ecology

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

Ecologyand Microeconomics as "Joint Products": The Bonaire Marine Park in the Caribbean

FOREWORD

Many countries are strugglingwith the task of meeting ecological and economicgoals associated with the establishment and management of protected areas. Sometimesthe attempt to meet both goals leads to conflict. For land based parks the problems are well-known: establishment of protected areas often results in depriving nearby residents of important economicbenefits from use of the flora and fauna containedin the newly protected area.

Marine parks, especiallythose found in the Caribbean,'offeropportunitiesfor both resource conservation and generationof economic benefits. The establishment of marine parks helps protect fragile coral reefs and their associated fish and plant populations. Maxine-based tourism, includingboth SCUBA divers and yachting, are also important economic activities that do not have to be in conflict with conservation and protection of the marine ecosystem.

This Dissemination Note explores these issues in the case of the Bonaire Marine Park in the Netherlands Antilles. It examinesthe impact of tourismand recreational use on the marine ecosystem, and the economicimportance of tourism and recreation to the island economy. The study is a multi-disciplinary effort as the authors include both economists (Dixon and Scura) and an ecologist (van't Hof). The paper presents an analytical approach to understandingthe dynamicsof diver impact on the Park's reefs, and describes management alternativesthat can allow increased diver use of the Park's coral reefs without exceedinga damage-inducing "stress threshold" level.

Since divers both causes stress on the marine ecosystem,and generates the revenues that pay for improved marine conservationand management,at certain levels of use the ecological and economic benefitscan be considered as a type of "joint product" of recreational diver use. Beyond the 'stress threshold" level, however, increased use leads to direct tradeoffs between marine conservationand generation of economicreturns, e.g., increasing levels of direct use result in increased income (at least in the short run), but may damage the reefs and the fish population, thereby hurting the very thing that attracted visitors in the first place.

The authors estimate that the critical stress threshold level is between 4000-6000 dives per site per year, an intensity of use that is already being exceeded in certain areas. They then suggest measures that can help increase the effectivecarrying capacity of the Park (e.g. allowing more divers into the water while minimizing negativeimpacts) and increasing the generation of income, both to help pay for park management, and to keep a larger share of economic benefits within the Bonairean economy. It shouldbe possible, therefore, to meet both ecological and economic goals.

Like other papers in this series, this DisseminationNote has not been subject to either substantialintemal review or editing. Therefore the findings,interpretations, and conclusionsexpressed are entirely those of the authors and shouldnot be attributed to the World Bank, members of its Board of Executive Directors, or the countries they represent.

Date
1993
Data type
Research report
Theme
Research and monitoring
Geographic location
Bonaire

Fish poop: an underappreciated food source for coral reef fishes?

A new study by researchers from the University of Texas and California Polytechnic State University documented herbivorous fishes feeding on fish fecal pellets off the coast of Bonaire.  This has never been recorded in the Caribbean before and provides a deeper understanding of nutrient recycling and insight into the diverse diets of fishes who work to keep the local coral reefs healthy.

Blue parrotfish (Scarus coeruleus). Photo credit: Marion Haarsma

Coral reefs are one of the most diverse ecosystems on the planet, but they are also limited in nutrients. So, nutrient recycling is a vital part of supporting such reef organisms and their biodiversity. Organisms can’t process all the nutrients from the food they eat, so some of these nutrients come out in their poop. A new study documented a unique upcycling technique, previously unknown within the Caribbean, herbivorous fish feeding on fish feces.

Parrotfishes and surgeonfishes are often praised as the great caretakers of coral reefs, feeding on reef algae and keeping overgrowth in check, which indirectly promotes healthy coral recruitment and growth.  Although it was previously known that Caribbean parrotfishes and surgeonfishes also fed off other food sources, such as cyanobacteria, sponges, and even corals themselves, a recent study added fish feces to this list.

The Study

This collaborative effort was co-led by Hannah Rempel, a Ph.D. student from University of Texas Marine Science Institute and Abigail Siebert, a former undergraduate student from California Polytechnic State University. They studied the foraging rates of parrotfishes and surgeonfishes on fish fecal matter. Because they found that over 99% of feces they consumed were from the Brown Chromis (Chromis multilineata), a plankton eating fish, they also observed Brown Chromis feces to see what other reef fish ate them and studied the nutritional value of these feces. The study was conducted in 2019 between June and September, across six dive sites along the western shores of Bonaire.  This research is the first of its kind within the Caribbean and paves the way for continued exploration into the topic.

Fecal pellet. Photo credit: Hannah Rempel

The Results

Throughout this study, researchers documented that almost 85% of the observed fecal pellets were ingested by fish with over 90% consumed by parrotfish and surgeonfishes alone. “Compared to algae, these fecal pellets are rich in a number of important micronutrients. Our findings suggest they may be an important nutritional supplement in the diets of these fishes” stated Rempel. Taking a closer look at the fecal matter itself, researchers found that these pellets had higher values of proteins, carbohydrates, total calories, and important micronutrients when compared to most algae.  Therefore, consuming fecal matter may play an important role in nutrient transfer within the marine environment.

