Fig 1.
Study site locations (colored stars) at Ulithi Atoll and at neighboring Turtle Islands.
Sites were classified according to relative levels of impact from human activities and exposure to NE trade winds and the prevailing swell direction: Red—Inhabited, Lagoonal, Green—Uninhabited, Lagoonal, Blue—Uninhabited, Oceanic, Purple—Inhabited, Oceanic. The location of Ulithi Atoll in the western Pacific Ocean is shown in the inset (blue star, upper right).
Table 1.
List of study sites on Ulithi Atoll, Yap State, Federated States of Micronesia.
Columns from left to right correspond to: the site code as it appears on Fig 2, site name, human presence (inhabited/uninhabited during the study period) as it appears on Fig 2, whether the site was located within the Ulithi lagoon or exposed directly to the ocean, the island with jurisdiction for reef and fishery management, sampling (fish transects f, benthic quadrats b), straight line distance (km) between the site and the boat launch site for the island with jurisdiction, the human population of that island, and the GPS coordinates. *UAR4 and Yea3 were ca. 15 m deep, and surveyed on SCUBA.
Fig 2.
Dendrograms (Ward’s minimum variance method) of Ulithi Atoll sites based on benthic functional groups (2013 and 2014; bray-curtis dissimilarity index; left panel), and fish communities (2012, 2013 and 2014; cao dissimilarity index; right panel).
The sites, ‘Mogp13a’ and ‘Mogp13b’, are, like all of the MogMog sites, ‘lagoonal’, but experience little if any fishing pressure due to the presence of a poisonous corallimorph [28].
Fig 3.
Benthic cover (% cover) compared across sites from cluster 1 (uninhabited, oceanic), cluster 2 (inhabited, oceanic), and cluster 3 (inhabited & uninhabited, lagoonal) (a-f).
The relative abundance of hard coral morphotypes is shown for the 3 site clusters in e1-e3. Note that the opportunistic Montipora sp. is considered separately from all other stony corals for both cover and morphotype. The box-and-whisker plots show the median value (dark horizontal bar); the box length is the interquartile range, the upper whisker marks the smaller of the maximum value and quartile 3+1.5 interquartile range (IQR), and the lower whisker marks the larger of the smallest value and quartile 1–1.5 IQR. Outliers are not shown. Plots produced using the R package graphics, version 3.3.1.
Fig 4.
Fish biomass, abundance and size on Ulithi Atoll.
Fish trophic categories (Piscivores, Carnivores, Corallivores, Planktivores, and Herbivores) are compared among site groups (cluster 1: uninhabited, oceanic; cluster 2: inhabited, oceanic; cluster 3: inhabited & uninhabited, lagoonal) for biomass (a-e), numerical abundance (g-k) and average length (TL, m-q). The stacked bar plots (f & l) show the mean values from sites within each of the 3 clusters, and the dot chart (r) compares the mean TL for fishes from trophic categories found within sites from the 3 clusters. The box-and-whisker plots show the median value (dark horizontal bar); the box length is the interquartile range, the upper whisker marks the smaller of the maximum value and quartile 3+1.5 interquartile range (IQR), and the lower whisker marks the larger of the smallest value and quartile 1–1.5 IQR. Outliers are not shown. Plots produced using the R package graphics, version 3.3.1.
Table 2.
Environmental effects and fish community structure.
PERMANOVA results from the model fish ~ exposure + distance + population, stratified by year and terms added sequentially (first to last). Df = degree(s) of freedom, SS = Sums of Squares, MS = Mean Squares, F = F statistic obtained from the model, R2 = coefficient of determination, and p = probability of the obtained (model) F exceeding the predicted F statistic by chance.
Table 3.
Environmental effects and benthic cover composition.
PERMANOVA results from the model benthic ~ exposure + distance * population, stratified by year and terms added sequentially (first to last). Df = degree(s) of freedom, SS = Sums of Squares, MS = Mean Squares, F = F statistic obtained from the model, R2 = coefficient of determination, and p = probability of the obtained (model) F exceeding the predicted F statistic by chance.
Table 4.
Benthic cover composition and fish community structure.
PERMANOVA results from the model fish ~ Acro_thicket + Acro_table + Mound1 + Mound2 + Branch1 + Branch2 + Encrust + Foliose + Sheet + Solitary + Columnar + Montipora + Coral-Monti + Soft + Fleshy + Macroalg + Turf + CCA, terms added sequentially (first to last). Note that Coral-Monti refers to all stony corals not including the outbreak species of Montipora. Df = degree(s) of freedom, SS = Sums of Squares, MS = Mean Squares, F = F statistic obtained from the model, R2 = coefficient of determination, and p = probability of the obtained (model) F exceeding the predicted F statistic by chance. See S2 Table for a description of the benthic cover codes.