Reproduction and respiration of a climate change indicator species: effect of temperature and variable food in the copepod Centropages chierchiae

The abundance of the calanoid copepod Centropages chierchiae has increased at the northern limits of its distribution in recent decades, mainly due to oceanic climate forcing, suggesting this as a key species in monitoring climate change. Laboratory experiments were conducted to study the combined effect of temperature, food type and concentration on the egg production rate (EPR) and hatching success (HS) of C. chierchiae. Females were fed on two monoalgal diets (Gymnodinium sp. and Phaeodactylum tricornutum) at two food concentrations and at three different temperatures (13, 19, 24C). Respiration rates of both genders were measured at four different temperatures (8, 13, 19, 24C). EPR was significantly different between temperatures and food concentrations, the maximum EPR being attained when the copepods were exposed to high food levels and at 19C. Prey type significantly influenced EPR; feeding on P. tricornutum resulted in higher egg production than Gymnodinium sp. HS was significantly lower at 13C than at 19 and 24C and higher with Gymnodinium sp. Respiration rates were sex independent and increased exponentially with temperature. To maintain basal metabolism, the minimum food intake of P. tricornutum ranged between 0.4 and 1.8 g C and for Gymnodinium sp. between 0.03 and 0.13 g C. Food intake was always higher than the metabolic demands, except for the highest temperature tested (24C). The present results confirm the sensitivity of C. chierchiae to temperature variations and may help in understanding the successful expansion of its distribution towards northern latitudes.Portuguese Science and Technology Foundation (FCT) [PTDC/MAR/098643/2008, PTDC/MAR/111304/2009, PTDC/MAR/0908066/2008]; FCT [SFRH/BD/28198/2006]; [SFRH/BPD/38332/2007

Hydrocarbon Contamination Decreases Mating Success in a Marine Planktonic Copepod

The mating behavior and the mating success of copepods rely on chemoreception to locate and track a sexual partner. However, the potential impact of the water-soluble fraction of hydrocarbons on these aspects of copepod reproduction has never been tested despite the widely acknowledged acute chemosensory abilities of copepods. I examined whether three concentrations of the water-soluble fraction of diesel oil (0.01%, 0.1% and 1%) impacts (i) the swimming behavior of both adult males and females of the widespread calanoid copepod Temora longcornis, and (ii) the ability of males to locate, track and mate with females. The three concentrations of the water-soluble fraction of diesel oil (WSF) significantly and non-significantly affect female and male swimming velocities, respectively. In contrast, both the complexity of male and female swimming paths significantly decreased with increasing WSF concentrations, hence suggesting a sex-specific sensitivity to WSF contaminated seawater. In addition, the three WSF concentrations impacted both T. longicornis mating behavior and mating success. Specifically, the ability of males to detect female pheromone trails, to accurately follow trails and to successfully track a female significantly decreased with increasing WSF concentrations. This led to a significant decrease in contact and capture rates from control to WSF contaminated seawater. These results indicate that hydrocarbon contamination of seawater decreases the ability of male copepods to detect and track a female, hence suggest an overall impact on population fitness and dynamics

Molecular Systematic of Three Species of Oithona (Copepoda, Cyclopoida) from the Atlantic Ocean: Comparative Analysis Using 28S rDNA

Species of Oithona (Copepoda, Cyclopoida) are highly abundant, ecologically important, and widely distributed throughout the world oceans. Although there are valid and detailed descriptions of the species, routine species identifications remain challenging due to their small size, subtle morphological diagnostic traits, and the description of geographic forms or varieties. This study examined three species of Oithona (O. similis, O. atlantica and O. nana) occurring in the Argentine sector of the South Atlantic Ocean based on DNA sequence variation of a 575 base-pair region of 28S rDNA, with comparative analysis of these species from other North and South Atlantic regions. DNA sequence variation clearly resolved and discriminated the species, and revealed low levels of intraspecific variation among North and South Atlantic populations of each species. The 28S rDNA region was thus shown to provide an accurate and reliable means of identifying the species throughout the sampled domain. Analysis of 28S rDNA variation for additional species collected throughout the global ocean will be useful to accurately characterize biogeographical distributions of the species and to examine phylogenetic relationships among them

Population ecology of the planktonic shrimp Lucifer faxoni Borradaile, 1915 (Crustacea, Sergestoidea, Luciferidae) of the southeastern coast of Brazil

Luciferid shrimps have short life spans and a rapid turnover of generations, engage in sequential spawning, and protect their eggs during incubation. This study investigates the ecology of Lucifer faxoni Borradaile, 1915 in the littoral zone, Ubatuba region, São Paulo. Sampling was conducted monthly from July 2005 to December 2006 using a Renfro net trawled over a distance of 50 m for a total sampling effort of 50 m² at each station. Nine stations were sampled, ranging from 1 to 15 m deep. Three stations each were grouped into zones 1, 2 and 3 (Z1, Z2 and Z3). Monthly values of salinity, temperature and rainfall were recorded at each station. The pre-buccal somite length (SL) of each specimen was measured. The results showed that in shallower zones (Z1 and Z2), 6306 individuals were captured, whereas in the deeper zone (Z3), 3808 specimens were captured, but no significant differences in SL was detected between the specimens from Z1 and Z2 and those from Z3 (ANOVA, p=0.25). The abundance of shrimps did not differ significantly between seasons (Tukey's test, p=0.02) except in the spring. The sex ratio differed significantly over the seasons (&#967;², pEste estudo analisa a ecologia de Lucifer faxoni Borradaile, 1915 em Ubatuba, São Paulo. Os indivíduos foram coletados mensalmente de julho de 2005 a dezembro de 2006, com uma rede de Renfro, arrastada por uma distância de 50 m, totalizando um esforço amostral de 50 m² em cada ponto de coleta. Nove pontos foram amostrados, variando de 1 a 15 m de profundidade. Cada 3 pontos foram agrupados em 3 zonas (Z1, Z2 e Z3). Os valores de salinidade, temperatura e pluviosidade foram registrados mensalmente em cada transecto. Os espécimes foram medidos quanto ao comprimento do somito pré-bucal (SL). Os resultados mostram que nas zonas mais rasas (Z1 e Z2) foram coletados 6306 indivíduos, enquanto que na mais profunda (Z3) obteve-se 3808 espécimes, não havendo diferença estatística entre as zonas (ANOVA, p=0.25). A abundância não diferiu estatisticamente entre as estações do ano (Tukey, p=0.02), exceto para a primavera. Em todas as estações amostradas, o sex ratio diferiu estatisticamente (&#967;², p< 0.05). Os fatores ambientais aqui analisados apresentaram relação estreita com a distribuição espaço-temporal de L. faxoni. A pluviosidade influenciou diretamente a salinidade, que provocou o deslocamento dos camarões L. faxoni para áreas mais profundas

BIOLOGIE COMPARÉEENTRE ESPÈCES VICARIANTES ET COMMUNESDE COPÉPODESDANS UN ÉCOSYSTÈME NÉRITIQUEEN MÉDITERRANÉE ET EN MANCHE

International audienc

BIOLOGIE COMPARÉEENTRE ESPÈCES VICARIANTES ET COMMUNESDE COPÉPODESDANS UN ÉCOSYSTÈME NÉRITIQUEEN MÉDITERRANÉE ET EN MANCHE

International audienc