Dominic McAfee

Multi‐species restoration accelerates recovery of extinguished oyster reefs

Publisher: Wiley

Date: 09-08-2020

DOI: 10.1111/1365-2664.13719

Abstract: A multi‐species approach to habitat restoration may boost the key processes (e.g. recruitment) that enable foundation species to overcome barriers to recovery. Natural systems tend to be formed by co‐occurring foundation species whose synergy drives ecological productivity and resilience beyond that of single foundation species. Yet, restoration remains primarily a single‐species focus enterprise where positive interactions are seldom incorporated into planning. A multi‐species approach that prioritizes species combinations that create emergent properties for their persistence may accelerate habitat recovery and the success of restoration programmes. On the largest oyster reef restoration project in the Southern Hemisphere, we experimentally established canopy‐forming kelp to test whether they could accelerate the natural recruitment of oysters to substrata monopolized by turf‐forming algae. To understand whether facilitation of oysters was a function of the kelp themselves (biological facilitation) or the physical environment they create (physical facilitation), we compared recruitment to the understorey of living kelp and synthetic kelp mimics. Despite observing high density oyster recruitment to the turf‐free underside of reef boulders (8,300 oysters/m 2 ), turf algae appeared to inhibit oyster recruitment to the exposed surfaces of the reef, limiting their capacity to grow and form complex, three‐dimensional habitat. Transplanted kelp, whether living or synthetic kelp mimics, effectively reduced the biomass of turf and enhanced oyster recruitment, creating turf‐free substrata on the upper reef surfaces with up to 26 times the oyster recruitment than turf‐covered substrata. Synthesis and applications . Our results provide proof‐of‐concept that incorporating the transplant of canopy‐forming kelp to reefs constructed to restore oysters is not only achievable, but may be imperative to successfully restore oyster reefs in turf‐dominated systems. Kelp transplants suppressed the turf algae that otherwise excluded oysters from the reef surface, effectively shifting the competitive advantage toward oyster recovery by maintaining bare substrata for oyster recruitment. By demonstrating that a multi‐species approach to restoration accelerates the recovery of a restored habitat, we emphasize the value of incorporating the multi‐species concept into restoration planning.

A Clear-Sighted Focus On Climate- Friendly Operations Will Enhance Sustainable Marine Aquaculture Approaches

Publisher: Oxford University Press (OUP)

Date: 26-08-2022

DOI: 10.1093/BIOSCI/BIAC067

Balancing the Benefits of Optimism and Pessimism in Conservation: a Response to Kidd, Bekessy, and Garrard

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.TREE.2019.05.004

Multi-habitat seascape restoration: optimising marine restoration for coastal repair and social benefit

Publisher: Frontiers Media SA

Date: 04-08-2012

DOI: 10.3389/FMARS.2022.910467

Abstract: Marine ecosystem restoration is fast becoming the primary tool for repairing the socio-ecological functions and economic benefits of coastal ecosystems. Healthy seascapes are characterized by many interacting species and intermingled habitats (e.g., seagrass, kelp, shellfish, sedimentary) that co-create ecological functions of substantial socio-economic value. These co-created functions not only build stability and resilience at seascape scales, but synergistically combine to enhance ecological productivity that is greater than the sum of the in idual habitats. Yet, restoration practice is dominated by single-habitat approaches underpinned by single-species monocultures, potentially limiting the range of benefits that restoration can provide. We propose that for ecosystem restoration to meet its full potential in delivering socio-ecological benefits that are resilient to environmental change, restoration practices should plan beyond single-species and single-habitats to a multi-habitat seascape. Where multiple habitats are co-restored, their positive interactions mutually benefit each other to stabilize and even accelerate ecosystem recovery such as co-restored shellfish and kelp forests on constructed reefs, which combine to stabilize sediment for seagrass recovery. As fisheries scientists and managers, food and social scientists, and ecologists and oceanographers, we describe multi-habitat marine restoration activities that are readily achievable and provide a vision for the erse socio-ecological, economic, and culture benefits that may emerge from future seascape-level repair.

