The first and second internal transcribed spacer(ITS1 and ITS2)regions of the ribosomal DNA from four species,Meretrix meretrix L.,Cyclina sinensis G,Mercenaria mercenaria L.,and Protothaca jedoensis L.,belonging to t...The first and second internal transcribed spacer(ITS1 and ITS2)regions of the ribosomal DNA from four species,Meretrix meretrix L.,Cyclina sinensis G,Mercenaria mercenaria L.,and Protothaca jedoensis L.,belonging to the family Veneridae were amplified by PCR and sequenced.The size of the ITS1 PCR amplification product ranged from 663 bp to 978 bp,with GC contents ranging from 60.78%to 64.97%.The size of the ITS1 sequence ranged from 585 bp to 900 bp,which is the largest range reported thus far in bivalve species,with GC contents ranging from 61.03%to 65.62%.The size of the ITS2 PCR amplification product ranged from 513 bp to 644 bp,with GC contents ranging from 61.29%to 62.73%.The size of the ITS2 sequence ranged from 281 bp to 412 bp,with CJC contents ranging from 65.21%to 67.87%.Extensive sequence variation and obvious length polymorphisms were noted for both regions in these species,and sequence similarity of ITS2 was higher than that of ITS 1 across species.The complete sequences of 5.8S ribosomal RNA gene were obtained by assembling ITS 1 and ITS2 sequences,and the sequence length in all species was 157 bp.The phylogenetic tree of Veneridae clams was reconstructed using ITS2-containing partial sequences of both 5.8S and 28S ribosomal DNA as markers and the corresponding sequence information in Arctica islandica as the outgroup.Tree topologies indicated that P jedoensis shared a close relationship with M.mercenaria and C sinensis,a distant relationship with other species.展开更多
Clams of the family Veneridae in northwest Mexico have traditionally been exploited by small-scale fisheries.Despite their socioeconomic importance for coastal communities in the region,most catch zones are currently ...Clams of the family Veneridae in northwest Mexico have traditionally been exploited by small-scale fisheries.Despite their socioeconomic importance for coastal communities in the region,most catch zones are currently in decline due to a lack of harvest control regulations that would impede the depletion of local fishing banks.In Puerto Libertad,in the northern reaches of the Gulf of California,banks of commercially unexploited clam species,including Megapitaria aurantiaca,M.squalida and Dosinia ponderosa,were discovered.The adequate management and exploitation of these banks requires developing basic knowledge regarding the abundance of the species and establishing reference points to determine clear,simple harvest regulations.The goal of this study was to identify population abundance in these banks and ascertain the parameters of the life history of the species found there in order to propose a harvest strategy that will allow the sustainable exploitation of this resource.A total of 288 transects were conducted in the two clam banks to identify species density.Abundance was determined using a geostatistical method.The relative cohort biomass-at-length was estimated to evaluate the effect of different lengths of first capture on the remaining biomass.Based on these data,two harvest control regulations were proposed:a maximum catch(Cmax)of 10%of the total estimated biomass,and a minimum optimal catch size(Lc).The abundance estimates were M.squalida(266,293-381,881 individuals);D.ponderosa(2,779,100-3,455,597);and M.aurantiaca(408,783-447,391).The harvest control regulations proposed are:M.squalida,Cmax=2.98 t and Lc=50.33 mm;D.ponderosa,Cmax=49.67 t and Lc=103.44 mm;and M.aurantiaca,Cmax=15.87 t and Lc=80.85 mm.These results are important as reference information for implementing harvest strategies in clam-fishing banks,and as a contribution to the management and sustainable exploitation of fisheries in the region.展开更多
基金supported by the 10th Five Years Key Programs for Sciences and Technology Development of China(No.2004BA526B0403)National Natural Science Foundation of China(No.Z2004024)Start—up Package Program for Attract—ing Talented People(No.KK03035)from Huaihai Institute of Technology(HHIT).
文摘The first and second internal transcribed spacer(ITS1 and ITS2)regions of the ribosomal DNA from four species,Meretrix meretrix L.,Cyclina sinensis G,Mercenaria mercenaria L.,and Protothaca jedoensis L.,belonging to the family Veneridae were amplified by PCR and sequenced.The size of the ITS1 PCR amplification product ranged from 663 bp to 978 bp,with GC contents ranging from 60.78%to 64.97%.The size of the ITS1 sequence ranged from 585 bp to 900 bp,which is the largest range reported thus far in bivalve species,with GC contents ranging from 61.03%to 65.62%.The size of the ITS2 PCR amplification product ranged from 513 bp to 644 bp,with GC contents ranging from 61.29%to 62.73%.The size of the ITS2 sequence ranged from 281 bp to 412 bp,with CJC contents ranging from 65.21%to 67.87%.Extensive sequence variation and obvious length polymorphisms were noted for both regions in these species,and sequence similarity of ITS2 was higher than that of ITS 1 across species.The complete sequences of 5.8S ribosomal RNA gene were obtained by assembling ITS 1 and ITS2 sequences,and the sequence length in all species was 157 bp.The phylogenetic tree of Veneridae clams was reconstructed using ITS2-containing partial sequences of both 5.8S and 28S ribosomal DNA as markers and the corresponding sequence information in Arctica islandica as the outgroup.Tree topologies indicated that P jedoensis shared a close relationship with M.mercenaria and C sinensis,a distant relationship with other species.
基金This study was funded by the Walton Family Foundation(101951)the Fondo Mexicano para la Conservaci´on de la Naturaleza(M1906002).
文摘Clams of the family Veneridae in northwest Mexico have traditionally been exploited by small-scale fisheries.Despite their socioeconomic importance for coastal communities in the region,most catch zones are currently in decline due to a lack of harvest control regulations that would impede the depletion of local fishing banks.In Puerto Libertad,in the northern reaches of the Gulf of California,banks of commercially unexploited clam species,including Megapitaria aurantiaca,M.squalida and Dosinia ponderosa,were discovered.The adequate management and exploitation of these banks requires developing basic knowledge regarding the abundance of the species and establishing reference points to determine clear,simple harvest regulations.The goal of this study was to identify population abundance in these banks and ascertain the parameters of the life history of the species found there in order to propose a harvest strategy that will allow the sustainable exploitation of this resource.A total of 288 transects were conducted in the two clam banks to identify species density.Abundance was determined using a geostatistical method.The relative cohort biomass-at-length was estimated to evaluate the effect of different lengths of first capture on the remaining biomass.Based on these data,two harvest control regulations were proposed:a maximum catch(Cmax)of 10%of the total estimated biomass,and a minimum optimal catch size(Lc).The abundance estimates were M.squalida(266,293-381,881 individuals);D.ponderosa(2,779,100-3,455,597);and M.aurantiaca(408,783-447,391).The harvest control regulations proposed are:M.squalida,Cmax=2.98 t and Lc=50.33 mm;D.ponderosa,Cmax=49.67 t and Lc=103.44 mm;and M.aurantiaca,Cmax=15.87 t and Lc=80.85 mm.These results are important as reference information for implementing harvest strategies in clam-fishing banks,and as a contribution to the management and sustainable exploitation of fisheries in the region.
