Comment on “Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?” 1Original article by Levi et al. appears in Can. J. Fish. Aquat. Sci. 68(8): 1316–1329 and is available at http://www.nrcresearchpress.com/doi/full/10.1139/f2011-067. Reply by Levi et al. appears in Can. J. Fish. Aquat. Sci. 69: this issue, and is available at http://www.nrcresearchpress.com/doi/full/10.1139/f2012-106.

Levi et al. (2011, Can. J. Fish. Aquat. Sci. 68: 1316–1329) related nutrient concentrations before, during, and after spawning, as well as various measures of channel morphology, to levels of prior timber harvest in seven watersheds on Prince of Wales Island in Southeast Alaska, USA. They assumed that single reaches of seven streams were otherwise similar and that other controls on channel morphology and nutrient dynamics could be ignored relative to the effects of prior timber harvest. In this commentary we show that the seven watersheds were not similar and that the sample set was too small to address geomorphic variability unrelated to timber harvest. Levi et al. failed to consider adequately the natural drivers of spatial and temporal variability in channel morphology and to consider stronger alternate hypotheses for observed channel conditions.

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Spatial and Temporal Variability of Macroinvertebrates in Spawning and Non-Spawning Habitats during a Salmon Run in Southeast Alaska

PLoS ONE ◽

10.1371/journal.pone.0039254 ◽

2012 ◽

Vol 7 (6) ◽

pp. e39254 ◽

Cited By ~ 6

Author(s):

Emily Y. Campbell ◽

Richard W. Merritt ◽

Kenneth W. Cummins ◽

M. Eric Benbow

Keyword(s):

Temporal Variability ◽

Spatial And Temporal Variability ◽

Southeast Alaska ◽

Spawning Habitats

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Spatial and temporal variability in nutrient concentrations in Liverpool Bay, a temperate latitude region of freshwater influence

Ocean Dynamics ◽

10.1007/s10236-011-0463-y ◽

2011 ◽

Vol 61 (12) ◽

pp. 2181-2199 ◽

Cited By ~ 10

Author(s):

Naomi Greenwood ◽

David J. Hydes ◽

Claire Mahaffey ◽

Andrew Wither ◽

Jon Barry ◽

...

Keyword(s):

Temporal Variability ◽

Nutrient Concentrations ◽

Spatial And Temporal Variability ◽

Temperate Latitude ◽

Liverpool Bay ◽

Latitude Region ◽

Freshwater Influence

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CONSIDERING SPATIAL AND TEMPORAL VARIABILITY OF FLOODS IN STREAM RESTORATION: EFFECTS OF HYDROCLIMATE ON THE STABILITY OF CHANNEL MORPHOLOGY AND AQUATIC HABITAT

10.1130/abs/2017am-306938 ◽

2017 ◽

Author(s):

John M. Buffington ◽

Keyword(s):

Temporal Variability ◽

Stream Restoration ◽

Aquatic Habitat ◽

Channel Morphology ◽

Spatial And Temporal Variability ◽

The Stability

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Nutrient Dynamics in a Littoral Sediment Colonized by the Submersed Macrophyte Myriophyllum spicatum

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f85-162 ◽

1985 ◽

Vol 42 (7) ◽

pp. 1303-1311 ◽

Cited By ~ 43

Author(s):

R. Carignan

Keyword(s):

Organic Matter ◽

Nutrient Dynamics ◽

Myriophyllum Spicatum ◽

Turnover Time ◽

Root Activity ◽

Nutrient Concentrations ◽

Spatial And Temporal Variability ◽

Available N ◽

Mineralization Of Organic Matter ◽

Porewater Nutrients

The distributions of porewater reactive phosphorus (RP), NH4+, K, and inorganic carbon (ΣCO2) are compared for sediments colonized by Myriophyllum spicatum (9–40 g∙m−2) and sediments experimentally maintained plant-free. Porewater nutrients are characterized by a high spatial and temporal variability. During the summer months, root activity induces marked reductions in porewater RP and NH4+ between 5 and 38 cm. However, this trend is reversed in spring and fall when higher nutrient concentrations are observed in the colonized sediments, presumably as a result of root decay. Root activity is also associated with higher ΣCO2 and K in the porewaters. Exchangeable NH4+ is the largest pool of available N and exhibits a relatively rapid (9.5–24 d) turnover time in colonized sediments. The mineralization of organic matter is an important source of sediment NH4+ and comparable in quantity with the N requirement of the macrophytes. These results suggest that under conditions of nutrient limitation, the rate of nutrient production from sedimentary organic matter decomposition may be a good predictor of macrophyte growth.

