Hyperspectral remote sensing of submerged aquatic vegetation is a complex and difficult process that is affected by unique constraints on the energy flow profile near and below the water surface. In addition, shallow,...Hyperspectral remote sensing of submerged aquatic vegetation is a complex and difficult process that is affected by unique constraints on the energy flow profile near and below the water surface. In addition, shallow, winding, lotic systems, such as the Upper Delaware River, present additional remote sensing problems in the form of specular reflectance, variable depth and constituents in the water column and sometimes extremely weak signal strength due to absorption and scattering in the water column that can be statistically overwhelmed by the reflectance from upland vegetation in any individual image scene. Here we test hyperspectral imagery from the Civil Air Patrol’s (CAP), Airborne Real-time Cueing Hyperspectral Enhanced Recon (ARCHER) system in the scenic waters of two National Parks on the Upper Delaware River. A number of unique image processing problems were encountered, including specular reflectance from winding lotic systems, variable depth and flow dynamics of the riverine environment, and disproportionate signal strength from surface reflectance in this riverine environment. These problems were solved by applying a specular reflectance removal algorithm, applying field data collections to classification results and masking upland vegetation so as to not statistically overwhelm the weak reflectance signal from surface and near-surface water. Much was learned about conducting imaging spectroscopy in such difficult conditions. Important results include successful mapping of Submerged Aquatic Vegetation (SAV) presence/absence, advantages of upland masking of the reflectance signal, and a number of processing approaches that are unique to this environment. In this paper we summarize our results and identify unique issues that must be addressed in this environment.展开更多
Introduction:Submerged aquatic vegetation(SAV)has multiple functions in Lake Okeechobee.It provides critical habitat for fish and wildlife,stabilizes sediments,reduces phosphorus(P)concentration in the water column by...Introduction:Submerged aquatic vegetation(SAV)has multiple functions in Lake Okeechobee.It provides critical habitat for fish and wildlife,stabilizes sediments,reduces phosphorus(P)concentration in the water column by preventing re-suspension of P-rich sediments,and provides a substrate for attached algae,which also helps to remove P from the water column.Ten year water quality and SAV growth simulations are presented and compared with observed SAV and water quality data collected in the nearshore zone in Lake Okeechobee.Methods:The SAV theory and approach used in the LOEM are modified from the Chesapeake Bay model and incorporate three state variables:shoots(above the bed sediment),roots(in the bed sediment),and epiphytes(attached to the shoots).The SAV model has direct linkages with the water quality model,including(1)a link between the growth and decay of SAV and the nutrient pool of the water quality model;(2)a link between the photosynthesis and respiration of SAV and dissolved oxygen dynamics,and(3)the ways in which settling of particulate organic matter and nutrient uptake affect nutrient levels in the water column and in the sediment bed.Results:Total suspended solids affect light attenuation and are another major driving factor for SAV growth in the nearshore and littoral zone area.The model performs reasonably well in reproducing the spatial distribution of SAV.Conclusions:The theoretical analysis and model sensitivity tests indicate that SAV growth is primarily controlled by light and nutrients.The light available for SAV growth depends on the water depth and the turbidity.In this full scale simulation,the water depth comes from the LOEM hydrodynamic model,and the turbidity depends on the suspended sediment concentration and algal concentration.展开更多
Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers. One such vegetation component in North ...Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers. One such vegetation component in North American lakes and reservoirs is submerged aquatic vegetation—a valuable aquatic resource which serves as productive habitat for fish, aquatic macroinvertebrates, and other wildlife. Reservoirs in the southern parts of the United States have experienced varying aquatic plant dominance dynamics due to historical water resource management actions, including drawdowns and introduction of herbivorous fish for the purpose of controlling invasive aquatic vegetation. Some of these management options have also been detrimental to native submerged aquatic vegetation. This paper explores an adaptive management research effort by installing herbivore-protected, fenced-pen submerged aquatic