Using temperature as an independent variable, we were able to explain some 43 and 49% of the variance in the specific absorption coefficient of phytoplankton (a*(λ)) at wavelengths (λ) 443 and 676 nm, respectively, for some 1187 samples collected over a broad range of oceanographic regimes. Through examination of ancillary data, we demonstrate that our results are consistent with the view that the size structure and taxonomic composition of phytoplanktonic communities are regulated by physical processes, for which temperature is often a suitable proxy. Results obtained from multiple-linear regression analysis showed that by using temperature and chlorophyll a concentration, both of which can be retrieved by remote sensing, a larger proportion of the residual variance in a*(λ) could be explained than if chlorophyll a concentration were used alone. Furthermore, as a single independent variable, temperature could explain nearly an equal proportion of the variance of a*(λ) as chlorophyll a. These results show clearly the potential of using satellite-derived temperature data to improve retrieval of phytoplankton biomass from remotely sensed data on ocean colour. KEY WORDS: Phytoplankton community structure · Absorption spectrum · Temperature · Remote sensing Resale or republication not permitted without written consent of the publisher

Water-column primary production was determined by the I4C in situ method during the spring bloom in the North Atlantic Ocean. For the same samples, the parameters of the photosynthesislight (P-I) curve were determined in broad-band light, and in narrow spectral bands for construction of the action spectrum. Using these parameters, with information on the vertical distribution of chlorophyll, measurements of light absorption by particulate materials, and data on surface irradiance, watercolumn production was calculated using 4 different production models. When compared to in situ primary production measurements, the results show that the spectral model, Model 1, is the best estimator of water-column primary production. Model 2 which used broad-band crB (the initial slope of P-I curve, normalized to biomass B) with light integrated over wavelength, and Model 4 (broad-band a* and broad-band light), consistently underestimated production by about 25 % and 60 % respectively. However, Model 3 (in which light is computed using a depth-averaged attenuation coefficient, R and in which a* is assumed to be wavelength-independent) gave water-column primary production estimates not significantly different from in situ values. It is recommended that the spectral model should be applied, whenever possible, in the computations of water-column primary production. If, however, broad-band crB has to be used in the calculations, it is suggested that light at depth be computed if possible using K The use of the fully broad-band model, Model 4, is not recommended. This is because the model gave strongly biased estimates of water-column primary production relative to the observed values.

No abstract

No abstract

Introduction Cultivation of spirulina at commercial-scales relies on analytical grade–based media, which are expensive and so are the product. Purpose This study assessed the biomass, proximate composition, and other useful compounds in Spirulina (Arthrospira fusiformis) produced with a cost-effective culture medium (LCMA), and the results were compared with those from a standard Zarrouk medium–grown spirulina. Methods The LCMA medium was formulated by using a commercial NPK10-20-20 fertilizer as a source of the three major nutrients for spirulina growth, and other three ingredients from Zarrouk medium. The experiment was conducted for 28 days in the glass aquaria under indoor conditions. Standard analytical methods were applied for the determination of proximate composition, chlorophyll, minerals, and vitamins in the spirulina biomass. Result The LCMA medium showed the best growth conditions by accumulating higher chlorophyll content (0.99 ± 0.02%) and dry weight (0.75 ± 0.01 g/100 ml) as well as attaining higher optical density (2.06 at day 15) earlier than the Zarrouk medium. The results of the proximate analysis for spirulina cultured in the LCMA medium were of good quality, with the protein contributing more than 50% of its dry matter. It was further noticed that the LCMA was an ideal medium for optimization of vitamins and some minerals since it recorded a significant amount of most of the analyzed vitamins together with the minerals sodium and potassium compared with the Zarrouk medium. Conclusion It is suggested that LCMA medium could be used as the alternative and cheap medium for maximization of biomass and production of useful biochemical compounds in spirulina species.