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RESUMEN El objetivo de esta investigación fue establecer el biofloc a tres relaciones carbono/ nitrógeno (C/N): 10/1, 15/1 y 20/1, determinando la secuencia de remoción de N, el perfil de sólidos y la caracterización del zooplancton, para tal fin se dispuso de tres tanques con volumen de 7000 L, incorporando oxígeno al agua a través de un aireador tipo soplador. Se utilizó como fuente de N balanceado, fuente de carbono melaza y bicarbonato de sodio como fuente alcalinizante. Al inicio se incrementó el nitrógeno amoniacal total NAT a 2 mg/L, la alcalinidad total (AT) a 120 mg/L y se adicionó como inóculo 10 litros/tanque de agua proveniente de un estanque de cultivo, al sexto y décimo días se adicionó balanceado incrementando teóricamente el NAT en 4 mg/L y a partir del día 12 en 1 mg/L. En las tres relaciones C/N se evidenciaron procesos de nitrificación durante la estabilización del biofloc, hasta llegar en el tiempo a concentraciones no letales de amonio y nitrito para peces, menores a 1 mg/L. En cuanto a los sólidos volátiles, se encontró una mayor concentración en la relación 20/1, lo cual puede atribuirse a la mayor adición de melaza, con la consecuente producción de SSV a partir de la dominancia de comunidades heterotróficas, en los tres macrocosmos se presentaron comunidades del zooplancton, no obstante, el T2 presentaron la mayor abundancia y riqueza de organismos. Las tres relaciones C/N en biofloc establecieron condiciones de calidad de agua y alimento vivo.
ABSTRACT The objective of this research was to establish the biofloc at three carbon/nitrogen (C/N) relationships: 10/1, 15/1 and 20/1, determining the N removal sequence, the solids profile and the characterization of the zooplankton, for this purpose three tanks with a volume of 7000 L were available, incorporating oxygen into the water through a blower-type aerator. It was used as a source of balanced N, a source of carbon molasses and sodium bicarbonate as an alkalizing source. At the beginning, the total ammoniacal nitrogen NAT was increased to 2 mg/L, the total alkalinity (AT) to 120 mg/L and 10 liters / tank of water from a culture pond was added as inoculum, on the sixth and tenth days it was he added balanced, theoretically increasing the NAT by 4 mg/L and from day 12 by 1 mg/L. In the three C / N relationships, nitrification processes were evidenced during the stabilization of the biofloc, until reaching non-lethal concentrations of ammonium and nitrite for fish, less than 1 mg/L in time. Regarding volatile solids, a higher concentration was found in the 20/1 ratio, which can be attributed to the greater addition of molasses, with the consequent production of SSV from the dominance of heterotrophic communities, in the three macrocosms there were Zooplankton communities, however, T2 presented the highest abundance and richness of organisms. The three C / N relationships in biofloc established conditions of water quality and live food.
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A first checklist of Rotifera species in freshwater environments in Bahia State, in northeastern Brazil, is provided. The list includes sampling data from 26 aquatic environments (lotic and lentic) undertaken from 2010 to 2016. One hundred and fifty-five species were recorded, with 68 new records for the state. The family Brachionidae and Lecanidae were the most representative (54.8%). The greatest richness was recorded in the Colônia River (57 species). Those results reflect the low numbers of studies previously undertaken in the region, indicating more research needs to be focused on Rotifera biodiversity in Bahia, the fifth largest state in Brazil (567,295 km2) with large numbers of freshwater bodies.
É fornecida uma primeira lista de verificação das espécies de Rotifera em ambientes de água doce no Estado da Bahia, nordeste do Brasil. A lista de espécies inclui dados de amostragem de 26 ambientes aquáticos (lóticos e lênticos) de 2010 a 2016. Cento e cinquenta e cinco espécies foram registradas, com 68 novos registros para o estado. As famílias Brachionidae e Lecanidae foram as mais representativas (54,8%). A maior riqueza foi registrada no rio Colônia (57 espécies). Esses resultados provavelmente refletem o número de estudos na região, sugerindo mais pesquisas sobre a biodiversidade de Rotifera na Bahia, o quinto maior estado do Brasil (567.295 km2) com grande número de corpos aquáticos de água doce.
Assuntos
Animais , Rotíferos , Brasil , Biodiversidade , Rios , Água DoceRESUMO
A first checklist of Rotifera species in freshwater environments in Bahia State, in northeastern Brazil, is provided. The list includes sampling data from 26 aquatic environments (lotic and lentic) undertaken from 2010 to 2016. One hundred and fifty-five species were recorded, with 68 new records for the state. The family Brachionidae and Lecanidae were the most representative (54.8%). The greatest richness was recorded in the Colônia River (57 species). Those results reflect the low numbers of studies previously undertaken in the region, indicating more research needs to be focused on Rotifera biodiversity in Bahia, the fifth largest state in Brazil (567,295 km2) with large numbers of freshwater bodies.
É fornecida uma primeira lista de verificação das espécies de Rotifera em ambientes de água doce no Estado da Bahia, nordeste do Brasil. A lista de espécies inclui dados de amostragem de 26 ambientes aquáticos (lóticos e lênticos) de 2010 a 2016. Cento e cinquenta e cinco espécies foram registradas, com 68 novos registros para o estado. As famílias Brachionidae e Lecanidae foram as mais representativas (54,8%). A maior riqueza foi registrada no rio Colônia (57 espécies). Esses resultados provavelmente refletem o número de estudos na região, sugerindo mais pesquisas sobre a biodiversidade de Rotifera na Bahia, o quinto maior estado do Brasil (567.295 km2) com grande número de corpos aquáticos de água doce.
Assuntos
Animais , Rotíferos/classificação , ZooplânctonRESUMO
Abstract A first checklist of Rotifera species in freshwater environments in Bahia State, in northeastern Brazil, is provided. The list includes sampling data from 26 aquatic environments (lotic and lentic) undertaken from 2010 to 2016. One hundred and fifty-five species were recorded, with 68 new records for the state. The family Brachionidae and Lecanidae were the most representative (54.8%). The greatest richness was recorded in the Colônia River (57 species). Those results reflect the low numbers of studies previously undertaken in the region, indicating more research needs to be focused on Rotifera biodiversity in Bahia, the fifth largest state in Brazil (567,295 km2) with large numbers of freshwater bodies.
Resumo É fornecida uma primeira lista de verificação das espécies de Rotifera em ambientes de água doce no Estado da Bahia, nordeste do Brasil. A lista de espécies inclui dados de amostragem de 26 ambientes aquáticos (lóticos e lênticos) de 2010 a 2016. Cento e cinquenta e cinco espécies foram registradas, com 68 novos registros para o estado. As famílias Brachionidae e Lecanidae foram as mais representativas (54,8%). A maior riqueza foi registrada no rio Colônia (57 espécies). Esses resultados provavelmente refletem o número de estudos na região, sugerindo mais pesquisas sobre a biodiversidade de Rotifera na Bahia, o quinto maior estado do Brasil (567.295 km2) com grande número de corpos aquáticos de água doce.
