Flow events drive patterns of phytoplankton distribution along a river–estuary–bay continuum

2013 ◽  
Vol 64 (7) ◽  
pp. 655 ◽  
Author(s):  
Emily A. Saeck ◽  
Wade L. Hadwen ◽  
David Rissik ◽  
Katherine R. O'Brien ◽  
Michele A. Burford
Keyword(s):  
Nitrogen Availability ◽  
River Estuary ◽  
High Flow ◽  
Phytoplankton Growth ◽  
Nutrient Loads ◽  
Anthropogenic Pressures ◽  
Phytoplankton Productivity ◽  
Chl A ◽  
Phytoplankton Distribution ◽  
Flow Phase

Freshwater flow events drive phytoplankton productivity in subtropical coastal river systems. However, few studies have the necessary temporal and spatial resolution to fully characterise the effect of events on the distribution of phytoplankton across the full river–estuary–bay continuum. The present study characterised the response of phytoplankton to high-flow events in an Australian subtropical system; and identified the primary drivers of this response. During high-flow events, the concentration of phytoplankton chlorophyll a (Chl a) initially declined in the estuary, a response primarily driven by the shortened water-residence time. In the bay, phytoplankton growth in the near-shore zone was light limited; however, nutrients stimulated phytoplankton growth on the seaward edge of the river plume. During the post-high-flow phase, the concentration of Chl a in the freshwater reaches peaked downstream, where catchment-derived nutrients accumulated. In the estuary, elevated nutrient loads stimulated phytoplankton growth upstream and downstream of the light-limited zone. In the bay, nitrogen availability declined, and Chl a declined with an increasing distance offshore. The phytoplankton response to events documented in the present study can be used to identify when and where phytoplankton in subtropical systems may be strongly influenced by changes in the magnitude of nutrient, sediment and freshwater loads associated with high-flow events which result from anthropogenic pressures within the catchment.

scholarly journals Turbidity maximum zone index: a novel model for remote extraction of the turbidity maximum zone in different estuaries

2021 ◽  
Vol 14 (11) ◽  
pp. 6833-6846
Author(s):  
Chongyang Wang ◽  
Li Wang ◽  
Danni Wang ◽  
Dan Li ◽  
Chenghu Zhou ◽  
...  
Keyword(s):  
Remote Sensing ◽  
River Estuary ◽  
High Flow ◽  
Turbidity Maximum ◽  
Low Flow ◽  
Distribution Area ◽  
Spatial And Temporal Variation ◽  
Chl A ◽  
Turbidity Maximum Zone ◽  
Novel Model

Abstract. An efficient recognition and extraction of the estuarine turbidity maximum zone (TMZ) is important for studying terrestrial hydrological processes. Although many studies relevant to the TMZ have been conducted worldwide, the extraction methods and criteria used to describe the TMZ vary significantly both spatially and temporally. To improve the applicability of the methods adopted in previous studies and to develop a novel model to accurately extract the TMZ in multiple estuaries and different seasons from remote-sensing imageries, this study estimated the total suspended solid (TSS) and chlorophyll a (Chl a) concentrations in three estuaries. These were the Pearl River estuary (PRE), the Hanjiang River estuary (HRE), and the Moyangjiang River estuary (MRE) of Guangdong Province, China. The spatial distribution characteristics of the TSS and Chl a concentrations were analyzed. A nearly opposite association was found between the TSS and Chl a concentrations in the three estuaries, particularly in the PRE. The regions with high (low) TSS concentrations had relatively low (high) Chl a concentrations and, therefore, a turbidity maximum zone index (TMZI), defined as the ratio of the difference and sum of the logarithmic transformation of the TSS and Chl a concentrations, was firstly proposed. By calculating the TMZI values in the PRE on 20 November 2004 (low-flow season), it was found that the criterion TMZI>0.2 could be used to identify the TMZs of the PRE effectively. The TMZ extraction results were generally consistent with the visual-interpretation results. The area-based accuracy measures showed that the quality (Q) of the extraction reached 0.8429. The same criterion was applied in the PRE on 18 October 2015 (high-flow season), and high accuracy and consistency across seasons were observed (Q=0.8171). The western shoal of the PRE was the main distribution area of TMZs. Extracting TMZs by the newly proposed index performed well in different estuaries and on different dates (HRE on 13 August 2008 in the high-flow season and MRE on 6 December 2013 in the low-flow season). Compared to the previous fixed threshold of TSS or turbidity methods, extracting the TMZ using the TMZI had higher accuracy and better applicability (Q: 0.1046–0.4770 vs. 0.8171–0.8429). Evidently, this unified TMZI is potentially an optimized method for the global monitoring and extraction of TMZs of estuaries from different satellite remote-sensing imageries. It can be used to help the understanding of the spatial and temporal variation in TMZs and estuarine processes at regional and global scales as well as improve the management and sustainable development of regional society and the natural environment.

scholarly journals The Role of Environmental Factors on the Fishery Catch of the Squid Uroteuthis chinensis in the Pearl River Estuary, China

2021 ◽  
Vol 9 (2) ◽  
pp. 131
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Sea Surface ◽  
Spatiotemporal Variability ◽  
Pearl River ◽  
Coastal Current ◽  
Catch Per Unit Effort ◽  
Chl A ◽  
The Pearl River Estuary ◽  
The Pearl River

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.

