scholarly journals Large-Scale Mapping and Predictive Modeling of Submerged Aquatic Vegetation in a Shallow Eutrophic Lake

2002 ◽  
Vol 2 ◽  
pp. 949-965 ◽  
Author(s):  
Karl E. Havens ◽  
Matthew C. Harwell ◽  
Mark A. Brady ◽  
Bruce Sharfstein ◽  
Therese L. East ◽  
...  
Keyword(s):  
Large Scale ◽  
Submerged Aquatic Vegetation ◽  
Aquatic Vegetation ◽  
Eutrophic Lake ◽  
Sediment Type ◽  
Gis Technology ◽  
General Utility ◽  
Sediment Types ◽  
Wide Range ◽  
Sampling Program

A spatially intensive sampling program was developed for mapping the submerged aquatic vegetation (SAV) over an area of approximately 20,000 ha in a large, shallow lake in Florida, U.S. The sampling program integrates Geographic Information System (GIS) technology with traditional field sampling of SAV and has the capability of producing robust vegetation maps under a wide range of conditions, including high turbidity, variable depth (0 to 2 m), and variable sediment types. Based on sampling carried out in AugustœSeptember 2000, we measured 1,050 to 4,300 ha of vascular SAV species and approximately 14,000 ha of the macroalga Chara spp. The results were similar to those reported in the early 1990s, when the last large-scale SAV sampling occurred. Occurrence of Chara was strongly associated with peat sediments, and maximal depths of occurrence varied between sediment types (mud, sand, rock, and peat). A simple model of Chara occurrence, based only on water depth, had an accuracy of 55%. It predicted occurrence of Chara over large areas where the plant actually was not found. A model based on sediment type and depth had an accuracy of 75% and produced a spatial map very similar to that based on observations. While this approach needs to be validated with independent data in order to test its general utility, we believe it may have application elsewhere. The simple modeling approach could serve as a coarse-scale tool for evaluating effects of water level management on Chara populations.

Spatial and temporal distribution of submerged aquatic vegetation in a tropical coastal lagoon habitat in Viet Nam

2018 ◽  
Vol 61 (3) ◽  
pp. 213-224 ◽  
Author(s):  
T.T. Hang Phan ◽  
Iris Stiers ◽  
T.T. Huong Nguyen ◽  
T. Tuyet Pham ◽  
T. Phap Ton ◽  
...  
Keyword(s):  
Coastal Lagoon ◽  
Submerged Aquatic Vegetation ◽  
Aquatic Vegetation ◽  
Coastal Lagoons ◽  
Predictor Variable ◽  
Viet Nam ◽  
Total Biomass ◽  
Sediment Types ◽  
Najas Indica ◽  
Wide Range

Abstract Submerged aquatic vegetation (SAV) is considered as a keystone habitat, contributing significantly to structure and function of coastal lagoons. However, limited understanding of the factors driving SAV distribution and abundance across a wide range of salinity in tropical coastal lagoons has restricted the effectiveness of managing and preserving the ecosystem services in coastal lagoon habitats. This study examined the distribution and abundance of SAV species in the growing season in relation to water physico-chemical variables and grain sizes of sediment types in a tropical lagoon in Viet Nam. The results revealed that Najas indica and Halophila beccarii were the dominant species in the community of 7 SAV species, accounting for 70% of the total cover and 55% of the total biomass sampled. Variation partitioning showed that both water and sediment variables were important in explaining spatial distribution and abundance of SAV species across the coastal lagoon. Salinity was the most significant predictor variable that accounted for the variation of SAV species data. The study implied that changes of salinity and silt (versus sand) particles can lead to different SAV assemblages in the lagoon.

scholarly journals Remote sensing of submerged aquatic vegetation: an introduction and best practices review

2020 ◽  
Author(s):  
Gillian Rowan ◽  
Margaret Kalacska
Keyword(s):  
Remote Sensing ◽  
Best Practices ◽  
Large Scale ◽  
Submerged Aquatic Vegetation ◽  
Aquatic Vegetation ◽  
Global Climate ◽  
Underwater Environment ◽  
Sensor Platform ◽  
Wide Range ◽  
Optical Imagery

Submerged aquatic vegetation (SAV) is a critical component of aquatic ecosystems. It is however understudied and rapidly changing due to global climate change and anthropogenic disturbances. Remote sensing can provide the efficient, accurate and large-scale monitoring needed to ensure proper SAV management. Our objective is to introduce remote sensing to researchers in the field of aquatic ecology. Applying remote sensing to the underwater environment is more complex in comparison to terrestrial studies due to the water column. A wide range of sensors and platforms from remotely operated vehicles to satellites are available for use in the underwater environment, a sample of which being presented herein. The utility of any sensor/platform combination varies depending on the aquatic conditions being observed. An overview of the required corrections, processing, and analysis methods for passive optical imagery is presented and discussed. Previous applications of remote sensing to identify and detecting SAV are briefly presented and notable results and lessons are discussed.

scholarly journals Novel approach for large‐scale monitoring of submerged aquatic vegetation – a nationwide example from Sweden

2021 ◽  
Author(s):  
Silvia Huber ◽  
Lars B. Hansen ◽  
Lisbeth T. Nielsen ◽  
Mikkel L. Rasmussen ◽  
Jonas Sølvsteen ◽  
...  
Keyword(s):  
Large Scale ◽  
Submerged Aquatic Vegetation ◽  
Aquatic Vegetation ◽  
Novel Approach

