Distribution of Nutrient Salts and Chlorophyll-a in Surface Water along the Gulf of Aden and Arabian Sea Coast, Yemen

Abstract

The distribution of inorganic nutrient salts (ammonium, nitrite, nitrate, phosphate and silicate) and phytoplankton chlorophyll-a (Chl-a) were investigated in the Gulf of Aden and along the Arabian Sea coast, Yemen. Seventy two surface water samples were collected during cruises in August 2014 and January 2015. The sampled area extends from As Suqayyah in the west of the Gulf of Aden to Hawf in the east. The study showed that the average values of nutrient salts (μg/l) in waters collected in August 2014 and January 2015 were 0.83 and 0.60, 10.98 and 10.03, 16.41 and 14.73, 10.36 and 8.76, and 29.72 and 22.67 for ammonium, nitrite, nitrate, phosphate and silicate, respectively. The average values of Chl-a (mg/m3) in August 2014 and January 2015 were 0.26 and 0.21, respectively. The results showed that nitrate levels were very high but those of ammonium very low. This may reflect the oxidation of ammonia to nitrite and then nitrate, leading to a very favorable ratio of ammonia and nitrate values. The low levels of dissolved inorganic nitrogen (DIN)compounds, (ammonium, nitrite, and nitrate), phosphate, silicate and Chl-a indicated that the southern coast of Yemen is not in a eutrophic condition. The highest nutrient salt values were in the eastern part of the study area, and may have resulted from water originating from the Indian Ocean and upwelling. Statistical analysis to seek correlations between nutrient salts and Chl-a show very good to excellent correlation, which may be due toconstant coastal environment.

Habitat decline of the largest known Indo-Pacific humpback dolphin (Sousa chinensis) population in poorly protected areas associated with the hypoxic zone

“…Therefore, part of heavy metals source in the seawater with high dolphin sightings may be the dolphins' own excrement and other biological sources. In addition to heavy metals, N and P, as a nutrient salts, are positively correlated with chlorophyll-a, and the N and P contents in water can be used to indicate the distribution of nutrients and biological resources in water (Al-Akhaly et al, 2020). Factors such as N, P, and heavy metals in the water of dolphin habitats where dolphin sighting rates decreased differed from those of dolphins with increased sighting rates, indicating that adequate nutrition and rich biological resources are indispensable for the preferred habitats of dolphins.…”

Distribution of Nutrients and Chlorophyll-a in a coastal waters and mesotidal estuary of Ilaje, Ondo state, South Western, Nigeria

“…Nitrate is the final oxidation product of other nitrogen compounds (nitrification) in toxic seawater having a high redox potential. The nitrate form is generally considered the most stable and predominant dissolved inorganic nitrogen in oxygenated sea water (Al-Akhaly et al, 2020). Nitrate concentrations in both (Awoye and Abereke) estuaries follow similar trends, with a range of 1.85-5.16 mg/L and 3.20-6.98 mg/L respectively (Fig.…”