DOI: 10.5061/dryad.2d0g778
title: Data from: Projecting the recovery of a long-lived deep-sea octocoral species after the Deepwater Horizon oil spill using structured population models

description: 1. Deep-water coral communities are hotspots of diversity and biomass in
 the deep sea. Most deep-sea coral species are long-lived and slow-growing,
 and are thus expected to recover slowly after disturbance. A better
 understanding of the recovery potential of these organisms is necessary to
 make appropriate management decisions. 2. We used data from high
 resolution monitoring of individual coral colonies that were impacted by
 the Deepwater Horizon oil spill (April 2010) to parameterise and validate
 an annual, impact-dependent, state-structured matrix model to estimate the
 time to recovery for each coral colony. We projected the dynamics of three
 branch states: visibly healthy, unhealthy and hydroid-colonized. Although
 we implicitly included branch loss in the model, we focused on the
 short-term return of extant, damaged, branches to a visibly healthy state
 and did not consider the far longer-term re-growth of lost branches. 3.
 Our model estimates that, depending on the initial level of impact, corals
 impacted by the spill will take up to three decades to recover to a state
 where all remaining branches appear healthy, though the majority of corals
 are projected to reach that state within a decade. By that time, some of
 these colonies will have lost a significant number of branches, leading to
 approximately 10% reduction in total biomass at all impacted sites. 4.
 Overall, our model overestimates recovery, but branch loss estimates were
 reliable. Thus, the available growth rate data suggest that hundreds of
 years may be necessary for impacted communities to grow back to their
 initial biomass. 5. Policy implications. Our study quantifies the very
 slow recovery rate of deep-sea corals and demonstrates the imperative of
 prioritizing a precautionary approach for these deep-sea ecosystems over
 restoration after the fact. As anthropogenic pressure on the deep sea is
 likely to increase, we suggest the establishment of coral-monitoring sites
 implemented as part of Marine Protected Areas to limit and detect impact
 to deep-sea corals. Furthermore, estimates from our model may be used to
 plan short- and longer-term monitoring programmes after impact and to
 provide a timeline for policy.09-Feb-2018
description: R script for the
 modelModel_script.RTransition values for healthy branches (2011-2015)All values were estimated from digitized images of individual coral colonies. Abbreviations: Coral (individual colony identifier), Total (total number of branches), Total nv (total number of healthy branches), nv_to_nv, nv_to_nh, nv_to_hy (number of healthy branches that transitioned to healthy, unhealthy or hydroid-colonized, respectively, Impact (total visible impact proportion), Size (total coral size (m)), Site, Year (imaging year).nv_counts_size_novn_MC294_11-15.csvTransition values for unhealthy branches (2011-2015)All values were estimated from digitized images of individual coral colonies. Abbreviations: Coral (individual colony identifier), Total (total number of branches), Total nh (total number of unhealthy branches), nh_to_nv, nh_to_nh, nh_to_hy (number of unhealthy branches that transitioned to healthy, unhealthy or hydroid-colonized, respectively, Impact (total visible impact proportion), Size (total coral size (m)), Site, Year (imaging year).nh_counts_size_novn_MC294_11-15.csvTransition values for branches colonized by hydroids (2011-2015)All values were estimated from digitized images of individual coral colonies. Abbreviations: Coral (individual colony identifier), Total (total number of branches), Total hy (total number of branches colonized by hydroids), hy_to_nv, hy_to_nh, hy_to_hy (number of hydroid-colonized branches that transitioned to healthy, unhealthy or hydroid-colonized, respectively, Impact (total visible impact proportion), Size (total coral size (m)), Site, Year (imaging year).hy_counts_size_novn_MC294_11-15.csvNumber of branches in each state in 2011Number of branches in each state in 2011 (initial conditions) for every coral colony at MC 294, MC 297 and MC 344.initial_impact_counts.csvCoral size in 2011Size (m) of every coral colony at MC 294, MC 297 and MC 344.initial_size.csvAverage coral size used for model simulationsAverage coral size (m) calculated based on coral colonies from MC 294, MC 297 and MC 344.initial_size_simulations_100_170br.csvProportions of unhealthy and hydroid-colonized branchesProportions of unhealthy and hydroid-colonized branches for every coral colony at MC 294, MC 297 and MC 344.impact_values.csv