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Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R. | ||||
| Title | CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | 140 | Issue | Pages | 14-25 | |
| Keywords | CALIFORNIA CURRENT ECOSYSTEM; OCEAN CARBON-CYCLE; COASTAL WATERS; FRONTAL ZONE; TIME-SERIES; FLUX; SINKING; SEA; PACIFIC; ZOOPLANKTON | ||||
| Abstract | Estimating interannual variability in carbon export is a key goal of many marine biogeochemical studies. However, due to variations in export mechanisms between regions, generalized models used to estimate global patterns in export often fail when used for intra-regional analysis. We present here a region-specific model of export production for the California Current Ecosystem (CCE) parameterized using intensive Lagrangian process studies conducted during El Niño-Southern Oscillation (ENSO) warm and neutral phases by the CCE Long-Term Ecological Research (LTER) program. We find that, contrary to expectations from prominent global algorithms, export efficiency (e-ratio = export / primary productivity) is positively correlated with temperature and negatively correlated with net primary productivity (NPP). We attribute these results to the substantial horizontal advection found within the region, and verify this assumption by using a Lagrangian particle tracking model to estimate water mass age. We further suggest that sinking particles in the CCE are comprised of a recently-produced, rapidly-sinking component (likely mesozooplankton fecal pellets) and a longer-lived, slowly-sinking component that is likely advected long distances prior to export. We determine a new algorithm for estimating particle export in the CCE from NPP (Export = 0.08 · NPP + 72 mg C m-2 d-1). We apply this algorithm to a two-decade long time series of NPP in the CCE to estimate spatial and interannual variability across multiple ENSO phases. Reduced export during the warm anomaly of 2014-2015 and El Niño 2015-2016 resulted primarily from decreased export in the coastal upwelling region of the CCE; the oligotrophic offshore region exhibited comparatively low seasonal and interannual variability in flux. The model resolves intra-regional patterns of in situ export measurements, and provides a valuable contrast to global export models. | ||||
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| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ rl18 @ | Serial | 984 | ||
| Permanent link to this record | |||||
| Author |
Kelly, T.B.; Goericke, R.; Kahru, M.; Song, H.; Stukel, M.R. | ||||
| Title | CCE II: Spatial and interannual variability in export efficiency and the biological pump in an eastern boundary current upwelling system with substantial lateral advection | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | 140 | Issue | Pages | 14-25 | |
| Keywords | california current ecosystem; coastal waters; flux; frontal zone; ocean carbon-cycle; oceanography; pacific; sea; sinking; time-series; Zooplankton | ||||
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| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1022 | ||
| Permanent link to this record | |||||
| Author |
Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R. | ||||
| Title | CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | 140 | Issue | Pages | 52-62 | |
| Keywords | Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system KeyWords Plus:ZOOPLANKTON FECAL PELLETS; NORTH PACIFIC-OCEAN; CURRENT SYSTEM; SOUTHERN CALIFORNIA; UNDERWATER GLIDERS; CARBON EXPORT; ZONE; CHLOROPHYLL; STABILITY; EQUATIONS | ||||
| Abstract | Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014-2015) followed by an El Nino (2015-2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Nino 2016 – and three cruises during El Ninoneutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, massspecific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention. | ||||
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| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ rl18 @ | Serial | 983 | ||
| Permanent link to this record | |||||
| Author |
Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R. | ||||
| Title | CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | Issue | Pages | |||
| Keywords | Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system | ||||
| Abstract | Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014�2015) followed by an El Niño (2015�2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Niño 2016 � and three cruises during El Niño-neutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, mass-specific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention | ||||
| Address | Deep-Sea Research Part I | ||||
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| Publisher | Place of Publication | Editor | |||
| Language | English | Summary Language | Original Title | ||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 966 | ||
| Permanent link to this record | |||||
| Author |
Morrow, R.M.; Ohman, M.D.; Goericke, R.; Kelly, T.B.; Stephens, B.M.; Stukel, M.R. | ||||
| Title | CCE V: Primary production, mesozooplankton grazing, and the biological pump in the California Current Ecosystem: Variability and response to El Niño | Type | $loc['typeJournal Article'] | ||
| Year | 2018 | Publication | Deep Sea Research Part I: Oceanographic Research Papers | Abbreviated Journal | Deep Sea Research Part I: Oceanographic Research Papers |
| Volume | 140 | Issue | Pages | 52-62 | |
| Keywords | Carbon export; Fecal pellets; Sinking particles; Interannual variability; Net primary productivity; Eastern boundary upwelling system | ||||
