A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhan...A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhance understanding of the ecosystem.We collected 126 individuals from 29 species,20 genera,17 families,three orders,and two classes using traditional gear.Perciforms were the dominant group in terms of species richness and biomass.The acoustic data indicated that very small(target strength[TS],dB) <-60 dB) and small(-60 dB≤TS<-45 dB) fish contributed the most to abundance and species richness on the coral reef,and that the proportion of medium-sized(-45 dB≤TS<-35 dB) and largesized(-35 dB≤TS) fish increased gradually as depth increased.The single-target detection method revealed two distinct size classes during the day in the 12-16 and 16-20-m layers.One group consisted of very smallsized fish(TS<-60 dB) and the other consisted of medium and large-sized fish(TS>-55 dB).The number of single-target detections was significantly higher during the night than during the day(P<0.05).The singletarget TS frequency distribution during the day was significantly different than during the night at depths of4-8,8-12,12-16,and 16-20 m.Significant differences were observed among the 4-8,8-12,12-16,and16-20-m-depth layers during day and night.Diel vertical movement was evidenced as fish began to spread and move upward just before sunset and began to assemble and descend shortly(15 min) after sunrise.展开更多
A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high t...A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high tension mooring by fixed flotation. The analysis was performed by using a Morison equation type finite element model configured with truss elements. Input forcing parameters into the model consisted of both regular and irregular waves, with and without a steady current. Heave, surge and pitch dynamic calculations of the reef structure were made. Tension response results of the attached mooring line were also computed. Results were analyzed in both the time and frequency domain in which appropriate, linear transfer functions were calculated. The influence of the current was more evident in the tension and heave motion response data. This is most likely the result of the large buoyancy characteristics of the reef structure and the length of the mooting cable. Maximum mooting component tension was found to be 13.9 kN and occurred when the reef was subjected to irregular waves with a co-linear current of 1.0 m/s velocity. The results also showed that the system had little damping （in heave） with damped natural periods of 2.8 s. This combination of system characteristics promotes a possible resonating situation in typical open sea conditions with similar wave periods.展开更多
In order to evaluate placement of artificial reefs in Huidong County and observe biological aggregating effect of fishery resources,background investigation and follow-up investigation were carried out for trawl fishi...In order to evaluate placement of artificial reefs in Huidong County and observe biological aggregating effect of fishery resources,background investigation and follow-up investigation were carried out for trawl fishing and gill-net fishing in Daxingshan artificial reef area.The biological resource density index(D),Margalef species richness index(R),Shannon-Winener diversity index(H'),and Pileou evenness index(J')were used to study diversity of water biological population and resource density.Trawl fishing investigation indicated that after placement of reefs,there was significant increase in quantity of species of nekton,total resource density,species richness index,and diversity index in reef area,which were 1.321,2.07,1.012 and 1.084 times the value before placement of reefs respectively.Gill-net fishing investigation indicated that after placement of reefs,the quantity of species of nekton,total resource density,species richness index,and diversity index in reef area were 2.571,7.976,2.399 and 2.667 times the value before placement of reefs respectively.After reef placement,fishes and crabs become dominant population.It showed that after reef placement,attraction effect of fishes is significant,community structure is obviously optimized,and water environment in reef area is significantly improved.Thus,it proved that the multiplication system through artificial reefs has been basically established in Daxingshan reef area of Huidong County.展开更多
Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma'an archipelago off the east coast of China, we evaluated impacts of five diffe...Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma'an archipelago off the east coast of China, we evaluated impacts of five different habitats(artificial reefs, mussel farms, cage aquaculture, rocky reefs and soft bottom) on fish assemblages. This study suggests that artificial reefs(AR) have significantly higher species richness, abundance and diversity than mussel farms(MF) or soft bottom(SB) habitats during most seasons, and that fish taxa in the AR habitats are similar to those in the rocky reef(RR) habitats. Two different fish assemblage patterns were revealed in the study area using non-metric multidimensional scaling ordination: an assemblage dominated by reef fishes(especially by Scorpaenidae species) in AR, RR and cage aquaculture(CA) habitats and an assemblage dominated by Sciaenidae species in MF and SB habitats. We suggest that reef fishes play a key role in differentiating fish community structures in the study area. Although few differences in fish abundance and diversity were found between the CA and SB habitats, a more diverse age structure was observed in the CA habitats. A much more complex fish assemblage and enhanced population of local species were established as a result of the presence of both floating and fixed artificial structures, probably through improved survival rates.展开更多
基金Supported by the National Key Technology Research and Development Program(No.2013BAD13B06)the Financial Project of the Ministry of Agriculture(No.NFZX2013)+1 种基金the Special Scientific Research Funds for Central Non-profit Institutes,Chinese Academy of Fishery Sciences(Nos.2014TS18,2013ZD03)the National Agricultural Finance Project "South China Sea Fishing Information Dynamic Acquisition"
文摘A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhance understanding of the ecosystem.We collected 126 individuals from 29 species,20 genera,17 families,three orders,and two classes using traditional gear.Perciforms were the dominant group in terms of species richness and biomass.The acoustic data indicated that very small(target strength[TS],dB) <-60 dB) and small(-60 dB≤TS<-45 dB) fish contributed the most to abundance and species richness on the coral reef,and that the proportion of medium-sized(-45 dB≤TS<-35 dB) and largesized(-35 dB≤TS) fish increased gradually as depth increased.The single-target detection method revealed two distinct size classes during the day in the 12-16 and 16-20-m layers.One group consisted of very smallsized fish(TS<-60 dB) and the other consisted of medium and large-sized fish(TS>-55 dB).The number of single-target detections was significantly higher during the night than during the day(P<0.05).The singletarget TS frequency distribution during the day was significantly different than during the night at depths of4-8,8-12,12-16,and 16-20 m.Significant differences were observed among the 4-8,8-12,12-16,and16-20-m-depth layers during day and night.Diel vertical movement was evidenced as fish began to spread and move upward just before sunset and began to assemble and descend shortly(15 min) after sunrise.
