Community composition,co-occurrence,and environmental drivers of bacterioplankton community in surface and 50-m water layers in the subarctic North Pacific

The Western Subarctic Gyre(WSG)is one of the two gyre-systems in the subarctic North Pacific known for high nutrient and low-chlorophyll waters.However,the bacterioplankton in marine water of this area,either in terms of the taxonomic composition or functional structure,remains relatively unexplored.A total of 22 sampling sites from two water layers(surface water,SW and 50-m layer water,FW)were collected in this area.The physiochemical parameters of waters,Synechococcus,and bacterial density,as well as the bacterioplankton community composition and distribution pattern,were analyzed.The nutrient concentrations of DIN,DIP,and DSi,Chl-a concentration,and the average abundance of heterobacteria in FW were higher than those in SW.However,temperature and the average abundance of Synechococcus and pico-eukaryotes were higher in SW.A total of 3269 OTUs were assigned,and 2123OTUs were commonly shared;moreover,similar alpha diversity patterns were observed in both SW and FW.The bacterioplankton community showed significantly obvious correlation with salinity,DIP,DIN,and Chl a in both SW and FW.Proteobacteria,Cyanobacteria,Bacteroidota,Actinobacteriota,and Firmicutes were the main phyla while Synechococcus_CC9902,Psychrobacter,and Sulfitobacter were the dominant genera in each sampling site.Most correlations that happened between the OTUs in the cooccurrence network were positive and inter-module.Higher edges and graph density were found in SW,indicating that more correlations occurred,and the community was more complex in SW.This study provided novel knowledge on the bacterioplankton community structure and the correlation characteristics in WSG.

Music stimulus has a positive eff ect on survival and development of the larvae in swimming crab Portunus trituberculatus

The sound stimulus has a signifi cant impact on marine animals.However,many studies have focused on the negative impacts of sound on marine vertebrates.The positive impacts of sound on marine animals,especially on marine invertebrates,were rarely studied.In the present study,we evaluated the eff ects of music on the survival and development of an economically important marine invertebrate,swimming crab Portunus trituberculatus.Three pieces of classical music and a control group,i.e.,Eine Kleine Nachtmusik by Mozart(EK),Bach-Violin Concerto No.1(BV),Anonymous Romanza by Anonymous(AR),and environmental sound(EN)were used.The sound pressure received were 163-dB root mean square(RMS)re 1μPa for EK,166-dB RMS re 1μPa for BV,165-dB RMS re 1μPa for AR,44-dB RMS re 1μPa for EN,respectively.The larvae were subject to 3-h classical music transmission every day during the entire larval development period.The result showed that BV and AR signifi cantly elevated the cumulative survival rate of the larva from 3.42%±1.77%(EN)to 10.65%±1.69%(BV)and 7.12%±1.37%(AR)respectively(P<0.05).Though music did not aff ect the cumulative development time of larvae from ZoeaⅠto ZoeaⅣ,it signifi cantly increased the molting rate of megalopa from 24.00%±11.78%(EN)to 44.00%±13.06%(AR)and 46.67%±10.50%(BV)(P<0.05).Musical exposure during critical growth intervals may contribute to the survival and development of larval crustaceans.From an application point of view,music intervention is much economically feasible.The observed music eff ects imply that music could further enhance growth,welfare,and production.