Mangroves are a taxonomically varied group of halophytic (salt-tolerant) shrubs and trees that occur in the space between high and low tides on tropical and subtropical shorelines, a harsh and highly dynamic environment that presents exceptional challenges to the species that inhabit them (Hogarth 2015; Primavera et al. 2018; Spalding et al. 2010; Tomlinson 2016). Mangrove forests are unique ecosystems that occur in the intertidal zones of tropical and subtropical coastlines. Mangrove forests are unique coastal ecosystems that depend on a delicate balance of freshwater and seawater to sustain their health and biodiversity. The influx of freshwater is crucial for reducing salinity levels and providing essential nutrients, while seawater delivers vital minerals and supports tidal flushing, which helps prevent the buildup of toxins. The mechanism by which seawater and freshwater water interact in mangrove ecosystems is complex and involves several factors. One of the key mechanisms by which seawater and freshwater interact in mangrove ecosystems is through the process of tidal inundation (Wolanski et al., 1992). Tidal inundation occurs when seawater flows into mangrove forests during high tides and then recedes during low tides, leaving behind a mixture of seawater and fresh water (Kumbier et al., 2021). This process helps to maintain the salinity levels of the mangrove ecosystem within a range that is tolerable for the growth and survival of mangrove species. Another important mechanism is the exchange of water between the mangrove ecosystem and surrounding freshwater sources, such as creeks, rivers and streams (Bunt et al., 1982). In some cases, freshwater inputs may be the dominant source of water for mangrove ecosystems, while in other cases, seawater may be the dominant source. The balance between freshwater and seawater inputs is critical for maintaining the salinity levels of mangrove ecosystems (Santini et al., 2015).
Generally, mangrove forests worldwide are decreasing at an increasing rate of one to two percent per year, particularly in developing countries, which host 90% of the world's mangrove forests (Duke et al., 2007). Almost one-third of the world's mangrove forests have vanished between 1950 and 2000 (Alongi, 2002). It is estimated that annual mangrove forest loss averaged 0.26–0.66% globally between 2000 and 2012 (Hamilton and Casey, 2016). Studies indicate that these forests respond quickly to short-term environmental changes; thus, in the short term, in addition to being highly vulnerable, they also possess great potential for growth and expansion given suitable environmental conditions or direct and indirect human interventions. For instance, some countries, such as Puerto Rico, Guinea, Bangladesh, Australia, and India, have experienced little change in the extent of mangroves or even witnessed their expansion (FAO 2007; De Boer 2002).
The global extent of mangrove forests is reportedly ~ 15.2 × 106 ha distributed across 55 countries worldwide (Giri et al. 2011; Friess et al., 2019). In Asia, only 14 countries harbor substantial areas of these forests. Iran's mangroves rank 43rd globally and tenth in Asia in terms of area (Mahmoudi et al., 2022). Iran's mangroves constitute 0.2% of the mangroves in Asia and 0.08% of those in the world (Zahed et al. 2010; Hamzeh and Lahijani, 2022). The mangrove species in Iran include Avicennia marina (A. marina) (gray mangrove) and Rizophora mucronata (loop-root mangrove). Most of Iran's mangroves are located in marine national parks and protected areas, primarily along the gentler and calmer coasts of the western Strait of Hormuz. The mangrove habitats of Iran extend between the northern latitudes of 25 and 30 degrees, making them the northernmost border of mangrove forests globally and rendering them highly valuable. The mangrove forests in Bushehr Province in the vicinity of Nayband Bay, Dayyer City, and the village of Melgonzeh mark the last feasible growth areas of these forests. Of all the mangrove species described, only A. marina naturally occurs on the coasts of the Bushehr Province. These areas represent the ultimate climatic tolerance limits for mangrove shrubs and trees (Schile et al., 2017). These mangrove forests, the last distribution area of these rare habitats on the northern Persian Gulf, constitute the last global distribution range of mangroves on the northwestern shores of Asia. These habitats have lower biological productivity and biomass than mangroves in moist tropical regions globally and are more sensitive to climate change and human impacts (Ghobadi et al., 2055; Etemadi et al., 2018; Adame et al., 2021). Climate change, in addition to human impacts, can have irreversible effects on Iran's mangrove habitats, particularly in Bushehr Province, serving as an amplified stressor (Beni et al., 2021; Etemadi et al., 2021; Ghafarian et al., 2022).
While mangrove forests face multiple challenges, conservation efforts, community involvement, and sustainable management practices can help mitigate these threats and contribute to the preservation and restoration of these critical ecosystems. The regular assessment of mangrove ecosystems is crucial for conservation, sustainable management, and the well-being of both natural environments and the human communities that depend on them. In particular, helping an endangered mangrove ecosystem involves a combination of conservation efforts, community involvement, and sustainable practices. For instance, supporting conservation organizations, participating in mangrove planting programmes, educating the community, participating in clean-up events, monitoring and reporting illegal activities, and engaging with local authorities are some ways to contribute to the protection and restoration of endangered mangrove ecosystems.
Considering the aforementioned information regarding the significance of mangrove forests, especially those situated in the northern Persian Gulf, this study aimed to assess the factors contributing to the disappearance of a small mangrove forest located in Dayyer City in the northern Persian Gulf. To achieve this goal, various data sources have been compiled, including multitemporal satellite images (obtained from Google Earth), in situ field observations, and drone-based photography and mapping. Satellite imagery has been utilized to estimate variations in mangrove areas between 2011 and 2023 and to monitor the development of humanmade structures near the study area. Field observations and measurements, encompassing on-site photography and other methods, serve as evidence to uncover the reasons behind the destruction witnessed in the nominated mangrove ecosystem. Additionally, drone-based photography has facilitated the construction of an accurate, detailed map of mangroves, enabling an evaluation of their current health status. By correlating the gathered data with human-generated construction and activities, this research has highlighted the primary sources of destructive factors. Finally, several solutions have been proposed to address and mitigate the stressors impacting these affected mangrove ecosystems.