Groundwater recharge, associated nutrient concentrations, and groundwater discharge flux (i.e. terrestrial drivers) at Ka‘ūpūlehu.

<p>(A) Groundwater recharge (m³.yr^-1). (B) Groundwater recharge N concentration (mg.L^-1) (with enlarged inset C). (D) Groundwater recharge P concentration (mg.L^-1) (with enlarged inset E). The modeled recharge (B) N and (D) P nutrient concentrations maps are overlaid with the GW survey points using the same color ramp for visual comparison. The R² and p-value compare the measured and modeled (E) N and (I) P concentrations at Ka‘ūpūlehu (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193230#pone.0193230.s008" target="_blank">S1 Fig</a> for linear regressions). (F) Modeled coastal groundwater flow (m³.yr^-1) coupled with (G) the SGD (m³.yr^-1). (H) Background, (I) human-derived, and (J) total N flux (kg.yr^-1) by flow tube combined with N marine discharge plume (kg.yr^-1). (K) Background, (L) human-derived, and (M) total P flux (kg.yr^-1) by flow tube combined with P marine discharge plume (kg.yr^-1)The R² and p-value compare the measured N and P concentrations (mg.L^-1) in coastal waters and modeled (J) N and (M) P marine discharge (kg.yr^-1) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193230#pone.0193230.s008" target="_blank">S1 Fig</a> for linear regressions).</p

Annual nutrient concentrations and flux of the groundwater background and land cover/use zones.

<p>Annual nutrient concentrations and flux of the groundwater background and land cover/use zones.</p

Linked land-sea modeling framework.

<p>Based on (A) climate, groundwater recharge, and recharge nutrient concentration data, (B) groundwater flow (m³.yr^-1) and nutrients concentrations (mg.L^-1) were modeled using MODFLOW and MT3D-MS. (C) Nutrient flux (kg.yr^-1) from anthropogenic drivers were added to the background nutrient flux. (D) A land-sea link was created using MODPATH. (E) The coastal discharge models used the groundwater flow (m³.yr^-1) and nutrients flux (kg.yr^-1) and GIS distance-based models to generate the terrestrial driver grid data. (F) The SWAN wave model and bathymetry data were coupled with (G) GIS-based models to generate the marine driver grid data. (H) The coral reef predictive models were calibrated on coral reef survey data. (I) Outputs were: (1) response curves, (2) maps of benthic (% cover) and fish (g.m^-2) indicators, and (3) a linked land-sea decision-support tool. (The wave model image in panel G is reprinted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193230#pone.0193230.ref066" target="_blank">66</a>] under a CC BY license, with permission from Charles Fletcher, original copyright 2009. Refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193230#pone.0193230.s001" target="_blank">S1 File</a>).</p

Study sites location.

<p>(A) Location of study sites on Kauaʻi and Hawaiʻi along the main Hawaiian Island chain, with island age and the direction of the prevailing north-east tradewinds and ocean swell indicated. Land use/cover and marine closure/fishing rest area are shown for (B) Hā‘ena and (C) Ka‘ūpūlehu.</p

Description of marine drivers.

<p>Description of marine drivers.</p

Groundwater recharge, associated nutrient concentrations, and groundwater discharge flux (i.e. terrestrial drivers) at Hā‘ena.

<p>(A) Groundwater recharge (m³.yr^-1). (B) Groundwater recharge N concentration (mg.L^-1) (with enlarged inset C). (D) Groundwater recharge P concentration (mg.L^-1) (with enlarged inset E). The modeled recharge (B) N and (D) P nutrient concentrations maps are overlaid with the GW survey points using the same color ramp for visual comparison. (F) Modeled coastal groundwater flow (m³.yr^-1) coupled with (G) the SGD (m³.yr^-1). (H) Background, (I) human-derived, and (J) total N flux (kg.yr^-1) by flow tube combined with N marine discharge plume (kg.yr^-1). (K) Background, (L) human-derived, and (M) total P flux (kg.yr^-1) by flow tube combined with P marine discharge plume (kg.yr^-1)The R² and p-value compare the measured N and P concentrations (mg.L^-1) in coastal waters and modeled (J) N and (M) P marine discharge (kg.yr^-1) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193230#pone.0193230.s008" target="_blank">S1 Fig</a> for linear regressions).</p

Observed and predicted distribution of coral reef indicators at Hā‘ena and Ka‘ūpūlehu.

<p>Benthic indicators at (A-D) Hā‘ena and (I-L) Ka‘ūpūlehu are measured in % cover and the fish indicators at (E-H) Hā‘ena and (M-P) Ka‘ūpūlehu are measured in g.m^-2. The predicted maps are overlaid with the survey points using the same color ramp for visual comparison, combined with the R² and p-values.</p

Model domains and land-sea link.

<p>The groundwater (GW) model domain at (A) Hā‘ena (15x15 m) overlaps with the Wainiha Aquifer. The GW model domain at (B) Ka‘ūpūlehu (50x50 m) was divided into 4 zones (Keauhou upland and lowland, Ka‘ūpūlehu upland and lowland) and spreads across the Kīholo and Keauhou Aquifers and bisected by a rift line. In the coastal zone, the groundwater model domain was sub-divided into narrow (~200 m) flow tubes ending at pour points along the shoreline to spatially link the groundwater model outputs to SGD. Reef surveys were provided by FERL at (C) Hā‘ena and TNC at (D) Ka‘ūpūlehu. Based on the depth of coral reef surveys, the coral reef (CR) model domain (60x60 m) extended from the shoreline to –15 m at Hā‘ena and –22 m at Ka‘ūpūlehu.</p

dbRDA of the coral reef communities.

<p>Ordination plot illustrating the relationship between terrestrial and marine drivers that best explain the variation of benthic and fish indicators in Hā‘ena and Kaʻūpūlehu. The dbRDA vectors show the drivers explaining a significant proportion of the variation. The drivers differentiating the coral reef communities at Hā‘ena from Ka‘ūpūlehu are: wave power, distance to shore, depth, groundwater (H₂O) and nutrients (N and P).</p

Study site attributes.

<p>Study site attributes.</p