Trends in planktonic copepod diversity in reservoirs and lotic stretches in a large river basin in South America

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ecological aspects and sexual maturity of a southwestern Atlantic population of the planktonic shrimp Lucifer faxoni (Decapoda: Sergestoidea)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antimicrobial activity of root canal irrigants associated with cetrimide against biofilm and planktonic Enterococcus Faecalis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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 (χ², p<0.05). The results were closely associated with environmental factors with respect to the spatial and seasonal distribution of L. faxoni. Rainfall affected salinity directly, and contributed to the displacement of these shrimps to deeper areas.

Structural and Functional Insights from the Metagenome of an Acidic Hot Spring Microbial Planktonic Community in the Colombian Andes

A taxonomic and annotated functional description of microbial life was deduced from 53 Mb of metagenomic sequence retrieved from a planktonic fraction of the Neotropical high Andean (3,973 meters above sea level) acidic hot spring El Coquito (EC). A classification of unassembled metagenomic reads using different databases showed a high proportion of Gammaproteobacteria and Alphaproteobacteria (in total read affiliation), and through taxonomic affiliation of 16S rRNA gene fragments we observed the presence of Proteobacteria, micro-algae chloroplast and Firmicutes. Reads mapped against the genomes Acidiphilium cryptum JF-5, Legionella pneumophila str. Corby and Acidithiobacillus caldus revealed the presence of transposase-like sequences, potentially involved in horizontal gene transfer. Functional annotation and hierarchical comparison with different datasets obtained by pyrosequencing in different ecosystems showed that the microbial community also contained extensive DNA repair systems, possibly to cope with ultraviolet radiation at such high altitudes. Analysis of genes involved in the nitrogen cycle indicated the presence of dissimilatory nitrate reduction to N2 (narGHI, nirS, norBCDQ and nosZ), associated with Proteobacteria-like sequences. Genes involved in the sulfur cycle (cysDN, cysNC and aprA) indicated adenylsulfate and sulfite production that were affiliated to several bacterial species. In summary, metagenomic sequence data provided insight regarding the structure and possible functions of this hot spring microbial community, describing some groups potentially involved in the nitrogen and sulfur cycling in this environment. Citation: Jimenez DJ, Andreote FD, Chaves D, Montana JS, Osorio-Forero C, et al. (2012) Structural and Functional Insights from the Metagenome of an Acidic Hot Spring Microbial Planktonic Community in the Colombian Andes. PLoS ONE 7(12): e52069. doi:10.1371/journal.pone.0052069

Planktonic community structure and variability in the Canary Islands waters: the role of microplankton

[ES] En este trabajo hemos contribuido al estudio de la estructura de la comunidad planctónica y a su variabilidad temporal, utilizando un enfoque de end-to-end , desde las bacterias hasta el mesozooplancton haciendo especial énfasis en el microplancton. Nuestro trabajo muestra la importancia de los efectos bottom-up y top-down que regulan la estructura de las comunidades planctónicas.

The structure of planktonic communities under variable coastal upwelling conditions off Cape Ghir (31ºN), in the Canary Current System (NW Africa)

Universidad de Las Palmas de Gran Canaria. Facultad de Ciencias del Mar. Programa de doctorado en Oceanografía. Diploma de Estudios Avanzados

Short-term variability and trophic interactions within planktonic community in subtropical waters of he Canary Islands (Northeast atlantic)

ES]Los giros subtropicales abarcan grandes áreas del océano donde la productividad del ecosistema se sostiene a través del reciclado de materia y energía. En estas aguas, la interacción entre la disponibilidad de recursos y la presión de los niveles tróficos superiores determina la dinámica de la comunidad planctónica. Sin embargo, en aguas subtropicales, el conocimiento de la variabilidad temporal o el papel de los diferentes componentes de la comunidad dentro de la red trófica es bastante limitado. En esta tesis se evalúa la variabilidad a corto plazo de los diferentes componentes de la comunidad planctónica. El picoplancton dominó la comunidad salvo durante la época productiva, en la que los organismos autótrofos de mayor tamaño desempeñaron un papel destacado. Nuestros resultados muestran como la variabilidad estacional está relacionada con fuerzas “bottom-up”, mientras que los procesos “top-down” dominan a una escala de tiempo más corta. Encontramos que el microzooplancton ejerce un gran impacto sobre la comunidad microbiana, en organismos tanto autótrofos como heterótrofos. Además, observamos un acoplamiento muy estrecho entre estos consumidores y sus presas. Otro mecanismo que regula la estructura planctónica es la depredación de los migradores verticales sobre el zooplancton. Así, la variabilidad del mesozooplancton epipelágico está controlada por un ciclo de depredación vinculado a la iluminación de la luna. En este trabajo realizamos una simulación de esta variabilidad con la que se obtuvieron valores de mortalidad comunitaria de los que derivamos el flujo de carbono activo hacia la zona mesopelágica. Estos valores calculados de transporte activo de carbono son del mismo orden de magnitud que el flujo gravitacional en aguas subtropicales. En el Atlántico noreste la comunidad marina también podría estar influenciada por las tormentas de polvo sahariano que ocurren con gran frecuencia en la zona. En este sentido, se estudió la respuesta de la comunidad planctónica en un período de deposición de polvo atmosférico de gran intensidad, en el año 2010, sin observar una clara respuesta en términos de producción primaria. Por el contrario, la biomasa de diatomeas y mesozooplancton sí se vio aumentada en gran medida tras el paso de una fuerte tormenta de polvo del Sáhara, mientras que los organismos autótrofos de menor tamaño se vieron afectados negativamente. Los resultados de esta tesis suponen una contribución importante para entender la dinámica planctónica tan compleja en los ecosistemas subtropicales, y además, pone de manifiesto la necesidad de llevar a cabo muestreos oceanográficos a escalas de tiempo más cortas.

