Burrow association of Hemicyclops (Copepoda: Poecilostomatoida) as a possible strategy for predator avoidance

Abstract

Abstract:We examined the potential advantage of the association of Hemicyclops species with decapod burrows in their avoidance from fish predators through gut-content analysis of fishes collected from the estuary of the Tama River, Japan, and an experiment applying model burrows. The small gobiid species Pseudogobius masago, collected from an area dominated by burrows of the ocypodid crab Macrophthalmus japonicus, showed a high frequency of Hemicyclops gomsoensis in their guts relative to the other co-occurring fish species. In the experiment, no significant difference was observed in the numbers of H. gomsoensis eaten by the goby between the treatments with and without the model burrows. Another goby, Acanthogobius flavimanus, from an area dominated by burrows of the mud shrimp Upogebia major, showed very low frequencies of H. gomsoensis in their guts, as compared with those in P. masago. They had also ingested H. spinulosus and H. ctenidis, in spite of the overwhelmingly high abundance of H. gomsoensis in the burrows. The number of H. gomsoensis eaten by A. flavimanus was significantly lower in the treatments with the model burrows than in the absence of burrows. Since A. flavimanus was the most dominant demersal fish in the study area, H. gomsoensis seemed to avoid predation from this potentially strong predator by inhabiting the decapod burrows. H. ctenidis and H. spinulosus seemed to avoid predation by trespassers by inhabiting the smaller burrows of polychaetes, but this strategy may be less efficient against large predators that feed on polychaetes.

Emigration patterns of motile cryptofauna and their implications for trophic functioning in coral reefs

“…While exposure to higher‐order predators did not alter the cryptofauna community, the extreme influx of harpacticoids when interstitial access was blocked suggests they experience very high rates of predation from within rubble naturally, fuelled by high population productivity and community turnover. Indeed, copepods exhibit predator avoidance in their benthic (Dethier, 1980 ; Itoh & Nishida, 2013 ) and pelagic (Alldredge & King, 1977 ) interactions. Small‐bodied cryptofauna (specifically harpacticoids) may have risked leaving the rubble interstices to colonize newly available space from the rubble surface as larger predatory cryptobenthic fishes and decapods were comparatively low in this treatment.…”

“…Indeed, copepods exhibit predator avoidance in their benthic (Dethier, 1980;Itoh & Nishida, 2013) and pelagic (Alldredge & King, 1977) interactions. Small-bodied cryptofauna (specifically harpacticoids) may have risked leaving the rubble interstices to colonize newly available space from the rubble surface as larger predatory cryptobenthic fishes and decapods were comparatively low in this treatment.…”

Laboratory quantification of burrow utilization by the symbiotic varunid crab <i>Sestrostoma toriumii</i>

“…Itoh and Nishida (2013) experimentally deduced that the copepod Hemicyclops gomsoensis avoided fish predation by inhabiting the burrows of U. major. By living in the shrimp burrow, S. toriumii would benefit through predator avoidance.…”