Spatial Heterogeneity of Water Quality in a Highly Degraded Tropical Freshwater Ecosystem

2008 ◽  
Vol 43 (2) ◽  
pp. 249-263 ◽  
Author(s):  
Luis Zambrano ◽  
Victoria Contreras ◽  
Marisa Mazari-Hiriart ◽  
Alba E. Zarco-Arista
Keyword(s):  
Water Quality ◽  
Spatial Heterogeneity ◽  
Freshwater Ecosystem ◽  
Tropical Freshwater

scholarly journals Interannual and Spatial Variability of Cyanotoxins in the Prespa Lake Area, Greece

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 357
Author(s):  
Valentini Maliaka ◽  
Miquel Lürling ◽  
Christian Fritz ◽  
Yvon J.M. Verstijnen ◽  
Elisabeth J. Faassen ◽  
...  
Keyword(s):  
Water Quality ◽  
Spatial Variability ◽  
Spatial Heterogeneity ◽  
Dry Weight ◽  
Ecosystem Functions ◽  
Lake Area ◽  
Total Chlorophyll ◽  
Tissue Samples ◽  
Cyanobacteria Blooms ◽  
Prespa Lake

The Prespa Lakes area in Greece—comprised partly of lake Great and lake Lesser Prespa and the Vromolimni pond—has a global importance for biodiversity. Although the waters show regular cyanobacteria blooms, assessments of water quality threats are limited. Samples collected in 2012 revealed scattered and low microcystin (MC) concentrations in Great Prespa (<0.2 μg MC L−1) whereas considerable spatial heterogeneity in both total chlorophyll (2.4–93 µg L−1) and MC concentrations (0.04–52.4 µg MC L−1) was detected in Lesser Prespa. In 2013, there was far less spatial variability of MC concentrations in Lesser Prespa (0.4–1.53 µg L−1), however in 2014, increased concentrations were detected near the lakeshore (25–861 µg MC L−1). In Vromolimni pond the MC concentrations were on average 26.6 (±6.4) µg MC L−1 in 2012, 2.1 (±0.3) µg MC L−1 in 2013 and 12.7 (±12.5) µg MC L−1 in 2014. In 2013, no anatoxins, saxitoxins, nor cylindrospermopsins were detected in Lesser Prespa and Vromolimni waters. Tissue samples from carps, an otter and Dalmatian Pelicans contained 0.4–1.9 µg MC g−1 dry weight. These results indicate that cyanotoxins could be a threat to the ecosystem functions of particularly Lesser Prespa and Vromolimni.

scholarly journals Assessment of Water Quality and Thermal Stress for an Artificial Fish Shelter in an Urban Small Pond during Early Summer

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 139
Author(s):  
Chang Hyuk Ahn ◽  
Saeromi Lee ◽  
Ho Myeon Song ◽  
Jae Roh Park ◽  
Jin Chul Joo
Keyword(s):  
Water Quality ◽  
Thermal Stress ◽  
Water Temperature ◽  
Open Space ◽  
Phenomenological Study ◽  
Quality Parameters ◽  
Early Summer ◽  
Freshwater Ecosystem ◽  
Artificial Wetlands ◽  
Forced Circulation

: This study evaluated water quality variations in an artificial deep pool (ADP), which is an underground artificial structure built in a shallow pond as a fish shelter. The water temperature, pH, dissolved oxygen (DO), and electrical conductivity (EC) were measured on an hourly basis in the open space and inside the ADP, and a phenomenological study was performed, dividing seasons into normal and rainy seasons and environments into stagnant and circulating conditions. The results showed that the water quality parameters inside the ADP exhibit lower fluctuations and diurnal variations compared with the open space. On average, the water temperature inside the ADP is lower than outside it by 1.7–3.7 °C in stagnant conditions, and by 0.6–0.7 °C in circulating conditions during early summer. Thermal stratification occurs inside the ADP but is temporarily disturbed due to the mixing from the forced circulation and the rainwater input through rainfall events. The ADP provided a constant and optimal water temperature for living and spawning for bitterling (i.e., 15.0–21.0 °C), which dominated in experimental pond during spring to summer. Most importantly, the ADP was able to significantly reduce the thermal stress of the fish in the study site, and as a result, the bitterling, a cool water fish species, could successfully become dominant. Finally, the deployment of the ADP appears to provide a practical alternative for effective fishery resources management to improve species diversity and fish communities in an artificial freshwater ecosystem (garden pond, park pond, other artificial wetlands, etc.).

