* By Aquaculture Magazine Editorial Team
As India leads global shrimp production, innovative practices like high-density polyethylene (HDPE) ponds are reshaping aquaculture. This study compares water quality and plankton productivity in HDPE versus traditional earthen ponds in Ratnagiri, Maharashtra. Results reveal significant differences in key hydrobiological parameters suggesting that HDPE ponds offer better environmental control and improved productivity.
India is a global leader in shrimp production due to rapid growth rates, shorter cultivation periods, high export value, and increasing market demand. Meeting this demand requires expanding farming areas and adopting innovative methods to improve productivity and close the supply-demand gap. Shrimp production is significantly influenced by the water´s physico-chemical characteristics, which affect shrimp growth and survival. In particular, hydrogen ion concentration (pH) in both water and pond soil are critical, as are nutrient inputs that can deteriorate water quality if retained or degraded.
Monitoring water quality is essential for both shrimp health and farm productivity, yet pond management often lacks adequate attention. Since shrimp physiology depends heavily on water temperature, farming protocols must be adjusted accordingly. In tropical and subtropical regions, phytoplankton play a vital role in maintaining energy balance and water quality, with seasonal and climate-driven fluctuations affecting their populations. Because phytoplankton perform photosynthesis and generate oxygen, they are key indicators of primary productivity and serve as a natural food source for shrimp. Zooplankton also contribute significantly by linking primary producers with higher trophic levels.
However, challenges like poor soil quality and disease make shrimp cultivation in traditional earthen ponds difficult. To address this, farmers have started using Litopeneaus vannamei in lined ponds. These alternatives, particularly high-density polyethylene (HDPE) liners, offer benefits such as improved disease control and suitability in acidic soils, outperforming traditional systems. HDPE ponds are also easier to manage. This study compares earthen and HDPE ponds regarding water quality and plankton productivity to evaluate their relative efficiency in shrimp farming.
Materials and Methods
The present study was conducted between June to October 2022 and January to May of 2023. Samples of water and plankton were collected from Kelbai Aqua farm Ranpar, Ratnagiri, including two consecutive crops from four earthen and four high-density polyethylene (HDPE) ponds. Weekly water samples were collected from the farm, assessing pH, salinity, temperature, biochemical oxygen demand, dissolved oxygen, alkalinity, hardness, ammonia, nitrite-nitrogen by Strickland and Parsons (1972), Boyd (1979). Primary productivity using standard light and dark bottle method (Gaarder and Gran, 1927).
Plankton samples were collected at 7-day intervals from ponds by filtering 50 L of water using a 50 μm mesh net and preserved in Lugol’s solution and a 5% neutralized formalin solution for future analysis. In the laboratory analyzed phytoplankton and zooplankton qualitatively by pipetting 1 ml sample and quantitatively using Sedgewick-Rafter density per liter of water samples, observing under microscope at 10x and 40x magnification and identifying plankton using a taxonomic key (Newell and Newell, 1977).
The Analysis of Variance (ANOVA) was performed using SPSS 16.0 software to determine the statistical significance (p < 0.05) of the effect of pond types and experiment days on water quality parameter, primary productivity and plankton.
Results and Discussion
Water quality parameters
For both crop cycles, the ANOVA showed significant differences (p < 0.05) in temperature, pH, salinity, dissolved oxygen (DO), and alkalinity between earthen and HDPE ponds (Table 1). Total hardness, total ammonia, and nitrite-nitrogen showed significant differences for crop one (Table 1) but not for crop two (p > 0.05). Biochemical Oxygen Demand (BOD) differed significantly only for crop two.
Primary productivity and plankton
ANOVA revealed significant differences (p < 0.05) in Gross Primary Productivity (GPP) and Community Respiration (CR) between pond types for crop one (Table 1) , but no difference for crop two. Net Primary Productivity (NPP) showed significant differences in both crops.
Temperature and pH
Temperature impacts shrimp growth and metabolism. Ranges were 27- 31°C in both pond types. Ideal shrimp growth occurred at 26-30°C. For earthen ponds, the optimal range was 26.34-28.69°C; for HDPE ponds, 26.93-28.96°C. Temperature showed-positive correlation with GPP, NPP, CR, and plankton (Figure 1). The water pH remained within the ideal range (6.6-8.5). Measured values ranged from 4.5 to 8.7 depending on pond type and season. Mean values ranged from 7.9 to 8.1 in both pond types, correlating negatively with plankton and productivity.
Salinity and dissolved oxygen
Salinity ranged from 21.52-40.21 practical salinity unit (PSU) in earthen and 21.93-39.58 PSU in HDPE ponds, optimal for shrimp growth. Salinity correlated negatively with plankton and productivity. DO ranged from 4-7 mg/L. Mean values were 4.6-5.0 mg/L in earthen and 4.7-5.3 mg/L in HDPE ponds, suitable for L. vannamei. DO positively correlated with GPP, NPP, CR and zooplankton in crop one, but showed mixed trends in crop two.
