Modeling acoustic volume backscatter from two shallow-water marine environments by side-scan sonar

Basead on extensive collections of cnidarians from Brazilian shallow-water marine environments, new occurrences of four species of associated barnacles are cited, the first three being redescribed; Tne archaeobalanid Conopea galeata, asssociated with the gorgonians Muriceopsis sulphurea, Lophogorgia punicea and Heterogorgia sp from the States of Paraíba, Bahia, Rio de Janeiro and São Paulo; the balanid Megabalanus stultus, associated with the hydrozoans Millepora spp from Paraíba to Alagoas and from the south of Bahia to Rio de Janeiro; the pyrgomatids Megatrema madreporarum, associated with the scleractinian corals Agaricia spp from Paraíba to Alagoas and the south of Bahia, and Ceratoconcha floridanum, associated with the seleractinian coral Mussismilia hispida from Atol das Rodas and Rio de Janeiro.

Download Full-text

Processing Data for Seafloor Mapping: Integration and Metrics

Marine Technology Society Journal ◽

10.4031/002533201788058017 ◽

2001 ◽

Vol 35 (4) ◽

pp. 20-32 ◽

Cited By ~ 4

Author(s):

Shannon Byrne ◽

Brian Clifford ◽

Walter Simmons ◽

Jan Depner ◽

Barbara Reed ◽

...

Keyword(s):

Shallow Water ◽

Data Cleaning ◽

Data Set ◽

Side Scan Sonar ◽

Cleaning Validation ◽

Sonar System ◽

Sonar Systems ◽

Application Data ◽

Definition Of ◽

The University

Today's state-of-the-art hydrographic survey instrumentation produces higher resolution and more densely sampled measurements than were available in the past. This supports improvements in the definition of seafloor features and characteristics, however, it also places more stringent requirements on the systems used to process seafloor survey data. In shallow water environments bathymetric sampling rates can exceed 4000 soundings per second and data from Digital Side-Scan Sonar Systems can exceed 1 Gb/hr. In support of the Second International Conference on High-Resolution Surveys in Shallow Water, and working in cooperation with Reson Inc., Goleta, Ca., and the University of New Hampshire's Center for Coastal and Ocean Mapping (CCOM), Science Applications International Corporation (SAIC), Newport, RI conducted a survey of the conference common data set test area in Portsmouth Harbor using a Reson 8125 dual-head sonar system. The acquired data were made available as part of the conference common dataset. An area-based approach to data cleaning, including the use of an automated filter for spike detection, is presented. Resource and effort metrics associated with the processing of samples from the common data set are provided. This includes corrector application, data cleaning, validation, and quality control. Results from the area-based approach are compared with results from a traditional line-oriented approach. Three bathymetric datasets from Portsmouth Harbor are compared and the results reported.

Download Full-text

Shallow water High Resolution Bathymetric Side Scan Sonar

OCEANS 2007 - Europe ◽

10.1109/oceanse.2007.4302272 ◽

2007 ◽

Cited By ~ 1

Author(s):

Xiaodong Liu ◽

Weiqing Zhu ◽

Changle Fang ◽

Wen Xu ◽

Fangsheng Zhang ◽

...

Keyword(s):

High Resolution ◽

Shallow Water ◽

Side Scan Sonar

Download Full-text

The unusual biology of marine file snakes with a perspective for the conservation of Acrochordus granulatus

10.26757/pjsb2020b14010 ◽

2021 ◽

Vol 14 (2) ◽

Keyword(s):

Climate Change ◽

Shallow Water ◽

The Philippines ◽

Habitat Destruction ◽

Oxygen Storage ◽

Anthropogenic Factors ◽

Marine Environments ◽

Coastal Environments ◽

Coastal Habitats ◽

Distinct Evolutionary Lineage

Biodiversity and the function of tropical shallow-water marine environments are threatened by numerous anthropogenic factors, especially climate change, overharvesting of resources, and destruction of habitat. Marine snakes are important components of coastal shallow-water systems and should be considered as indicators of the health of coastal ecosystems such as mangroves. Acrochordid snakes (Acrochordidae: Acrochordus) represent a highly distinct evolutionary lineage with unusual adaptations to shallow water habitats and importance to biodiversity of tropical coastal regions. One of three congeneric species, Acrochordus granulatus (file snake), is an interesting and common inhabitant of coastal estuaries and mangroves in the Philippines. This paper reviews unusual attributes of A. granulatus and provides a perspective for its conservation in coastal habitats. Morphological, physiological, and behavioral characters of this snake are specialized for life in shallow-water marine environments such as mangroves. Unusual and specialized features confer abilities for prolonged submergence and include low metabolic rate, large capacity for oxygen storage, cutaneous gas exchange, nearly complete utilization of oxygen stores during aerobic submergence, intracardiac and cutaneous shunts for regulating blood flow, and reclusive behavior. Fresh water is required for water balance, and file snakes are dependent on rainfall in many habitats where they drink from freshwater lenses formed by precipitation on the surfaces of marine water. File snakes feed largely on fishes and are candidates as bio-indicators of the health of shallow-water coastal habitats. Attention should be given to threatening insults on coastal environments including climate change, habitat destruction, harvesting of resources, and other factors in need of research, monitoring, and plans for abatement. Importantly, conservation can be promoted by educating people about the docile behavior, unusual traits, and interesting ecology of A. granulatus. KEYWORDS: mangrove, shallow water, Acrochordidae, little file snake, conservation physiology, ecophysiology

Download Full-text

Host-symbiont stress response to lack-of-sulfide in the giant ciliate mutualism

10.1101/2021.07.27.454000 ◽

2021 ◽

Author(s):

Salvador Espada-Hinojosa ◽

Judith Drexel ◽

Julia Kesting ◽

Edwin Kniha ◽

Iason Pifeas ◽

...

