A study of the feeding ecology of the flounder in the Ythan estuary was carried out between October 1970 and August 1973. The diet of the fish varied along the length of the estuary. On the mudflats in the upper estuary C orophium vo lu tat or was the main food item with Nereis divers color and Hydrobia ulvae secondarily important, but on the very soft mudflats in the middle estuary small oligocbaetee (mainly Peloscolex benedeni) and polychaetes predominated in the diet. Over mussel beds 3\Terels dlveraicolor and Carcinus maenas were important and the lower and outer part elupeids were taken in large quantities by the older age groups. Intensive study on one mudflat" the Sleek of Tai'ty, showed a seasonal change in the diet; Corophi\:un being more important in the summer, and Nereis, feco. lthica,Hydrobia and P. os. io_£l. ans in the autumn and winter.. Changes in dietbetween day and night were relatively unimportant as were the differences between age classes, though the younger fish (0 & X-group) took many Crangon vulgaria, Gammarus sp. and Meomysis integer, whilst Macoma and Hydrobia wore secondarily important to the older age groups. Trapping throughout 24-hour periods showed that the stomachs of flounders were filled over the high tide period on the mudflatsf irrespective of whether high tide occurred by day or night, whereas at low water most fish had empty stomachs. However, variations in stomach fulness at high tide occurred. 0-group flounders had significantly fuller stomachs during the day than by night, but no differences were found in the >I-group. Also to show conclusively that the >I-group fill their guts to the same extent on different tides an index of gut (stomach plus intestine) fulness was determined and found not to vary significantly between day and night.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:474220 |
| Date | January 1975 |
| Creators | Summers, R. W. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU404395 |
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