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Abstract The zooplankton communities often exhibit daily vertical migrations to avoid natural ultraviolet radiation and/or fish predation. However there is no information on this topic in Chilean North Patagonian lakes up to date. Therefore, this study deals with a first characterization of plankton crustacean daily vertical migration in two temperate, oligotrophic lakes (Villarrica and Panguipulli lakes, 39°S) in Southern Chile. Zooplankton were collected at different depths intervals (0-10m, 10-20 m, 20-30m, 30-40m) at early morning, middle day, evening and night in the studied site. The results revealed that zooplankton species (Daphnia pulex, Ceriodaphnia dubia, Neobosmina chilensis, Mesocyclops araucanus, and Tropocyclops prasinus) are abundant in surface zones at night, early morning and evening, whereas at middle day the zooplankton abundances are high at deep zones. The results agree with observations for Argentinean and North American lakes where these daily migration patterns in crustacean zooplankton species were reported due mainly natural ultraviolet radiation exposure, whereas for northern hemisphere lakes the vertical migration is due to combined effect of natural ultraviolet radiation and fish predation exposure.
Resumo As comunidades zooplanctônicas frequentemente exibem migrações verticais diárias para evitar a radiação ultravioleta natural e/ou a predação de peixes. No entanto, não há informações sobre esse tema em lagos chilenos no norte da Patagônia até a presente data. Portanto, este estudo trata de uma primeira caracterização da migração vertical diária de crustáceo planctônico em dois lagos temperados e oligotróficos (lagos Villarrica e Panguipulli, 39º S) no sul do Chile. O zooplâncton foi coletado em diferentes profundidades (0-10 m, 10-20 m, 20-30 m e 30-40 m) no início da manhã, ao meio-dia, à tarde e à noite no local estudado. Os resultados revelaram que as espécies de zooplâncton (Daphnia pulex, Ceriodaphnia dubia, Neobosmina chilensis, Mesocyclops araucanus e Tropocyclops prasinus) são abundantes nas zonas de superfície à noite, de manhã cedo e à tarde, enquanto, ao meio-dia, as abundâncias do zooplâncton são altas nas zonas de profundidade. Os resultados expostos corroboram as observações para outros lagos argentinos e da América do Norte, onde foram reportados esses padrões de migração diária em espécies crustáceas de zooplâncton por causa, principalmente, da exposição à radiação ultravioleta natural, enquanto, para lagos do hemisfério norte, a migração vertical se dá em razão do efeito combinado da radiação ultravioleta natural e exposição à predação.
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Zooplâncton , Lagos , Plâncton , Raios Ultravioleta , ChileRESUMO
Abstract The Neotropical free-living freshwater cyclopoid copepod Mesocyclops paranaensis Dussart & Frutos, 1986 was found in a small temporal pond in La Guajira, northern Colombia. Hitherto, it has been reported from Argentina, Paraguay, and Brazil. This is the first record of this species in Colombia, its northernmost finding in South America, and the fourth locality in which this species has been recorded from. Mesocyclops paranaensis can be distinguished from its closest congeners by a unique combination of the characters of the female, including: 1) leg 4 intercoxal sclerite with two large, acute projections; 2) P3, P4 intercoxal sclerite caudal surface lightly pilose; 3) seminal receptacle with narrow lateral arms and weakly convex anterior margin; 4) second antennary endopodite with seven setae, and insertion of antennary exopodal seta with adjacent spinules; 5)frontal surface of P1 basipodite ornamented with long spinules; 6) posterior margin of anal somite with continuous row of spinules; and 7) inner margin of caudal ramus hirsute. The Colombian population shows some subtle morphological differences with respect to previous reports.
Resumen El copépodo ciclopoide de agua dulce Mesocyclops paranaensis Dussart & Frutos, 1986 fue encontrado en un pequeño estanque temporal al norte de La Guajira. Hasta ahora, esta especie había sido registrada en Paraguay, Argentina y Brasil. Este es el primer registro de esta especie sudamericana en Colombia, su registro más septentrional en América del Sur, y la cuarta localidad en la que se registra. Mesocyclops paranaensis se puede distinguir de sus congéneres más cercanos por una combinación única de caracteres que incluyen: 1) esclerito intercoxal de la pata 4 con dos grandes proyecciones puntiagudas, 2) esclerito intercoxal de la pata 3 y pata 4 ligeramente piloso, 3) receptáculo seminal con brazos laterales estrechos y margen anterior débilmente convexo, 4)segundo segmento endopodal de la antena con siete setas, inserción de la seta exopodal de la antena con espínulas, 5) superficie frontal del basipodito de la pata 1 ornamentada con largas espínulas, 6) posterior margen del somita anal de la hembra con hileras continuas de espínulas y 7) margen interno de la rama caudal pilosa. Se proporciona una breve descripción de esta especie e ilustraciones de la población colombiana y se compara con su congénere más cercano. Los especímenes de Colombia muestran algunas diferencias morfológicas con respecto a los reportes previos acerca de esta especie.
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ABSTRACT Plankton samples obtained from the Ciénaga Grande de Santa Marta, an extensive estuarine system in northern Colombia, yielded adult male and female specimens of an undescribed halicyclopine cyclopid copepod of the genus Halicyclops. Cyclopid copepods are frequently found in freshwater and transitional habitats. Members of the subfamily Halicyclopinae are chiefly brackish water forms with a few freshwater species. The new species described herein is assignable to the group of species "F" of Halicyclops (sensu Pesce, 2018) with a 2333 exopodal spine formula. Currently, this group contains five species and one subspecies. Halicyclopsgutierrezi sp. n. can be distinguished from its known congeners by the absence of an anal operculum, the relative length of setae of the female and male P5, the relative length of the inner setae of P4EXP3, and details of the male antennule. This is the fifth species of Halicyclops recorded from Colombia and the first one of Halicyclops group "F" described from the Caribbean region. With the addition of H. gutierrezi sp. n., the number of species of the genus known from the Neotropics increased to 20. A key to the species of the genus recorded in Colombia is also provided.
RESUMEN Muestras de plancton obtenidas de la Ciénaga Grande de Santa Marta, un extenso sistema estuarino en el norte de Colombia, produjeron especímenes machos y hembras de una especie no descrita del género Halicyclops. Los copépodos de la familia Cyclopidae son dominantes en los hábitats de agua dulce y transicionales. Los miembros de la subfamilia Halicyclopinae son predominantemente de hábitats salobres, con algunas especies de agua dulce. La nueva especie aquí descrita es asignable al grupo de especies denominado "F" de Halicyclops (sensu Pesce, 2018) con una fórmula de espinas exopodales (P1-4) = 2333. Actualmente, este grupo contiene cinco especies y una subespecie. Halicyclops gutierrezi sp. n. puede distinguirse de sus congéneres conocidos por la ausencia de un verdadero opérculo anal, la longitud relativa de las setas de la P5 de la hembra y del macho, la longitud relativa de las setas internas de P4EXP3 y por detalles de la anténula del macho. Esta es la quinta especie de Halicyclops registrada en Colombia y la primera del grupo "F" de Halicyclops descrita en la cuenca del Caribe. Con la adición de H. gutierrezi sp. n., aumentó a 20 el número de especies del género que se conocen en la región Neotropical. Se proporciona una clave para la identificación de las especies del género registradas en Colombia.
