non-native species

The Pros and Cons of non-native Seagrass Explosive Expansion

A new study from the Caribbean Netherlands Science Institute and Utrecht University investigated the sediment stabilizing ability of non-native seagrass species Halophila stipulacea, found off the coast of St. Eustatius.  This new fast-growing seagrass has rapidly outpaced native species, leaving many to wonder if its explosive growth will be to the benefit or detriment to the island.

Halophila stipulacea growing into a sand patch. Photo credit: Francine M. van Hee

From anchoring sediments to creating fields of foraging and nursery areas, seagrass meadows play an important role in near shore environments.  Alarmingly, research from St. Eustatius has revealed that the seagrass meadows which once encompassed the entire island are now limited to a small area along the northern shelf. Furthermore, where native species such as turtle grass (Thalassia testudinum) and manatee grass (Syringodium filiforme) have disappeared the non-native species Halophila stipulacea has rapidly spread.

A new study conducted by the Caribbean Netherlands Science Institute and Utrecht University worked to explore the impacts of this population shift.  Namely, the study hoped to determine if this new species could stabilize sediments and help prevent coastal erosion as effectively as native species historically found in this area.

Sand Stability

After 14 weeks, researchers found that sediment within the H. stipulacea meadow had eroded, but this was mostly within the surface sediment layer.  The subsurface layer, however, was believed to be more stable due to the root and rhizome system of the seagrass and saw overall smaller variances when compared to bare sand areas, even during more extreme weather conditions.  Overall, there was less resuspension of sediment in non-native seagrass patches and more long-term sediment level stability when compared to open sand areas.

Habitat Forming

Seagrass meadow with sponge at Double Wreck. Photo credit: Francine M. van Hee

In addition to stabilizing sediments, this new habitat was found to support diverse invertebrate and fish populations.  More specifically, H. stipulacea seems to be popular among filter feeders such as sponges and bivalves, which then in-turn lures in predatory fish, improving overall biodiversity within the area.  Furthermore, since seagrass tends to grow adjacent to coral reefs, algae eating fish which are attracted to the seagrass then work to clean the neighboring corals. Finally, limited resuspension of the sediment coupled with the high update rates of nutrients by seagrass also means clearer waters for the neighboring corals

Implications

Although perhaps not as efficient as native seagrasses, the non-native seagrass H. stipulacea does appear to have some advantages.  Its fast-growing nature means that it can recover more rapidly after extreme storm events than native species. Its rapid expansion could help counter the massive seagrass losses seen around the island, contributing to more sand stability and improved habitat for a wide variety of marine life.

To learn more, the full report can be found on the Dutch Caribbean Biodiversity Database using the link below.

More info in the Dutch Caribbean Biodiversity Database

 

 

Published in BioNews 58.

 

Date
2022
Data type
Media
Theme
Research and monitoring
Geographic location
St. Eustatius
Author

Vegetation changes on the island of Saba, effects of huricanes, people and non-native species

Powerpoint presentation with findings of a 4 week vegetation fieldvisit on Saba:

  • what is vegetation (research)?
  • historic findings (1956 and 1999)
  • current findings (49 repeated plots, 28 additional plots)
  • preliminary results for different zonation belts
    • elfin forest (highest zone)
    • elephants ears scrub
    • transitional forest
    • dry tropical forest
    • grasslands, shrubland and coastal cliffs (lower zone)
  • conclusions
    • elfin forest far from 'original'
    • zonation 2,3 and 4: no big changes, some expansion of elephant ears, more forest succesion resulting in more closed vegetation and poorer in bio-diversity
    • invasive species are more abundant in the lower zone: coralita, rubber vine,'india grass' and others
Date
2020
Data type
Other resources
Theme
Research and monitoring
Geographic location
Saba
Author
Image

Caribbean island launches plan to remove invasive rats and goats

The remote Caribbean island of Redonda, part of Antigua and Barbuda, is home to numerous species of plants and animals found nowhere else on earth. It is also home to invasive black rats and non-native goats that are wiping out the island’s native, rare wildlife, conservationists say.

