A New Discovery of Deep-Water Benthic Organisms from the Southwestern Dongsha Area,South China Sea

Dongsha waters are poorly studied for gas hydrates. Previous multi-channel seismic reflection and Chirp sub- bottom profiles show that numerous submarine mounds stand up to 100 m high above the seafloor over the continental slope of the SW Dongsha Island in northern margin of the South China Sea （SCS）. These mounds are characterized by hardened seabed, seafloor gas venting and folded structures, which implies the existence of active mud volcanoes. This work aims to confirm this speculation by seafloor sample dredging and to explore the potential of gas hydrates.

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.

The Dietary Importance of Kelp-Derived Detritus to Pelagic and Benthic Consumers along the West Coast of Vancouver Island, Canada

Stable isotope analysis was used to determine the relative dietary importance of kelp-derived detritus to plankton and benthic organisms along a gradient of kelp abundance driven by recovering sea otter populations along the west coast of Vancouver Island (WCVI), Canada. The study used region-specific kelp isotope values (δ13C and δ15N) and season-specific phytoplankton isotope values to model dietary contributions of kelp-derived detritus (KDD). In general, KDD contributions were moderate to high in most plankton size fractions during the summer and decreased during the winter, particularly in the kelp sparse region. Hypothesized regional and spatial (distance from the coast) differences in kelp detritus contributions to zooplankton were not evident. Modeled estimates of the KDD contribution to benthic invertebrates were high (>40%) and independent of the organism size, among regions and between seasons, with the exception of Astraea gibberosa in the kelp abundant region. Local oceanography, natural kelp isotope signature variation, and significant overlap between kelps’ and blooming phytoplankton isotope values led to a large uncertainty in the assessed KDD contributions in benthic organisms. These results highlighted the importance of the KDD as a widespread and stable year-round food source in coastal kelp populated regions.

The accumulation and toxicity of ZIF-8 nanoparticles in Corbicula fluminea

Metal-organic frameworks(MOFs)are promising new materials that have been intensively studied and possibly applied to various environmental remediation.However,little is known about the fate and risk of MOFs to living organisms in thewater environment.Here,the toxic effects of ZIF-8 nanoparticles(NPs)on benthic organisms were confirmed by sub-chronic toxicity experiments(7 and 14 days)using Corbicula fluminea as the model organism.With exposure doses ranging from 0 to 50 mg/L,ZIF-8 NPs induced oxidative stress behaviors similar to the hormesis effect in the tissues of C.fluminea.The oxidative stress induced by ZIF-8 NPs and the released Zn^(2+)was the crucial cause of the toxic effects.Besides,we also found that the ZIF-8 NPs and dissolved Zn^(2+)may result in different mechanisms of toxicity and accumulation depending on the dosages.The Zn^(2+)release rate of ZIF-8NPswas high at low dosages,leading to a higher proportion of Zn^(2+)taken up by C.fluminea than the particulate ZIF-8.Conversely,at high dosages,C.fluminea mainly ingested the ZIF-8 NPs and resulted in increased mortality.The results have important implications for understanding the fate and biological effects of ZIF-8 in natural aquatic environments.