Human-engineered hydrodynamic regimes as a driver of cryptic microinvertebrate assemblages on urban artificial shorelines

Eliza C. Heery*, Rachel K. E. Oh, Daisuke Taira, Dillen Ng, C. K. Chim, Rania S. Hartanto, Amanda R. Hsiung, Tiffany M. F. Chai, Lynette H. L. Loke, Hannah H. J. Yeo, Peter A. Todd

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
22 Downloads (Pure)

Abstract

[Graphical abstract presents]

Urban shorelines undergo substantial hydrodynamic changes as a result of coastal engineering and shoreline armouring that can alter sedimentation, turbidity, and other factors. These changes often coincide with major shifts in the composition and distribution of marine biota, however, rarely are hydrodynamic-mediated factors confirmed experimentally as the mechanism underpinning these shifts. This study first characterized hydrodynamic-related distribution patterns among epilithic and epiphytic microinvertebrates on urban seawalls in Singapore. We found reduced microinvertebrate abundances and distinct microinvertebrate community structure within benthic turf algae in areas where coastal defences had reduced wave energy and increased sediment deposition, among other hydrodynamic-related abiotic changes. Low-exposure areas also had reduced densities of macroinvertebrate grazers and less dense turf algae (lower mass per cm2) than adjacent high-exposure areas. Using harpacticoid copepods as a model taxon, we performed a reciprocal transplant experiment to discern between the effects of exposure-related conditions and grazing. Results from the experiment indicate that conditions associated with restricted wave energy from shoreline engineering limit harpacticoid population densities, as transplantation to low-exposure areas led to rapid reductions in abundance. At the same time, we found no effect from grazer exclusion cages, suggesting harpacticoids are minimally impacted by exposure-related gradients in gastropod macrograzer densities over short time scales. Given the key role of intertidal microinvertebrates, particularly harpacticoids, in nearshore food webs, we postulate that human-engineered hydrodynamic regimes are an important factor shaping marine ecosystem functioning in urban areas.

Original languageEnglish
Article number138348
Pages (from-to)1-12
Number of pages12
JournalScience of the Total Environment
Volume725
DOIs
Publication statusPublished - 10 Jul 2020
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Algal turf
  • Epilithic algal matrix
  • Marine urbanization
  • Artificial structures
  • Shoreline engineering
  • Seawall

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