Physicochemical interaction with faecal bacteria in characterisation of beach water quality, Gulf of Guinea, Ghana

Human activities such as industrial and agricultural waste discharges directly in the coastal areas increasingly contribute to pollution in coastal waters of Western Africa. The study employed physicochemical and faecal analysis to understand water pollution along the coast of Ghana. The physicochemical parameter such as temperature, salinity, electrical conductivity, pH, dissolved oxygen concentration, dissolved oxygen saturation, total dissolved solids, and redox potential) were measured in situ while water samples were collected determination of total suspended solids, nutrients, chlorophyll-a, and faecal bacteria. The abundance of total coliforms (4061.6 ± 4159.14 CFU/100 ml water), Escherichia coli, and Enterococcus spp. varied signicantly (p < 0.05) among the beaches. The high amount of faecal bacteria suggest microbial contamination, possible ecosystem, and health risks to water resource users. This baseline study provides evidence of coastal water contamination to improve beach water quality standards to ensure safe environmental health. between Escherichia coli and Enterococcus sp. Escherichia coli positive signicantly correlated (r = 0.662, p = 0.037) with dissolved oxygen concentration, whereas Enterococcus sp. showed positive signicant correlation with dissolved oxygen saturation (r = 0.678, p = 0.031). A positive signicant negative correlation exists between Escherichia coli (r = -0.698, p = 0.026) and Enterococcus sp. (r = --0.704, p = 0.023) with total dissolved solids.


Introduction
Coastal water bodies are impacted through pollution, deteriorating urban sanitation, land use, and hydrological changes (Armah et al. 1997, Pommepuy et al. 2005, Shuval 2006, Stewart et al. 2008). The human activities in Ghana's urban coastal regions are increasingly contributing to coastal water pollution (Lawson 2014). About 50% of the world population lives in towns and cities within 100 km of the coast (Shuval 2006, Stewart et al. 2008). Many people do not have access to clean drinking water, and numerous people die of waterborne bacterial infections (e.g., cholera and typhoid) ( The Gulf of Guinea coast resources serve as a source of seafood, recreational, educational, medicinal and an important social and economic value to the well-being of coastal communities. Major Hotels, shing industries and two major habours, Tema and Takoradi are located along the coastal area of Ghana. The discharge of e uents without inadequate treatments into nearshore waters is critical environmental issue. Biological monitoring of coastal waters in Africa is inadequate compounded by lack of continuous oceanography monitoring observations. A short survey was conducted to characterize the beach water quality through physicochemical and microbacteria assessment of near shore waters of Ghana. The speci c aim was to understand the in uence of physicochemical drivers of spatial distribution of microbacteria in beach waters. The study reveals high bacterial loads along the coast of Ghana, a threat to public health and beach users and a useful baseline for further biomonitoring in the coast of Gulf of Guinea, West Africa region.

Sampling And Analytical Methods
Sampling The ten beaches covers the eastern, central and western coastal region of Ghana ( Figure 1). The Global Position System (Garmin etrex 10 Model) (Garmin Limited, Kansas, USA) (www.garmin.com) was used to record the coordinates of the beaches. Short survey of ecological integrity of randomized selected beaches along the coastal area of Ghana was carried out from 8 to 14 October 2016. The survey aims to understand the state of beach water quality. Horiba digital multiple parameter probe (Model U-52G 30M) (Horiba Company Limited, Japan) (www.Horiba.com) was used for in situ measurements of sea surface temperature, salinity, speci c electrical conductivity, total dissolved solids, pH, redox potential, dissolved oxygen concentration and saturation in near-shore beach waters. Each parameter was recorded three times and average computed. Three replicates of water samples from each beach were collected from 10 cm depth into 500 ml clean plastic bottles for total solids, phosphate and nitrate analyses. Three replicates of water samples from each beach were also collected into 500 ml plastic bottles covered with black polyethene bags for chlorophyll-a analyses. Ten water samples were collected into 500 ml sterilized plastic bottles for bacterial examination at Laboratory at Council for Scienti c and Industrial Research (CSIR)-Water Research Institute (WRI), Accra, Ghana. The water samples were stored on ice (4 O C) during transport to the laboratory. The analysis was carried out within 12 hours of collection.

