MEPS 413:253-266 (2010) - DOI: https://doi.org/10.3354/meps08745
Conditional responses to increasing scales of disturbance, and potential implications for threshold dynamics in soft-sediment communities
Joanna Norkko1,2,3,*, Alf Norkko1,2,4, Simon F. Thrush5,6, Sebastian Valanko1,2,3, Heli Suurkuukka7
ABSTRACT: Disturbance-recovery experiments conducted across environmental gradients can reveal the relative importance of processes, feedbacks and threshold conditions that sustain ecosystem functioning and resilience. In the present paper we argue that threshold responses to disturbance (e.g. marked non-linear shifts in abundance of important species) are scale-, context- and species-dependent. In order to test the context-dependency in recovery dynamics of soft-sediment benthic communities, we conducted a large-scale sublittoral experiment investigating patterns in recovery of 2 functionally different groups of deposit feeders (surface vs. subsurface deposit feeders; Hydrobiidae vs. Oligochaeta) with increasing spatial scales of hypoxic disturbance in the Baltic Sea. Plots (1, 4 and 16 m2) were defaunated at 4 sandy sites (5 m depth) that varied in exposure to wind-waves, and subsequent recovery of macrofaunal abundances was monitored over 15 mo, focusing on post-larval recolonisation. Recovery patterns were site-specific, depended on the scale of disturbance, and indicated a shift in the relative importance of smaller-scale biological factors to broader-scale physical factors, i.e. waves, currents and sediment transport, when moving from sheltered to more exposed sites. We found group-specific responses, related to mode of living (epifaunal/infaunal) and dispersal potential. In addition, Hydrobiidae exhibited opportunistic population increases in response to disturbance, likely due to increased food availability. The results highlight the importance of interactions between environmental factors, and understanding natural-history characteristics and relative mobility of different taxa, when assessing both the resilience and the recovery of benthic communities.
KEY WORDS: Disturbance · Conditional recovery patterns · Scale · Soft-sediment communities · Opportunistic responses · Food availability
Full text in pdf format  | Cite this article as: Norkko J, Norkko A, Thrush SF, Valanko S, Suurkuukka H
(2010) Conditional responses to increasing scales of disturbance, and potential implications for threshold dynamics in soft-sediment communities. Mar Ecol Prog Ser 413:253-266. https://doi.org/10.3354/meps08745
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