Feeding habits of the exotic black bullheadAmeiurus melas(Rafinesque) in the Iberian Peninsula: first evidence of direct predation on native fish species

Abstract

The feeding ecology of the exotic invasive black bullhead Ameiurus melas was conducted in the Iberian Peninsula for the first time. Dietary analysis based on the stomach contents of individuals caught in several Iberian basins was carried out as a first step to evaluate its potential threat for the native Iberian ichthyofauna. Aquatic macroinvertebrates (mainly Chironomidae) dominated the black bullhead's diet in all size-classes and sites, irrespective of natural riverine or artificial lentic habitats. Secondary prey items were responsible for the observed between-sites (microcrustaceans in artificial lentic habitat; oligochaeta and caddisfly larvae in natural riverine habitats) and ontogenetic diet differences (from microcrustaceans to larger prey). These diet variations were also detected in trophic diversity values and feeding strategy plots. Black bullheads consumed plant material, terrestrial prey and co-occurring fish species (native or exotic) and thus they could be considered as generalist or opportunistic, foraging on the most abundant and available prey. There was no positive relationship between black bullhead size (total length) and fish prey size, probably indicating piscivory on dead or dying vulnerable fishes as well as predation on smaller-sized active fishes. The results showed that the black bullhead could negatively affect native Iberian ichthyofauna throughout direct predation and competition. Aspects of potential conservation and management implications of fishes resulting from the undesirable presence of the black bullhead in Iberian water bodies are discussed.

Ontogenetic Dietary Shifts and Food Selection of Endemic <I>Squalius Carolitertii</I> (Actinopterygii: Cypriniformes: Cyprinidae) in River Tormes, Central Spain, in Summer

“…Moreover, the preference for Baetis spp. found in this study could also be related to site-specific prey accessibility as demonstrated by other researchers (Oscoz et al 2006, Johnson et al 2007, Leunda et al 2008, Sánchez-Hernández et al 2011a.…”

Trophic plasticity of invasive juvenile largemouth bass Micropterus salmoides in Iberian streams

“…Consequently, studies detailing how invasive predators forage are of great interest to the field of invasion biology in this region, especially to those examining trophic plasticity (e.g. Almeida et al, 2009;García-Berthou, 2002;Leunda et al, 2008). Knowledge of this ecological trait would greatly aid managers in predicting the impacts of invasive species in aquatic environments (García-Berthou, 2007;Marchetti et al, 2004;Ribeiro et al, 2008;Vila-Gispert and Moreno-Amich, 2002;Wootton et al, 2000).…”

Two New Geographic Distribution Records for the Brook Stickleback, Culaea inconstans (Gastrosteiformes: Gastrosteidae), in Northwestern Nebraska

“…Several predators used in this experiment have been documented consuming trichopteran larvae in previous studies, including black bullhead (Leunda et al 2008), green sunfish (Mancini et al, 1979), and fathead minnow (Duffy 1998). Black bullheads utilize most freshwater habitats including slow moving lotic systems (Leunda et al 2008).…”

“…Black bullheads utilize most freshwater habitats including slow moving lotic systems (Leunda et al 2008). Dietary analysis conducted by Leunda et al (2008) classified them as generalists that exhibit benthophagous feeding behavior. Dominant components of their diet included microcrustaceans, caddisfly larvae, and Oligochaeta in lotic systems.…”