Estimating acoustic attenuation from a quantitative seismic profiler

Geophysics ◽  
1981 ◽  
Vol 46 (10) ◽  
pp. 1364-1378 ◽  
Author(s):  
Robert C. Tyce
Keyword(s):  
Sediment Type ◽  
Carbonate Sediments ◽  
Seismic Profiles ◽  
Acoustic Attenuation ◽  
Sea Floor ◽  
Sediment Types ◽  
Physical Laboratory ◽  
High Lateral Resolution ◽  
Wide Range ◽  
Depth Of Burial

Recent work has indicated that acoustic attenuation in marine sediments can be estimated from thin wedges of sediment by means of a quantitative seismic profiler. A capability for near‐bottom seismic profiling at 4 kHz has been developed at the Scripps Institution of Oceanography Marine Physical Laboratory and utilized to determine effective attenuation for several areas of the sea floor. As part of the deep‐tow instrumentation system of the Marine Physical Laboratory, this profiler provides very high lateral resolution. Real time computer displays of equivalent plane‐wave pressure and intensity for seismic profiles have been developed as part of this system. These displays are produced on a standard graphic recorder and can be employed directly to determine effective attenuation by plotting displayed equivalent intensity as a function of depth of burial for a reflector covered by a wedge of sediment. For pelagic sediments, values of about 0.25 dB/m at 4 kHz appear to be common. For the Southern California borderland, a wide range of sediment types is observed, with measured values of effective attenuation ranging from 0.21 to 0.63 dB/m. Highly calcareous (85 percent carbonate) sediments of the Carnegie ridge give quite low values, from 0.1 to 0.2 dB/m, with a suggestion of a rapid decrease in attenuation with depth. For nonbiogenous sediments, values of effective attenuation appear useful for predicting other physical properties such as grain size and porosity, as well as general sediment type, from established interrelations.

scholarly journals A Review of Remote Sensing of Submerged Aquatic Vegetation for Non-Specialists

2021 ◽  
Vol 13 (4) ◽  
pp. 623
Author(s):  
Gillian S. L. Rowan ◽  
Margaret Kalacska
Keyword(s):  
Remote Sensing ◽  
Water Column ◽  
Large Scale ◽  
Submerged Aquatic Vegetation ◽  
Aquatic Vegetation ◽  
Global Climate ◽  
Training Data ◽  
Suspended Particulate ◽  
The Subject

Submerged aquatic vegetation (SAV) is a critical component of aquatic ecosystems. It is however understudied and rapidly changing due to global climate change and anthropogenic disturbances. Remote sensing (RS) can provide the efficient, accurate and large-scale monitoring needed for proper SAV management and has been shown to produce accurate results when properly implemented. Our objective is to introduce RS to researchers in the field of aquatic ecology. Applying RS to underwater ecosystems is complicated by the water column as water, and dissolved or suspended particulate matter, interacts with the same energy that is reflected or emitted by the target. This is addressed using theoretical or empiric models to remove the water column effect, though no model is appropriate for all aquatic conditions. The suitability of various sensors and platforms to aquatic research is discussed in relation to both SAV as the subject and to project aims and resources. An overview of the required corrections, processing and analysis methods for passive optical imagery is presented and discussed. Previous applications of remote sensing to identify and detect SAV are briefly presented and notable results and lessons are discussed. The success of previous work generally depended on the variability in, and suitability of, the available training data, the data’s spatial and spectral resolutions, the quality of the water column corrections and the level to which the SAV was being investigated (i.e., community versus species.)

scholarly journals Seagrass and Submerged Aquatic Vegetation (VAS) Habitats off the Coast of Brazil: state of knowledge, conservation and main threats

2016 ◽  
Vol 64 (spe2) ◽  
pp. 53-80 ◽  
Author(s):  
Margareth S. Copertino ◽  
Joel C. Creed ◽  
Marianna O. Lanari ◽  
Karine Magalhães ◽  
Kcrishna Barros ◽  
...  
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Submerged Aquatic Vegetation ◽  
Aquatic Vegetation ◽  
Conservation Status ◽  
Current Status ◽  
Brazilian Coast ◽  
Global Changes ◽  
Seagrass Meadows ◽  
Ecological Features

Abstract Seagrass meadows are among the most threatened ecosystems on earth, raising concerns about the equilibrium of coastal ecosystems and the sustainability of local fisheries. The present review evaluated the current status of the research on seagrasses and submerged aquatic vegetation (SAV) habitats off the coast of Brazil in terms of plant responses to environmental conditions, changes in distribution and abundance, and the possible role of climate change and variability. Despite an increase in the number of studies, the communication of the results is still relatively limited and is mainly addressed to a national or regional public; thus, South American seagrasses are rarely included or cited in global reviews and models. The scarcity of large-scale and long-term studies allowing the detection of changes in the structure, abundance and composition of seagrass habitats and associated species still hinders the investigation of such communities with respect to the potential effects of climate change. Seagrass meadows and SAV occur all along the Brazilian coast, with species distribution and abundance being strongly influenced by regional oceanography, coastal water masses, river runoff and coastal geomorphology. Based on these geomorphological, hydrological and ecological features, we characterised the distribution of seagrass habitats and abundances within the major coastal compartments. The current conservation status of Brazilian seagrasses and SAV is critical. The unsustainable exploitation and occupation of coastal areas and the multifold anthropogenic footprints left during the last 100 years led to the loss and degradation of shoreline habitats potentially suitable for seagrass occupation. Knowledge of the prevailing patterns and processes governing seagrass structure and functioning along the Brazilian coast is necessary for the global discussion on climate change. Our review is a first and much-needed step toward a more integrated and inclusive approach to understanding the diversity of coastal plant formations along the Southwestern Atlantic coast as well as a regional alert the projected or predicted effects of global changes on the goods and services provided by regional seagrasses and SAV.

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