The average water temperature at each station ranged from 28 - 35 °C, which was sufficient for mangrove growth. Zheng and Takeuchi (2022) stated that stomatal conductance and assimilation rate in mangrove leaves are optimal at temperatures below 35 °C. Affressia et al. (2017) stated that the temperature suitable for mangrove habitat ranges from 20 - 35 °C. Mangroves are highly adapted to extreme conditions including high temperatures ((K & BL, 2001)). However, when the temperature exceeds the peak photosynthetic temperature, photosynthetic productivity decreases and when the leaf temperature exceeds 38 - 40 °C, photosynthesis. Furthermore, high temperatures increase evaporation, resulting in increased salinity; the synergistic effects of salinity and drought can affect species diversity, size, and productivity of mangrove forests ((Sahu et al., 2015); (Ball & Sobrado, 2002)) . This can affect the plant's ability to absorb water and nutrients, which in the long run can negatively affect the health of the mangrove.

The result showed that the mud thickness from 10 existing plots ranged from 4 to 78 cm ( ). Some plots exhibited significant differences; for instance, plot 9 showed the lowest mud thickness at 10 cm, while the deepest mud thickness was recorded at 78 cm. Thicker mud thickness provided support for better mangrove growth as it provided a stable, nutrient-rich substrate ((Purwanto et al., 2022)). However, there was no consistent pattern of mud thickness across all sites, suggesting that other factors also influenced mangrove growth. In addition, this difference may be due to the presence of several large rivers that flowed throughout the year. This observation aligns with the findings of Poedjirahajoe and Matatula (2019) (E & J, 2019), who noted that areas with fewer large rivers flowing throughout the season can affect the thickness and characteristics of the mud substrate. The thickness of mud in deep water or mangrove environments can indicate sedimentation processes (Boulesteix et al., 2019). This is consistent with the statement by Noor et al. (1999) (Noor et al., 1999) that mud thickness significantly impacted the ability of mangrove vegetation to capture sediment transported by water during tidal events. The thickness of the mud affects the ability of tree roots to bind and stabilize its position.

Salinity from 10 existing plots ranged between 0.03 - 0.94% (Figure 12). Septiarusli (2006) stated that mangroves can grow well in brackish water salinity between 2 - 22 ppt or salt water with salinity reaching 38 ppt. This condition indicated a reasonable salinity condition at the river mouth. Stable and suitable salinity allows mangroves to grow optimally. Mangroves effectively regulate water balance under saline conditions by adjusting their structure to exclude salt, maintain hydraulic conductance, avoid cavitation, and limit water loss ((R & C, 2015)). Research conducted in the Sundarbans of Bangladesh showed that trees growing under low salinity conditions had higher growth rates (Polidoro et al., 2010). However, significant changes in salinity, either increases or decreases, can disrupt communities in estuarine systems, affecting the biomass, abundance, and diversity of benthic macrofauna ((Breaux et al., 2019); (Diggelen & Montagna, 2016)).

Water clarity of the 10 plots from 6 stations ranged from 10 to 89 cm (Figure 13 ). There were both increases and decreases in the level of water clarity at the Progo River estuary. This indicated a difference in the amount of sedimentation that accumulated on the riverbed. The lower the water clarity level, the thicker the sedimentation will be, which can potentially reduce productivity and alter community structure (Rahman et al., 2020). Turbidity and excessive sediment loads can harm surface water bodies due to urban development, construction activities, and agricultural practices (Muhsoni, 2020). During the wet season, the water around estuaries tends to be more turbid as the river flow carries more sediment from the land. In contrast, during the dry season, water clarity may increase (Asp et al., 2016). These changes in clarity may indicate natural seasonal dynamics, while unusual changes may suggest external disturbances.

pH range from the 10 existing plots was 7.1 - 7.8, which indicated that overall the Progo River water is a productive waters. Kaswadji (2001) stated that waters with pH 6.5 - 8.5 are waters with high productivity. The pH range observed in this study also indicated that the Progo River area is very suitable for mangrove growth. Widyastuti (1999) suggested that water pH range between 6 - 8.5 is very suitable for mangrove growth. This pH range which is almost neutral to slightly alkaline water condition can affect the quality of a water habitat, especially in the mangrove ecosystem. In maintaining the function of mangrove ecosystems, it is important to maintain soil pH within a reasonable range (Mayastuti et al., 2024).  These pH values indicate relatively balanced and ideal conditions for aquatic life, so most aquatic organisms can grow well within this pH range, including fish, plankton, and microorganisms that support mangrove ecosystems. This is supported by the Ambient Water Quality Criterion (AWQC) in the United States in 2003 which considers that the pH range of 6.5 to 9 is able to protect freshwater life.

Muttaqin et al. (2024) mentioned that the ideal dissolved oxygen range for mangroves is 3 - 7 mg/L, which supports the ecosystem's health and biodiversity. The 6 stations had ideal mean DO values ranging from 3.1 - 6.3 mg/L. Factors such as tidal height, sunlight, and distance from the edge of the mangrove significantly affect DO dynamics. During high tides, DO levels are generally higher, but can decrease rapidly at low tide, especially in areas further inside the forest. Water quality with this DO value is considered moderate, which could be due to moderate levels of organic pollution. Organic waste will be consumed by bacteria, which in the process also consume oxygen, thus lowering DO. Increasing dissolved oxygen concentration also indicates the presence of bacteria and microorganisms as organic matter decomposers (K & BL, 2001).

Several types of biota were found in the research area, such as crustaceans, gastropods, and actinopterygii. Crustaceans found included fiddler crabs (Uca spp.) and ketam crab (Gecarcinucoidea). Gastropods found included Langkitang (Melanoides tuberculata), and hermit crabs (Paguroidea). Actinopterygii found included mudskippers (Oxudercinae) and mullet (Mugil cephalus). Several vegetations were also found in the research area in the form of trees, shrubs, and herbs ( Table 2).

The Tourism Suitability Index obtained in this study indicated that there were several spots at the Progo River area which were suitable for camping/outbound, relaxing, and river tracks, while there were some spots not suitable for tourism activity (Tables 4 & 5). The stations that were suitable for camping, sitting, and river track were spot 2 (River view) and spot 6 (River island), while spot 1 (Bridge view) was only suitable for camping activities. The unsuitable spots need to be improved and better managed with expectations that in the future those spots can all be suitable for tourism activities.

Results of the ADO-ODTWA assessment indicated that the environmental conditions around the Progo River estuary in Bleberan Hamlet were generally suitable for being developed as a tourist destination, particularly in terms of accessibility, accommodation, and availability of clean water. However, only one attraction that was deemed unsuitable. Additionally, there is a need for improvements in the surrounding environment, as it tends to be quite hot. Providing shade is necessary to ensure a comfortable temperature for visitors. It is hoped that with these enhancements, the area can be transformed into a prime tourist location in the future.