Spatial variability of stable isotopes and fossil pigments in surface sediments of Alaskan coastal lakes: Constraints on quantitative estimates of past salmon abundance

Brock, Curtis S.; Leavitt, Peter R.; Schindler, Daniel E.; Johnson, Susan P.; Moore, Jonathan W.

doi:10.4319/lo.2006.51.4.1637

Cited by 26 publications

(27 citation statements)

References 43 publications

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“…4). Analogous to limnological studies (Brock et al 2006), sedimentary concentrations of labile pigments (e.g. peridinin) were negatively related to depth (R 2 00.13, P 00.18).…”

Section: Interpretation Of Fjord Sedimentary Recordsmentioning

confidence: 90%

Spatial distribution of diatom and pigment sedimentary records in surface sediments in Doubtful Sound, Fiordland, New Zealand

Schüller

Savage

2011

New Zealand Journal of Marine and Freshwater Research

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Algal remains (pigment concentrations, diatom frustules) and organic matter sources (d 15 N, d13 C) in surface sediments (0Á2 cm) were quantified and related to environmental gradients in Doubtful Sound, Fiordland, New Zealand. Sedimentary pigment concentrations, in particular diatoxanthin and fucoxanthin (diatom biomarkers) were elevated near Malaspina Reach, which experiences greater incident irradiance and mixing of silica-rich freshwater with nutrient-rich marine water. In contrast, diatom frustules were recovered in low concentrations in deep basins including Malaspina Reach, most likely related to dissolution and grazing. Spatial variability in pigments in Doubtful Sound was mainly correlated with light conditions (incident irradiance, chromophoric dissolved organic matter). By contrast, diatoms were principally correlated with salinity gradients (effective freshwater depth) and water column stratification (mixing). This study highlights the importance of using complementary sedimentary proxies when reconstructing algal abundance and community composition in fjord environments.

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“…4). Analogous to limnological studies (Brock et al 2006), sedimentary concentrations of labile pigments (e.g. peridinin) were negatively related to depth (R 2 00.13, P 00.18).…”

Section: Interpretation Of Fjord Sedimentary Recordsmentioning

confidence: 90%

Spatial distribution of diatom and pigment sedimentary records in surface sediments in Doubtful Sound, Fiordland, New Zealand

Schüller

Savage

2011

New Zealand Journal of Marine and Freshwater Research

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“…5) to centuries (Figs. 3, 4), responses of algae to N and P supplements from salmon are much less predictable on annual timescales (e.g., Mitchell and Lamberti 2005;Brock et al 2006). In streams, disturbance of the benthic environment by spawning salmon may restrict algal growth (Mitchell and Lamberti 2005) and can facilitate MDN export to coastal lakes and estuaries (Chaloner et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…However, because past and present algal communities in these and other regional lakes are composed mainly of diatoms Brock et al 2006), and because the diatom indicator diatoxanthin was the predominant pigment (mean 40-90%) in all fossil carotenoid assemblages (P. R. Leavitt unpubl. data), only time series of diatoxanthin were used for subsequent statistical analyses.…”

Section: Methodsmentioning

confidence: 99%

“…For example, salmon are enriched in 15 N relative to 14 N because they feed at a relatively high trophic position in marine environments, where they accumulate most of their biomass (Welch and Parsons 1993). Therefore, when semelparous anadromous salmon spawn, they release N of an elevated d 15 N signature that can label both the freshwater web and lake sediments in proportion to spawner density (Finney et al 2000;Brock et al 2006). Further, such sedimentary N isotope ratios can be used to reconstruct past densities of spawning salmon when the relationship between salmon density and sedimentary d 15 N can be established .…”

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confidence: 99%

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Variable effects of marine‐derived nutrients on algal production in salmon nursery lakes of Alaska during the past 300 years