Analysis of within- and between-day chlorophyll-a dynamics in Mantua Superior Lake, with a continuous spectroradiometric measurement

2013 ◽  
Vol 64 (4) ◽  
pp. 303 ◽  
Author(s):  
M. Bresciani ◽  
M. Rossini ◽  
G. Morabito ◽  
E. Matta ◽  
M. Pinardi ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Continuous Monitoring ◽  
Phytoplankton Growth ◽  
Key Factors ◽  
Eutrophic Lakes ◽  
Chl A ◽  
Metabolic Adaptations ◽  
Horizontal Migration ◽  
Radiometric System ◽  
Growth Distribution

Eutrophic lakes display unpredictable patterns of phytoplankton growth, distribution, vertical and horizontal migration, likely depending on environmental conditions. Monitoring chlorophyll-a (Chl-a) concentration provides reliable information on the dynamics of primary producers if monitoring is conducted frequently. We present a practical approach that allows continuous monitoring of Chl-a concentration by using a radiometric system that measures optical spectral properties of water. We tested this method in a shallow, nutrient-rich lake in northern Italy, the Mantua Superior Lake, where the radiometric system collected data all throughout the day (i.e. every 5 min) for ~30 days. Here, specifically developed algorithms were used to convert water reflectance to Chl-a concentration. The best performing algorithm (R2 = 0.863) was applied to a larger dataset collected in September 2011. We characterised intra- and inter-daily Chl-a concentration dynamics and observed a high variability; during a single day, Chl-a concentration varied from 20 to 130 mg m–3. Values of Chl-a concentration were correlated with meteo-climatic parameters, showing that solar radiance and wind speed are key factors regulating the daily phytoplankton growth and dynamics. Such patterns are usually determined by vertical migration of different phytoplankton species within the water column, as well as by metabolic adaptations to changes in light conditions.

scholarly journals Effects of the interaction of ocean acidification, solar radiation, and warming on biogenic dimethylated sulfur compounds cycling in the Changjiang River Estuary

2017 ◽  
Author(s):  
Shan Jian ◽  
Jing Zhang ◽  
Hong-Hai Zhang ◽  
Gui-Peng Yang
Keyword(s):  
Solar Radiation ◽  
Ocean Acidification ◽  
River Estuary ◽  
Sulfur Compounds ◽  
Changjiang River ◽  
Changjiang River Estuary ◽  
Chl A ◽  
The Changjiang River ◽  
Temperature Conditions ◽  
The Changjiang River Estuary

Abstract. Ocean acidification (OA) affects marine primary productivity and community structure, and therefore may influence the biogeochemical cycles of volatile biogenic dimethyl sulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) and photochemical oxidation product dimethyl sulfoxide (DMSO). A 23-day incubation experiment on board was conducted to investigate the short-term response of biogenic sulfur compounds production and cycling to OA in the Changjiang River Estuary and further understand its effects on biogenic sulfur compounds. Result showed that phytoplankton abundance and species presented remarkable differences under three different pH levels in the late stage of the experiment. A significant reduction in chlorophyll a (Chl-a), DMS, particulate DMSP (DMSPp), and dissolved DMSO (DMSOd) concentrations was identified under high CO2 levels. Moreover, minimal change was observed in the production of dissolved DMSP (DMSPd) and particulate DMSO (DMSOp) among treatments. The ratios of DMS, total DMSP (DMSPt), and total DMSO (DMSOt) to Chl-a were also not affected by a change in pH. In addition, DMS and DMSOd were highly related to mean bacterial abundance under three pH levels. Additional incubation experiments on light and temperature showed that the influence of pH on productions of dimethylated sulfur compounds also depended on solar radiation and temperature conditions. DMS photodegradation rate increased with decreasing pH under full-spectrum natural light and UVB light. Thus, OA may lead to decreasing DMS concentrations in the surface seawater. Light and temperature conditions also play an important role in the production and cycling of biogenic sulfur compounds.

scholarly journals The Zrmanja River Estuary (Adriatic Coast, Croatia) – the Need for Interdisciplinary Approach to Protection of Coastal Areas

