreases their grazing capacity, attenuating top-down control throughout phytoplankton. We evaluated changes in density and biomass of zooplankton functional groups and their relationship with algal groups in horizontal reservoir zonation (pelagic, sublittoral, and eulittoral zones) of the shallow reservoir. We hypothesize that the density and biomass of zooplankton functional groups are associated with fluctuations in the phytoplankton groups in horizontal reservoir zonation. Methods Changes in the structure of the zooplankton functional group and the controlling limnological variables were verified at three sampling stations: pelagic, sublittoral, and eulittoral zones in a mesotrophic reservoir. Results Zooplankton species were distributed in seven functional groups. The density and biomass of zooplankton functional groups were not clearly associated with biomass variations of phytoplankton groups. However, the zooplankton functional groups were associated with horizontal reservoir zonation, where specific groups were found in the pelagic, sublittoral, and eulittoral zones. Conclusions The zooplankton functional groups were related to the horizontal zonation of the reservoir but were not associated with changes in the phytoplankton groups due to the dominance of small organisms. Abstract regions size capacity topdown top down pelagic (pelagic sublittoral stations However organisms

Resumo: Objetivo Os grupos funcionais do zooplâncton desempenham um papel importante no funcionamento dos lagos, são capazes de responder prontamente às mudanças ambientais e podem estar associados às mudanças no fitoplâncton. Em regiões mais quentes, as espécies de zooplâncton apresentam pequeno tamanho corporal, o que diminui sua capacidade de pastejo e atenua o controle de cima para baixo sobre o fitoplâncton. Avaliamos as mudanças na densidade e biomassa de grupos funcionais do zooplâncton e sua relação com grupos de algas na zonação horizontal de um reservatório raso (zona pelágica, sublitoral e eulitoral). Nossa hipótese é que a densidade e biomassa dos grupos funcionais do zooplâncton estão associadas a flutuações nos grupos do fitoplâncton no zoneamento horizontal do reservatório. Métodos Em um reservatório mesotrófico, as alterações na estrutura do grupo funcional do zooplâncton e nas variáveis limnológicas foram avaliadas em três zonas de amostragem: pelágica, sublitoral e eulitoral. Resultados As espécies de zooplâncton foram distribuídas em sete grupos funcionais. Evidenciou-se que a densidade e a biomassa dos grupos funcionais do zooplâncton não foram claramente associadas às variações da biomassa dos grupos do fitoplâncton. No entanto, os grupos funcionais do zooplâncton foram associados à zonação horizontal do reservatório, onde grupos específicos foram encontrados na zona pelágica, sublitoral e eulitoral. Conclusões Os grupos funcionais do zooplâncton foram relacionados com a zonação horizontal do reservatório, mas não foram associados às mudanças nos grupos do fitoplâncton devido à dominância de organismos de pequeno porte. Resumo lagos quentes corporal pelágica eulitoral . eulitoral) mesotrófico amostragem Evidenciouse Evidenciou se entanto porte