The impact of aquaculture expansion on Lake Burullus, a Ramsar site in Egypt

Lake Burullus is a brackish lake in the Nile Delta in Egypt. It is located in Kafr el-Sheikh Governorate, east of Rosetta, and is bordered by the Mediterranean Sea in the north and agricultural land in the south.

The lake is considered to be a wetland site of International Importance for birds under the Ramsar Convention. Agricultural drainage water accounts for 97% of the total inflow to the lake (3.9 billion m3 per year), followed by rain water (2%) and groundwater (1%). 16% of the lake’s water evaporates and 84% flows to the sea. [1]

According to a Biodiversity Report of the Egyptian Environmental Affairs Agency, 33 species of fish, 23 species of reptiles, 112 species of birds, and 18 species of mammals live in and around the lake. Fish species in the lake have undergone significant declines since the beginning of the 20th century when 52 different species were recorded. This is mostly due to the inflow of agricultural drainage into the lake resulting in lower salinity.

The increase of aquaculture and decrease of the total open water surface area of Lake Burullus

The most important issue for the lake is the increase of aquaculture. These aquaculture ponds have a negative impact on the total open water surface area of the lake and on fishing opportunities for communities living around the lake who depend on catching fish for their survival.

The maps on Land Use Land Change and Surface Water Dynamics (LULC and SWD) produced within the scope of the SWOS project clearly show the introduction and subsequent huge expansion of aquaculture ponds between 1973 and 2015 in and around Lake Burullus. The most notable expansion occurs between 1973 and 1990 (from 0 to over 40,000 ha). After 1990, the total size of the aquaculture decreases somewhat, but remains high at around 30,000 ha. The LULC maps also show an increase in reed beds (roughly +40% between 1973 and 2015) at the expense of salt marsh vegetation (roughly -80% between 1973 and 2015), an indication of eutrophication caused by the inflow of drainage water from the aquaculture ponds and agricultural lands surrounding the lake.

Aquaculture has caused a reduction in Lake Burullus’ open water surface area. In 1810 the recorded size of the lake’s open water surface was 100,000 ha. The SWOS maps show a decrease in open surface water area from roughly 45,000 ha in 1973 to 25,000 ha in 2015.

The expansion of aquaculture has impacted significantly the ecosystem services the Lake provides. This includes:

  • A decreased fish catch (the main source of income of the local population).
  • The capacity of the lake to purify waters is decreasing.
  • The expansion of aquaculture is at the expense of reed beds.
  • Expansion of aquaculture decreases the possibility to harvest medical plants which provide an important source of income for the local population.
  • The expansion of aquaculture in the lake decreases the water retention capacity of the lake.
  • The decreasing lake surface area and especially the disappearance of shoreline vegetation has significant negative impacts on biodiversity.

By Eric van Valkengoed, TerraSphere BV

[1] Source: Wikipedia, Lake Burullus. Accessed on 18 June 2018.