Brock

Leavitt

Schindler

et al. 2007

Limnology & Oceanography

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We measured historical changes in sedimentary d 15 N and fossil pigments in four lakes with anadromous semelparous salmon and two reference lakes to quantify the degree to which the flux of marine-derived nutrients (MDNs as N isotopes) regulate algal production (as pigments). During the past 300 yr, production of the predominant algae (diatoms) was positively correlated (r 5 0.42-0.93, p , 0.02) with sedimentary d 15 N in nursery lakes of sockeye salmon (Oncorhynchus nerka) but was inversely correlated with sedimentary d 15 N (r 5 20.71 to 20.73, p , 0.0001) in reference lakes that lacked migratory fishes. Overall, the pigment-d 15 N correlation during the 20th century was strongly correlated with both mean densities of spawning sockeye salmon during 1956-2000 (r 5 0.97, p , 0.002) and the fraction of total ecosystem N derived from salmon during 1900-2000 (r 5 0.98, p , 0.001). Together these patterns suggest that the sign of the d 15 N-pigment correlation can be used to distinguish among lakes or periods of time in which algal production is regulated mainly by MDN influx (positive correlation) or other factors (negative correlation). Tests of this hypothesis revealed that the degree to which MDNs regulated algal production in nursery lakes varied greatly since 1700, with significant periods of weak control even in lakes with abundant salmon. Further, when considered at the landscape scale, the importance of MDNs to individual lakes varied substantially through time and in space, with little evidence of synchrony among sites or catchments.

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“…Thus, salmon move bioavailable nutrients out of streams. Brock et al (2006) found that sediments were slightly enriched with the stable isotope 15 N around the mouth of Pick Creek, evidence of local deposition and retention FIG. Schindler et al (2005) observed that productivity of Lake Nerka was responsive to changes in loading of salmon-derived nutrients.…”

Section: May 2007mentioning

confidence: 94%

Biotic Control of Stream Fluxes: Spawning Salmon Drive Nutrient and Matter Export

Moore

Schindler

Carter

et al. 2007

Ecology

Self Cite

130

132

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Organisms can control movements of nutrients and matter by physically modifying habitat. We examined how an ecosystem engineer, sockeye salmon (Oncorhynchus nerka), influences seasonal fluxes of sediments, nitrogen (N), and phosphorus (P) in streams of southwestern Alaska. The purpose of this study was to investigate whether salmon act as net importers or net exporters of matter and nutrients from streams and how these roles change as a function of salmon population density. We measured discharge and concentrations of suspended sediments and total N and P every 7-14 days for up to four summers in 10 streams spanning a gradient in salmon densities. We statistically allocated whole-season fluxes to salmon activities, such as excretion and bioturbation, and to export by hydrologic discharge. In addition, we used counts of spawning salmon to estimate nutrient and matter imports by salmon to streams. Large seasonal pulses of suspended sediments, P, and N were associated with salmon spawning activities, often increasing export an order of magnitude higher than during pre-salmon levels. Years and streams with more salmon had significantly higher levels of export of sediments and nutrients. In addition, years with higher precipitation had higher background export of P and N. Salmon exported an average of the equivalent of 189%, 60%, and 55% of total matter, P, and N that salmon imported in their bodies. The relative magnitude of export varied; salmon exported more than their bodies imported in 80%, 20%, and 16% across all streams and years for sediments, P, and N, respectively. A bioassay experiment indicated that the P exported by salmon is directly available for use by primary producers in the downstream lake. These results demonstrate that salmon not only move nutrients upstream on large spatial scales via their migration from the ocean and subsequent death, but also redistribute matter and nutrients on finer spatial scales through their spawning activities.

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Spatial variability of stable isotopes and fossil pigments in surface sediments of Alaskan coastal lakes: Constraints on quantitative estimates of past salmon abundance

Cited by 26 publications

References 43 publications

Spatial distribution of diatom and pigment sedimentary records in surface sediments in Doubtful Sound, Fiordland, New Zealand

Spatial distribution of diatom and pigment sedimentary records in surface sediments in Doubtful Sound, Fiordland, New Zealand

Variable effects of marine‐derived nutrients on algal production in salmon nursery lakes of Alaska during the past 300 years

Biotic Control of Stream Fluxes: Spawning Salmon Drive Nutrient and Matter Export

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