Real-Time Monitoring of Environmental Parameters in Abu Dhabi’s Coastal Waters Using Buoy Data: Insights and Implications for Sustainable Management

The present study was carried out to study the hydrological parameters of Abu Dhabi coastal waters during January 2022 to December 2023 by using integrated real time buoy data which is an effective tool for early warning systems for conservation needs. The variations in temperature, salinity and pH were prominent in relation to stations and seasons. Pronounced changes were also observed in other parameters such as chlorophyll-a, DO and density of blue-green algae. Temperature and conductivity were found maximum at open sea coastal stations, Salinity and DO values were recorded maximum open sea coastal stations during winter month. Maximum value of pH, blue-green algal density and chlorophyll-a concentration was recorded during winter months. The spatial and seasonal variation of algal density was observed during August, June and February, which showed a strong positive correlation with the station S5 and S3, September, October, November and December had strong positive correlation with the station (S2, S8, S7, S1 and S9) and January and March had strong positive correlation with the station (S4 and S10). The findings of cluster, MDS and PCA analysis showed that variations in hydrological parameters significantly alter the Blue Green algal density. The findings of this study offer enhanced insight into how physico-chemical factors interact and vary over space and time, which is crucial for evaluating the effects of abiotic parameters. To help identify the seasonal variations, trends, and long-term changes in water quality, a long-term real time monitoring through buoy-satellite data needs to be carried out over a number of years.

Introduction

Abu Dhabi, the capital of the United Arab Emirates, is situated in an area known for its distinct and ever-changing marine and atmospheric conditions. As a centre for economic, industrial, and environmental activities, it is under increasing pressure to keep an eye on and control its natural resources, especially those related to its coastal and marine areas [1]. The Arabian Gulf, where Abu Dhabi is located, is undergoing fast changes due to natural and human causes, including global warming, pollution, and the development of coastal areas [2], [3] and these changes can significantly affect the well-being of marine biota, the quality of water, and the overall environment [4]. The realm of marine conservation and environmental stewardship has seen a significant evolution in recent years, largely propelled by technological advancements [5], [6]. Buoy-based systems are considered one of the best methods for monitoring environmental conditions in marine and coastal areas in real-time [7]. Buoys, outfitted with different sensors, provide a unique and flexible way to continuously measure important environmental factors. These measurements are essential for understanding how marine ecosystems interact with their surroundings, as well as for evaluating the effects of climate change and human activities on the coastal waters of the region [8]. The main goal of this study is to evaluate how buoy-based monitoring systems can offer precise, real-time information for managing the environment, studying climate, and protecting marine life. Additionally, we will explore the consequences of these findings for environmental management and point out the opportunities for expanding the use of buoy systems to establish a wide-ranging monitoring network in the area.

Materials and Methods

10 buoys (OSIL Tern Buoy, Fig. 1) were deployed in Abu Dhabi’s coastal waters (Al Bateen, Mussafah South Channel, Eastern Corniche, Reem Island, Al Saadiyat, Bu Tinah, Zubaya, Marawah, Umm Al Hatab and Barakah), these automated buoys stand sentinel, continuously and meticulously monitoring key parameters of marine water quality in real-time (Fig. 1 and Table I). Situated in areas of ecological significance such as confined spaces, beaches, critical marine habitats encompassing coral reefs, seagrasses, and mangroves, as well as newly developed regions and the proximity of the nuclear power plant area. The above deployed buoys are equipped with the capability to measure seven pivotal marine water quality parameters-including salinity, conductivity, temperature, pH, dissolved oxygen, chlorophyll, and Blue green algae-every 15 minutes, these buoys operate in synchrony to relay their findings to the centralised database of the Environmental Agency-Abu Dhabi on an hourly basis. This constant stream of data empowers to gain comprehensive insights into the dynamic state of marine water quality, enabling timely intervention and action in response to emergent changes such as harmful algal blooms (HAB) [9].

Fig. 1. OSIL Tern Buoy deployed in Eastern Corniche, Abu Dhabi coastal waters.

