Australian Marine Park Research Articles

Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean

Remote Underwater Video Confirms the Presence of Dugongs (Dugong dugon) at Ashmore Reef Australian Marine Park in the Eastern Indian Ocean

Connecting the dots: Applying multispecies connectivity in marine park network planning

Marine ecosystems are highly dynamic, and their connectivity is affected by a complex range of biological, spatial, and oceanographic factors. Incorporating connectivity as a factor in the planning and management of marine protected areas (MPAs) is important yet challenging. Here, we implemented a novel integrative framework that uses intraspecific genetic and genomic data for multiple marine species to characterise connectivity across a recently established South Australian MPA network. We generated connectivity networks, estimated cross-species concordance of connectivity patterns, and tested the impact of key spatial and oceanographic factors on each species. Connectivity patterns varied markedly among species, but were most correlated among those with similar dispersal strategies. Ordination analyses revealed significant associations with both waterway distances and oceanographic advection models. Notably, waterway distances provided better predictive power in all-species combined analyses. We extended the practical relevance of our findings by employing spatial prioritisation with Marxan, using node values derived from both genetic and geographic connectivity networks. This allowed the identification of several priority areas for conservation, and substantiated the initial decision to employ spatial distance as a proxy for biological connectivity for the design of the South Australian marine park network. Our study establishes a baseline for connectivity monitoring in South Australian MPAs, and provides guidelines for adapting this framework to protected networks elsewhere in the world.

Comparative assessment of eDNA metabarcoding and longline deployments for elasmobranch surveying across a large tropical marine park network

Abstract Medium‐ to large‐scale marine protected areas (MPAs) are playing an increasingly important role in global marine biodiversity conservation. A key question is “how do we collect relevant data on biodiversity and population trends to inform their design and measure success?” This question is particularly relevant for marine taxa that are difficult to survey, such as sharks and rays, and where populations may occur over vast areas. Environmental DNA (eDNA) metabarcoding has proven to be an effective sampling method and may provide a solution to these challenges; however, it remains unclear how its sampling effectiveness compares with traditionally used methods for elasmobranch surveying. Here, we directly compared the efficacy of eDNA metabarcoding and demersal longline deployments to survey elasmobranchs across 31 sites over a 55,000 km2 area of the Kimberley and Roebuck Australian Marine Parks in Australia's North‐west Marine Parks Network. In total, we documented 49 unique elasmobranch taxa, 36 of which were detected by eDNA and 32 (from a total of 815 captured sharks) by longline. A combined approach yielded over 34% more elasmobranch taxa than either method alone. Site community compositions varied between the two survey methods; notably eDNA was able to detect species from outside of the immediate sampling area, although this was still consistent with a detection radius of a few kilometres, highlighting a particular use in rugose reef habitats where it is difficult to deploy longlines. In investigating the quantitative use of eDNA data, we report that eDNA metabarcoding read abundance (count) data was poorly correlated with longline aggregate catch (count and biomass) data across raw, relative and rank abundance measures. However, we found that in multivariate analyses, both binary (presence–absence) and abundance (after square‐root transformation) datasets produced highly similar ordination patterns, largely segregating method (eDNA vs. longline), followed by latitude and depth. Lastly, we identified required levels of eDNA replication and longline deployments to maximize captured elasmobranch diversity. This study sets an integrated, georeferenced baseline and long‐term monitoring approach for the management and conservation of elasmobranch diversity within this unique marine park network.

Geomorphometric maps of Australia’s Marine Park estate and their role in improving the integrated monitoring and management of marine ecosystems

The loss of marine biodiversity is a major global issue that needs to be prioritised. In Australia, a considerable proportion (48%) of its Exclusive Economic Zone is dedicated to marine protected areas. To effectively manage this network of marine protected areas Australia has recently introduced a Management Effectiveness system. This system is designed to identify, monitor, and manage natural values and the various activities and pressures affecting the Australian Marine Parks (AMPs). Key to this approach is the identification and accurate mapping of the location of these values and pressures acting on the seabed. The AusSeabed program is a national initiative in Australia aimed at improving access to bathymetric data and coordinating efforts to collect such data in Australian waters. This manuscript proposes a novel systematic processing method to create detailed and scalable geomorphometric maps from AusSeabed’s bathymetric data holdings, intended as a standard operating procedure for initial bathymetric data interpretation in the AMPs. Utilising this workflow, we produce seafloor geomorphometry maps across 37 AMPs within which sufficient bathymetric data has been collected. These maps can be used 1) for predictive mapping of biological assemblages; 2) in field sampling design for the collection of ‘ground truthing’ data (e.g. underwater imagery and sediment samples) to validate habitat maps from bathymetric datasets; and 3) as input datasets for subsequent geomorphological mapping with a deeper understanding of seafloor processes. This research highlights the importance of robust geomorphometry classification standards to ensure consistency in mapping Australia’s marine estate in preparation for the Decade of Oceans plans. The Seamap Australia program provides a stepwise approach to advancing Australia’s national collection of bathymetric data into derived products that can enable habitat mapping of Australian waters, providing a foundational tool for the adaptive management of AMPs.