Intraspecific differences in the transcriptional stress response of two populations of Sydney rock oyster increase with rising temperatures

Publisher: Inter-Research Science Center

Date: 23-02-2018

DOI: 10.3354/MEPS12455

Structural traits dictate abiotic stress amelioration by intertidal oysters

Publisher: Wiley

Date: 28-09-2018

DOI: 10.1111/1365-2435.13210

The value and opportunity of restoring Australia's lost rock oyster reefs

Publisher: Wiley

Date: 21-02-2020

DOI: 10.1111/REC.13125

The global fall and rise of oyster reefs

Publisher: Wiley

Date: 07-12-2020

DOI: 10.1002/FEE.2291

Soundscape enrichment enhances recruitment and habitat building on new oyster reef restorations

Publisher: Wiley

Date: 25-10-2022

DOI: 10.1111/1365-2664.14307

Abstract: Marine soundscapes provide important navigational cues to dispersing larvae in search of suitable habitat. Yet, widespread habitat loss has degraded marine soundscapes and their functional role in recruitment. Habitat restoration efforts can provide suitable substrate for habitat regeneration, such as constructing reefs to facilitate recruitment and habitat growth by oysters, but typically occur where soundscapes are degraded and recruitment is limited. Enhancing marine soundscapes on newly constructed reefs using speaker technology may ensure sufficient recruitment to establish a trajectory of recovery for the desired habitat. Across two of the largest oyster reef restorations in Australia, we deployed low‐cost marine speakers at four sites and at three times throughout the recruitment season to test whether soundscape enrichment could boost recruitment and habitat formation by oysters. In the presence and absence of soundscape playback, we compared oyster recruitment rates to settlement panels across space and time, and oyster habitat cover and three‐dimensional habitat building on newly constructed boulder reefs. On the settlement panels deployed across the two reef restorations, soundscape playback significantly increased oyster recruitment at 8 of the 10 sites by an average (±1 SE) 5.1 ± 1.9 times (5281 ± 1384 more larvae per m 2 ), and by as much as 18 times. On boulders atop newly constructed reefs, where the restoration goal is for oysters to form three‐dimensional habitat, the surface area covered by oysters after 5 months did not differ between speaker and control treatments. However, soundscape playback appeared to influence the earlier recruitment of oysters, resulting in significantly more large oysters per boulder that formed significantly more three‐dimensional habitat building by an average 4.3 ± 1.2 times relative to nonspeaker controls. Synthesis and applications . Our results show that using speakers to enrich marine soundscapes at new restoration sites can boost oyster recruitment, resulting in more larger oysters that form more three‐dimensional habitat atop reef restorations. In accelerating the formation of these vertical growth forms, which provide the ecological functions that motivate restoration efforts, the early application of speaker technology on new reef restorations may help steer ecological succession on a trajectory of desired habitat recovery, potentially reducing the substantial cost of ongoing intervention.

Turning a lost reef ecosystem into a national restoration program

Publisher: Wiley

Date: 07-08-2022

DOI: 10.1111/COBI.13958

Abstract: Achieving a sustainable socioecological future now requires large‐scale environmental repair across legislative borders. Yet, enabling large‐scale conservation is complicated by policy‐making processes that are disconnected from socioeconomic interests, multiple sources of knowledge, and differing applications of policy. We considered how a multidisciplinary approach to marine habitat restoration generated the scientific evidence base, community support, and funding needed to begin the restoration of a forgotten, functionally extinct shellfish reef ecosystem. The key actors came together as a multidisciplinary community of researchers, conservation practitioners, recreational fisher communities, and government bodies that collaborated across sectors to rediscover Australia's lost shellfish reefs and communicate the value of its restoration. Actions undertaken to build a case for large‐scale marine restoration included synthesizing current knowledge on Australian shellfish reefs and their historical decline, using this history to tell a compelling story to spark public and political interest, integrating restoration into government policy, and rallying local support through community engagement. Clearly articulating the social, economic, and environmental business case for restoration led to state and national funding for reef restoration to meet erse sustainability goals (e.g., enhanced bio ersity and fisheries productivity) and socioeconomic goals (e.g., job creation and recreational opportunities). A key lesson learned was the importance of aligning project goals with public and industry interests so that projects could address multiple political obligations. This process culminated in Australia's largest marine restoration initiative and shows that solutions for large‐scale ecosystem repair can rapidly occur when socially valued science acts on political opportunities.

