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Moshe Kiflawi - One of the best experts on this subject based on the ideXlab platform.
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Grazing Pressure on coral reefs decreases across a wide depth gradient in the gulf of aqaba red sea
Marine Ecology Progress Series, 2010Co-Authors: Eran Brokovich, Inbal Ayalon, Shai Einbinder, Nitzan Segev, Yonathan Shaked, Amatzia Genin, Salit Kark, Moshe KiflawiAbstract:Algae are an essential component of healthy coral reefs and serve as the base of the food chain and as a living habitat for numerous organisms. Herbivorous fish play an important role in coral reef ecology by mediating competition between fast-growing algae and relatively slow-growing corals. However, because of diving-related difficulties, the importance of herbivory in deep mesophotic coral reefs (30 to 150 m) remains largely unknown. We examined the relationship between herbivores and algae along a depth gradient down to 65 m, and evaluated Grazing Pressure along the depth gradient. We visually assessed the abundance of herbivorous fish along the depth gradient and estimated fish biomass. We measured in situ turf algae growth rates and performed experimental assessments of Grazing Pressure using settlement plates and bioassays. We discovered that, while both algal growth and fish density decrease with depth, the decrease in Grazing Pressure is steeper, with a consumption of <20% of turf-algae production at 65 m versus 40 to 60% at depths of 5 to 20 m. Concomitantly, a decrease in fish biomass and density along the depth gradient reduced potential Grazing Pressure on macroalgae. Our findings suggest a less important role for herbivorous fish in maintaining algal-free substrate for coral recruitment and growth in deep zones compared with the shallow reef.
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Grazing Pressure on coral reefs decreases across a wide depth gradient in the Gulf of Aqaba, Red Sea
Marine Ecology Progress Series, 2010Co-Authors: Eran Brokovich, Inbal Ayalon, Shai Einbinder, Nitzan Segev, Yonathan Shaked, Amatzia Genin, Salit Kark, Moshe KiflawiAbstract:Algae are an essential component of healthy coral reefs and serve as the base of the food chain and as a living habitat for numerous organisms. Herbivorous fish play an important role in coral reef ecology by mediating competition between fast-growing algae and relatively slow-growing corals. However, because of diving-related difficulties, the importance of herbivory in deep mesophotic coral reefs (30 to 150 m) remains largely unknown. We examined the relationship between herbivores and algae along a depth gradient down to 65 m, and evaluated Grazing Pressure along the depth gradient. We visually assessed the abundance of herbivorous fish along the depth gradient and estimated fish biomass. We measured in situ turf algae growth rates and performed experimental assessments of Grazing Pressure using settlement plates and bioassays. We discovered that, while both algal growth and fish density decrease with depth, the decrease in Grazing Pressure is steeper, with a consumption of
James T. Green - One of the best experts on this subject based on the ideXlab platform.
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runoff water quality from manured riparian grasslands with contrasting drainage and simulated Grazing Pressure
Agriculture Ecosystems & Environment, 2008Co-Authors: David M. Butler, Noah N. Ranells, Dorcas H. Franklin, Matthew H Poore, James T. GreenAbstract:Globally,management ofgrazedriparian areasiscriticallyimportanttoagriculturalsustainabilityandenvironmentalquality.However,the potential impacts of riparian Grazing management on water quality are not well-documented, particularly in the southeastern USA. The objective of this work was to determine sediment and nutrient export under simulated rainfall from poorly drained and well-drained riparian soils where heavy or light Grazing Pressure by cattle was simulated. Plots were established on stands of existing vegetation to create Grazing Pressure treatments of (a) light-use (full ground cover, uncompacted), and with stands modified to establish (b) heavy-use (bare ground, compacted) treatments. Vegetation on poorly drained soils consisted of several typical wetland species (e.g., Pontederia cordata L., Juncus coriaceus Mackenzie) in the southeastern USA, whereas mixed tall fescue (Festuca arundinacea Schreb.)‐dallisgrass (Paspalum dilatatum Poir.) stands were the dominant vegetation on well-drained soils. Runoff volumewas generally greater from heavy-use than from light-use for poorly drained soils and for well-drained soils. Greater runoff volume was also observed from poorly drained soils compared to well-drained soils for both light-use and for heavy-use treatments. Light-use plots were remarkably effective at minimizing export of total suspended solids (TSS)onboth soils (<30 kg ha � 1 ). Mean total Kjeldahl P(TKP) exportwas fourfold greater from heavy-useplots than from light-use plots on both soils. While export of nitrate-nitrogen (NO3-N) was unaffected by Grazing Pressure and soil drainage, mean ammonium-nitrogen (NH4N) and total N (TN) export from poorly drained heavy-use plots was greater than fivefold that from well-drained light-use plots. Results indicate that livestock heavy-use areas in the riparian zone may export substantial TSS and nutrients, especially on poorly drained soils. However, when full ground cover is maintained on well-drained soils, TSS and nutrient losses may be limited. # 2008 Elsevier B.V. All rights reserved.
