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Water color affects lake stable carbon isotope but not the food source for yellow perch.
Greenfield, Ben1,2, Wilson, Karen1, 1 2
ABSTRACT- Water color may affect energy use at the base of the food web by providing organic substrate for bacterial respiration. Water color may also affect energy transfer between organisms by reducing light penetration and consequently changing predation patterns. To examine the effect of color on lake metabolism and fish food source, we examined the stable carbon isotopes of 5 taxa across 12 lakes ranging widely in water color. The taxa were selected to represent all lake habitats: littoral (snails and crayfish), pelagic (mussels and juvenile yellow perch), and profundal (chironomids). Across all taxa, analysis of covariance indicated a significant quadratic relationship between water color and 13C (R2=0.76; p<0.001). For littoral and pelagic organisms, single taxa models had statistically similar slopes and explained significant variability (R2 between 0.46 and 0.75). For profundal chironomids, the model did not explain significant variability (R2=0.26; p>0.25), suggesting that profundal carbon metabolism is not strongly related to water column color. We used a simple two part mixing model to evaluate percent littoral versus pelagic carbon consumed by adult yellow perch for 10 lakes. Model results indicated that perch consumed between 30 and 100% littoral carbon but that the proportion was not related to water color (p>0.9). Our results indicate that color has a significant impact on carbon metabolism in the lake littoral and pelagic zones but not on fish foraging patterns.
KEY WORDS: stable isotope, perca flavescens, water color, lake metabolism