Comprehensive Circulation and Water Quality Investigation of the Coastal Lagoon: Puerto Galera, the Philippines

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

SYNERGISTIC METHODS IN REMOTE SENSING DATA ANALYSIS FOR TROPICAL COASTAL ECOSYSTEMS MONITORING

Tropical coastal environments around the world have undergone rapid changes which made consequent of their ecosystems degradation inevitable. Despite numerous attempts to map their extent and distribution from space, the ability to relate the surface signals reflected and subsequently measured by remote imaging sensors to the biophysical characteristics of coastal habitat targets have been given inadequate attention. The dynamic characteristic of the coastal shallow water areas including tidal and wave forcing, water quality and environmental stresses, both natural and anthropogenic complicate this task. Hence there is a need to consider these factors in understanding images obtained from different sources taken at various periods. This research focuses on synergistic methods in multi-source image processing for assessing benthic coastal habitats such as corals, seagrass, and algae by examining image data covering these types of environment from space through the aid of theoretical remote sensing approaches. Our study area covers the Fukido river mouth area and Shiraho reef of Ishigaki Island located in southern Ryukus, Japan. Images were acquired from satellite-borne Ikonos, SPOT, ASTER and Landsat respectively in 2002. Principles of BRDF (bidirectional reflectance distribution functions) modelling, shallow water optics and radiative transfer have been utilized to explain shallow water reflectance values with biophysical properties such as distribution, abundance, morphology and depth as controlling parameters. To reinforce parameterizations and to validate computational results, field surveys were conducted to gather in-situ data including water quality (mainly chlorophyll-a and turbidity), sea surface conditions, benthic habitat cover, abundance and distribution, some of which are synchronous with image acquisition. Spectral profiles across the reef area benthic cover were also used for calibrating reflectance

Complete mitochondrial genome sequences for Crown-of-thorns starfish Acanthaster planci and Acanthaster brevispinus

BACKGROUND: The crown-of-thorns starfish, Acanthaster planci (L.), has been blamed for coral mortality in a large number of coral reef systems situated in the Indo-Pacific region. Because of its high fecundity and the long duration of the pelagic larval stage, the mechanism of outbreaks may be related to its meta-population dynamics, which should be examined by larval sampling and population genetic analysis. However, A. planci larvae have undistinguished morphological features compared with other asteroid larvae, hence it has been difficult to discriminate A. planci larvae in plankton samples without species-specific markers. Also, no tools are available to reveal the dispersal pathway of A. planci larvae. Therefore the development of highly polymorphic genetic markers has the potential to overcome these difficulties. To obtain genomic information for these purposes, the complete nucleotide sequences of the mitochondrial genome of A. planci and its putative sibling species, A. brevispinus were determined and their characteristics discussed. RESULTS: The complete mtDNA of A. planci and A. brevispinus are 16,234 bp and 16,254 bp in size, respectively. These values fall within the length variation range reported for other metazoan mitochondrial genomes. They contain 13 proteins, 2 rRNA, and 22 tRNA genes and the putative control region in the same order as the asteroid, Asterina pectinifera. The A + T contents of A. planci and A. brevispinus on their L strands that encode the majority of protein-coding genes are 56.3% and 56.4% respectively and are lower than that of A. pectinifera (61.2%). The percent similarity of nucleotide sequences between A. planci and A. brevispinus is found to be highest in the CO2 and CO3 regions (both 90.6%) and lowest in ND2 gene (84.2%) among the 13 protein-coding genes. In the deduced putative amino acid sequences, CO1 is highly conserved (99.2%), and ATP8 apparently evolves faster any of the other protein-coding gene (85.2%). CONCLUSION: The gene arrangement, base composition, codon usage and tRNA structure of A. planci are similar to those of A. brevispinus. However, there are significant variations between A. planci and A. brevispinus. Complete mtDNA sequences are useful for the study of phylogeny, larval detection and population genetics

Observations of velocities, sand concentrations, and fluxes under velocity-asymmetric oscillatory flows

Peer reviewedPublisher PD

Hydrodynamics across seagrass meadows and its impacts on Indonesian coastal ecosystems: A review

Seagrass canopies are important components of the world’s coastal environments providing critical ecological services. Nearshore hydrodynamics, i.e., waves and currents, are essential in controlling the ecological processes across coastal environments. Seagrass meadows can impose more complex hydrodynamics processes by attenuating sea-swell waves and decreasing the impact of nearshore mean water level rise due to wave setup and Infragravity (IG) waves. Consequently, the seagrasses dissipate waves and reduce flows allowing sediments to settle and accrete the shorelines. However, despite their significant roles, knowledge of hydrodynamics in the Indonesian seagrass ecosystems is relatively limited compared to other coastal ecosystems such as sandy beaches, mangroves, and coral reefs. This review highlights the dynamics of waves and currents, and their interaction with sediment transport and ecological processes, including biogeochemical and dispersal processes on the seagrass ecosystem contributing to the existing seagrass research in Indonesia. The associated literature is collected from scientific databases such as Scopus and Google Scholar that range between 1965 and 2021. The result showed that most of the research on hydrodynamic in seagrass ecosystems was carried out in temperate zones. Until recently, there have been limited publications discussing the interaction between the Indonesian (tropical) seagrass ecosystem and hydrodynamics parameters, even though the region has abundant seagrass species. Moreover, Indonesia is strongly influenced by various atmospheric-oceanic forcing, including the Asian monsoon affecting the dynamic of the coastal area with seagrass ecosystems. At a canopy scale, the correlation between the nearshore (tropical) hydrodynamics and ecological processes in the system is yet to be explored. Considering the potential benefit of seagrasses to coastal ecosystems, developing future research in hydrodynamics across the ecosystem is critical to overcoming the knowledge gaps in Indonesia. The knowledge gained could support the Indonesian seagrass ecosystem services and their resilience to potential hazards and climate change

Using modal decompositions to explain the sudden expansion of the mixing layer in the wake of a groyne in a shallow flow

The sudden expansion of the mixing layer created in the wake of a single groyne is investigated using Particle Image Velocimetry (PIV). In the region of the sudden expansion a patch of high Reynolds shear stresses are observed. Using low-order representations, created from a Dynamic Mode Decomposition and a search criteria based on a Proper Orthogonal Decomposition, the spatio-temporal mechanism of the sudden expansion is investigated. The present study demonstrates the sudden expansion is created by the periodic merging of eddies. These eddies originate from the upstream separation and the tip of the groyne and merge with recirculating eddies created, downstream of the groyne, at the interface of the mixing layer and the lateral wall

Modified Shallow Water Equations for significantly varying seabeds

In the present study, we propose a modified version of the Nonlinear Shallow Water Equations (Saint-Venant or NSWE) for irrotational surface waves in the case when the bottom undergoes some significant variations in space and time. The model is derived from a variational principle by choosing an appropriate shallow water ansatz and imposing some constraints. Our derivation procedure does not explicitly involve any small parameter and is straightforward. The novel system is a non-dispersive non-hydrostatic extension of the classical Saint-Venant equations. A key feature of the new model is that, like the classical NSWE, it is hyperbolic and thus similar numerical methods can be used. We also propose a finite volume discretisation of the obtained hyperbolic system. Several test-cases are presented to highlight the added value of the new model. Some implications to tsunami wave modelling are also discussed.Comment: 34 pages, 18 figures, 65 references. Other author's papers can be downloaded at http://www.denys-dutykh.com