Ecosystem Service Valuation of Lakes & Rivers

When excessive nutrients enter bodies of water through sources such as agricultural runoff or wastewater effluent, this causes an environmental phenomena known as eutrophication. This process of eutrophication can be extremely harmful for aquatic ecosystems because primary production increases dramatically when those excess nutrients are absorbed by aquatic vegetation (typically algae), which can quickly change the relative abundance, taxonomic composition and spatial distribution of primary producers in the ecosystem. This alteration can throw the aquatic ecosystem off balance, negating the beneficial functions that the ecosystem offers. 

An ecosystem service valuation is the term for the process of quantifying the value of the ecosystem service benefits to people provided by a given identified region, typically calculated in terms of dollars. Ecosystem service valuation is not a new concept, with its popularity significantly increasing over the past two decades. 

Aquatic ecosystems, specifically lakes and rivers, provide extremely valuable and abundant ecosystem services. Eutrophication, however, directly affects the aquatic ecosystem service benefits, for it  has multidimensional consequences linked to environmental, social, and economic activities. 

Based on geographic location and specific ecosystem type, the list of ecosystem services affected by eutrophication generally consist of the following: 

1. Human health

2. Water Quality

3. Flood Mitigation

4. Fishing Industry

5. Ecological Biodiversity 
   

6. Drinking Water Supply

7. Nature-based Tourism and Recreation

8. Real Estate

9. Aesthetic Beauty

10. Nutrient Cycling

A Sample Effect of Increased Nutrient Load to Aquatic Systems

Note. Sourced from Dodds et al., 2009

These ecosystem services provide tangible economic value to communities and generate both monetary and environmental and social benefits to the region. But how does eutrophication more clearly affect these services?

Eutrophication of lakes commonly results in reduced ecological specialization and genetic and phenotypic homogenization within lake communities, thus decreasing species diversity and decreasing the long-term resiliency of the ecosystem. This can further lead to a decreased carry capacity and lower resource-use efficiency by human consumers. 

The estimated monetary value of rivers and lakes is approximately $15,618 per hectare per year. With an estimated average of 326 million hectares of global freshwater lake surface, the monetary value of lake ecosystem services equates to about $5.1 trillion per year. However, the minimum ecosystem losses from human impact are estimated to be about $970 billion per year, or approximately $120 per capita globally. Specifically in the US, it is estimated that eutrophication in freshwaters costs about $2.2 billion each year in recreational water use, waterfront real estate, spending on recovery of threatened and endangered species, and drinking water expenses. Additionally, an estimated 60 currently-listed endangered or threatened species are listed as at least partially imperiled due to eutrophication. 

It is important to note that not all of these ecosystem reductions are a result of eutrophication; however,  eutrophication can be a direct contributor to ecosystem service decline. Lake eutrophication has become one of the major ecological and environmental problems faced by lakes, leading to a series of abnormal ecosystem responses including extinction of submerged vegetation, harmful cyanobacteria blooms, decreased biodiversity, nutrient regulation issues, and declining real estate and tourism values. Overall, eutrophication from anthropogenic activities is associated with hypoxia and harmful algal blooms, compromising a variety of ecological and ecosystem services.