Sharks checking in to the sponge hotel: First internal use of sponges of the genus Agelas and family Irciniidae by banded sand catsharks Atelomycterus fasciatus.

Trawl surveys within and surrounding two northwestern Australian marine parks revealed banded sand catsharks Atelomycterus fasciatus (family Atelomycteridae) taking refuge within large sponges of the family Irciniidae (Demospongiae: Dictyoceratida) and the genus Agelas (Demospongiae: Agelasida: Agelasidae). Five sponges contained a total of 57 A. fasciatus, comprising both sexes and both immature and mature individuals ranging from 102 to 390 mm total length (TL). In the same surveys, only five A. fasciatus were captured unassociated with sponges, suggesting that sponges are an important microhabitat for A. fasciatus and may provide a daytime refuge from predators. A southerly range extension is also reported for this species.

Assessment of Governance and Ecological Status of Terengganu Marine Park, Malaysia: Toward Marine Spatial Planning

Terengganu Marine Parks (TMP) is a 591.37 km2 marine protected area. TMP are popular tourist destinations that significantly generate revenue to the government and local businesses through tourism sector. However, the anthropogenic activities have contributed to TMP’s declining ecosystem health, particularly the coral reefs. Therefore, a sustainable ecosystem-based management is required to maintain the ecosystem. In this study, we identify issues related to the marine park’s governance, development on islands, tourist activities and coral health status in the TMP for assessing potential management strategy for conserving the ecosystem. The findings on management in TMP found that there is an overlapping in managing the marine park between the federal and state government. Unintegrated development to accommodate rising number of tourist and their activities in the marine parks are identified as the factors contributing towards degradation of the ecosystems. Relatively, reef areas close to these local pressures are in ‘poor’ condition, indicating that threats arising from the activities affecting the marine ecosystem. Hence, this study analyses the potentials in adopting Marine Spatial Planning (MSP) in the TMP for managing the conflict between user and the ecosystem. The Australian Great Barrier Reef Marine Park which applied the zoning of marine area is used as a benchmark to examine the best practices of MSP to govern the TMP. At present, we suggest using coral reef health status as an early alternative and best practice to provide different zoning criteria for strategic marine protected area (MPA) management for TMP.

The extent and protection of Australia’s deep sea

Context Australia has the third largest exclusive economic zone in the world, but little is known about its deepest parts because, historically, research has focussed on coast regions or in the top 1000 m. Aim We aim to identify the extent of Australia’s deep sea, the deepest locations in Australian waters, and investigate how much of Australia’s deep sea is located within marine parks. Methods We use altimetry-derived water depth to calculate the total area in 1000-m bins. Key results The total area of Australian waters, excluding Antarctic waters, is 8 914 134 km2, of which, 70.4% is deep sea greater than 1000 m and 48% is deeper than the 3000-m abyssal boundary. In total, 56% of Australian Marine Parks are deeper than 3000 m and 20 of 61 marine reserves include water deeper than 5000 m. Conclusions The Convention on Biological Diversity calls for marine protected areas globally to increase from 7.7 to 30% by 2030: Australia has already placed over 40% of its waters under protection. Despite this, there are no long-term programs monitoring the deep sea and Australia has not produced a globally significant amount of deep-sea science. Implications Herein lies opportunities for Australia to understand fully its largest habitat and become the global exemplar of deep-sea science and conservation.

