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This study compares percentage cover of benthic organisms at the
species level at Pearl and Hermes Atoll (PHA), the largest atoll in the Northwestern
Hawaiian Islands, to determine (1) the degree of difference among sites,
(2) whether wave-exposure zones explain observed patterns in benthic community
structure, and (3) whether species richness diff...
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Context 1
... must be <.011). (Table 2), were the second most abundant functional group, with atoll-wide percentage cover averaging 15.8% (SE = 1.89%). Of the 36 species found, 13 were new records for PHA (see Abbott 1989, Vroom andBraun 2010), and one (Lau- rencia crustiformans McDermid) was a new rec ord for the Northwestern Hawaiian Is- lands (Table 2). ...
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... 2), were the second most abundant functional group, with atoll-wide percentage cover averaging 15.8% (SE = 1.89%). Of the 36 species found, 13 were new records for PHA (see Abbott 1989, Vroom andBraun 2010), and one (Lau- rencia crustiformans McDermid) was a new rec ord for the Northwestern Hawaiian Is- lands (Table 2). Microdictyon setchellianum Howe was the largest contributor to overall macroalgal cover and occupied an average of 10.9% (SE = 1.83%) of the substrata when data from all sites were pooled. ...
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... sites in the intermediate-high wave-exposure zone along the E and S sides of PHA supported greater benthic community variability than either the high or low wave- exposure zones but still exhibited a relatively high degree of similarity in benthic commu- nity composition (Plate II). Although not as high as those for sites in the high wave- exposure zone, 1-D SWAN wave forces estimates for the intermediate-high wave- exposure zone were considerable (Table 2) and likely result in periodic disturbance con- ditions for many organisms ( Storlazzi et al. 2005). Disturbance may explain the relatively high abundance of the colonizing coral spe- cies Pocillopora meandrina and the robust coral species P. lobata (Table 3) ( Grigg andMaragos 1974, Storlazzi et al. 2005). ...
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... ever, the intermediate-low wave- exposure zone at PHA is a large area com- posed of both patch reefs and backreefs adja- cent to NW-, W-, S-, and E-facing forereefs (Plate II). The high residual flows and bed sheer stress (Table 2) in backreef areas during large wave events may differ substantially de- pending on the wave height and period im- pacting adjacent forereefs and also depending on the geomorphology of the adjacent reef crest ( Rooney et al. 2008). For instance, those sites near emergent reef crests are likely more protected from wave exposure than those near a submerged reef crest (Fulton and Bellwood 2005). ...
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... In addition, community composition and diversity may relate to the eutrophication status of the area . On a smaller, island-scale, variations in wave exposure (Page-Albins et al., 2012;Wallin et al., 2011), depth (Eriksson and Bergström, 2005), or substrate composition, create an assortment of habitat patches that form distinct ecosystems. Lastly, at a within-habitat scale, smaller spatial features like crevices or canopies provided by either vascular plants or algae (Archambault and Bourget, 1996;Wikström and Kautsky, 2007) add yet another layer of complexity in the chain of factors and scale influencing the biodiversity of a given coastal ecosystem. ...
... When multiple variables were correlated within a given category, we chose those with the lowest summed Pearson's r coefficient, eliminating 33 variables (Table S2). Then, following Borcard et al. (2011), to select variables that best explained the macroalgae community compositions, we conducted CCA and stepwise variable selection using the R package vegan (Oksanen et al., 2020) for all sites combined and independently for each of the six realms. We addressed multicollinearity in this second step by eliminating any variables with a variable inflation factor (VIF) > 10 (Table 1; Borcard et al., 2011). ...
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... and other erect, calcifying species. In addition, studies using macroalgae to indicate local human disturbance may be misleading because they overlook that several environmental factors influence the percent cover of macroalgae, for example exposure to wind and waves(Page-Albins et al., 2012), seasonality ...
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... These data served as input parameters (wave height, period and direction) to the Delft3D WAVE module (SWAN, or Simulating Waves Nearshore) for predicting wave behavior [78, 79]. For calibration and validation of this wave model for the Northwestern Hawaiian Islands see [80, 81]. We conducted a sensitivity analysis for our wave run-up model by varying the input parameter values and evaluating the effect on wave run-up to variations in these parameters. ...
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