4th Drop: Collapse of Ecosystem Services? Fisheries in Lake Victoria

HELLO ~ Hope everyone is doing well! It is less than 2 days till reading week and I definitely hope to be posting a bit more frequently over the next week *fingers-crossed*

Collapse of Ecosystem Services?

Anyway...We have been talking a lot on the positives of ecosystem services and how these benefits can be valued so as to help us achieve conservation goals. Perhaps it is a good opportunity for us to look on the flip-side; the repercussions of a collapsed ecosystem and hence disruption in provision of ecosystem services. A clear understanding of the negative repercussions and losses of ecosystem services should help paint an even more stark picture of the importance of ecosystem conservation.

Fisheries in Lake Victoria

'Catastrophic change in species-rich freshwater ecosystem' (Kaufman 1992) is a detailed case study that covers the ecosystem changes within Lake Victoria. More specifically the article takes a more ecological slant covering firstly on the freshwater ecosystem changes (trophic levels and food webs) within Lake Victoria, followed by the reasons behind these changes and lastly key lessons learnt. 

Briefly Lake Victoria should be understood in the context of other similar East African lakes, such as Lake Malawi and Lake Tanganyika, in that fish faunas within exhibit the products of rapid speciation from very few ancestors. A key native fish group within Lake Victoria that exhibits great biodiversity would be the fish family Cichlidae. In contrast the 'antagonist' within this story would be the Nile Perch which was introduced in 1954 but only underwent population explosions in the late 1980s.

Here are some key reflections:

1) Collapse of Freshwater Ecosystem: Result of a series of anthropogenic changes

• Over-fishing of native species within fisheries + intro of alien species (Nile Perch)
• Cessation of biological mixing and 'recycling' capacity as native species population diminished
• Land-use practices and pollution (esp. from agriculture activities)
• Eutrophication due to nutrient loading
• Resulting anoxia!! esp. in deeper parts of the lake
• Positive feedback? Anoxia leading to dwindling fish supply (both native and Nile Perch)

> It is easy to criticize these anthropogenic actions with the knowledge of hindsight. However what I do feel is a more critical learning point from the Lake Victoria case study is the need for proper ecological understanding of the ecosystem we are reliant on (and at times tempted to alter; much like the introduction of the Nile Perch). There is huge variability and complexity just from the ecological perspective, much less when the ecosystems in Africa are heavily influenced by hydrological variability as well. Hence conscientious monitoring and study to develop greater understanding of the ecosystems should be constantly done, so that an ecosystem service approach might be successful.

2) Impact on the Fisheries?

• Increase in Nile Perch actually a benefit to the Fisheries: More tonnage + More Valuable
• BUT what are the actual distribution of these benefits? Unequal!
• Local fisherman unable to exploit the more valuable Nile Perch resource (lack equipment)
• Malnutrition in the lake basin despite exporting nearly 200,000 tons of fish protein/ yr
• Locals complain about the lost of native fishes which has greater variety of taste and texture
• "analogous to the common practice of clearcutting rainforest and replacing it with one or a few fast-growing, easily processed, exotic timbers" => significant alteration of the ecosystem!
• What ecosystem services approach SHOULD NOT look like? As covered previously, ecosystem services are often part of a wider bundle of services provided by the ecosystem!

> Repercussions of collapse of ecosystems are thus clearly captured by the loss of the benefits provided by the ecosystem services. As covered previously, these services benefit individuals differently and dynamically - the same service can be altered without significant changes to the quantity but yet still have an important impact (eg. change from native fishes to Nile Perch). Valuation of ecosystem services would thus benefit from greater considerations of socio-economic context. More importantly it is easy to assume that only a particular service is loss from the collapse of an ecosystem but it is important to realise that there are other ecosystem services that are affected.

CHEERS for reading these reflections of mine and I hope they are helpful to you as well :)

~ Till Next Time ~

National Geographic Society Photo by Aerin Jacob