Spatial Analysis of Chlorophyll-a and Its Correlation with Temperature, Phosphate, and Nitrate in Marine Waters of Abu Dhabi, UAE

Chlorophyll-a is a primary indicator of phytoplankton biomass and is an essential parameter for evaluating Marine Water Quality (MWQ). This study explored the relation between sea surface temperature (SST), Chlorophyll-a (Chl-a), Phosphate (PO₄), and Nitrate (NO₃) concentrations to support in the monitoring and evaluation of the marine environment. Monthly sampling was conducted at 22 ecologically important sites in the Abu Dhabi marine environment, encompassing eight categories, including confined areas, near desalination plants, natural habitats, port and marinas, near nuclear power plant, near public beaches, newly developed area and reference (offshore water). Results revealed Chl-a concentrations ranging from 0.2 to 62.8 µg/L (mean 2.05 µg/L), SST from 18.99 to 34.93 °C (mean 28.64 °C), PO₄ from 5.46 to 2967 µg/L (mean 182.67 µg/L), and NO₃ from 14.17 to 15 599.3 µg/L (mean 369.13 µg/L). Site 2 showed the highest mean Chl-a (24.26 µg/L), PO₄ (1329.36 µg/L), and NO₃ (4316.17 µg/L), while Site 13 had the highest mean SST (29.37 °C). Confined areas recorded the highest mean concentrations of Chl-a (7.47 µg/L), PO₄ (462.28 µg/L), and NO₃ (1332.02 µg/L), while reference areas showed the highest SST (29.06 °C). Statistical analysis correlation indicated that Chl-a positively correlates with PO₄ (0.603) and NO₃ (0.433) but negatively correlates with SST (-0.076). SST showed negative correlations with PO₄ (-0.188) and NO₃ (-0.167), while PO₄ and NO₃ had a strong positive correlation (0.714). These results provide valuable information into the physical and chemical parameters and their correlations in Abu Dhabi waters

Introduction

Chlorophyll, the main pigment in photosynthesis, exists in several forms (a–f), but chlorophyll a is the primary type found in all photosynthetic algae and higher plants [1] Chl-a concentration can be considered as a direct indicator to assess the biophysical characteristics of a water body [2]. The concentration of Chl-a has also been used as a key parameter to represent water quality conditions [2]–[4]. An increase in Chl-a concentration indicates eutrophication in aquatic systems, Chl-a is considered one of the main components that contribute to turbidity in aquatic ecosystems. [5], [6]. The concentration of Chl-a varies spatially from place to place in coastal regions [2]. Some researchers have investigated the relationship between Chl-a concentration and sea surface temperature (SST) for a particular sea area [7]. Phosphate (PO₄) and Nitrate (NO₃) are needed to support plants in their growth and development, the relationship between nutrient content and Chl-a is significant to determine the productivity of water [8]. The pattern of distribution of Chl-a has a relationship with the distribution of nutrients and there is a positive relationship between PO₄ and Chl-a [9]. It is necessary to research the correlation of Chl-a content with P and N nutrients, as information on water productivity [8]. The Chl-a concentration in the phytoplankton cells changes with nutrients and environmental factors so know about the effective factors on Chl-a concentration is very important for ecosystem management [10]. Nutrient input to the sea may occur anthropogenically or naturally through physical, chemical and biological processes [11]. Increase in the phytoplankton biomass can be measured as an increase in the Chl-a concentration. Therefore, Chl-a is a useful expression of phytoplankton biomass and is arguably the single most responsive indicator of nitrogen and phosphorus enrichment in the marine system [12], [13]. Furthermore Belogum and Ajani [14] stated that Chlorophyll concentrations provide a straightforward and integrative indicator of the phytoplankton community’s response to nutrient enrichment. The distribution of NO₃ and PO₄ is closely related to the distribution of phytoplankton, although the quantity is not always the same [8].

The objective of this study is to understand the spatial distribution of Chl-a, SST, NO₃ and PO₄ along the coast of Abu Dhabi. It aimed to analyse how these parameters vary across different locations and to assess their correlations with one another. The findings provide information on parameters key relationships and potential influences on coastal water quality.