Table I. The Details of Sampling Stations are Given Below

Site ID	Location	Category
S1	Al Bateen	Public beach
S2	Mussafah South channel	Point Sources
S3	Eastern Corniche	Natural Habitat-Mangroves
S4	Reem Island	Newly Developed and Developing Area
S5	Al Saadiyat	Marine protected area
S6	Bu Tinah	Marine protected area
S7	Zubaya	Marine protected area
S8	Marawah	Marine protected area
S9	Um Al Hatab	Marine protected area
S10	Barakah	Nuclear plant

The data from buoys are transferred via the 3G or cellular modem and/or satellite to a secure web data centre, which provides an online interface for viewing the data. Further, the extracted raw data is cleaned and processed [10]. The result of the statistical analyses and graphical representations are based on pooled data for each month across the entire study period. Variations in physico-chemical parameters are shown in a box-plot. Factor Analysis was done to find out the correlation between physico-chemical and biological parameters to render the data dimensionless [11]. Spatial-temporal variation of environmental parameters collected in various stations was shown as a violin plot and boxplot, using (ggplot2 package) ‘R’ software [12]. All the above-mentioned univariate, multivariate and graphical analyses were conducted using the PRIMER7 program (Fig. 2).

Fig. 2. Map showing the sampling stations.

Results

Hydrological Parameters

In the present study, the temperature values ranged between 20.03°C and 35.78°C, with the lowest value recorded at S9 in February 2022 and the highest value recorded at S9 in August 2023. The conductivity values ranged from 55.44 mS/cm to 69.63 mS/cm, with the lowest value recorded at S2 in April 2023 and the highest value recorded at S10 in March 2022. In this study, salinity values across all coastal stations varied between 37.81 PSU and 48.28 PSU. The lowest value was recorded at S2 in May 2022, and the highest value was recorded at S9 in February 2022. The pH levels ranged between 7.66 and 8.59, indicating slightly alkaline conditions. The lowest value was recorded at S10 in February 2023, and the highest value was recorded at S3 in June 2022. Dissolved oxygen levels in the investigated area ranged from 4.02 mg/L to 7.95 mg/L. The lowest value was recorded at S2 in October 2023, and the highest value was recorded at S5 in February 2023 (Fig. 3). In this study, the concentration of chlorophyll-a in the coastal waters ranged from 0.27 mg/L to 27.09 mg/L. The lowest value was recorded at S7 in October 2022, and the highest value was recorded at S2 in March 2023. The density of blue-green algae ranged between 395.18 cells/mL and 91 401.02 cells/mL. The lowest value was recorded at S3 in November 2022, and the highest value was recorded at S2 in January 2023 (Fig. 4).

Fig. 3. Hydrological parameters recorded at Abu Dhabi coastal waters.

Fig. 4. Chlorophyll-a and Blue green algal density recorded at Abu Dhabi coastal waters.

Statistical Analysis

Cluster analysis revealed two different group formation with a 70% similarity based on the hydrographical parameters recorded at the stations. The first group consisted of sites S2 with 70% percent similarity. The rest other stations comprised the group with 88% similarity percentage. In the second group, salinity differed greatly between the sites, while conductivity, pH and temperature were distributed similarly in all the stations. The second group were further clubbed as three different batches, 1 batch consisted of S9, S7 and S5 with 99% similarity, two batch had sites such as S10, S6, S8 with 96% similarity and the third batch had S4, S1 and S3 stations, which had 92% of similarities. The stations were found to group on their own (Fig. 5) and the water parameter-based Cluster analysis demonstrated that the stations exhibited different environmental characteristics.

Fig. 5. Dendrogram for physico-chemical parameters at Abu Dhabi coastal stations.

In the present study, a significant difference was observed by sites in all parameters except temperature (Table II). A significant difference was observed according to the sites for salinity (F 40.5; P = 0.001), pH (F 2.72; P = 0.001). 02), DO (F 5.09; P = 0.001) conductivity (F 7.45; P = 0.01), chlorophyll-a (F 33.2; P = 0.001) and blue green algae (F 10.9; P = 0.001) between the samples analysed in ANOVA. Similarly, a significant difference was observed season wise in some parameters except conductivity, salinity, chlorophyll-a and blue green algae (Table II). A significant difference was observed according to the sites for temperature (F 66.4; P = 0.001), pH (F 0.49; P = 0.001). 02) and DO (F 5.46; P = 0.001) between the samples analysed in ANOVA.

