Abstract:In this study, Landsat data for 1989, 1994, 2004, and 2014 were used to evaluate the process of land reclamation in the Nansha wetland area, using methods including remote sensing imagery interpretation, geographic information system (GIS) digital methods, and spatial overlay analysis. The data obtained from two in situ surveys during the periods 2002-2003 and 2013-2014 were also used to compare the changes in the biological resources of organisms. The results were as follows: (1) The lengths of the coastline during the four periods of 1989, 1994, 2004, and 2014 were 213.6 km, 230.0 km, 232.5 km, and 248.6 km, respectively, with increase rates of 3.28 km/a, 0.25 km/a, and 1.61 km/a during 1989-1994, 1994-2004, and 2004-2014, respectively; the maximum distance of the seaward extension from the coastline during these three periods were about 4900 m, 1700 m, and 7700 m, respectively. (2) The total increase in land area was 46.3 km2 in 1989-2014; the proportional increases in area relative to the total increase were 40.6% in 1989-1994, 24.41% in 1994-2004, and 34.99% in 2004-2014; reclamation activities were more frequent on Wanqingsha Island and Longxue Island than those at other sites in the Nansha wetland. (3) The numbers of zooplankton, macrozoobenthos, intertidal organisms, fish, and cephalopods decreased by 60.34%, 73.21%, 26.67%, 79.78%, and 50.00%, respectively. Their densities decreased by 58.49%, 12.38%, 79.96%, 78.78%, and 66.79%, respectively. Their biomasses decreased by 82.16%, 73.23%, 15.83%, 70.49%, and 62.43%, respectively. The numbers and densities of shellfish decreased by 13.33% and 69.85%, respectively, whereas their biomass increased by 114.20%. (4) The Shannon-Wiener diversity index for zooplankton increased by 10.24%, whereas the indices for the macrozoobenthos, intertidal organisms, fish, shellfish, and cephalopods decreased by 71.10%, 91.82%, 18.18%, 66.90%, and 73.68%, respectively. The dominant species changed markedly between 2002-2003 and 2013-2014. Land reclamation of Nansha wetland not only changes the type and length of costline, occupuies valuable wetland resource, but also leads passive effect on the around marine animals.