Future Research

Understanding the intricate dynamics within coral reefs provides information management authorities need to safeguard these environments more effectively. These results highlight the importance of the consumption of fecal matter in upcycling micronutrients, although there is still much to be learned about the nutritional content of other food sources, such as algae mats, cyanobacteria, sponges and corals.  Fish feces may play a vital role in nutrient supply within the reef environment, emphasizing the need for further insight into this topic moving forward.

For more information you can find the full report on the DCBD by using the link below.

More info in the Dutch Caribbean Biodiversity Database

 

 

Published in BioNews 53

Date
2022
Data type
Media
Theme
Research and monitoring
Geographic location
Bonaire
Author

POPULATION ESTIMATE, NATURAL HISTORY AND CONSERVATION OF THE MELANISTIC IGUANA IGUANA POPULATION ON SABA, CARIBBEAN NETHERLANDS

Abstract.– Intraspecific diversity is among the most important biological variables, although still poorly understood for most species. Iguana iguana is a Neotropical lizard known from Central and South America, including from numerous Caribbean islands. Despite the presence of native melanistic I. iguana populations in the Lesser Antilles, these have received surprisingly little research attention. Here we assessed population size, distribution, degree of melanism, and additional morphological and natural history characteristics for the melanistic iguanas of Saba, Caribbean Netherlands based on a one-month fieldwork visit. Using Distance sampling from a 38- transect dataset we estimate the population size at 8233 ±2205 iguanas. Iguanas mainly occurred on the southern and eastern sides of the island, between 180-390 m (max altitude 530 m), with highest densities both in residential and certain natural areas. Historically, iguanas were relatively more common at higher altitudes, probably due to more extensive forest clearing for agricultural reasons. No relationship was found between the degree of melanism and elevation, and few animals were completely melanistic. Furthermore, we found that body-ratio data collection through photographs is biased and requires physical measuring instead. Although the population size appears larger than previously surmised, the limited nesting sites and extremely low presence of juvenile and hatchling iguanas (2.4%), is similarly worrying as the situation for I. delicatissima on neighboring St. Eustatius. The island’s feral cat and large goat population are suspected to impact nest site quality, nest success, and hatchling survival. These aspects require urgent future research to guide necessary conservation management.

Date
2022
Data type
Scientific article
Theme
Research and monitoring
Journal
Geographic location
Saba

Final report: Corallita Pilot Project, Study on the ecology and possible control methods of the invasive plant species Antigonon leptopus (Corallita or Mexican Creeper)

This one-year pilot project aims to provide an insight in the ecology of Antigonon leptopus (Corallita) an invasive vine, which is overgrowing the native vegetation (Photo 1). This pilot project is just a first step in controlling the Antigonon leptopus. This research was done on a small scale and under controlled circumstances. Our ideas are just for small scale use in town but also to eradicate ‘hotspots’ to prevent further spreading especially near the National Parks. The government with STENAPA as a consultant should take further actions to continue this project and put it as a high priority. The first step was made and we hope this will contribute in containing the species and monitoring the species closely. More research on the life circle and possible natural enemies and its sensitivity for herbicides should be done in order to start a larger scale eradication campaign. The project does not stand on its own, the vine contributes in the prevention of soil erosion on the island. A full size project including replanting/reforestation with native species and renewed agricultural activities should be set up for the long term.

Objectives

  • The primary research aim is to reduce and control the growth of Corallita on St. Eustatius and to prevent the species from invading the national parks. In order to achieve this, it is necessary.
  • To gather information about the ecology of the species, such as its life cycle, dispersal, germination capacity, use of the species by animals etc. • To gather information about how the species will react on different potential control methods.
  • Inform the local community about control methods if usable results are obtained.

Discussion and conclusion

Three weeks after the first treatment at Gallow Bay no regrowth was observed, this means the herbicide does work with smaller concentration (12.5% and 25%) on short term. After six weeks the first regrowth was observed. The tubers are still intact after the first treatment. It is not known how many times the treatment with these concentrations is needed.

In both plots of Sandy Road the plants have regrowth after 7½ weeks. Our observation on 13th January 2007 showed that a lot of Corallita was growing from the border into the plots covering the soil. The treatment did work but probably needed a second treatment if there is regrowth of 30-40cm. Further monitoring of large plots (during one year) is needed to make sure smaller concentrations will kill the plants. Tubers should de dug up and checked on viability. New plots should be selected.

 

 

Date
2007
Data type
Research report
Theme
Research and monitoring
Geographic location
St. Eustatius
Image

Caribbean Bryozoa: Anasca and Ascophora Imperfecta of the inner bays of Curaçao and Bonaire

The present paper deals with the Anasca and Ascophora Imperfecta of the inland bays of Curaçao and Bonaire. Collections were made by P. Wagenaar Hummelinck (1930, 1936/ 37, 1948/49, 1955, 1963/64, 1968, 1970, and 1973) and by the author (1982), and stored in the collections of the Rijksmuseum van Natuurlijke Historie, Leiden. A total of 25 species – almost all occurring in inland bays – are described here and fully illustrated. Six new species are established: Crassimarginatella harmeri, Scrupocellaria curacaoensis, Scrupocellaria carmabi, Scrupocellaria piscaderaensis, Scrupocellaria hildae and Bugula hummelincki. Attention is given to the ecology of the species. The bays have been compared as to species composition in relation to substrate and conditions during collecting.