scholarly journals Scavenging by threatened turtles regulates freshwater ecosystem health during fish kills

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia Santori ◽  
Ricky-John Spencer ◽  
Michael B. Thompson ◽  
Camilla M. Whittington ◽  
Thomas H. Burd ◽  
...  
Keyword(s):  
Water Quality ◽  
Ecosystem Health ◽  
Freshwater Ecosystems ◽  
Freshwater Ecosystem ◽  
Freshwater Species ◽  
Freshwater Turtles ◽  
Fish Kills ◽  
Murray Darling Basin ◽  
Ecological Implications ◽  
Mesocosm Experiments

Abstract Humans are increasing the frequency of fish kills by degrading freshwater ecosystems. Simultaneously, scavengers like freshwater turtles are declining globally, including in the Australian Murray–Darling Basin. Reduced scavenging may cause water quality problems impacting both ecosystems and humans. We used field and mesocosm experiments to test whether scavenging by turtles regulates water quality during simulated fish kills. In the field, we found that turtles were important scavengers of fish carrion. In mesocosms, turtles rapidly consumed carrion, and water quality in mesocosms with turtles returned to pre-fish kill levels faster than in turtle-free controls. Our experiments have important ecological implications, as they suggest that turtles are critical scavengers that regulate water quality in freshwater ecosystems. Recovery of turtle populations may be necessary to avoid the worsening of ecosystem health, particularly after fish kills, which would have devastating consequences for many freshwater species.

scholarly journals Challenges in Using Hydrology and Water Quality Models for Assessing Freshwater Ecosystem Services: A Review

Geosciences ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 45 ◽  
Author(s):  
Thibault Hallouin ◽  
Michael Bruen ◽  
Mike Christie ◽  
Craig Bullock ◽  
Mary Kelly-Quinn
Keyword(s):  
Water Quality ◽  
Ecosystem Services ◽  
Freshwater Ecosystem ◽  
Quality Models ◽  
Water Quality Models

Aquaculture impacts on the algal and bacterial communities in a small boreal forest lakeThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1936-1948 ◽  
Author(s):  
David L. Findlay ◽  
Cheryl L. Podemski ◽  
Susan E.M. Kasian
Keyword(s):  
Water Quality ◽  
Nutrient Loading ◽  
Stocking Density ◽  
Freshwater Ecosystem ◽  
Experimental Lakes Area ◽  
Fish Food ◽  
Total N ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Northwestern Ontario ◽  
The Impact

A whole-lake experiment to examine the impacts of aquaculture on a freshwater ecosystem was conducted at the Experimental Lakes Area in northwestern Ontario, Canada. From 2003 to 2006, a 10 tonne fish capacity aquaculture cage stocked with rainbow trout ( Oncorhynchus mykiss ) was operated in Lake 375 and the impact of excess nutrients on the algal and bacteria communities was examined. The experiment was designed as a nutrient loading experiment with fish food and fish excretion the source of nutrients. Total N and P concentrations increased over the 4 years (15× and 4×, respectively). Phytoplankton biomass increased 4× annually following the start of aquaculture operation in 2003. The most dramatic responses occurred during spring and fall mixing, with blooms of chrysophytes and dinoflagellates increasing biomass by up to 12×. Bacteria biomass and densities were unaffected except for increases in late fall. Periphyton biomass was relatively unaffected except for an increase in biomass in the fourth year. The combination of a long water residence time in the lake coupled with an extremely high fish stocking density in Lake 375 resulted in an immediate impact on water quality. The results suggest that the impacts of aquaculture are accumulative and continual stocking will further impact water quality.

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