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Introducción: Los tomoptéridos son poliquetos holopelágicos ampliamente distribuidos en todos los océanos, sin embargo, han sido pobremente estudiados, a pesar de sus importantes implicaciones en las redes tróficas como depredadores de varios grupos de animales de la comunidad del plancton, incluyendo huevos y larvas de peces. Objetivo: Describir la estructura de la comunidad de estos gusanos pelágicos en un área de surgencia en el Pacífico oriental centroamericano. Métodos: Las muestras de zooplancton fueron obtenidas durante la campaña oceanográfica "DOMO IV" organizada por la Universidad Nacional Autónoma de México en julio-agosto de 1982. Los poliquetos de la familia Tomopteridae fueron separados e identificados, aportando datos de su composición específica, abundancia y distribución. Resultados: Se determinaron cuatro especies del género Tomopteris siendo T. elegans y T. planktonis dominantes, T. nationalis constante y T. euchaeta rara. Tomopteris nationalis, T. elegans and T. euchaeta tienen afinidades tropical y subtropical, mientras que T. planktonis ha sido considerada como una especie cosmopolita. Tomopteris elegans presento la abundancia relativa mayor (62%) y T. euchaeta la menor (2.5). Conclusión: En general, T. elegans y T. planktonis mostraron un notable incremento en su abundancia relacionado con la región de la surgencia en el domo térmico de Costa Rica.
Introduction: The tomopterids are holopelagic polychaetes widely distributed in all oceans, nevertheless they have been poorly studied despite their important implications in the trophic webs, as predators of various groups of zooplankton, including eggs and fish larvae. Objective: To describe the structure of the community of these pelagic worms in an upwelling area in the Central American Pacific. Methods: The zooplankton samples were obtained during the oceanographic campaign DOMO IV organized by the Universidad Nacional Autónoma de Mexico, in July-August, 1982. The polychaetes of the Tomopteridae family were sorted out and identified providing data on their specific composition, abundance and distribution. Results: Four species of the genus Tomopteris were determined, being T. elegans and T. planktonis dominant, T. nationalis constant and T. euchaeta rare. T. nationalis, T. elegans and T. euchaeta have tropical and subtropical affinies, while T. planktonis have been considered as cosmopolitan species. T. elegans had the higher relative abundance (62%) and T. euchaeta the lower (2.5%). Conclusion: Overall, T. elegans and T. planktonis showed a notable rise in the abundance related to upwelling in the thermal dome of Costa Rica.
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El cadmio es un metal tóxico que produce deformaciones en el zooplancton y es considerado un peligro para el ambiente y la vida acuática. Por ello, utilizamos dos especies de zooplancton nativas de Quintana Roo, México para obtener datos sobre la toxicidad de cadmio, incluyendo la concentración umbral para alteraciones morfológicas observables y el porcentaje de organismos con alteraciones morfológicas en las concentraciones de exposición. Utilizamos el rotífero Philodina cf roseola y el oligoqueto Aeolosoma hemprichi, ya que ambos se alimentan del alga Nannochloropsis oculata. Seguidamente, ambas especies de animales fueron expuestas a un rango de concentración de cadmio de 0.05 (0.047 mg/l, concentración real) a 10.0 mg/l (9.398 mg/l, concentración real) durante 24 h. El CL50 para cadmio en P. cf roseola fue de 0.7 mg/l (0.65 mg/l, concentración real), mientras que en A. hemprichi fue de 3.38 mg/l (3.17 mg/l, concentración real). El cadmio a concentraciones de 0.5 mg/l (0.47 mg/l, concentración real) y exposición menor a 24 h, por un lado, indujo alteraciones morfológicas en la lorica de los rotíferos, deformaciones del pie y constricciones en la parte media del cuerpo. En oligoquetos, por otro lado, observamos daños en la epidermis. La concentración umbral donde las deformaciones aparecieron en rotíferos fue 0.3 mg/l (0.28 mg/l, concentración real) a las 24 h, mientras que en oligoquetos fue a 0.5 mg/l (0.47 mg/l concentración real) en 30 min. Concluimos que claramente el cadmio promueve alteraciones morfológicas en organismos acuáticos, debido a la exposición directa que se añade al medio de cultivo.
Cadmium is a toxic metal for zooplankton that produces deformations. It is also considered an environmental hazard to aquatic life. Since it has a significant effect in some marine organisms, we used two native zooplankton species from Quintana Roo, Mexico to obtain data regarding cadmium toxicity including the threshold concentration for observable morphological alterations and the percentage of organisms with morphological alterations at the exposure concentrations. We used the rotifer Philodina cf roseola and the oligochaeta Aeolosoma hemprichi, since both feed from the algae Nannochloropsis oculata. Both animals were exposed to a cadmium concentration range from 0.05 mg/l (0.047 mg/l, real concentration) to 10.0 mg/l (9.39 mg/l, real concentration) for 24 h. The LC50 for cadmium in P. cf roseola was 0.7 mg/l (0.65 mg/l, real concentration), whereas in A. hemprichi was 3.38 mg/l (3.17 mg/l, real concentration). The exposure of cadmium at 0.5 mg/l (0.47 mg/l, real concentration) for less than 24 h induced morphological alterations in the lorica of rotifers, foot deformations, and constriction in the middle part of the body. In oligochaetes, damage to the epidermis was noted. The threshold concentration where deformations appeared in rotifer was 0.3 mg/l at 24 h, while in oligochaeta was 0.5 mg/l (0.47 mg/l, real concentration) at 30 min. We concluded that cadmium promotes alterations in aquatic organisms due to direct exposure added to the culture medium.
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En los lagos tropicales, los cambios estacionales en la dinámica del plancton son mínimos e irregulares, ya que las condiciones climáticas son bastante estables durante todo el año, en la mayoría de los casos solamente estudios a largo plazo permiten observar patrones en la dinámica del plancton. El lago de Río Cuarto es un lago meromícto tipo maar localizado en las llanuras del norte de Costa Rica, en el pasado se han realizado estudios limnológicos no mayores a un año de muestreo, en este trabajo presentamos datos de la composición del fitoplancton y del zooplancton a lo largo de cuatro años, del 2013 al 2017, con el fin de analizar cambios en la comunidad del plancton en un periodo de tiempo mayor, asociados a variables ambientales. Para el fitoplancton se tomaron muestras subsuperficiales y se fijaron con lugol, y para el zooplancton se hicieron arrastres verticales de 20 m con una red con 64 µm de poro, que se preservaron con formalina y luego se pasaron a alcohol de 95 %. El fitoplancton incluyó 54 taxa, la mayoría fue Chlorophyta, seguidos por Cyanobacteria y Bacillariophyta. Las taxa más comunes fueron: Synechococcus spp., Aphanocapsa sp. Coenochloris fotii, Chlorella sp. y Discostella stelligera. La abundancia total del fitoplancton disminuyó de 2013 a 2017, principalmente debido a una disminución en las Cyanobacteria. El zooplancton estuvo compuesto por 14 taxa: 5 cladóceros, 4 copépodos, 1 díptero y 4 rotíferos. Los más abundantes fueron: Keratella americana, Brachionus falcatus, Eubosmina tubicen y Arctodiaptomus dorsalis. Se observó un cambio en la diversidad y abundancia del zooplancton, al principio (2013-2014) K. americana y E. tubicen se alternaron en dominancia, y luego (2015-2016) A. dorsalis, Diaphanosoma sp. y Ceriodaphnia sp. fueron dominantes, con un regreso de K. americana en el 2017. Los cambios observados en el periodo de estudio parecen estar relacionados con cambios en la condición del lago, pues la termoclina se hundió y el lago se volvió más trasparente durante el estudio. La abundancia, de rotíferos y del cladócero Eubosmina tubicen, disminuyó asociada a una disminución de Cyanobacterias. Esos cambios no siguieron un ciclo anual, más bien parecen cambios que ocurren a largo plazo, tal y como se ha propuesto en la literatura sobre lagos tropicales.
