Document Type

Article

Journal/Book Title/Conference

Canadian Journal of Fisheries and Aquatic Sciences

Volume

54

Issue

5

Publisher

National Research Council Canada

Publication Date

1997

First Page

1177

Last Page

1189

DOI

10.1139/cjfas-54-5-1177

Abstract

We investigated how epilimnetic fertilization would affect chlorophyll levels and light penetration of oligotrophic sockeye salmon (Oncorhynchus nerka) lakes and how the resulting self-shading would affect primary production of the prominent deep chlorophyll maxima (DCM) of the lakes. Epilimnetic nutrient additions to large mesocosms (330 m3) in Redfish Lake, Idaho, increased levels of primary productivity and chlorophyll a but decreased Secchi depths and light available in the metalimnion and hypolimnion. Redfish Lake and other Sawtooth Valley (Idaho) lakes had DCM in which the mean chlorophyll a peaks were 240-1000% of mean epilimnetic chlorophyll a concentrations. The DCM existed at low light levels and accounted for 36-72% of the lakes' primary production. Simulations using photosynthesis-irradiance (P-I) curves demonstrated that fertilization would increase predicted water column primary production by 75-101%. Most of this increase occurred in the epilimnion, with only a slight decrease occurring in the DCM as the result of increased shading.

Comments

Originally published by the National Research Council - Canada. Publisher's PDF can be accessed through the Canadian Journal of Fisheries and Aquatic Sciences.

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