Trends in freshwater microcrustaceans studies in Brazil between 1990 and 2014 / Tendências nos estudos de microcrustáceos de água doce no Brasil entre 1990 e 2014

Abstract This study presents a review of scientiometric data about freshwater microcrustaceans (Copepoda, Ostracoda, Branchiopoda: Cladocera, Anostraca, Notostraca and Conchostraca) in Brazil from 1990-2014. This review is based on 179 papers published across four databases, using the following keywords in the search: microcrustaceans, Copepoda, Cyclopoida, Calanoida, Harpacticoida, Ergasilidae, Daphniidae, Moinidae, Cladocera, Ostracoda, Conchostraca, zooplankton, reservoir, river, ponds, reservoirs, wetlands, caves, lakes, limnology, ecology, aquatic, taxonomy, systematics, morphology and biogeography. No studies were identified that addressed freshwater microcrustaceans in four (Amapá, Roraima, Alagoas and Espírito Santo) of the 27 Brazilian Federative States. Forty-five percent of the included studies were concentrated within three of the most populous states (São Paulo, Minas Gerais and Paraná), which also have a long tradition of limnological study. The included studies mostly addressed reservoirs for hydropower generation (22%), multiple environments (22%), rivers (14%) and small artificial reservoirs (11%). Pools, ponds, small lakes, wetlands and phytothelma were not widely studied. Cladocera (48%) and Copepoda (48%) were the most studied groups. No studies were identified that addressed Notostraca, Anostraca or Conchostraca. The sharp increase in the number of published freshwater studies after 2000 is likely a result of increased internet facilities and the implementation of the Scielo platform. Ecology was most frequently the study focus (~50%), followed by taxonomy. Three journals (two Brazilian and one international) accounted for the publication of 44% of the Brazilian studies on microcrustaceans. We expect the frequency of studies employing newer technologies to increase in the coming years. Based on our findings, we propose that future studies should focus on the least well-studied states and should integrate biogeography and systematic approaches. Further data on the fauna within environmental sub-types in Brazil is required.

Resumo Esse estudo apresenta uma revisão cienciométrica para trabalhos com microcrustáceos de água doce (Copepoda, Ostracoda, Branchiopoda: Cladocera, Anostraca Notostraca e Conchostraca) no Brasil entre 1990-2014. Essa revisão foi baseada em 179 artigos científicos encontrados em quatro bases de dados, usando as seguintes palavras-chave: Microcrustáceos, Copepoda, Cyclopoida, Calanoida, Harpacticoida, Ergasilidae, Chydoridae, Daphniidae, Moinidae, Cladocera, Ostracoda, Conchostraca, Zooplankton, reservatório, rio, lagoas, áreas inundáveis, cavernas, lagos, limnologia, ecologia, aquático, taxonomia, sistemática, morfologia e biogeografia. Não foram encontrados estudos para microcrustáceos de água doce em quatro (Amapá, Roraima, Alagoas e Espírito Santo) dos 27 Estados da Federação Brasileira. Quarenta e cinco por cento dos estudos foram concentrados em três dos estados mais populosos (São Paulo, Minas Gerais e Paraná), os quais têm longa tradição em estudos limnológicos. A maioria dos estudos analisou reservatórios de hidrelétricas (22%), ambientes múltiplos (22%), rios (14%) e pequenos reservatórios artificiais (11%). Ambientes tais como, pequenos lagos, poças, lagoas, brejos e fitotelmatas não foram muito estudados. Cladocera (48%) e Copepoda (48%) foram os grupos mais estudados. Não foram encontrados trabalhos que analisaram Notostraca, Anostraca ou Conchostraca. O salto no número de estudos publicados depois do ano 2000 parece ser resultado do aumento das facilidades da internet e criação da plataforma Scielo. Ecologia foi a área mais focada nos estudos (~50%), seguida pela taxonomia. Três revistas (duas brasileiras e uma internacional) contêm 44% dos artigos publicados sobre microcrustáceos no Brasil. Espera-se que a frequência de estudos utilizando novas tecnologias aumente nos próximos anos. Baseado nos nossos resultados, propõe-se que trabalhos futuros devam focar os estados menos estudados e integrem abordagens biogeográficas e sistemáticas. Mais dados sobre a fauna de microcrustáceos dentro dos tipos de ambiente menos estudados no Brasil também são necessários.

