File(s) under permanent embargo
Fish responses to experimental fragmentation of seagrass habitat
journal contribution
posted on 2009-06-01, 00:00 authored by Peter MacreadiePeter Macreadie, J S Hindell, G P Jenkins, R M Connolly, M J KeoughUnderstanding the consequences of habitat fragmentation has come mostly from comparisons of patchy and continuous habitats. Because fragmentation is a process, it is most accurately studied by actively fragmenting large patches into multiple smaller patches. We fragmented artificial seagrass habitats and evaluated the impacts of fragmentation on fish abundance and species richness over time (1 day, 1 week, 1 month). Fish assemblages were compared among 4 treatments: control (single, continuous 9-m(2) patches); fragmented (single, continuous 9-m(2) patches fragmented to 4 discrete 1-m(2) patches); prefragmented/patchy (4 discrete 1-m(2) patches with the same arrangement as fragmented); and disturbance control (fragmented then immediately restored to continuous 9-m(2) patches). Patchy seagrass had lower species richness than actively fragmented seagrass (up to 39% fewer species after 1 week), but species richness in fragmented treatments was similar to controls. Total fish abundance did not vary among treatments and therefore was unaffected by fragmentation, patchiness, or disturbance caused during fragmentation. Patterns in species richness and abundance were consistent 1 day, 1 week, and 1 month after fragmentation. The expected decrease in fish abundance from reduced total seagrass area in fragmented and patchy seagrass appeared to be offset by greater fish density per unit area of seagrass. If fish prefer to live at edges, then the effects of seagrass habitat loss on fish abundance may have been offset by the increase (25%) in seagrass perimeter in fragmented and patchy treatments. Possibly there is some threshold of seagrass patch connectivity below which fish abundances cannot be maintained. The immediate responses of fish to experimental habitat fragmentation provided insights beyond those possible from comparisons of continuous and historically patchy habitat.
History
Journal
Conservation biologyVolume
23Issue
3Pagination
644 - 652Publisher
WileyLocation
London, Eng.Publisher DOI
ISSN
1523-1739eISSN
1523-1739Language
engPublication classification
C Journal article; C1.1 Refereed article in a scholarly journalCopyright notice
2009, WileyUsage metrics
Categories
No categories selectedKeywords
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC