Functional responses of mangrove fauna to forest degradation

Abstract

Structural degradation of mangroves through the partial removal of trees is globally pervasive and likely to affect ecological functioning, including habitat provisioning for biodiversity. Biodiversity responses will depend on the severity of degradation, yet few studies have contraste and quantified several degradation states. Addressing this knowledge gap, we sampled faunal diversity across a range of mangrove forests in southern Kenya. Canopy cover was the strongest predictor of faunal responses among forest structural variables. Faunal abundance, species richness and biodiversity all decreased with reduction in canopy cover, and taxonomic and functional composition changed. The trophic diversity of crabs peaked at intermediate canopy cover, with degraded habitats having more generalist species and fewer specialists. Functional redundancy was unaffected by canopy thinning. The decline in functional diversity and richness of brachyuran crabs with canopy cover implies that resource-use efficiency weakens with increasing degradation. Our results are indicative of significant alterations to forest functioning with degradation, because epibenthic fauna are important regulators of mangrove ecosystem processes, including nutrient cycling and carbon.

Sustainability level of mangrove forest management based on RAP-MForest approach in Pancer Cengkrong, Trenggalek District, Indonesia

“…It is because mangrove areas provide suitable habitats for fauna to thrive, such as breeding grounds and foraging areas (Zakaria and Rajpar 2015). For instance, canopy cover depletion could negatively impact the crab diversity in a mangrove forest in southern Kenya (Barbanera et al 2022). Another major sensitive attribute is mangrove land pressure.…”

A systematic review of mangrove restoration studies in Southeast Asia: Challenges and opportunities for the United Nation’s Decade on Ecosystem Restoration

“…The shifts in species composition and dominant species at different forest developmental stages are important to assess linkages between restored mangroves and faunal composition/biodiversity. Similarly, such linkages can be used to establish restoration indicators and eventually be used to infer progress/success (Salmo et al, 2017;Barbanera et al, 2022). Beyond mangrove ecosystems, there is a need to expand and consider connectivity studies and include equally important but less studied taxa (i.e., microorganisms, wildlife fauna).…”

“…We acknowledge that vegetation metrics are relatively easier to measure and reflect the traits that recover faster (Cadier et al, 2020;Gatt et al, 2022). However, relating these metrics to ecological functioning (e.g., habitat provisioning for biodiversity) will be more strategic to quantify the effectiveness (or ineffectiveness) of restoration (Ulfa et al, 2018;Barbanera et al, 2022). Aside from vegetation metrics, we also recommend the comparative assessment on biodiversity and ecosystem services among intact, disturbed, and restored mangroves to provide information on restoration trajectory patterns, including species that are effectively restored.…”