Within a taxon, multichannel feeding was a result of specialization among individuals in energy channel usage, with 37 of 56 individual consumers estimated to derive >80% of their EAA from a single channel. In contrast, mobile (fish) taxa at higher trophic levels used more equal proportions of each channel, ranging from 19% to 47% pelagically derived energy. Invertebrates tended to focus on either pelagic or benthic energy, deriving 13–67% of their EAA from pelagic sources. We found evidence for multichannel feeding within the community at the species level. With this EAA isotopic library, we then generated probability distributions for the most important sources of production for each individual consumer and species using a bootstrap-resampling LDA approach. With this model, we were able to correctly classify nearly 90% of producer samples to their original groupings, a significant improvement on traditional bulk isotopic analysis. Using EAA δ 13C data, we employed linear discriminant analysis (LDA) to assess how distinct EAA δ 13C values were between local pelagic (phytoplankton/particulate organic matter), and benthic (kelps, red algae, and green algae) endmembers. We measured bulk tissue δ 13C and δ 15N for >120 samples of these we analyzed δ 13C values of six essential amino acids (EAA) from nine primary producer groups ( n = 41) and 11 representative nearshore consumer taxa ( n = 56). Here, we use bulk tissue isotopic analysis along with carbon isotope (δ 13C) analysis of individual amino acids to characterize the relative contribution of pelagic and benthic energy sources to a kelp forest consumer community in northern Chile. However, the mechanisms underlying this “multichannel” feeding remain poorly understood, especially for aquatic ecosystems that pose unique logistical constraints given the diversity of potential energy channels. The widespread importance of variable types of primary production, or energy channels, to consumer communities has become increasingly apparent.
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