Table II. ANOVA Showed Significant Variation in Water Quality Parameters of Abu Dhabi Coastal Stations

	Spatial variation			Seasonal Variation
	F	P-value	Sig.	F	P-value	Sig.
Temperature	0.64	0.756	Insig	66.415	0.000	Insig
Conductivity	7.45	0.001	Sig	1.608	0.106	Sig
Salinity	40.5	0.001	Sig	0.214	0.996	Sig
pH	2.72	0.007	Sig	0.496	0.007	Sig
D. Oxygen	5.09	0.001	Sig	5.467	0.000	Sig
Chlorophyll-a	33.2	0.001	Sig	0.222	0.996	Sig
B. Green algae	10.9	0.001	Sig	0.698	0.738	Sig

Regression Analysis of Blue Green Algal Density with Hydrological Parameters

Regression analysis indicated that the Blue green algal density values had a very slight positive relationship with temperature (Temp; r² = 0.015). Chlorophyll-a concentration had a negative relationship with temperature (Temp; r² = 0.019). Blue green algal density was positively correlated with salinity and Dissolved oxygen (Salinity; r² = 0.915: p < 0.05; DO; r² = 0.458: p < 0.05), indicating that the higher concentrations of algal density in the study area may be due to the high salinity and Dissolved oxygen (Figs. 6a–6d).

Fig. 6. Environmental factors and their relationship with the algal density: (a) Temperature vs algal density, (b) Temp vs chlorophyll, (c) salinity vs algal density and (d) DO vs algal density.

Principal Component Analysis (PCA)

Principal Component Analysis (PCA) is crucial because it simplifies complex data sets, uncovers underlying patterns, enhances the interpretability of results, and boosts the efficiency of data analysis across various applications [13]. The variation of algal density in spatial and seasonal context (Fig. 7), was done by using the principal component analysis and collectively explains 69.1% of the total variance. The spatial and seasonal variation was observed during August, June and February, which showed a strong positive correlation with the station (S5 and S3), September, October, November and December had strong positive correlation with the station (S2, S8, S7, S1, and S9) and January and March had strong positive correlation with the station (S4 and S10).

Fig. 7. Principal Component analysis shown in spatial and seasonal variation of Blue green algal density at Abu Dhabi coastal stations.

Discussion on Coastal Hydrological Parameters of Abu Dhabi

Abu Dhabi has adopted a comprehensive approach to protecting and improving its coastal water quality through monitoring programmes, enhanced wastewater treatment, marine conservation, and public engagement [14]. The Environment Agency-Abu Dhabi (EAD) plays a pivotal role by implementing extensive monitoring networks that utilise buoys, sensors, and satellite imagery to measure critical water quality parameters and identify pollution sources [15]. EAD has implemented an automated network of buoys in various locations along the UAE coastline amid extensive coral formations and seagrass beds that function as online monitoring and early-warning systems for red tides and algal blooms and these buoys continuously collect data on various water quality parameters, enabling prompt responses to environmental changes. This study highlights the significant role of buoy-based monitoring systems in assessing and managing the water quality of Abu Dhabi’s coastal waters.

Water temperature is a key factor influencing marine life, coral bleaching, and the solubility of gases like oxygen. Abu Dhabi’s waters experience significant seasonal temperature variations, with summer temperatures often exceeding 35°C. Such high temperatures can stress marine organisms, particularly corals [2], [16]. In the present study the temperature values ranged between 20.03°C and 35.78°C and previous report [17] suggested that the sea temperatures regularly exceed 34°C for several months, and can exceed 35.5°C for a week or more during extreme heat waves, while 6 months later winter sea temperatures plummet below 20°C for several months, reaching as low as 15°C during winter shamals. This seasonal variation is the largest annual temperature range occurring in marine systems globally [18] and represents an extreme physiological challenge for the UAE’s marine organisms that had evolved in more thermally stable tropical environments before colonising the Gulf [19], [20].

