Independent effects of grazing and tide pool habitats on the early colonisation of an intertidal community on western Antarctic Peninsula

Abstract

Background: Prevailing environmental conditions can modulate the structuring role of biotic interactions. In intertidal habitats, less stressful environmental conditions and/or higher grazer densities may allow grazing effects to be stronger in tide pools than on emergent rocks. To test this hypothesis, we conducted a manipulative experiment on an intertidal rocky shore in Fildes Bay, King George Island, in which the effect of the dominant grazer Nacella polaris on the structure of benthic periphyton communities was compared between emergent rock and tide pool habitats. Also, we determined the spatial variation in density, weight, and maximum length of individuals of N. polaris in both habitats. Results: The density of N. polaris was significantly larger in tide pools than on emergent rocks. Contrarily, we observed no significant differences in morphological parameters of N. polaris between both habitats or between intertidal elevations. In the manipulative study, we observed a greater taxonomic richness, diversity, and abundance of periphyton on emergent rocks than in tide pools. These variables also showed, in comparison with control areas, significantly higher values in experimental areas where herbivores were excluded by means of stainless-steel fences. The effects of habitat and grazer exclusion treatments were independent of each other, as no statistically significant interaction between both factors was observed. Conclusions: Our results showed significant, but independent, effects of tide pool habitats and grazing on the early colonisation of these assemblages. Albeit the grazing effects of other herbivores such as amphipods and small gastropods cannot be ruled out, we suggest that traits of N. polaris, such as high mobility and circadian activity, allow this species to exert a firm control on the intertidal Antarctic assemblages across local environmental conditions.

Contoured Vertical Distribution and Spatio-temporal Variation of an Intertidal Macroalgal Assemblage in King George Island, Antarctica

“…The main distinction between the sites is that site A has more reddish coastscapes due to the presence of Palmaria decipiens. Looking at several previous intertidal studies of macroalgal assemblages or benthic communities associated with macroalgae conducted around Maxwell Bay [25][26][27][28]36,37 , the assemblages differed from our ndings and revealed signi cant heterogeneity between studies (Fig. 2).…”

“…Notably, the macroalgal assemblage in the lower part was similar to our ndings. Moreover, A. utricularis and Urospora penicilliformis appeared (Dec. 2013 to Feb. 2014) exclusively on the emergent rock in the intertidal zone northeast of Fildes Bay, about 10 km from the Barton Peninsula; in the tide pool, CCA was the predominant species and I. cordata and A. utricularis were mainly distributed 37 . Valdivia, et al 28 reported that Ulothrix sp.…”

“…The data were rearranged and pooled by site, and CLUSTER analysis was then performed based on our results. Data from 9 sites and 11 were reported in four studies [26][27][28]37 . The major and minor species were classi ed based on the criterion of coverage of 5% among the species, and the relative coverage was calculated by the point or site.…”

Biodiversity of periphytic cyanobacteria and algae assemblages in polar region: a case study of the vicinity of Arctowski Polish Antarctic Station (King George Island, Antarctica)

“…Other dominants were Planothidium lanceolatum, Achnanthidium pyrenaicum, Tabularia tabulata, Pinnularia microstauron, Gomphonella olivacea, Hantzschia abundans and Nitzschia commutata. Some authors also identified similar periphyton taxa (of the genera Fragilaria, Navicula, Tabellaria, Nitzschia) which colonized the artificial substrates in this Antarctic region (Segovia-Rivera and Valdivia 2016) and natural ones in subarctic lake (Maltais and Warwick 1997). P. borealis and F. capucina was also noted in the island King George Island (Vinocur and Pizarro 2000).…”

Heterogeneity of ecological patterns, processes, and funding of marine manipulative field experiments conducted in Southeastern Pacific coastal ecosystems

“…Subtropical and temperate systems from 20°S to 40°S have been the most studied, but with notable experimental studies conducted in intertidal and subtidal habitats in the Galápagos Islands (e.g., Brandt, Witman, & Chiriboga, ; Irving & Witman, ; Vinueza, Branch, Branch, & Bustamante, ; Vinueza et al., ). Although our study encompasses an ample geographic gradient, we did not consider emergent experimental studies conducted in the Antarctic Peninsula (e.g., Segovia‐Rivera & Valdivia, ) which examined the main processes structuring coastal communities in extreme environmental conditions.…”