In tropical lakes, seasonal changes in plankton dynamics are minimal and irregular, since climatic conditions are fairly stable throughout the year, in most cases only long-term studies allow observing patterns in the dynamics of the plankton. Lake Río Cuarto is a maar-type meromic lake located in the plains of Northern Costa Rica, in the past there have been no limnological studies more than a year of sampling, in this work we present data on the composition of phytoplankton and zooplankton over four years, from 2013 to 2017, with the aim of analyzing changes in the plankton community in a longer period, associated with environmental variables. Phytoplankton was studied from subsurface samples, preserved in Lugol's solution and zooplankton from 20 m vertical hawls of a 64 µm mesh net, and preserved with formaline and later transferred to 95 % ethanol. Phytoplankton composition included 54 taxa, most of them were Chlorophyta, followed by Cyanobacteria and Bacillariophyta. The most abundant were: Synechococcus spp., Aphanocapsa sp. Coenochloris fotii, Chlorella sp. and Discostella stelligera. Total phytoplankton decreased from 2013 to 2017, mainly due to a decrease in Cyanobacteria. Zooplankton comprised 14 taxa, 5 cladocerans, 4 copepods, 1 diptera and 4 rotifers. The most abundant were: Keratella americana, Brachionus falcatus, Eubosmina tubicen and Arctodiaptomus dorsalis. There was a substitution of dominant species through time, at first (2013-2014) K. americana and E. tubicen alternated in dominance, and later (2015-2016), A. dorsalis, Diaphanosoma sp. and Ceridaphnia sp. became dominant, with a return of K. americana by 2017. The changes that occurred during the time of the study seem to be related to changes in the conditions of the lake, since its thermocline deepened with time and became more transparent. The abundance, of rotifers and Eubosmina tubicen, decreased associated to a decrease of Cyanobacteria. Those changes were not cyclical on an annual basis, but seemed to occur more on a long-term basis, as has been recognized earlier in the literature about tropical lakes.
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Introducción: Desde un punto de vista global, los poliquetos que habitan en la comunidad pelágica han sido poco estudiados, aunque son un eslabón importante en las cadenas alimentarias de los ecosistemas marinos. Objetivo: Este trabajo contribuye al conocimiento de esta importante comunidad, analizando la riqueza y la densidad de los poliquetos. Métodos: Las muestras de plancton se tomaron en 17 localidades durante mayo y diciembre de 2013 en el área de estudio, mediante arrastres superficiales en una embarcación con un motor fuera de borda. Utilizamos una red con un diámetro de boca de 0.3 m, una longitud de 1.30 m y una abertura de malla de 0.3 mm. De cada muestra recolectada, los poliquetos se separaron y determinaron al nivel taxonómico más bajo posible. Resultados: Cuantificamos un total de 1873 individuos, con una variación importante en la densidad relativa, ya que en mayo se registraron 7 952.0 ind/100m3, mientras que en diciembre solo hubo 882.1 ind/100m3. Se analizaron las diferencias en la composición y densidad de los poliquetos determinados, de los cuales la proporción más alta pertenece a las formas larvales de las poblaciones bentónicas (meroplancton) y la más baja a los organismos del holoplancton. Durante los dos periodos de estudio se observaron trece familias, de las cuales, Sabellariidae, Spionidae, Chaetopteridae, Magelonidae, Iospilidae y Typhloscolecidae fueron comunes en ambos periodos, mientras que Aphroditidae, Syllidae, Phyllodocidae y Alciopidae fueron exclusivas de mayo y Serpullidae, Sabellidae y Lopadorhynchidae solo se encontraron en diciembre. Conclusiones: Es importante señalar que las variaciones observadas proporcionan valiosa información sobre los ciclos de vida y los aspectos biogeográficos de los poliquetos en el área de estudio.
Introduction: From a global point of view, polychaetes that inhabit in the pelagic community have been little studied, although they are an important link in the food chains of marine ecosystems. Objective: To analyze the local richness and density of polychaetes. Methods: Plankton samples were taken in 17 localities during May and December 2013, through surface trawls in a barge with an outboard motor. We used a net with 0.3 m mouth diameter, 1.30 m long and a 0.3 mm aperture mesh. From each collected sample, polychaetes were separated and determined at the lowest possible taxonomic level. Results: We collected a total of 1 873 individuals, with an important variation in relative density, since in May 7 952.0 ind/100m3 were recorded, while in December there were only 882.1 ind/100m3. The differences in the composition and density of the determined polychaetes, were analyzed, of which the highest proportion belongs to the larval forms of the benthic (meroplankton) populations, and the lowest proportion to holoplankton organisms. During the two periods of study were observed thirteen families, from which Sabellariidae, Spionidae, Chaetopteridae, Magelonidae, Iospilidae and Typhloscolecidae were common in both periods, while Aphroditidae, Syllidae, Phyllodocidae and Alciopidae were observed only in May, and Serpulidae, Sabellidae and Lopadorhynchidae were observed only in December. Conclusions: It is important to point out that the observed variations provide valuable information about the life cycles and the biogeographic aspects of the polychaetes in the study area.
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RESUMEN Objetivo. Describir las comunidades planctónicas y bacterianas asociadas al cultivo de bocachico Prochilodus magdalenae con tecnología biofloc (BFT). Materiales y métodos. En nueve tanques rectangulares de concreto con volumen útil de 6.0 m3, se sembraron alevinos de bocachico con peso promedio de 1.6±0.2 g, a tres densidades 5 (T1), 10 (T2) y 20 (T3) peces/m3 con BFT, durante 120 días de cultivo. La identificación y cuantificación de los microorganismos se realizó cada ocho días, en una muestra de 250 ml de agua por tanque, mediante análisis de alícuotas en cámaras Sedgwick-Rafter y/o Neubauer bajo microscopio a 10x y 40x. Los días 15, 45 y 90 del cultivo se caracterizaron las comunidades bacterianas tomando una muestra de 2 g de floc en 90 ml de solución salina estéril y sometidas a pruebas microbiológicas convencionales. Resultados. Se identificarem cinco grupos planctónicos (microalgas, rotíferos, cladóceros, copépodos y protistas con predominancia de ciliados) con mayor cantidad de rotíferos y protistas en los cultivos con menor densidad (T1 y T2); y la mayor afluencia de microorganismos osciló entre 174.9±21.4 ind/ml (T1) y 125.6±16.1 ind/ml (T2). En el grupo de bacterias fue posible identificar 10 cepas: Escherichia coli, Enterobacter sp., Klebsiella sp., Salmonella sp. (Enterobacteriaceae) Bacillus subtilis, Bacillus sp, Lactobacillus sp, Pseduodomonas sp (Vibrionaceae), Micrococcus sp, Staphylococcus sp (Cocos gram+). Conclusiones. La composición del plancton fue similar en todos los tratamientos, con rotífero y protistas como los más abundantes; la mayor proporción de bacterias fueron Enterobacterias y Heterotróficas.
