Januchowski-Hartley, F. A.

bioRxiv2026

Algal turf sediment dynamics across the Florida Reef Tract

Algal turfs and their associated sediments are dominant components of many degraded reefs, where they mediate key ecosystem processes. However, the quantification of algal turfs and their sediments across reef shelves is limited outside Indo-Pacific reef systems. We quantified algal turf length, sediment loads, and sediment grain size distribution across four reef positions (nearshore, inner, middle, and outer) at three locations along the northern Florida Reef Tract (FRT). Sediment loads were positively associated with algal turf length and generally declined moving offshore. Nearshore reefs supported algal turfs that were both 1.6-fold longer and contained 1.6-fold higher sediment loads than on outer reefs, while sediment composition shifted toward finer grain sizes offshore. Nevertheless, regardless of reef position, all algal turfs had high sediment loads ranging from 1,445 to 16,639 g m-2. Our findings suggest that cross-shelf patterns in algal turf sediment dynamics are present on Western Atlantic reefs and reveal that long sediment-laden algal turfs dominate on the FRT. These results highlight the pervasive nature of sediment-laden algal turfs on degraded reefs and emphasize the need to monitor and manage their expansion on reefs subject to chronic coastal development and climate-driven disturbance.

ecology↗

bioRxiv2023

Downscaling global reference points to assess the sustainability of local fisheries

Multispecies coral reef fisheries are typically managed by local communities who often lack research and monitoring capacity, which prevents estimation of well-defined sustainable reference points to perform locally relevant fishery assessments. Recent global advances in modelling coral reef fisheries have developed pathways to use environmental indicators to estimate multispecies sustainable reference points. These global reference points are a promising tool for assessing data-poor reef fisheries but need to be downscaled to be relevant to resource practitioners. Here, using a small-scale multispecies reef fishery from Papua New Guinea, we estimate sustainable reference points and assess the sustainability of the fishery by integrating global-scale analyses with local-scale environmental conditions, fish catch, reef area, standing biomass estimates, and fishers perceptions. We found that assessment results from global models applied to the local context of our study location provided results consistent with local fishers perceptions. Specifically, our downscaled results suggest that the fishing community is overfishing their reef fish stocks (i.e., catching more than can be sustained) and stocks are below BMMSY (i.e., below biomass levels that maximize production), making the overall reef fishery unsustainable. These results were consistent with fisher perceptions that reef fish stocks were declining in abundance and mean fish length, and that they had to spend more time finding fish. Our downscaled site-level assessment reveals severe local resource exploitation, whose dynamics are masked in national-scale assessments, emphasizing the importance of matching assessments to the scale of management. More broadly, our study shows how global reference points can be applied locally when long-term data are not available, providing baseline assessments for sustainably managing previously un-assessed multispecies reef fisheries around the globe.

ecology↗