To help the island’s flora and fauna, the Government of Antigua and Barbuda is now initiating a plan to remove all goats and rats from the island. The Redonda Restoration Program program has been formed by the Antigua & Barbuda Government and the Environmental Awareness Group (EAG) in collaboration with organizations like Fauna & Flora International, British Mountaineering Council, Island Conservation and Wildlife Management International Ltd.

Date
2016
Data type
Media
Theme
Education and outreach
Research and monitoring
Author

Harmful invasive alien species (IAS) in the Caribbean Netherlands

Following climate change, IAS are recognised as the second-most serious long-term threat to island ecology, worldwide. Of all IAS issues, by far the most serious is the problem of roaming livestock. On most islands this concerns the eubiquitous domestic goat. 

In addition to major inventories of invasive species (see the first 4 reports below) and the development of a joint strategy, as part of the Wageningen BO research program, IMARES has also led the way to several pilot-scale interventions, in close cooperation with island partners. Current studies include work to document the positive effect of feral cat control on survival of endangered ground-nesting seabirds in Saba, control and eradication of the Giant African Landsnail on Statia and control of goat grazing inside the Washington Slagbaai park in Bonaire. Within the European Netherlands, IAS are also recognized as a key scourge to both nature and economy and in 2015 stringent new legislation was implemented not only in the Netherlands, but throughout the EU. See below, for a full listing of IMARES recent work in this area of concern.

The problem of roaming livestock is particularly acute in the Caribbean Netherlands. It is a major impediment to agricultural development and nature conservation on St. Eustatius, as it also typically is on other islands in the region. In support of a government-led culling program, we here conducted a baseline study of livestock abundance and distribution on the island in the final quarter of 2013. In doing so we provide the first quantitative assessment of livestock densities ever in the Dutch Caribbean.

Date
2016
Data type
Other resources
Theme
Education and outreach
Research and monitoring
Geographic location
Aruba
Bonaire
Curacao
Saba
Saba bank
St. Eustatius
St. Maarten
Author

Feral goat eradications on islands.

Abstract: Introduced mammals are major drivers of extinction. Feral goats (Capra hircus) are particularly devastating to island ecosystems, causing direct and indirect impacts through overgrazing, which often results in ecosystem degradation and biodiversity loss. Removing goat populations from islands is a powerful conservation tool to prevent extinctions and restore ecosystems. Goats have been eradicated successfully from 120 islands worldwide. With newly developed technology and techniques, island size is perhaps no longer a limiting factor in the successful removal of introduced goat populations. Furthermore, the use of global positioning systems, geographic information systems, aerial hunting by helicopter, specialized hunting dogs, and Judas goats has dramatically increased efficiency and significantly reduced the duration of eradication campaigns. Intensive monitoring programs are also critical for successful eradications. Because of the presence of humans with domestic goat populations on large islands, future island conservation actions will require eradication programs that involve local island inhabitants in a collaborative approach with biologists, sociologists, and educators. Given the clear biodiversity benefits, introduced goat populations should be routinely removed from islands.

Date
2005
Data type
Scientific article
Theme
Research and monitoring

The Role of Tourism and Recreation in the Spread of Non-Native Species: A Systematic Review and Meta-Analysis

Managing the pathways by which non-native species are introduced and spread is consid- ered the most effective way of preventing species invasions. Tourism and outdoor recrea- tion involve the frequent congregation of people, vehicles and vessels from geographically diverse areas. They are therefore perceived to be major pathways for the movement of non- native species, and ones that will become increasingly important with the continued growth of these sectors. However, a global assessment of the relationship between tourism activi- ties and the introduction of non-native species–particularly in freshwater and marine envi- ronments–is lacking. We conducted a systematic review and meta-analysis to determine the impact of tourism and outdoor recreation on non-native species in terrestrial, marine and freshwater environments. Our results provide quantitative evidence that the abundance and richness of non-native species are significantly higher in sites where tourist activities take place than in control sites. The pattern was consistent across terrestrial, freshwater and marine environments; across a variety of vectors (e.g. horses, hikers, yachts); and across a range of taxonomic groups. These results highlight the need for widespread biose- curity interventions to prevent the inadvertent introduction of invasive non-native species (INNS) as the tourism and outdoor recreation sectors grow. 

Date
2015
Data type
Scientific article
Theme
Research and monitoring
Journal