Feeding rates, assimilation efficiencies and growth of two amphipod species on biodeposited material from zebra mussels

Abstract

SUMMARY1. Accumulation of organic material by the zebra mussel Dreissena polymorpha is assumed to be the source of a biodeposition-based food web. However, only little is known about the importance of the biodeposited material as a food source and its contribution to increased abundances of macroinvertebrates in the presence of D. polymorpha. 2. Feeding, assimilation and growth of the amphipods Gammarus roeselii and Dikerogammarus villosus on food sources directly and indirectly associated with D. polymorpha (biodeposited material and chironomids) and on conditioned alder leaves were measured. The stoichiometry of carbon, nitrogen and phosphorus of the diets was measured as an important determining factor of food quality. 3. Chironomids had the highest nitrogen and phosphorus contents, alder leaves were depleted in nitrogen and phosphorus, and the stoichiometry of biodeposited material was intermediate. 4. Both amphipod species had highest feeding rates and assimilation efficiencies on chironomids. Gammarus roeselii fed more on biodeposited material than on alder leaves, but assimilation efficiencies were similar; D. villosus also had similar feeding rates and assimilation efficiencies on the two diets. 5. Both amphipod species had highest growth rates on chironomids and lowest growth rates on alder leaves. Both grew at intermediate rates on biodeposited material of D. polymorpha. The growth rates of the amphipod species were related to food stoichiometry. Overall, the invasive D. villosus grew faster than the indigenous G. roeselii. 6. Food resources directly and indirectly associated with D. polymorpha are potential diets for amphipods, providing further evidence for a D. polymorpha biodeposition-based food web.

Density and temperature dependent feeding rates in an established and an alien freshwater gammarid fed on chironomid larvae

“…Differences in feeding rate between sexes should be considered more strongly in future experiments. Another difference between our study and that of Gergs & Rothhaupt (2008) is that we used living chironomid larvae while the latter authors used dead (commercially available frozen) larvae. Possibly usage of dead larvae compared to usage of living larvae may have an effect on consumption rate of both gammarids.…”

Predator diet, origin or both? Factors determining responses of omnivorous amphipods to predation cues

“…Notwithstanding these discrepancies, it can perceive the presence of a fish not only as a danger, but also as information about potential food resources (Paterson et al, 2013), especially if the fish consumed chironomids-an important part of the diet of invasive amphipods (Bacela-Spychalska & van der Velde, 2013). Amphipods were found to assimilate and grow better on chironomids than on plant food (Gergs & Rothhaupt, 2008), thus chironomids seems likely to be their preferred food type. In such a situation, amphipods attracted to fish may benefit from feeding directly on fish faeces or from finding an area rich in their prey.…”

The impact of zebra mussel (Dreissena polymorpha) periostracum and biofilm cues on habitat selection by a Ponto-Caspian amphipod Dikerogammarus haemobaphes

“…The positive effect of mussels upon gammarids was observed in several studies. Chaetogammarus ischnus and Gammarus fasciatus Say, 1818 survived better in mussel colonies when exposed to fish predation (Gonzalez & Burkart 2004) and D. villosus grew faster on mussel pseudofaeces than on plant material (Gergs & Rothhaupt 2008a).…”

“…Furthermore, another Ponto-Caspian species, D. villosus, was observed in high numbers among zebra mussel shells in the field (Devin et al, 2003;Boets et al, 2010) and showed active preferences for shells and living specimens of another invasive bivalve, Corbicula fluminea (O. F. Müller, 1774), in the laboratory (Werner & Rothhaupt, 2008). Gammarids can benefit from the presence of zebra mussels by using their shells as shelters as well as utilizing food resources provided by bivalves, such as increased abundance of benthic prey, faeces and pseudofaeces (Gonzalez & Burkart, 2004;Gergs & Rothhaupt, 2008a). Moreover, gammarids living among mussel shells were found to affect their molluscan hosts by modifying their attachment to substratum and locomotion (Kobak et al, 2012) as well as biting their fresh byssal threads (Platvoet et al, 2009.…”