Study Area

Abu Dhabi, located at the southeastern end of the Arabian Gulf, covers approximately 80% of the United Arab Emirates’ (UAE) total land area. Saudi Arabia lies to the south and west, Oman to the north and east, and Qatar to the west. It has a coastline of 740 km, out of which 650 km is in the Arabian Gulf and 90 km in the Gulf of Oman, its marine environment is under pressure from various human activities including offshore oil exploration, coastal dredging, land reclamation and urbanisation [15]. Abu Dhabi is located in the Arabian Gulf and is characterised by an arid subtropical climate with an average of <5 cm rainfall along the coast [16]. The climate of Abu Dhabi is hot; on the coast, humidity reaches over 90 percent in summer and autumn. The temperature is high, often exceeding 50°C in summer. During winter, daytime temperatures are generally in the mid-twenties Celsius; nights can be relatively cool, with temperatures as low as 12°C–15°C, dropping to 5°C in the depths of the desert or high in the mountains. In the marine environment, the surface water temperature oscillates between 17°C and 35°C [17].

Materials and Methods

As part of its marine water quality monitoring programme, the Environment Agency—Abu Dhabi (EAD) collected monthly data on SST and Chl-a throughout 2022 from 22 sites across Abu Dhabi’s coastal waters (Fig. 1), using an in-situ Hydro Lab HL 7 instrument. Simultaneously, surface seawater samples were collected for NO₃ and PO₄ analysis. After collection, samples were stored in ice-packed coolers and transported to an Abu Dhabi Quality and Conformity Council (AD QCC)-approved external laboratory, the Arab Center for Engineering Studies (ACES), for testing according to the American Public Health Association (APHA) [18] Standard Method 4500 NO₃ (E) and 4500 P (C) 23^rd edition. The 22 sampling sites represented different ecologically important areas, including public beaches (Sites 7, 9 and 107), ports and marinas (Sites 11 and 12), confined zones (Sites 1, 2, 3 and 201), natural habitats (Sites 4, 20, 21, 22 and 123), areas near the nuclear power plant (Site 125), desalination plant areas (Sites 13, 14 and 15), newly developed areas (Sites 117, 119 and 202), and a reference offshore area (Site 126).

Fig. 1. Sampling site.

Data Analysis

The collected data were analysed to assess spatial distribution patterns, furthermore statistical analyses were conducted to examine Pearson’s correlation among parameters, using the ‘SYSTAT’ [19] statistical analysis software. This analysis provided a comprehensive understanding of spatial distribution and their correlations with one another. The findings reveal valuable insights into coastal water quality dynamics across Abu Dhabi’s monitored sites.

Results

Spatial Variation

The Chl-a concentrations across various sites (Table I) show large variability, with Site-2 having the highest range (6.78 μg/L to 62.8 μg/L) and the highest mean concentration of 24.26 μg/L. This indicates a significantly higher algal presence at Site-2 compared to other sites, which might be due to localised nutrient inputs or specific environmental conditions. Most other sites have mean Chl-a values (Fig. 2) below 2 μg/L, with narrow ranges. Site-1 and Site-3 have similar means of 1.96 μg/L and 1.94 μg/L, respectively, with maximum values around 2.9 μg/L. Sites with the lowest mean Chl-a levels include Site-125 and Site-126, with means of 0.42 μg/L and 0.51 μg/L, respectively, suggesting lower productivity or nutrient levels at these locations. The data highlights significant spatial differences in Chl-a concentrations, indicating varying ecological dynamics across the monitored sites.