基金supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD)(KRF-2007-313-F00073)Technology Development Program for Food,Agriculture,Forestry and Fisheries,Republic of Korea
文摘A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high tension mooring by fixed flotation. The analysis was performed by using a Morison equation type finite element model configured with truss elements. Input forcing parameters into the model consisted of both regular and irregular waves, with and without a steady current. Heave, surge and pitch dynamic calculations of the reef structure were made. Tension response results of the attached mooring line were also computed. Results were analyzed in both the time and frequency domain in which appropriate, linear transfer functions were calculated. The influence of the current was more evident in the tension and heave motion response data. This is most likely the result of the large buoyancy characteristics of the reef structure and the length of the mooting cable. Maximum mooting component tension was found to be 13.9 kN and occurred when the reef was subjected to irregular waves with a co-linear current of 1.0 m/s velocity. The results also showed that the system had little damping （in heave） with damped natural periods of 2.8 s. This combination of system characteristics promotes a possible resonating situation in typical open sea conditions with similar wave periods.
基金National High-tech Research and Development Plan(863 Plan)Project(2006AA100303)National Public Benefit Program for Agriculture(201003068)
文摘In order to evaluate placement of artificial reefs in Huidong County and observe biological aggregating effect of fishery resources,background investigation and follow-up investigation were carried out for trawl fishing and gill-net fishing in Daxingshan artificial reef area.The biological resource density index(D),Margalef species richness index(R),Shannon-Winener diversity index(H'),and Pileou evenness index(J')were used to study diversity of water biological population and resource density.Trawl fishing investigation indicated that after placement of reefs,there was significant increase in quantity of species of nekton,total resource density,species richness index,and diversity index in reef area,which were 1.321,2.07,1.012 and 1.084 times the value before placement of reefs respectively.Gill-net fishing investigation indicated that after placement of reefs,the quantity of species of nekton,total resource density,species richness index,and diversity index in reef area were 2.571,7.976,2.399 and 2.667 times the value before placement of reefs respectively.After reef placement,fishes and crabs become dominant population.It showed that after reef placement,attraction effect of fishes is significant,community structure is obviously optimized,and water environment in reef area is significantly improved.Thus,it proved that the multiplication system through artificial reefs has been basically established in Daxingshan reef area of Huidong County.
基金supported by the National High Technology Research and Development Program of China (863 Program, No. 2006AA100303)the National Basic Research Program of China (No. 2011CB111608)partially supported by the Maine Sea Grant College Program at the University of Maine in the USA
文摘Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma'an archipelago off the east coast of China, we evaluated impacts of five different habitats(artificial reefs, mussel farms, cage aquaculture, rocky reefs and soft bottom) on fish assemblages. This study suggests that artificial reefs(AR) have significantly higher species richness, abundance and diversity than mussel farms(MF) or soft bottom(SB) habitats during most seasons, and that fish taxa in the AR habitats are similar to those in the rocky reef(RR) habitats. Two different fish assemblage patterns were revealed in the study area using non-metric multidimensional scaling ordination: an assemblage dominated by reef fishes(especially by Scorpaenidae species) in AR, RR and cage aquaculture(CA) habitats and an assemblage dominated by Sciaenidae species in MF and SB habitats. We suggest that reef fishes play a key role in differentiating fish community structures in the study area. Although few differences in fish abundance and diversity were found between the CA and SB habitats, a more diverse age structure was observed in the CA habitats. A much more complex fish assemblage and enhanced population of local species were established as a result of the presence of both floating and fixed artificial structures, probably through improved survival rates.