ABSTRACT Objective. To describe the planktonic communities and bacteria associated with the bocachico Prochilodus magdalenae fish culture with biofloc technology (BFT). Materials and methods. Bocachico fingerlings, with an average weight of 1.6±0.2 g, were stocked at three densities, i.e., 5 (T1), 10 (T2) and 20 (T3) fish/m3, with BFT in nine rectangular, 6.0 m3 concrete tanks for 120 days of culture. Identification and quantification of the microorganisms was performed every eight days in a sample of 250 ml of water per tank by analyzing aliquots on a Sedgwick-Rafter and/or in Neubauer chambers on a microscope at 10x and 40x magnification. On days 15, 45, and 90 of the fish culture, the bacterial communities were characterized by taking 2 g samples of floc and adding them to 90 ml of sterile saline solution, then subjecting them to conventional microbiological tests. Results. Five planktonic groups (microalgae, rotifers, cladocerans, copepods, and protists with ciliates predominating) with more rotifers and protists in the fish cultures at lower density (T1 and T2) were identified, and the largest amount of microorganisms oscillated between 174.9±21.4 ind/ml (T1) and 125.6±16.1 ind/ml (T2). It was possible to identify ten bacterial strains: Escherichia coli, Enterobacter sp., Klebsiella sp., Salmonella sp. (Enterobacteriaceae), Bacillus subtilis, Bacillus sp., Lactobacillus sp., Pseudomonas sp. (Vibrionaceae), Micrococcus sp., and Staphylococcus sp. (Coccus Gram+). Conclusions. The composition of plankton was similar in all treatments, with rotifers and protists being the most abundant; the bacteria showed a higher proportion of enterobacteria and heterotrophs.
Assuntos
Animais , Zooplâncton , Aquicultura , BactériasRESUMO
Abstract Copepods are an important planktonic group, and account for most of the total biomass and species diversity in pelagic marine ecosystems. Seasonal variability of the community structure of copepods in the Eastern tropical Pacific off central Mexico was studied during three distinct hydrodynamic periods in 2010 using statistical and multivariate analyses. The survey period included the second half of the 2009-2010 El Niño (January), the neutral transition period (May-June), and the first half of the 2010-2011 La Niña (October). Seventy-eight copepod species were identified; richness ranged from 11 to 47 species per station, with seasonal averages from 25 species in May to 35 species in January. Cluster analysis indicated that there were four principal groups present across the surveyed periods, defined by January (El Niño), October (La Niña), May offshore stations, and May upwelling stations (cyclonic eddy and coastal stations). There were no significant differences in abundance, but the January (El Niño) cluster was most diverse with 32 species, May offshore and October (La Niña) clusters each had 25 species, and the May upwelling was the least diverse cluster with 18 species. Mesoscale processes were strongest during May, which was the only period with a significant inshore-offshore gradient of species richness and diversity. Canonical correspondence analysis (CCA) revealed that variability was primarily driven by subsurface (75-200 m) ammonium, and surface (0-50 m) temperature, nitrates+nitrites, salinity and phosphorus. Copepodites and adults of the primarily herbivorous Eucalanidae dominated the stations of the upwelling cluster, while copepodites and adults of the carnivorous Euchaetidae dominated the January (El Niño) station cluster. The higher Chl a levels during the less productive (reduced upwelling) El Niño period were probably due to reduced grazing activities and increased ammonium availability through increased zooplankton metabolism. The horizontal distribution of copepods in the Eastern Tropical Pacific off Mexico appears to be principally defined by mesoscale eddy processes (offshore) and upwelling (coastal). These mesoscale processes were affected by El Niño - La Niña transitions, which subsequently disrupted the inshore-offshore gradient and in the case of El Niño likely caused reductions in copepod abundance across the entire region which persisted for the entire study period, and possibly longer.(AU)
Resumen Los copépodos son un importante grupo planctónico y representan la mayor parte de la biomasa total y la diversidad de especies en los ecosistemas marinos pelágicos. La variabilidad estacional de la estructura de la comunidad de copépodos se analizó en el Pacífico central mexicano durante tres períodos hidrodinámicos durante el 2010, mediante análisis estadísticos y multivariados. El período de estudio incluyó la segunda mitad del Niño 2009-2010 (enero), el período de transicional (mayo) y la primera mitad del La Niña 2010-2011 (octubre). Setenta y ocho especies de copépodos fueron identificadas; la riqueza varió de 11 a 47 especies por estación, con promedios estacionales de 25 especies en mayo a 35 especies en enero. El análisis de clúster indicó la presencia de cuatro grupos principales en los períodos estudiados: enero (El Niño), octubre (La Niña), un grupo de estaciones oceánicas en mayo, y un grupo de estaciones de afloramientos en mayo (remolino ciclónico y estaciones costeras). No hubo diferencias significativas en la abundancia entre grupos, pero el grupo de enero (El Niño) fue más diverso con 32 especies. Los grupos de mayo (oceánico) y octubre (La Niña) tenían 25 especies cada uno, y el grupo de mayo (afloramientos) fue el menos diverso con 18 especies. Los procesos de mesoescala fueron más intensos durante mayo, que fue el único período con un gradiente significativo costeroocéano de riqueza de especies y diversidad. El análisis de correspondencias canónicas explicó que la variabilidad se debe principalmente a la concentración de amonio en la capa profunda (75-200), y la temperatura, nitratos + nitritos, salinidad y fósforo presente en la capa superficial (0-50 m) de la columna de agua. Los copepoditos y adultos herbívoros de la familia Eucalanidae, dominaron las estaciones de surgencia, mientras que los copepoditos y adultos carnívoros de Euchaetidae dominaron las estaciones de enero (El Niño). Las concentraciones más altas de Clorofila a durante El Niño, que fue el periodo menos productivo (surgencia reducida), se deben probablemente a la reducción de actividades de pastoreo. La distribución horizontal de copépodos en el Pacífico central mexicano parece estar definida principalmente por la influencia de remolinos de mesoescala (mar adentro) y surgencias (costera). Estos procesos oceanográficos fueron afectados por la transición de El Niño a La Niña, que posteriormente interrumpieron el gradiente costero-oceánico y en el caso de El Niño probablemente causó una disminución en la abundancia de copépodos en toda la región durante todo el período de estudio, que posiblemente persistió en los meses posteriores.(AU)
Assuntos
Estações do Ano , Zooplâncton , Turbulência de Fluidos , Copépodes , El Niño Oscilação Sul/efeitos adversos , MéxicoRESUMO
Abstract Most studies on mechanisms regulating fish larvae processes have focused on assessing the isolated effects of food distribution and feeding behavior. However, in natural ecosystems, fish larvae may strongly interact with zooplankton organisms in an array of complex, direct and indirect interdependencies. This study analyzed the spatial distribution, diet and feeding behavior of early stages of Hypophthalmus edentatus and Plagioscion squamosissimus, two fish species co-occurring in an isolated floodplain lake, during the light-dark cycle. Larvae fed more actively during dark periods (dusk and night) when they migrated toward the surface of the lake, and remained on the bottom and fed less during light periods (day and dawn). Cladocerans represented the most frequent prey in the diet of H. edentatus larvae. In turn, P. squamosissimus larvae initially preferred cladocerans and, as they developed, included calanoid copepods in the diet. Significant differences were detected in the frequencies of food items consumed during larval development, which could be related to a better ability of the most developed stages to explore the environment in search of other prey.