2018 ◽  
Vol 55 (1) ◽  
pp. 9-32
Author(s):  
Željka Fiket ◽  
Goran Kniewald
Keyword(s):  
Sustainable Use ◽  
River Estuary ◽  
Interdisciplinary Approach ◽  
Karst Area ◽  
Geochemical Data ◽  
Anthropogenic Factors ◽  
Anthropogenic Pressures ◽  
Adriatic Coast ◽  
Enclosed Bay ◽  
Sedimentation Processes

The Zrmanja River estuary is a semi-enclosed bay immersed in a karstic landscape of the eastern Adriatic coast. It represents a highly indented system which includes part of the Zrmanja River, downstream from the Jankovića Buk, the Novigrad and the Karin Seas, and the strait connecting the Novigrad Sea with the Velebit Channel. The very fact that the estuary of the Zrmanja River is located in the karst area makes this system highly vulnerable and susceptible to possible anthropogenic pressures. Preservation of such and similar water systems relies on the knowledge of the main factors that govern its physical, chemical, biological and geochemical features. Due to the lack of geochemical data for the Zrmanja River estuary, a comprehensive study was carried out to explain sedimentation processes and the origin of the material within this estuary and provide additional knowledge necessary for its sustainable use and preservation. This paper, therefore, attempts to summarize the obtained data, focusing on the main natural and anthropogenic factors that define the geochemistry of the Zrmanja River estuary.

scholarly journals MODIS observed phytoplankton dynamics in the Taiwan Strait: an absorption-based analysis

2011 ◽  
Vol 8 (4) ◽  
pp. 841-850 ◽  
Author(s):  
S. Shang ◽  
Q. Dong ◽  
Z. Lee ◽  
Y. Li ◽  
Y. Xie ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Sea Water ◽  
River Estuary ◽  
Taiwan Strait ◽  
Percentage Error ◽  
Nutrient Loads ◽  
Phytoplankton Dynamics ◽  
Average Percentage ◽  
The Taiwan Strait

Abstract. This study used MODIS observed phytoplankton absorption coefficient at 443 nm (Aph) as a preferable index to characterize phytoplankton variability in optically complex waters. Aph derived from remote sensing reflectance (Rrs, both in situ and MODIS measured) with the Quasi-Analytical Algorithm (QAA) were evaluated by comparing them with match-up in situ measurements, collected in both oceanic and nearshore waters in the Taiwan Strait (TWS). For the data with matching spatial and temporal window, it was found that the average percentage error (ε) between MODIS derived Aph and field measured Aph was 33.8% (N=30, Aph ranges from 0.012 to 0.537 m−1), with a root mean square error in log space (RMSE_log) of 0.226. By comparison, ε was 28.0% (N=88, RMSE_log = 0.150) between Aph derived from ship-borne Rrs and Aph measured from water samples. However, values of ε as large as 135.6% (N=30, RMSE_log = 0.383) were found between MODIS derived chlorophyll-a (Chl, OC3M algorithm) and field measured Chl. Based on these evaluation results, we applied QAA to MODIS Rrs data in the period of 2003–2009 to derive climatological monthly mean Aph for the TWS. Three distinct features of phytoplankton dynamics were identified. First, Aph is low and the least variable in the Penghu Channel, where the South China Sea water enters the TWS. This region maintains slightly higher values in winter (~17% higher than that in the other seasons) due to surface nutrient entrainment under winter wind-driven vertical mixing. Second, Aph is high and varies the most in the mainland nearshore water, with values peaking in summer (June–August) when river plumes and coastal upwelling enhance surface nutrient loads. Interannual variation of bloom intensity in Hanjiang River estuary in June is highly correlated with alongshore wind stress anomalies, as observed by QuikSCAT. The year of minimum and maximum bloom intensity is in the midst of an El Niño and a La Niña event, respectively. Third, a high Aph patch appears between April and September in the middle of the southern TWS, corresponding to high thermal frontal probabilities, as observed by MODIS. Our results support the use of satellite derived Aph for time series analyses of phytoplankton dynamics in coastal ocean regions, whereas satellite Chl products derived empirically using spectral ratio of Rrs suffer from artifacts associated with non-biotic optically active materials.

scholarly journals Response to Environmental Factors of Spawning Ground in the Pearl River Estuary, China

2021 ◽  
Vol 9 (7) ◽  
pp. 763
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen ◽  
Ruirui Hu
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Sea Surface ◽  
Spatiotemporal Variability ◽  
Pearl River ◽  
Spawning Ground ◽  
Spawning Grounds ◽  
Chl A ◽  
The Pearl River Estuary ◽  
The Pearl River

