herpetology

Biodiversity in a globalized world: The journey of exotic species from origin to impact

Abstract

Invasive alien species (IAS) are species that have been introduced to locations outside of their distributional range via human transport. In their novel exotic range, these species reach quickly reproduce and/or spread, hence the connotation “invasive”. Examples of well-known problematic IAS include tropical mosquitos bearing diseases such as Zika virus, predatory animals such as the lionfish or black rats, and plants blanketing anything they encounter. IAS are considered to be a major threat to biodiversity with extensive societal and economic consequences. However, invasive species do not become invasive overnight; invasion is the final and most detrimental stage of a much longer process. The aim of this thesis was to disentangle the natural and anthropogenic causes and consequences of species invasion by following exotic species from their origin to their impact. This thesis is structured along the different stages of species invasion and answers three overall research questions: Where do exotic species come from?; Where do exotic species end up?; What are the consequences of exotic species invasion?. The first question Where do exotic species come from? is answered in Chapter 2 that showed that exotic species and species endangered with extinction inhabit the same locations but contrast each other in terms of their traits. Both groups are overrepresented on human-impacted oceanic islands. The question: Where do exotic species end up? is answered by Chapters 3-5. In this section I conclude that within islands invaded by several exotic reptiles, these species are found almost exclusively in human-impacted environments with open or shrubby vegetation. Conversely, native species reach highest abundances in forest sites (Chapter 3). Hurricanes severely alter available habitats for reptiles (Chapter 4). Native species abundances of the lizard genus Anolis decreased with increasing levels of hurricane-induced habitat change, especially on St. Martin that was severely hit by the hurricanes Irma and Maria. Exotic species varied in their response, but we detected exotic species in previously uninvaded forests. That species from small, less populated islands also get introduced was demonstrated by the first published record of an exotic Saban anole (A. sabanus) found in the harbor of St. Eustatius (Chapter 5). This chapter serves as proof of concept that shipping is an important vector for exotic reptiles. The question What are the consequences of species invasion? is answered in Chapters 6-8, featuring the extensive invasion of the Coralita vine (A. leptopus) on St. Eustatius, impacting approximately one-third of this island. Coralita significantly alters the species composition of arthropod communities on St. Eustatius. After invasion the unique communities in urban and natural sites become homogenized to the point where they become undistinguishable (Chapter 6). The plant also has societal consequences through the reduced availability of ecosystem services (ES) (Chapter 7-8). Through a novel methodology we were able to provide estimates of ES value loss to the economy of St. Eustatius (Chapter 7-8), amounting to 42.000 dollar per year in case 3% of the island would be dominantly covered by the plant, rising to 640.000 dollar per year in case the entire range of Coralita would reach dominant coverage. We estimate that it requires a total investment of 12,7 million dollars (12% of GDP) to revert back from the worst case scenario to a Coralita-free situation. In general based on the work in this thesis I can conclude that the process of species invasion is 1) to some extent predictable at its various stages; 2) an important, independent driver of change augmented by several natural and anthropogenic factors; and 3) has major consequences for biological systems as well as human welfare and wellbeing through invasion-induced changes in ecosystem services.

 

 

https://research.vu.nl/en/publications/biodiversity-in-a-globalized-worl...

 

Date
2022
Data type
Research report
Theme
Research and monitoring
Report number
PhD Thesis
Geographic location
Saba
St. Eustatius
St. Maarten

Fieldguide to the Amphibians and Reptiles of Aruba, Curaçao and Bonaire

While translating the Dutch version of "de Amfibieen en Reptielen van Aruba, Curaçao en Bonaire" into English, I was forced to go through the entire text one more time, line by line. Thus it was inevitable that I ended up editing the text somewhat and adding to it as well. Since an English manuscript was now available, several people who had not been consulted previously could now give their comments, which have been incorporated in the English version. Thus the English translation is not a literal transcription of the Dutch version, although the differences between both versions are relatively minor. The islands of Aruba, Curaçao and Bonaire form part of a larger archipelago of islands along the Venezuelan coast. This archipelago includes all the islands from Los Monjes in the West to La Blanquilla in the East. The herpetofauna of the islands of Aruba, Curaçao and Bonaire should be viewed from this somewhat larger perspective. For this reason there are many references to the Venezuelan islands. Faunistic zones often transcend national borders. In this respect I have followed wagenaar hummelinck who in 1940 published the first general treatise of the herperofauna of this archipelago. My field guide is in large part based on this early work of wagenaar hummelinck (†).

This field guide is certainly not intended as a taxonomic work. Most guide books use slightly different classifications, sometimes all these differences can be quite exasperating. The latest classification is not necessarily the best, and some of the newer ideas have not gained general acceptance. In this English version the sub-species Leptodeira annulata bakeri and Crotalus durissus unicolor from the Dutch edition have been upgraded to full species status, in accordance with the prevailing taxonomic trends. I have simply tried to follow what seemed "the roads most traveled" and in many cases have indicated that other classifications also exist. In doing this I have certainly developed my own preferences, often siding with the "lumpers'', sometimes with the "splitters". I fully realize however that I do not have the expertise to make these kinds of taxonomic judgments, which are better left to others. It is however important to convey to the general public the idea that taxonomy has a subjective element and that taxonomy is not a static structure, but something that can change on the basis of new evidence or new interpretations. The field guide is also intended as a review summarizing available information on the herpetofauna of these islands. Local information on customs, beliefs and origins of local names has been included. The list of literature, cites many general works but is also intended to serve as a bibliography of the herpetofauna of the islands of Aruba, Curaçao and Bonaire. The sea turtles have not been included. In 1995 I published "De Schildpadden van Curaçao en Bonaire" (The turtles of Curaçao and Bonaire). This book was primarily intended for local use, one of its primary aims was to generate support for sea turtle protection. Since many books on sea turtles in the region already exist, there is no special need to translate this book into English.

Author's note, November 2017: This guide is somewhat outdated; some scientific names have changed, new invasive species have established themselves, at least on Curaçao, and of course new literature has appeared. Actually, a new edition is needed.

Date
2005
Data type
Book
Theme
Research and monitoring
Geographic location
Aruba
Bonaire
Curacao
Author