Phylogenetic analysis of the genusdendmnephthya(nephtheidae, alcyonacea) based on internal transcribed spacer sequences of nuclear rDNA

First report of bioaccumulation and bioconcentration of aliphatic hydrocarbons (AHs) and persistent organic pollutants (PAHs, PCBs and PCNs) and their effects on alcyonacea and scleractinian corals and their endosymbiotic algae from the Persian Gulf, Iran: Inter and intra-species differences

The coral reefs of the Persian Gulf are the most diverse systems of life in the marine environment of the Middle East. Unfortunately, they are highly threatened by local and global stressors, particularly oil pollutants. This is the first quantitative and qualitative study aimed at assessing the concentration and sources of n-alkanes and POPs (PAHs, PCBs and PCNs) in coral tissues, symbiotic algae (zooxanthellae), reef sediments and seawaters in coral reefs of Lark and Kharg in the Persian Gulf, Iran. This work was conducted on eight species of six genera and three families of hard corals and one family of soft coral. A significant variation in the concentration of ∑30n-alkanes and POPs (∑40PAHs, ∑22PCBs and 20PCNs) was found in the decreasing order: zooxanthellae > coral tissue > skeleton > reef sediment > seawater. The bioaccumulation of these compounds was 2-times higher in ahermatypic than in hermatypic corals, among which significant variations were observed in both sites. In Kharg, Porites lutea had the highest mean concentration of ∑30n-alkanes and ∑40PAHs in soft tissue, whereas the lowest values were in Platygyra daedalea. A contrasting trend was documented for ∑22PCBs and 20PCNs, with the highest level reported in soft tissue of P. daedalea and the lowest in P. lutea at Kharg. Compositional pattern of AHs and PAHs demonstrated the predominance of LMW-PAHs and n-alkanes. In skeleton and reef sediments, tetra, penta and tri-CBs were the most abundant PCBs congeners followed by di-CB > hexa-CB > hepta-CB > octa-CB,whiletri-CB > di-CB > tetra-CB > penta-CB > hexa-CB > hepta-CB > octa-CB was observed for soft tissue, zooxanthellae and seawater. The results of RAD test indicated significantly negative correlation between total concentration of these compounds with zooxanthellae density, the chlorophyll-a and C₂ in corals at both reefs. This is the first report on levels, health assessment and source apportionments of POPs in zooxanthellae and a first step in the implementation of specific coral reef management measures.

Molecular phylogenetic insights into the evolution of Octocorallia: a review

The anthozoan sub-class Octocorallia, comprising approximately 3000 species of soft corals, gorgonians, and sea pens, remains one of the most poorly understood groups of the phylum Cnidaria. Efforts to classify the soft corals and gorgonians at the suprafamilial level have long thwarted taxonomists, and the subordinal groups in current use are widely recognized to represent grades of colony forms rather than clades. Molecular phylogenetic analyses of the sub-class do not support either the current morphologically based subordinal or familial-level taxonomy. To date, however, the resolution necessary to propose an alternative, phylogenetic classification of Octocorallia or to elucidate patterns of morphological evolution within the group is lacking. Attempts to understand boundaries between species and interspecific or intraspecific phylogenetic relationships have been hampered by the very slow rate of mitochondrial gene evolution in Octocorallia, and a consequent dearth of molecular markers with variation sufficient to distinguish species (or sometimes genera). A review of the available ITS2 sequence data for octocorals, however, reveals a yet-unexplored phylogenetic signal both at sequence and secondary-structure levels. In addition, incongruence between mitochondrial and nuclear gene trees suggests that hybrid speciation and reticulate evolution may be an important mechanism of diversification in some genera. Emerging next-generation genomic-sequencing technologies offer the best hope for a breakthrough in our understanding of phylogenetic relationships and of evolution of morphological traits in Octocorallia. Genome and transcriptome sequencing may provide enough characters to resolve relationships at the deepest levels of the octocoral tree, while simultaneously offering an efficient means to screen for new genetic markers variable enough to distinguish species and populations.