vegetation sites in a high-herbivore reservoir to determine effectiveness of protecting habitat and serving as founder colony sources for propagule spread. Four experimental sites with three management treatments each were planted with American eelgrass. Each site utilized one un-fenced treatment and two treatments with varying mesh sizes for protective fencing-pens. Site integrity, species survival and spread, and grazing were documented. One additional site was installed and planted with other native submerged aquatic vegetation species for nominal species performance descriptions. No plants survived unprotected in the high-herbivore system and plants, in general, performed consistently better within the smaller mesh size. These test planting results were ultimately used to inform adaptive management decision making for plant installation and expansion designs for managing reservoirs invested with Hydrilla, considered one of the most serious invasive aquatic plants in the United States.展开更多
Introduction:The Chesapeake Bay was once renowned for expansive meadows of submerged aquatic vegetation(SAV).However,only 10%of the original meadows survive.Future restoration effortswill be complicated by acceleratin...Introduction:The Chesapeake Bay was once renowned for expansive meadows of submerged aquatic vegetation(SAV).However,only 10%of the original meadows survive.Future restoration effortswill be complicated by accelerating climate change,including physiological stressors such as a predicted mean temperature increase of 2-6℃and a 50-160%increase in CO_(2)concentrations.Outcomes:As the Chesapeake Bay begins to exhibit characteristics of a subtropical estuary,summer heat waves will become more frequent and severe.Warming alone would eventually eliminate eelgrass(Zostera marina)from the region.It will favor native heat-tolerant species such as widgeon grass(Ruppia maritima)while facilitating colonization by non-native seagrasses(e.g.,Halodule spp.).Intensifying human activity will also fuel coastal zone acidification and the resulting high CO_(2)/low pH conditions may benefit SAV via a“CO_(2)fertilization effect.”Discussion:Acidification is known to offset the effects of thermal stress and may have similar effects in estuaries,assuming water clarity is sufficient to support CO_(2)-stimulated photosynthesis and plants are not overgrown by epiphytes.However,coastal zone acidification is variable,driven mostly by local biological processes that may or may not always counterbalance the effects of regional warming.This precarious equipoise between two forces-thermal stress and acidification-will be critically important because it may ultimately determine the fate of cool-water plants such as Zostera marina in the Chesapeake Bay.Conclusion:The combined impacts of warming,coastal zone acidification,water clarity,and overgrowth of competing algae will determine the fate of SAV communities in rapidly changing temperate estuaries.展开更多
文摘Hyperspectral remote sensing of submerged aquatic vegetation is a complex and difficult process that is affected by unique constraints on the energy flow profile near and below the water surface. In addition, shallow, winding, lotic systems, such as the Upper Delaware River, present additional remote sensing problems in the form of specular reflectance, variable depth and constituents in the water column and sometimes extremely weak signal strength due to absorption and scattering in the water column that can be statistically overwhelmed by the reflectance from upland vegetation in any individual image scene. Here we test hyperspectral imagery from the Civil Air Patrol’s (CAP), Airborne Real-time Cueing Hyperspectral Enhanced Recon (ARCHER) system in the scenic waters of two National Parks on the Upper Delaware River. A number of unique image processing problems were encountered, including specular reflectance from winding lotic systems, variable depth and flow dynamics of the riverine environment, and disproportionate signal strength from surface reflectance in this riverine environment. These problems were solved by applying a specular reflectance removal algorithm, applying field data collections to classification results and masking upland vegetation so as to not statistically overwhelm the weak reflectance signal from surface and near-surface water. Much was learned about conducting imaging spectroscopy in such difficult conditions. Important results include successful mapping of Submerged Aquatic Vegetation (SAV) presence/absence, advantages of upland masking of the reflectance signal, and a number of processing approaches that are unique to this environment. In this paper we summarize our results and identify unique issues that must be addressed in this environment.
基金thank the Okeechobee Data Collection Team for SAV data collection.The authors also wish to thank Amy Peters for preparing Figures 2 and 3.
