Effects of water and substratum nutrient supplies on lotic periphyton growth: An integrated bioassay.
Abstract: Effects
of substratum and
water nutrient purterbations on periphyton growth were assessed in a
nutrient-poor
stream by combining a substratum enrichment technique with a
flow-through
bioassay system. Periphyton growth (chlorophyll a, total
biovolume)
responded to combined influences of water and substratum enrichment in
an additive manner when both compartments were amended with N and P to
yield an optimal ratio (N:P ~16:1). When NO3-N was added to
the
substratum and PO4-P to the water, algal growth response was
synergistic.
Analysis of the vertical distributions of P fractions in cores taken
from
nutrient-diffusing substrata indicates that attached microorganisms
mediate
P release from underlying substrata, acting as a filter or temporary
sink.
Nutrient-diffusing substrata are useful detectors of limiting nutrients
in aquatic systems; however, their function and application differ from
water enrichment assays where nutrients are added at a constant
rate.
Differences are partially attributed to spatial and temporal
variability
of nutrient release and the strictly localized influence of substratum
flora on ambient water chemistry.
Pringle, C.M. 1987. Effects of water and substratum nutrient supplies on lotic periphyton growth: An integrated bioassay. Canadian Journal of Fisheries and Aquatic Sciences 44: 619-629.
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