The mechanisms by which oysters facilitate invertebrates vary across environmental gradients

Publisher: Springer Science and Business Media LLC

Date: 02-03-2019

DOI: 10.1007/S00442-019-04359-3

Abstract: The effective use of ecosystem engineers to conserve bio ersity requires an understanding of the types of resources an engineer modifies, and how these modifications vary with biotic and abiotic context. In the intertidal zone, oysters engineer ecological communities by reducing temperature and desiccation stress, enhancing the availability of hard substrate for attachment, and by ameliorating biological interactions such as competition and predation. Using a field experiment manipulating shading, predator access and availability of shell substrate at four sites distributed over 900 km of east Australian coastline, we investigated how the relative importance of these mechanisms of facilitation vary spatially. At all sites, and irrespective of environmental conditions, the provision of hard substrate by oysters enhanced the abundance and richness of invertebrates, in particular epibionts (barnacles and oyster spat) and grazing gastropods. Mobile arthropods utilised the habitat provided by disarticulated dead oysters more than live oyster habitat, whereas the abundance of polychaetes and bivalves were much greater in live oysters, suggesting the oyster filter-feeding activity is important for these groups. In warmer estuaries, shading by oysters had a larger effect on bio ersity, whereas in cooler estuaries, the provision of a predation refuge by oysters played a more important role. Such knowledge of how ecosystem engineering effects vary across environmental gradients can help inform management strategies targeting ecosystem resilience via the amelioration of specific environmental stressors, or conservation of specific community assemblages.

Recentering the role of marine restoration science to bolster community stewardship

Publisher: Elsevier BV

Date: 08-2022

DOI: 10.1016/J.ESG.2022.100149

Combining ecology and technology to kick‐start oyster reef restoration

Publisher: Wiley

Date: 03-07-2023

DOI: 10.1111/REC.13975

Abstract: Techniques that enhance the recruitment of foundation species to restoration sites can inform the ecological development of the restored habitat. However, techniques are often considered in isolation, potentially overlooking synergies from combining them. Native oyster reefs have been lost worldwide, resulting in restoration efforts in systems that are often recruitment limited, or where recruiting oysters must spatially compete with opportunistic species. Here, we present a field‐based study that combines ecological knowledge on positive species interactions with novel acoustic technology, both of which are demonstrated to boost oyster recruitment in isolation, to test whether their interaction synergistically enhances the early larval recruitment that drives oyster reef development. At three sites across a 20 ha oyster reef restoration in southern Australia, we used self‐made speakers to broadcast healthy reef soundscapes that attract oysters and combine this with artificial kelp that facilitates oyster recruitment by suppressing competitive species (turfing algae). The combination of acoustic enrichment and artificial kelp increased oyster recruitment to the topside of substrate (326.98% increase), whereas only acoustic enrichment increased recruitment to the underside of substrate (126.95% increase). Our findings suggest that the combination of multiple techniques and their interactive effects might boost the early stages of reef development, providing proof‐of‐concept that these approaches can help oysters to build and bind reefs (i.e. recruit to the topside and underside, respectively). By combining ecology with technology during the first stages of a developing reef restoration, we show the potential value of these novel approaches to kick‐start the recovery of lost oyster reefs.

