Abstract

This study assessed zooplankton density and Chl-a amount to understand their spatial and seasonal variation in Lake Malombe. Samples were collected for analysis during the hot, dry season (HDS) and cool, dry, windy season (CDWS). The zooplankton identified were Tropodiaptomus cunningtoni (TC), Mesocyclops aequatorialis aequatorialis (MAA), Thermocyclops neglectus (TN), Bosmina longirostris (BL), Diaphanosoma spp. (DS), and Nauplii. These zooplankton groups belong to copepods, Cyclopidae, Cladocera, Ctenopod, and Rotifers. Chl-a exhibited a substantial seasonal variation, with the highest concentration observed in HDS and lowest in CDWS. Zooplankton such as T. cunningtoni, M. aeq. aequatorialis, T. neglectus, B. longirostris, Diaphanosoma spp, Nauplii, and Rotifer increased during the HDS. The water temperatures (WT), pH, Dissolved Oxygen (DO), and Chl-a positively correlated with all zooplankton densities. Sodium (Na⁺) and Potassium (K⁺) ions positively correlated with TC, MAA, DS, Nauplii, and Rotifers. Chloride ion (Cl^-) positively correlated with DS, Rotifers, while Carbonate ion (CO₃^2-) positively correlated with TC. Bicarbonate (HCO₃^-) correlated positively with DS and Rotifers, while TDS correlated negatively with BL, Nauplii, and Rotifers. Nitrite affected zooplankton density negatively, while SRP had a positive effect. The study revealed that physical-chemical variables, some significant ions, and Chl-a are the most critical factors influencing the spatial and seasonal variation of zooplankton density in the lake. These findings demonstrate the interaction between physical-chemical variables, Chl-a, and zooplankton and highlight the significance of ecological understanding of the complex dynamics of the food web system in shallow tropical lakes such as Lake Malombe- under the changing climate.

摘要

本研究评估了浮游动物密度和 Chl-a 量，以了解它们在马隆贝湖中的空间和季节变化。在炎热干燥季节 (HDS) 和凉爽干燥多风季节 (CDWS) 收集样品用于分析。确定的浮游动物是Tropodiaptomus cunningtoni (TC)、Mesocyclops aequatorialis aequatorialis (MAA)、Thermocyclops ignoreus (TN)、Bosmina longirostris (BL)、 Diaphanosoma spp。(DS) 和无节幼体。这些浮游动物群属于桡足类、Cyclopidae、枝角类、栉足类和轮虫类。Chl-a 表现出显着的季节性变化，在 HDS 中观察到的浓度最高，在 CDWS 中观察到的浓度最低。浮游动物如T. cunningtoni, M. aeq. aequatorialis, T. ignoreus, B. longirostris,Diaphanosoma spp、无节幼体和轮虫在 HDS 期间增加。水温 (WT)、pH、溶解氧 (DO) 和 Chl-a 与所有浮游动物密度呈正相关。钠 (Na ⁺ ) 和钾 (K ⁺ ) 离子与 TC、MAA、DS、无节幼体和轮虫正相关。氯离子(Cl ^- )与DS、轮虫正相关，而碳酸盐离子(CO ₃ ^2- )与TC正相关。碳酸氢盐 (HCO ₃ ^-) 与 DS 和轮虫正相关，而 TDS 与 BL、无节幼体和轮虫负相关。亚硝酸盐对浮游动物密度有负面影响，而 SRP 有正面影响。研究表明，理化变量、一些重要离子和 Chl-a 是影响湖泊浮游动物密度空间和季节变化的最关键因素。这些发现证明了物理化学变量、Chl-a 和浮游动物之间的相互作用，并突出了生态理解在气候变化下的热带浅湖（如马隆贝湖）复杂动态的重要性。