Table I. Min, Max and Mean Value of Different Sites

Site	Chlorophyll a (μg/L)			Temperature (°C)			Phosphate (μg/L)			Nitrate (μg/L)
	Min	Max	Mean	Min	Max	Mean	Min	Max	Mean	Min	Max	Mean
Site-1	0.62	2.91	1.96	18.99	33.67	27.68	43.84	438.16	131.97	58.01	2255	370.42
Site-2	6.78	62.8	24.26	19.33	34.47	27.59	138.6	2967	1329.36	61.11	15599.3	4316.17
Site-3	0.92	2.92	1.94	19.43	34.27	28.28	69.29	277.49	132.91	80.16	365.8	198.57
Site-201	0.6	2.91	1.75	20.32	34.4	28.57	53.96	949.5	254.88	48.27	3705	442.92
Site-7	0.69	2.12	1.3	19.95	34.31	28.47	15.33	277.49	99.7	52.7	209.47	130.14
Site-9	0.43	1.33	0.81	21.53	34.56	29.12	15.33	211.87	95.06	46.5	254.64	131.82
Site-107	0.67	1.91	1.1	20.2	34.64	28.7	30.97	292.21	110.29	58.46	495.56	180.17
Site-117	0.56	1.16	0.76	21.43	34.82	29.07	30.97	219.23	126.92	50.04	308.67	152.97
Site-119	0.36	1.89	0.95	19.15	34.52	27.97	14.72	350.47	109.64	42.96	304.9	145.63
Site-202	0.74	3.9	1.83	20.29	34.7	29.22	61.63	562.6	179.96	49.6	3334.29	605.87
Site-13	0.41	2.64	0.93	21.49	34.65	29.37	29.13	215.8	105.67	32.77	199.7	115.22
Site-14	0.39	1.21	0.72	20.55	34.69	28.73	9.5	277.49	125.45	57.13	280.33	138.13
Site-15	0.46	0.63	0.55	21.63	34.81	28.61	87.69	107.9	95.90	48.71	178	109.71
Site-11	0.58	2.8	0.98	21.71	34.68	29.1	15.33	263.08	118.82	29.67	190.4	105.143
Site-12	0.51	1	0.7	20.52	34.61	28.54	7.67	153.31	109.62	72.63	142.16	108.615
Site-4	0.72	2.17	1.04	21.68	34.7	29.09	51.21	246.51	142.05	23.25	290.07	149.16
Site-20	0.45	0.76	0.59	21.72	34.81	28.77	124.2	161.9	137.14	74.84	171.8	118.12
Site-21	0.54	1.44	0.91	20.43	34.54	28.35	69.3	134.8	107.20	87.69	183.3	125.17
Site-22	0.47	0.8	0.58	20.18	34.93	28.79	5.46	299.57	139.81	34.54	149.2	95.31
Site-123	0.2	1.12	0.69	20.28	34.72	28.67	8.28	482.01	141.97	34.99	346.8	138.18
Site-125	0.38	0.48	0.42	20.41	34.73	28.5	17.18	164.35	109.97	48.71	203.72	134.41
Site-126	0.28	0.86	0.51	22.56	34.27	29.06	46.3	266.61	114.59	14.17	244.46	108.97

Fig. 2. Distribution of Chlorophyll a- mean value.

The SST data across different sites (Table I) reveals a relatively consistent range, with minimum SST generally between 18.99°C and 22.56°C, and maximum values reaching above 34°C across all sites. Site-1 recorded the lowest minimum SST at 18.99°C, while Site-126 observed the highest minimum at 22.56°C. Maximum SST are consistent, ranging from 33.67°C at Site-1 to 34.93°C at Site-22, indicating minimal variation in peak SST. Average SST (Fig. 3) are mostly between 27.59°C (Site-2) and 29.37°C (Site-13), reflecting stable conditions across the monitored sites. Notably, sites like Site-9, Site-117, and Site-202 have higher mean SST above 29°C, while sites such as Site-1 and Site-2 have lower averages around 27.6°C to 27.7°C. This data suggests minor variations in thermal conditions, likely influenced by localised factors such as water depth, shading, or nearby discharges.

Fig. 3. Temperature variation- mean value.

The PO₄ levels across sites display (Table I) a wide range of values, with Site-2 exhibiting the highest concentration variability. PO₄ levels at Site-2 range from 138.6 μg/L to a maximum of 2967 μg/L, with an exceptionally high mean of 1329.36 μg/L, indicating potential localised nutrient input or contamination. Other sites have significantly lower means (Fig. 4); for example, Site-1 and Site-3 both have means around 132 μg/L, with maximum values of at Site-1 438.16 μg/L. Site-201 also shows high levels, with a mean of 254.88 μg/L and a maximum of 949.5 μg/L. Sites like Site-9, Site-15, and Site-11 have comparatively low means below 120 μg/L, indicating lower PO₄ presence. The data suggests that Site-2 is an outlier with particularly high PO₄ levels, while most other sites remain within a more moderate range, likely reflecting differences in nutrient input sources and environmental conditions across locations.

Fig. 4. Phosphate Variation- mean value.

The NO₃ levels across sites (Table I) reveal substantial variability, with Site-2 standing out due to its extraordinarily high maximum value of 15 599.3 μg/L and a mean of 4316.17 μg/L. Other sites exhibit considerably lower NO₃ levels. Site-202 has the second-highest NO₃ mean (Fig. 5) at 605.87 μg/L, with a maximum of 3334.29 μg/L. Sites like Site-1 and Site-201 also display high levels of 370.42 μg/L and 442.92 μg/L, respectively. In contrast, most other sites have mean NO₃ values below 200 μg/L, with Site-22 recording one of the lowest means at 95.31 μg/L. This wide range in NO₃ levels across sites suggests varying influences of nutrient sources, with Site-2 being a potential hotspot for nutrient pollution.

