Seagrass and mangrove habitats have long been established as critical for diverse species at various life-stages,particularly as nursery grounds.However,despite their intrinsic and environmental value,these ecosystems...Seagrass and mangrove habitats have long been established as critical for diverse species at various life-stages,particularly as nursery grounds.However,despite their intrinsic and environmental value,these ecosystems are increasingly threatened by anthropogenic activities.In Bimini,Bahamas,where ongoing development threatens ecosystem integrity,baited remote underwater video surveys(BRUVs)were used to examine faunal communities in both nearshore habitat and a shallow water central lagoon(average depth 1 m).The study assessed species abundances and spatial distribution in a currently unperturbed of the North Bimini Marine Reserve(NBMR).A total of 140 BRUVs,conducted over a 13-month period,recorded 62 species from 27 different families.MaxN was used to assess relative abundances and multivariate analyses(i.e.nMDS,PCA,PERMANOVA)investigated differences in community composition across discrete factors and environmental variables.Boosted Regression Trees(BRTs)were used to explore environmental variables for their uncorrelated influences on recorded species diversity.Findings evidenced the importance of habitat diversity and particularly mangroveadjacent habitat for teleost fishes in Bimini with species diversity and abundance being significantly greater in the mangrove-adjacentdge habitat.Further,the study highlighted differences in environmental conditions between habitat types and the association this had with species diversity,abundance and distribution.Despite the shallow water environment,BRUVs served as a scalable,non-invasive technique to assess community structures within the study site.Results from this study should inform ongoing decision-making processes regarding the protection of the Bimini Islands ecosystem.展开更多
Using outward rotations, we obtain an approximation algorithm for MAXn/2-UNCUT problem, i.e., partitioning the vertices of a weighted graph into two blocks of equalcardinality such that the total weight of edges that ...Using outward rotations, we obtain an approximation algorithm for MAXn/2-UNCUT problem, i.e., partitioning the vertices of a weighted graph into two blocks of equalcardinality such that the total weight of edges that do not cross the cut is maximized. In manyinteresting cases, the algorithm performs better than the algorithms of Ye and of Halperin andZwick. The main tool used to obtain this result is semidefinite programming.展开更多
基金This study was supported by a Keystone Grant to BBFSF from the Save Our Seas Foundation.
文摘Seagrass and mangrove habitats have long been established as critical for diverse species at various life-stages,particularly as nursery grounds.However,despite their intrinsic and environmental value,these ecosystems are increasingly threatened by anthropogenic activities.In Bimini,Bahamas,where ongoing development threatens ecosystem integrity,baited remote underwater video surveys(BRUVs)were used to examine faunal communities in both nearshore habitat and a shallow water central lagoon(average depth 1 m).The study assessed species abundances and spatial distribution in a currently unperturbed of the North Bimini Marine Reserve(NBMR).A total of 140 BRUVs,conducted over a 13-month period,recorded 62 species from 27 different families.MaxN was used to assess relative abundances and multivariate analyses(i.e.nMDS,PCA,PERMANOVA)investigated differences in community composition across discrete factors and environmental variables.Boosted Regression Trees(BRTs)were used to explore environmental variables for their uncorrelated influences on recorded species diversity.Findings evidenced the importance of habitat diversity and particularly mangroveadjacent habitat for teleost fishes in Bimini with species diversity and abundance being significantly greater in the mangrove-adjacentdge habitat.Further,the study highlighted differences in environmental conditions between habitat types and the association this had with species diversity,abundance and distribution.Despite the shallow water environment,BRUVs served as a scalable,non-invasive technique to assess community structures within the study site.Results from this study should inform ongoing decision-making processes regarding the protection of the Bimini Islands ecosystem.
基金This research is partly supported by Chinese NSF grant 19731001 and National 973 Information Technol- ogy High-Performance Software Program of China with grant No. G1998030401The author gratefully acknowledges the support of K. C. Wong Education
文摘Using outward rotations, we obtain an approximation algorithm for MAXn/2-UNCUT problem, i.e., partitioning the vertices of a weighted graph into two blocks of equalcardinality such that the total weight of edges that do not cross the cut is maximized. In manyinteresting cases, the algorithm performs better than the algorithms of Ye and of Halperin andZwick. The main tool used to obtain this result is semidefinite programming.