Analytical methods
Water samples from each beach were prepared using standard methods for the examination of water and wastewater (APHA 2012). Phosphates and nutrients concentrations were determined using HACH spectrophotometer (Model DR/2010) (HACH Company, Loveland, Colorado, USA) (www. hach.com) (HACH 2012). Total suspended solids (TSS) were measured gravimetrically (APHA 2012). Chlorophylla extracted from 250 ml of water samples in 96% ethanol and determined spectrophotometrically at speci c wavelength method (Wintermans &De Mots 1965). The principle behind the extraction method is that Chl-a is soluble in ethanol and absorbs light at certain wavelengths (Welschmeyer 1994). The wavelength 665 nm, 649 nm for pigments and 750 nm for turbidity correction (Lorenzen 1967). Chlorophyll-a (Chl-a) concentration (μg/l) as an indicator of phytoplankton concentration in the water column (Hinga, 1995).
Bacteria examination of waters were prepared using standard methods and membrane ltration method (Millipore 1991 ).

Results
The sea surface temperature, pH, dissolved oxygen concentration and saturation, total dissolved solids, redox potential and nitrate satis ed the normal distribution and were subjected to one-way analysis of variance (ANOVA). These physicochemical variables do not signi cantly (p > 0.05) differ among the beaches. The ranged and mean are summarized in Table 2. High loads of total coliforms, Escherichia coli and Enterococcus sp. were found in beach waters along the coast of Ghana (Table 3). Maximum bacterial loads occur in Densu, Kpeshi and Ghana Togo boarder, while minimum levels occur in Anyanui beach.  Principal components analysis showed spatial grouping of beaches based on physicochemical variables (Fig. 4A). The rst and second axes contributed to 59.43% of total variation in grouping of four clusters of beaches:(i) Anyanui; (ii) Ghana Côte d'Ivoire and Domonli (iii) Aboadzi, Kpeshi, Densu, Ghana-Togo border, and (iv) Amisa, Esiama and Muni (Fig. 2).
Redundancy analysis (RDA) indicated that environmental variables accounts for 72.42% of variation in spatial distribution of bacteria. Nitrate and total dissolved solids signi cantly (p < 0.05) in uenced the spatial distribution of total coliforms, Escherichia coli and Enterococcus sp. in the coastal beaches of Ghana (Table 4).

Discussion
High bacterial loads occurs in beaches (e.g., Densu, Kpeshi and Ghana-Togo boarder) ( Table 3) within coastal zones characterized by increased human activities such as densely populated coastal communities, industrialization, tourisms, beach Resorts, transboundary, swimming and shing activities. While minimum bacteria load occur in Anyanui beach which is characterized by less populated shing communities in the eastern coast of Ghana.
Principal components analysis indicated the beaches can be classi ed into four major clusters based on in uential physicochemical parameters:(i) cluster 1; Anyanui beach located in the eastern coast is in uence by freshwater ow from Volta River leading to low saline condition and controlled by chlorophyll-a concentration (ii) cluster 2; Ghana Côte d'Ivoire and Domonli beaches are situated in western coast and mostly in uenced by high oxygenated sea waters (iii) cluster 3; Aboadzi, Kpeshi, Densu, Ghana-Togo border beaches are located in western-central-eastern coast and characterized by increased electrical conductivity, salinity, total dissolved solids and pH; and (iv) cluster 4; Amisa, Esiama and Muni beaches are situated in the central zone and characterized by high total suspended solids, phosphate and nitrates and redox potential (Fig. 2). The grouping of the beaches shows similar characteristics in their physicochemical composition of water quality.
The combination of physicochemical and bacteria data showed (Fig. 3) showed four major groups of beaches, mainly (i) Cluster 1; Kpeshi beach is major contaminated beach with high loads of total coliform and Escherichia coli. The Kpeshi beach is located at central of coast in the Greater-Accra region, Ghana. The beach is tourism center with two major hotels, La Beach Hotel and La Palm Hotel and the location is densely populated communities along the coast. The beach swimmers and discharge of waste by these hotels may have contributed to contamination of beach water with high bacterial loads; (ii) cluster 2; Ghana Côte d'Ivoire, Domonli and Aboadzi less contaminated beaches characterized by oxygenation. These beaches are located in western region where the population may be low and less frequent beach users and hotels (iii) cluster 3; Esiama, Muni, Anyanui and Ghana-Togo border beaches with moderated contaminated beaches characterized by chlorophyll-a concentration may have minimal human impact (iv) cluster 4; Amisa and Densu beaches with second major contaminated chacteracterised by Enterroccus sp. and nitrates. Densu beach is situated in area with high populated coastal vicinity and adjoining Densu beach Restort and Bojo beach coupled with connection to Densu estuary and subsequent Densu river. The Amisa Beach is connected with Amisa estuaries and connecting Amisa River. There is increasing human activities of sh farming, animal husbandry, water transportation in theses coastal systems which can cause increased in nutrients and bacteria load.
Nitrated and total dissolved solids signi cantly (p < 0.05) drive the spatial distribution of bacteria in beach water (Table 3). Enterococcus is mostly abundant in Esiama beach in uenced by nitrated enrichment of the sea water. Whereas total coliforms and Escherichia coli abundant in Densu and Kpeshi beaches in uenced by high levels of total dissolved solids of the seawater (Fig. 4). The correlation shows the linearity between salinity, conductivity and total dissolved solids. There is also signi cant linear association among the bacteria. The correlation between physiochemical and bacteria is con rmed by the principal component ordination  30) pH was recorded in Esiama beach and the highest (9.05) at Domunli beach. The EU has set protection limits of pH ranged from 6 to 9 as harmless for sheries and aquatic life (Chapman 1996). The pH values fall within the pH ranged between 6 and 9 for natural waters and pH 0f 8.  (Chapman 1996)., Phosphate concentration is as low as 0.001 mg/L in some pristine waters (Chapman 1996).,. Phosphate is the limiting nutrient for algal growth and therefore controls the primary productivity of a surface water body are converted into nitrate. Phosphates and nitrates essential nutrients necessary for primary production and naturally replenished by river run-off (Correl 1998, Sharpley et al. 2013. Phosphates and nitrates are limiting nutrients for plant growth (Paerl &Huisman 2008). However, excess nutrients leads to phytoplankton blooms process often term as eutrophication (Kennish 2001, Nixon 1995, Smith &Schindler 2009). The major proportion of phosphate are transported to the aquatic environment from cultivated land usually in particulate form through erosion and leaching transports relatively little soluble P, as P is strongly adsorbed on clay particles (Carpenter et al. 1998, Elser et al. 2007, Sharpley et al. 2013).
The trophic state of beach water is classi ed as an ultra-oligotrophic to mesotrophic state based on chlorophyll-a concentration (0.43 to 6.13 µg/Ll Chlorophyll-a concentration in nears-shore coastal beach waters of Ghana ranged Chorkor beach (Akita et al. 2014).
Chlorophyll-a concentration ranges from 0.

