Impacts of an invasive seaweed Sargassum hystrix var. fluitans (Børgesen 1914) on the fisheries and other economic implications for the Nigerian coastal waters

Nigerian coastline and estuarine fishing communities recently witnessed the invasion of seaweed identified as Sargassum hystrix var.fluitans (Børgesen 1914) during a 16 month survey conducted between May 2011 and August 2012.It was observed that the sea weed occurred mainly during the rainy season (May -August).The spread and distribution of Sargassum hystrix var.fluitans along the coastal and estuarine fishing communities negatively impacted fishing activities as it limited access to fishing ground, clogged fishing gears mainly mono and multifilament gillnets which resulted in loss of man hours used in clearing the seaweed and preparing the gears for next fishing trips.Floating mass of the seaweed also served as aggregating device and provided food and shelters for fish, shell fishes and juvenile sea turtles.Proximate analysis of nutrient constituent of Sargassum hystrix showed 14.33% moisture, 6.55% protein, 1.90% lipid, 18.5% ash, 58.72% carbohydrate and 17.00% fiber.Using LaMotte spectrophotometer, mineral constituent consisted of 0.48ppm nitrate nitrogen, 170.00ppm potassium and 16.70ppm phosphate which suggested that Sargassum hystrix var.fluitans can provide minerals for the development of other agricultural products of economic importance.