Changes in abundance and composition of a Caribbean coral reef zooplankton community after 25 years / Cambios en abundancia y composición de una comunidad de zooplancton arrecifal en el Caribe 25 años después

Abstract:Coral reef zooplankton represents a key community in coral ecosystems, as they are involved in trophic and biogeochemical dynamics, and recruitment processes. Zooplankton abundance, composition and biomass were surveyed at six stations within the coral reef at Cahuita National Park, Limon, Costa Rica, in order to compare with the only previous study conducted during 1984. Samples were collected monthly (September 2010-August 2011). Seston biomass (0.49-85.87 mg/m3) and total abundance (1 145-112 422 ind./ m3) fluctuated among the months and the stations. Higher values of these two variables were found in the rainiest months (November 2010 and May 2011). A total of 38 taxa were identified, of which calanoid copepods abundance dominated year round (66 %), followed by appendicularians (12 %). Zooplankton mean abundance in this survey resulted 20 times higher (13 184 ± 4 104 ind./m3) than in 1984 (645 ± 84 ind./m3). Copepods and appendicularians were the groups that differed the most, relative to the 1984 study, resulting in 63 and 170 times more abundant overall, respectively. An increase in terrestrial runoff and nutrient input during the past 30 years could explain these differences. High abundances of zooplankton may constitute an important food source for coral reef organisms in Cahuita ecosystem. In addition, zooplankton abundances here reported for Cahuita are among the worldwide highest coral reef zooplankton abundances, and further trophic models can help elucidate its role in coral reef resilience in the Caribbean Coast of Central America.

ResumenEl grupo de zooplancton representa una comunidad clave en los arrecifes de coral. Está involucrado en dinámicas tróficas y biogeoquímicas, y en procesos de reclutamiento. La abundancia, composición y biomasa del zooplancton fueron estudiadas en seis estaciones dentro del arrecife coralino del Parque Nacional Cahuita, para compararlas con el único estudio realizado durante 1984. Las muestras se recolectaron mensualmente (Septiembre 2010-Agosto 2011). La biomasa del seston (0.49-85.87 mg/m3) y la abundancia total (1 145-112 422 ind./m3) fluctuaron entre meses y estaciones. Los valores más altos se encontraron durante los meses más lluviosos (Noviembre 2010 y Mayo 2011). Treinta y ocho taxones fueron identificados, copépodos calanoidos (66 %) y apendicularias (12 %) dominaron la abundancia durante todo el año. La abundancia promedio en este estudio fue 20 veces más alta (13 184 ± 4 104 ind./m3) que en 1984 (645 ± 84 ind./m3). Copépodos y apendicularias fueron los grupos con mayor discrepancia con respecto al estudio de 1984. Un aumento en la descarga de nutrientes de origen terrestre, podría explicar estas grandes diferencias. Abundancias tan altas de zooplancton podrían constituir una importante fuente de alimento para los organismos del arrecife en Cahuita. Las abundancias aquí reportadas colocan al arrecife de Cahuita entre los arrecifes de coral con mayor abundancia de zooplancton en el mundo y estudios futuros en redes tróficas podrían elucidar el papel de esta comunidad en procesos de resiliencia en los arrecifes del Caribe centroamericano.