Resumo A maioria dos estudos de mecanismos que regulam os processos de larvas de peixes se concentra na avaliação dos efeitos isolados da distribuição do alimento e do comportamento alimentar. No entanto, em ecossistemas naturais, as larvas de peixes podem interagir fortemente com os organismos do zooplâncton em uma série de interdependências complexas, diretas e indiretas. Este estudo analisou a distribuição espacial, dieta e comportamento alimentar dos estágios iniciais de vida de Hypophthalmus edentatus e Plagioscion squamosissimus, duas espécies de peixes coexistentes em uma lagoa isolada de planície de inundação, durante o ciclo claro-escuro. As larvas se alimentaram mais ativamente durante os períodos escuros (crepúsculo e noite) quando ascenderam em direção à superfície da lagoa, enquanto durante os períodos luminosos (dia e amanhecer) permaneceram no fundo e pouco se alimentaram. Os cladóceros foram as presas mais frequentes na dieta de larvas de H. edentatus. Por sua vez, larvas de P. squamosissimus inicialmente preferiram cladóceros, e a medida que se desenvolveram incluíram copépodes calanóides na dieta. Diferenças significativas foram detectadas nas frequências dos itens alimentares consumidos durante o desenvolvimento larval, o que poderia estar relacionado a uma melhor capacidade dos estágios mais desenvolvidos em explorar o ambiente na busca por outras presas.
Assuntos
Animais , Ritmo Circadiano/fisiologia , Comportamento Alimentar/fisiologia , Peixes/fisiologia , Larva/fisiologia , Brasil , Lagos , Densidade Demográfica , Fotoperíodo , Ecossistema , DietaRESUMO
We aimed to perform the first survey of testate amoebae community composition in Lake Monte Alegre at São Paulo state, and contribute to mitigate the taxonomic impediment regarding thediversity of testate amoebae in Brazil. Samplings were performed in 20 sampling sites within the lake, inthe limnetic and littoral regions in April 2015, using a 58 μm-meshplankton net. We identified 20 taxa oftestate amoebae belonging to four families: Arcellidae (8 taxa), Centropyxidae (4 taxa), Difflugiidae (7 taxa) and Lesquereusiidae (2 taxa). The littoral region showed the highest number of taxa (n = 20), whereas inthe limnetic region 11 taxa were registered. Therefore, our results evidenced the importance of testateamoebae in aquatic systems, and that further research, taxonomic and/or ecological, in those environmentsshould include these organisms in their investigation. Moreover, we suggest that future research with greater sampling effort is necessary to expand the identification of possible cryptic species in this environment.
O objetivo deste estudo foi realizar o primeiro levantamento da composição da comunidade de amebas testáceas no lago Monte Alegre no Estado de São Paulo e, assim, contribuir para mitigar oimpedimento taxonômico relacionado à diversidade de amebas testáceas no Brasil. As amostragens foramrealizadas em 20 pontos do lago, nas regiões limnética e litorânea, no mês de abril de 2015, com rede deplâncton de 58 μm de abertura de malha. Foram identificados 20 táxons de amebas testáceas, divididos emquatro famílias: Arcellidae (8 táxons), Centropyxidae (4 táxons), Difflugiidae (7 táxons) e Lesquereusiidae(2 táxons). A região litorânea apresentou o maior número de táxons (n = 20), enquanto que na regiãolimnética foram registrados 11 táxons. Diante disso, é possível indicar que os nossos resultados evidenciama importância das amebas testáceas nos sistemas aquáticos e que novos estudos, taxonômicos e/ou ecológicos, nesses ambientes devem incluir estes organismos em suas investigações. Além disso, sugeremsefuturos estudos com maior esforço amostral para ampliar a identificação de possíveis espécies crípticas noambiente.
Assuntos
Amoeba/classificação , Amoeba/química , Classificação , Zooplâncton/virologiaRESUMO
Abstract Central Argentina has numerous saline lakes sustained by groundwater sources and rainfall. These lakes are temporary and experience significant changes in water level and salinity, depending on wet and dry climate cycles. This study aims to investigate the scarcely known dynamics of environmental and zooplankton parameters during the drying phase of one of these lakes. Monthly samples were taken from December 2 012 to July 2 013 in the Ojo de Agua Uriburu lake, previous to its drying. At the beginning of the study, the lake's depth was 0.7 m and its salinity was 16.65 g L-1, later, in July, its depth decreased to 0.06 m and its salinity increased to 92.9 g L-1. Zooplankton species richness was low (three crustaceans and three rotifers), with Boeckella poopoensis and Moina eugeniae dominating in the system. Maximum density and biomass were attained by the two dominant species in April (318.5 ind L-1 and 3 029.1 µg L-1 dry weight; and 242.4 ind L-1 and 1 530.4 µg L-1 dry weight, for B. poopoensis and M. eugeniae, respectively), and no correlation was found between these parameters and salinity. Maximum average body lengths for both species were observed in the last months of sampling (M. eugeniae: 1 020 ± 84.2 µm and B. poopoensis: 1 348.8 ± 89.0 µm). At this point of the study, neither juvenile nor larval stages were found. The increase in average body size is, arguably, the result of increased salinity in the system through a negative effect on reproduction. Because this lake reached hypersalinity, its ecological dynamics are unique among those of other temporary, saline lakes that dried in central Argentina. Similar studies on other temporary ecosystems are needed to increase the information on these little known ecological aspects.
Resumen Argentina central tiene numerosos lagos salinos alimentados por fuentes de agua subterránea y agua de lluvia. Estos lagos son temporales y experimentan cambios significativos en el nivel de agua y la salinidad, de acuerdo con los ciclos climáticos de sequía y humedad. Este estudio pretende investigar las poco conocidas dinámicas del zooplancton y de los parámetros ambientales durante la fase de desecación de uno de estos lagos. Se tomaron muestras mensuales desde Diciembre de 2012 hasta Julio de 2013 en el lago "Ojo de Agua Uriburu", antes de su desecación. Al principio del estudio, la profundidad del lago fue de 0.7 m y su salinidad fue de 16.65 g L-1. Posteriormente, en Julio, su profundidad decreció a 0.06 m y su salinidad aumentó a 92.9 gL-1. La riqueza de especies de zooplancton fue baja (3 crustáceos y 3 rotíferos), con Boeckella poopoensis y Moina eugeniae dominando el sistema. Estas dos especies alcanzaron la máxima densidad y biomasa en Abril (318.5 ind L-1 y 3 029.1 µg L-1 en peso seco; 242.4 ind L-1 y 1 530.4 µg L-1 en peso seco para B. poopoensis y M. eµgeniae, respectivamente). No se encontró correlación ente estos dos parámetros y la salinidad. Las máximas longitudes corporales promedio para ambas especies se obtuvieron en los últimos meses de muestreo (M. eµgeniae: 1 020 µm ± 84.2 y B. poopoensis: 1 348.8 µg ± 89.0 µm). En este punto del estudio, no se encontraron estados larvales ni juveniles. El incremento en tamaño corporal es, posiblemente, el resultado del efecto en la reproducción causado por el incremento en la salinidad del sistema. Dado que el lago alcanzó un estado de hipersalinidad, sus dinámicas ecológicas son únicas en el conjunto de lagos temporales y salinos que se secan en Argentina Central. Se requieren estudios similares en otros ecosistemas temporales para aumentar la información sobre estos aspectos ecológicos poco conocidos.
