Predation by the mysid shrimps Mysis mixta and M. relicta on benthic eggs of Bosmina longispina maritima (Cladocera) in the northern Baltic Sea

Abstract

The abundance of Bosmina longispina maritima (Cladocera), the most common water flea in the Baltic Sea, shows considerable interannual fluctuations.The number of Bosmina resting eggs (ephippia) in the sediment also fluctuates from year to year. Biotic as well as abiotic factors have been suggested to contribute to these fluctuations, but the impact of benthic predation by pelagic mysids has not yet been considered. The objective of this study was to investigate the effect of benthic predation and bioturbation by Mysis mixta and M. relicta on the ephippia of B. longispina maritima on the SW coast of Finland. The results show that mysids can significantly affect the number of Bosmina eggs in the sediment. All size groups of both mysid species preyed upon ephippia of B. longispina maritima both in the water column and directly from the top layer of sediment, whereas they rejected the eggs of another cladoceran species, Pleopsis polyphemoides. The predation rate on B. longispina maritima ephippia was significantly lower when the eggs were buried under a sediment layer of ca. 1 cm. This suggests that factors affecting the vertical distribution of ephippia in the sediment determine the magnitude of the impact that mysids have on B. longispina maritima benthic eggs. KEY WORDS: Bosmina longispina maritima · Resting eggs · Mysis mixta · M. relicta · Benthic predation · Baltic SeaResale or republication not permitted without written consent of the publisher

Behavioral, Ecological and Genetic Differentiation in an Open Environment—A Study of a Mysid Population in the Baltic Sea

“…For example, omnivorous crayfish display trophic positions close to those of predatory fish –which is higher than would be expected from gut content analysis alone [73]. Mysids feeding on meiofauna, zooplankton resting eggs and small amphipods [74], [75] could have contributed to this apparent similarity in δ 13 C between the groups at station S1. The more carnivorous nature of pelagic mysids [13] is further supported by substantially stronger δ 15 N, δ 13 C-correlations as compared to benthic individuals that appear to have broader, more omnivorous diets.…”

Effects of bioturbation by three macrozoobenthic species and predation by necto-benthic mysids on cladoceran benthic eggs

“…-1 in only 12 h (Viitasalo & Viitasalo 2004). However, except for the statistically insignificant additional decrease in ephippia (< 3 d -1 ) in the treatment combining Monoporeia with mysids, no such effect was observed, i.e.…”

“…According to Viitasalo & Viitasalo (2004) Mysis mixta is unable to feed on ephippia buried in sediment; hence, it was suggested that bioturbation by macrofauna may essentially affect the predation by epibenthic mysids on their non-motile benthic prey. Consequently, one aim of this study was to test whether macrofauna could, by means of particle mixing, redistribute ephippia, buried under a sediment layer of 0.5 to 1 cm, within the reach of the mysids. )…”

“…Recently, M. mixta was found to eat Bosmina ephippia distributed on the sediment surface (Viitasalo & Viitasalo 2004). In contrast, mysids appeared incapable of feeding on ephippia that were mixed within the sediment, suggesting that the vertical distribution of sedimented ephippia is crucial not only for the recruitment of cladocerans but also for the rate of epibenthic predation by mysids (Viitasalo & Viitasalo 2004).…”

Feasibility of a flip-chip approach to integrate an IR filter and an IR detector in a future gas detection cell

“…Highly selective interferometric filters are formed by tens of these layers [4]. Less selective but more feasible filters can be got with a more modest number of layers (as few as three) following a Fabry-Perot scheme [5]. In silicon processing environments, silicon dioxide and polysilicon layers can play the role of low and high index materials.…”