Immediately after incubations in May 2011, macroalgae were scraped from plates, rinsed in freshwater, sorted by species and dried at 60°C for 48 h to estimate biomass (g dry weight, DW). In the case of the encrusting species, we selected 2 × 2 cm rock pieces colonized with encrusting coralline species. These were oven-dried for 48 h at 50°C and weighed for dry-weights. We then placed rock pieces in hydrochloric acid (0.5 M HCl) for 48 h to remove the calcium selleck screening library carbonate. Rock pieces were then rinsed with freshwater, oven-dried for 24 h and then re-weighed. The difference in the dry-weights, i.e., before and after the HCl treatment, was used to obtain the biomass of the algae per 4 cm2 and the average

of 40 squares allowed us to estimate the biomass in our plates at the end of the experimental period. Respiration and productivity were estimated through oxygen fluxes by regressing oxygen

amount produced or consumed (μmol) through time (s−1) during dark and light periods of increasing intensities. Estimations were normalized by assemblage surface (64 cm2) or biomass (May 2011) and volume of incubation chamber (12, 15 or 47 L, measured with plates inside the chamber). Additionally, estimates of respiration and productivity were also normalized by control blanks (incubations performed simultaneously https://www.selleckchem.com/products/Metformin-hydrochloride(Glucophage).html with only filtered seawater) to control for rates of respiration and production of bacteria and phytoplankton. The variables Respiration, Photosynthetic efficiency at

Florfenicol low light irradiance (alpha, α) and Light compensation point were measured as surrogates of ecosystem functioning. Respiration of assemblages (μmol O2 · s−1) corresponded to the oxygen consumption rate during the dark period and we assessed net primary productivity (μmol O2 · s−1) as the productivity recorded at different irradiance intensities in order to calculate alpha. Both variables were calculated by plotting oxygen concentration over incubation time and fitting a linear regression line to calculate rates of oxygen change. Alpha (μmol O2 · μmol photons · m−2), was estimated as the slope of P-I relationship at light-limited irradiances (up to 87 μmol photons · m−2 · s−1), through linear regressions. Regressions were also used to estimate light compensation point of assemblages, the irradiance level at which respiration rate is equal to photosynthetic rate and net oxygen exchange is zero. General linear models were performed to investigate the influence of S. muticum (presence or absence) on each of the biological responses examined: respiration, alpha and light compensation point. After checking for normality using Normal Quantile plots, all response variables were log-transformed and linearity and normality of residual distributions were obtained. Homoscedasticity was assessed by graphical examination of the residuals. We used two biodiversity components (i.e.