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Distribution and Community Structure of Microphytoplankton in Relation To Oceanological and Hydrobiological Studies International Journal of Oceanography and Hydrobiology Volume 49, No. 2, June 2020 ISSN 1730-413X pages (193-205) eISSN 1897-3191 Distribution and community structure of microphytoplankton in relation to increasing anthropogenic impact along coastal waters of Jeddah, the central Red Sea by Abstract 1 2 Seasonal distribution and diversity of surface Aisha A. Al-Amri , Huda A. Qari , phytoplankton have been studied in relation to 1,3, Mohsen M. El-Sherbiny * anthropogenic activities at seven locations along the coastal waters of Jeddah, Saudi Arabia in 2017. The concentration of nitrite, nitrate, ammonia, phosphate and silicate varied over wide ranges: 0.04–20.27, 0.05–29.3, 0.22–78.16, 0.02–25.90 and 43–24.50 µmol l−1, respectively. Inorganic nutrients, phytoplankton biomass and density were at eutrophic levels at two lagoon locations (4 and DOI: 10.1515/ohs-2020-0018 5), while other coastal locations showed oligotrophic Category: Original research paper characteristics of the Red Sea. Phytoplankton biomass was positively correlated with all measured inorganic Received: October 1, 2019 nutrients. The total phytoplankton density varied Accepted: November 5, 2019 between 52.4 × 103 and 40800 × 103 cells m−3 (average 6249.9 × 103 ± 10 797 × 103 cells m−3). A total of 174 species of phytoplankton (95 diatoms, 75 dinoflagellates, 3 1Department of Marine Biology, Faculty of cyanophytes and 1 silicoflagellates) were recorded in this study, with the dominance of diatoms (95.1%). Higher Marine Science, King Abdulaziz University, densities observed at lagoon locations were mainly due Jeddah 21589, Saudi Arabia to the proliferation of the diatom species Skeletonema 2 costatum and Chaetoceros decipiens. In terms of diversity, Department of Biology, Botany Section, Faculty dinoflagellates were more numerous than diatoms in July, of Science, King Abdulaziz University, otherwise mostly diatoms dominated. On the other hand, Jeddah 21589, Saudi Arabia cyanophytes were more abundant in November. Based 3 on the present study, anthropogenic activities (especially Department of Marine Sciences, Faculty of sewage effluent) in Jeddah coastal waters had a significant Science, Suez Canal University, Ismailia 41522, impact on the phytoplankton densities and diversity. Egypt Key words: nutrients, phytoplankton, coastal water, Jeddah, Red Sea * Corresponding author: [email protected] The Oceanological and Hydrobiological Studies is online at www.oandhs.pl ©Faculty of Oceanography and Geography, University of Gdańsk, Poland. All rights reserved. 194 Oceanological and Hydrobiological Studies, VOL. 49, NO. 2 | JUNE 2020 Aisha Al-Amri, Huda Qari, Mohsen El-Sherbiny Introduction activities. These situations are more likely to cause harmful effects than positive ones (Pinckney et al. Phytoplankton are known as microalgae that are 2001). well adapted to life in several aquatic ecosystems such The Red Sea is generally considered an oligotrophic as rivers, ponds and seas (Reynolds 2006). They play an ecosystem. Compared to other marine ecosystems, important role in such ecosystems by forming the base it has received little attention in studies dealing with of the food web and perform a major portion of the phytoplankton community composition. In the Red primary production, thereby maintaining the nutrient Sea, the Saudi Arabian coastal waters were even recycling within the system (Dawes 1998; Mann 1999; less explored in this respect (Dowidar 1983; Khalil Reynolds 2006). They also play an important role in et al. 1984; Shaikh et al. 1986; Khalil 1988; Touliabah the sequestration of carbon by capturing CO2 though et al. 2010). There are a number of studies that are the process of photosynthesis and sinking it toward focused on the composition of the phytoplankton the deeper parts of the ocean after their death, thus community in the western coastal waters of the Red reducing its concentration in the atmosphere and, Sea and the Gulf of Aqaba, which is the northward in turn, helping to fight global warming (Falkowski extension of the Red Sea proper (e.g. Post et al. 1996; et al. 2004). Many factors, such as light, macro- and 2002; El-Sherif & Aboul Ezz 2000; Al-Najjar et al. 2007; micronutrients, determine the successful proliferation Madkour et al. 2010; Nassar & Khairy 2014; Abbass et al. of phytoplankton in the ecosystems (Banse 1992). In 2018; El-Sherbiny et al. 2019). Despite the oligotrophic aquatic ecosystems, the effects of spatio-temporal characteristics of the Red Sea, the incorporation of heterogeneity are particularly strong, as physical and various anthropogenic inputs in few coastal locations biological processes are interlinked with each other results in the