DOI: 10.25903/54g5-fg77
title: Data from: Inshore coral reef sediment and turf dynamics unaffected by canopy-forming macroalgae

description: <p><b>Background [Extract from Related publication]: </b>Nearshore coral reefs face increasing abundance of fleshy macroalgae, an indicator of degradation and threat to ecosystem functioning. Removal of macroalgae is proposed to assist coral recovery, though the ecological and physical impacts have not been studied. Nearshore reefs are also confronted with sedimentation stress, influenc- ing reef dynamics including algal turfs, with flow-on impacts to coral recruitment, fish diets, and trophic cas- cades. In this study, the interplay between macroalgal canopies, sediment deposition and algal turf environments was investigated on the nearshore Great Barrier Reef. Removal of fleshy macroalgae over two years had no signif- icant effect on the amount or composition of sediment deposited on proxy coral (SedPods) and algal turf (Turf- Pods) surfaces, nor was the height of algal turfs impacted.</p>

<p><b>Methods [Extract]:</b> This study builds upon a long-term project investigating the impacts of macroalgae removal on the fringing coral reefs of Yunbenun (Magnetic Island), on the central inshore region of Australia’s Great Barrier Reef, and described previously in Smith et al. (2023, 2022). Briefly, twelve 25 m2 (5 x 5 m) experimental plots were established in two eastward facing bays (Arthur and Florence), with six plots designated as controls (referred to herein as ‘control plots’) and the remaining six treatment plots periodically cleared of fleshy macroalgae (referred to herein as ‘removal plots’; Supplementary Figure 1). Within the timeline of this study, macroalgae were manually removed from removal plots in July and October 2020, and April, July, and October 2021. Net sediment deposition was measured using SedPods and TurfPods, which emulate coral and algal turf substrate, respectively. Samples were then wet sieved through a 1.4 mm stainless steel mesh, retaining all material less than 1.4 mm. A subsample of known volume (200 ml for SedPods, 20 ml for TurfPods) processed via vacuum filtration using a pre-weighed 42 mm glass microfibre filter (Whatman, USA) and dried at 105°C for 24 h to yield total dry mass. The residual filter was then combusted at 550°C for 1 h in a Carbolite muffle furnace according to APHA Standard Method 2540E and re-weighed to yield the mass of the non-volatile solid component (American Public Health Association, 2018). The weight lost upon ignition denotes the volatile solid component in the deposited sediment, approximating the proportion of organic material in the sample. The distribution of grain sizes was assessed via laser diffraction. The three replicate samples for each pod type in each plot were merged and treated with the common dispersal agent Calgon. The merged sample was then sonicated for 10 minutes immediately prior to analysis to separate flocculated particles and analyzed via laser diffraction using a Malvern Mastersizer 3000 particle size analyzer with a lens range of 0.01–3500 μm (refractive index: 1.52, samples ultrasonically dispersed at 15% power for 30 seconds prior to measurement) to yield grain size distribution for each sample. Algal turf height was measured to quantify sediment trapping potential and productivity of the EAM. Using plastic Vernier calipers, algal turf height was recorded at 10 haphazardly selected locations within three 1 m2 quadrats within each 25 m2 experimental plot. Two temperature loggers (HOBO MX2202) were installed in each bay for the duration of the study. Publicly available water temperature data for Yunbenun from loggers installed by the Australian Institute of Marine Science were also used to supplement water temperature data throughout the study period. Hydrodynamic variation in each bay was measured using a suite of current meters (Marotte HS-1; 6 in Arthur Bay, 7 in Florence Bay), deployed throughout the period November 2020 to February 2021. Additional short-term deployments were undertaken during each pod deployment (dates listed above) to enhance spatial coverage. </p>

<p><b>This data record contains:</b>
<ul>
<li>BIOMASS.csv – KGs of algae removed from experimental plots </li>
<li>currentmeters_deposition.csv – current meter deployment information, current speeds, and total deposition data for SedPods and TurfPods</li>
<li>PSA_ANALYSIS.csv – particle size data generated from MasterSizer</li>
<li>PSA_supp_means_VALUES.csv – mean and merged particle size sample data from MasterSizer</li>
<li>SEDIMENTS_DRYWEIGHTS.csv – dry weight and organic content data from SedPods and TurfPods</li>
<li>temp_clevelandbay_aims.csv – sea temperature data extracted from the publicly available AIMS database</li>
<li>TEMPLIGHT.csv – temperature and light data from HOBO loggers</li>
<li>TURFS.csv – turf height data from experimental plots</li>
<li>Sediments-analysis.Rmd – the R code used to process and analyse all datasets</li>