两种海洋赤潮微藻赤潮异弯藻和米氏凯伦藻之间的相互作用

在实验生态条件下研究了不同起始生物量比的两种海洋赤潮微藻赤潮异弯藻(Heterosigma akashiwo)和米氏凯伦藻(Karenia mikimotoi)的种群增长特征。结果发现: 1)在单培养体系中, H. akashiwo和K. mikimotoi的种群增长均可用逻辑斯谛增长模型(Logistic equation)拟合, 但不同的起始密度比对两种微藻的生长可产生显著影响: 随着起始密度的增加, 种群的瞬时增长率(r)随之增加, 但环境负载能力(K)逐渐降低, 进入指数增长期和静止期的时间也相应缩短。2)在共培养体系中, 两种微藻的K值都受到明显的抑制, 与对照组(单培养体系)相比差异显著(p＜0.05); 不同起始生物量比对共培养体系中两种微藻的生长和竞争影响显著: 当H. akashiwo和K. mikimotoi的起始生物量比(H:K)为1:4和1:16时, K. mikimotoi在竞争中占据优势地位; 当H:K=1:1时, H. akashiwo在竞争中占绝对优势。他感作用是导致本实验结果的可能原因。

INTERACTIONS BETWEEN TWO SPECIES OF MARINE BLOOM MICROALGAE UNDER CONTROLLED LABORATORY CONDITIONS: HETEROSIGMA AKASHIWO AND KARENIA MIKIMOTOI

Aims Harmful algal blooms caused by multiple toxic or harmful algal species have globally expanded and threaten marine sustainability, and interaction among bloom species is thought to play an important role in bloom development and elimination. Our objective is to study the interactions of two causative bloom-forming species of coastal China, Heterosigma akashiwo and Karenia mikimotoi, under con-trolled laboratory conditions. Methods The experiments were carried out in mono- and co-culture. Results were analyzed with the software package Sigmaplot 8.0 and SPSS 13.0, and ANOVA and Duncan’s multiple range tests were used for data analysis. Important findings Growth of both species at different initial cell densities in mono-culture was well predicted by a logistic model. Their environmental capacity (K) decreased steadily while the intrinsic rate of increase (r) increased with the initial cell density increment, and the time for entering exponen-tial and stationary growth phases shortened simultaneously. Both K values of the microalgae in co-culture were inhibited as compared to mono-culture (p＜0.05), and their competition changed simul-taneously with the ratio of their initial biomass. Under co-culture, K. mikimotoi became dominant when the initial biomass ratio of H. akashiwo (H): K. mikimotoi (K) was set at 1:4 and 1:16; however, H. akashiwo overcame K. mikimotoi when the ratio turned to H:K = 1:1. Therefore, initial biomass played an important role in microalgal inter-specific competition in co-culture. Allelopathy is a possible reason for the observed results.