Inquiries regarding the use of the book should be addressed to the Rights and Permissions Department of INTECHOPEN LIMITED ([email protected]). He was dean of graduate students in the marine science program and was head of the benthic ecology laboratory.
Introduction
The benthic realm
This concise chapter explores the relationships of benthic community structure facing a complex physical environment associated with human impacts. The relative shallowness of the shelf facilitates the recycling process and is the structural cause of the high biomass found.
The southeast Brazilian continental shelf: physical environment and nutrient sources
In most of the southeastern Brazilian continental shelf, water movement is driven on different time scales by wind, the Brazil Current (BC) and tides [1]. A diagrammatic model of biological and physical interactions for the continental shelf of southeastern Brazil is shown in Figure 2.
Food supply to the benthic system
Compositional differences indicate, for example, the source of organic matter present at the bottom of the shelf. The results identified the quality and quantity of organic matter as the main determinants of benthic community structure.
Benthic studies on the southeast Brazilian continental shelf
Sediment is then needed in the first and crucial phase of the species' life cycle. Spatial and temporal changes in macrofauna communities have been intensively studied on the plateau of São Paulo State, the central part of the SBB.
Conclusion
The thermal front formed in the frontal zone between South Atlantic Central Water and the shallow Coastal Water is responsible for the concentration of an extremely dense population of the swimming crab P. Finally, in the E Gulf of Mexico, the progress in the studies of the benthic zone.
Methodology
- Sampling
- Sample treatment
- Sample analysis
- Ancillary data
This isotopic fractionation (or discrimination), although small, is measurable, and in a mixture of isotopes of the same element, the lighter isotope (such as 12C) is generally favored in the reaction products, leaving the heavier isotope (13C) in the reactant. Stable carbon and nitrogen isotopes were analyzed in suspended particles collected in the water columns, sediments and animal matrices.
Results and discussion
- Carbon apportionment in a bay of Campeche oil seep
- Carbon and nitrogen sources to the benthic food web in the bay of Campeche oil field region
- Organic carbon and nitrogen sources to NW Cuba deep-sea sediments In the E Gulf of Mexico, Cuba’s NW sector (Figure 1), localized between the
- Oil-related baseline levels of a Bank of Campeche coral reef
Bottom panel: Depth distribution of (c) total hydrocarbon concentration and (d) δ13C values from the reference and seepage sites. The study zone is located in the transition zone between the carbonate and terrigenous sediments of the Bay of Campeche continental shelf [34] and extends from nearshore sampling sites along the Coatzacoalcos and Grijalva-Usumacinta rivers to the 60 m-deep isobath in the oil drilling zone 1 (Figure). Histograms of the isotopic composition of particulate organic carbon (δ13C-POC) and particulate nitrogen (δ15N-PN) for the coastal region (upper panel) and Cantarell oil field region (lower panel).
Conclusions
Geochemistry of marine sediments associated with gas pockets and seeps in the Gulf of Mexico. Regional differences in nitrogen and carbon isotopes on the continental shelf of the Gulf of Mexico. Benthic macroinvertebrate communities as indicators of environmental health of the Cunas River in.
Materials and methods
Description of study area
However, the altitudinal gradient is also considered a determining factor in the distribution of these communities [7]. Although some authors point out that both temperature and oxygen partial pressure are key factors in the distribution of benthic macroinvertebrate communities in river systems [8]. This study focuses on the Cunas River, one of the most important rivers in the Mantaro River Basin in the Central Andes of Peru.
Sample collection and analysis
The Cunas River is located in the central highlands of Peru, in the Mantaro River watershed. It is located in the provinces of Chupaca, Concepción, Huancayo and Jauja in the Junín region. In the Cunas River, three sampling sectors were defined, according to the area's representation in terms of the impact of anthropic activity.
Statistical analysis
Results
Water quality based on physical, chemical, and bacteriological indicators The pH of the water presented means and standard deviation that oscillated
The anthropogenic pressure experienced by the water bodies in the sampling Progress in the studies of the benthic zone. Mean and standard deviation of water quality indicators for the Cunas River, according to population center and climatic season. Perceptual map of principal component analysis (PCA) based on the water quality indicators of the river Cunas.
Spatial and temporal variation of benthic macroinvertebrate communities A total of 26 families of benthic macroinvertebrates were found during the two
Principal coordinate analysis (PCO) based on the number of families and the abundance of benthic macroinvertebrates in the three sampling sectors according to the sampling season. Nonmetric multidimensional scaling analysis of benthic macroinvertebrate richness and abundance in three sampling sectors by sampling season. However, during the rainy season, Chironomidae reached the highest percentage contribution in the composition of the benthos.
Relationship of water quality and variation patterns of benthic macroinvertebrate communities
Regarding diversity indicators, the San Blas sector presented the highest richness and diversity. The results also show that the most dominant family in the Huarisca and La Perla sectors was Chironomidae, with high percentages of contribution in both sampling periods (Table 2).
Discussion
Water quality based on physical, chemical, and bacteriological indicators The results obtained from the evaluation of water quality in the sampling sectors
The result of the distance-based redundancy analysis (dbRDA) of the variables of water quality and relative abundance of benthic macroinvertebrates is presented in Figure 7. Analysis of the canonical correspondence of the variables of water quality and diversity of benthic macroinvertebrates of the river Cunas. Perceptual map of the distance-based redundancy analysis (dbRDA) of better physico-chemical predictors on the composition of benthic macroinvertebrate communities in the river Cunas.