Microbial water quality
The abundance (Table 1) of total coliforms Escherichia coli and Enteroccocus is low in Anyanui beach and the highest at Densu and Kpeshi beaches. The small communities have contributed low contamination at Anyanui beach. Whereas, Densu and Kpeshi beaches are characterized by densely populated human settlements, farming surrounding catchments estuaries, large industries, tourisms, beach resorts, hotels, large coastal shing communities and popular sites for beach swimmers. The possible contamination sources include untreated disposal of human and animal waste and runoff from agricultural farmlands may affect the beach water quality. In the southeast Nigeria, maximum bacterial colony count (up to 60000 CFU/100 ml) and largest variability were found in mesotidal estuaries and adjoining near-shore waters (Anita &Showell 1997). In this study is limitation and variability was not evaluated due to 10-day short survey. However, the detection of Escherichia coli and Enteroccocus sp.   (Cabral 2010, Drasar 2003. The total coliform abundance in water (mean 4,061 ± 4,149.14) exceeded the mandatory levels for the water quality for swimming from most countries (

Conclusion
The coast of Gulf of Guinea, Ghana is faced with environmental problems such as coastal pollution. The survey was conducted to investigate ecological integrity of beach water quality via physical, chemical and microbiological methods. Anyanui beach is characterized by freshwater in uence from the Volta River Lake system with the less saline condition, whereas Densu beach exhibited high saline condition. The trophic state of beach waters ranged ultra-oligotrophic to mesotrophic. Muni beach is characterized by low Chl-a concentration, whereas high concentration is found at Ghana-Togo boarder beach. Amisa beach is enriched with high nitrates concentration.
Total coliforms, Escherichia coli and Enterococcus sp. were found in beach waters cross the coast of Ghana but with low concentration at Anyanui beach. Beaches at western coast were less contaminated. Beaches at eastern coast is characterized by moderate contamination. While. beaches at central coast were mostly contaminated with bacteria. The bacteria loads in beach water is fueled signi cantly (p < 0.05) by nitrates and total dissolved solids at most contaminated beaches, Densu and Kpeshi, as demonstrated by principal component analysis and redundancy analyses.
There exists signi cant (p < 0.05) relationship between bacteria (total coliforms, Escherichia coli and Enterococcus sp.) and physicochemical parameters and among each other. Escherichia coli and Enterococcus sp. are good indicators of faecal contamination of coastal beach waters. The bacteria load in beach waters is a concern for beach swimmers, ecosystems, and public health risk. The study provides a baseline for long-term biomonitoring of coastal waters. Figure 1 A map of sampled ten selected coastal beaches in Ghana.  Principal component analysis (PCA) ordination of integrated physicochemical (thick violent arrows) and bacteria data (thin blue arrows) (triangles). The long arrow indicates most in uential environmental variables at beaches, mainly total dissolved solids, nitrates, and bacteria loads.