Fig. 5. Nitrate Variation-mean value.

Category Wise

The measurements of Chl-a, SST, PO₄, and NO₃ levels across various environment categories (Table II) such as confined areas, public beaches, newly developed areas, locations near desalination plants, ports and marinas, natural habitats, nuclear power plants, and a reference site (Offshore). Chl-a concentrations are highest in confined areas, reaching a maximum of 62.8 µg/L and a mean of 7.47 µg/L, while other sites generally exhibit lower Chl-a levels (Table II), particularly the nuclear power plant (mean of 0.42 µg/L) and reference site (mean of 0.51 µg/L). SST values across all sites are consistent, ranging between 18.99°C and 34.93°C, with means around 28°C to 29°C. PO₄ levels vary significantly, with confined areas showing a high mean of 462.28 µg/L, while newly developed area have a mean of 138.84 µg/L, and public beaches record lower values (mean of 101.68 µg/L). NO₃ concentrations also differ, with confined areas showing the highest mean of 1332.02 µg/L, followed by newly developed areas 301.49 µg/L, Public beaches 147.38 µg/L respectively. However, reference area and port and marinas shows lower mean values of 106.87 µg/L and 108.97 µg/L.

Table II. Min, Max and Mean for Different Categories

Categories	Chlorophyll (μg/L)			Temperature (°C)			Phosphate (μg/L)			Nitrate (μg/L)
	Min	Max	Mean	Min	Max	Mean	Min	Max	Mean	Min	Max	Mean
Confined area	0.6	62.8	7.47	18.99	34.47	28.03	43.84	2967	462.28	48.27	15599.3	1332.02
Near public beaches	0.43	2.12	1.10	19.95	34.64	28.76	15.33	292.21	101.68	46.50	495.56	147.38
Newly developed area	0.36	3.9	1.18	19.15	34.82	28.75	14.72	562.6	138.84	42.96	3334.29	301.48
Near desalination plants	0.39	2.64	0.74	20.55	34.81	28.9	9.5	277.49	109	32.77	280.33	121.02
Port and marinas	0.51	2.8	0.84	20.52	34.68	28.82	7.67	263.08	114.22	29.67	190.4	106.87
Natural habitats	0.2	2.17	0.76	20.18	34.93	28.73	5.46	482.01	133.63	23.25	346.8	125.19
Near nuclear power plant	0.38	0.48	0.42	20.41	34.73	28.5	17.18	164.35	109.97	48.71	203.72	134.41
Reference	0.28	0.86	0.51	22.56	34.27	29.06	46.3	266.61	114.59	14.17	244.46	108.97

Statistical Analysis

Correlation between Chlorophyll-a to Temperature, Nitrate and Phosphate

The Pearson’s correlations were analysed using SYSTAT [19] statistical analysis software, and the results are presented in Fig. 6, revealing several important relationships among the parameters. Chl-a shows a positive correlation with PO₄ (0.603) and NO₃ (0.433). There is a negative correlation between Chl-a and SST (−0.076). SST also exhibits negative correlations with both PO₄ (−0.188) and NO₃ (−0.167), Notably, there is a strong positive correlation between PO₄ and NO₃ (0.714), implying that these nutrients often increase together.

Fig. 6. Correlation of different parameters.

Discussion

The spatial variation in Chl-a, SST, PO₄, and NO₃ levels across different sites reveals notable ecological differences and potential nutrient sources impacting water quality. Site-2 consistently shows the highest nutrient levels, with mean Chl-a reaching 24.26 μg/L and PO₄ and NO₃ levels peaking at 1329.36 μg/L and 4316.17 μg/L, respectively. These elevated levels suggest localised nutrient inputs or possible contamination from nearby outfall, making Site-2 a potential hotspot for nutrient pollution. The results of this study were higher than those observed by Al-Amara., et al. [20] and Al-Alimi et al. [21] in the Red Sea coast of Yemen, that found NO₃ values ranging from (0.249 mg/L–2.31 mg/L) but it is less than the study by Mohorjy and Hussein [23], who found the range for NO₃ was (6.90 mg/L–26.61 mg/L) in the Red Sea coast near Jeddah, Saudi Arabia [21]. Highest PO₄ levels were at Site-2 range from 138.6 μg/L to a maximum of 2967 μg/L, with an exceptionally high mean of 1329.36 μg/L, The results of this study were higher than that reported by Al-Shwafi and Mohsen [23], who found PO₄ values ranging from (0.0103 mg/L–0.0112 mg/L) in Hadhramout coast- Yemen, but it was less than that reported by Mohorjy and Hussein [23] who found the range for PO₄ was (0.74–3.81 mg/L) in the Red Sea coast near Jeddah [21].

