Michael Travers

eDNA metabarcoding survey reveals fine‐scale coral reef community variation across a remote, tropical island ecosystem

Publisher: Wiley

Date: 03-2020

DOI: 10.1111/MEC.15382

Large‐scale eDNA metabarcoding survey reveals marine biogeographic break and transitions over tropical north‐western Australia

Publisher: Wiley

Date: 24-01-2021

DOI: 10.1111/DDI.13228

Abstract: Environmental DNA (eDNA) metabarcoding has demonstrated its applicability as a highly sensitive biomonitoring tool across small spatial and temporal scales in marine ecosystems. However, it has rarely been tested across large spatial scales or biogeographical barriers. Here, we scale up marine eDNA metabarcoding, test its ability to detect a major marine biogeographic break and evaluate its use as a regional biomonitoring tool in Australia. North‐western Australia (NWA). We applied metabarcoding assays targeting the mitochondrial 16S rRNA and CO1 genes to 284 surface seawater eDNA s les collected from 71 mid‐shelf, inshore, coastal and nearshore estuarine sites over 700 km of the NWA coastline. Metabarcoding detected a wide range of bony fish (404 taxa), elasmobranchs (44) and aquatic reptiles (5). We detected bioregional and depth differentiation within inshore bony fish communities. These findings support the presence of a marine biogeographic break, which is purported to occur in the vicinity of Cape Leveque, demarcating the border between the Kimberley and Canning bioregions. Inshore bony fish and elasmobranch communities, as well as coastal bony fish assemblages, were additionally found to differ between the South and North Kimberley regions suggesting previously unrecognized subregional differentiation amongst these taxa. The overall compositional data have been used to update distribution information for a number of endangered, elusive and data‐deficient taxa, including sawfish (family: Pristidae), northern river shark ( Glyphis garricki ) and wedgefish (genus: Rhynchobatus ). eDNA metabarcoding demonstrated a high level of sensitivity that was able to discern fine‐scale patterns across the large‐scale, remote and oceanographically complex region of North‐western Australia. Importantly, this study highlights the potential of integrating broad‐scale eDNA metabarcoding alongside other baseline surveys and long‐term monitoring approaches, which are crucial for the sustainable management and conservation of marine bio ersity in this unique marine region.

A field and video annotation guide for baited remote underwater stereo-video surveys of demersal fish assemblages

Publisher: Wiley

Date: 24-09-2020

DOI: 10.1111/2041-210X.13470

Cryptic lineages in the Wolf Cardinalfish living in sympatry on remote coral atolls

Publisher: Elsevier BV

Date: 03-2019

DOI: 10.1016/J.YMPEV.2018.12.001

Abstract: Coral reef health and bio ersity is under threat worldwide due to rapid climate change. However, much of the inter- and intra-specific ersity of coral reefs are undescribed even in well studied taxa such as fish. Delimiting previously unrecognised ersity is important for understanding the processes that generate and sustain bio ersity in coral reef ecosystems and informing strategies for their conservation and management. Many taxa that inhabit geographically isolated coral reefs rely on self-recruitment for population persistence, providing the opportunity for the evolution of unique genetic lineages through ergent selection and reproductive isolation. Many such lineages in corals and fish are morphologically similar or indistinguishable. Here, we report the discovery and characterisation of cryptic lineages of the Wolf Cardinalfish, Cheilodipterus artus, from the coral atolls of northwest Australia using multiple molecular markers from mitochondrial (CO1 and D-loop) and nuclear (microsatellites) DNA. Concordant results from all markers identified two highly ergent lineages that are morphologically cryptic and reproductively isolated. These lineages co-occurred at daytime resting sites, but the relative abundance of each lineage was strongly correlated with wave exposure. It appears, therefore, that fish from each lineage are better adapted to different microhabitats. Such cryptic and ecologically based ersity appears to be common in these atolls and may well aid resilience of these systems. Our results also highlight that underwater surveys based on visual identification clearly underestimate bio ersity, and that a taxonomic revision of the Cheilodipterus genus is necessary.

Effects of human footprint and biophysical factors on the body-size structure of fished marine species