Date
1986
Data type
Scientific article
Theme
Research and monitoring
Geographic location
Bonaire
Curacao

Flamingos on Bonaire and in Venezuela

Results of a three year study (1975-1978) of Flamingos on Bonaire and in Venezuela, including population size, food availability, migration and nesting patterns.

On Bonaire the numbers of flamingos now do not differ significantly from those found before the Salt Works started. Nevertheless the food situation for the flamingos has deteriorated. The area available to them has been diminished and it seems they prefer the food in Venezuela. They do feed readily in the Salt pans though and there is abundant food available to them once they accept the snails as food item. There are signs however that the predation on Gemma purpurea is too heavy. It is unlikely that the gypsum crust in the higher pans will be removed. The management of the AISCO is however convinced that a biological management is absolutely necessary for the salt production too. It is to be expected that the dumping of fertilizers will enhance the organic production in the salt pans and hence the food supply for the flamingos. As explained there are certain dangers to this fertilizer program too. In changing the flow system the AISCO should take into account the effect of this on the flamingo-population. Also plans for harvesting brine shrimps must be weighed against the needs of the flamingos. Therefore it would be useful if e.g. 4 times a year there would be a control on the biological processes in the salt works. Biologists from the Caribbean Marine Biological Institute (Carmabi) on Curaçao could help out with this, possibly under auspices from the Stinapa, the foundation for nature conservancy in the Netherlands Antilles. It is clear that too much disturbance takes place, especially in the Sanctuary. A stricter guard should be kept to keep possible intruders out. The best solution would be if the government of Bonaire would appoint a special guard for the flamingos, at least for the breeding season. The airport officials should be more aware of their task to keep planes from entering the forbidden area and if a plane would tresspass stern measures should be taken against the pilot. It is highly recommendable to build some kind of observation post from which tourists can have a look at the breeding colony. A telescope (the type in which you have to throw a coin to look) seems to be in the possession of the Bonaire government already. An ideal place to put it would be the house next to the red slavehuts . It would prevent a lot of disappointment for bird-watching tourists, and justify the name of Flamingo island for Bonaire. An operator at the place could serve at the same time as guard for the flamingo-colony.

At the entrance to Lake Goto an oil-terminal has been built, far with little disturbance for the flamingos. Care should be so taken however that by a further expansion of this terminal lake Goto and its shores remain completely untouched. Especially the seapage from sea through the coral debris wall at the entrance of the lake should not be disturbed as this together with the high evaporation maintains the highly salinity environment.

The plantation Slagbaai has recently come into the possession of Stinapa. Plans are ready to open this area to the public and some facilities for visitors will be made. As the flamingos reside in the landlocked bay, and especially near some buildings which will be restored and put into use, care should be taken that the flamingos will not be chased by too eager bird watchers or photographers.

Date
1979
Data type
Research report
Theme
Research and monitoring
Report number
STINAPA Documentation Series, No. 3
Geographic location
Bonaire
Author

Seascape continuity plays an important role in determining patterns of spatial genetic structure in a coral reef fish

Detecting patterns of spatial genetic structure (SGS) can help identify intrinsic and extrinsic barriers to gene flow within metapopulations. For marine organisms such as coral reef fishes, identifying these barriers is critical to predicting evolutionary dynam- ics and demarcating evolutionarily significant units for conservation. In this study, we adopted an alternative hypothesis-testing framework to identify the patterns and pre- dictors of SGS in the Caribbean reef fish Elacatinus lori. First, genetic structure was estimated using nuclear microsatellites and mitochondrial cytochrome b sequences. Next, clustering and network analyses were applied to visualize patterns of SGS. Finally, logistic regressions and linear mixed models were used to identify the predic- tors of SGS. Both sets of markers revealed low global structure: mitochondrial ΦST = 0.12, microsatellite FST = 0.0056. However, there was high variability among pairwise estimates, ranging from no differentiation between sites on contiguous reef (ΦST = 0) to strong differentiation between sites separated by ocean expanses ≥ 20 km (maximum ΦST = 0.65). Genetic clustering and statistical analyses provided additional support for the hypothesis that seascape discontinuity, represented by oceanic breaks between patches of reef habitat, is a key predictor of SGS in E. lori. Notably, the esti- mated patterns and predictors of SGS were consistent between both sets of markers. Combined with previous studies of dispersal in E. lori, these results suggest that the interaction between seascape continuity and the dispersal kernel plays an important role in determining genetic connectivity within metapopulations. 

Date
2014
Data type
Scientific article
Theme
Research and monitoring