On Limnocytherina axalapasco, a new freshwater ostracod (Podocopida: Limnocytheridae) from Mexican crater lakes / Limnocytherina axalapasco, un nuevo ostrácodo dulceacuícola (Podocopida: Limnocytheridae) de lagos de cráter mexicanos

Limnocytherina is a genus conformed by 12 species; its distribution in the American continent is known to be exclusively on the North (neartics), but little is reported about its distribution from Mexico (transition zone) and Central America (Neotropics). Different sampling campaigns were undertaken in three crater lakes from the Axalapascos region in east-central Mexico, during 2008, 2009 and 2011. As a product of these campaings, the new species of Limnocytherina axalapasco was found, which displays some intraspecific variability among populations. In this study, we described the taxonomy, the habitat, the ecological preferences and the larval development of this new species. A total of 10 sediment samples (8 littoral, 2 deepest point) were collected from lakes Alchichica, La Preciosa and Quechulac. We found that L. axalapasco is closely related to two North American species: L. posterolimba and L. itasca as well as one Central American species L. royi comb. nov. With the inclusion of L. axalapasco and L. royi to the genus, the distribution of Limnocytherina is extended to Central America. The four most important distinguishing characters of this new species are: 1) valve surface and margins covered with small, spine-like projections; 2) most of the A1 setae with a highly developed setule at distal part, producing a bifurcate appearance; 3) the upper ramus on the hemipenis is elongated, and by far overpasses dorsal/distal margins, distal lobe is triangular and short, while the hook-like process is prominent, outward orientated, and overpassing the tip of the distal lobe; 4) the UR is moderately developed with seta f3 elongated and setae f1 and f2 short. Considering its ecological characteristics and larval development, L. axalapasco was preferably found in alkaline waters dominated by Cl- or HCO3- and Na+ or Mg2+, temperatures ranging between 19.1 to 20.3°C, and dissolved oxygen concentrations from 5 to 6.5mg/L. This species was abundant in deeper (~64m) areas of the saline Alchichica lake, where surface water displayed conductivity values of up to 2 250μS/cm, and the sand with low percentage of silt resulted the preferred substrate. Along with the description of L. axalapasco, we provide additional information on the hemipenis of L. itasca, L. royi and L. sanctipatricii, and we discuss on the Limnocytherina-type of hemipenis.

Limnocytherina es un género conformado por 12 especies; su distribución en el continente Americano se conoce exclusivamente en el norte (zona neártica), pero se sabe poco de su distribución en México (zona de transición) y Centro América (zona neotropical). Luego de diferentes campañas de muestreo en tres lagos cráter de la región de los Axalapascos en la zona centroeste de México, durante 2008, 2009 y 2011, se encontró a Limnocytherina axalapasco, una nueva especie, que mostró variabilidad intraespecífica entre poblaciones. Un total de 10 muestras de sedimentos (8 del litoral, 2 del punto más profundo) fueron recolectadas de los lagos Alchichica, La Preciosa y Quechulac. L. axalapasco esta estrechamente relacionada con dos especies norteamericanas: L. posterolimba y L. itasca, así como con una especie centroamericana Limnocytherina royi comb. nov. Con la inclusión de L. axalapasco y L. royi al género, la distribución de Limnocytherina se extiende hasta Centro América. Los cuatro caracteres distintivos más importantes de esta nueva especie son: 1) superficie y márgenes de valvas cubiertos por pequeñas proyecciones parecidas a espinas; 2) La mayoría de las setas de A1 tienen una setula muy desarrollada en la zona distal, con apariencia de estar bifurcadas; 3) El ramo superior del hemipene es alargado y por mucho sobrepasa los márgenes dorsal/distal; el lóbulo distal es corto y triangular, mientras que el proceso prensil es prominente, orientado externamente y sobrepasa la longitud del lóbulo distal; 4) el UR esta moderadamente desarrollado con la seta f3 alargada y las setas f1 y f2 cortas. Para esta especie se describe también su hábitat, preferencias ecológicas y desarrollo larvario. L. axalapasco prefiere aguas alcalinas dominadas por Cl- o HCO3 - y Na+ o Mg2+, temperaturas entre 19.1 a 20.3°C y concentraciones de oxígeno disuelto de 5 a 6.5 mg/L. Esta especie es más abundante en las zonas profundas (~64m) del lago salino Alchichica, donde la conductividad del agua es de hasta 2 250μS/cm. Arenas con bajos porcentajes de limo parecen ser el sustrato preferido. Aunado a la descripción de L. axalapasco, proveemos información adicional para los hemipenes de L. itasca, L. royi y L. sanctipatricii, y discutimos el tipo de hemipene en Limnocytherina.

