Nutrient and physicochemical properties as potential causes of stress in mangroves of the central Red Sea

Abstract

Mangrove ecosystems are some of the most productive and important sinks for sediment globally. Recently, there has been an increasing interest in possible causes of stress in mangroves, such as nutrient limitation, high salinity, solar radiation and temperature. We measured different factors casing stress and determined how they influenced oxidative stress and growth biomarkers in six study sites dominated by mangroves; Al Lith, South Jeddah, Dahban, Thuwal, Rabigh and Mastorah. Significant differences (P < 0.05) were recorded in water salinities and temperatures, nitrogen and phosphorus content in sediments, and antioxidant enzyme activities in different study sites. The highest salinity (40.75 ‰) and temperature (29.32°C) were recorded in the Rabigh mangrove stand, which corresponds to the lowest dissolved oxygen (5.21 mg/L). Total organic carbon, total nitrogen and total phosphorus in sediment across the study areas were in the order Rabigh>Thuwal>Dahban>Al Lith>South Jeddah>Mastorah. Total nitrogen in mangrove leaves at Rabigh was the highest and about 1.3 times higher than the total nitrogen in South Jeddah mangrove ecosystem, very different from the ratio of total nitrogen in the sediments at Rabigh and South Jeddah mangrove ecosystems. The average values of δ13C (-17.60‰) and δ15N (2.84‰) in the six mangrove ecosystems, and the highest δ13C (-13.62‰) and δ15N (4.39‰) at Rabigh in the sediments suggest that nutrient input differed among study sites. Higher nutrient levels at Rabigh mangrove ecosystem were attributed to restricted circulation, camel grazing and land runoff with agricultural waste during seasonal flooding events. However, N limitation and possibly salinity contributed to stress in Al Lith, South Jeddah, Dahban, Thuwal, Rabigh, and Mastorah mangrove ecosystems. Salinity (r = 0.9012) contribute more to stress at Rabigh.

Complete genome sequence analysis of plant growth-promoting bacterium, Isoptericola sp. AK164 isolated from the rhizosphere of Avicennia marina growing at the Red Sea coast

“…To use these microorganisms as plant growth promoters, we assessed their ability of AK164 to grow at moderately high temperatures (37 and 45 °C), and saline media (0–5 M NaCl) were assessed using Zobell marine agar (ZM) broth. Our data as well as previous data reported in the Red Sea coastal area showed that salinity reaches 35 PSU and high electrical conductivity of (39 uS/c) indicating higher dissolved sodium chloride in the soil (Alhassan and Aljahdali 2021 ).…”

Elemental Composition of Above and Belowground Mangrove Tissue and Sediment in Managed and Unmanaged Compartments of the Matang Mangrove Forest Reserve

“…The high content of nitrogen (N) in leaves sampled from compartment 31 indicates the influence of anthropogenic activities such as agricultural activities in the catchment of the compartment [ 30 ]. Other causes could include increased N cycling associated directly with anthropogenic impacts [ 31 ]. Agricultural waste is a product of anthropogenic activities and could contribute to an increase in N values.…”

“…[ 32 ]. A possible influence of anthropogenic activities in mangrove ecosystems such as agricultural waste has been reported in the Matang mangrove ecosystem in Malaysia [ 1 ], New Zealand [ 33 ], and other impacted sites located in the central Red Sea [ 31 ]. In addition, other studies have also reported a high concentration of N in mangrove leaves compared to other mangrove tissues and sediment [ 34 , 35 ].…”

Mangrove Trace Metal Biogeochemistry Response to Global Climate Change

“…The increase in salinity following rainfall reduction favored the formation of metal-chloride complexes, which are more stable in solution and thus more easily transported and also more bioavailable. Under arid conditions, stress conditions of mangroves, based on antioxidants content in leaves, showed salinity as the source of the biggest stress in Red Sea mangroves (Alhassan and Aljahdali, 2021). Under stressful conditions, the uptake of more bioavailable metals may eventually increase.…”