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Runoff water quality from manured riparian grasslands with contrasting drainage and simulated Grazing Pressure
Agriculture Ecosystems & Environment, 2008Co-Authors: David M. Butler, Noah N. Ranells, Dorcas H. Franklin, Matthew H Poore, James T. GreenAbstract:Globally,management ofgrazedriparian areasiscriticallyimportanttoagriculturalsustainabilityandenvironmentalquality.However,the potential impacts of riparian Grazing management on water quality are not well-documented, particularly in the southeastern USA. The objective of this work was to determine sediment and nutrient export under simulated rainfall from poorly drained and well-drained riparian soils where heavy or light Grazing Pressure by cattle was simulated. Plots were established on stands of existing vegetation to create Grazing Pressure treatments of (a) light-use (full ground cover, uncompacted), and with stands modified to establish (b) heavy-use (bare ground, compacted) treatments. Vegetation on poorly drained soils consisted of several typical wetland species (e.g., Pontederia cordata L., Juncus coriaceus Mackenzie) in the southeastern USA, whereas mixed tall fescue (Festuca arundinacea Schreb.)‐dallisgrass (Paspalum dilatatum Poir.) stands were the dominant vegetation on well-drained soils. Runoff volumewas generally greater from heavy-use than from light-use for poorly drained soils and for well-drained soils. Greater runoff volume was also observed from poorly drained soils compared to well-drained soils for both light-use and for heavy-use treatments. Light-use plots were remarkably effective at minimizing export of total suspended solids (TSS)onboth soils (
Haijun Wang - One of the best experts on this subject based on the ideXlab platform.
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Crustacean zooplankton size structure in aquaculture lakes : is larger size structure always associated with higher Grazing Pressure?
Hydrobiologia, 2006Co-Authors: Songbo Wang, Ping Xie, Haijun WangAbstract:Crustacean zooplankton size structure in 27 aquaculture lakes was studied to test the hypothesis that larger size structure is associated with higher Grazing Pressure. Mean body length of crustaceans was positively correlated with increasing Chl a (r(2) = 0.40, P = 0.000) and TP (r(2) = 0.38, P = 0.000), contrary to the empirical studies. However, the ratio of zooplankton to phytoplankton biomass decreased significantly with increasing TP (r(2) = 0.27, P = 0.005) and mean body length (r(2) = 0.46, P = 0.000). Meanwhile, size structure showed no significant effect in explaining residual variations of phosphorus-chlorophyll relationship (P = 0.231). These results indicate that larger size structure was not always associated with higher zooplankton Grazing Pressure. It is likely that in aquaculture lakes crustacean zooplankton size structure was of minor importance in control of phytoplankton biomass, and it was mainly regulated by fish predation. The results showed in our study and the empirical studies might be a reflection of two different stages of lake eutrophication and fish predation intensity.
Eran Brokovich - One of the best experts on this subject based on the ideXlab platform.
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Grazing Pressure on coral reefs decreases across a wide depth gradient in the gulf of aqaba red sea
Marine Ecology Progress Series, 2010Co-Authors: Eran Brokovich, Inbal Ayalon, Shai Einbinder, Nitzan Segev, Yonathan Shaked, Amatzia Genin, Salit Kark, Moshe KiflawiAbstract:Algae are an essential component of healthy coral reefs and serve as the base of the food chain and as a living habitat for numerous organisms. Herbivorous fish play an important role in coral reef ecology by mediating competition between fast-growing algae and relatively slow-growing corals. However, because of diving-related difficulties, the importance of herbivory in deep mesophotic coral reefs (30 to 150 m) remains largely unknown. We examined the relationship between herbivores and algae along a depth gradient down to 65 m, and evaluated Grazing Pressure along the depth gradient. We visually assessed the abundance of herbivorous fish along the depth gradient and estimated fish biomass. We measured in situ turf algae growth rates and performed experimental assessments of Grazing Pressure using settlement plates and bioassays. We discovered that, while both algal growth and fish density decrease with depth, the decrease in Grazing Pressure is steeper, with a consumption of <20% of turf-algae production at 65 m versus 40 to 60% at depths of 5 to 20 m. Concomitantly, a decrease in fish biomass and density along the depth gradient reduced potential Grazing Pressure on macroalgae. Our findings suggest a less important role for herbivorous fish in maintaining algal-free substrate for coral recruitment and growth in deep zones compared with the shallow reef.