Influencia de las macrófitas sobre la estructura poblacional de rotíferos y microscrustáceos en un plano de inundación tropical

The influence of macrophytes on rotifer and microcrustacean assemblage in a tropical floodplain. Most studies on zooplankton ecology have been conducted in open waters. However, it has been considered of great importance to extend such studies to other habitats, such as those generated of macrophytes. We studied the spatial and temporal variation of the microcrustacean and rotifer assemblage structures associated with macrophytes, and compare them with the variation exhibited in open waters. Integrated samples were collected for zooplankton and phytoplankton biomass using a Schindler bottle, in four open water sites and four other sites covered by macrophytes in the floodplain complex of Ayapel (Córdoba, Colombia) during different limnimetric levels. The significant differences in the structure were evaluated using Kruskal & Wallis and discriminant analyses, and the similarity among sampling sites was evaluated using Bray & Curtis analysis. Zooplanktonic richness was favored by macrophytes. However, we did not find a constant spatial pattern for density, and only particular trends apparently conditionated by flood pulses. The presence of Eichhornia azurea (Pontederiaceae) contributed in a significant way with an increase in the diversity and density of benthic taxa. The density of some zooplanktonic groups was related with environmental conditions and phytoplanktonic biomass. Rev. Biol. Trop. 59 (2): 853-870. Epub 2011 June 01.

La mayoría de estudios ecológicos del zooplancton se han realizado en aguas abiertas. No obstante, es importante ampliar la exploración hacia hábitats como el de las macrófitas. En este estudio se evaluó la variación espacio-temporal de la estructura del ensamble de rotíferos y microcrustáceos asociados a macrófitas y se comparó con la variación de su estructura en aguas abiertas, para lo cual se tomaron muestras integradas de zooplancton y biomasa de fitoplancton usando una botella Schindler de 5L en cuatro sitios de aguas abiertas y en cuatro sitios cubiertos por macrófitas durante diferentes niveles limnimétricos en el complejo cenagoso de Ayapel (Córdoba, Colombia). Las diferencias significativas de la estructura se evaluaron mediante Kruskal & Wallis y discriminantes; y la similitud entre sitios de muestreo mediante Bray & Curtis. Las macrófitas favorecieron la riqueza zooplanctónica; sin embargo, no hubo un patrón espacial constante en la densidad, pero sí tendencias particulares condicionadas por el pulso de inundación. La presencia de Eichhornia azurea (Pontederiaceae) contribuyó significativamente a la mayor diversidad y densidad de taxones bentónicos y sólo la densidad de algunos taxones y grupos del zooplancton se relacionó con las condiciones ambientales y la biomasa de fitoplancton.

The invasion of five alien species in the Delta do Parnaíba Environmental Protection Area, Northeastern Brazil