Cuing oyster recruitment with shell and rock: implications for timing reef restoration

Publisher: Wiley

Date: 04-03-2020

DOI: 10.1111/REC.13134

Environmental solutions sparked by environmental history

Publisher: Wiley

Date: 16-09-2019

DOI: 10.1111/COBI.13403

Abstract: Environmental solutions require a decision‐making process that is ultimately political, in that they involve decisions with uncertain outcomes and stakeholders with conflicting viewpoints. If this process seeks broad alignment between the government and public, then reconciling conflicting viewpoints is a key to the legitimacy of these decisions. We show that ecological baselines can be particularly powerful tools for creating a common understanding for public support (legitimacy) and conformity to new rules or regulations (legality) that enable the solution. They are powerful because they move the discussion of solutions from the abstract to the concrete by providing a conceptual model for a common expectation (e.g., restoring habitat). They provide narratives of the past (ecological histories) that readjust the future expectations of in iduals on how to perceive and respond to new policy. While ecological baselines offer scientists benchmarks for reinstating ecological functions, they also normalize public and government discussion of solutions. This social normalization of public issues may assist government policy and influence social views, practices, and behaviors that adopt the policy. For science to more effectively inform conservation, we encourage interdisciplinary thinking (science‐ and human‐centered) because it can provide public support and government legitimacy for investing in environmental solutions.

Latitudinal gradients in ecosystem engineering by oysters vary across habitats

Publisher: Wiley

Date: 04-2016

DOI: 10.1890/15-0651.1

Abstract: Ecological theory predicts that positive interactions among organisms will increase across gradients of increasing abiotic stress or consumer pressure. This theory has been supported by empirical studies examining the magnitude of ecosystem engineering across environmental gradients and between habitat settings at local scale. Predictions that habitat setting, by modifying both biotic and abiotic factors, will determine large-scale gradients in ecosystem engineering have not been tested, however. A combination of manipulative experiments and field surveys assessed whether along the east Australian coastline: (1) facilitation of invertebrates by the oyster Saccostrea glomerata increased across a latitudinal gradient in temperature and (2) the magnitude of this effect varied between intertidal rocky shores and mangrove forests. It was expected that on rocky shores, where oysters are the primary ecosystem engineer, they would play a greater role in ameliorating latitudinal gradients in temperature than in mangroves, where they are a secondary ecosystem engineer living under the mangrove canopy. On rocky shores, the enhancement of invertebrate abundance in oysters as compared to bare microhabitat decreased with latitude, as the maximum temperatures experienced by intertidal organisms diminished. By contrast, in mangrove forests, where the mangrove canopy resulted in maximum temperatures that were cooler and of greater humidity than on rocky shores, we found no evidence of latitudinal gradients of oyster effects on invertebrate abundance. Contrary to predictions, the magnitude by which oysters enhanced bio ersity was in many instances similar between mangroves and rocky shores. Whether habitat-context modifies patterns of spatial variation in the effects of ecosystem engineers on community structure will depend, in part, on the extent to which the environmental amelioration provided by an ecosystem engineer replicates that of other co-occurring ecosystem engineers.

Temperature-buffering by oyster habitat provides temporal stability for rocky shore communities

Publisher: Elsevier BV

Date: 2022

DOI: 10.1016/J.MARENVRES.2021.105536

Abstract: Intertidal rocky shores are considered among the most thermally stressful marine ecosystems, where many species live close to their upper thermal limit and depend on access to cool microclimates to persist through heat events. In such environments, the provision of cool microclimates by habitat-forming species enables persistence of associated species during high temperature events. We assessed whether, by maintaining cool microclimates through heat events, habitat formed by rock oysters (Saccostrea cucullata) provides temporal stability to associated invertebrate communities over periods of extreme temperatures. On three tropical rocky shores of Hong Kong, which experiences a monsoonal climate, we compared changes in microclimates and invertebrate communities associated with oyster and bare rock habitats between the cool and hot seasons. Oyster habitats were, across both seasons, consistently characterised by lower maximum temperatures and greater thermal stability than bare rock habitats. Invertebrate communities in the bare rock habitat were less erse and abundant in the hot than the cool season, but communities in the cooler habitats provided by oysters did not display temporal change. These results demonstrate that microclimates formed by oysters provide temporal stability to associated communities across periods of temperature change and are key determinants of species distributions in thermally stressful environments. The conservation and restoration of oyster habitats may, therefore, build resilience in associated ecological communities subject to ongoing environmental change.