Publisher: Wiley

Date: 27-07-2022

DOI: 10.1111/COBI.13807

Abstract: Marine fisheries in coastal ecosystems in many areas of the world have historically removed large‐bodied in iduals, potentially impairing ecosystem functioning and the long‐term sustainability of fish populations. Reporting on size‐based indicators that link to food‐web structure can contribute to ecosystem‐based management, but the application of these indicators over large (cross‐ecosystem) geographical scales has been limited to either fisheries‐dependent catch data or er‐based methods restricted to shallow waters ( m) that can misrepresent the abundance of large‐bodied fished species. We obtained data on the body‐size structure of 82 recreationally or commercially targeted marine demersal teleosts from 2904 deployments of baited remote underwater stereo‐video (stereo‐BRUV). S ling was at up to 50 m depth and covered approximately 10,000 km of the continental shelf of Australia. Seascape relief, water depth, and human gravity (i.e., a proxy of human impacts) were the strongest predictors of the probability of occurrence of large fishes and the abundance of fishes above the minimum legal size of capture. No‐take marine reserves had a positive effect on the abundance of fishes above legal size, although the effect varied across species groups. In contrast, sublegal fishes were best predicted by gradients in sea surface temperature (mean and variance). In areas of low human impact, large fishes were about three times more likely to be encountered and fishes of legal size were approximately five times more abundant. For conspicuous species groups with contrasting habitat, environmental, and biogeographic affinities, abundance of legal‐size fishes typically declined as human impact increased. Our large‐scale quantitative analyses highlight the combined importance of seascape complexity, regions with low human footprint, and no‐take marine reserves in protecting large‐bodied fishes across a broad range of species and ecosystem configurations.

Sympatric species of coral trout (Plectropomus) show contrasting patterns of genomic structure across isolated atoll reefs

Publisher: Springer Science and Business Media LLC

Date: 17-10-2023

DOI: 10.1007/S11160-023-09809-Z

Seascape genomics reveals fine-scale patterns of dispersal for a reef fish along the ecologically divergent coast of Northwestern Australia

Publisher: Wiley

Date: 28-10-2017

DOI: 10.1111/MEC.14352

Abstract: Understanding the drivers of dispersal among populations is a central topic in marine ecology and fundamental for spatially explicit management of marine resources. The extensive coast of Northwestern Australia provides an emerging frontier for implementing new genomic tools to comparatively identify patterns of dispersal across erse and extreme environmental conditions. Here, we focused on the stripey snapper (Lutjanus carponotatus), which is important to recreational, charter-based and customary fishers throughout the Indo-West Pacific. We collected 1,016 L. carponotatus s les at 51 locations in the coastal waters of Northwestern Australia ranging from the Northern Territory to Shark Bay and adopted a genotype-by-sequencing approach to test whether realized connectivity (via larval dispersal) was related to extreme gradients in coastal hydrodynamics. Hydrodynamic simulations using CONNIE and a more detailed treatment in the Kimberley Bioregion provided null models for comparison. Based on 4,402 polymorphic single nucleotide polymorphism loci shared across all in iduals, we demonstrated significant genetic sub ision between the Shark Bay Bioregion in the south and all locations within the remaining, more northern bioregions. More importantly, we identified a zone of admixture spanning a distance of 180 km at the border of the Kimberley and Canning bioregions, including the Buccaneer Archipelago and adjacent waters, which collectively experiences the largest tropical tidal range and some of the fastest tidal currents in the world. Further testing of the generality of this admixture zone in other shallow water species across broader geographic ranges will be critical for our understanding of the population dynamics and genetic structure of marine taxa in our tropical oceans.

Local Environmental Context Structures Animal-Habitat Associations Across Biogeographic Regions

Publisher: Springer Science and Business Media LLC

Date: 09-06-2021

DOI: 10.1007/S10021-021-00651-7

Increased connectivity and depth improve the effectiveness of marine reserves

Publisher: Wiley

Date: 20-05-2021

DOI: 10.1111/GCB.15635

Abstract: Marine reserves are a key tool for the conservation of marine bio ersity, yet only ~2.5% of the world's oceans are protected. The integration of marine reserves into connected networks representing all habitats has been encouraged by international agreements, yet the benefits of this design has not been tested empirically. Australia has one of the largest systems of marine reserves, providing a rare opportunity to assess how connectivity influences conservation success. An Australia‐wide dataset was collected using baited remote underwater video systems deployed across a depth range from 0 to 100 m to assess the effectiveness of marine reserves for protecting teleosts subject to commercial and recreational fishing. A meta‐analytical comparison of 73 fished species within 91 marine reserves found that, on average, marine reserves had 28% greater abundance and 53% greater biomass of fished species compared to adjacent areas open to fishing. However, benefits of protection were not observed across all reserves (heterogeneity), so full subsets generalized additive modelling was used to consider factors that influence marine reserve effectiveness, including distance‐based and ecological metrics of connectivity among reserves. Our results suggest that increased connectivity and depth improve the aforementioned marine reserve benefits and that these factors should be considered to optimize such benefits over time. We provide important guidance on factors to consider when implementing marine reserves for the purpose of increasing the abundance and size of fished species, given the expected increase in coverage globally. We show that marine reserves that are highly protected (no‐take) and designed to optimize connectivity, size and depth range can provide an effective conservation strategy for fished species in temperate and tropical waters within an overarching marine bio ersity conservation framework.

Murdoch University

Location: Australia

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Government Of Western Australia Department Of Primary Industries And Regional Development

Location: Australia

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