Influence of different types of sessile epibionts on the community structure of mobile invertebrates in an eelgrass bed

Abstract

The variation in the biomass, abundance and diversity of mobile invertebrates in eelgrass (Zostera marina) beds has been examined in relation to various abiotic and biotic factors, such as water temperature, salinity, eelgrass biomass and epiphytic microalgae presence.However, the importance of sessile epibionts, such as macroalgae and calcific spirorbid polychaetes attached to eelgrass blades, has not been the focus of previous studies. In the present study, we examined the effects of three different sessile epibionts, namely, branched red algae, filamentous green algae, and calcific spirorbid polychaetes, on the biomass and diversity of mobile invertebrates in the eelgrass beds of Akkeshi in Northeastern Japan. The relationships of the dominant mobile invertebrate biomass, the total biomass of mobile invertebrates and the species diversity to multiple abiotic and biotic variables were analyzed using a linear mixed model. Our results show that largesized epibiotic organisms can be good predictors of the variation in the total biomass, species richness and species diversity of mobile invertebrates and the biomass of major dominant species, especially for species that have a relatively high dependency on eelgrass blades. These results suggest that the different functional groups of sessile epibionts have significant roles in determining the biomass and diversity of mobile invertebrates in eelgrass beds. The variation in the biomass, abundance and diversity of mobile invertebrates in eelgrass 28 (Zostera marina) beds has been examined in relation to various abiotic and biotic factors, such as 29 water temperature, salinity, eelgrass biomass and epiphytic microalgae presence. However, the 30 importance of sessile epibionts, such as macroalgae and calcific spirorbid polychaetes attached to 31 eelgrass blades, has not been the focus of previous studies. In the present study, we examined the 32 effects of three different sessile epibionts, namely, branched red algae, filamentous green algae, 33 and calcific spirorbid polychaetes, on the biomass and diversity of mobile invertebrates in the 34 eelgrass beds of Akkeshi in Northeastern Japan. The relationships of the dominant mobile 35 invertebrate biomass, the total biomass of mobile invertebrates and the species diversity to 36 multiple abiotic and biotic variables were analyzed using a linear mixed model. Our results show 37 that large-sized epibiotic organisms can be good predictors of the variation in the total biomass, 38 species richness and species diversity of mobile invertebrates and the biomass of major dominant 39 species, especially for species that have a relatively high dependency on eelgrass blades. These 40 results suggest that the different functional groups of sessile epibionts have significant roles in 41 determining the biomass and diversity of mobile invertebrates in eelgrass beds. The abundance, biomass and species diversity of marine benthic invertebrate communities vary 50 greatly with multiple abiotic/biotic factors. The effects of tempera...

The use of diversity indices for local assessment of marine sediment quality

“…Assessments of sediment quality may serve to test whether diversity indices respond to changes in sediment quality in a community. However, marine invertebrate communities are often also affected by small-scale environmental gradients in other environmental factors 8,9 . If an appropriate community for testing cannot be identi ed, real community responses can be masked by potential variabilities in coexisting communities 1,3 .…”