Scenario planning with linked land-sea models inform where forest conservation actions will promote coral reef resilience

Abstract

We developed a linked land-sea modeling framework based on remote sensing and empirical data, which couples sediment export and coral reef models at fine spatial resolution. This spatially-explicit (60 × 60 m) framework simultaneously tracks changes in multiple benthic and fish indicators as a function of land-use and climate change scenarios. We applied this framework in Kubulau District, Fiji, to investigate the effects of logging, agriculture expansion, and restoration on coral reef resilience. Under the deforestation scenario, models projected a 4.5-fold sediment increase (>7,000 t. yr−1) coupled with a significant decrease in benthic habitat quality across 1,940 ha and a reef fish biomass loss of 60.6 t. Under the restoration scenario, models projected a small (<30 t. yr−1) decrease in exported sediments, resulting in a significant increase in benthic habitat quality across 577 ha and a fish biomass gain of 5.7 t. The decrease in benthic habitat quality and loss of fish biomass were greater when combining climate change and deforestation scenarios. We evaluated where land-use change and bleaching scenarios would impact sediment runoff and downstream coral reefs to identify priority areas on land, where conservation or restoration could promote coral reef resilience in the face of climate change.

Place‐based management can reduce human impacts on coral reefs in a changing climate

“…). In addition, we used existing wave data to represent mixing effects on the groundwater discharge, given circulation data was not available for our study sites (Delevaux ). Furthermore, species composition and relative abundance can affect the coral reef model performance and predictability of selected indicators (Pittman et al.…”

“…2018, Delevaux et al. ). The grid cells representing significant differences (α = 0.10) were reclassified to indicate where predictions were significantly different than present conditions under each scenario (Stamoulis et al.…”

“…2018, Delevaux et al. ). For the combined scenarios, we overlaid the coral reef areas of significant differences under land‐use and climate change scenarios and delineated areas of overlap, where both drivers could potentially interact.…”

“…The predictions were then used to produce maps of benthic and fish indicator distributions under each scenario (Delevaux et al. , Elith , Elith et al. ).…”

“…To do so, we calculated differences between predictions of coral reef indicators under the land‐use change, climate change, and combined scenarios, compared to present conditions with and without the marine closures (Delevaux et al. , Stamoulis et al. ).…”