Temperature Modulates Coccolithophorid Sensitivity of Growth, Photosynthesis and Calcification to Increasing Seawater pCO2

Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2 gradient ranging from ,0.5–250 mmol kg21 (i.e. ,20–6000 matm pCO2) at three different temperatures (i.e. 10, 15, 20uC for E. huxleyi and 15, 20, 25uC for G. oceanica). Both species showed CO2-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO2. CO2 optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO2 concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO2 concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain’s temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean

Giardia duodenalis genotypes and Cryptosporidium species in humans and domestic animals in Côte d'Ivoire: occurrence and evidence for environmental contamination

Giardia duodenalis genotypes and Cryptosporidium species were studied in humans and free-ranging animals living in closed enclaves in Côte d’Ivoire. Three hundred and seven stool samples were tested from humans, and 47 from freely roaming domestic animals (dogs, goats, ducks, chickens). Molecular characterization of the isolates was performed by sequence analysis of a portion of the SSU-rDNA for Giardia and the COWP gene for Cryptosporidium, and a ˇ-giardin SYBR-green real-time PCR was also used to confirm the assignment of Giardia isolates to Assemblages. In humans, genotyping of Giardia assigned many of the sequences (43/56 by the SSU-rDNA gene, and 36/61 by the ˇ-giardin gene) to Assemblage B. The animal species harboured only zoonotic ssemblages A and B, except for dogs, in which host specific Assemblages C and D were also detected. Cryptosporidium meleagridis, C. parvum and C. hominis were detected in humans, while among the animals only chickens were found positive for oocysts, identified as C. meleagridis and C. parvum. The results provide further evidence about the role of freeranging domestic animals living closely with humans in the environmental dissemination and potential transmission of these anthropozoonotic pathogens to humans

Environmental forcing of phytoplankton in a Mediterranean estuary (Guadiana Estuary, southwestern Iberia): a decadal of anthropogenic and climatic influences

Phytoplankton seasonal and interannual variability in theGuadiana upper estuarywas analyzed during 1996–2005, a period that encompassed a climatic controlled reduction in river flow that was superimposed on the construction of a dam. Phytoplankton seasonal patterns revealed an alternation between a persistent light limitation and episodic nutrient limitation. Phytoplankton succession, with early spring diatom blooms and summer–early fall cyanobacterial blooms, was apparently driven by changes in nutrients, water temperature, and turbulence, clearly demonstrating the role of river flow and climate variability. Light intensity in the mixed layer was a prevalent driver of phytoplankton interannual variability, and the increased turbidity caused by the Alqueva dam construction was linked to pronounced decreases in chlorophyll a concentration, particularly at the start and end of the phytoplankton growing period. Decreases in annual maximum and average abundances of diatoms, green algae, and cyanobacteria were also detected. Furthermore, chlorophyll a decreases after dam filling and a decrease in turbidity may point to a shift from light limitation towards a more nutrient-limited mode in the near future