Jesse, W.A.M.

Human land use promotes the abundance and diversity of exotic species on caribbean islands

Human land use causes major changes in species abundance and composition, yet native and exotic species can exhibit different responses to land use change. Native populations generally decline in human‐impacted habitats while exotic species often benefit. In this study, we assessed the effects of human land use on exotic and native reptile diversity, including functional diversity, which relates to the range of habitat use strategies in biotic communities. We surveyed 114 reptile communities from localities that varied in habitat structure and human impact level on two Caribbean islands, and calculated species richness, overall abundance and evenness for every plot. Functional diversity indices were calculated using published trait data, which enabled us to detect signs of trait filtering associated with impacted habitats. Our results show that environmental variation among sampling plots was explained by two PCA ordination axes related to habitat structure (i.e. forest or non‐forest) and human impact level (i.e. addition of man‐made constructions such as roads and buildings). Several diversity indices were significantly correlated with the two PCA axes, but exotic and native species showed opposing responses. Native species reached the highest abundance in forests, while exotic species were absent in this habitat. Human impact was associated with an increase in exotic abundance and species richness, while native species showed no significant associations. Functional diversity was highest in non‐forested environments on both islands, and further increased on St. Martin with the establishment of functionally unique exotic species in non‐forested habitat. Habitat structure, rather than human impact, proved to be an important agent for environmental filtering of traits, causing divergent functional trait values across forested and non‐forested environments. Our results illustrate the importance of considering various elements of land use when studying its impact on species diversity and the establishment and spread of exotic species.

 

Date
2018
Data type
Scientific article
Theme
Research and monitoring
Geographic location
St. Eustatius
St. Maarten

Island biogeography meets the Anthropocene - The first expedition.

Many modern human activities result in environmental problems such as pollution, overfishing and deforestation, which have a considerable impact on our natural world. The biodiversity of tropical islands within the Caribbean Region is especially affected by land-use change and the introduction of exotic species. These human activities modify island biodiversity in two ways: introduced species (initially) increase overall biodiversity, while intensified land-use threatens native and endemic species with extinction. The resulting species community shifts, however, remain unknown. For this reason, the Vrije Universiteit Amsterdam (VU) set up the project Island Biogeography meets the Anthropocene to study how invasive species and land-use changes affect the species communities of the Dutch Caribbean Islands. The project’s first field expedition took place in the summer of 2015. 

 

This news article was published in BioNews 21

BioNews is produced by the Dutch Caribbean Nature Alliance and funded by the Ministry of Economic Affairs.

Date
2016
Data type
Media
Theme
Research and monitoring
Geographic location
St. Eustatius
Author

First Recorded Introduction for the Saba Anole (Anolis sabanus) and an Overview of Introduced Amphibians and Reptiles on St. Eustatius

The Lesser Antillean island of St. Eustatius harbors two native anole species, the large Panther or Statia Bank and the smaller Schwartz’s or Saint Kitts Bank Bush Anole (A. schwartzi; max. SVL 53 mm). No exotic anoles had been reported for the island until a stray individual of the lizards Saba Anole (Anolis sabanus) was discovered in the harbor of Oranjestad, St. Eustatius in April 2016, marking the first recorded introduction of the species. 

 

Date
2016
Data type
Scientific article
Theme
Research and monitoring
Geographic location
St. Eustatius