Assessing the effects of engineered oyster reefs on shoreline change using drones

IntroductionCoastal infrastructure and property, as well as intertidal wetlands, are increasingly being threatened by shoreline erosion; a consequence of human activities and climate change. Nature-based solutions, such as intertidal engineered oyster reefs, can reduce erosion and promote sediment accretion, thereby promoting the restoration and persistence of salt marshes and preventing the loss of coastal lands. Engineered oyster reef substrate and design options have rapidly expanded in the last decade, yet our understanding of how these approaches influence ecosystems and intertidal morphology is limited. Drones (or small uncrewed aerial systems [sUAS]) coupled with structure-from-motion (SfM) photogrammetry have recently been suggested as a low-cost method that offers optimal spatial coverage, fine-scale resolution, and high vertical accuracy for monitoring changes around living shorelines.MethodsWe evaluated how using different vertical and horizontal uncertainty thresholds for detection of drone-based shoreline change can influence interpretation of performance of engineered oyster reefs on coastal morphology and vegetation. We monitored three sites with engineered oyster reefs installed in 2020 and one reference site located on Carrot Island along Taylor Creek in Beaufort, NC, USA. ResultsComparisons of the Digital Elevation Models (DEMs) and orthomosaics derived from the drone imagery revealed all sites saw marsh edge retreat from 2022 to 2023 (2-3 years post-restoration), and all sites except one low-relief oyster reef site saw elevation loss. Elevation loss was highest at the control site, but marsh edge retreat was highest at one of the engineered oyster reefs.DiscussionWhile horizontal thresholds did not yield statistically different results, vertical thresholds did. Our results support using a 95% confidence interval for conservative volumetric estimates and recommend that future studies consider aligning uncertainty thresholds with monitoring goals and timelines

Intra-articular therapy with recombinant human GDF5 arrests disease progression and stimulates cartilage repair in the rat medial meniscus transection (MMT) model of osteoarthritis

SummaryObjectiveInvestigation of osteoarthritis (OA) risk alleles suggests that reduced levels of growth and differentiation factor-5 (GDF5) may be a precipitating factor in OA. We hypothesized that intra-articular recombinant human GDF5 (rhGDF5) supplementation to the OA joint may alter disease progression.MethodsA rat medial meniscus transection (MMT) joint instability OA model was used. Animals received either one intra-articular injection, or two or three bi-weekly intra-articular injections of either 30 μg or 100 μg of rhGDF5 beginning on day 21 post surgery after structural pathology had been established. Nine weeks after MMT surgery, joints were processed for histological analysis following staining with toluidine blue. Control groups received intra-articular vehicle injections, comprising a glycine-buffered trehalose solution. OA changes in the joint were evaluated using histopathological end points that were collected by a pathologist who was blinded to treatment.ResultsIntra-articular rhGDF5 supplementation reduced cartilage lesions on the medial tibial plateau in a dose-dependent manner when administered therapeutically to intercept OA disease progression. A single 100 μg rhGDF5 injection on day 21 slowed disease progression at day 63. A similar effect was achieved with two bi-weekly injections of 30 μg. Two bi-weekly injections of 100 μg or three bi-weekly injections of 30 μg stopped progression of cartilage lesions. Importantly, three biweekly injections of 100 μg rhGDF5 stimulated significant cartilage repair.ConclusionsIntra-articular rhGDF5 supplementation can prevent and even reverse OA disease progression in the rat MMT OA model. Collectively, these results support rhGDF5 supplementation as an intra-articular disease modifying OA therapy