文摘Introduction:Submerged aquatic vegetation(SAV)has multiple functions in Lake Okeechobee.It provides critical habitat for fish and wildlife,stabilizes sediments,reduces phosphorus(P)concentration in the water column by preventing re-suspension of P-rich sediments,and provides a substrate for attached algae,which also helps to remove P from the water column.Ten year water quality and SAV growth simulations are presented and compared with observed SAV and water quality data collected in the nearshore zone in Lake Okeechobee.Methods:The SAV theory and approach used in the LOEM are modified from the Chesapeake Bay model and incorporate three state variables:shoots(above the bed sediment),roots(in the bed sediment),and epiphytes(attached to the shoots).The SAV model has direct linkages with the water quality model,including(1)a link between the growth and decay of SAV and the nutrient pool of the water quality model;(2)a link between the photosynthesis and respiration of SAV and dissolved oxygen dynamics,and(3)the ways in which settling of particulate organic matter and nutrient uptake affect nutrient levels in the water column and in the sediment bed.Results:Total suspended solids affect light attenuation and are another major driving factor for SAV growth in the nearshore and littoral zone area.The model performs reasonably well in reproducing the spatial distribution of SAV.Conclusions:The theoretical analysis and model sensitivity tests indicate that SAV growth is primarily controlled by light and nutrients.The light available for SAV growth depends on the water depth and the turbidity.In this full scale simulation,the water depth comes from the LOEM hydrodynamic model,and the turbidity depends on the suspended sediment concentration and algal concentration.
文摘Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers. One such vegetation component in North American lakes and reservoirs is submerged aquatic vegetation—a valuable aquatic resource which serves as productive habitat for fish, aquatic macroinvertebrates, and other wildlife. Reservoirs in the southern parts of the United States have experienced varying aquatic plant dominance dynamics due to historical water resource management actions, including drawdowns and introduction of herbivorous fish for the purpose of controlling invasive aquatic vegetation. Some of these management options have also been detrimental to native submerged aquatic vegetation. This paper explores an adaptive management research effort by installing herbivore-protected, fenced-pen submerged aquatic vegetation sites in a high-herbivore reservoir to determine effectiveness of protecting habitat and serving as founder colony sources for propagule spread. Four experimental sites with three management treatments each were planted with American eelgrass. Each site utilized one un-fenced treatment and two treatments with varying mesh sizes for protective fencing-pens. Site integrity, species survival and spread, and grazing were documented. One additional site was installed and planted with other native submerged aquatic vegetation species for nominal species performance descriptions. No plants survived unprotected in the high-herbivore system and plants, in general, performed consistently better within the smaller mesh size. These test planting results were ultimately used to inform adaptive management decision making for plant installation and expansion designs for managing reservoirs invested with Hydrilla, considered one of the most serious invasive aquatic plants in the United States.
基金This review was adapted from the author’s contributions to the Chesapeake Bay Submerged Aquatic Vegetation(SAV)Habitat Requirements and Restoration Targets:A Third Technical Synthesis funded by the U.S.Environmental Protection Agency through a Chesapeake Bay Implementation Grant authorized by section 117 of the Clean Water Act.The authors acknowledge the assistance of Brooke Laundry(MDDNR)and numerous members of the technical synthesis workgroup(2014-2017).
文摘Introduction:The Chesapeake Bay was once renowned for expansive meadows of submerged aquatic vegetation(SAV).However,only 10%of the original meadows survive.Future restoration effortswill be complicated by accelerating climate change,including physiological stressors such as a predicted mean temperature increase of 2-6℃and a 50-160%increase in CO_(2)concentrations.Outcomes:As the Chesapeake Bay begins to exhibit characteristics of a subtropical estuary,summer heat waves will become more frequent and severe.Warming alone would eventually eliminate eelgrass(Zostera marina)from the region.It will favor native heat-tolerant species such as widgeon grass(Ruppia maritima)while facilitating colonization by non-native seagrasses(e.g.,Halodule spp.).Intensifying human activity will also fuel coastal zone acidification and the resulting high CO_(2)/low pH conditions may benefit SAV via a“CO_(2)fertilization effect.”Discussion:Acidification is known to offset the effects of thermal stress and may have similar effects in estuaries,assuming water clarity is sufficient to support CO_(2)-stimulated photosynthesis and plants are not overgrown by epiphytes.However,coastal zone acidification is variable,driven mostly by local biological processes that may or may not always counterbalance the effects of regional warming.This precarious equipoise between two forces-thermal stress and acidification-will be critically important because it may ultimately determine the fate of cool-water plants such as Zostera marina in the Chesapeake Bay.Conclusion:The combined impacts of warming,coastal zone acidification,water clarity,and overgrowth of competing algae will determine the fate of SAV communities in rapidly changing temperate estuaries.
