Shrimp Farms Face Rising Threats From Water Pollution
Aquaculture, a rapidly expanding global food source, is increasingly vulnerable to the toxic effects of common pollutants, threatening both shrimp populations and the livelihoods of farmers. New research details the specific damage caused by ammonia, nitrite, and sulfide.
Study Reveals Tissue Damage
A recent study led by **Lulu Han**, **Peiyu Yan**, and **Mengqiang Wan** investigated the impact of these three environmental stressors on Pacific white shrimp (Litopenaeus vannamei). Researchers found that increasing concentrations of these substances progressively harmed the shrimp’s hepatopancreas, midgut, muscles, and gills.
Pollutants and Shrimp Health
Environmental stresses are known to predispose shrimp to disease. Ammonia, originating from decomposing organic matter, inhibits growth and damages vital organs. Elevated nitrite levels, often caused by poor water circulation and excess feed, lead to abnormal growth and increased mortality. Sulfides, produced in anaerobic conditions, disrupt tissue integrity and weaken the immune system.
Experimental Setup
The study, conducted with shrimp obtained from Hainan Zhongzheng Aquatic Technology Co., Ltd., exposed groups of 80 shrimp to varying concentrations of each stressor. Researchers meticulously monitored survival rates and analyzed tissue samples over 132 hours, using spectrophotometry to track pollutant levels.
Survival Rates Decline
Survival rates generally decreased as stress time increased, with significant drops observed between 120 and 132 hours. While higher concentrations of ammonia reduced survival, the study noted the differences between the tested levels weren’t statistically significant, potentially due to a small concentration gradient.
Hepatopancreas Most Vulnerable
The hepatopancreas, shrimp’s primary digestive and immune organ, showed significant damage under all three stressors. This suggests a heightened burden on the organ to detoxify pollutants, leading to tissue damage. Nitrite stress appeared particularly harmful to the hepatopancreas, potentially impacting immune function and metabolism.
Midgut and Muscle Damage
All three chemicals caused damage to the shrimp’s midgut, with epithelial cell fragmentation and separation from the basement membrane. Nitrite appeared to most severely impact digestive enzyme secretion. Nitrite also caused significant muscle damage, including fragmentation and nuclear abnormalities.
Gill Health Compromised
Gill filaments became distorted and contracted with increasing ammonia concentrations, indicating escalating damage. Nitrite caused progressively greater gill filament contraction and cuticle rupture. The study suggests that severe tissue damage could impair gill function and lead to toxic metabolite accumulation.
Global Aquaculture Expansion
According to the Food and Agriculture Organization of the United Nations (FAO), global aquaculture production has increased from 37.5 million tonnes in 1990 to 87.8 million tonnes in 2022, highlighting the growing importance of sustainable practices.
Future Research Needed
The findings emphasize the critical need for careful water quality management in shrimp aquaculture. Future research will focus on the molecular and physiological mechanisms underlying these responses, aiming to develop strategies for enhancing shrimp resilience and ensuring the long-term sustainability of this vital food source.
