Threatened Mangroves in the Anthropocene: Habitat Fragmentation in Urban Coastalscapes of Pelliciera spp. (Tetrameristaceae) in Northern South America

Abstract

Mangroves are fragmented habitats thriving in human-dominated coastalscapes worldwide. They provide refuge to threatened plant species, such as the Neotropical Piñuelo Mangrove (formerly the monotypic Pelliciera genus, recently split into two species: P. rhizophorae and P. benthamii). However, little is known about the relationship between urbanization and the spatial configuration of mangrove habitat and how it would drive ecological and evolutionary changes in the small populations of Pelliciera spp. We used open data (e.g., land cover, mangrove cover) for 107 locations of Pelliciera spp. in Colombia (extant populations) to assess coastalscape structure and urbanization. We described coastalscape composition dynamics (for 2000 and 2010) and mangrove habitat configuration along a human-domination gradient, using landscape metrics. We computed an urban index to compare urbanization intensity among the study areas along the Caribbean coast and compared coastalscape structure and mangrove spatial metrics between basins (Caribbean and Pacific). The proportion of artificial surfaces was greater in the Caribbean than in the Pacific, but no temporal difference was found. The Caribbean basin exhibited a greater Urban Index, particularly in Cartagena and Urabá. Mangrove fragmentation was also greater in the Caribbean and it was influenced by the degree of urbanization. Mangrove area and core area were smaller in the Caribbean than in the Pacific, while cohesion was significantly lower in Cartagena than in other urban areas of the Caribbean. We propose a conceptual eco-evolutionary framework for linking mangrove patch reduction and isolation to demographic variables of Pelliciera spp. Edge effects are expected to affect birth and mortality rates in small patches. Small patches and small effective populations are expected to be more sensitive to novel biotic interactions, extreme weather, and gradual climate change. Isolation will also influence both emigration and immigration rates of propagules. We propose: (1) Assessing the conservation status of the two species, (2) setting monitoring programs of their populations of Pelliciera spp. and their surrounding coastalscapes (particularly in the Caribbean, (3) declaring protected areas, in wild and urban settings, to reduce mangrove fragmentation and urbanization.

Cascading effects of climate change on recreational marine flats fishes and fisheries

“…A disproportionate loss or shift of habitats, particularly in coastal flats systems, may jeopardize the structure and function of entire coastal ecosystems, including coastal flats and their inhabitants. Physical damage to flats habitats reducing patch sizes could also increase sensitivity to other disturbances such as extreme weather conditions and sea level rise (Blanco-Libreros and Ramirez-Ruiz 2021 ), both of which are resulting because of climate change.…”

Taxon cycles in Neotropical mangroves

“…P. rhizophorae has been listed as “Vulnerable” – that is, under a high risk of extinction in the wild due to its small (500-2000 km 2 ) and fragmented distribution area – in the IUCN Red List of Threatened Species (Polidoro et al, 2010; Blanco et al, 2012; Bhowmik et al, 2022). Urban expansion has been recognized as a major threat for Pelliciera populations, which are being heavily fragmented and threatened by habitat loss (Blanco-Libreros & Ramírez-Ruiz, 2021). From a biogeographical perspective, the available evidence suggests that, rather than shrinking the distribution area of Pelliciera as a whole, human activities have caused its severe fragmentation, which affects population viability and increases the sensitivity to extreme events and global warming (Blanco-Libreros & Ramírez-Ruiz, 2021).…”

“…Urban expansion has been recognized as a major threat for Pelliciera populations, which are being heavily fragmented and threatened by habitat loss (Blanco-Libreros & Ramírez-Ruiz, 2021). From a biogeographical perspective, the available evidence suggests that, rather than shrinking the distribution area of Pelliciera as a whole, human activities have caused its severe fragmentation, which affects population viability and increases the sensitivity to extreme events and global warming (Blanco-Libreros & Ramírez-Ruiz, 2021). In the context of the taxon cycle, it could be asked whether the total extinction of Pelliciera is approaching and how human activities could contribute to accelerating this end.…”

Eocene/Oligocene global disruption and the revolution of Caribbean mangroves

“…P. rhizophorae has been listed as Vulnerable -that is, under a high risk of extinction in the wild due to its small (500-2000 km 2 ) and fragmented distribution area -on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species (Polidoro et al, 2010;Blanco et al, 2012;Bhowmik et al, 2022). Urban expansion has been recognized as a major threat for Pelliciera populations, which are being heavily fragmented and threatened by habitat loss (Blanco-Libreros & Ramírez-Ruiz, 2021). Good regeneration prospects have been reported for some extant Pelliciera populations that would encourage eventual restoration and reforestation actions (Gross et al, 2014;Alvarez-León, 2019;Madrid et al, 2019).…”

“…However, urgent conservation actions, such as the creation of protected areas to control urban expansion, are still needed. From a biogeographical perspective, the available evidence suggests that, rather than shrinking the distribution area of Pelliciera as a whole, human activities have caused its severe fragmentation, which affects population viability and increases sensitivity to extreme events and global warming (Blanco-Libreros & Ramírez-Ruiz, 2021). To extent to which prehistoric societies would have affected the distribution area of Pelliciera remains unknown due to the scarcity of paleoecological records.…”