Variation in mangrove species diversity across gradients of climate-change-induced environmental conditions and hydrological restoration.

Increasing drought, elevated temperatures, and salinization are significant challenges to reestablishing species in mangrove restoration areas. In this study, we assessed how the diversity of two key mangrove faunal groups, molluscs and brachyuran crustaceans (hereafter referred to as crabs), varies across a gradient of disturbed, restored, and natural (undisturbed) mangroves. We also explored what are the environmental factors driving these variations in ten sites across the southern Gulf of Mexico, one of the global regions with the largest mangrove coverage. A total of 15 species were recorded (10 mollusks and 5 crabs), with higher abundance in natural (612 individuals) than in restored (554 individuals) or degraded (98 individuals) sites. Community structure analyses revealed that certain species were restricted to specific restoration conditions. For example, the crab Minuca vocator was found only in restored sites, while the mollusc Vitta virginea was exclusive to natural sites. In contrast, species like the crab Minuca rapax were present across all site types. Salinity emerged as the primary environmental factor influencing community structure, with disturbed sites exhibiting significantly higher salinity levels than restored and natural sites. All sites were classified as hypersaline, presenting challenges for species that cannot tolerate such conditions. This study provides a valuable baseline for understanding the ecological conditions that influence on the success of mangrove restoration, offering insights on the effects of environmental factors driving species diversity in this ecosystem.