Combining spatial ecology and economics to incorporate recreational fishing into marine spatial planning

Abstract Many researchers have pointed to coastal environments and their use for energy production, aquaculture, and conservation as key to solving profound challenges facing humanity. Navigating this transition in ocean space necessitates tools to quantify impacts on displaced marine users, including recreational fishers. In this study, we present a novel method combining spatial ecological models of recreational catch with fine-scale random utility models of site choice to predict the impacts of site closures on recreational fishing experiences (fisher welfare). We demonstrate our approach by modelling data from over 10 000 fishing trips to fine-scale sites across 1500 km of coastline in the south-west of Australia and simulating the effects of no-take marine reserves recently implemented in the Australian Marine Parks. The results show how the combination of random utility modelling with spatial ecological methods provides a powerful tool for investigating recreational fisheries as joint social-ecological systems and incorporating recreational fishing into marine spatial planning.

Coral Communities on Marginal High-Latitude Reefs in West Australian Marine Parks

Many temperate reefs are experiencing a shift towards a greater abundance of tropical species in response to marine heatwaves and long-term ocean warming worldwide. Baseline data for coral communities growing in high-latitude reefs is required to better understand ecosystem changes over time. In this study, we explore spatial and temporal trends in the distribution of coral communities from 1999 to 2019 at 118 reef sites within the five marine parks located in the south-west of Western Australia (WA) between 30° to 35° S. Our estimates of coral cover were generally low (<5%), except for a few sites in Jurien Bay Marine Park and Rottnest Island Marine Reserve where coral cover was 10% to 30%. Interannual changes in genera assemblages were detected but were not consistent over time, whereas significant temporal increases in coral cover estimates were found at the lowest latitude site in Jurien Bay. Coral assemblages were primarily distinguished by Turbinaria spp. at Marmion Marine Park and Ngari Capes Marine Park, and Pocillopora spp. and Dipsastraea spp. at Rottnest Island and Jurien Bay. Our findings suggest that conditions in south-west WA are favorable to the ongoing survival of existing genera and there were minimal signs of expansion in coral cover at most study sites. Coral cover and composition on these reefs may, however, change with ongoing ocean warming and increased occurrence of marine heatwaves. This study provides a valuable benchmark for assessing future changes in coral assemblages and highlights the need for targeted hard-coral surveys to quantify subtle changes in high-latitude coral community assemblages.

Biological Sound Sources Drive Soundscape Characteristics of Two Australian Marine Parks

Soundscapes represent an intrinsic aspect of a habitat which, particularly in protected areas, should be monitored and managed to mitigate human impacts. Soundscape ecology characterizes acoustic interactions within an environment, integrating biological, anthropogenic, climatological, and geological sound sources. Monitoring soundscapes in marine protected areas is particularly important due to the reliance of many marine species on sound for biological functions, including communication and reproduction. In this study we establish a baseline understanding of underwater soundscapes within two marine National Park Zones (NPZs) along the east coast of Australia: Cod Grounds Marine Park and an NPZ surrounding Pimpernel Rock within Solitary Islands Marine Park. In each of the NPZs, underwater recorders were deployed twice during the austral winter (33–35 days, 2018 and 60–69 days, 2019) and once during the austral summer (35–71 days, 2018–2019). We used the resulting acoustic recordings to determine hourly presence of anthropogenic and biological sounds between 20 Hz and 24 kHz and analyze their contributions to patterns of received sound levels. Sounds from vessels were recorded on most days throughout monitoring but were not found to influence long-term patterns of sound levels over their corresponding frequencies. Biological sources included dolphins, snapping shrimp, fish choruses, humpback whales, and dwarf minke whales. Dolphins, snapping shrimp, and fish choruses were present in all deployments. Median ambient sound levels showed a consistent diel pattern with increased levels resulting from crepuscular fish choruses combined with a higher intensity of snapping shrimp snaps during those times. Singing humpback whales strongly influenced the overall sound levels throughout the winter migration, while dwarf minke whales were consistently detected in the 2019 winter deployment but were only present in 2 h among the earlier deployments. Patterns of acoustic spectra were similar between the two NPZs, and patterns of soundscape measurements were observed to be driven by seasonal differences in biological contributions rather than anthropogenic sound sources, indicating that these NPZs are not yet heavily impacted by anthropogenic noise. These baseline measurements will prove invaluable in long-term monitoring of the biological health of NPZs.

