Fish larvae in the hyperbenthal of Belgian coastal waters
Dewicke, A.; Beyst, B.; Mees, J. (1998). Fish larvae in the hyperbenthal of Belgian coastal waters. Biol. Jb. Dodonaea 65: 134-135 In: Biologisch Jaarboek (Dodonaea). Koninklijk Natuurwetenschappelijk Genootschap Dodonaea: Gent. ISSN 0366-0818, more |
| Keywords | Conferences
Developmental stages > Larvae > Fish larvae
Water bodies > Coastal waters
Belgium [Marine Regions]
Marine/Coastal |
| Abstract | The hyperbenthic fauna of the Belgian coastal area was sampled monthly at 8 stations from September 1994 through July 1995. All stations were located in the subtidal (6 to 20 m), covering the coastal sandbanks in the area and the gullies separating them. Samples were taken with a hyperbenthic sledge equipped with four nets (1 mm and 0,5 mm mesh size ), covering two lower strata of the water column: 0 to 0,5 m and 0,5 to 1 m above the bottom. Trawling (5 minutes at 1.5 knots: approx. 200 metres per trawl) was always done during daytime and against the tide. The sledge was equipped with an automatic opening-closing device, an odometer and a current meter. Por this study, attention was focused on the occurrence of fish larvae in the hyperbenthic layer. Species composition, densities (numbers per 100 m3) and seasonal distribution pattems for the common species were described. Density data were subjected to multivariate statistical analyses. Larval and postlarval stages of twenty fish species were present in the subtidal area of the Belgian coast. The dominant species were sole Solea solea, flounder Pleuronectes flesus and gobies Pomatoschistus species with mean densities exceeding 200 N/100 m3 in periods of maximum occurrence. Clupeid larvae and dab Limanda limanda occurred at lower densities, but were still important. The seasonal appearance, high abundance and disappearance of fish larvae in the hyperbenthic stratum of the water column was often striking. Total densities were highest during April and May, due to the recruitment of flatfish species. Pleuronectes flesus was nearly exclusively found in April, at mean densities of 262N/I00 m3. In May, peak densities were found for Solea solea (mean density of 205N/ 100 m3), although recruitment of this species started already in April and continued through June. Limanda limanda occurred in the same period as Solea solea, but at much lower densities. Postlarval gobies were caught almost throughout the year, although the highest abundances were recorded in July. Multivariate analyses on densities per station (yearly averages) reveal- ed a distinction between stations located onshore (shallow subtidal) and more seaward stations (deeper subtidal). Higher densities of fish larvae were recorded in shallow waters and species composition was changing offshore. Postlarval Gobiidae, Soleidae and Pleuronectidae occurred with higher numbers in onshore stations. Clupeidae showed two abundance peaks in offshore waters, while only one recruitment period could be detected onshore. Like for Clupeidae, early post-larval Gadidae and Callionymidae were more abundant offshore. The high numbers of larval and postlarval stages of fish in the subtidal area of Belgian coastal waters (especially the shallow subtidal) emphasizes its nursery function. The extensive sandbank system probably provides a sheltered environment suitable for the development of early life history stages of fish. |
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