Anthropogenic activities on Lagos coastal waters: Impact on sea foods and human health

This study was therefore designed to assess the accumulation of both toxic and non-toxic heavy metals in the seafoods from Lagos coastal waters, microorganisms of public health importance and their antibiograms characteristics using phenotypic and molecular methods. Giant Tiger shrimp (Penaeus monodon) is an economically important sea food that is relished among many consumers. Samples were collected from fisher folks at Makoko fish landing site. The samples were analyzed; heavy metals measured include zinc, copper, cadmium, chromium, iron, nickel, manganese, lead and cobalt. Results showed concentrations of heavy metals below detectable limit were: cadmium, nickel, manganese, lead and cobalt. While, concentrations of heavy metals above acceptable limit were: zinc 4.24mg/kg, copper 4.25mg/kg, chromium 4.25mg/kg and iron 11.7mg/kg. The total viable count varied from1.20 x 10⁷ - 2.17 x 10⁷ Cfu g^-1 , and the coliforms count ranged from 1.13 x 10⁷ - 1.45 x 10⁷ Cfu g^-1. The bacteria species suspected were Proteus spp, Serratia spp, Micrococcus spp, Bacillus spp, and Citrobacter spp. Molecular confirmation of the presumptive microbial isolates revealed Vibrio parahaemolyticus (36.5 %), as the predominant species, followed by Vibrio fluvialis (34.6 %), Proteus mirabilis (23.1%), and Bacillus subtilis (5.8 %). Susceptibility to the tested antibiotics result indicated that all tested isolates were susceptible to ofloxacin, gentamicin, nalidixic acid, erythromycin, azthromycin and ciproxacin. Some of the isolates showed resistance to ampiclox, cefexime and levofloxacin revealing (90.9%) susceptibility. More so, the frequency of susceptible isolates for cefuroxime, imipenem/clastatin, nitrofurantoin and cefotaxime ranged between 81.8% and 72.7%. Augmentin and ceftriaxome/sulbatan showed (63.6%) susceptibility. This study revealed adverse impact on the selected seafood, Penaeus monodon. The occurrence of unacceptable high levels of the assayed heavy metals, with the presence of Vibrio species, Proteus species and Bacillus species already showing antibiotic resistance could pose a significant health and environmental risk to the biotic component of the environment, including the communities around Lagos costal water, there is need for consistent monitoring by appropriate regulatory agencies.