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Grazing Pressure on coral reefs decreases across a wide depth gradient in the Gulf of Aqaba, Red Sea
Marine Ecology Progress Series, 2010Co-Authors: Eran Brokovich, Inbal Ayalon, Shai Einbinder, Nitzan Segev, Yonathan Shaked, Amatzia Genin, Salit Kark, Moshe KiflawiAbstract:Algae are an essential component of healthy coral reefs and serve as the base of the food chain and as a living habitat for numerous organisms. Herbivorous fish play an important role in coral reef ecology by mediating competition between fast-growing algae and relatively slow-growing corals. However, because of diving-related difficulties, the importance of herbivory in deep mesophotic coral reefs (30 to 150 m) remains largely unknown. We examined the relationship between herbivores and algae along a depth gradient down to 65 m, and evaluated Grazing Pressure along the depth gradient. We visually assessed the abundance of herbivorous fish along the depth gradient and estimated fish biomass. We measured in situ turf algae growth rates and performed experimental assessments of Grazing Pressure using settlement plates and bioassays. We discovered that, while both algal growth and fish density decrease with depth, the decrease in Grazing Pressure is steeper, with a consumption of
David M. Butler - One of the best experts on this subject based on the ideXlab platform.
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runoff water quality from manured riparian grasslands with contrasting drainage and simulated Grazing Pressure
Agriculture Ecosystems & Environment, 2008Co-Authors: David M. Butler, Noah N. Ranells, Dorcas H. Franklin, Matthew H Poore, James T. GreenAbstract:Globally,management ofgrazedriparian areasiscriticallyimportanttoagriculturalsustainabilityandenvironmentalquality.However,the potential impacts of riparian Grazing management on water quality are not well-documented, particularly in the southeastern USA. The objective of this work was to determine sediment and nutrient export under simulated rainfall from poorly drained and well-drained riparian soils where heavy or light Grazing Pressure by cattle was simulated. Plots were established on stands of existing vegetation to create Grazing Pressure treatments of (a) light-use (full ground cover, uncompacted), and with stands modified to establish (b) heavy-use (bare ground, compacted) treatments. Vegetation on poorly drained soils consisted of several typical wetland species (e.g., Pontederia cordata L., Juncus coriaceus Mackenzie) in the southeastern USA, whereas mixed tall fescue (Festuca arundinacea Schreb.)‐dallisgrass (Paspalum dilatatum Poir.) stands were the dominant vegetation on well-drained soils. Runoff volumewas generally greater from heavy-use than from light-use for poorly drained soils and for well-drained soils. Greater runoff volume was also observed from poorly drained soils compared to well-drained soils for both light-use and for heavy-use treatments. Light-use plots were remarkably effective at minimizing export of total suspended solids (TSS)onboth soils (<30 kg ha � 1 ). Mean total Kjeldahl P(TKP) exportwas fourfold greater from heavy-useplots than from light-use plots on both soils. While export of nitrate-nitrogen (NO3-N) was unaffected by Grazing Pressure and soil drainage, mean ammonium-nitrogen (NH4N) and total N (TN) export from poorly drained heavy-use plots was greater than fivefold that from well-drained light-use plots. Results indicate that livestock heavy-use areas in the riparian zone may export substantial TSS and nutrients, especially on poorly drained soils. However, when full ground cover is maintained on well-drained soils, TSS and nutrient losses may be limited. # 2008 Elsevier B.V. All rights reserved.
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Runoff water quality from manured riparian grasslands with contrasting drainage and simulated Grazing Pressure
Agriculture Ecosystems & Environment, 2008Co-Authors: David M. Butler, Noah N. Ranells, Dorcas H. Franklin, Matthew H Poore, James T. GreenAbstract:Globally,management ofgrazedriparian areasiscriticallyimportanttoagriculturalsustainabilityandenvironmentalquality.However,the potential impacts of riparian Grazing management on water quality are not well-documented, particularly in the southeastern USA. The objective of this work was to determine sediment and nutrient export under simulated rainfall from poorly drained and well-drained riparian soils where heavy or light Grazing Pressure by cattle was simulated. Plots were established on stands of existing vegetation to create Grazing Pressure treatments of (a) light-use (full ground cover, uncompacted), and with stands modified to establish (b) heavy-use (bare ground, compacted) treatments. Vegetation on poorly drained soils consisted of several typical wetland species (e.g., Pontederia cordata L., Juncus coriaceus Mackenzie) in the southeastern USA, whereas mixed tall fescue (Festuca arundinacea Schreb.)‐dallisgrass (Paspalum dilatatum Poir.) stands were the dominant vegetation on well-drained soils. Runoff volumewas generally greater from heavy-use than from light-use for poorly drained soils and for well-drained soils. Greater runoff volume was also observed from poorly drained soils compared to well-drained soils for both light-use and for heavy-use treatments. Light-use plots were remarkably effective at minimizing export of total suspended solids (TSS)onboth soils (
