Water column dissolved silica concentration limits microphytobenthic primary production in intertidal sediments

2019 ◽  
Vol 55 (3) ◽  
pp. 625-636 ◽  
Author(s):  
Julio Bohórquez ◽  
Danielle Calenti ◽  
Emilio García‐Robledo ◽  
Sokratis Papaspyrou ◽  
Juan Luis Jimenez‐Arias ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Intertidal Sediments ◽  
Dissolved Silica ◽  
Silica Concentration ◽  
Concentration Limits

Seasonal variation of water-column light utilization efficiency for primary production in Saroma-ko Lagoon

2021 ◽  
pp. 1-9
Author(s):  
Akihiro Shiomoto ◽  
Yushi Kamuro
Keyword(s):  
Seasonal Variation ◽  
Primary Production ◽  
Water Column ◽  
Fresh Water ◽  
Utilization Efficiency ◽  
Commercial Activity ◽  
The Sustainable Development ◽  
Light Utilization Efficiency ◽  
Light Utilization ◽  
Sunlight Intensity

Abstract In Saroma-ko Lagoon, where scallop aquaculture is a thriving commercial activity, monitoring primary production is essential for determining the amount of scallops that can be farmed. Using the primary production data obtained so far, we calculated Ψ, an index of water-column light utilization efficiency, and clarified its seasonal variation. Ψ tended to be lower in the spring bloom season (February–April), and higher in the late autumn to winter (October–December). Low chlorophyll-normalized production, an index of growth rate, resulted in lower values, while low daily irradiance resulted in higher values. The values of Ψ from our study had a range of 0.05–1.42 gC gChl-a−1 mol photons−1 m2 (N = 56). These values were within the previously reported range of 0.07–1.92 (gC gChl-a−1 mol photons−1 m2) for seawater and fresh water worldwide. Therefore, it is likely that Ψ varies from 0.05–2 gC gChl-a−1 mol photons−1 m2, being affected by conditions of phytoplankton growth and sunlight intensity, regardless of whether samples are collected from seawater or fresh water. Using the median Ψ value of 0.45 gC gChl-a−1 mol photons−1 m2 obtained in this study, primary production was 0.3–3.5 times the actual production at Saroma-ko Lagoon. Using this method, primary production can be easily and constantly monitored, facilitating the sustainable development of scallop aquaculture.

scholarly journals Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin

2015 ◽  
Vol 12 (5) ◽  
pp. 1561-1583 ◽  
Author(s):  
M. Hagens ◽  
C. P. Slomp ◽  
F. J. R. Meysman ◽  
D. Seitaj ◽  
J. Harlay ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Primary Production ◽  
Water Column ◽  
Bottom Water ◽  
Substantial Reduction ◽  
Buffering Capacity ◽  
Total Alkalinity ◽  
Acid Base ◽  
Data Set ◽  
Ph Fluctuations

Abstract. Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity in any hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands). Monthly water-column chemistry measurements were complemented with estimates of primary production and respiration using O2 light–dark incubations, in addition to sediment–water fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA). The resulting data set was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air–sea exchange), but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale). In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment–water exchange), but stronger pH fluctuations (0.60 units). This marked difference in pH dynamics could be attributed to a substantial reduction in the acid–base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid–base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.

scholarly journals The silica-carbon biogeochemical cycle in the Bohai Sea and its responses to the changing terrestrial loadings

2016 ◽  
Author(s):  
Jun Liu ◽  
Lex Bouwman ◽  
Jiaye Zang ◽  
Chenying Zhao ◽  
Xiaochen Liu ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Yellow Sea ◽  
Bohai Sea ◽  
Critical Role ◽  
The Yellow Sea ◽  
Organic C ◽  
Riverine Input ◽  
The Bohai Sea ◽  
River Loads

Abstract. Silicon (Si) and carbon (C) play key roles in the river and marine biogeochemistry. The Si and C budgets for the Bohai Sea were established on the basis of measurements at a range of stations and additional data from the literature. The results show that the spatial distributions of reactive Si and organic C (OC) in the water column are largely affected by the riverine input, primary production and export to the Yellow Sea. Biogenic silica (BSi) and total OC in sediments are mainly from marine primary production. The major supply of dissolved silicate (DSi) comes from benthic diffusion, riverine input alone accounts for 17 % of reactive Si inputs to the Bohai Sea; the dominant DSi removal from the water column is diatom uptake, followed by sedimentation. Rivers contribute 47 % of exogenous OC inputs to the Bohai Sea; the dominant outputs of OC are sedimentation and export to the Yellow Sea. The net burial of BSi and OC represent 3.3 % and 1.0 % of total primary production, respectively. Primary production has increased by 10 % since 2002 as a result of increased river loads of DSi and BSi. Our findings underline the critical role of riverine Si supply in primary production in coastal marine ecosystems.