The salinity of Abu Dhabi’s coastal waters is relatively high, averaging around 40–43 PSU, due to high evaporation rates and limited freshwater inflow. Elevated salinity levels can impact the distribution of marine species [21], [22]. In this study, salinity values in all the coastal study areas were found to vary between 37.81 PSU and 48.28 PSU and previously in the UAE coastline it is reported to reach a maximum value of 44 PSU (compared with normal oceanic salinity of 36 PSU), while coastal lagoons and embayment’s regularly exceed 50 PSU, characterising these areas as hyper-saline [23]. Salinity can represent a major stressor for marine fauna, and the hyper-salinity of southern Gulf seawater has been associated with dwarfism in fish and various invertebrate animals as a result of the metabolic costs of coping with osmotic stress [19].

No major regional variations in the pH and conductivity were observed, which is mainly associated with water temperature, dissolved oxygen, organic matter, chlorophyll-a etc. Abu Dhabi’s coastal waters typically exhibit pH levels around 7.8–8.3 [2]. However, ocean acidification, driven by rising atmospheric CO₂, poses a long-term threat to the region’s coral reefs and shellfish [24], [25]. DO values revealed high values and presence of well oxygenated waters in the investigated area 4.02 mg/L to 7.95 mg/L. Coastal waters near Abu Dhabi generally maintain sufficient DO levels, but localised hypoxic events can occur due to organic pollution [2]. Chlorophyll-a is a proxy for phytoplankton biomass, an indicator of primary productivity. Elevated chlorophyll-a levels may indicate nutrient enrichment and potential eutrophication. In this study, the concentration of chlorophyll-a and algal density in the coastal waters was recorded maximum at S2 during winter season (March) and the lower at S3 during winter season (November). In general, low chlorophyll-a and algal diversity were generally encountered at most stations where the effect of human impacts on the coastal waters is still not significant [26], [27].

In this study, the results of multivariate statistical analysis revealed that the higher concentrations of chlorophyll-a and blue green algal density recorded in the near shore coastal stations (S1, S2, and S3) were mainly due to continuous discharge from the neighbouring industrial zones. The nearshore coastal stations fall in the point discharge zone of the surrounding industrial areas and therefore it receives large amounts of treated effluents, which alters the hydrological characteristics in this region and causes rapid rise in the values of chlorophyll-a and blue green algal density, due to high nutrient loads, leading to eutrophication. However, the concentration was found optimal toward the other open sea stations (S4–S10). Pandey et al. [28] suggested that the anthropogenic disturbances in the near shore coastal stations are always considerably higher than other stations, which results in poor environmental and ecological quality status. The results of this study were consistent with the previous observations, which presented that in all tropical coastal waters hydrological parameters of nearshore stations always vary with the open sea stations and the variations were found normal, within the previous reported range [29]. Regular monitoring of seawater quality will help to develop a mitigation plan to control the discharges into the coastal environment.

Algal blooms are a pressing environmental concern in Abu Dhabi’s coastal waters, resulting from the rapid proliferation of certain algae under favourable conditions. Nutrient enrichment from agricultural runoff, untreated wastewater, and urban stormwater is a major driver of algal blooms, alongside warm water temperatures, high salinity levels, and restricted water circulation in bays and lagoons [30]. Coastal development activities like dredging and land reclamation also release nutrients that fuel algal growth, while climate change exacerbates the issue by increasing sea temperatures and altering precipitation patterns [31]. Algal blooms have severe impacts on marine life, often causing hypoxic conditions that lead to fish kills and the disruption of benthic ecosystems.

Conclusion

The water quality of Abu Dhabi’s coastal waters is influenced by natural and anthropogenic factors. While significant efforts are being made to monitor and manage these parameters, ongoing challenges such as climate change, urbanisation, and industrialisation necessitate adaptive and integrated management approaches. Protecting water quality is not only vital for marine ecosystems but also for the economic and cultural heritage of Abu Dhabi. To address this challenge, the Environment Agency-Abu Dhabi (EAD) has implemented real-time monitoring systems using automated buoys to predict and detect blooms, supported by early warning systems to minimise their impacts. Efforts to improve wastewater management, conserve critical habitats such as seagrass beds and mangroves, and raise public awareness are integral to mitigating HABs. However, with the increasing pressures of urbanisation and climate change, there is a growing need for continued research, advanced predictive modelling, and integrated coastal management to protect Abu Dhabi’s marine ecosystems and ensure their sustainability.