A roadmap for integrating eDNA in Australian marine park monitoring

Australia has one of the world’s largest marine park estates. At 3.3 million km2, it spans an area three times larger than Germany, France, and the UK combined. Managing and monitoring such a vast and often remote area is logistically challenging and expensive. Current monitoring of Australian parks is decentralised and depends on traditional survey methods. As a result, real-time data on the state of Australia’s marine parks is incomplete, hampering effective management. Environmental DNA has been suggested as a potential solution to some of these challenges, but practical large-scale applications remain largely lacking in Australia. To overcome this, we are developing a roadmap towards integrating eDNA methods in marine park monitoring. We present an overview of the current state of marine monitoring in Australia marine, identify the aspects of bio-monitoring that eDNA can best contribute to, and suggest pathways towards best practice use of eDNA for resource managers in Australia and globally.

Establishing the ecological basis for conservation of shallow marine life using Reef Life Survey

Reef Life Survey (RLS) provides a new model for ecological monitoring through training experienced recreational divers in underwater visual census methods to the level of skilled scientists. Detail produced is similar to that of programs with professional scientific teams, at low cost to allow global coverage. RLS differs from most other citizen science initiatives in its emphasis on rigorous training and data quality rather than open participation, selectively involving the most skilled and committed members. Volunteers participate primarily because they appreciate the close relationship with scientists, other divers, and managers, and see their efforts directly contributing to improved environmental outcomes. RLS works closely with Australian management agencies, scheduling annual events at core monitoring sites associated with 10 inshore marine protected areas Australia-wide. Surveys of 12 offshore Australian Marine Parks (AMPs) are realized through 2–4 week voyages in a sailing catamaran crewed by volunteers. Across the AMP network, RLS surveys have quantified densities of fishes, mobile invertebrates, macroalgae and corals at 350 shallow coral reef sites (180 sites surveyed on two or more occasions), providing an understanding of (i) population changes amongst threatened species including sea snakes, (ii) responses of fish and invertebrate populations following fisheries closures, (iii) ecosystem-wide impacts of marine heat-waves, and (iv) the extent that AMPs spanning the network comprehensively encompass national coral reef biodiversity. This scientist/volunteer/manager collaboration could be greatly expanded globally (presently 3537 sites in 53 countries).

Sleuthing with sound: Understanding vessel activity in marine protected areas using passive acoustic monitoring

Monitoring compliance and enforcing laws are integral to ensuring the success of marine protected areas (MPAs), but traditional monitoring techniques are costly and resource demanding. Three SoundTrap 300 recorders were deployed for one month between 1 July and September 12, 2018 to collect acoustic data in two marine parks off southeastern Australia: one recorder in Cod Grounds Marine Park (CGMP) and two in the Solitary Islands Marine Park National Park Zone (SIMP NPZ). Extractive activities such as fishing are not permitted in these zones. Raven Pro 2.0 was used to analyze data for vessel presence. Transmission loss equations for each site were generated using patrol boat GPS tracks and used to predict if acoustically recorded vessels were inside park boundaries based on received sound levels. In CGMP, 41 vessels were predicted within the park during the recording period; 34 vessels were predicted within the SIMP NPZ. Thursdays and Saturdays were identified as peak days for vessel presence in CGMP while Thursdays were the peak day in the SIMP NPZ. Most vessel activity at both locations took place between 06:00 and 17:00 AEST. Peak vessel presence in CGMP occurred at 09:00 AEST while the peak vessel presence in the SIMP NPZ occurred at 16:00 AEST. Approximately 12.7 h of vessel sounds were recorded within CGMP; approximately 3.8 h of vessel noise were recorded within the SIMP NPZ. Passive acoustic monitoring of vessel patterns in Australian Marine Parks has provided valuable insight to redirect compliance decisions on how to focus surveillance efforts.

Submerged Carbonate Banks Aggregate Pelagic Megafauna in Offshore Tropical Australia