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Spatial and Temporal Variability of Nutrient Dynamics and Ecosystem Metabolism in a Hyper-eutrophic Reservoir Differ Between a Wet and Dry Year

Ecosystems ◽

10.1007/s10021-020-00505-8 ◽

2020 ◽

Cited By ~ 1

Author(s):

Tanner J. Williamson ◽

Michael J. Vanni ◽

William H. Renwick

Keyword(s):

Temporal Variability ◽

Nutrient Dynamics ◽

Ecosystem Metabolism ◽

Spatial And Temporal Variability ◽

Eutrophic Reservoir

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Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2011-067 ◽

2011 ◽

Vol 68 (8) ◽

pp. 1316-1329 ◽

Cited By ~ 18

Author(s):

Peter S. Levi ◽

Jennifer L. Tank ◽

Scott D. Tiegs ◽

Janine Rüegg ◽

Dominic T. Chaloner ◽

...

Keyword(s):

Nutrient Concentration ◽

Pacific Salmon ◽

Timber Harvest ◽

Nutrient Export ◽

Southeast Alaska ◽

Particulate Nitrogen ◽

Nutrient Delivery ◽

Before And After ◽

Nutrient Subsidies ◽

Marine Derived Nutrients

Streams often rely on nutrient subsidies, and variation in nutrient delivery may alter the ecosystem response. Pacific salmon (Oncorhynchus spp.) provide marine-derived nutrients to their natal streams but also cause benthic disturbance, with the net effect determined by watershed and stream characteristics. To understand the factors contributing to variation in salmon-derived nutrients (SDN), we studied nutrient concentration and export in seven streams with varying physical characteristics due to timber harvest (e.g., channel complexity) over three years in Southeast Alaska, USA. Salmon increased concentrations and export of dissolved and particulate nitrogen, phosphorus, and carbon, but the magnitude of increase varied up to 41-fold among streams. The density of live salmon best predicted the increase in nutrient concentration and export, whereas the density of carcasses had a negligible effect. Nutrient export was predicted by transient storage before and after the salmon run. Streams in harvested watersheds with simplified channels had greater nutrient export than those in pristine watersheds with complex channels. However, enrichment from salmon overrode the effect of timber harvest on export during the run. Our study demonstrates that enrichment via SDN is short-lived and related to run size, whereas timber harvest and carcasses exert little influence on SDN dynamics.

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Reply to comment by Jackson and Martin on “Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?” 1Original article by Levi et al. appears in Can. J. Fish. Aquat. Sci. 68(8): 1316–1329 and is available at http://www.nrcresearchpress.com/doi/full/10.1139/f2011-067. Comment by Jackson and Martin appears in Can. J. Fish. Aquat. Sci. 69: this issue, and is available at http://www.nrcresearchpress.com/doi/full/10.1139/f2012-104.

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2012-106 ◽

2012 ◽

Vol 69 (11) ◽

pp. 1898-1901

Author(s):

Peter S. Levi ◽

Jennifer L. Tank ◽

Scott D. Tiegs ◽

Janine Rüegg ◽

Dominic T. Chaloner ◽

...

Keyword(s):

Natural Variation ◽

Nutrient Dynamics ◽

Sampling Design ◽

Timber Harvest ◽

Usda Forest Service ◽

Southeast Alaska ◽

Watershed Characteristics ◽

Stream Geomorphology ◽

Alternative Hypotheses

The stated goal of Levi et al. (2011, Can. J. Fish. Aquat. Sci. 68: 1316–1329) was to determine the influence of geomorphic complexity on the dynamics of salmon-derived nutrients. We studied seven streams in Southeast Alaska with varying degrees of historical (mid-1900s) timber harvest and, as a result, differences in stream geomorphology. In a comment on our study, Jackson and Martin (2012, Can. J. Fish. Aquat. Sci. 69: this issue) suggest that the geomorphic complexity we ascribe to timber harvest may be due to natural variation in watershed characteristics and offer alternative hypotheses. We sought to reduce the natural variation among our study streams by using a stratified sampling design (i.e., selecting reaches classified as floodplain 4 or 5 by the USDA Forest Service), but acknowledge that, as with any ecological field study, alternative hypotheses may exist to explain observed patterns in ecological responses. We maintain that our study design was sufficiently robust (i.e., 300 m reaches studied in seven streams for 3 years, totaling 21 stream-years) to draw inferences about the influence of salmon on streamwater nutrients and, secondarily, the role of geomorphic variation in mediating nutrient dynamics. Our data also support our finding that the legacy of timber harvest altered nutrient dynamics in salmon-bearing streams via alterations to stream geomorphology that were quantifiable.

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