Ecosystem Indicators of Water Quality Part I. Plankton Biomass, Primary Production and Nutrient Demand

Author(s):  
W. Glen Harrison ◽  
Tim Perry ◽  
William K.W. Li
2020 ◽  
Vol 7 (4) ◽  
pp. 169-174
Author(s):  
Chatragadda Ramesh ◽  
Raju Mohanraju

Seagrasses are unique marine flowering plants that play an important ecological role by yielding primary production and carbon sequestration to the marine environment. Seagrass ecosystems are rich in organic matter, supporting the growth of bio-medically important epi and endophytic microorganisms and harbor rich marine biodiversity. They are an essential food source for endangered Andaman state animal Dugongs. Seagrasses are very sensitive to water quality changes, and therefore they serve as ecological bio-indicators for environmental changes. The benthic components in and around the seagrass beds support a significant food chain for other Micro and organisms apart from fishery resources. The epiphytic bacterial communities of the leaf blades support the sustenance against the diseases. Recent reports have shown that the loss of seagrass beds in tropical and temperate regions emphasizes the depletion of these resources, and proper management of seagrass is urgent. The decline of seagrass will impact primary production, biodiversity, and adjacent ecosystems, such as reefs. Therefore, restoring the seagrass meadows could be possible with effective implementing management programs, including seagrass meadows in marine protected areas, restoration projects, seagrass transplantation, implementation of legislative rules, monitoring coastal water quality and human activities in the coastal zone. Lacunas on the seagrass ecosystem management in Andaman & Nicobar Islands are addressed.


2017 ◽  
Vol 78 ◽  
pp. 311-321 ◽  
Author(s):  
József Kovács ◽  
Péter Tanos ◽  
Gábor Várbíró ◽  
Angéla Anda ◽  
Sándor Molnár ◽  
...  

2014 ◽  
Vol 5 (1) ◽  
pp. 18
Author(s):  
Soultana K. Gianniou ◽  
Vassilis Z. Antonopoulos

Primary production and phosphorus are two of the most important determinants of the water quality of lakes. Phytoplankton primary production and phosphorus cycling were modelled within a one-dimensional lake water quality model. The model was calibrated and applied to Lake Vegoritis in Greece for two different years (1981 and 1993) using daily meteorological variables and inflow rates as input data. Monthly profiles of temperature, chlorophyll-a, and oxygen concentration for these two years were used to calibrate the model. Simulation results indicate that the thermal regime of the lake strongly affects phosphorus profiles and that phytoplankton concentrations throughout the year are tightly correlated with soluble reactive phosphorus concentrations. The significant decrease in the depth and the volume of the lake from 1981 to 1993 resulted in important changes in phytoplankton and phosphorus concentrations. A sensitivity analysis was conducted to estimate the errors resulting from the uncertainty in the biochemical variables of the model and the limited data on phosphorus and phytoplankton.


Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3029
Author(s):  
Melissa A. Knapp ◽  
Naomi Geeraert ◽  
Kiho Kim ◽  
Karen L. Knee

Seagrass meadows and coral reefs along the coast of Saipan, a US commonwealth in the Northern Pacific, have been declining since the 1940s, possibly due to nutrient loading. This study investigated whether submarine groundwater discharge (SGD) contributes to nutrient loading and supports primary production on Saipan’s coast. SGD can be an important source of freshwater, nutrients, and other pollutants to coastal waters, especially in oceanic islands without well-developed stream systems. Ra and Rn isotopes were used as natural tracers of SGD. Nitrate, phosphate, and ammonium concentrations, ancillary water quality parameters, δ15N and δ18O of dissolved nitrate, and δ15N of primary producer tissue were measured. Our results pointed to discharge of low-salinity groundwater containing elevated concentrations of sewage-derived N at specific locations along Saipan’s coast. High SGD areas had lower salinity and pH, higher dissolved inorganic nitrogen concentrations, and elevated primary producer δ15N, indicative of sewage nitrogen inputs. We estimated that SGD could support 730–6400 and 3000–15,000 mol C d−1 of primary production in Tanapag and Garapan Lagoons, respectively, or up to approximately 60% of primary production in Garapan Lagoon. Efforts to improve water quality, reduce nutrient loading, and preserve coastal ecosystems must account for groundwater, since our results demonstrate that it is an important pathway of nitrogen delivery.


Author(s):  
Kazuhiro KOMATSU ◽  
Megumi NAKAGAWA ◽  
Kenji TSUCHIYA ◽  
Ayato KOHZU ◽  
Ryuichiro SHINOHARA ◽  
...  

2020 ◽  
Author(s):  
Devanshi Pathak ◽  
Michael Hutchins ◽  
François Edwards

<p>River phytoplankton provide food for primary consumers, and are a major source of oxygen in many rivers. However, high phytoplankton concentrations can hamper river water quality and ecosystem functioning, making it crucial to predict and prevent harmful phytoplankton growth in rivers. In this study, we modify an existing mechanistic water quality model to simulate sub-daily changes in water quality, and present its application in the River Thames catchment. So far, the modelling studies in the River Thames have focused on daily to weekly time-steps, and have shown limited predictive ability in modelling phytoplankton concentrations. With the availability of high-frequency water quality data, modelling tools can be improved to better understand process interactions for phytoplankton growth in dynamic rivers. The modified model in this study uses high-frequency water quality data along a 62 km stretch in the lower Thames to simulate river flows, water temperature, nutrients, and phytoplankton concentrations at sub-daily time-steps for 2013-14. Model performance is judged by percentage error in mean and Nash-Sutcliffe Efficiency (NSE) statistics. The model satisfactorily simulates the observed diurnal variability and transport of phytoplankton concentrations within the river stretch, with NSE values greater than 0.7 at all calibration sites. Phytoplankton blooms develop within an optimum range of flows (16-81 m<sup>3</sup>/s) and temperature (11-18° C), and are largely influenced by phytoplankton growth and death rate parameters. We find that phytoplankton growth in the lower Thames is mainly limited by physical controls such as residence time, light, and water temperature, and show some nutrient limitation arising from phosphorus depletion in summer. The model is tested under different future scenarios to evaluate the impact of changes in climate and management conditions on primary production and its controls. Our findings provide support for the argument that the sub-daily modelling of phytoplankton is a step forward in better prediction and management of phytoplankton dynamics in river systems.</p>


2017 ◽  
Vol 14 (19) ◽  
pp. 4423-4433 ◽  
Author(s):  
Yafei Zhu ◽  
Andrew McCowan ◽  
Perran L. M. Cook

Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.


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