Fisheries and Aquaculture 2020 (SOFIA), aquaculture’s contribution to global fish production continues, reaching 82.1 million tonnes in 2018, accounting for 46% of Production Technology 53 the estimated 179 million tonnes of global fish production.
The impact of extreme rainfall on
Climate is always crucial to aquaculture; adequate rain can supplement water and aquaculture and its prevention improve culture water quality, while extreme rainfall can cause problems and huge There is an extensive list of events which can be managed with a good understanding of impact and losses. prompt action by farmers
By Li Bing, Dong Qiufen and Zhang Song
Heavy rains and dead fish after rains. Left: Rohu (Labeo rohita) pond in the rain in Myanmar. Right: Tonnes of dead fish were found floating on water surface near Jakarta after torrential rains (Daily Mail 2015).
quaculture plays a significant role in supplying aquatic Heavy rains and dead fish after rains. Left: Rohu (Labeo rohita) pond in the rain in A products which are important food sources for the global population. According to FAO’s State of World Myanmar. Fisheries and Aquaculture 2020 (SOFIA), aquaculture’s contribution to global fish production reachingfloating on water surface near Jakarta after Right: Tonnes of dead fish continues, were found 82.1 million tonnes in 2018, accounting for 46% of the estimated 179 million tonnesMail of global fish production. torrential rains (Daily 2015). Climate is always crucial to aquaculture; adequate rain can supplement water and improve culture water quality, while extreme rainfall can cause problems and huge losses.
In this article, we explore events in fish and shrimp farming, with the occurrence of rains and what we can toand reduce the negative impacts. In this article, we explore eventsdo in fish shrimp farming, with the occurrence of rains and what we can do to reduce the negative impacts.
TheThe dynamic processes dynamic processes Figure 1. Effects of rain on the water environment and pond Duringrainy rainy periods, rainwater and run-offand will mix with ecosystem During periods, rainwater run-off will mix with the original pond water. the original pond water. While sunlight will be blocked by rain clouds, at will the same the air temperature will While sunlight betime, blocked by rain clouds, at the same time, the air temperature be lower. The atmospheric pressure is usually quite low the earlyThe part ofatmospheric the rains and sometimes occursis usually quite low during the early part of willduring be lower. pressure with strong winds. Besides these direct effects on the water will also lead to water movements on theenvironment, rains andrains sometimes occurs with strong winds. Besides these direct effects on the pond surface and at the pond bottom, further affecting thethe water rains will to water movements on the pond surface state ofenvironment, the pond environment (Figure 1). also leadpH The suitable pH in pond culture water is around 7.0-8.5, andWater at the pond bottom, further affecting the the pond environment (Figure while state the pH ofof most rainwater is below 6.6 and can be much temperature water temperatures often drop with heavy rain. lower with acid rain (Vet, 2014). Moreover, photosynthesis 1). Pond According to Rooney et al. (2018), rain may have effects will be affected due to poor conditions for algae development on the pond water surface in four ways: evaporation and cooling of the near water surface-air during precipitation; direct rain heat fluxing into the pond; mixing of the pond surface layer through the flux of kinetic energy; and finally, convection mixing of the pond surface layer. Research indicated that during the days with heavy rainfall, there may be a reduction in lake surface temperatures of approximately 0.3°C by the end of the day compared to the days with light and moderate rainfall. Location Jordan Italy Tirupati, India Newark, USA Shanghai, China
Ca2+ 165.3 5.18 150.7 6.0 204.0
Mg2+ 93.12 70 55.51 3.3 29.6
Na+ 130.6 77 33.08 10.9 50.1
K+ 85.21 17 33.89 1.3 14.9
and diminished sunlight during rains. The pH will then be more than 1.0 after the rains.
Salinity
The mineral content in rainwater is low, although the run-off may carry some minerals. After extreme rain, the salinity declines in full seawater and brackish water bodies, as shown in Table 1.
NH4+ 75.36 25 20.37 24.4 80.7
Reference O.A. Al-Khashman, 2005 Le Bolloch, 1995 P. Mouli, S. Mohan, 2005 F. Song, 2009 X. F. Huang, 2010
Table 1. Chemical analyses of rainwater in various locations (in μeq/L).
July/August 2022 AQUA Culture Asia Pacific
