16S rRNA is a better choice than COI for DNA barcoding hydrozoans in the coastal waters of China

Identification of hydrozoan species is challenging, even for taxonomic experts, due to the scarcity of distinct morphological characters and phenotypic plasticity. DNA barcoding provides an efficient method for species identification, however, the choice between mitochondrial cytochrome c oxidase subunit I（COI） and large subunit ribosomal RNA gene（16S） as a standard barcode for hydrozoans is subject to debate. Herein, we directly compared the barcode potential of COI and 16S in hydrozoans using 339 sequences from 47 pelagic hydrozoan species. Analysis of Kimura 2-parameter genetic distances（K2P） documented the mean intraspecific/interspecific variation for COI and 16S to be 0.004/0.204 and 0.003/0.223, respectively. An obvious ＂barcoding gap＂ was detected for all species in both markers and all individuals of a species clustered together in both the COI and 16S trees. These results suggested that the species within the studied taxa can be efficiently and accurately identified by COI and 16S. Furthermore, our results confirmed that 16S was a better phylogenetic marker for hydrozoans at the genus level, and in some cases at the family level. Considering the resolution and effectiveness for barcoding and phylogenetic analyses of Hydrozoa, we strongly recommend 16S as the standard barcode for hydrozoans.

Fouling characteristics of cnidarians(Hydrozoa and Anthozoa)along the coast of China

Hydrozoans and anthozoans are an important component of a great variety of marine communities,particularly abundant and ubiquitous as part of the fouling assemblages around the globe.Several negative impacts have been associated to their occurrence on artificial substrata.In the coastal waters of China,a total of 76 species of fouling cnidarians were observed and classified.According to the occurrence frequency or biomass,the major species in the Bohai and Yellow Seas were Ectopleura marina,Bougainvillia sp.,and Eudendrium capillare;in the East China Sea Anthopleura nigrescens,Diadumene lineata,and Ectopleura crocea;and in the South China Sea Clytia sp.,Obelia sp.,and Actiniaria spp.The peak period of settlement of most species was mainly in summer and autumn.With the decrease of latitude,species number increased greatly and even cnidarian fouling was observed all year round in the East and South China Seas.Salinity was another factor aff ecting species distribution.Naturally,immersion time of substrata also directly aff ects the characteristics of cnidarians in fouling communities.

Mass Beach Stranding of Blue Button Jellyfishes,Porpita porpita(Linnaeus 1758)from the Coast of Mandvi,Kutch,India during August,2021

Present short communication reports about beach stranding of Porpita porpita(Linnaeus 1758)from the Coast of Mandvi,Kutch during August 2021.Also,this is the first record of the blue button jellyfishes for the northern Gulf of Kutch region.A study was carried out by primary observation and measurements of common environmental parameters such as Sea Surface Temperature(SST),Wind Direction&Wind Speed.Aboral and oral parts were observed and described.It is assumed that the large biomass of blue button jellyfish on the beach is due to strong shoreward Monsoon winds.

Ecological succession of benthic organisms on niche-type artificial reefs

As part of efforts to restore fishery resources and recover damaged coastal ecosystems,artificial reefs are often anchored on the seafloor in coastal zones,to provide new habitats for marine organisms.The aim of the study was to describe the structure of a community of benthic invertebrates colonising a niche-type artificial reef(AATN in Spanish).Nine structures were anchored at depths of 16±1.5 m for 99 weeks(22 months)in the Area of Benthic Resource Management and Exploitation(AMERB)in coastal waters of the Region of Bio Bio,Chile.The results showed that,at 3 months from submersion of the NTAR,much of the artificial substrate remained bare and there were only low levels of specimens of Balanus sp.barnacles,showing mean coverage of 11.26%,and even lower proportions of Rhodophyta,with mean coverage of 0.34%.At 6 months,the presence of hydrozoans was seen,decreasing the coverage of the barnacles,which was aided further at 8 months with the arrival of barnacle predatory invertebrates.At 8 months,new benthic invertebrates appeared and competed for the substrate.These included sponges and algae.At 99 weeks,the hydrozoans dominated the substrate,followed by barnacles and Rhodophyta,the first colonising organisms,leading to colonisation by motile macro-invertebrates,mainly consisting of crustaceans,echinoderms and molluscs.The AATN artificial system provides an ideal substrate for the development of early ecological succession and the use of this technology should be feasible in the recovery process of habitat damaged by anthropogenic actions and climate change.