EXPERIMENTAL-EVIDENCE OF SEDIMENT PREFERENCE BY EARLY-LIFE HISTORY STAGES OF WINDOWPANE (SCOPHTHALMUS-AQUOSUS)

We evaluated sediment choice by young-of-the-year (YOY) windowpane, Sc ophthalmus aquosus, in the laboratory. We gave transitional (8-18 mm S L) and larger juvenile windowpane (32-89 mm SL) a choice of sediment m ixtures, all of which were within the range observed in the field (tes ted range: sand-<1% silt/clay; mud-40-45% silt/clay). Observations (n = 1619 in four 48-h trials) were of three kinds: location, burial beha viour, and pigmentation pattern (transitional or juvenile pigmentation ). We also tested the effects of food availability and light level on sediment preference. Windowpane of all sizes preferred sand over mud i n 65-84% of all observations, but there were differences in sediment p reference, burial behaviour, and pigmentation pattern between the tran sitional and juvenile stages. Transitional windowpane were observed on sand less frequently, buried less often, and exhibited larval pigment ation more often than juveniles. Further analyses showed that transiti onal fish had a higher probability of moving from the preferred sedime nt (sand) during hours of darkness, and both stages had a higher proba bility of moving onto mud n hen food was absent. Juveniles were also m ore active when food was absent, but to a lesser extent than transitio nal fish. We believe that habitat selection may play a crucial role in determining: the distribution of YOY windowpane under natural conditi ons and will aid in our interpretation of post-settlement distribution patterns of field populations in near-shore and estuarine environment s in the Middle Atlantic Eight, USA. (C) 1998 Elsevier Science B.V. Al l rights reserved.