Feeding of the hyperbenthic mysid Neomysis integer in the maximum turbidity zone of the Elbe, Westerschelde and Gironde estuaries

The diet of the mysid Neomysis integer in the maximum turbidity zone (MTZ) of three European estuaries (Elbe, Westerschelde and Gironde) was investiga ted in spring 1993. The quality and quantity of the diet were assessed thro ugh measurement of the stomach fullness and microscopical analysis of the s tomach content combined with image analyses. N. integer was found to be an omnivore which mainly utilizes mesozooplankton and detritus carbon pools. T he quality of the diet did not differ between the sexes or between differen t developmental stages, although smaller individuals consumed fewer items. In all three estuaries the diet was dominated by Copepoda Calanoida (5-10 E urytemora affinis ind(-1) for adults; 2-5 ind(-1) and 2-3 ind(-1) for subad ults and juveniles, respectively) and was supplemented with Rotifera and Cl adocera. Phytoplankton and benthic organisms, though present in the stomach s, were negligible. Macrophytal detritus and amorphous material, the latter unidentifiable under the light microscope, were very abundant food items. The amorphous detritus was found to originate from the suspended sediment f locs which are characteristic for the MTZ and mainly consist of clay minera ls. The energetic value of the flocs for N. integer remains unclear. (C) 19 99 Elsevier Science B.V. All rights reserved.