Spectral Analysis of Zooplankton Spatial Heterogeneity

Mackas, David L.; Boyd, Carl M.

doi:10.1126/science.204.4388.62

Cited by 139 publications

(82 citation statements)

References 7 publications

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“…This lack of correspondence between export flux and NPP may also be caused by spatial variability in export that operates on smaller spatial scales than that for phytoplankton pigment concentrations or NPP. Evidence of this can be found in the literature (e.g., Mackas and Boyd, 1979;Abraham, 1998) assuming that 234 Th scavenging and particle export flux varies on the same spatial scales as zooplankton abundance in the euphotic zone. This is conceivable as zooplankton create export through their production of fecal pellets and as the packagers of marine snow (e.g., Alldredge and Silver, 1988).…”

Section: Variability In Particle Flux and Attenuationmentioning

confidence: 79%

“…This is conceivable as zooplankton create export through their production of fecal pellets and as the packagers of marine snow (e.g., Alldredge and Silver, 1988). Observations and numerical experiments generally show power spectra for phytoplankton abundance that have redder (steeper) wavenumber spectra than do zooplankton distributions (e.g., Mackas and Boyd, 1979;Tsuda et al, 1993;Abraham, 1998 -though counter examples have been discussed by Martin and Srokosz, 2002). This means that more of the variance in phytoplankton concentrations is contained on larger scales than for zooplankton abundances and presumably for export and 234 Th flux.…”

Section: Variability In Particle Flux and Attenuationmentioning

confidence: 99%

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Thorium-234 as a tracer of spatial, temporal and vertical variability in particle flux in the North Pacific

Buesseler

Pike

Maiti

et al. 2009

Deep Sea Research Part I: Oceanographic Research Papers

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An extensive 234 Th data set was collected at two sites in the North Pacific: ALOHA, an oligotrophic site near Hawaii, and K2, a mesotrophic HNLC site in the NW Pacific as part of the VERTIGO (VERtical Transport in the Global Ocean) study. Total 234 Th:238 U activity ratios near 1.0 indicated low particle fluxes at ALOHA, while 234 Th: 238 U ~0.6 in the euphotic zone at K2 indicated higher particle export. However, spatial variability was large at both sites-even greater than seasonal variability as reported in prior studies. This variability in space and time confounds the use of single profiles of 234 Th for sediment trap calibration purposes. At K2, there was a decrease in export flux and increase in 234 Th activities over time associated with the declining phase of a summer diatom bloom, which required the use of non-steady state models for flux predictions. This variability in space and time confounds the use of single profiles of 234 Th for sediment trap calibration purposes. High vertical resolution profiles show narrow layers (20-30 m) of excess 234 Th below the deep chlorophyll maximum at K2 associated with particle remineralization resulting in a decrease in flux at depth that may be missed with standard sampling for 234 Th and/or with sediment traps. Also, the application of 234 Th as POC flux tracer relies on accurate sampling of particulate POC/ 234 Th ratios and here the ratio is similar on sinking particles and mid-sized particles collected by in-situ filtration (>10-50 µm at ALOHA and >5-350 µm at K2). To further address variability in particle fluxes at K2, a simple model of the drawdown of 234 Th and nutrients is used to demonstrate that while coupled during export, their ratios in the water column will vary with time and depth after export. Overall these 234 Th data provide a detailed view into particle flux and remineralization in the North Pacific over time and space scales that are varying over days to weeks, and 10's to 100's km at a resolution that is difficult to obtain with other methods.

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Section: Variability In Particle Flux and Attenuationmentioning

confidence: 79%

Section: Variability In Particle Flux and Attenuationmentioning

confidence: 99%

Thorium-234 as a tracer of spatial, temporal and vertical variability in particle flux in the North Pacific

Buesseler

Pike

Maiti

et al. 2009

Deep Sea Research Part I: Oceanographic Research Papers

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“…Seabirds forage in an environment where physical processes depend on scale (Stommel 1963) and where biological and physical processes interact to impart scale-dependent spatial structure to planktonic biomass (Platt 1972, Mackas & Boyd 1979. Scaledependent response by birds to hydrographic structuring of marine ecosystems is suggested by the fact that bird aggregations on the order of 10 to 50 km in lateral extent have been reported along transects normal to hydrographic features in the California Current (Briggs et al 1984) and in the Bering Sea (Schneider 1982, Kinder et al 1983, Woodby 1984.…”

Section: Introductionmentioning

confidence: 99%

Scale-dependent variability in seabird abundance

Schneider¹,

Duffy²

1985

Mar. Ecol. Prog. Ser.

