bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/449959

Taking a deeper look: Quantifying the differences in fish assemblages between shallow and mesophotic temperate rocky reefs

Williams, J.·Jordan, A.·Harasti, D.·Davies, P.·Ingleton, T.
View original source ↗Export metadata ↓

Abstract

The spatial distribution of a species assemblage is often determined by habitat and climate. In the marine environment, depth can become an important factor as degrading light leads to changes in the biological habitat structure. To date, much of the focus of ecological fish research has been based on reefs in less than 40 m with little research on the ecological role of mesophotic reefs. We deployed baited remote underwater stereo video systems (stereo-BRUVS) on temperate reefs in two depth categories: shallow (20-40m) and mesophotic (80-120m), off Port Stephens, Australia. Sites were selected using data collected by swath acoustic sounder to ensure stereo-BRUVS were deployed on reef. The sounder also provided rugosity, slope and relief data for each stereo-BRUVS deployment. Multivariate analysis indicates that there are significant differences in the fish assemblages between shallow and mesophotic reefs, primarily driven by Ophthalmolepis lineolatus and Notolabrus gymnogenis only occurring on shallow reefs and schooling species of fish that were unique to each depth category: Atypichthys strigatus on shallow reefs and Centroberyx affinis on mesophotic reefs. While shallow reefs had a greater species richness and abundance of fish when compared to mesophotic reefs, mesophotic reefs hosted the same species richness of fishery targeted species. Chrysophrys auratus (pink snapper) and Nemodactylus douglassii (grey morwong) are two highly targeted species in this region. While C. auratus was numerically more abundant on shallow reefs, mesophotic reefs provide habitat for larger fish. In comparison, N. douglassii were evenly distributed across all sites sampled. Generalized linear models revealed that depth and habitat type provided the most parsimonious model for predicting the distribution of C. auratus, while habitat type alone best predicted the distribution of N. douglassii. These results demonstrate the importance of mesophotic reefs to fishery targeted species and therefore have implications for informing the management of these fishery resources on shelf rocky reefs.

Source connections

Explore related subjects

ecologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Williams, J., Jordan, A., Harasti, D., Davies, P., Ingleton, T.. 2018-10-22. Taking a deeper look: Quantifying the differences in fish assemblages between shallow and mesophotic temperate rocky reefs. https://doi.org/10.1101/449959

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Restoration decisions in highly variable systems: Whether, when, and how to enhance kelp

In highly variable ecosystems, natural variability can obscure signals of decline that warrant intervention, as there is often a lack of long-term data needed to distinguish between declines that are transient and likely to recover naturally and those that would be permanent without intervention. Implementing restoration for a species involves deciding on a threshold condition at which to intervene, duration that this threshold needs to be met before intervening, life stages at introduction, and amounts to introduce. Current bull and giant kelp restoration efforts in California were spurred by persistent kelp loss that started in 2013 following a disease outbreak among predators of the primary herbivore and a marine heatwave. We asked how decisions about intervention cue, threshold, wait time, life stage at introduction, and amount affect population outcomes against a backdrop of environmental variability. We analyzed additional context-dependencies on grazing and climate intensity. To address these questions, we built and parameterized a stochastic stage-structured model for bull and giant kelp, in which we simulated kelp enhancement approaches under a range of grazing and climate scenarios. In a global sensitivity analysis of kelp enhancement decisions, we found that grazing intensity and life stages at introduction were the most influential determinants of kelp biomass and persistence outcomes. The kelp enhancement approach involving temporarily introduced juveniles restored the germ banks of bull and giant kelp, but the two species differed in their responses to that intervention, highlighting that optimal intervention approach is species-dependent. Waiting longer for natural recovery before intervening reduced total intervention effort but also reduced biomass recovery potential. These results support empirical findings from kelp enhancement pilot projects in California and highlight context-dependencies that inform restoration decision-making in kelp forests and other highly variable ecosystems.

ecology↗
bioRxiv2026

Indigenous communities' perceptions of ecosystem services of a montane forest ecosystem in Nigeria: Implications for restoration planning

Restoration of protected areas should aim to maximize outcomes for both biological conservation and local people's livelihoods. In rural Africa, livelihoods are inextricably linked to the provision of ecosystem services (ES) from natural resources, so that community-centred biodiversity conservation must be guided by local perceptions of ES. Our study examined perceptions of ES among eight communities within a 5-km radius of a Nigerian forest reserve characterized by an elevational gradient of 700 m, spanning montane forest, mid-elevation forest, and savannah. The montane forest is noted for its outstanding biodiversity value. We employed semi-structured interviews, focus group discussions and species-use inventories to characterize which ES are recognised, and their perceived importance. We also conducted an ethnobotanical assessment to document community uses of plants and classified the species as savannah or forest species. Across settlements, we observed a three-fold variation in the number of ES recognized, ranging from 6 to 20. Provisioning services, especially food, were ranked higher than regulating, cultural, or supporting services in most settlements. Notably, most provisioning services were from savannah, rather than forest species. Our study adds to growing data on indigenous knowledge about ecosystem services. Implications from these findings are that: i) Landscape-scale management should maintain a mosaic of montane forest and derived savannah to reflect prevailing provisioning needs while enhancing regulating and supporting services. ii) Restoration should prioritise tangible provisioning benefits (e.g., non-timber forest products, medicines and food) alongside regulating and supporting services to align with local priorities. iii) Given potential trade-offs between scientifically derived valuations (biodiversity, regulation) and stakeholder priorities, co-design of restoration objectives and adaptive governance are essential to secure local buy-in and on-going stewardship.

ecology↗
bioRxiv2026

Natural habitats are reservoirs of Fusarium lineages highly pathogenic on Triticum aestivum

Fungal plant diseases are a major cause of crop loss worldwide. Understanding the processes driving these diseases is therefore crucial to anticipate and control epidemics while improving crop yield production. Moreover, the new European Green Deal aims to reduce the use of pesticides, while, few alternatives are currently available on the market. There is therefore an urgent need to better track and anticipate fungal crop epidemics in the current context of fungicide reduction. In light of this, our study aims to understand Fusarium spill overs from non-agricultural habitats in order to better characterise potential non-host Fusarium reservoirs that may be implicated in the emergence of Fusarium diseases. To address this question, we isolated Fusarium lineages from natural populations of Brassica rapa. We characterised their phylogenomic affiliation and found that they display high diversity, with a population structure related to the locality of isolation. By inoculation assays, we identified Fusarium strains from non-agricultural habitats that were highly aggressive on wheat. In addition, we observed a strong effect of wheat variety on disease development. We monitored the Fusarium colonisation through a microscopy approach in both wheat and Brassica plants. We observed that while the fungus is mostly on root surface in Brassica plants, it spreads inter-cellularly in wheat roots with vascular colonisation in the wheat shoots. Finally, we showed that most aggressive Fusarium strains were isolated from Brittany, a French region where wheat is vastly cultivated.

ecology↗