testmap has moved to TACAR. Please check the newest advances here: https://github.com/darrennorris/TACAR .
Use the interactive map below to check population changes. Zoom in to see where Podocnemis unifilis is Endangered based on IUCN Red List criteria - A3bd.
- Overall Podocnemis unifilis is Endangered (“Em perigo” /
“En peligro”) based on future population size reduction criteria -
A3bd.
Within 3 generations (35 years) the adult female population is predicted to decline by 50.7% in the future (25 and 75% quantile range: 51.8 - 49.7 % decline). Within 100 years the adult female population is predicted to decline by 63.4%.
Map
Due to the number of points, the map can become slow to respond when you zoom in. Zoom out to a level showing fewer points and you can pan around the map to find the area of interest. Then zoom in again to check the coloured points.
If you find any errors (e.g. points where Podocnemis unifilis does not occur, points where species is “Endangered” but populations are increasing etc) please raise an issue at: https://github.com/darrennorris/testmap/issues .
When you zoom in you will see shaded points.
The points are brown where populations are predicted to decline by 50% or more within 3 generations (35 years). Brown points therefore represent rivers where the species is Endangered (“Em perigo” / “En peligro”), following the IUCN Red List population size reduction criteria - A3bd (https://www.iucnredlist.org/about/faqs).The points follow rivers mapped by remote sensing. This standardized global scale mapping comes from Grill et al 2019, Free-flowing Rivers: https://doi.org/10.1038/s41586-019-1111-9. The points are locations along rivers selected to represent where Podocnemis unifilis females are likely to nest and that are likely to be accessible to people by boat. To facilitate online viewing the mapped points are a subset at intervals of approximately 10 kilometers.
Methods
The analysis is developed here: https://github.com/darrennorris/TACAR, The methods used are an extension of Norris et. al. 2019 that includes:
- Stochastic population projections.
- Future impacts to populations caused by human acessibility (hunting) and actions that reduce river connectivity.
Summaries
A summary of the map results is presented below. These include summaries by country and major basin using the full set of points at 1 kilometer intervals. To date subpopulations have not been identified due to a lack of comprehensive genetic analysis. Summaries by basin are provided as these are expected to represent important conservation management units for this predominantly aquatic species. The implementation of conservation actions is regulated at national levels so summaries are also provided by country.
- Results include the size and extent of future population
changes.
The column “population change” is the difference in the number of adult females after 3 generations (35 years). This is consistent with the population size reduction criteria used by the IUCN Red List. The column “River length Endangered”, is the proportion of river length where populations declined by 50% or more, and represents the spatial extent of future changes.
Summary by country.
| Country | Population change | River length Endangered (prop) | River length (km) |
|---|---|---|---|
| Bolivia | -0.53 (-0.54 – -0.52) | 0.70 | 22217 |
| Brazil | -0.51 (-0.52 – -0.5) | 0.61 | 190555 |
| Colombia | -0.47 (-0.48 – -0.46) | 0.61 | 38552 |
| Ecuador | -0.7 (-0.71 – -0.69) | 0.85 | 8302 |
| French Guiana | -0.44 (-0.45 – -0.43) | 0.62 | 3298 |
| Guyana | -0.29 (-0.3 – -0.28) | 0.44 | 7372 |
| Peru | -0.63 (-0.64 – -0.62) | 0.77 | 47363 |
| Suriname | -0.3 (-0.31 – -0.29) | 0.46 | 5756 |
| Venezuela | -0.37 (-0.38 – -0.36) | 0.56 | 30022 |
| Total | 353437 |
Summary by basin.
In the table below “Amazon” includes the Amazon Basin together with the Araguaia-Tocantins Basin in Brazil. “Coastal North” covers the Guianas and includes the Essequibo Basin. “Coastal South” includes part of Maranhão State in Brazil.
| Basin | population change | River length Endangered (prop) | River length (km) |
|---|---|---|---|
| Amazon | -0.518 (-0.53 – -0.51) | 0.63 | 280121 |
| Coastal North | -0.339 (-0.35 – -0.33) | 0.50 | 20835 |
| Coastal South | -0.808 (-0.81 – -0.8) | 0.94 | 6467 |
| Orinoco | -0.474 (-0.48 – -0.46) | 0.64 | 46014 |
Summary by major basins and countries.
| Basin | Country | population change | River length Endangered (prop) | river length (km) |
|---|---|---|---|---|
| Amazon | Bolivia | -0.53 (-0.54 – -0.52) | 0.70 | 22217 |
| Amazon | Brazil | -0.5 (-0.51 – -0.49) | 0.60 | 180434 |
| Amazon | Colombia | -0.37 (-0.38 – -0.35) | 0.52 | 18687 |
| Amazon | Ecuador | -0.7 (-0.7 – -0.69) | 0.85 | 8302 |
| Amazon | Guyana | -0.83 (-0.83 – -0.82) | 0.89 | 423 |
| Amazon | Peru | -0.63 (-0.64 – -0.62) | 0.77 | 47363 |
| Amazon | Venezuela | -0.02 (-0.03 – -0.02) | 0.22 | 2695 |
| Coastal North | Brazil | -0.41 (-0.42 – -0.4) | 0.55 | 3653 |
| Coastal North | French Guiana | -0.44 (-0.45 – -0.43) | 0.62 | 3297 |
| Coastal North | Guyana | -0.26 (-0.27 – -0.25) | 0.41 | 6928 |
| Coastal North | Suriname | -0.3 (-0.31 – -0.29) | 0.46 | 5756 |
| Coastal North | Venezuela | -0.49 (-0.5 – -0.48) | 0.72 | 1201 |
| Coastal South | Brazil | -0.81 (-0.81 – -0.8) | 0.94 | 6466 |
| Orinoco | Colombia | -0.57 (-0.58 – -0.56) | 0.70 | 19865 |
| Orinoco | Venezuela | -0.4 (-0.41 – -0.39) | 0.58 | 26126 |
The table values can also be presented graphically. This enables a clearer understanding of the patterns.
Figure 1. Population changes across basins and contries.
The grey bars in the above figure show predicted population changes for each basin country combination. The width of the bars is proportional to the river length on a log scale. The labels above each bar show river lengths in thousands of kilometers (e.g. “22.2” is 22,200 kilometers). The background shading follows a gradient from Near Threatened (“-0.2” is 20% loss) to Critically Endangered (“-0.8” is 80% loss).
The Amazon Basin in Brazil represents the largest proportion of rivers (51.1%). Considering the spatial variation in threats and genetics, it would probably be useful to include the Amazon Basin seperated into major basins (Madeira, Negro, etc). But the summaries presented here provide a general overview and enable assessment of the results, and the overall patterns do not change if the Amazon basin is seperated further.