大规模增养殖区柘林湾叶绿素a的时空分布

柘林湾是粤东一个大规模海水增养殖区和赤潮重灾区.2001年7月至2002年7月对柘林湾及其周边水域(共设19个站位)进行的叶绿素a含量周年调查结果表明,调查海区叶绿素a站位实测值年变化为0.01~3.26 mg/m3,均值为0.56 mg/m3.平面分布的基本格局表现为湾顶黄冈河内与湾口外侧海域的叶绿素a含量明显高于湾内的,湾内外侧和东部水域的叶绿素a含量明显高于湾内内侧和湾西部的.结合同步调查的水化数据得知,柘林湾是一个高营养盐、低叶绿素的海湾,其原因可能与高密度、大规模海水增养殖业引起的水流不畅、水下光照减弱和养殖贝类的摄食等有关.柘林湾叶绿素a含量的季节变化显著,最高值出现在2001年夏季8月,最低值出现在冬季1月和2002年7月,其中2002年7月的叶绿素a含量仅为2001年7月的1/10左右.这种巨大的年际间变化显然与2001~2002年厄尔尼诺现象导致粤东地区于2002年春夏期间气候异常、干旱少雨、径流剧减和调查海区浊度大幅升高有关.

Spatial-temporal distribution of chlorophyll a in the Zhelin--Bay A large-scale maricultural area

Chlorophylla around the Zhelin Bay-a large-scale maricult ure(with 19 sampling stations),eastern Guangdong,where the harmful algal blooms most frequently occurred,was investigated from July 2001 to July 2002.The results showed that concentrations of chl.a in the sampling stations range from 0.01 to 3.26 mg/m³,with an annual average of 0.56 mg/m³.The concentration of chl.a in the investigated area was higher in the Huanggang River and the out side of the bay than that in the inside,consequently resulted in that chl.a was greater in the outer and eastern bay than those in the inner and western bay. Based on the data from the related investigations,the Zhelin Bay is a bay with high nutrients and low chlo-rophylla.Such pattern might be mainly due to the low water exchange,low illumination and feeding of seashells caused by large-scale mariculture.There was a significant seasonal variation in chl.a during the investigation.The highest was found in August 2001,and the lowest in January and July 2002.The concentration of chl.a in July 2002 was equal to only 10% of that in July 2002.Such large difference occurred between consequent years might be related to 2001~2002 El Niño event,which resulted in low precipitation around the eastern Guangdong and the consequent largely decrease of PO₄-P and increase of total suspension materials in July 2002 in the Zhelin Bay compared with those in July 2001.