TY - JOUR A1 - Spijkerman, Elly A1 - Wacker, Alexander A1 - Weithoff, Guntram A1 - Leya, Thomas T1 - Elemental and fatty acid composition of snow algae in Arctic habitats JF - Frontiers in microbiology N2 - Red, orange or green snow is the macroscopic phenomenon comprising different eukaryotic algae. Little is known about the ecology and nutrient regimes in these algal communities. Therefore, eight snow algal communities from five intensively tinted snow fields in western Spitsbergen were analysed for nutrient concentrations and fatty acid (FA) composition. To evaluate the importance of a shift from green to red forms on the FA-variability of the field samples, four snow algal strains were grown under nitrogen replete and moderate light (+N+ML) or N-limited and high light (-N+HL) conditions. All eight field algal communities were dominated by red and orange cysts. Dissolved nutrient concentration of the snow revealed a broad range of NH4+ (<0.005-1.2 mg NI-1) and only low PO43- (< 18 mu g P I-1) levels. The external nutrient concentration did not reflect cellular nutrient ratios as C:N and C:P ratios of the communities were highest at locations containing relatively high concentrations of NH4- and PO43-. Molar N:P ratios ranged from 11 to 21 and did not suggest clear limitation of a single nutrient. On a per carbon basis, we found a 6-fold difference in total FA content between the eight snow algal communities, ranging from 50 to 300 mg FA g C-1. In multivariate analyses total FA content opposed the cellular N:C quota and a large part of the FA variability among field locations originated from the abundant FAs C181n-9, C18 2n-6, and C183n-3. Both field samples and snow algal strains grown under -N+HL conditions had high concentrations of C181n-9. FAs possibly accumulated due to the cessation of growth. Differences in color and nutritional composition between patches of snow algal communities within one snow field were not directly related to nutrient conditions. We propose that the highly patchy distribution of snow algae within and between snow fields may also result from differences in topographical and geological parameters such as slope, melting water rivulets, and rock formation. KW - Arctic snow algal bloom KW - cellular C:N:P ratio KW - ecology KW - extremophiles KW - lipids KW - nutrients KW - psychrophilic. KW - Spitsbergen Y1 - 2012 U6 - https://doi.org/10.3389/fmicb.2012.00380 SN - 1664-302X VL - 3 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Stillman, Richard A. A1 - Railsback, Steven Floyd A1 - Giske, Jarl A1 - Berger, Uta A1 - Grimm, Volker T1 - Making Predictions in a Changing World: The Benefits of Individual-Based Ecology JF - Bioscience N2 - Ecologists urgently need a better ability to predict how environmental change affects biodiversity. We examine individual-based ecology (IBE), a research paradigm that promises better a predictive ability by using individual-based models (IBMs) to represent ecological dynamics as arising from how individuals interact with their environment and with each other. A key advantage of IBMs is that the basis for predictions-fitness maximization by individual organisms-is more general and reliable than the empirical relationships that other models depend on. Case studies illustrate the usefulness and predictive success of long-term IBE programs. The pioneering programs had three phases: conceptualization, implementation, and diversification. Continued validation of models runs throughout these phases. The breakthroughs that make IBE more productive include standards for describing and validating IBMs, improved and standardized theory for individual traits and behavior, software tools, and generalized instead of system-specific IBMs. We provide guidelines for pursuing IBE and a vision for future IBE research. KW - ecology KW - fitness-maximization KW - individual-based KW - modeling KW - prediction Y1 - 2015 U6 - https://doi.org/10.1093/biosci/biu192 SN - 0006-3568 SN - 1525-3244 VL - 65 IS - 2 SP - 140 EP - 150 PB - Oxford Univ. Press CY - Oxford ER -