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The ecological environment of karst forests is highly fragile compared to other forest types.Seed dispersal is extremely important for karst forest,assisting in maintaining plant biodiversity,resulting in lower anti-interference ability and forest resilience.Langurs are believed to be significant dispersers of seed within some forests.The langurs′ diet consists mainly of leaves;however,fruits are an important supplement.Through their fruit feeding behavior,langurs that inhabit limestone forests are suspected to facilitate seed dispersal.This potentially means that they play a role in maintaining karst forest biodiversity.We investigated fruit selectivity and seed dispersal behavior of the Hatinh langur(Trachypithecus francoisi hatinhensis) in Phong Nha-Ke Bang National Park,Vietnam.Our study was undertaken from July 2009 to December 2010,where we used instantaneous scan sampling and direct observation.The Hatinh langurs were observed consuming fruit from 131 plant species.These species belonged to 38 different plant families.Hatinh langurs fed on a greater number of fruit-bearing plant species and for a longer peak duration compared to Franois′ langur living in other areas.This is because the abundance of numerous fruit resources in the rainforest of the National Park.The results of our analysis reflected the behavior of Hatinh langurs,which showed a relatively low selective preference of fruit species(-0.3S112 of fruit species 0.3).In addition,food resource availability of different fruit species did not significantly affect langur feeding intensity(r=-0.13,P= 0.150.05).However,we found that the number of fruit species and langur feeding intensity was greater in monsoon season compared with the dry season(z=-2.903,P=0.020.05).Hatinh langurs demonstrated preference feeding on berries and drupes(106 species of two fruit kinds,80.9% of fruit diet),as both are easily handled because of the large pericarp.These fruit are relatively large(104 species 5g of fruit weight,79.3% of fruit diet).Although fruit color varied,three colors were preferred by the langurs;yellow(46 species),red(30 species) and green(14 species) from a total of 90 fruits(68.7% of fruit diet).Hatinh langurs were able to swallow seeds(3cm) from 85 plant species and disperse seed up to 397m.They favored fleshly fruits such as Ficus benjamina,Vatica diospyroides,Broussonetia papyrifera,Allospondias lakonensis,Syzygium samarangense and Ficus hispida.This langur may play an important dispersal role in plant species with large thick-husked fruits,such as Syzygium jambos,Nephelium lappaceum and Baccaurea ramiflora.This is because frugivorous birds are unable to swallow the seed of such fruits.The feeding period of the langur on fruits sustains them for six months of the year.During the rainy season(August to December),the feeding intensity by the langur on fruit peaked,with monthly fecal seed counts being 1000.Our results suggest that the Hatinh langur plays a key role as a seed disperser enhancing the dispersal of large fruit plants.The correlation between monkeys and fruit plants may mean that the Hatinh langur has an important role maintaining the biodiversity in karst forests.

Sediment quality triad(SQT),one of the important sediment quality assessment approaches,is defined as a conceptual and integrated technique based on biological response.It mainly comprises three complementary levels of evidence including sediment chemistry,laboratory sediment toxicity test and in situ benthic community structure.Each of the three traditional levels of evidence alone can independently reflect the environment risk of the contaminant in sediment by selecting suitable parameters.However,by combining these three levels of evidence,this approach can provide a comprehensive assessment in a weight of evidence means,which enhances the causal-effect relationship between the elevated chemical exposure and adverse biological effect,furthers the understanding of the ecology relevance between the hazardous materials and pollution levels.As consequences,it provides a robust basis for costal environmental control and remediation.Our objective is to focus on the newly advancement of SQT approach,draw experience and lessons to promote the coastal sediment quality assessment in China.This paper reviewed the history and development of the method detailed in 2 aspects including evidence composition,data simplification and interpretation method.We further investigated techniques to enhance the reliability of SQT evaluation and prospect for the method and application research in view of our country′s current status of coastal sediment quality assessment.Literature analysis shows that diversifying levels of evidence and improving data interpretation method can make evaluation result more reliable and understandable.SQT assessment can be more transparency by formalize and standardize the current interpretive tools,for instance,the tabular decision matrices.The SQT has been intensively used in the North America and frequently adopted as environmental management tools in European countries especially the Spain.It is one of the most applicable comprehensive assessment methods that the SQT intends to evaluate the adverse effect caused by chemical stressor in mediums like sediment.However,it should further develop to resolve and enhance the reliability,transparency of evaluation.

The increasing input of nutrients to lakes and estuaries by the anthropogenic activities has resulted in the aquatic eco-environment changes,such as the change of food chain,eutrophication and frequently seasonal hypoxia in bottom waters,which can be recorded in sediments.The biogenic elements and their stable isotopes in sediments are effective proxies to reflect the paleoproductivity and nutrient level in waters.The indicative significance of biogenic elements(C,N,P,Si) to the change of primary production,material sources and nutrient levels was reviewed in this paper.TOC,TN,δ13C,CaCO3 and BSi in sediments reflecting the content of organic matter and the growth of phytoplankton,can be used as effective proxies to indicate the primary production level.Source identification of organic matter by the differences of δ13C,δ15N and C/N values between different types of plants has important value to study the influence of anthropogenic activities on the aquatic environment and eutrophication.The increasing trend of TN,δ15N,TP and non-apatite phosphorus(NAIP) in sediments reflects the increasing input of terrestrial nitrogen and phosphorus to coastal waters.BSi can reflect the phytoplankton growth,and further indicate the Si concentration variations and eutrophication in waters.Biogenic elements are influenced by many factors in their deposition and burial,such as diagenesis and hydrodynamic conditions,which can disturb the sedimentary records of biogenic elements and then hinder the proper indication of environmental changes by these proxies.Consequently,in order to exactly understand the aquatic environmental changes,it is essential to comprehensively analyze the information of environmental changes provided by multiple biogenic element proxies and to fully consider the potential interference factors for the paleoenvironmental reconstructions.