Spatial and temporal distribution of benthic macroinvertebrate communities
This condition of the river in these sectors would affect the composition of benthic macroinvertebrate communities. Heidi De la Cruz performed the determination of physico-chemical parameters on site and in the laboratory. In calcareous species of the class Hydrozoa, their skeletons are composed of calcite, aragonite, or both (Table.
Skeletogenesis and OA
Implications, threats, and consequences of OA
In the Hydrozoa class, three types of skeletogenesis exist, and the main minerals involved are the CaCO3. However, no reduction in the calcification process was observed in Millepora platyphylla despite exposure to osteoarthritis conditions [46]. The zooxanthellae are essential for the "fire corals" to achieve their calcification process, to keep their calcification rate constant and to accelerate a calcification in function of the environmental conditions [43].
Conclusion
Of the three families of extant calcareous hydroids, only “fire corals” have a symbiotic relationship with zooxanthellae [ 42 ]. Genetic relationships of the hydrocoral Millepora alcicornis and its symbionts within and between sites across the Atlantic. Corals are one of the most important habitat formers of the Mediterranean mesophotic and aphotic zones, which constitute vulnerable marine ecosystems (VMEs) intended as those populations, communities or habitats that may be vulnerable to impacts of fishing activities [12].
Mesophotic and deep-sea vulnerable marine ecosystems
- Coralligenous
- CWC frameworks
- Coral forests
- Sea pen fields
Further sensitive habitats of the mesophotic and aphotic zones are mostly covered by the so-called In [25], the first estimate of the number of species associated with coral-like formations is made, with approximately 1670 species. Ecosystem goods and services provided by the mesophotic and deep-sea vulnerable habitats of the Mediterranean characterized by corals.
Conservation status
Advances in benthic zone studies. with only a few specimens of single sleractinians recorded) [89] and the FRA of the Nile Delta is characterized by the presence of chemosynthetic fauna (Figure 2). Effects of deep-water coral reefs on the abundance and size structure of megafauna in the Mediterranean Sea. The distribution and behavior of deep-sea benthopelagic fauna was observed using towed cameras in the cold-water coral province of Santa Maria di Leuca.
Mitochondrial gene organization and expression in hexacorals Five common features in the gene organization can be drawn from the 200
Order-specific gene organization
Mitochondrial gene organization and expression in hexacorals Five common features of gene organization can be drawn from the 200. The latter example involves a dramatic shift in the size of mitochondrial group I introns in Hexacorals are regulatory genetic elements. The most dramatic mitochondrial genome rearrangement is seen in the deep-water sea anemone Protanthea [16].
Mitochondrial RNA in hexacorals
Mitochondrial gene order is highly scrambled compared to the primary arrangement of sea anemones. Phylogenetic analysis suggests that MCh-II is horizontally transferred to Protanthea from the distantly related sea anemone [ 16 ]. Similarly, patterns of Bolocera samples at 40 m (Atlantic Ocean) [12] and at 1100 m (Pacific Ocean) [5] contain the same primary arrangement of sea anemones.
An obligatory group I intron in the ND5 gene
The ND5-717 intron is a giant group I intron
These rearrangements appear complex and involve a drastic reduction in the size of the ND5-717 intron from approximately 18 kb (primary rearrangement) to 12 kb and 10 kb, respectively ( Figure 2B ). The size of the ND5-717 intron increased from approximately 2 kb (major arrangement of sea anemones) to 15 kb in Protanthea (Appendix Table 1). RNA secondary structure folding of the ND5-717 ribozyme reveals that the catalytically important ωG (last nucleotide of the intron) is replaced by ωA (Figure 3).
Unconventional splicing of ND5-717 introns
The ND5-717 intron in sponge corals represents the largest group I intron known to date, with an approximate size of 19 kb. The longest forms of ND5-717 introns (approximately 15–19 kb) found in sponge corals [ 28 , 30 ] and the deep-water Protanthea sea anemone [ 6 ] contain almost the entire mitochondrial genome in P8. How the ND5-717 introns in stony corals are removed from their precursors by splicing is currently not known.
Mobile-type group I introns in the COI gene
Three different insertion sites in the COI gene
This is the first example of a natural group I intron removed by backsplicing and may explain why some hexacoral giants ND5-717 tolerate group I introns. These introns (sizes of about 6–12 kb) [ 19 , 39 ] may be too large and complex to be removed by conventional cis -splicing, and the ND5 exons may be too far apart for reverse splicing. An interesting idea is that group I intron transsplicing has been reported in mitochondrial transcripts of placozoans [40].
Expression of intron-encoded homing endonucleases
The HEG, which covers most of the intron sequences (including the ribozyme-encoded parts), is fused in-frame to the 50COI exon. Note that the HEG stop codon (UAG; red box) refers to the last three nucleotides of the intron. Note that the HEG initiation codon (AUG; green box) and stop codon (UAG; red box) are located at the 50-end and 30-end of the intron sequence, respectively.
Concluding remarks
Appendix
The group I introns in the COI gene encode LAGLIDADG-type homing endonucleases, consistent with intron mobility between related intronless alleles [ 12 , 45 ]. We thank current and former members of the research teams at the Genomics Group (Nord University) and the RNA Group (UiT—The Arctic University of Norway) for discussion and support. Two mitochondrial group I introns in a metazoan, the sea anemone Metridium senile: One intron contains genes for subunits 1 and 3 of NADH dehydrogenase.
![Table 5 gives concentrations of individual and total PAH concentrations (ΣPAH) in coral and sponge samples from this study and for three potential hydro-carbon sources in the region [57]](https://thumb-ap.123doks.com/thumbv2/1libvncom/9201059.0/53.765.114.640.84.1033/table-concentrations-individual-concentrations-σpah-samples-potential-sources.webp)