Marine biological invasions have been regarded as one of the major causes of native biodiversity loss, with shipping and aquaculture being the leading contributors for the introductions of alien species in aquatic ecosystems. In the present study, five aquatic alien species (one mollusk, three crustaceans and one fish species) were detected during dives, shore searches and from the fisheries on the coast of the Delta do Parnaíba Environmental Protection Area, in the States of Piauí and Maranhão, Northeastern Brazil. The species were the bicolor purse-oyster Isognomon bicolor, the whiteleg shrimp Litopenaeus vannamei, the giant river prawn Macrobrachium rosenbergii, the Indo-Pacific swimming crab Charybdis hellerii and, the muzzled blenny Omobranchus punctatus. Ballast water (I. bicolor, C. hellerii, and O. punctatus) and aquaculture activities (L. vannamei and M. rosenbergii) in adjacent areas are the most likely vectors of introduction. All exotic species found have potential impact risks to the environment because they are able to compete against native species for resources (food and habitat). Isognomon bicolor share the same habitat and food items with the native bivalve species of mussels and barnacles. Litopenaeus vannamei share the same habitat and food items with the native penaeids such as the pinkspot shrimp Farfantepenaeus brasiliensis, the Southern brown shrimp Farfantepenaeus subtilis, and the Southern white shrimp Litopenaeus schmitti, and in the past few years L. vannamei was responsible for a viral epidemics in the cultivation tanks that could be transmitted to native penaeid shrimps. Charybdis hellerii is also able to cause impacts on the local fisheries as the species can decrease the populations of native portunid crabs which are commercialized in the studied region. Macrobrachium rosenbergii may be sharing natural resources with the Amazon River prawn Macrobrachium amazonicum. Omobranchus punctatus shares habit with the native redlip blenny Ophioblennius atlanticus and other fishes, such as the frillfin goby Bathigobius soporator. Some immediate remedial measures to prevent further introductions from ballast water and shrimp farm ponds should be: (i) to prevent the release of ballast water by ship/vessels in the region; (ii) to reroute all effluent waters from shrimp rearing facilities through an underground or above-ground dry well; (iii) to install adequate sand and gravel filter which will allow passage of water but not livestock; (iv) outdoor shrimp pounds located on floodable land should be diked, and; (v) to promote environmental awareness of those directly involved with ballast water (crews of ship/vessels) and shrimp farms in the region. Rev. Biol. Trop. 58 (3): 909-923. Epub 2010 September 01.

En el Área de Protección Ambiental del Delta Del Río Parnaíba, noreste de Brasil fueron detectadas cinco especies acuáticas invasoras (un molusco, tres crustáceos y un pez): la ostra de dos colores Isognomon bicolor, el camarón patiblanco Litopenaeus vannamei, el camarón gigante de río Macrobrachium rosenbergii, el cangrejo nadador del Indo-Pacifico Charybdis hellerii y el blenio hocicudo Omobranchus punctatus. El agua de lastre (I. bicolor, C. hellerii, y O. punctatus) y la acuicultura (L. vannamei y M. rosenbergii) en áreas adyacentes son los vectores de introducción más probables. Todas las especies exóticas encontradas son potencialmente riesgosas para el ambiente ya que son aptas para competir con las nativas por recursos como alimento y hábitat. Charybdis hellerii también podría causar impacto en el recurso pesquero local, al reducir las poblaciones de cangrejos portúnidos nativos, comercializados en el área de estudio.

Rates of pulmonary infection by pentastomids in lizards species from a restinga habitat in northeastern Brazil / Infecção pulmonar por pentastomídeos em lagartos de restinga do nordeste brasileiro

Pulmonary parasitism by pentastomids was examined in two lizard species inhabiting an area of restinga vegetation (coastal sand dunes) situated in the municipality of Mataraca (6° 29' S and 34° 56' W), on the extreme northern coast of Paraíba State, Brazil. A total of 123 lizards were collected, being 75 specimens of Micrablepharus maximiliani (Gymnophtalmidae) and 48 specimens of Cnemidophorus ocellifer (Teiidae). Only a single species of Pentastomida (Raillietiella mottae) was found parasitizing three females M. maximiliani, with a prevalence of 4 percent and an average infection intensity of 2.3 ± 1.3 (range 1-5). The infection rate by pentastomids encountered in the present study was similar to that seen with other species of restinga lizards. Raillietiella mottae is a generalist parasite species that is probably transmitted by common and widely distributed insects making up part of the diet of many insectivorous lizard species from northeastern Brazil.

O parasitismo por pentastomídeos foi estudado em duas espécies de lagartos de restinga no Nordeste brasileiro Foram realizadas coletas no município de Mataraca (6° 29' S e 34° 56' W), extremo norte do litoral do Estado da Paraíba. Foram coletados 123 lagartos, 75 Micrablepharus maximiliani (Gymnophtalmidae) e 48 Cnemidophorus ocellifer (Teiidae). Apenas uma única espécie de Pentastomida, Raillietiella mottae, foi encontrada parasitando três fêmeas de M. maximiliani, com prevalência de 4 por cento e intensidade média de infecção de 2,3 ± 1,3 (amplitude 1-5). Os dados de prevalência encontrados são relativamente semelhantes aos de outras espécies de lagartos de restinga parasitados por pentastomídeos. Raillietiella mottae é uma espécie de parasita generalista e deve ser transmitida por insetos comuns e de ampla distribuição geográfica presentes na dieta de várias espécies de lagartos insetívoros no Nordeste brasileiro.