formation of eutrophic patches among both in spatial and seasonal aspects (Steele 1985). Over oligotrophic environments. Therefore, the study was the past 40 years, the human activity has increased carried out primarily to determine the spatio-temporal the flux of nitrogen and phosphorus, mainly from variation of phytoplankton and most importantly estuaries, sewage treatment plants and agricultural to assess the role of anthropogenic inputs on the activities, to the coastal waters about two and three phytoplankton community along the coastal waters of times, respectively (Howarth et al. 2002). Jeddah, the central Red Sea, Saudi Arabia. Marine eutrophication is now considered as an ecological problem, which is increasing in its Materials and methods magnitude and creating potential impacts on the coastal ecosystems worldwide (McIntyre 1995; Nixon 1995; Pearl et al. 1997). The main cause of Study area this phenomenon is the introduction of a higher concentration of inorganic nutrients into the system The present study was carried out in the coastal through various anthropogenic sources. This can waters of Jeddah, which is a fast-growing metropolitan severely affect the ecosystem, by breaking the city located by the central Red Sea. This region ecological balance, as well as the seasonality of provides many opportunities to study the effect ecosystem functions. Several man-made problems, of anthropogenic impact on the coastal marine such as the release of heavy metals, pesticides, ecosystems of the Red Sea. The presence of different persistent organic pollutants into the system as well as human interferences makes this region vulnerable the most dangerous oil spills, have a negative impact to environmental changes that can eventually affect on the growth and multiplication of phytoplankton in biotic and abiotic interactions within the system. In both coastal and open ocean regions (Echeveste et al. order to study such changes, seven sites were selected 2011; Huang et al. 2011; Matthews 2013). Many of these along the Jeddah coastline (Fig. 1). They were selected processes affect the phytoplankton productivity. The in such a way that they ultimately represent various increasing environmental pollution is another aspect regions in the system, which are not similar in terms that affects the phytoplankton dynamics mainly in of anthropogenic interference. Site 1 was located in coastal marine ecosystems (Häder & Gao 2015). The the northern part of Jeddah, where the magnitude of primary producers are easily the major target of human interference is minimal and can be considered environmental pollution, which in turn affects the as a reference location for the study. Site 2, located higher trophic organisms. Sudden changes in water in the central region, is exposed to human impact quality, such as high nutrient loading or temperature, through wastewater, while site 3, also located in the are responsible for shifting the aquatic food webs central region, is mainly affected by the presence of more toward bacteria, viruses and nano/picoplankton a desalination plant. Sites 4 and 5 represent in the www.oandhs.ug.edu.pl ©Faculty of Oceanography and Geography, University of Gdańsk, Poland. All rights reserved. Oceanological and Hydrobiological Studies, VOL. 49, NO. 2 | JUNE 2020 195 Phytoplankton of Jeddah neritic waters filter paper to prevent the disintegration of chlorophyll molecules. All filter papers were then wrapped in aluminum foil and kept in a deep freezer (−80°C). To determine inorganic nutrients, about 1 l of seawater was filtered through a membrane filter paper with a pore size of 0.45 µm, and the filtered seawater was then placed in a deep freezer until further analysis. Both chlorophyll a and inorganic nutrients were determined according to the protocols specified by Parsons et al. (1984) using a UV spectrophotometer (Shimadzu UV 1700). Phytoplankton samples were collected using a plankton net with a mesh size of 20 µm (Hydrobios) equipped with a flowmeter to determine the volume of water filtered. Horizontal towing (0.5 m below surface water) was carried out for 5 min at a speed of about 1 knot. Immediately after the collection, the phytoplankton samples were preserved with Lugol’s iodine solution and a few drops of concentrated formaldehyde solution in an amber glass bottle (Kürten et al. 2015). All samples were then stored in a cool, dark place until further analysis. Triplicate phytoplankton counts were carried Figure 1 out in a Sedgewick Rafter counting chamber using an inverted microscope (Leica DMI 3000B) according to Map showing the sampling locations in neritic water the standard procedures of LeGresley & McDermott around Jeddah, Saudi Arabia (2010). Phytoplankton species were taxonomically identified with the help of identification catalogues
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