Resumo. No centro da Argentina há inúmeros lagos salinos que são alimentados por aportes freáticos e precipitações. Estes lagos são temporários e sofrem alterações significativas do nível de água e salinidade, relacionados com ciclos climáticos úmidos e secos. O objetivo deste estudo foi investigar a dinâmica pouco conhecida dos parâmetros ambientais e do zooplâncton durante a fase de secagem de um desses lagos. As amostras foram coletadas mensalmente entre dezembro de 2012 a julho de 2013 no lago "Ojo de Agua Uriburu", antes da secagem do mesmo. No início do estudo, a profundidade do lago foi de 0.7 m e a salinidade foi de 16.65 g L-1, mais tarde, em julho, sua profundidade diminuiu para 0.06 m enquanto a salinidade aumentou até 92.9 g L-1. A riqueza de espécies do zooplâncton foi baixa (três crustáceos e três rotíferos), com predomínio de Boeckella poopoensis Marsh, 1906 e Moina eugeniae Olivier, 1954 no sistema. A densidade máxima e biomassa foram atingidas pelas duas espécies dominantes em abril (318.5 ind L-1 e 3 029.1 µg L-1 de peso seco, e 242.4 ind L-1 e 1 530.4 µg L-1 de peso seco, para B. poopoensis e M. eugeniae, respectivamente), e não foi encontrada correlação entre ambos os parâmetros e a salinidade. O comprimento médio máximo do corpo para ambas as espécies foi observado nos últimos meses de amostragem (M. eugeniae: 1 020 µm ± 84.2 e B. poopoensis: 1 348.8 µm ± 89.0). Neste ponto do estudo, não foram evidenciados estágios juvenis nem larvais. O aumento do tamanho médio do corpo é, possivelmente, devido a um efeito negativo da salinidade na reprodução. Dado que este lago atingiu a hipersalinidade, sua dinâmica ecológica é única entre as dinâmicas dos outros lagos salinos temporários que secaram no centro da Argentina. Estudos semelhantes em outros ecossistemas temporários são necessários para aumentar a informação sobre estes aspectos ecológicos pouco conhecidos.
Assuntos
Zooplâncton , Lagos/análiseRESUMO
Se analizó la composición y abundancia del zooplancton de la laguna El Morro en la isla de Margarita, Venezuela, durante el periodo de surgencia (marzo-mayo 2011) y de relajación (junio-agosto 2011). Las muestras fueron recolectadas en 6 estaciones de las diferentes zonas de la laguna. Se realizaron calados con una red de plancton de 333 µm durante 10 minutos. Se midió in situ la temperatura, salinidad y oxígeno disuelto, además de nutrientes. Se registraron valores medios de temperatura de 29.7 ºC, salinidad de 36 ups, oxígeno disuelto de 5.9 mg.L-1. La concentración de nutrientes fue baja (medias de 0.12; 0.04; 0.03 mg.L-1 para nitrato, nitrito y fosfato, respectivamente). Se detectaron diferencias significativas temporales con mayores registros en la temporada de relajación, mientras que espacialmente no mostró diferencias, a pesar que en las estaciones internas (Est. 4,5,6) se obtuvo mayor abundancia. Se identificaron quince grupos zooplanctónicos, determinándose nueve especies del grupo Copepoda, dos de Cladocera, una de Decapoda, Tunicada y Rotifera y diferentes formas larvarias de distintos taxa. Las larvas de crustáceos presentaron la abundancia media y relativa más alta (47738 ind.m-3 y 46.83%, respectivamente), seguido del copépodo Oithona nana (31740 ind.m-3 y 25.94%, respectivamente) y Paracalanus quasimodo (12958 ind.m-3 y 8.47%, respectivamente). Esta laguna involucra la estacionalidad surgencia-relajación como un efecto importante en la distribución y abundancia del zooplancton.
The composition and abundance of the zooplankton of El Morro lagoon on the island of Margarita, Venezuela, during the upwelling period (March-May 2011) and relaxation (June-August 2011) were analyzed. Samples were collected at 6 stations in different areas of the lagoon. Sampling was performed with a 333 μm plankton net for 10 minutes. Water Temperature, salinity and dissolved oxygen were measured in situ, in addition to nutrients. Average water temperature values of 29.7 °C, a salinity of 36 ups, and dissolved oxygen of 5.9 mg.L-1 were found. The concentration of nutrients was low (averages of 0.12, 0.04, 0.03 mg.L-1 for nitrate, nitrite and phosphate, respectively). Significant seasonal differences were detected with greater records in the relaxation season, whereas spatially did not show differences, although in the internal stations a greater abundance was recorded. Fifteen zooplankton groups were identified, identifying nine species of Copepoda, two of Cladocera, one of Decapoda, Tunicada and Rotifera and different larval forms of different taxa. Crustacean larvae showed the highest average and relative abundance (47738 ind.m-3 y 46.83%, respectively), followed by copepod O. nana (31740 ind.m-3 and 25.94%, respectively) and P. quasimodo (12958 ind.m-3 and 8.47%, respectively). This lagoon involves the emergence-relaxation seasonality as an important effect on the distribution and abundance of zooplankton.
RESUMO
Resumen: Los cambios en la composición y abundancia de las especies de copépodos a escala espacial y temporal, ayudan a comprender el funcionamiento de los ecosistemas y de cómo la dinámica oceanográfica afecta su variación. Debido a los pocos estudios de este grupo en zonas costeras del Pacífico colombiano, se estudiaron los cambios en la distribución espacial y temporal de la comunidad de copépodos de Bahía Cupica, durante diciembre 2012 y febrero 2013. Se realizaron arrastres oblicuos en 22 estaciones a lo largo de seis transectos perpendiculares a línea de costa, durante dos periodos oceanográficos contrastantes, usando una red bongo (30 cm de diámetro, 2.1 m de largo, con mallas de 250 µm y 500 µm) equipada con un flujómetro. Los resultados mostraron cambios significativos en las condiciones oceanográficas y en el patrón de circulación superficial. Se identificaron en total 52 especies de copépodos de las cuales 35 son nuevos registros para el Pacífico colombiano. La mayor abundancia se presentó durante febrero 2013 (28 604 ind. 100 m-3), con una prevalencia de especies de pequeña talla en los dos periodos. Durante diciembre 2012 se registró una mayor abundancia de especies del orden Poecilostomatoida (58.2 %), y durante febrero 2013 por especies del orden Calanoida (69.5 %). Se identificaron cinco agrupaciones significativas con diferente estructura y composición de especies, tres en diciembre 2012, y dos durante febrero 2013, dividiendo la bahía en diferentes zonas. La estructura del ensamblaje de copépodos presentó una correlación positiva con la temperatura en ambos periodos, siendo mayor durante diciembre 2012. Los resultados sugieren que la zona nerítica del norte del Pacífico colombiano se ve modulada por procesos de surgencia, el patrón de circulación superficial local y la descarga de agua continental de la región, lo que determina la estructura y composición del ensamblaje de copépodos, además de cambios significativos en la abundancia de las especies. Los resultados son útiles para entender la estructura de la comunidad de copépodos, y los estudios futuros deberían intentar examinar otras variables (e.g. el efecto de la disponibilidad de alimento y la concentración de oxígeno disuelto) para mejorar el entendimiento de la estructura de copépodos en la región costera del Pacífico colombiano.