The conservation of marine biodiversity is firmly embedded in national and international policy frameworks. However, the difficulties associated with conducting broad-scale surveys of oceanic environments restrict the evidence base available for applied management in pelagic waters. For example, the Oceanic Shoals Australian Marine Park (AMP) was established in 2012 in a part of Australia’s continental shelf where unique topographic features are thought to support significant levels of biodiversity, yet where our understanding of ecological processes remains limited. We deployed midwater baited remote underwater video systems (midwater BRUVs) in the Oceanic Shoals AMP to provide the first non-extractive baseline assessment of pelagic wildlife communities in the area. We used these observations and high-resolution multibeam swaths of the seafloor to explore potential relationships between prominent geomorphological features and the (i) composition, (ii) richness, and (iii) total abundance of pelagic communities. We documented 32 vertebrate species across three sampling areas, ranging from small baitfish to large sharks and rays, and estimated that up to twice as many taxa may occur within the region as a whole. This highlights the Oceanic Shoals AMP as a reservoir of biodiversity comparable to other documented offshore oceanic hotspots. Our results also confirm the AMP as a possible distant foraging destination for IUCN red listed sea turtles, and a potential breeding and/or nursing ground for a number of charismatic cetaceans. Model outputs indicate that both species richness and abundance increase in proximity to raised geomorphic structures such as submerged banks and pinnacles, highlighting the influence of submarine topography on megafauna distribution. By providing a foundational understanding of spatial patterns in pelagic wildlife communities throughout a little studied region, our work demonstrates how a combination of non-destructive sampling techniques and predictive models can provide new opportunities to support decision-making under data shortage.

Evaluating South Australian Marine Parks: is climate change adaptation covered?

Evaluating South Australian Marine Parks: is climate change adaptation covered?

Fish-habitat associations on a subsea pipeline within an Australian Marine Park

Subsea pipelines have been installed in all major hydrocarbon basins across the globe to support the offshore Oil & Gas (O&G) industry. These artificial structures provide hard substratum that can be colonised and utilised by sessile and mobile organisms. The present study utilises industry-collected remotely operated vehicle (ROV) video to assess fish species richness and abundance, and marine growth type, extent and complexity along sections of a subsea gas pipeline, in 56–82 m depth, that traverses the Australian Commonwealth Montebello Marine Park (MMP). A total of 7493 fish from 81 species and 33 families were recorded from 606 analysed 10 m transects spaced across sections of the pipeline. Of these 81 species, 27 are considered fishery-target species in the Pilbara Demersal Scalefish fishery (PDSF), with select commercial fishing activities permitted with authorisation within the Marine Park. A moderate abundance (175) of sub-adult red emperor (Lutjanus sebae), a fishery-indicator species, were observed along the pipeline. Eleven different categories of marine growth habitat were observed, with the pipeline possessing quite uniform coverage of encrusting marine growth (coralline algae, bryozoans, ascidians, etc.) with patchy occurrences of more structurally complex sponges and black/octocoral forms. Fish species richness and abundance of the commercially targeted Moses’ snapper (Lutjanus russellii) were correlated positively with increasing cover of sponges. The pipeline itself had very few spans and was never more than fractionally buried. Despite the somewhat homogenous habitats, depths, and position of the pipeline relative to the seafloor, presence of a field joint indent had a positive influence on the abundance of some common and commercially important fish species. This study demonstrates the ecological value of ROV footage obtained during industry inspection operations that were conducted for reasons unrelated to the determination of ecological information. The pipeline offers a corridor of hard bottom habitat within a marine park that facilitates epibiotic growth and the presence of reef-associated species in a region characterised by sandy sediments. Results indicate the potential importance of subsea O&G infrastructure as a habitat for fish, and in consequence, potentially also as structures with value to fisheries.

A cross continental scale comparison of Australian offshore recreational fisheries research and its applications to Marine Park and fisheries management

Abstract Recreational fishing is popular in Australia and is managed by individual states in consultation with the Commonwealth for those fisheries that they regulate and also for Australian Marine Parks (AMPs). Fishers regularly access both state and offshore Commonwealth waters but this offshore component of the recreational fishery is poorly understood. Our study tested the functionality of existing state-based surveys in Western Australia (WA) and New South Wales (NSW) to better inform Commonwealth fisheries and AMP managers about recreational fishing in their jurisdictions. Catch estimates for nine species of interest to the Commonwealth were developed and two case study AMPs [Ningaloo (WA) and The Hunter (NSW)] were also chosen to test the ability of the state survey data to be disaggregated to the park scale. As each state’s fishery survey designs were contextual to their own management needs, the application of the data to Commonwealth jurisdictions were limited by their statistical power, however aspects of each states surveys still provided useful information. Continued evolution of state-wide survey methods, including collection of precise spatial data, and regional over-sampling would be beneficial, particularly where there are multiple stakeholder and jurisdictional interests. National coordination, to temporally align state surveys, would also add value to the existing approaches.

