Fig 1.
Coral and algae of the Southern Line Islands.
Common genera of corals and algae across the Southern Line Islands in the Republic of Kiribati, central Pacific. (a) The crustose coralline alga, Porolithon sp. and (b) the corals Pocillopora meandrina and (c) Montipora aequituberculata were collected from all five islands. (d) The fleshy green alga Avrainvillea amadelpha was found only at Vostok and Malden, and (e) the calcareous green alga, Halimeda sp., was found at Flint, Millennium and Starbuck.
Fig 2.
Surface-ocean chl a during cruise.
Average surface-ocean chl a concentrations increased from south to north across the Southern Line Islands over four months encompassing the research expedition. Surface chl a (mg mg-3) was estimated from the eight-day 0.0417° (4 km) spatial resolution product derived from the Moderate Resolution Imaging Spectroradiometer, and concentrations ranged from 0.01 (blue) to 0.17 mg mg-3 (red) across the archipelago.
Table 1.
Environmental parameters across the Southern Line Islands, with islands listed from south to north.
Fig 3.
Coral and algal metabolism and photosynthetic efficiency.
Box plots of gross photosynthesis and maximum quantum yield of (a-b) Porolithon sp., (c-d) Halimeda sp., (e-f) Avrainvillea amadelpha, (g-h) Pocillopora meandrina, and (i-j) Montipora aequituberculata. Islands are ordered from south to north across the x-axis (from left to right), and missing bars indicate where a given species was not present at an island. Due to logistical difficulties, there were no maximum quantum yield measurements at Flint or photosynthesis measurements from Porolithon at Starbuck. Significant differences between islands were determined by Tukey’s HSD, different letters represent significant differences at p < 0.05. Gross photosynthetic rates for Porolithon and corals were normalized to surface area, and are expressed as μmol O2 cm-2 hr-1. *Rates for the algae, Halimeda and Avrainvillea, were normalized to fresh weight, thus for those taxa the units are μmol O2 mg-2 hr-1.
Table 2.
Photosynthesis and respiration rates.
Fig 4.
Photosynthetic pigments of corals and algae.
Box plots of chl a and carotenoid concentrations in (a-b) Porolithon sp., (c-d) Halimeda sp., (e-f) Avrainvillea amadelpha, (g-h) Pocillopora meandrina, and (i-j) Montipora aequituberculata. Islands are ordered from south to north across the x-axis (from left to right), and missing bars indicate where a given species was not present at an island. Significant differences between islands were determined by Tukey’s HSD, different letters represent significant differences at p < 0.05. Porolithon and coral pigment concentrations were normalized to surface area, and rates are expressed as μg cm-2*. *Halimeda and Avrainvillea pigment concentrations were normalized to fresh weight, thus units for those taxa are μg mg-2.
Fig 5.
Phycobilin pigment concentrations.
Mean (± SE) phycobilin pigment concentrations normalized to surface area for the crustose coralline alga Porolithon sp. across the Southern Line Islands. Islands are ordered from south to north. Allophycocyanin (light pink), phycocyanin (pink), and phycoerythrin (dark pink) were measured on 2 subsamples of each individual (n = 4) per island. Data points are means of subsamples per individual. Significant differences in pigment concentrations across islands were determined for each pigment with Tukey’s HSD. Different letters represent significant differences at p < 0.05.