Abstract: The study of changes in abundance and composition of copepod species, at different temporal and spatial scales, help to understand the ecosystems function and how the oceanographic dynamics affects their variability and other resources abundances. Since very few studies have been developed on this group in Colombian Pacific coastal areas, the purpose of this study was to assess the spatial and temporal changes in the copepods community distribution at Cupica Bay, between December 2012 and February 2013. For this, oblique plankton hauls were performed along six transects perpendicular to the coast, in 22 stations, using a Bongo Net (30 cm diameter, 2.1 m large, with mesh size 250 µm and 500 µm) equipped with a flowmeter, during two contrasting oceanographic periods. The results showed significant changes in oceanographic conditions and superficial circulation patterns. Fifty two (52) copepods species were identified, from which thirty five (35) were new records for the Colombian Pacific. The biggest copepod abundance was recorded in February 2013 (28 604 ind. 100 m-3), and small copepods species were the most dominant. During December 2012, species of the order Poecilostomatida were the most abundant (58.2), but during February were the species of the order Calanoida (69.5 %). The community structure and species composition was characterized by five significant groups, three groups during December 2012 and two during February 2013, dividing the bay in different zones. A positive correlation between temperature and copepods assemblages was evident during both periods, but stronger during December 2012. The results suggested that community structure and species composition of resident copepods in North Colombian Pacific neritic zones, are modelled by the intensity of upwelling, superficial local pattern circulation, and continental freshwater discharges in the region. The results are helpful to understand the copepods community structure, and the future studies should attempt to examine other variables (e.g. effect of food available and oxygen concentration dissolved) to improve understanding of copepods structure in the Pacific coast region of Colombia. Rev. Biol. Trop. 65 (3): 1046-1061. Epub 2017 September 01.
RESUMO
Abstract The Llanquihue lake is included in the called Araucanian or Nord Patagonian lakes located between 38-41° S. These lakes are characterized by their oligo-mesotrophic status due to human intervention which takes to the increase in nutrients inputs from industries and towns. Effects on zooplankton assemblages are observed with marked increase of daphnids abundance. The aim of the present study is to analyze the trophic status and zooplankton relative abundance in different bays of Llanquihue lake. It was found direct associations between chlorophyll a with daphnids percentage, total dissolved nitrogen with reactive soluble phosphorus nitrogen/phosphorus molar radio with cyclopoids percentage, and an inverse relation between daphnids and calanoids percentages. The occurrence of three kinds of microcrustacean assemblages and environmental conditions was evidenced: the first one with high calanoids percentage, low species number and low chlorophyll and nutrients concentration, a second with moderate chlorophyll and nutrients concentration and moderate daphnids percentage; high species number and a third site with high chlorophyll and nutrients concentration, high daphnids percentage and high species number. Daphnids increase under mesotrophic status, agree with similar results observed for southern Argentinean and New Zealand lakes.
Resumo O lago Llanquihue está incluído nos chamados lagos araucana ou Nord Patagônia localizado entre 38-41° S. Estes lagos são caracterizados pela condicao oligo-mesotrofica debido a intervencao humana, com aumento da carga de nutrientes provenientes de industrias y areas urbanas com efeitos sobre as assembleias zooplantonicas sao observadas, com aumento acentuado de dafnideos. O objetivo do presente estudo é analisar o estado trófico a abundancia relative do zooplancton em diferentes compartimentos do lago Llanquihue. Foram encontradas associações diretas entre clorofila a com percentual de dafinídeos, nitrogênio total dissolvido com fósforo solúvel reativo molares razao molar nitrogênio / fósforo com percentual de ciclopóides, e uma relação inversa entre percentuais de dafinídeos e calanóides porcentagens. A ocorrência de três tipos de assembleias de microcrustáceos e as condições ambientais fora: a primeira com alta porcentais de calanóides, baixo número de espécies e baixa clorofila e a nutrientes, uma segunda com concentracoes moderadas de clorofila e nutrientes percentual moderado de daphnideos e alto número de espécies; e uma terceiro local com alta concentração de clorofila e nutrientes, alta abundância dafinídeos e número elevado de espécies. Resultados similares com aumento de dafnideos em condicoes mesotroficas também foram observados para lagos da Argentina e Nova Zelândia do sul.
Assuntos
Animais , Plâncton/isolamento & purificação , Lagos , Baías , Crustáceos , Fósforo/análise , Chile , Clorofila , Monitoramento Ambiental , Clorofila A , Nitrogênio/análiseRESUMO
Abstract Predator-prey interactions involving an aquatic insect and zooplanktonic prey of different sizes were investigated to quantify prey mortality exposed to predators. Laboratory experiments were undertaken with the young and adult gerrid Rheumatobates crassifemur to test predation and size selectivity on the cladocerans Daphnia gessneri, Ceriodaphnia richardi, and Bosmina tubicen. Population fluctuations and spatial distribution of the gerrid were also evaluated in a small and shallow Brazilian lake throughout 12 months in fortnightly samples. The insects were more abundant in the littoral (mean density 7.0 ± 1.2 ind.m-2) compared to the limnetic zone. The period with the highest densities was late January to June, in both zones. Predation by young instars on Daphnia and Ceriodaphnia was significant (mean ingestion rate of 1.3 ± 0.1 D. gessneri and 0.7 ± 0.1 C. richardi per predator per hour). Adult insect fed only the large-sized prey (mean ingestion rate of 1.0 ± 0.1 D. gessneri per predator per hour). Young gerrids have greater potential to prey on cladocerans than adults, and size selectivity occurred for both predators. Preference of adults by the larger prey is probably related to difficulties in manipulating smaller planktonic prey, such as Ceriodaphnia. Due to higher densities of insects in the littoral, higher predation on zooplankton in this zone is expected. This study does contribute to a better understanding of trophic interactions in tropical shallow lakes and is the first to investigate predation of a gerrid on cladocerans in laboratory experiments.
Resumo Foram investigadas as interações predador-presa, envolvendo inseto aquático e presas zooplanctônicas de diferentes tamanhos para quantificar a mortalidade das presas expostas a predadores. Experimentos de laboratório foram realizados com jovens e adultos do gerrídeo Rheumatobates crassifemur para testar a predação e a seletividade por tamanho das espécies de cladóceros Daphnia gessneri, Ceriodaphnia richardi e Bosmina tubicen. Flutuações populacionais e a distribuição espacial do gerrídeo também foram avaliadas em um lago brasileiro pequeno e raso durante 12 meses em amostras quinzenais. Os insetos foram mais abundantes no litoral (densidade média 7,0 ± 1,2 ind.m-2) em comparação com a zona limnética. Maiores densidades ocorreram de fim de janeiro a junho, em ambas as zonas. A predação dos jovens foi significativa sobre Daphnia e Ceriodaphnia (taxa de ingestão média 1,3 ± 0,1 D. gessneri and 0,7 ± 0,1 C. richardi por predador por hora). Adultos predaram somente a presa maior (taxa de ingestão média 1,0 ± 0,1 D. gessneri por predador por hora). Gerrídeos jovens têm um maior potencial para predar cladóceros que os adultos, e seletividade por tamanho ocorreu para ambos. A preferência dos adultos somente pela presa maior provavelmente está relacionada à dificuldade em manipular pequenas presas planctônicas como Ceriodaphnia. Devido às maiores densidades de insetos no litoral, é esperada maior predação sobre o zooplâncton nesta zona. Este estudo contribui para uma melhor compreensão sobre interações tróficas em lagos tropicais rasos e é o primeiro a investigar a predação de um gerrídeo sobre cladóceros em experimentos de laboratório.
