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Macrobenthos of shipwrecks within and around the Belgian waters as a potential food resource for resident fish populations
Crawford, O. (2005). Macrobenthos of shipwrecks within and around the Belgian waters as a potential food resource for resident fish populations. MSc Thesis. Universiteit Antwerpen/Vrije Universiteit Brussel: Brussel. 69 pp.
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| Beschikbaar in | Auteur |
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Documenttype: Doctoraat/Thesis/Eindwerk
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| Trefwoorden |
Aquatic communities > Benthos
Wrecks
Dicentrarchus labrax (Linnaeus, 1758) [WoRMS]; Gadus morhua Linnaeus, 1758 [WoRMS]
ANE, België [Marine Regions]
Marien/Kust |
| Abstract |
The stomachs of 26 Dicentrarchus labrax (Bass) and 45 Gadus morhua (Cod) were collected between September 2004 and March 2005, from the catches of sport fishermen fishing above shipwrecks. Stomach content analysis was performed to ascertain whether or not these fish had, firstly, fed on the macrobenthos of shipwrecks and secondly, how important it was to their diets. Stomach content was quantified by percentage by weight, prey-specific abundance and frequency of occurrence. Univariate and multivariate techniques were then used to determine prey item importance. Fish dominated the Bass ., diet (95.36% ), with only Trachurus trachurus identified, whilst a small number of individuals specialised on Brachyura. Pagurus bemhardus was the only food item identified on shipwrecks but is not exclusive to hard substrates. It contributed minimally to the diet. Thus the macrobenthos of shipwrecks was deemed of little importance to Bass when fish are plentiful. In terms of percentage by weight, fish also dominated the diet of Cod (81.74%). However, analysis at the individual level revealed certain shipwreck macrobenthos to be of interest. Yet to be of importance the prey had to be of either sufficient size (e.g. Necora puber, Pilumnus hirtellus) or of substantial number (Pisidia longicomis and Ophiothrix fragilis). Buccinum undatum was also specialised upon but could not be confirmed as originating from shipwrecks. The most abundant fauna of shipwrecks, Tubularia indivisa (Hydrozoa) and Jassa herdmani (Amphipoda), proved to be of low importance and their consumption was likely unintentional due to their small size and vast coverage. The near absence of shipwreck macrobenthos in Bass stomachs and relative frequency in Cod stomachs can be attributed to the Cod's greater adaptation to feeding from the bottom. The greater importance of fish compared to crustaceans was likely due to their superior energy content. |
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