Preventing noncompliance in marine protected areas using a real-time alert system

Effective compliance is a key element to the successful management of marine protected areas (MPAs), and requires a suite of tools to generate awareness of MPA rules, and monitor and regulate their use. Using vessel monitoring systems and creating geo-fences around MPA boundaries is an innovative approach to improve such awareness to vessel masters and commercial fishing licence holders with these systems on-board. In 2014, Parks Australia in partnership with the Australian Fisheries Management Authority (AFMA) introduced a purpose-built alert service for commercial fishing licence holders operating in Australian Commonwealth fisheries managed by AFMA that overlap with MPAs (Australian marine parks). The alert service is customised for each individual fishing vessel to notify masters and licence holders when they enter Australian marine parks where their particular fishing method is prohibited. Since the introduction of the alert service in 25 marine parks, fishers have received 3307 alerts, across eight fisheries. It is estimated that 23 of these alerts averted compliance incidents, in turn protecting marine park values and saving AUD$4.7 million in litigation costs. Of significance, there has been no recorded incidence of noncompliance by Australian commercial fishing licence holders and their vessel master's with access to the alert service since its introduction. The information presented here is the first empirical analysis of the effectiveness of geo-fencing to minimise noncompliance in MPAs. The alert service has the potential to become a front-line tool for supporting compliance by commercial fishing licence holders and their master's in Australian marine parks and other large-scale MPAs and MPA networks, globally.

Demonstrating an acceptable level of impact: an assessment of noise impacts to fishes from a seismic survey in an Australian Marine Park

A key challenge of the environmental regulatory framework for offshore petroleum activities in Australia is the requirement to demonstrate acceptability, with the legislation placing the onus on petroleum titleholders to demonstrate that the impacts and risks posed by an activity will be of an acceptable level and reduced to as low as reasonably practicable. This paper presents a case study on the assessment of noise impacts to fishes for the Bethany 3D Marine Seismic Survey, which was acquired by Santos Ltd in mid-2018. The survey area was encompassed entirely by the Oceanic Shoals Marine Park, and also overlapped a significant proportion of the Timor Reef Fishery, a regionally important demersal scalefish fishery. The survey area overlapped a key ecological feature and a range of geomorphic features characterised by benthic habitats supporting demersal and benthic fish communities, including site-attached species. On this basis, the evaluation of impacts and risks required a multi-faceted approach, with seven key elements: (1) acoustic modelling; (2) application of sound exposure guidelines; (3) a quantitative risk assessment (benthic habitat predictive modelling and spatial analysis of site-attached fish assemblages); (4) the definition of an acceptable level of impact; (5) a sound source verification process; (6) engagement with key stakeholders; and (7) an independent, expert peer review process. The outcomes of each of these steps were incorporated into the environment plan, and enabled the titleholder to demonstrate that, with adopted control measures in place, environmental impacts and risks from the seismic survey could be managed to an acceptable level.

Polychaetes (Annelida) of the Oceanic Shoals region, northern Australia: considering small macrofauna in marine management

Northern Australia has been the focus of recent marine biodiversity research to support natural resource management for both industry and conservation, including management of the Oceanic Shoals Australian Marine Park (AMP). Much of this research has targeted habitat-forming sessile invertebrates and charismatic megafauna, but smaller macrofauna and infauna may also be important because of their roles in ecosystem functions. In this study we characterised the biodiversity of polychaetes collected from four marine surveys to the Oceanic Shoals AMP between 2009 and 2012 from which sediment samples were elutriated (500μm) to separate macrofauna. We used this species-level inventory to examine several questions related to marine management, namely: (1) do polychaete assemblages vary among surveys; (2) can environmental variables or geomorphology explain differences in community structure; and (3) how do ecological patterns change according to taxonomic resolution (species, family) and functional group (feeding, habitat, mobility)? A total of 2561 individual polychaetes were collected from 266 samples, representing 368 species and 43 families, including new species and genera, as well as new family records for Australia (Iospilidae, Lacydoniidae). Polychaete species assemblages and functional groups showed variation among the surveys, but this was not observed at the family level. Species and family assemblages were weakly related to environmental factors, but functional groups showed stronger relationships. Plains and banks each supported distinct polychaete assemblages, although the latter showed temporal variation. The results provide baseline biodiversity and ecological data about polychaetes on the northern Australian shelf, and these are discussed in relation to marine management strategies. Notably, intersurvey and environmental patterns differ from those of larger sessile fauna (sponges) collected on the same surveys, highlighting the need to consider small macrofauna in monitoring programs of marine protected areas.