According to EAD’s estimate, treated sewage effluent discharges into the channel amounted to approximately 400 000 m³ day^_1. This is in addition to the unidentified load of industrial effluents discharged [24]. This excess of nutrients may promote higher algal growth, as reflected by the significantly higher Chl-a concentration compared to other sites. Suryoputro et al. [9] reported that the presence of terrestrial influences through the runoff stream causes high nutrient inputs to coastal waters, this high nutrient causes Chl-a to be high. The result similar to the previous study in this location stated that the first sign of a eutrophication problem noted in Abu Dhabi was in the Mussafah South Channel during 2003 with an incident of algal blooms, corresponding fish kills and with the problems of nutrient enrichment are apparent and the key parameters involved are nitrogen, phosphorous and Chl-a [24]. The presence of a continuous bloom in the study area demonstrates the deteriorated condition of the channel and the role of nutrients and other anthropogenic activities [24]. More domestic sewage water from households and hotels were released into the ocean and find their way to the site thereby increasing the concentration of nutrients stated by [25]. Rajan et al. [24] in his study stated that the nutrient enrichment in the Mussafah South Channel has been through both point and nonpoint sources, mainly through the continuous release of nutrient-rich treated sewage from the sewage treatment plants located in Mafraq, Abu Dhabi, and other outlets on the channel [24].

In contrast, most other sites away from the anthropogenic activities exhibit lower Chl-a, with means below 2 μg/L, indicating more stable conditions. For example, Site-125 and Site-126, with Chl-a means of 0.42 μg/L and 0.51 μg/L, respectively, show lower productivity, suggesting reduced nutrient availability at these locations. The study conducted near the Gulf of Aqaba, reported similar findings, that surface Chl-a concentrations observed along the central axis of the Red Sea were ranging from less than 0.05 µg/L–0.20 µg/L [26]. Lazar et al. [27] stated that the nutrient concentrations observed in coastal waters, offshore waters show significantly lower nutrient levels. And also he stated that offshore waters have lower nutrient concentrations, influenced by dilution, lesser direct runoff, and natural processes such as upwelling and vertical mixing. [27]. The records of very low nutrient concentrations in the surface waters are in line with the absence of major nutrient inputs through continental runoff reported by Calbet et al. [26] and Garcia [28]. And also, Suryoputro et al. [9] stated that, the Chl-a distribution has decreased towards the open sea and which is related to the presence of PO₄ and NO₃ nutrients.

The SST data across sites reflects relatively consistent conditions, with mean SST ranging from 27.59°C at Site-2 to 29.37°C at Site-13. This result is slightly higher than the study in Red Sea Coastal area in Yemen, the SST values of seawater ranged between 26.00°C and 27.30°C [21]. In this study, maximum sea surface temperature (SST) values exceeded 34°C across all sites. Similar findings were reported by Mohorjy et al., 2006 [22], who recorded maximum SST values of 34°C in the Jeddah coastal area. Variation of SST showed higher values in summer compared to winter in all stations; this was associated with the air temperature, which was higher in summer. The SST variation is one of the factors in the coastal and estuarine system, which may influence the physicochemical characteristics and also influence the distribution and abundance of flora and fauna [29], [30].