Oyster larvae swim along gradients of sound

Publisher: Wiley

Date: 10-05-2022

DOI: 10.1111/1365-2664.14188

Abstract: Marine soundscapes provide navigational information for dispersing organisms, but with wide‐scale habitat loss, these soundscapes are becoming muted. Consequently, dispersing larvae that use soundscapes for navigation may be lost at sea, limiting the success of restoration efforts that rely upon the recruitment of dispersing organisms to restore habitat. Where limited larval supply constrains restoration efforts, using speakers to create gradients in healthy soundscapes could provide the navigational cue that attract larvae and enhances recruitment. Combining laboratory and field studies, we test whether broadcasting soundscapes might act as a directional cue for oysters targeted for national‐scale reef restoration the Australian flat oyster Ostrea angasi . In the laboratory, we tested whether settlement of larvae increases along a gradient of increasing sound intensity (8 m laboratory tank) versus a no sound control, and whether settlement increases with soundscapes that approximate healthy reefs. In the field, we tested the context dependency and magnitude of using boosted soundscapes for restoration practice in areas of low, medium and high background noise, by observing the settlement rates of naturally recruiting oysters at three restoration sites when exposed to boosted reef sound relative to ambient conditions. In the laboratory, we showed that 83% of larvae swim horizontally towards reef sound to settle in greater densities closer to its source, a near doubling of the larvae (44%) that dispersed in the no sound controls. Larval settlement increased by 300% in the presence of reef sound relative to controls in the laboratory. In the field, speakers increased larval settlement in localities of lower background noise. To our knowledge, this is the first evidence that oyster larvae can swim horizontally and choose to move towards a sound source. Synthesis and applications . We discovered that oyster larvae can swim horizontally towards reef sound and then settle in higher densities, relative to controls. Importantly, this effect of sound on recruitment is enhanced in localities of lower background noise. We propose that where recruitment is limited, restoration practitioners best use acoustic technology in localities of lower background noise to guide larvae to boost recovery.

Stress across life stages: Impacts, responses and consequences for marine organisms

Publisher: Elsevier BV

Date: 2020

DOI: 10.1016/J.SCITOTENV.2019.134491

Abstract: Population dynamics of marine organisms are strongly driven by their survival in early life stages. As life stages are tightly linked, environmental stress experienced by organisms in the early life stage can worsen their performance in the subsequent life stage (i.e. carry-over effect). However, stressful events can be ephemeral and hence organisms may be able to counter the harmful effects of transient stress. Here, we analysed the published data to examine the relative strength of carry-over effects on the juvenile growth of marine organisms, caused by different stressors (hypoxia, salinity, starvation, ocean acidification and stress-induced delayed metamorphosis) confronted in their larval stage. Based on 31 relevant published studies, we revealed that food limitation had the greatest negative carry-over effect on juvenile growth. In the laboratory, we tested the effects of short-term early starvation and hypoxia on the larval growth and development of a model organism, polychaete Hydroides elegans, and assessed whether the larvae can accommodate the early stress to maintain their performance as juveniles (settlement and juvenile growth). Results showed that early starvation for 3 days (∼50% of normal larval period) retarded larval growth and development, leading to subsequent reduced settlement rate and juvenile growth. When the starvation period decreased to 1 day, however, the larvae could recover from early starvation through compensatory growth and performed normal as juveniles (c.f. control). Early exposure to hypoxia for 3 days did not affect larval growth (body length) and juvenile growth (tube length), but caused malformation of larvae and reduced settlement rate. We conclude that the adverse effects of transient stress can be carried across life stages (e.g. larval to juvenile stage), but depend on the duration of stressful events relative to larval period. As carry-over effects are primarily driven by energy acquisition, how food availability varies over time and space is fundamental to the population dynamics of marine organisms.

