We further demonstrate that this approach has the sensitivity to detect changes in algal tissue that result from variation in resource availability (temperature, nutrients), illustrating the potential of NIRS in studies investigating the effects of eutrophication and climate change on coastal algal communities.
Use of NIRS selleck kinase inhibitor to measure algal tissue traits. The nitrogen and carbon NIRS models developed in this study match the accuracy of nitrogen and carbon models developed for other organisms in terrestrial, aquatic, and marine systems. Nitrogen models appear to be consistently accurate across different systems and tissue types. Lawler et al. (2006) developed an effective nitrogen NIRS model to quantify seagrass nutrients (R2 of 0.99), and Hood et al. (2006) developed a useful model to measure the nitrogen content of aquatic seston samples (R2 = 0.87). Calibration NIRS models for nitrogen content in pine needles (R2 = 0.94) (Gillon et al. 1999) and even organic layers in forest soils (R2 = 0.96) (Chodak et al. 2002) have shown a similar accuracy as the calibration model developed in this study.
Our results, in conjunction with these studies, illustrate the effectiveness of NIRS to predict nitrogen content of tissue regardless of the tissue type. Despite the lower coefficient of determination value of our carbon model (R2 = 0.84) relative Selleckchem BGB324 to our nitrogen and phlorotannin models, the carbon model still exhibited high predictive power when tested against the validation set (R2 = 0.95). The lower value could be due to the small range of the carbon values (25%–28% dry weight) in the calibration set. Gillon et al. (1999) found a similarly variable relationship (R2 = 0.86) when measuring the carbon content of senescent pine needles that ranged ∼49%–54%
dry weight. However, when Gillon et al. (1999) increased the range of carbon in the calibration set to ∼32%–54% dry weight by adding green pine needles and leaf litter to the calibration set, the selleck chemical coefficient of determination of the NIRS model increased to R2 = 0.99. Using NIRS to measure variation in plant secondary metabolite concentrations. We aimed to determine if an appropriate NIRS model could be developed to measure phlorotannin content (as phloroglucinol equivalents) in the brown alga S. flavicans as an alternative to traditional wet chemistry methods to aid in algal studies using small tissue samples. The high predictive power (R2 = 0.91) of the phlorotannin model developed in this study demonstrates that NIRS is an accurate alternative method to quantify phlorotannins in Sargassum. Until now, studies investigating secondary metabolites in algae have relied on colorimetric or HPLC methods. Although the precision of NIRS predictions can never be higher than the initial data used to calibrate the models (in this case colorimetric data), the use of NIRS provides valuable advantages over traditional methods.