Keyword(s):

Stress Response ◽

Shallow Water ◽

Carbon Fixation ◽

Marine Environments ◽

Symbiont Transmission ◽

Sulfur Oxidizing ◽

Over Time

The thiotrophic mutualism between the sulfur-oxidizing, chemoautotrophic (thiotrophic) bacterial ectosymbiont Candidatus Thiobius zoothamnicola and the giant ciliate Zoothamnium niveum thrives in a variety of shallow-water marine environments with highly fluctuating sulfide emission. To persist over time both partners must reproduce and ensure symbiont transmission prior cessation of sulfide, fueling the symbiont’s carbon fixation and host nourishment. We experimentally investigated the response of this mutualism to waning of sulfide. We found that colonies followed the r-strategy and released initially present but also newly produced macrozooids until death. A fraction of middle-sized longer-lived colonies were particularly proficient in producing and releasing swarmers. The symbionts on the colonies proliferated less and became larger and more rod-shaped under oxic conditions compared to symbionts from freshly collected colonies exposed to sulfide and oxygen. The symbiont monolayer was highly disturbed with epigrowth of other microbes and loss of symbionts that were subsequently found in the experimental seawater. We conclude that both partners’ response to cessation of sulfide emission was remarkably fast. The colony experienced death within two days but host reproduction through swarmers carrying the symbiont ensured the continuation of the association.

Download Full-text

Classification of stones in coastal marine environments using random forest machine learning on topo-bathymetric LiDAR data

10.5194/egusphere-egu21-8254 ◽

2021 ◽

Author(s):

Signe Schilling Hansen ◽

Verner Brandbyge Ernstsen ◽

Mikkel Skovgaard Andersen ◽

Zyad Al-Hamdani ◽

Ramona Baran ◽

...

Keyword(s):

Machine Learning ◽

Ecosystem Services ◽

Random Forest ◽

Shallow Water ◽

Airborne Lidar ◽

Habitat Mapping ◽

Lidar Data ◽

Marine Environments ◽

Automated Method ◽

Coastal Marine

Stones on the seabed in coastal marine environments form an important hard substrate for macroalgae, and hence for coastal marine reefs. Such reef areas constitute important ecosystem services, e.g. storage of organic carbon in macroalgae or &#8220;blue carbon&#8221; as well as important habitats to fish for living, hiding and feeding. Information and knowledge about stone locations and geometry in coastal marine environments are often obtained as part of seabed habitat mapping. Usually, seabed habitat mapping is based on geophysical surveys using multibeam echo sounding along with side-scan sonar imaging in combination with biological ground-truthing. However, coastal areas are challenging to map with full spatial coverage due to the shallow water conditions. Furthermore, the research vessels often have too large drafts to sail in very shallow water close to the coastline. An alternative is to use airborne LiDAR technology. Topo-bathymetric LiDAR (green wavelength of 532&#160;nm) has made it possible to derive high-resolution data of the bathymetry in coastal zones (e.g. Andersen et al., 2017). This technology can cover the transition zone between land and water, and the time consumption for data acquisition is small compared to vessel borne methods. However, the processing of the data still requires manual decision steps, which makes it rather time consuming, and to some extent subjective.The aim of this study was to investigate the possibility of developing an automated method to classify stones from topo-bathymetric LiDAR data in coastal marine environments with shallow water (<6&#160;m). The R&#248;dsand lagoon in Denmark, where topo-bathymetric LiDAR data were acquired in 2015, was used as test. The classification was done using the random forest machine learning algorithm. The study resulted in the development of a nearly automated method to classify stones from topo-bathymetric LiDAR data. The classification accuracy was between 80 and 90% for the test site. The obtained knowledge about stone locations can provide important information about the ecosystem services and improved management of the coastal marine environment.&#160;Acknowledgement:This work is part of the project "ECOMAP - Baltic Sea environmental assessments by opto-acoustic remote sensing, mapping, and monitoring", supported by BONUS (Art 185), funded jointly by the EU and the Innovation Fund Denmark.&#160;ReferencesAndersen MS, Gergely A, Al-Hamdani Z, Steinbacher F, Larsen LR, Ernstsen VB (2017). Processing and performance of topobathymetric lidar data for geomorphometric and morphological classification in a high-energy tidal environment. Hydrology and Earth System Sciences, 21: 43-63, DOI:&#160;10.5194/hess-21-43-2017.

Download Full-text