Trophic interactions between native and alien palaemonid prawns and an alien gammarid in a brackish water ecosystem

Abstract

Abstract. Macroalgae are an important habitat for small mobile invertebrates such as gammarid amphipods and palaemonid prawns. Gammarid amphipods are important grazers of micro-and macroalgae whereas palaemonid prawns are feeding on macroalgae and small aquatic invertebrates including gammarids. Recently the invasive palaemonid prawn Palaemon elegans established in the Baltic Sea. As P. elegans occurs within the same habitats as the native Palaemon adspersus, it is expected that this invasion modifies the existing trophic interactions. To address this question, we experimentally investigated the feeding of the native P. adspersus and the invasive P. elegans on the benthic macroalga Cladophora glomerata and on the invasive gammarid amphipod Gammarus tigrinus. In the course of the experiment neither G. tigrinus nor Palaemon spp. had effects on filamentous macroalgae. The presence of prawns drastically increased the mortality of amphipods with no difference in the feeding efficiency between the two prawn species. To conclude, the alien prawn does not add an extra function to the trophic system of the coastal ecosystem of the Baltic Sea. Nevertheless, due to its progressively increasing densities and wide habitat range, P. elegans is expected to exert stronger predation pressure on gammarid amphipods as compared to P. adspersus alone.

A trophic cascade facilitates native habitat providers within assemblages of multiple invasive marine species

“…This was evident because when P. elegans was at high densities, there were lower densities of G. tigrinus grazers. P. elegans is known as a predator of amphipods (Kuprijanov et al 2015), and here, we demonstrate this effect can be strong-G. tigrinus population sizes were stable or declining in the presence of P. elegans but its absence allowed population sizes to more than double. All treatments involved F. radicans losing biomass, but the loss was maximized at these high grazer densities.…”

“…Another invasive decapod predator is the shrimp Palaemon elegans, which was found in regions of the Baltic Sea such as the Gulf of Gdansk soon after the year 2000 (Janas et al 2004) and was widely distributed in NE regions by 2011 (Kotta and Kuprijanov 2012). It has an ecological role similar to a native shrimp Palaemon adspersus (Kuprijanov et al 2015) but is able to occupy a wider range of habitats (Kuprijanov et al 2017). The invasive crab and shrimp are omnivorous meaning possible direct consumption impacts on multiple trophic levels.…”

Increases in temperature and freshwater inputs will shift grazing patterns of a coastal mesograzer on foundation species

“…The patchy macrophyte stands found in the DZLS, and in other eutrophic water bodies, may affect the occurrence of G. tigrinus , and therefore the grazing rates, especially in intermediate and deeper waters. Palaemonid prawns put a higher grazing pressure on G. tigrinus in unvegetated mesocosms than in vegetated ones (Kuprijanov et al, 2015). It is likely that G. tigrinus stays close to the reed belt, as described for this lagoon and other coastal waters (Zettler, 1995, 2001).…”

Desalination and temperature increase will shift seasonal grazing patterns of invasiveGammarus tigrinuson charophytes

“…The patchy macrophyte stands found in the DZLS, and in other eutrophic water bodies, may affect the occurrence of G. tigrinus , and therefore the grazing rates, especially in intermediate and deeper waters. Palaemonid prawns put a higher grazing pressure on G. tigrinus in unvegetated mesocosms, then in vegetated ones (Kuprijanov et al 2015). It is likely that G. tigrinus stays close to the reed belt, as described for this lagoon and other coastal waters (Zettler 1995, 2001).…”