Effects Of Shrimp Farming Effluent And Latitude On Functional Traits Of Mangrove Forests

Mangrove forests,grow in the coastal intertidal zone in tropical and subtropical regions of the world’s coastlines at low latitude,but are threatened by agriculture,aquaculture,overexploitation,tourism,and urbanization,and aquaculture practices that are responsible for the bulk of the increasing losses of mangrove forests worldwide.Shrimp farming is the main part of aquaculture and developed rapidly in the tropics and subtropics of Asia and South America in the 1980s and 1990s,and shrimp farming release nutrient waste to surroundings has caused broad-scale shifts in mangrove ecosystem worldwide,including the changes in habitats and functional traits of mangroves,even to the widespread destruction of mangroves in many countries.In order to make a sustainable development relationship between shrimp farming and mangroves forest,the cooperation research between shrimp farming and mangroves is urgently needed as the basis for formulating effective regulatory measures.In addition,few studies have been conducted on plant functional traits and biogeographic analysis in mangrove ecosystem,multi-dimensional studies are needed for the comprehensive evaluation.In this study,the functional traits of Aegiceras corniculatum in different shrimp farming effluent discharged areas as well as the latitude diversity of mangrove plant community structure gradient were studied,the results showed that:(1)The shrimp farming effluent discharged has a significant influence on the morphological,biomass allocation patterns and elemental contents of A.corniculatum seedlings,and the response of functional traits in below-ground organs was obviously to the effluent than those in above-ground organs.(2)In the habitats influenced by shrimp farming effluent,the relationship between leaf vein density and stomatal density in adult leaves of A.corniculatum have an obvious changed,accompany the correlation weakened significantly in salt gland density and stomatal functional traits.(3)The effects of shrimp farming effluent discharge on the contents of nitrogen and phosphorus in the propagules,seedlings and leaves of A.corniculatum were higher than those in unaffected habitats.It proved that A.corniculatum possessing an important role in element migration,transformation and enrichment in eutrophication habitats;(4)The effects of shrimp farming effluent on the elements are more significant than those of morphological and biomass.The plasticity of these functional traits and the degree of influence have positive synergistic effects.(5)The discharged of shrimp farming effluent changed the ecological stoichiometric characteristics in the organs of A.corniculatum seedlings,and the C,N and P of each organ were re-matched,indicating that the ecological stoichiometry internal stability of the shrimp pond culture wastewater discharge area has been disturbed,and the disturbance cannot be self-recovery in a short time.(6)With the increase of latitude,the mangrove community changes along the trend of developmental,mature and stable→growth→declining.Species richness index(S)has obvious latitude gradient,while shannon-wiener index(H’),Simpson index(D)and Pielou’s index(J)did not show an Significant latitude gradient,but it present a strong correlation and a relatively consistent change trend between them.