Zooplankton community response to eddy during dinoflagellate Noctiluca scintillans blooms off Pakistan,northern Arabian Sea

Eddies are major elements of ocean dynamics that affect ocean production.Understanding their effects on plankton distribution may help understand the dynamics of harmful phytoplankton blooms.Previous studies on the effects of eddies in the northern Arabian Sea have primarily focused on the zooplankton community,and few have observed zooplankton dynamics during winter blooms of Noctiluca scintillans.We investigated zooplankton community structure and the related environmental variability during a N.scintillans bloom that was affected by an eddy in February 2018.The sampling stations were deployed at eddy core and eddy edge distinguished in salinity,temperature,and velocity.Results show that N.scintillans bloomed at the eddy core with high-velocity currents induced by warm eddies that moved from eddy core to eddy edge.As a result,blooms significantly changed the zooplankton community structure.Non-bloom stations had higher zooplankton diversity than bloom stations.Zooplankton at non-bloom stations were dominated by either tunicates or copepods,such as Thalia democratica and Pleuromamma gracilis.In addition to the influence of N.scintillans blooms,the velocity of eddy currents was a crucial factor on the similarities in the zooplankton community composition between eddy edge and eddy core.Moreover,the lower abiotic factors in bloom area contribute to the structuring of the zooplankton community during N.scintillans blooms.

Coral reef ecological pump for gathering and retaining nutrients and exporting carbon:a review and perspectives

How coral reefs with high productivity and biodiversity can flourish in oligotrophic tropical oceans has inspired substantial research on coral reef ecosystems.Increasing evidence shows that similar to water in an oasis in the desert,there are stable nutrient supplies to coral reefs in oligotrophic oceans.Here,with emphasis on the fluxes of organic matter,we summarize at the ecosystem level(1)the multiple input pathways of external nutrients,(2)the storage of nutrients in reef organisms,(3)the efficient retaining and recycling of dissolved and particulate organic matter within coral reef ecosystems,(4)the distinctly high phytoplankton productivity and biomass inside and near oceanic coral reefs,and(5)the export of reef-related organic carbon to adjacent open oceans.These properties enable coral reefs to function as ecological“pumps”for gathering nutrients across ecosystems and space,retaining and recycling nutrients within the ecosystem,supporting high phytoplankton productivity,and exporting organic carbon to adjacent open oceans.Particularly,the high phytoplankton productivity and biomass make waters around coral reefs potential hotspots of carbon export to ocean depths via the biological pump.We demonstrate that organic carbon influx is vital for coral reef ecosystems’carbon budget and carbon export.The concept of the coral reef ecological pump provides a framework to improve the understanding of the functioning of the coral reef ecosystem and its responses to disturbance.Prospects of the coral reef ecological pump in coral reef studies are discussed in changing oceans driven by human activities and global change in the Anthropocene.

Vampyroteuthis pseudoinfernalis sp.nov.:the second extant widespread deep sea squid species of Vampyromorpha(Cephalopoda:Coleoidea)

The vampire squid,Vampyroteuthis infernalis Chun,1903,is currently the only extant species in the family Vampyroteuthidae Chun,1903.However,specimens from the Gulf of Guinea,Africa,and California suggested the possibility of additional taxa.Here,we report the second species of Vampyroteuthis,collected from the South China Sea,China,which differs from V.infernalis by its tail shape,lower beak,photophores position,and the phylogenetic analysis of mitochondrial COI and nuclear large subunit ribosomal DNA(LSU)sequences:V.infernalis present by the lacking of the tail,photophores located approximately one-third of the points between the fins and end,and the lower beak with a broad,short wing;V.pseudoinfernalis Qiu,Liu&Huang,sp.nov.present by an acuate tail,a pair of photophores located at the midpoints between the fins and tail,and a lower beak with a broad,elongate wing.

Cell Size Dependent Responses of Phytoplankton Assemblages to Nitrate and Phosphate Additions in Surface Waters of the Northern South China Sea

Bioavailability of nitrogen (N) and phosphorus (P) is known to affect marine phytoplankton physiology, thus influencing their primary productivity;and it’s of general interest to see how the N or/and P additions affect the differently cell-sized phytoplankton assemblages. Data from the northern South China Sea showed that P addition increased up to 6 times of total chl a content within 24 h in the estuarine water;and N+P addition increased more than 20 times of chl a within 144 h in the pelagic water. The P addition powered 18.0% and 149% increase in the carbon fixation of larger (>3 μm) and smaller (

Linking coral fluorescence phenotypes to thermal bleaching in the reef-building Galaxea fascicularis from the northern South China Sea

Coral fluorescence phenotypes have been suggested as an adaptation to a broad range of environmental conditions,yet the mechanisms linking thermal bleaching tolerance in reef-building coral populations,associated with fluorescence phenotypes due to GFP-like proteins,remains unclear.In this study,the relationship between the thermal sensitivity and phenotypic plasticity of corals was investigated using two phenotypes of Galaxea fascicularis,green and brown.The results reveal that brown G.fascicularis was more susceptible to bleaching than green G.fascicularis when exposed to a higher growth temperature of 32℃.Both phenotypes of G.fascicularis were associated with the thermotolerant Symbiodiniaceae symbiont,Durusdinium trenchii.However,the brown G.fascicularis showed a significant decrease in Symbiodiniaceae cell density and a significant increase in pathogenic bacteria abundance when the growth temperature was raised from 29 to 32℃.The physiological traits and transcriptomic profiles of Symbiodiniaceae were not notably affected,but there were differences in the transcriptional levels of certain genes between the two phenotype hosts of G.fascicularis.Under heat stress of 32℃,the gene encoding green fluorescent protein(GFP)-like and chromosome-associated proteins,as well as genes related to oxidative phosphorylation,cell growth and death showed lower transcriptional levels in the brown G.fascicularis compared to the green G.fascicularis.Overall,the results demonstrate that the green form of G.fascicularis is better able to tolerate ocean warming and defend against pathogenic bacteria,likely due to higher gene transcription levels and defense ability.

Progress in studies on the diversity and distribution of planktonic ciliates (Protista, Ciliophora) in the South China Sea

As an important component of microzooplankton,ciliates play a key role in matter cycling and energy fow in marine planktonic ecosystems.Studies of planktonic ciliate have been extensive in the South China Sea(SCS)over the last 20 years.Here,we summarize the recent progress on the diversity and distribution of this group in the SCS.This includes that in:(1)the waters covering the intertidal zone of the northern SCS,most studies have focused on taxonomy,with 71 species collected,identifed,and described(with~40%new species);(2)neritic waters distribution patterns have been examined at a regional scale,with ciliates displaying signifcant spatial variations and seasonal dynamics;(3)in oceanic waters,there has been a focus on ciliate distribution in north,centre,and south regions,where mesoscale physical processes play roles in controlling distributions,and noticeable vertical variations occur.More generally,some studies examine the infuences of environment variables on ciliates,and indicate that chlorophyll a concentration is commonly positively correlated with ciliates abundance.In addition,some signifcant fndings are summarized,the limitations of past studies are considered,and recommendations are made for future work on planktonic ciliates in SCS.