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Patchiness of CO-occurring species of seabirds in an anisotropically structured physical regime was investigated by making continuous counts of birds along 4 transects in the Benguela upwelling region, in the southeastern Atlantic Ocean. Birds were highly aggregated at spatial scales ranging from 0.3 to 23 km. This variability could not be modeled by standard statistical distributions, including negative binomial and gamma distributions. Patchiness was scale-dependent, as indicated by significant changes in moment ratios with change in frame size (measurement interval). Patchiness was not isotropic (independent of transect orientation). Extensive aggregation was observed in 3 out of 5 abundant species along an east-west transect, but was not found in any of these 5 species along a north-south transect. Extensive aggregation was observed in 4 of the same 5 species when the east-west transect was repeated on the following day. Patch scale along the east-west transect ranged from 6.8 to 20.5 km on the first passage. and from 11.5 to 23 km on the second passage. Variation In patch size among species along the same transect indicates that patch scale in seabirds depends on speciesspecific responses to the pelagic environment.

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“…Previous studies have documented zooplankton-phytoplankton interactions through correlation analysis, but the trophic consequences of such interactions were not quantified (Mackas and Boyd 1979;Star and Mullin 1981;Malone and McQueen 1983). Studies have also shown that zooplankton spatial patterns can differ depending on body size (Martin and Srokosz 2002), especially if these patterns are wind-driven (Blukacz et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Evaluating the effect of wind‐driven patchiness on trophic interactions between zooplankton and phytoplankton

Blukacz

Sprules

Shuter

et al. 2010

Limnology & Oceanography

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We measured spatial patterns of zooplankton and chlorophyll concentration (a proxy for phytoplankton) with continuous sensors along horizontal transects that were repeatedly sampled (n 5 150) under varying wind conditions throughout a growing season in two basins (South Arm and Annie Bay) of Lake Opeongo, Ontario, Canada. Spatially explicit in situ simulations that included activity costs associated with feeding were used to examine the effects of chlorophyll patchiness on the energy gain in different zooplankton communities. Simulations were repeated for several zooplankton size classes (small, large, and bulk) and two communities (all copepods and all cladocerans). For each simulated combination, a spatial energetic differential (SED) was estimated by contrasting the energy that zooplankton could gain using observed spatial patterns in chlorophyll and water temperature with the energy they could gain using uniform concentrations of chlorophyll and water temperature. Large zooplankton showed the greatest SED range across all communities, from a decrease of 8% to a maximum increase of 20%, assuming relatively low costs associated with feeding activity. Small zooplankton had the narrowest SED range. Zooplankton energy gain is sensitive to both the degree of zooplanktonchlorophyll spatial overlap and energetic costs associated with zooplankton feeding activity. SED values as high as 485% can occur under plausible estimates of activity costs. Wind-driven increases in spatial overlap between predator and prey can be large enough to substantially alter planktonic trophic interactions.In marine and freshwater ecosystems, both phytoplankton and zooplankton have patchy distributions that occur over a wide range of spatiotemporal scales. Although there is general agreement that the predominant drivers of spatial heterogeneity in phytoplankton distributions are physical (e.g., wind-driven currents), the relative importance of physical vs. biological drivers for zooplankton spatial distributions has been the subject of more debate (Martin 2003). Recent work is shifting this view by demonstrating that physical drivers, by themselves, are insufficient to explain the observed spatial structure across all scales (Martin 2003). The ''multiple driving forces hypothesis '' (Pinel-Alloul 1995) contends that physical drivers have strong control of zooplankton patchiness at large scales, but that the strength of biological drivers increases at small scales.Zooplankton play an important role in trophic interactions as they prey on phytoplankton and serve as food for fish. To gain a better understanding of such interactions, many researchers have used computer simulations (Martin 2003). Most simulations to date have estimated predator (zooplankton) consumption using statistical distributions, rather than observed data, to generate the predator patchiness, the prey (phytoplankton) patchiness, or both (Martin 2003). A few studies have computed consumption directly from observed data (Mullin and Brooks 1976; Sprules 2000). Mull...

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Spectral Analysis of Zooplankton Spatial Heterogeneity

Cited by 139 publications

References 7 publications

Thorium-234 as a tracer of spatial, temporal and vertical variability in particle flux in the North Pacific

Thorium-234 as a tracer of spatial, temporal and vertical variability in particle flux in the North Pacific

Scale-dependent variability in seabird abundance

Evaluating the effect of wind‐driven patchiness on trophic interactions between zooplankton and phytoplankton

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