The impact of temporal variability in light-climate on time-averaged primary production and a phytoplankton bloom in a well-mixed estuary

2020 ◽  
Vol 436 ◽  
pp. 109287
Author(s):  
Dante M.L. Horemans ◽  
Patrick Meire ◽  
Tom J.S. Cox
Keyword(s):  
Primary Production ◽  
Temporal Variability ◽  
Phytoplankton Bloom ◽  
Light Climate ◽  
The Impact

scholarly journals An estimation of the quantitative impacts of copepod grazing on an under sea-ice spring phytoplankton bloom in western Baffin Bay, Canadian Arctic

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Makoto Sampei ◽  
Louis Fortier ◽  
Patrick Raimbault ◽  
Kohei Matsuno ◽  
Yoshiyuki Abe ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Phytoplankton Bloom ◽  
Grazing Rate ◽  
Grazing Pressure ◽  
Spring Phytoplankton Bloom ◽  
Baffin Bay ◽  
Chl A ◽  
Copepod Grazing ◽  
The Impact

This study aimed to quantify the impact of copepod grazing on the productivity of phytoplankton during an under sea-ice spring phytoplankton bloom (USPB) in western Baffin Bay. To quantify positive and/or negative impacts of copepod grazing on primary production and the interaction between copepod grazing and phytoplankton species, we sampled seawater and zooplankton under the landfast sea ice every 2–3 days between May 24 and July 10, 2016. Samples were analyzed for estimation of primary production, chlorophyll-a (chl-a) concentration, diatom abundance, and copepod fecal pellet (FP) production/grazing rate. Analyses of chl-a concentration, primary production, and FP production/grazing rate revealed clear temporal changes and a mismatch between primary production and copepod consumption. The FP production/grazing rate reached a maximum (9.4/31.2 mg C m–2 d–1) on June 16 before the USPB phase and suddenly decreased to 0.7/2.4 mg C m–2 d–1 on June 21, despite an increase in primary production to 74.0 mg C m–2 d–1. The copepod grazing rate (3.7 mg C m–2 d–1) was low relative to primary production (344.6 mg C m–2 d–1) during the USPB phase (after June 20). While our estimates illustrate that copepod grazing did not limit the maximum daily primary production during the USPB, the low grazing pressure (2% of primary production) may have been an additional contributor to the reduction in total primary productivity at the end of the USPB period due primarily to the low supply of regenerated nitrogen-containing nutrients to drive regenerated production.

scholarly journals The influence of riparian woodland on the spatial and temporal variability of stream water temperatures in an upland salmon stream

2004 ◽  
Vol 8 (3) ◽  
pp. 449-459 ◽  
Author(s):  
I. A. Malcolm ◽  
D. M. Hannah ◽  
M. J. Donaghy ◽  
C. Soulsby ◽  
A. F. Youngson
Keyword(s):  
Thermal Regime ◽  
Temporal Variability ◽  
Heat Budget ◽  
Riparian Forest ◽  
Stream Water ◽  
Spatial And Temporal Variability ◽  
Substantial Impact ◽  
Site Specific ◽  
The Impact ◽  
Riparian Woodland

Abstract. The spatio-temporal variability of stream water temperatures was investigated at six locations on the Girnock Burn (30km2 catchment), Cairngorms, Scotland over three hydrological years between 1998 and 2002. The key site-specific factors affecting the hydrology and climatology of the sampling points were investigated as a basis for physical process inference. Particular emphasis was placed on assessing the effects of riparian forest in the lower catchment versus the heather moorland riparian zones that are spatially dominant in the upper catchment. The findings were related to river heat budget studies that provided process detail. Gross changes in stream temperature were affected by the annual cycle of incoming solar radiation and seasonal changes in hydrological and climatological conditions. Inter-annual variation in these controlling variables resulted in inter-annual variability in thermal regime. However, more subtle inter-site differences reflected the impact of site-specific characteristics on various components of the river energy budget. Inter-site variability was most apparent at shorter time scales, during the summer months and for higher stream temperatures. Riparian woodland in the lower catchment had a substantial impact on thermal regime, reducing diel variability (over a period of 24 hours) and temperature extremes. Observed inter-site differences are likely to have a substantial effect on freshwater ecology in general and salmonid fish in particular. Keywords: temperature, thermal regime, forest, salmon, hydrology, Girnock Burn, Cairngorm

scholarly journals Regional variability of acidification in the Arctic: a sea of contrasts