Pentastomids infecting an invader lizard, Hemidactylus mabouia (Gekkonidae) in northeastern Brazil / Pentastomídeos infectando um lagarto invasor, Hemidactylus mabouia (Gekkonidae), na região nordeste do Brasil

From January to April 2006, 37 specimens of Hemidactylus mabouia were collected in houses, in the municipality of Barbalha (7° 20' S and 39° 18' W), Ceará State, Northeast Brazil. Among the individuals captured, 17 were infected with pentastomids, totalling a prevalence of 45.9 percent, which did not differ between sexes. Host size did not influence the infection intensity. Two species of pentastomids were found: Raillietiella frenatus and R. mottae. The prevalence of R. frenatus (43.2 percent) was higher than R. mottae (2.7 percent), whereas the infection intensity of R. frenatus was comparatively lower (1.8 ± 1.4) than R. mottae (36 parasites in a single host). Overall mean intensity of infection was 3.8 ± 8.4 pentastomids. We found no pentastomid infecting juvenile geckos. The parameters of infection in this host population are in accordance to the findings of other studies, in which the high parasitism rate was associated to the feeding habits of geckos living in houses and buildings. Hemidactylus mabouia is a new host to R. mottae and the infection by R. frenatus is the first record of the occurrence this pentastomid species in Brazil.

De janeiro a abril de 2006 foram coletados 37 espécimes de Hemidactylus mabouia em domicílios no município de Barbalha (7° 20' S e 39° 18' W), Estado do Ceará, Nordeste do Brasil. Entre os indivíduos capturados, 17 estavam infectados com pentastomídeos, totalizando uma prevalência de 45,9 por cento, sem diferenças significantes entre os sexos. O tamanho dos hospedeiros também não influenciou na intensidade de infecção. Duas espécies de pentastomídeos foram encontradas: Raillietiella frenatus e R. mottae. A prevalência de R. frenatus (43,2 por cento) foi mais alta do que a de R. mottae (2,7 por cento), enquanto que a intensidade média de infecção de R. frenatus foi comparativamente mais baixa (1.8 ± 1.4) do que a de R. mottae (36 parasitas em um único indivíduo). A intensidade geral de infecção foi de 3.8 ± 8.4 pentastomídeos. Não foi encontrado nenhum gecko juvenil infectado por pentastomídeo. Os parâmetros de infecção nesta população de hospedeiros estão de acordo com outros estudos, que indicam altas taxas de parasitismo associadas com os hábitos alimentares de geckos vivendo em domicílios e edificações. Hemidactylus mabouia representa um novo hospedeiro para R. mottae e a infecção por R. frenatus constitui o primeiro registro de ocorrência desta espécie de pentastomídeo no Brasil.

Fecundity of the crustacean Mysidopsis californica (Mysida, Mysidae) under semi-controlled conditions

Mysid crustaceans are frequently used in the laboratory to feed cephalopods and fish, but not along the Pacific coast, where they are scarce. There is no commercial aquaculture of mysids in the Pacific Ocean. To change this situation, we calculate fecundity, survival, and sex ratio of Mysidopsis californica under semi-controlled conditions. Mysids were collected manually using a 500 µm-mesh net along the rocky coast of Mazatlán, Sinaloa, Mexico. They were transferred to three 30 L seawater aquaria in the laboratory, and fed (ad libitum) Artemia nauplii and rotifers. Two generations were obtained. The relationship between the number of juveniles born and parent female lengths showed a rate of 1.56 juveniles released per each unit of increasing parent female length. An average parent female length of 6.92 mm (SD=0.82) gave 9.96 (SD=4.29) released juveniles. The frequency of female length showed a mean of 7.3 mm (SD=0.54), whereas that of juveniles showed a mean of 1.7 mm (SD=0.16). Survival and sex ratios (females-males) varied from 77.7 % to 88.6 % and 2.5:1 to 3.0:1, respectively. Rev. Biol. Trop. 56 (2): 535-539. Epub 2008 June 30.