Spawning grounds are important areas for fish survival and reproduction, and play a key role in the supplement of fishery resources. This study investigated environmental effects on the spatiotemporal variability of spawning ground in the Pearl River Estuary (PRE), China, using the generalized additive model (GAM), based on satellite remote sensing (sea surface temperature (SST), chlorophyll-a concentration (Chl-a), sea surface salinity (SSS), depth), and in situ observations. Results showed that 39.8% of the total variation in fish egg density was explained by these factors. Among them, the most important factor was SST, accounting for 14.3%, followed by Depth, SSS, and Chl-a, with contributions of 9.7%, 8.5%, and 7.3%, respectively. Spawning grounds in the PRE were mainly distributed in the waters with SST of 22 °C, depth of 30–50 m, SSS of 16–35 ‰, and Chl-a of 6–15 mg/m3. From spring to summer, the spawning ground moved from the outlet of the PRE to the east. The distribution of the spawning ground in the PRE was mainly affected by the Pearl River Plume (PRP), Guangdong Coastal Current (GCC), and monsoons in this area.

Principal Component Analysis of Eutrophication in the Yangtze River Estuary

2012 ◽  
Vol 209-211 ◽  
pp. 1910-1914
Author(s):  
Qiang An ◽  
Lu Lin ◽  
Yuan Yuan Liu ◽  
Ning Qiu Huang ◽  
Bin Zhao
Keyword(s):  
Principal Component Analysis ◽  
Yangtze River ◽  
River Estuary ◽  
Principal Component ◽  
Component Analysis ◽  
Yangtze River Estuary ◽  
Adjacent Area ◽  
The Yangtze River ◽  
Chl A ◽  
The Yangtze River Estuary

The Yangtze River Estuary has become increasingly challenged by various destructive threats to its ecosystem such as the frequent occurrence of harmful algal blooms. Four cruises were carried out in the Yangtze River Estuary and its adjacent area in 2006. Ten variables including CODMn, PO43--P, SiO3-Si, NO3--N, NO2--N, NH4+-N, TN, TP, TOC and chl-a were analyzed by exploratory data analysis. Nitrate was the dominant form of TN throughout the year. Principal component analysis (PCA) was applied to estimate the sources of nutrients contamination in 2006. Two principal components (PCs) were extracted, namely, CODMn, PO43--P, NO3--N and TN for PC1, NO2--N and chl-a for PC2. Influenced by anthropogenic sewage, PC1 near Shidongkou, Bailonggang, Xinhe and Zhuyuan outlets was higher than other stations. The primary influencing factor of PC1 were the contaminants carried by runoff from the Yangtze River. And the dominating factors of eutrophication in 2006 were CODMn, PO43--P, NO3--N, TN and chl-a in the Yangtze River Estuary and its adjacent area.

scholarly journals Phytoplankton growth and physiological responses to a plume front in the northern South China Sea

2017 ◽  
Author(s):  
Qian P. Li ◽  
Weiwen Zhou ◽  
Yinchao Chen ◽  
Zhengchao Wu
Keyword(s):  
South China Sea ◽  
South China ◽  
Bottom Water ◽  
Frontal Zone ◽  
Northern South China Sea ◽  
River Estuary ◽  
Phytoplankton Growth ◽  
Frontal System ◽  
China Sea ◽  
Plume Water

Abstract. Due to a strong river discharge during April–June 2016, a persistent salinity front, with freshwater flushing seaward on the surface but seawater moving landward at the bottom, was formed in the coastal waters west of the Pearl River Estuary (PRE) over the Northern South China Sea (NSCS) shelf. Hydrographic measurements revealed that the salinity front was influenced by both river plume and coastal upwelling. Shipboard nutrient-enrichment experiments with size-fractionation chlorophyll-a measurements were performed on both sides of the front as well as the front zone to diagnose the spatial variations of phytoplankton physiology across the frontal system. We also assessed the size-fractionated responses of phytoplankton to the treatment of plume water at the frontal zone and the seaside of the front. Biological impact of vertical mixing or upwelling was further examined by the response of surface phytoplankton to the addition of local bottom water. Our results suggested that there was a large variation of phytoplankton physiology on the seaside of the front driven by dynamic nutrient fluxes, although P-limitation was prevailing on the shore-side of the front and at the frontal zone. The spreading of plume water at the frontal zone would directly improve the growth of micro-phytoplankton, while nano- and pico-phytoplankton growths could become saturated at high percentages of plume water. Also, the mixing of bottom water would stimulate the growth of surface phytoplankton on both sides of the front by altering the surface N / P ratio closer to the Redfield stoichiometry. In summary, phytoplankton growth and physiology could be profoundly influenced by physical dynamics of the frontal system during the spring–summer of 2016.

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