Benthic Macrofauna Communities In Intertidal Zone In Daya Bay And Kaozhouyang Bay

A gradually increasing influence of human activities has occurred in Daya Bay and Kaozhouyang Bay in the coastal areas of Guangdong province in recent decades.In order to understand the spatial and temporal disparities of macrofauna community under the disturbance of human activities from four intertidal habitates,namely sandy beach,mangrove,mudflat and rock stone,14 sections on macrofauna investigation were carried out in Daya Bay and Kaozhouyang Bay among different habitats,different sections and different seasons in 2018 and 2019.With the analysis of macrofauna community parameters including species,abundance,biomass,Shannon-Wiener diversity Index(H '),evenness Index(J),richness Index(d),AZTI's Marine Biotic Index(AMBI)and multivariate-AMBI(M-AMBI),etc.,the effect degree of human activities on macrofauna communities were probed in the intertidal zone of Daya Bay and Kaozhouyang Bay.The research results may provide scientific basis for the protection,rational development and ecological restoration of the intertidal zone in Daya Bay and Kaozhouyang Bay.The main research results were as follows:(1)A total of 43 species of macrofauna were collected from 5 intertidal sandy beach sections in Daya Bay during 2 trips which took place in January 2018 and July 2018,including 16 species of polychaetes,1 species of oligochaetes,2 species of gastropods,11 species of bivalves,12 species of crustaceans and 1 species of insecta.Differences in macrofauna dominant taxa and dominant species were observed among 5 intertidal sandy beach sections in Daya Bay,showing richer species and higher abundance of polychaetes in the west of Daya Bay then followed in the middle of the bay(top of the bay),and lower species and abundance of polychaetes in the east of the bay.Meanwhile,the abundace of gastropods was opposite,that is,the abundance of gastropods was lower in the west of Daya Bay,then the abundance of gastropods in the middle Daya Bay took second place,and higher abundance were detected in the east of the bay.Cluster and MDS analysis of macrofauna communities both confirmed the results noted above.Because of the thermal discharge and drainage caused by the nuclear power plant,Acetes chinensis which is planktonic has appeared in the west of Daya Bay with a high abundance.(2)A total of 170 species of macrofauna were collected from mangrove and mudflat intertidal zone in Daya Bay and Kaozhouyang Bay during four quarters in 2018 and 2019,including 50 species of bivalve,50 species of crustaceans,48 species of polychaetes,8 species of gastropods,3 species of insectas,3 species of fish,2 species of nemertea,and 1 species each from echinoderms,sipuncula,oligochaeta,cnidaria,platyhelminthes and polyplacophora.Macrofauna communities in MA1 and MA2 sections of mangrove habitat suffered from several human activities.Compared with historical data,the dominant species and biodiversity in this habitat changed significantly,and the dominant taxa became polychaetes instead of gastropods,meanwhile the species diversity of the communities decreased.(3)A total of 94 species of macrofauna were collected from rock stone in Daya Bay during 2 trips which took place in January 2018 and July 2018,including 19 species of polychaetes,26 species of gastropods,18 species of bivalves,18 species of crustaceans and 13 species of other taxa.More species and higher diversity index of macrofauna were found in R2 section from the middle of Daya Bay(top of the bay),while fewer species and lower diversity index of macrofauna showed in R1 and R3 sections at the mouth of the bay.Owing to more residents at the top of the bay,then more sewage discharge and more nutrient abundance,plenty of food was supplied here to feed the macrofauna.(4)With the comparison of macrofauna communities in four intertidal habitats,the results revealed that the distribution pattern of macrofauna species was as follows:mangrove and mudflat habitats(170 species)>rock stone habitat(94 species)>sandy beach habitat(43 species).The density distribution pattern of macrofauna was as follows:mangrove and mudflat habitats(1085.3 ind./m2)>rock stone habitat(925.8 ind./m2)>sandy beach habitat(500.1 ind./m2).The biomass distribution pattern of macrofauna was as follows:rock stone habitat(821.5799 g/m2)>mangrove and mudflat habitats(190.0928 g/m2)>sandy beach habitat(19.1886 g/m2).Results show that both Shannon Wiener and Marglef index were both as follow:mangrove and mudflat habitats(H'=2.03,d=1.77)>rock stone habitat(H'=1.90,d=1.72)>sandy beach habitat(H'=1.07,d=0.60).The evenness index distribution pattern of macrofauna was as follows:sandy beach habitat(J=0.73)>mangrove and mudflat habitats(J=0.60)>rock stone habitat(J=0.59).The effective number of species index distribution pattern of macrofauna was as follows:rock stone habitat(ENS=4.74)>mangrove and mudflat habitats(ENS=4.24)>sandy beach habitat(ENS=2.38).The AMBI index distribution pattern of macrofauna was as follows:mangrove and mudflat habitats(AMBI=1.00)>sandy beach habitat(AMBI=0.59).The M-AMBI index distribution pattern of macrofauna was as follows:sandy beach habitat(MAMBI=0.80)>mangrove and mudflat habitats(M-AMBI=0.60).It was obvious that macrobenthic communities from different habitats in the intertidal zone of Daya Bay and Kaozhouyang Bay were significantly different due to their different substrates.