Ecosystem Dis-services

While ecosystem services (ES) are ecosystem functions (EF) which can become ES by contributing to human well-being, ecosystem dis-services (EDS) can have negative impacts. Although the concept of ecosystem dis-services is a relatively new one, negative impacts of nature have been recognised for as long as there have been humans (see ecosystem dis-functions in the spiral). EDS may cover such diverse phenomena as natural hazards, such as floods caused by overgrown riverine vegetation, toxic algal blooms and allergenic pollen. Other examples are diseases vectored by other organisms within the ecosystem, such as mosquito-borne diseases like malaria or parasitic helminths. ES which support animal life in the vicinity of humans may nevertheless result in the spread of zoonoses, which through regular exposure can evolve into human pathogens. Historical examples including human immunodeficiency virus and the 1918 influenza pandemic.

Most EDS are significantly less dramatic, however. Urban and agricultural ecosystems are where most human-ecosystem interactions occur. Here, many EDS can mirror ES. For example, ant species belonging to the genus Philidris closely associate with a plant host, and carry out a number of ES in fruit orchards, including predation of pest capsid bugs (Helopeltis spp.). However, these ants also cause a number of EDS, including spreading fruit diseases and suppressing other predators of insect pests (Wielgloss et al. 2014). In urban ecosystems, bird species provide an array of ES, including regulatory ones such as the control of insect populations as well as cultural benefits as birds can contribute to a more pleasant environment. However, some bird species also contribute cultural EDS through destruction of property (Belaire et al. 2015). Human-induced changes to the freshwater ecosystem of Lake Malawi in Africa resulted in increased EDS, specifically increasing populations of benthic snails (Bulinus nyassanus Smith 1877) which are a vector for the parasitic helminths Schistosoma spp. (van Bocxlaer et al. 2014). These human-induced effects are thus responsible for a concomitant rise in schistosomiasis (bilharzia). This case illustrates how human changes to ecosystems can make an existing EDS even worse.

Examples of Ecosystem Dis-services:

Argentine ants (Linepithema humile Mayr) protecting a mealybug (Pseudococcus viburni Signoret) against a parasitoid (Leptomastix epona Walker), which is killed by the ant before it can lay eggs inside the mealybug. Video: Kent Daane, University of California-with permission.

Birds can delight humans with their songs (an ecosystem service), but can annoy them as well with their faeces, often below roosting sites.

References

Belaire J, Westphal L, Whelan C, Minor E, 2015. Urban residents’ perceptions of birds in the neighbourhood: Biodiversity, cultural ecosystem services, and disservices. Condor, 117: 192-202.

van Bocxlaer B, Albrecht C, Stauffer J, 2014. Growing population and ecosystem change increase human schistosomiasis around Lake Malaŵi. Trends in Parasitology, 30: 217-220.

Wielgoss A, Tscharntke T, Rumede A, Fiala B, Seidel H, Shahabuddin S, Clough Y, 2014. Interaction complexity matters: disentangling services and disservices of ant communities driving yield in tropical agroecosystems. Proceedings of the Royal Society B: Biological Sciences 281: 20132144.