International Society of Limnology (SIL) Congress, Italy (2016)

  1. Thornhill, I., Heasley, E., Fernandes Cunha, D. G., Loiselle, S., Land-use impacts upon turbidity within streams in the Americas are effectively recorded by citizen science as well as remotely sensed data. International Society of Limnology ‘Science for Sustainable Freshwater Use’, Torino, Italy. July 2016.
  2. Loiselle, S., Felipe Velasquez, L., Ophof, D., Thornhill, I. The importance of local scale factors in phytoplankton and nutrient dynamics in urban freshwater ecosystems. International Society of Limnology ‘Science for Sustainable Freshwater Use’, Torino, Italy. July 2016.

Abstract 1:
High levels of turbidity influence important ecosystem processes such as photosynthesis and predator-prey relationships. Increased suspended sediment load can also be a direct cause of fish and invertebrate mortality, particularly at egg and larval stages. Suspended sediment is sourced from catchment soils which are eroded during precipitation events and transported to the river via run-off. More naturalised catchments increase the opportunity for interception of run-off through vegetation growth. On the contrary, human activities such as urbanisation or deforestation are likely to reduce the catchments ability to buffer impacts to the river as the proportion of naturalised
land-cover decreases.

Contextual data relating to the local physical environment were collected alongside standardised measurements of turbidity by trained citizen scientists across six North and South American cities between April 2013 and January 2016. For both contextual and remotely sensed catchment land-use data, turbidity increased along with the proportion of built space (e.g. residential) whilst lower levels were associated with grass and shrub land. When compared to remotely sensed land-cover data, locally collected land-use information was most indicative for lower order stream samples. The strength of the relationship between local land-use information and turbidity reduced, though remained significant, relative to catchment scale data as stream order increased.
This research highlights the valuable contribution citizen science can make to our understanding of river dynamics and adds weight to the need consider the impact of surrounding land-use upon water quality.

Abstract 2:
Urban freshwater ecosystems are subject to a wide range of potential impacts, often leading to their degradation and loss. Many are small and fragmented with only limited monitoring. As limnologists, we do not have sufficient information to identify the temporal and spatial dynamics of these waterbodies, nor to identify the local and regional scale drivers that lead to their degradation. Such information is sin qua non to finding solutions to their increasingly widespread degradation. One source of additional ecological and geographic data is that acquired by citizen scientists –volunteers with basic training in data collection and ecosystem analysis.

In the present study, we show how trained and supported citizen scientists can provide key data to understand the drivers of eutrophication and ecosystem degradation in urban freshwater ecosystems. We show how high resolution microscale datasets (12,000) gathered by citizen scientists on water quality, land use and pollution sources can be combined with low resolution satellite- based data on land cover and population to help predict the dynamics of water quality and ecosystem conditions. We show clear relationships between eutrophication metrics (phytoplankton density, nutrient concentrations) and potential drivers across a range of environments on five continents.

The results indicate that microscale data from trained citizen scientists provides powerful basis to determine the spatial and temporal dynamics of urban freshwater ecosystems. The availability of complementary citizen generated data will grow in
importance as the proportion of people living in urban areas increases. Citizen observatories help us meet linked challenges of improving our understanding of aquatic environments and restoring the connection between human populations and their local ecosystem.


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