Assessing the impact of an invasive plant in a Protected Natural Area: Island of Cozumel, Mexico

Minimal impacts of invasive Scaevola taccada on Scaevola plumieri via pollinator competition in Puerto Rico

Introduction

Scaevola taccada and Scaevola plumieri co-occur on shorelines of the Caribbean. Scaevola taccada is introduced in this habitat and directly competes with native dune vegetation, including S. plumieri, a species listed as locally endangered and threatened in Caribbean locations. This study addresses whether the invasive S. taccada also impacts the native S. plumieri indirectly by competing for pollinators and represents the first comparative study of insect visitation between these species.

Methods

Insect visitation rates were measured at sites where species co-occur and where only the native occurs. Where species cooccur, insect visitors were captured, identified and analyzed for the pollen they carry. Pollen found on open-pollinated flowers was analyzed to assess pollen movement between the two species. We also compared floral nectar from each species by measuring volume, sugar content, and presence and proportions of amine group containing constituents (AGCCs).

Results

Our results demonstrate that both species share insect visitors providing the context for possible pollinator competition, yet significant differences in visitation frequency were not found. We found evidence of asymmetrical heterospecific pollen deposition in the native species, suggesting a possible reproductive impact. Insect visitation rates for the native were not significantly different between invaded and uninvaded sites, suggesting that the invasive S. taccada does not limit pollinator visits to S. plumieri. Comparisons of nectar rewards from the invasive and the native reveal similar volumes and sugar concentrations, but significant differences in some amine group containing constituents that may enhance pollinator attraction.

Conclusion

Our analysis finds no evidence for pollination competition and therefore S. taccada's main impacts on S. plumieri are through competitive displacement and possibly through reproductive impacts as a consequence of heterospecific pollen deposition.

Alien and Potentially Invasive Plants in Four Lagoons on the Island of Cozumel, Mexico

The expansion of alien invasive species is a worldwide threat that affects most ecosystems. Islands and freshwater ecosystems are among the most vulnerable to species invasion, resulting in reduced biodiversity. In this study, we aimed to explore the floristic composition of the aquatic vegetation in four lagoons in southeastern Cozumel and assess the occurrence and abundance of alien and potentially invasive plants. We found a total of 43 aquatic or underwater herbaceous species that are subject to periodic flooding. Cluster analyses grouped the lagoons into two groups according to their floristic composition. The results demonstrate that alien and potentially invasive plants were dominant in 3 of the 4 lagoons, representing from 7 to 43% of the species. Six of these species were notably abundant, especially in three lagoons. Further, 2 species are considered among the 100 worst invasive species worldwide, although their abundance in Mexico remains relatively reduced. Five alien and potentially invasive species are terrestrial and grow on the shore of the lagoons, while one is aquatic. Urgent control and management actions are necessary. These should include (a) early detection and surveillance to determine if the alien species found behave as invasives; (b) understanding the relevance of invasive species; (c) preventing and intercepting; and (d) control and management. Habitat restoration, adequate legislation, collaboration between stakeholders, and raising awareness of the dangers of releasing or cultivating invasive species in the wild are also necessary.

An Assessment of the Financial Feasibility of an OTEC Ecopark: A Case Study at Cozumel Island

The aim of this article is to show how an OTEC Ecopark could provide comprehensive, sustainable, and quality products that satisfy the diverse needs of coastal communities in Mexico. An offshore 60 MW hybrid Ocean Thermal Energy Conversion (OTEC) plant is proposed, which will provide products that will not only fulfill the water, energy, and food needs of the coastal communities, but also energize the local blue economy. An assessment of the financial feasibility of the plant as well as a comparative analysis against other forms of energy generation was carried out. The methodology section includes a market description, literature review for the technical design, methods for mitigating socio-environmental risks, and an analysis of operational risks. To determine financial feasibility, the CAPEX, OPEX and annual revenue, including the sale of CELs and carbon credits, were evaluated. The Internal Rate of Return suggests that the system would pay for itself in year 5 of the system’s 30-year life. The methodology used for this case study, with site-specific adaptations, can be applied to other coastal communities across the globe.