Planktonic potential CO2 emission calculation: preliminary results by applying an adapted enzymatic methodology to marine ecosystems

[EN]Isocitrate Dehydrogenase (IDH) is a key enzyme in the Krebs cycle, being responsible for the production of one of the three CO2 molecules related to cellular respiration. In order to measure the potential CO2 production linked to the marine planktonic community we have adapted an enzymatic methodology. Preliminary results show that different proportions of autotrophs, heterotrophs and mixotrophs and their metabolic pathways, lead to different relationships between potential CO2 emission and potential O2 consumption during cellular respiration. Although more experiments need to be made, this methodology is leading to a better understanding of cellular respiration in marine samples and their impact on the food chain, vertical Carbon flux and the current sequestering capacity for anthropogenic CO2.

Palaeoceanographic changes in the North Atlantic during the Mid-Pleistocene Transition (MIS 31-19) as inferred from planktonic foraminiferal and calcium carbonate records

Marine sediments from the Integrated Ocean Drilling Project (IODP) Site U1314 (56.36°N, 27.88°W), in the subpolar North Atlantic, were studied for their planktonic foraminifera, calcium carbonate content, and Neogloboqudrina pachyderma sinistral (sin.) δ13C records in order to reconstruct surface and intermediate conditions in this region during the Mid-Pleistocene Transition (MPT). Variations in the palaeoceanography and regional dynamics of the Arctic Front were estimated by comparing CaCO3 content, planktonic foraminiferal species abundances, carbon isotopes and ice-rafted debris (IRD) data from Site U1314 with published data from other North Atlantic sites. Site U1314 exhibited high abundances of the polar planktonic foraminifera N. pachyderma sin. and low CaCO3 content until Marine Isotope Stage (MIS) 26, indicating a relatively southeastward position of the Arctic Front (AF) and penetration of colder and low-salinity surface arctic water-masses. Changing conditions after MIS 25, with oscillations in the position of the AF, caused an increase in the northward export of the warmer North Atlantic Current (NAC), indicated by greater abundances of non-polar planktonic foraminifera and higher CaCO3. The N. pachyderma sin. δ13C data indicate good ventilation of the upper part of the intermediate water layer in the eastern North Atlantic during both glacial and interglacial stages, except during Terminations 24/23, 22/21 and 20/1. In addition, for N. pachyderma (sin.) we distinguished two morphotypes: non-encrusted and heavily encrusted test. Results indicate that increases in the encrusted morphotype and lower planktonic foraminiferal diversity are related to the intensification of glacial conditions (lower sea-surface temperatures, sea-ice formation) during MIS 22 and 20.

Different Early Post-Settlement Strategies Between American Lobsters Homarus Americanus and Rock Crabs Cancer Irroratus in the Gulf of Maine

The abundance of many invertebrates with planktonic larval stages can be determined shortly after they reach the benthos. In this study, we quantified patterns of abundance and habitat utilization of early benthic phases of the American lobster Homarus americanus and the rock crab Cancer irroratus. These 2 decapods are among the most common and abundant macroinvertebrates in coastal zones of the Gulf of Maine, with similar densities of larger individuals. Settlement and early postsettlement survival indicate that lobsters are highly substrate-specific early in life, settling predominantly in cobble beds. Crabs appear to be less selective, setting both in cobble and sand. Cumulative settlement of crabs, inferred from weekly censuses over the summer, was an order of magnitude greater than that of lobsters over the same time period. However, only crabs showed significant postsettlement losses. Although the identity of specific predators is unknown, predator exclusion experiments and placement of vacant uninhabited nursery habitat suggested that post-settlement mortality rather than emigration was responsible for these losses. The selective habitat-seeking behavior and lower post-settlement mortality of lobsters is consistent with their lower fecundity and later onset of reproductive maturity. The patterns observed for crabs, however, suggest a different strategy which is more in accordance with their higher fecundity and earlier onset of maturity. It is possible that lower fecundity but greater per-egg investment, along with strict habitat selection at settlement and lower post-settlement mortality, allows adult lobster populations to equal adult populations of crabs. This occurs despite crabs being more fecund and less habitat-selective settlers but sustaining higher postsettlement mortality.

Assessment of Skill and Portability in Regional Marine Biogeochemical Models: Role of Multiple Planktonic Groups

Application of biogeochemical models to the study of marine ecosystems is pervasive, yet objective quantification of these models' performance is rare. Here, 12 lower trophic level models of varying complexity are objectively assessed in two distinct regions (equatorial Pacific and Arabian Sea). Each model was run within an identical one-dimensional physical framework. A consistent variational adjoint implementation assimilating chlorophyll-a, nitrate, export, and primary productivity was applied and the same metrics were used to assess model skill. Experiments were performed in which data were assimilated from each site individually and from both sites simultaneously. A cross-validation experiment was also conducted whereby data were assimilated from one site and the resulting optimal parameters were used to generate a simulation for the second site. When a single pelagic regime is considered, the simplest models fit the data as well as those with multiple phytoplankton functional groups. However, those with multiple phytoplankton functional groups produced lower misfits when the models are required to simulate both regimes using identical parameter values. The cross-validation experiments revealed that as long as only a few key biogeochemical parameters were optimized, the models with greater phytoplankton complexity were generally more portable. Furthermore, models with multiple zooplankton compartments did not necessarily outperform models with single zooplankton compartments, even when zooplankton biomass data are assimilated. Finally, even when different models produced similar least squares model-data misfits, they often did so via very different element flow pathways, highlighting the need for more comprehensive data sets that uniquely constrain these pathways.