Vertical Variability of Primary Production and Chlorophyll a in the Kara Sea in the Middle of Summer: Contribution of Subsurface Maxima to the Water Column Values

Oceanology ◽  
2021 ◽  
Vol 61 (5) ◽  
pp. 645-661
Author(s):  
A. B. Demidov ◽  
V. I. Gagarin ◽  
E. V. Eremeeva ◽  
V. A. Artemiev ◽  
A. A. Polukhin ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Chlorophyll A ◽  
Kara Sea ◽  
Vertical Variability

Primary Productivity of Southern Indian Lake before, during, and after Impoundment and Churchill River Diversion

1984 ◽  
Vol 41 (4) ◽  
pp. 591-604 ◽  
Author(s):  
R. E. Hecky ◽  
S. J. Guildford
Keyword(s):  
Light Intensity ◽  
Primary Production ◽  
Water Column ◽  
Primary Productivity ◽  
Phosphorus Deficiency ◽  
Light Environment ◽  
Phytoplankton Production ◽  
Light Penetration ◽  
The Mean ◽  
Chlorophyll Concentrations

The primary productivity of seven regions of Southern Indian Lake and neighboring Wood Lake was measured during open-water seasons from 1974 to 1978. The lake had regional differences in chlorophyll concentrations and daily rates of integral primary production in 1974 and 1975 prior to impoundment of the lake. Regions receiving Churchill River flow tended to have higher chlorophyll concentrations and production rates than those regions marginal to the flow. Impoundment of the lake resulted in higher efficiencies of primary production in all regions, as indicated by higher light-saturated rates of carbon uptake per unit chlorophyll and by higher initial slopes of the hyperbolic light response relation of the phytoplankton. Many large basins of the lake had light penetration reduced by high concentrations of suspended sediment from eroding shorelines, while other areas had relatively unchanged light penetration. The increased efficiency of carbon fixation per unit chlorophyll resulted in higher rates of integral production in those regions where light penetration was not greatly affected. Daily rates of integral primary production in lake regions where light penetration had decreased markedly were not significantly different after impoundment because efficiencies of light utilization were higher. Comparison of the mean water column light intensities for those turbid regions with the values of Ik (light intensity at the onset of light saturation) for phytoplankton indicated that these turbid regions are now light deficient on average. Phosphorus deficiency, as indicated by alkaline phosphatase activity per unit ATP, which was present before impoundment, has been eliminated as the mean water column light intensity declined below 5 mEinsteins∙m−2∙min−1. The light environment of a new reservoir can be a significant determinant of integral production, and predicting the consequences of impoundment on phytoplankton production requires accurate prediction of the light environment.

The effect of dissolved silica on the action of hydrolysing metal coagulants

1998 ◽  
Vol 38 (6) ◽  
pp. 113-120 ◽  
Author(s):  
J. Gregory ◽  
J. Duan
Keyword(s):  
Metal Ions ◽  
Electrophoretic Mobility ◽  
Silicic Acid ◽  
Optical Technique ◽  
Solution Ph ◽  
Dissolved Silica ◽  
Coagulation Process ◽  
Silica Concentration

Using a simple continuous optical technique, coupled with measurements of electrophoretic mobility, the effect of silicic acid or dissolved silica on the coagulation of kaolin suspensions has been examined. The results show that the presence of dissolved silica greatly affects the coagulation process at both low and high coagulant concentrations. The effect depends on the silica concentration and solution pH. Dissolved silica can improve, suppress or even prevent coagulation, and these effects may be due to the modification of hydrolysis species and precipitates due to the interaction between the metal ions and dissolved silica.

Nitrogen, Phosphorus, and Organic Carbon Cycling in an Arctic Lake

1985 ◽  
Vol 42 (4) ◽  
pp. 797-808 ◽  
Author(s):  
S. C. Whalen ◽  
J. C. Cornwell
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Water Column ◽  
Cold Water ◽  
Nutrient Retention ◽  
Overlying Water ◽  
Organic C ◽  
Outlet Stream ◽  
Organic Carbon Cycling ◽  
Nitrogen Phosphorus

Budgets for nitrogen, phosphorus, and organic carbon in Toolik Lake, Alaska, were assembled from data collected during 1977–81. The annual total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) loads to the Sake were 8557, 290, and 4.64 mmol∙m−2. Inlet streams were the major source of nutrients to the lake, as direct precipitation provided only 1, 2, and 5%, respectively, of the annual TOC, TN, and TP loads to the lake. Up to 30% of the annual N and P inputs to the lake from riverine sources occurred during the first 10 d of stream flow following breakup when cold water temperatures and snow-covered ice limited primary production. Due to the short water renewal time (0.5 yr), efficiency of nutrient retention was poor and 90, 82, and 70% of the annual TOC, TN, and TP inputs to the lake were discharged at the outlet stream. Regeneration within the water column supplied 40–66% and 68–78% of the N and P necessary for measured primary production. Yearly accumulation rates for C, N, and P in the sediment were about 220, 21.0, and 1.75 mmol∙m−2. Phosphorus remineralized within the sediment was completely retained due to adsorption onto Fe oxide minerals in the oxidizing surface layer. Annual rates of release of C and N to the overlying water column were 110 and 11.5–22.2 mmol∙m2. Mass balance considerations showed no serious errors in estimates of any terms of the annual sediment and water column N, P, and organic C budgets.

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