2014 ◽  
Vol 11 (2) ◽  
pp. 293-308 ◽  
Author(s):  
E. E. Popova ◽  
A. Yool ◽  
Y. Aksenov ◽  
A. C. Coward ◽  
T. R. Anderson
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Atmospheric Co2 ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Regional Variability ◽  
The Arctic Ocean ◽  
The Impact

Abstract. The Arctic Ocean is a region that is particularly vulnerable to the impact of ocean acidification driven by rising atmospheric CO2, with potentially negative consequences for calcifying organisms such as coccolithophorids and foraminiferans. In this study, we use an ocean-only general circulation model, with embedded biogeochemistry and a comprehensive description of the ocean carbon cycle, to study the response of pH and saturation states of calcite and aragonite to rising atmospheric pCO2 and changing climate in the Arctic Ocean. Particular attention is paid to the strong regional variability within the Arctic, and, for comparison, simulation results are contrasted with those for the global ocean. Simulations were run to year 2099 using the RCP8.5 (an Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) scenario with the highest concentrations of atmospheric CO2). The separate impacts of the direct increase in atmospheric CO2 and indirect effects via impact of climate change (changing temperature, stratification, primary production and freshwater fluxes) were examined by undertaking two simulations, one with the full system and the other in which atmospheric CO2 was prevented from increasing beyond its preindustrial level (year 1860). Results indicate that the impact of climate change, and spatial heterogeneity thereof, plays a strong role in the declines in pH and carbonate saturation (Ω) seen in the Arctic. The central Arctic, Canadian Arctic Archipelago and Baffin Bay show greatest rates of acidification and Ω decline as a result of melting sea ice. In contrast, areas affected by Atlantic inflow including the Greenland Sea and outer shelves of the Barents, Kara and Laptev seas, had minimal decreases in pH and Ω because diminishing ice cover led to greater vertical mixing and primary production. As a consequence, the projected onset of undersaturation in respect to aragonite is highly variable regionally within the Arctic, occurring during the decade of 2000–2010 in the Siberian shelves and Canadian Arctic Archipelago, but as late as the 2080s in the Barents and Norwegian seas. We conclude that, for future projections of acidification and carbonate saturation state in the Arctic, regional variability is significant and needs to be adequately resolved, with particular emphasis on reliable projections of the rates of retreat of the sea ice, which are a major source of uncertainty.

scholarly journals Desertification in Forest, Range and Desert Landuses of Tehran Province, Under the Impact of Climate Change

2016 ◽  
Author(s):  
Hadi Eskandari Dameneh ◽  
Moslem Borji ◽  
Hassan Khosravi ◽  
Ali Salajeghe
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Net Primary Production ◽  
Degradation Process ◽  
Early Warning Systems ◽  
Land Uses ◽  
Emission Scenarios ◽  
Desert Ecosystems ◽  
Tehran Province ◽  
The Impact

Abstract. Persistence of widespread degradation in arid and semi-arid region of Iran necessitates using of monitoring and evaluation systems with appropriate accuracy to determine the degradation process and adoption of early warning systems; because after transition from some thresholds, effective reversible function of ecosystems will not be very easy. This paper tries to monitor the degradation and desertification trends in three land uses including range, forest and desert lands affected by climate change in Tehran province for 2000s and 2030s. For assessing climate changes of Mehrabad synoptic stations the data of two emission scenarios including A2 and B2 were used using statistical downscaling techniques and data generated by SDSM model. The index of net primary production resulting from MODIS satellite images was employed as an indicator of destruction from 2001 to 2010. The results showed that temperature is the most effective driver force which alters the net primary production in rangeland, forest and desert ecosystems of Tehran province. On the basis of monitoring findings under real conditions, in the 2000s, over 60 % of rangelands and 80 % of the forests have been below the average production in the province. On the other hand, the long-term average changes of NPP in rangeland and forests indicated the presence of relatively large areas of these land uses with production rate lower than the desert. The results also showed that, assuming the existence of circumstances of each emission scenarios, the desertification status will not improve significantly in the rangelands and forests of Tehran province.