| Abstract | Predicting marine carbon sequestration in a changing climate requires mechanistic understanding of the processes controlling sinking particle flux under different climatic conditions. The recent occurrence of a warm anomaly (2014-2015) followed by an El Nino (2015-2016) in the southern sector of the California Current System presented an opportunity to analyze changes in the biological carbon pump in response to altered climate forcing. We compare primary production, mesozooplankton grazing, and carbon export from the euphotic zone during quasi-Lagrangian experiments conducted in contrasting conditions: two cruises during warm years – one during the warm anomaly in 2014 and one toward the end of El Nino 2016 – and three cruises during El Ninoneutral years. Results showed no substantial differences in the relationships between vertical carbon export and its presumed drivers (primary production, mesozooplankton grazing) between warm and neutral years. Mesozooplankton fecal pellet enumeration and phaeopigment measurements both showed that fecal pellets were the dominant contributor to export in productive upwelling regions. In more oligotrophic regions, fluxes were dominated by amorphous marine snow with negligible pigment content. We found no evidence for a significant shift in the relationship between mesozooplankton grazing rate and chlorophyll concentration. However, massspecific grazing rates were lower at low-to-moderate chlorophyll concentrations during warm years relative to neutral years. We also detected a significant difference in the relationship between phytoplankton primary production and photosynthetically active radiation between years: at similar irradiance and nutrient concentrations, productivity decreased during the warm events. Whether these changes resulted from species composition changes remains to be determined. Overall, our results suggest that the processes driving export remain similar during different climate conditions, but that species compositional changes or other structural changes require further attention. | ||||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0967-0637 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1021 | ||
| Permanent link to this record | |||||
| Author |
Stukel, M.R.; Kahru, M.; Benitez-Nelson, C.R.; Décima, M.; Goericke, R.; Landry, M.R.; Ohman, M.D. | ||||
| Title | Using Lagrangian-based process studies to test satellite algorithms of vertical carbon flux in the eastern North Pacific Ocean | Type | $loc['typeJournal Article'] | ||
| Year | 2015 | Publication | Journal of Geophysical Research: Oceans | Abbreviated Journal | J. Geophys. Res. Oceans |
| Volume | 120 | Issue | 11 | Pages | 7208-7222 |
| Keywords | satellite-derived export; carbon export; model algorithms; mesozooplankton grazing; sinking particles; gravitational flux | ||||
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| ISSN | 2169-9275 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ mfield @ | Serial | 113 | ||
| Permanent link to this record | |||||
| Author |
Stukel, M.R.; Kelly, T.B. | ||||
| Title | The carbon: (234) Thorium ratios of sinking particles in the California current ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model | Type | $loc['typeJournal Article'] | ||
| Year | 2019 | Publication | Marine Chemistry | Abbreviated Journal | Marine Chemistry |
| Volume | 212 | Issue | Pages | 1-15 | |
| Keywords | POC concentration; sinking particles.; depth and relationship with water; phytoplankton | ||||
| Abstract | Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon: thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking. | ||||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0304-4203 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1002 | ||
| Permanent link to this record | |||||
| Author |
Stukel, M.R.; Ohman, M.D.; Kelly, T.B.; Biard, T. | ||||
| Title | The Roles of Suspension-Feeding and Flux-Feeding Zooplankton as Gatekeepers of Particle Flux Into the Mesopelagic Ocean in the Northeast Pacific | Type | $loc['typeJournal Article'] | ||
| Year | 2019 | Publication | Frontiers in Marine Science | Abbreviated Journal | Front. Mar. Sci. |
| Volume | 6 | Issue | Pages | ||
| Keywords | biological pump; carbon export; remineralization length scale; mesozooplankton ecology; pteropods; marine biogeochemistry; sinking particles; marine snow | ||||
| Abstract | Zooplankton are important consumers of sinking particles in the ocean's twilight zone. However, the impact of different taxa depends on their feeding mode. In contrast to typical suspension-feeding zooplankton, flux-feeding taxa preferentially consume rapidly sinking particles that would otherwise penetrate into the deep ocean. To quantify the potential impact of two flux-feeding zooplankton taxa [Aulosphaeridae (Rhizaria), and Limacina helicina (euthecosome pteropod)] and the total suspension-feeding zooplankton community, we measured depth-stratified abundances of these organisms during six cruises in the California Current Ecosystem. Using allometric-scaling relationships, we computed the percentage of carbon flux intercepted by flux feeders and suspension feeders. These estimates were compared to direct measurements of carbon flux attenuation (CFA) made using drifting sediment traps and U-238-Th-234 disequilibrium. We found that CFA in the shallow twilight zone typically ranged from 500 to 1000 m mol organic C flux remineralized per 10-m vertical depth bin. This equated to approximately 6-10% of carbon flux remineralized/10 m. The two flux-feeding taxa considered in this study could account for a substantial proportion of this flux near the base of the euphotic zone. The mean flux attenuation attributable to Aulosphaeridae was 0.69%/10 m (median = 0.21%/10 m, interquartile range = 0.04-0.81%) at their depth of maximum abundance (similar to 100 m), which would equate to similar to 10% of total flux attenuation in this depth range. The maximum flux attenuation attributable to Aulosphaeridae reached 4.2%/10 m when these protists were most abundant. L. helicina, meanwhile, could intercept 0.45-1.6% of carbon flux/10 m, which was slightly greater (on average) than the Aulosphaeridae. In contrast, suspension-feeding zooplankton in the mesopelagic (including copepods, euphausiids, appendicularians, and ostracods) had combined clearance rates of 2-81 L m(-3) day(-1) (mean of 19.6 L m(-3) day(-1)). This implies a substantial impact on slowly sinking particles, but a negligible impact on the presumably rapidly sinking fecal pellets that comprised the majority of the material collected in sediment traps. Our results highlight the need for a greater research focus on the many taxa that potentially act as flux feeders in the oceanic twilight zone. | ||||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 2296-7745 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Funding | Approved | $loc['no'] | |||
| Call Number | COAPS @ user @ | Serial | 1066 | ||
| Permanent link to this record | |||||
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