4种拟除虫菊酯类农药对海带生长及叶绿素a含量的影响

为研究不同拟除虫菊酯类农药对海带(Laminaria japonica)生长和叶绿素a(Chl a)含量的影响,选取溴氰菊酯、联苯菊酯、氰戊菊酯、醚菊酯等4种拟除虫菊酯类农药,设置1、5、10、50、100、500μg/dm³ 6个梯度对海带进行半静置染毒。结果表明：低浓度(1μg/dm³)组4种拟除虫菊酯类农药对海带生长均具有促进作用(P<0.05),高浓度(100、500μg/dm³)对海带生长具有显著抑制作用(P<0.01)。溴氰菊酯、联苯菊酯、氰戊菊酯、醚菊酯对海带的24 d半抑制效应浓度(EC₅₀)分别为82.4、53.0、10.7、14.6μg/dm³,抑制作用大小为氰戊菊酯≈醚菊酯>联苯菊酯>溴氰菊酯。低浓度(1、5μg/dm³)组海带体内Chl a含量均出现升高,具有一定促进作用(P<0.05);高浓度(100、500μg/dm³)组海带体内Chl a含量均出现明显下降,具有显著抑制作用(...     

The distribution of phytoplankton size and major influencing factors in the surface waters near the northern end of the Antarctic Peninsula

The waters near the Antarctic Peninsula have always been a study hot spot because of their variable and unique oceanographic conditions.To determine the distribution and possible influencing factors on phytoplankton size and abundance near the Antarctic Peninsula,a large-scale survey was conducted during the austral summer of2018.Samples were collected in 27 stations located in the Drake Passage(DP),South Shetland Islands(SSI),and South Orkney Islands(SOI).Phytoplankton communities were described using chlorophyll a(Chl a),flow cytometry and light microscopy to cover a size range from pico-to microphytoplankton.Nanophytoplankton,especially small nanophytoplankton(2-6 μm) with abundance ranging from 0.66 ×10~3 cells/mL to 8.46 ×10~3 cells/mL,was predominant throughout the study area.Among different regions,there was an obvious size shift.The proportion of picophytoplankton near the Elephant Island(EI) and DP was higher than other regions,and larger cells were found mainly in east of SOI.The distribution of phytoplankton abundance detected by flow cytometry was not completely consistent with Chl a concentrations due to the contribution of larger cells to Chl a.Possible influencing factors on the phytoplankton size distribution were discussed.The properties of water masses such as temperature and salinity can influence the phytoplankton size distribution.Correlation analysis revealed that only picophytoplankton is significantly correlated with salinity.Light and Fe availability might affect phytoplankton abundance and size distribution especially near the waters of SSI and EI in this study.It was also speculated that the abundance of cryptophytes is possibly related to ice melting.     

南海北部秋季营养盐、溶解氧、pH值和叶绿素a分布特征及相互关系

通过2004年9月至10月对南海北部水域的现场调查,分析了表层海水中溶解氧、叶绿素a、pH值和营养盐等水质因子的空间分布分布特征,并讨论了它们之间的相互关系。结果表明:在南海北部海区的表层海水中,各水质因子在空间分布上大多呈现块状分布,且东西两侧的海水有较为明显的差异;海水中的溶解氧、pH值均表现出与海水温度相反的分布趋势;海水中的叶绿素a(Chla)和众多的水质因子表现出多元相关性,说明水体中浮游植物的生长繁殖是众多水质因子在南海北部综合作用的结果,而Chla和水体中亚硝酸盐的高相关性,说明南海北部水体中浮游植物的生长和亚硝酸盐有着比其他营养盐因子更为密切的联系。