El objetivo de este trabajo fue calcular la fecundidad, supervivencia y la proporción de sexos de Mysidopsis californica en condiciones semi-controladas. Los animales fueron recolectados manualmente utilizando una red con malla de 500 µm a lo largo de la costa rocosa de Mazatlán, Sinaloa, México. Una vez en el laboratorio fueron colocados en tres acuarios de 30 L cada uno y alimentados con nauplios de Artemia y rotíferos; estudiándose dos generaciones. La relación entre el número de jóvenes nacidos y la longitud de las madres dio una tasa de 1.56 jóvenes nacidos por cada unidad de incremento de la longitud de la hembra. En promedio, hembras de 6.92 mm (SD=0.82) producían 9.96 (SD=4.29) jóvenes. La frecuencia de la longitud promedio de la hembra fue de 7.3 mm (SD=0.54), mientras que los jóvenes medían en promedio 1.7 mm (SD=0.16). La supervivencia y la proporción de sexos (hembrasmachos) varió entre 77.7 % y 88.6 % y entre 2.5:1 y 3.0:1, respectivamente.

Ostracods as indicators of pollution in the lakes of Mysore.

Ostracods are small crustaceans found in aquatic habitats and the present paper deals with the role of water quality index on their population diversity and seasonal fluctuations in the four lakes of Mysore city The present investigation was carried out from July 2004 to June 2005. The study revealed highest water quality index and population density of ostracods during summer and least during winter Dalvoi lake recorded higher waterquality index (125.04), population density (60 l(-1)) but lower species diversity (2 species) of ostracods, whereas Kamana lake recorded lowest water quality index (63.49), population density (40 l(-1)) and highest species diversity (6 species) of ostracods. Increase in the water quality index indicates increase in the pollution load. As water quality index (WQI) increases, population density of ostracods increases but species diversity decreases.

Feeding habits of four species of mesopelagic fishes from the Northern Chilean

The feeding habits of four species of mesopelagic fishes from northern Chile are described: Triphoturus mexicanus, Diogenichtys atlanticus, Vinciguerria lucetia and Cyclothone acclinidens. Samples were captured in September 1988 between 18 degrees 25' and 19 degrees 09'S in the South West Pacific. The quantitative and qualitative analyses of the stomach content showed that the species have a zooplanktophagous opportunistic behavior, mainly predating on Crustaceans, especially on Copepods. The evaluation of the trophic spectrum and diversity of T. mexicanus and C. acclinidens suggests that these are nictoepipelagic species, while D. atlanticus and V. lucetia would be typical mesopelagic.

Se describen los hábitos alimenticios de cuatro especies de peces mesopelágicos del norte de Chile: Triphoturus mexicanus, Diogenichtys atlanticus, Vinciguerria lucetia and Cyclothone acclinidens. Las muestras fueron capturadas en setiembre de 1988 entre 18°25’ y 19°09’ S en el Pacífico suroeste. El análisis cualitativo y cuantitativo del contenido estomacal mostró que las especies tienen un comportamiento zooplantofago oportunista, depredando principalmente crustáceos, especialmente copépodos. La evaluación del espectro trófico y diversidad de T. mexicanus y C. acclinidens sugiere que estas son especies nictoepipelágicas, mientras que D. alanticus y V. lucetia serían mesopelágicas típicas.

An apparatus for the experimental demonstration of behavioural responses of the cyclopoid copepod, Mesocyclops leuckarti sensu lato to light and temperature.

To demonstrate the behavioural responses of Mesocyclops leuckarti sensu lato to light and temperature, an apparatus was designed and fabricated. It was found that light did not effect the orientational response significantly (p > 0.05) compared to the control. However, temperature gradient definitely influenced the orientational response (p < 0.05). The suitability of this apparatus for studying the behavioural response of other aquatic organisms are also discussed.