Research And Analysis On The Lancelet In Fangji Island Sea Areas Of Maoming

This paper describes the species of lancelet and general distribution of it, introduces the lately study of lancelet both at home and abroad and analyses its academic position. Based on it, for the first time an all-embracing research on lancelet has been carried out in Fangji Island of Maoming between 2003 and 2004, hence a large quantity of lancelet, about 200 km~2, was initially discovered. Now it exists 3300 tons, up to 105 ind per square metre on average.This paper describes and analyses the morphological characters and some biological behaviours of lancelet from Maoming: The species was identified as Branchiostoma belcheri Gray, and for the main exterior morphological characters, the Branchiostoma belcheri Gray from Maoming has no differences distinctly to that from Xiamen or Beibu Gulf, expect the larger body size; the food remnant in alimentary canal of lancelets from Maoming is mud-sand and oddment mainly, and 53 specieses of Life-form component were identified. These specieses consist of bottom diatoms mostly, some dinoflagellates and bottom copepodas etc. Mature individuals appeared in each survey month in the whole year, but the spring (May) is the mainly spawning season. The distribution of different size individuals varies with bottom quality and water depth.The quality of sea water is an important ingredient affecting lancelet, therefore it is necessary to sample the sea water there and do some analysis. By the research work of Monitoring Center of Fishery Resources and Environment, it turns out that the water quality is fairly good. Except for some oil pollutant, for the content of Pb exeeding the standard of first class water quality, for the content of Hg close to the...