Habitat-forming intertidal algae across wave-exposures: An experimental evaluation of plant and herbivore interactions

• Main Author: Taylor, David Ian
• Format: Other/Unknown Material
• Language: English
• Published: University of Canterbury. Zoology 2002
• Subjects: New Zealand; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10092/4908; https://doi.org/10.26021/8808

Ecological factors influencing the distribution, survival and growth across wave exposures of different life stages of some intertidal habitat-forming fucoid algae in southern New Zealand and Oregon were examined. Transect and quadrat sampling in southern New Zealand showed changes in patterns of habitat-forming intertidal algae across wave-exposures. Biomass and species richness across exposures varied greatly and was concentrated in the lower tidal zone. On wave-exposed platforms lower tidal zone biomass was often dominated by the bull kelp Durvillaea antarctica, mussels Perna canaliculus or suites of red algae (Gigartina species). Biomass in the lower tidal zones at moderately exposed platforms was dominated by perennial brown algae like Cystophora torulosa, C. scalaris and was dominated by the fucoid alga Hormosira banksii and the blue mussel Mytilus galloprovincialis at sheltered sites. Invertebrate herbivore abundance and biomass were similar across exposures but the greatest species richness was found in the upper tidal zones. Predator abundance was greatest at sheltered and exposed sites that were dominated by filter-feeder habitats. Settlement experiments compared the relative ability of Hormosira banksii, Cystophora torulosa and Durvillaea antarctica, to remain attached when exposed to a low energy wave after post-settlement attachment times of 1, 6 and 12 hours. Results showed the exposed shore species D. antarctica had better attachment capabilities than C. torulosa and H banksii which are more abundant at wave protected sites. In another set of experiments zygotes were subjected to a full 12-hr tidal-cycle in the field after post-settlement attachment times of 1, 6, and 12 hours. H banksii survival was again dependent on post-settlement attachment time and showed a negative relationship with wave exposure while D. antarctica survival was not affected by wave exposure or post-settlement attachment time. In identical experiments in Oregon, survival across exposures of Fucus gardneri and Pelvetiopsis ...