scholarly journals STUDY ON CYCLONE INDUCED PHYTOPLANKTON BLOOM IN THE ARABIAN SEA THROUGH GAP-FREE RECONSTRUCTED CHLOROPHYLL-A DATA

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 1391-1396
Author(s):  
R. Shunmugapandi ◽  
S. Gedam ◽  
A. B. Inamdar
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Arabian Sea ◽  
Phytoplankton Bloom ◽  
Suitable Condition ◽  
Sea Surface ◽  
Cyclone Track ◽  
Chl A ◽  
The Impact

Abstract. Ocean surface phytoplankton responses to the tropical cyclone (TC)/storms have been extensively studied using satellite observations by aggregating the data into a weekly or bi-weekly composite. The reason behind is the significant limitations found in the satellite-based observation is the missing of valid data due to cloud cover, especially at the time of cyclone track passage. The data loss during the cyclone is found to be a significant barrier to efficiently investigate the response of chl-a and SST during cyclone track passage. Therefore it is necessary to rectify the above limitation to effectively study the impact of TC on the chlorophyll-a concentration (chl-a) and the sea surface temperature (SST) to achieve a complete understanding of their response to the TC prevailed in the Arabian Sea. Intending to resolve the limitation mentioned above, this study aims to reconstruct the MODIS-Aqua chl-a, and SST data using Data Interpolating Empirical Orthogonal Function (DINEOF) for all the 31 cyclonic events occurred in the Arabian Sea during 2003-2018 (16 years). Reconstructed satellite retrieved data covering all the cyclonic events were further used to investigate the chl-a and SST dynamics during TC. From the results, the exciting fact has been identified that only two TC over the eastern-AS were able to induce phytoplankton bloom. On investigating this scenario using sea surface temperature, it was disclosed that the availability of nutrients decides the suitable condition for the phytoplankton to proliferate in the surface ocean. Relevant to the precedent criterion, the results witnessed that the 2 TC (Phyan and Ockhi cyclone) prevailed in the eastern AS invoked a suitable condition for phytoplankton bloom. Other TC found to be less provocative either due to less intensity, origination region or the unsuitable condition. Thereby, gap-free reconstructed daily satellite-derived data efficiently investigates the response of bio-geophysical parameters during cyclonic events. Moreover, this study sensitised that though several TC strikes the AS, only two could impact phytoplankton productivity and SST found to highly consistent with the chl-a variability during the cyclone passage.

scholarly journals Spatio-temporal variability of marine primary and export production in three global coupled climate carbon cycle models

2007 ◽  
Vol 4 (3) ◽  
pp. 1877-1921 ◽  
Author(s):  
B. Schneider ◽  
L. Bopp ◽  
M. Gehlen ◽  
J. Segschneider ◽  
T. L. Frölicher ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Temporal Variability ◽  
Satellite Observations ◽  
Future Climate Change ◽  
Nutrient Concentrations ◽  
Ocean Colour ◽  
Coupled Models ◽  
Low Latitude ◽  
Export Production ◽  
The Impact

Abstract. This study compares spatial and temporal variability in net primary productivity (PP) and particulate organic carbon (POC) export production (EP) from three different coupled climate carbon cycle models (IPSL, MPIM, NCAR) with observation-based estimates derived from satellite measurements of ocean colour and inverse modelling. Satellite observations of ocean colour have shown that temporal variability of PP on the global scale is largely dominated by the permanently stratified, low-latitude ocean (Behrenfeld et al., 2006)\\nocite{Behrenfeld06} with stronger stratification (higher SSTs) leading to negative PP anomalies and vice versa. Results from all three coupled models confirm the role of the low-latitude, permanently stratified ocean for global PP anomalies. Two of the models also reproduce the inverse relationship between stratification (SST) and PP, especially in the equatorial Pacific. With the help of the model results we are able to explain the chain of cause and effect leading from stratification (SST) through nutrient concentrations to PP and finally to EP. There are significant uncertainties in observational PP and especially EP. Our finding of a good agreement between independent estimates from coupled models and satellite observations provides increased confidence that such models can be used as a first basis to estimate the impact of future climate change on marine productivity and carbon export.

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