Shaari Asma Liyana, Surif Misni, Latiff Faazaz Abd, Omar Wan Maznah Wan, Ahmad Mohd Noor
School of Distance Education, Universiti Sains Malaysia, 11800 USM Pulau Pinang, Malaysia.
Fisheries Research Institute, Jalan Batu Maung, 11960 Batu Maung, Pulau Pinang, Malaysia.
Trop Life Sci Res. 2011 May;22(1):51-69.
Many reports have revealed that the abundance of microalgae in shrimp ponds vary with changes in environmental factors such as light, temperature, pH, salinity and nutrient level throughout a shrimp culture period. In this study, shrimp cultivation period was divided into three stages (initial = week 0-5, mid = week 6-10 and final = week 11-15). Physical and chemical parameters throughout the cultivation period were studied and species composition of microalgae was monitored. Physical parameters were found to fluctuate widely with light intensity ranging between 182.23-1278 μmol photon m(-2)s(-1), temperature between 29.56°C -31.59°C, dissolved oxygen (DO) between 4.56-8.21 mg/l, pH between 7.65-8.49 and salinity between 20‰-30‰. Ammonium (NH4 (+)-N), nitrite (NO2 (-)-N), nitrate (NO3 (-)-N), and orthophosphate (PO4 (3-)-P) concentrations in the pond at all cultivation stages ranged from 0.017 to 0.38 mg/l, 0.24 to 2.12 mg/l, 0.06 to 0.98 mg/l and 0.16 to 1.93 mg/l respectively. Statistical test (ANOVA) showed that there were no significant difference (p<0.05) in nutrients concentrations among the cultivation stages. All nutrients concentrations however were still in the tolerable level and safe for shrimp culture. The chlorophyll a contents were found to range from 5.03±2.17 to 32.61±0.35 μg/l throughout the cultivation period. A total of 19 microalgae species were found in the shrimp pond, with diatoms contributing up to 72% of the species followed by Chlorophyta (11%) and Cyanophyta (11%). However, weekly species abundance varied through the study period. At the initial stage, when there were no shrimps in the pond, Anabaena spp. and Oscillatoria spp. (Cyanophyta) were the dominant species, followed by Chlorella sp. and Dunaliella sp. (Chlorophyta). When shrimps were introduced into the pond, Amphora sp., Navicula sp. Gyrosigma sp. and Nitzschia sp. (diatoms) started to exist. At the middle and towards the final stage of the shrimp culture period diatoms were the dominant species. The Chlorophyta (Chlorella sp.) domination took place only twice, which was at week 2 and 13. The absence of some of the coastal water microalgae species in the shrimp pond was most likely due to the fact that they could not tolerate the physicochemical factors of harsh environment. In this study, Cylindrotheca closterium was regarded as the most tolerant species among the microalgae due to its ability to exist for 6 weeks out of the 15 weeks of cultivation.
许多报告显示，在整个对虾养殖期间，虾塘中微藻的丰度会随着光照、温度、pH值、盐度和营养水平等环境因素的变化而变化。在本研究中，对虾养殖期分为三个阶段（初期=第0 - 5周，中期=第6 - 10周，末期=第11 - 15周）。研究了整个养殖期的理化参数，并监测了微藻的种类组成。发现物理参数波动很大，光照强度在182.23 - 1278 μmol光子m(-2)s(-1)之间，温度在29.56°C - 31.59°C之间，溶解氧（DO）在4.56 - 8.21 mg/l之间，pH值在7.65 - 8.49之间，盐度在20‰ - 30‰之间。在所有养殖阶段，池塘中铵（NH4(+)-N）、亚硝酸盐（NO2(-)-N）、硝酸盐（NO3(-)-N）和正磷酸盐（PO4(3-)-P）的浓度分别为0.017至0.38 mg/l、0.24至2.12 mg/l、0.06至0.98 mg/l和0.16至1.93 mg/l。统计检验（方差分析）表明，各养殖阶段的营养物质浓度没有显著差异（p<0.05）。然而，所有营养物质浓度仍处于可耐受水平，对虾养殖是安全的。发现整个养殖期叶绿素a含量在5.03±2.17至32.61±0.35 μg/l之间。在虾塘中共发现19种微藻，其中硅藻占物种总数的72%，其次是绿藻门（11%）和蓝藻门（11%）。然而，在整个研究期间，每周的物种丰度有所不同。在初期，池塘中没有对虾时，鱼腥藻属和颤藻属（蓝藻门）是优势种，其次是小球藻属和杜氏藻属（绿藻门）。当对虾放入池塘后，双眉藻属、舟形藻属、布纹藻属和菱形藻属（硅藻）开始出现。在对虾养殖期的中期和末期，硅藻是优势种。绿藻门（小球藻属）仅在第2周和第13周占主导地位两次。虾塘中缺少一些沿海水微藻物种很可能是因为它们无法耐受恶劣环境的理化因素。在本研究中，圆柱角毛藻被认为是微藻中最耐受的物种，因为它在15周的养殖期内能够存活6周。
