“…; Johnson et al. ) and that the organic loading can produce a bell‐shaped response in the macroinvertebrate community (Norkko and Shumway ). Higher nutrients in water could provide a more adequate food source for the growth of macroinvertebrates than oligotrophic water (Chen et al.…”
Section: Discussionmentioning
confidence: 99%
“…The MEDIUM, HIGH, and FALLOW lakes were at a high level of nutrient loading, as indicated by higher Chl-a and total nitrogen. Past studies have shown that concentrations of nitrogen and phosphorus can affect the structure of aquatic communities (Pinnegar et al 2002;Schnitzler et al 2011;Johnson et al 2013) and that the organic loading can produce a bell-shaped response in the macroinvertebrate community (Norkko and Shumway 2011). Higher nutrients in water could provide a more adequate food source for the growth of macroinvertebrates than oligotrophic water Xie et al 2007), but macroinvertebrate diversity exhibited significant negative correlations with extremely high levels of nitrogen and phosphorus (Gong et al 2001;Huang et al 2013).…”
There is limited information available on the effects of extensive aquaculture or “fish ranching” operations on lake ecosystems. To study the effects of aquaculture on lake ecosystems, benthic macroinvertebrate communities were investigated from July to September 2015 in 23 lakes within the middle reach of the Yangtze River basin. The lakes represented four lake management strategies: fish ranching supported by low (LOW), medium (MEDIUM), or high (HIGH) stocking rates; or fallowing (FALLOW) in which previously ranched HIGH lakes had not been stocked for 2 years. Total macroinvertebrate densities did not vary significantly but were highest in the FALLOW lakes (2,352 individuals/m2), lowest in the LOW lakes (544 individuals/m2), and intermediate in the HIGH (1,734 individuals/m2) and MEDIUM lakes (1,208 individuals/m2). Chironomid densities were significantly lower in LOW lakes compared to all others, and mollusks were not observed in LOW lakes. Chironomid and total macroinvertebrate biomasses were also significantly lower in LOW lakes than in the other lakes. The FALLOW lakes had significantly greater biomasses of mollusks, oligochaetes, and total macroinvertebrates than all other lakes. Two pollution‐tolerant taxa, Tubificidae and Chironomidae, were dominant in all lakes regardless of management strategy, indicating that all study lakes were experiencing some degree of eutrophication. Results indicated that fish ranching does not affect macroinvertebrate communities in a predictable manner based on stocking density, but allowing for a fallowing period could potentially benefit lake macroinvertebrates. Canonical correspondence analysis indicated that chlorophyll a, chloride, conductivity, and total nitrogen were affecting macroinvertebrate density in these lakes, while total suspended solids, alkalinity, turbidity, total hardness, and water depth affected macroinvertebrate biomass.
“…; Johnson et al. ) and that the organic loading can produce a bell‐shaped response in the macroinvertebrate community (Norkko and Shumway ). Higher nutrients in water could provide a more adequate food source for the growth of macroinvertebrates than oligotrophic water (Chen et al.…”
Section: Discussionmentioning
confidence: 99%
“…The MEDIUM, HIGH, and FALLOW lakes were at a high level of nutrient loading, as indicated by higher Chl-a and total nitrogen. Past studies have shown that concentrations of nitrogen and phosphorus can affect the structure of aquatic communities (Pinnegar et al 2002;Schnitzler et al 2011;Johnson et al 2013) and that the organic loading can produce a bell-shaped response in the macroinvertebrate community (Norkko and Shumway 2011). Higher nutrients in water could provide a more adequate food source for the growth of macroinvertebrates than oligotrophic water Xie et al 2007), but macroinvertebrate diversity exhibited significant negative correlations with extremely high levels of nitrogen and phosphorus (Gong et al 2001;Huang et al 2013).…”
There is limited information available on the effects of extensive aquaculture or “fish ranching” operations on lake ecosystems. To study the effects of aquaculture on lake ecosystems, benthic macroinvertebrate communities were investigated from July to September 2015 in 23 lakes within the middle reach of the Yangtze River basin. The lakes represented four lake management strategies: fish ranching supported by low (LOW), medium (MEDIUM), or high (HIGH) stocking rates; or fallowing (FALLOW) in which previously ranched HIGH lakes had not been stocked for 2 years. Total macroinvertebrate densities did not vary significantly but were highest in the FALLOW lakes (2,352 individuals/m2), lowest in the LOW lakes (544 individuals/m2), and intermediate in the HIGH (1,734 individuals/m2) and MEDIUM lakes (1,208 individuals/m2). Chironomid densities were significantly lower in LOW lakes compared to all others, and mollusks were not observed in LOW lakes. Chironomid and total macroinvertebrate biomasses were also significantly lower in LOW lakes than in the other lakes. The FALLOW lakes had significantly greater biomasses of mollusks, oligochaetes, and total macroinvertebrates than all other lakes. Two pollution‐tolerant taxa, Tubificidae and Chironomidae, were dominant in all lakes regardless of management strategy, indicating that all study lakes were experiencing some degree of eutrophication. Results indicated that fish ranching does not affect macroinvertebrate communities in a predictable manner based on stocking density, but allowing for a fallowing period could potentially benefit lake macroinvertebrates. Canonical correspondence analysis indicated that chlorophyll a, chloride, conductivity, and total nitrogen were affecting macroinvertebrate density in these lakes, while total suspended solids, alkalinity, turbidity, total hardness, and water depth affected macroinvertebrate biomass.
“…Macrofaunal induced flushing of sediments with oxygen enriched bottom waters can be expected to enhance oxygen fluxes in summer and autumn, when the oxygen penetration into the sediment decreases (Lohse et al, 1995). Especially suspension feeder such as Ensis directus should have a pronounced effect on benthic oxygen fluxes irrigating the sediment (Norkko and Shumway, 2011). For the German Bight, Forster et al (1999) estimated that bioirrigation dominantly drives benthic oxygen consumption, while a relatively small portion of oxygen is used for respiration of benthic macrofauna.…”
Section: Seasonal Variations Of Oxygen and Nitrogen Fluxesmentioning
“…These impacts on benthic communities due to increased organic matter can include changes in the size and structure of benthic community composition (Ferreira et al . ; Norkko & Shumway ). Benthic effects are normally restricted to swathes of seabed directly below growing lines and less than 30 m wide (Lloyd ).…”
Section: Environmental Impacts Of Mussel Farmingmentioning
confidence: 99%
“…). One way to avoid these impacts is through the adoption of Best Management Practices (BMP) such as selection of farming sites with appropriate depth and water flow characteristics and adoption of farm layouts that avoid excessive densities (Hargreaves ; Norkko & Shumway ). The use of bottom video/imaging surveillance and the monitoring of potential Redox and total free sulphide (S) levels in the surface sediment under mussel farms and undisturbed areas are control measures that allow the early detection of problems with sediment deterioration (Hargrave et al .…”
Section: Environmental Impacts Of Mussel Farmingmentioning
This review analyses how mussel farming can contribute to the challenge of feeding the current and future world population in a more efficient and sustainable way. The analysis lays a foundation of the main issues with current practices of animal protein production, and compares them with the alternative of a massive expansion of mussel farming as a means to produce high‐quality protein for human and animal nutrition. The review also covers the ecological goods and services that mussels provide to the ocean and to the atmosphere, the health of mussel products, and the many potential uses of by‐products from the mussel industry in agriculture, in wastewater treatment, and in the feed industry.
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