Chl-a, NO₃ and PO₄ concentrations across different categories reveals significant differences, likely driven by environmental and anthropogenic factors. Confined Areas show the highest Chl-a, NO₃ and PO₄ levels, averaging 7.47, 1332.02 and 462.28 μg/L suggesting restricted water flow and potential nutrient buildup, which can promote algal growth. Garcia [26] stated that, the low flushing rates and hence poor dilution associated with rapid on-site recycling of nutrients stimulated by high water SST favour the retention of nutrients in a confined area, thus keeping them available for algal growth. Confined areas are defined as regions with restricted environmental conditions, particularly limited water flow and exchange. These include lagoons, bays, and narrow channels, which are often influenced by nearby industrial activities and wastewater discharges. Due to their reduced ability to flush out pollutants, these areas tend to experience limited dispersion and greater accumulation of contaminants. As a result, confined areas exhibit high to very high susceptibility to pollution [31]. Rajan et al. [24] stated that long-term monitoring also indicates that nutrient over-enrichment is of concern across all Abu Dhabi waters, especially in the waters surrounding Abu Dhabi City, including the Mussafah South Channel. In contrast, areas near Nuclear Power Plants, Desalination Plants, Natural Habitats and Reference sites show the lowest Chl-a, NO₃ and PO₄ concentrations indicating lower productivity and possibly less nutrient inputs. A reduction in nutrient loading has likewise contributed to the decline of harmful algal blooms (HABs) in estuarine and marine coastal environments [32]. Public Beaches and Newly Developed areas have moderate, NO₃, PO₄ and Chl-a levels, reflecting a balanced environment with occasional nutrient inputs, in addition the most of this site under this category were near the extension of the confined area channels. Coastal development alters the natural landscape and can significantly impact coastal ecosystems [33]. Zhang et al. [34] stated that rapid development and the economy, along with the anthropogenic pressures may be driving the changes in water quality. These patterns highlight how confined or industrially influenced areas tend to support higher algal growth compared to more open, less nutrient-enriched locations.

The correlation analysis conducted using SYSTAT [19] software provides further insight into the relationships among Chl-a, SST, PO₄ and NO₃. The positive correlations between Chl-a and both PO₄ (0.603) and NO₃ (0.433) suggest that increases in these nutrients promote algal growth, highlighting the potential for nutrient-driven eutrophication in nutrient-rich areas. Surface nutrient concentrations exhibit strong correlations among themselves, as well as with Chl-a water column average levels, indicating that areas with higher concentrations of nutrients tend to have higher concentrations of Chl-a. Lazar et al. [27] reported that, this correlations highlights the role of nutrients in fuelling phytoplankton blooms. A study from coral reef areas around Unguja, Zanzibar, Tanzania also stated that the concentration of Chl-a had significant positive correlations with the concentrations of PO₄ and NO₃ and the concentration of PO₄ and NO₃ also significantly positively correlated [25]. Furthermore, Suryoputro et al. [9] and Stelzer abd Lamberti [35] suggest that an increase in N concentration will affect an increase in Chl-a concentration. Conversely, the negative correlation between Chl-a and SST (−0.076) suggests that SST has a minimal direct influence on Chl-a concentrations. Limbu and Kyewalyanga [25] stated similar results in their studies SST had negative insignificant correlation with Chl-a. And also, another study by Hussein et al. [36] stated that SST negatively influenced the Chl-a concentration in the Arabian Gulf and the Gulf of Oman, especially areas in the deep sea. Negative correlations between high Chl-a concentrations and SST have also been detected in other parts of the world reported by Kitsiou and Topouzelisn [37]. A strong negative correlation indicates that both factors were corresponded in unlined correlation. Additionally, the strong positive correlation between PO₄ and NO₃ (0.714) implies a common source or shared environmental factors that elevate both nutrients simultaneously, supporting the hypothesis that nutrient pollution in some sites may be driven by external sources such sewage inflows or urban runoff. These findings emphasize the importance of monitoring nutrient levels, particularly in confined and high-risk areas, to mitigate potential eutrophication and preserve water quality in ecologically sensitive sites.

Conclusion

The study reveals significant spatial variation in Chl-a, SST, PO₄, and NO₃ concentrations across different sites in Abu Dhabi’s coastal waters, pointing to localised environmental conditions and anthropogenic influences impacting nutrient distribution and productivity. Site-2 emerged as a hotspot for nutrient pollution, with notably high levels of Chl-a, PO₄, and NO₃, likely driven by confined water flow and nutrient inputs from treated sewage or industrial discharges. Confined areas exhibited the highest nutrient concentrations, enhancing algal growth, while open or less impacted sites, such as natural habitats and areas near nuclear power plants, recorded lower Chl-a levels, indicating reduced nutrient input. Correlation analysis underscores the positive relationships between Chl-a, PO₄, and NO₃, reinforcing the role of nutrients in algal growth, while SST displayed a negative correlation with Chl-a, suggesting its minimal influence on algal presence. The strong correlation between PO₄ and NO₃ further suggests sources, potentially from urban runoff or sewage discharge. These findings highlight the importance of strengthening control measures and maintaining ongoing monitoring of nutrient levels particularly in high-risk areas to reduce the risk of eutrophication and protect the ecological integrity of Abu Dhabi’s coastal and marine environments.