Biochemical oxygen demand and alkanility
BOD values ranged between 3.33-4.06 mg/L (earthen) and 3.38-4.45 mg/L (HDPE). These values indicated suitable pond conditions. BOD correlated positively with plankton and productivity. Alkalinity ranged from 66.56-96.82 mg/L (earthen) and 76.57-115.50 mg/L (HDPE), supporting shrimp health. Seasonal variability was noted due to monsoonal freshwater input. Alkalinity positively correlated with plankton and productivity.
Hardness, ammonia and nitrite
Total hardness ranged from 3,334.7- 6,313.0 mg/L (earthen) and 3,379.8- 6,320 mg/L (HDPE). Hardness negatively correlated with productivity in crop one and positively in crop two for GPP, NPP, and zooplankton. Ammonia levels were higher in earthen (0.6-0.7 mg/L) than HDPE ponds (0.4- 0.5 mg/L). Ammonia negatively correlated with CR and positively with GPP, NPP, and plankton in crop one. In crop two, it remained positively correlated with productivity.
Nitrite-nitrogen ranges from 0.1189-0.502 mg/L (earthen) and 0.1056-0.1671 mg/L (HDPE). Ideal levels (~0.01-0.1 ppm) were occasionally exceeded. Nitrite was positively correlated with productivity and plankton, and negatively with CR during crop one. Similar positive trends were found in crop two.
Primary productivity
» Gross Primary Productivity (GPP). GPP values ranged from 0.8540-0.9153 mg C/L/hr (earthen) and 0.7991-1.0677 mg C/L/hr (HDPE). GPP was highest pre-monsoon and lowest and lowest during monsoon. It correlated positively with temperature, alkalinity, BOD, ammonia, and nitrite and negatively with pH, salinity, and hardness in crop one; similar trendswere observed in crop two.
» Net Primary Productivity (NPP). NPP ranged from 0.6896-0.8353 mg C/L/hr (earthen) and 0.6855- 0.9254 mg C/L/hr (HDPE). Higher NPP occurred in summer. Correlation trends matched those of GPP.
» Community Respiration (CR). CR ranged from 0.0798-0.1724 mg C/L/hr (earthen) and 0.0929-0.1411 mg C/L/hr (HDPE). Higher respiration was attributed to biotic activity. CR positively correlated with temperature, DO, alkalinity, BOD; negatively with Ph, salinity, hardness, ammonia, and nitrite.
Plankton
Phytoplankton and zooplankton are key nutritional sources for aquatic larvae. In this study, phytoplankton density ranged from 80 to 5,550 Nos. L-¹ across various ponds. These values align with previous research in tiger shrimp ponds. Dominant phytoplankton groups included Bacillariophyceae, Dinophyceae, Cyanophyceae, and Chlorophyceae, with species such as Actinoptychus, Coscinodiscus, Nitzchia, Oscillatoria, Nostoc, Gymnodinium, and Prorocentrum were observed.
Zooplankton density ranged from 30 to 320 Nos. L-¹, with primary groups being protozoans, copepods, and rotifers. Key protozoans included Tintinnopsis, Favella, and Vorticella. Rotifers were dominated by Branchionus, Keratella, and Lecane, while copepods included Acartia, Calanus, Cyclops, and Microsetella. Similar species distributions have been reported in other shrimp ponds across Tamil Nadu, including findings of crustacean nauplii, mysidacea, and pelagic polychaetes.
Overall, plankton populations showed positive correlations with temperature, dissolved oxygen, alkalinity, hardness, and biological oxygen demand, while pH and salinity were negatively correlated (Figure 2). These results highlight the ecological dynamics and water quality interactions influencing primary productivity in shrimp aquaculture systems.
Conclusion
The research included information on hydrobiological assessments and management role of shrimp farmers located in Ratnagiri, Maharashtra. The results of this investigation indicated that most hydrobiological parameters were within the optimal recommended ranges found in the published literature. It was observed that the shrimp growth and survival rates appeared to benefit for the high-density polyethylene (HDPE) ponds, which leads to increased production efficiency over traditional earthen ponds. The experimental observations recorded during the specified period can be utilized as reference by other entrepreneurs from the Konkan region of Maharashtra, as our findings provide them with the necessary information and knowledge to implement effective management practices for shrimp culture in the future.
This informative version of the original article is sponsored by: REEF INDUSTRIES INC.
This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “COMPARATIVE STUDY OF HYDROBIOLOGICAL PARAMETERS BETWEEN EARTHEN AND HIGH-DENSITY POLYETHYLENE (HDPE) BRACKISHWATER SHRIMP PONDS IN RATNAGIRI, MAHARASHTRA” developed by: Kawade, S.S. – College of Fisheries (DBSKKV) Ratnagiri Maharashtra; Sapkale, P. H. – Taraporevala Marine Biological Research Station; Sawant M.S. and Dhamagaye, H.B. – College of Fisheries (DBSKKV) Ratnagiri Maharashtra; Gangan, S.S. – Taraporevala Marine Biological Research Station and Chauhan, S. – College of Fisheries (DBSKKV) Ratnagiri Maharashtra. The original article, including tables and figures, was published on SEPTEMBER, 2024, through ENVIRONMENT AND ECOLOGY. The full version can be accessed online through this link: https://doi.org/10.60151/envec/ZKTJ1135
