DOI: 10.5061/dryad.j0zpc86c2
title: Rubble Biodiversity Samplers (RUBS): 3D-printed coral models to standardise biodiversity censuses

description: 1. To ensure standardised, quantitative and repeatable methodologies,
 marine ecologists have engineered a range of artificial units to survey
 benthic communities with varying designs depending on target taxa, life
 history stage and habitat. In tropical ecosystems, autonomous units have
 typically lacked microhabitat complexity (e.g. planar tiles), short-term
 efficacy (&gt; 1 y deployment) and/or a truly standardised design to
 sample cryptobenthic diversity. 2. Coral rubble is characterised by high
 microhabitat complexity, which is unresolved in sampling efforts. Yet,
 rubble can support the greatest density and diversity of metazoan taxa. 3.
 We engineered Rubble Biodiversity Samplers (RUBS) as a dismantlable
 lightweight 3D-printed model to standardise cryptobenthic biodiversity
 sampling. 4. We demonstrate the effectiveness of RUBS with preliminary
 results from short-term (1–14 days) deployments in Palau, Western
 Micronesia. 5. RUBS uphold the microhabitat complexity inherent in coral
 rubble (~50% interstitial space) and provide an effective and efficient
 methodology to sample cryptobenthic fauna, which could be applied in
 comparative studies. 6. The RUBS concept provides a platform for the
 broader implementation of 3D-printed models in marine ecology to overcome
 issues of standardisation regardless of habitat type.
description: PRINTING: The 3D-printed RUBS model consisted of four independent
 layers of artificial coral rubble designed to be stacked and joined using
 bolts and wingnuts through intentionally engineered holes. Each layer (ca.
 140 x 90 x 20 mm) was created in Meshmixer (Version 3.5.474) by dissecting
 an existing branching coral (<i>Acropora</i>) design (https://www.thingiverse.com/thing:795094). Replicate RUBS models were printed using grey polylactic acid (PLA) filament in Fused Deposition Modelling printers (Flashforge Guider IIs) at UQ Innovate (University of Queensland, Australia), which was relatively cost effective (~AU$15 RUBS<sup>-1</sup>). FIELD COLLECTION: RUBS were deployed in shallow (1–2 m depth) coral rubble habitat in Palau, Western Micronesia (7˚16’4.3” N, 134˚27’7.6” E), November­–December 2019. The site was accessed by boat and fieldwork conducted on snorkel. Sixteen RUBS units were used on rotation, deployed with a small weight attached to the base in novel depressions (~8 cm depth) made carefully in the rubble by hand. For retrieval, RUBS were lifted from their depressions directly into individual plastic collection bags underwater and transferred in buckets to the Palau International Coral Reef Center (PICRC) where they were processed immediately. All fauna &gt;250 µm were measured and identified (namely to the family level) using a dissecting microscope. NATURAL RUBBLE COMPARISON: Small plastic mesh (5 x 5 mm) baskets were engineered to be the same dimensions as the RUBS (14 x 9 x 8 cm). Baskets were carefully filled with rubble <i>in situ</i> and embedded into novel depressions for 1–3 days before retrieval. Retrieval and sampling procedures were as for RUBS, above.
description: The data are in two parts: motile cryptofauna collected from (1)
 RUBS and (2) rubble-filled baskets. The columns 'wdv' indicates
 water displacement volume of the RUBS and rubble baskets for density
 calculations.  The RUBS models can be found at: https://www.thingiverse.com/thing:4176644/files