Future trajectory
In the near future, the Seychelles will likely see four major implications of human driven change: climate change, invasive species, biophysical limitations and private development. The way that tortoise populations manage to respond to these changes may vary greatly based upon future levels of human stewardship – or the potential lack thereof.
Perhaps the most significant threat to the tortoises is climate change. Climate change will impact the islands and their associated ecology in several ways including: the loss of physical land-mass, changes in species composition, weather (precipitation, temperature) and other factors. If the habitat that the tortoise depends on is not able to either adapt to these changes or to migrate where conditions will stay favourable, tortoises will be wholly dependent on human support in the future for survival.
The rising of sea levels may be the largest threat to small islands such as the Seychelles. Island nations are particularly vulnerable to the effects of sea level rise, which has been tied to increases in coastal flooding, increased coastal erosion, and the salinization of surface and groundwater sources (Sandwell, 2011, 7). These effects may serve to drive many citizens to migrate inland and upslope, as approximately 90% of the Seychelles population is located at an average of 2m above sea level, with the sea level predicted to rise almost 0.5m in the next century (Payet, 2009, 17). These citizens may cause additional stress to terrestrial ecosystems on inhabited islands as human populations develop or expand into areas that were previously uninhabited in order to stay above the rising water level. In addition to the terrestrial effects, “sea level rise and increased frequency of extreme weather events may contribute significantly to the loss of biogenic beaches and other coastal areas through inundation and coastal erosion” (UNEP, 2014, 16) – which may threaten the fisheries of the Seychelles, thereby threatening food security and increasing pressures to either exploit natural areas or to develop natural areas into agricultural area, threatening the habitats of giant tortoises.
One of the direct impacts of climate change on all Chelonians (turtles, tortoises, etc.) is that temperature can directly impact reproductive patterns and results. Not only does temperature regulate the egg development but it plays a role in the sex selection of juvenile tortoises (Ihlow et al, 2012). Slow gradual changes in climate over millions of years allow the Chelonians to adapt or migrate to suitable conditions; however if the climate is expected to change by up to 5oC within the end of the century (IPCC, 2014), and if temperature plays a role in the sex selection of tortoises (Ihlow et al, 2012), then tortoise populations may experience a severe imbalance between males and females in the future.
The Giant tortoises have been re-introduced on a few of the Seychelles including: Frégate, North, and Cousine. Unfortunately, residents and property owners of Silhouette Island refused to have wild tortoises roam free on the island, consequently the tortoises had to be moved to neighbouring islands of North, Cousine, and Frégate (Gerlach). Furthermore, North refused to accept all of the refugee tortoises and so Frégate was given the majority of the tortoises. Consequently, one of the greatest threats to the tortoises throughout the Seychelles appears to be non-conservation minded landowners resulting in extirpation and removal of the tortoises. Luckily, the tortoise protection program on Frégate was developed to help preserve the tortoises as a tourist attraction. Although this solution may not last a millennia, in light of climate change, human managed tortoise breeding programs that are accessible on islands with resorts targeted towards eco-tourists may actually be the best option for the tortoises given that rapid changes may soon occur (Gerlach et al, 2013). In this case, the breeding programs may be better funded than otherwise, and the resorts have an active interest in acting as stewards of the island.
Perhaps the most significant threat to the tortoises is climate change. Climate change will impact the islands and their associated ecology in several ways including: the loss of physical land-mass, changes in species composition, weather (precipitation, temperature) and other factors. If the habitat that the tortoise depends on is not able to either adapt to these changes or to migrate where conditions will stay favourable, tortoises will be wholly dependent on human support in the future for survival.
The rising of sea levels may be the largest threat to small islands such as the Seychelles. Island nations are particularly vulnerable to the effects of sea level rise, which has been tied to increases in coastal flooding, increased coastal erosion, and the salinization of surface and groundwater sources (Sandwell, 2011, 7). These effects may serve to drive many citizens to migrate inland and upslope, as approximately 90% of the Seychelles population is located at an average of 2m above sea level, with the sea level predicted to rise almost 0.5m in the next century (Payet, 2009, 17). These citizens may cause additional stress to terrestrial ecosystems on inhabited islands as human populations develop or expand into areas that were previously uninhabited in order to stay above the rising water level. In addition to the terrestrial effects, “sea level rise and increased frequency of extreme weather events may contribute significantly to the loss of biogenic beaches and other coastal areas through inundation and coastal erosion” (UNEP, 2014, 16) – which may threaten the fisheries of the Seychelles, thereby threatening food security and increasing pressures to either exploit natural areas or to develop natural areas into agricultural area, threatening the habitats of giant tortoises.
One of the direct impacts of climate change on all Chelonians (turtles, tortoises, etc.) is that temperature can directly impact reproductive patterns and results. Not only does temperature regulate the egg development but it plays a role in the sex selection of juvenile tortoises (Ihlow et al, 2012). Slow gradual changes in climate over millions of years allow the Chelonians to adapt or migrate to suitable conditions; however if the climate is expected to change by up to 5oC within the end of the century (IPCC, 2014), and if temperature plays a role in the sex selection of tortoises (Ihlow et al, 2012), then tortoise populations may experience a severe imbalance between males and females in the future.
The Giant tortoises have been re-introduced on a few of the Seychelles including: Frégate, North, and Cousine. Unfortunately, residents and property owners of Silhouette Island refused to have wild tortoises roam free on the island, consequently the tortoises had to be moved to neighbouring islands of North, Cousine, and Frégate (Gerlach). Furthermore, North refused to accept all of the refugee tortoises and so Frégate was given the majority of the tortoises. Consequently, one of the greatest threats to the tortoises throughout the Seychelles appears to be non-conservation minded landowners resulting in extirpation and removal of the tortoises. Luckily, the tortoise protection program on Frégate was developed to help preserve the tortoises as a tourist attraction. Although this solution may not last a millennia, in light of climate change, human managed tortoise breeding programs that are accessible on islands with resorts targeted towards eco-tourists may actually be the best option for the tortoises given that rapid changes may soon occur (Gerlach et al, 2013). In this case, the breeding programs may be better funded than otherwise, and the resorts have an active interest in acting as stewards of the island.