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.

A Review of Disturbances to the Ecosystems of the Mexican Caribbean, Their Causes and Consequences

In a relatively short timescale (less than 50 years), urbanization has caused many anthropogenic disturbances that have affected ecosystem health and, directly or indirectly, quality of life for the local human population. Global disturbances, such as climate change, can also have a substantial, overarching impact on ecosystems. In this scenario, natural disturbances, previously considered an integral part of ecosystem dynamics, can now cause irreversible change to the state of ecosystems, and at the same time, negatively impact social and economic systems. The objective of this study was to identify ecosystem disturbances at a site of interest to recommend strategies to improve coastal zone management. We chose the Mexican Caribbean as a case study, because its biological and cultural complexity render it an interesting location from a coastal management point of view. The PRISMA framework was used to conduct a systematic literature review to identify the ecosystem disturbances that affect this area, as well as the main causes and consequences of these disturbances. Additionally, we discuss how disturbances and their impacts, as screened through PRISMA, can be incorporated into a coastal zone management framework. Results need to consider the limitations associated with using this technique e.g., the degree of impact from a current disturbance may vary from that reported in an earlier publication. Despite its limitations, we believe that this methodology proves useful for identifying key ecosystem disturbances and their consequences, providing a useful tool for identifying appropriate actions to inform coastal zone management plans.

Complex genetic patterns and distribution limits mediated by native congeners of the worldwide invasive red-eared slider turtle

Non-native (invasive) species offer a unique opportunity to study the geographic distribution and range limits of species, wherein the evolutionary change driven by interspecific interactions between native and non-native closely related species is a key component. The red-eared slider turtle, Trachemys scripta elegans (TSE), has been introduced and successfully established worldwide. It can coexist with its native congeners T. cataspila, T. venusta and T. taylori in Mexico. We performed comprehensive fieldwork, executed a battery of genetic analyses and applied a novel species distribution modeling approach to evaluate their historical lineage relationships and contemporary population genetic patterns. Our findings support the historical common ancestry between native TSE and non-native (TSE_alien ), while also highlighting the genetic differentiation of the exotic lineage. Genetic patterns are associated with their range size/endemism gradient, the microendemic T. taylori showed significant reduced genetic diversity and high differentiation, whereas TSE_alien showed the highest diversity and signals of population size expansion. Counter to our expectations, lower naturally occurring distribution overlap and little admixture patterns were found between TSE and its congeners, exhibiting reduced gene flow and clear genetic separation across neighboring species despite having zones of contact. We demonstrate that these native Trachemys species have distinct climatic niche suitability, likely preventing establishment of and displacement by the TSE_alien . Moreover, we found major niche overlap between TSE_alien and native species worldwide, supporting our prediction that sites with closer ecological optima to the invasive species have higher establishment risk than those that are closer to the niche-center of the native species.