The case study by Cunha, Bottino and Calijuri (2010), examined how land use patterns within the Ribeira do Iguape watershed, Sao Paulo, Brazil, with varied levels of anthropogenic interference influenced eutrophication variables (total suspended solids (TSS), total phosphorus (TP), chlorophyll-a (Chl-a) and total nitrogen (TN)) ranges in three rivers (Canha, Pariquera-Acu and Jacupiranguinha Rivers). Eutrophication is one of the major problems affecting freshwater ecosystems because it restricts water usage, which may lead to environmental and socio-economic repercussions (Dodds 2006). In Sao Paulo, the key drivers of cultural eutrophication in most watersheds …show more content…
The high Chl-a levels in Jacupiranguinha River is related to the extreme levels of point source of pollution and reduced forest cover through their conversion into banana plantations. The Jacupiranguinha River had the highest TSS levels (100.1 mg/L), because of the high concentrations of agricultural and urban activities in this section of the watershed (Cunha, Bottino, and Calijuri 2010). In the Jacupiranguinha River, high TSS levels have reduced phytoplankton productivity and may decrease benthic macroinvertebrates and fish diversity (Bilotta and Brazier 2008). Although, low TSS levels were recorded in the Pariquera-Acu and Canha Rivers, it may still affect aquatic life. Even though Pariquera-Acu River is unaffected by industrial effluents, it still receives stabilisation pond effluents due to the high TN levels recorded, because these ponds are inefficient in the removal of nutrients from wastewater (Cunha, Bottino, and Calijuri 2010). In the Pariquera-Acu River, domestic effluents may increase oxygen demand and reduce dissolved oxygen levels, which can decrease fish diversity. The Cahna River is subjected the least to anthropogenic impacts compared to the other