The COVID-19 lockdown provides clues for better science communication on environmental recovery

Publisher: Cambridge University Press (CUP)

Date: 26-10-2021

DOI: 10.1017/S0376892921000369

Repairing recruitment processes with sound technology to accelerate habitat restoration

Publisher: Wiley

Date: 07-07-2021

DOI: 10.1002/EAP.2386

Abstract: Humanity’s ambitions to revive ecosystems at large scales require solutions to move restoration efforts beyond the small scale. There are increasing calls for technological solutions to reduce costs and facilitate large‐scale restoration through the use of emerging technologies using an adaptive process of research and development. We show how technological enrichment of marine soundscapes may provide a solution that repairs the recruitment process to accelerate the recovery of lost marine habitats. This solution would solve the problems of current practice that largely relies upon natural recruitment processes, which carries considerable risk where recruitment is variable or eroded. By combining the literature with laboratory experiments, we describe evidence for “highways of sound” that convey navigable information for dispersing life stages in search for adult habitat. We show that these navigational cues tend to be silenced as their habitat is lost, creating negative feedbacks that hinders restoration. We suggest that reprovisioning soundscapes using underwater technology offers the potential to reverse this feedback and entice target organisms to recruit in greater densities. Collective evidence indicates that the application of soundscape theory and technology may unlock the recruitment potential needed to trigger the recruitment of target organisms and the natural soundscapes they create at large scales.

Conservation status of the Oyster Reef Ecosystem of Southern and Eastern Australia

Publisher: Elsevier BV

Date: 06-2020

DOI: 10.1016/J.GECCO.2020.E00988

Environmental solutions fast-tracked: Reversing public scepticism to public engagement

Publisher: Elsevier BV

Date: 2021

DOI: 10.1016/J.BIOCON.2020.108899

Fast-growing oysters show reduced capacity to provide a thermal refuge to intertidal biodiversity at high temperatures

Publisher: Wiley

Date: 12-10-2017

DOI: 10.1111/1365-2656.12757

Abstract: Ecosystem engineers that modify the thermal environment experienced by associated organisms might assist in the climate change adaptation of species. This depends on the ability of ecosystem engineers to persist and continue to ameliorate thermal stress under changing climatic conditions-traits that may display significant intraspecific variation. In the physically stressful intertidal, the complex three-dimensional structure of oysters provides shading and traps moisture during aerial exposure at low tide. We assessed variation in the capacity of a faster- and slower-growing population of the Sydney Rock Oyster, Saccostrea glomerata, to persist, form three-dimensional structure and provide a cool microhabitat to invertebrates under warmer conditions. The two populations of oysters were exposed to a temperature gradient in the field by attaching them to passively warmed white, grey and black stone pavers and their growth, survivorship and colonisation by invertebrates was monitored over a 12-month period. Oysters displayed a trade-off between fast growth and thermal tolerance. The growth advantage of the fast-growing population diminished with increasing substrate temperature, and at higher temperatures, the faster-growing oysters suffered greater mortality, formed less habitat, and were consequently less effective at ameliorating low-tide air temperature extremes than slower-growing oysters. The greater survivorship of slower-growing oysters, in turn, produced a cooler microclimate which fed back to further bolster oyster survivorship. Invertebrate recruitment increased with habitat cover and was greater among the slower than the faster-growing population. Our results show that the capacity of ecosystem engineers to serve as microhabitat refugia to associated organisms in a warming climate displays marked intraspecific variation. Our study also adds to growing evidence that fast growth may come at the expense of thermal tolerance.

University Of Adelaide

Location: Australia

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Macquarie University

Location: Australia

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Linkage Projects - Grant ID: LP200201000

Start Date: 12-2021

End Date: 12-2024

Amount: $355,822.00

Funder: Australian Research Council