As coastal population growth increases globally, effective waste management practices are required to protect biodiversity. Water authorities are under increasing pressure to reduce the impact of ...sewage effluent discharged into the coastal environment and restore disturbed ecosystems. We review the role of benthic macroalgae as ecosystem engineers and focus particularly on the temperate Australasian fucoid Hormosira banksii as a case study for rocky intertidal restoration efforts. Research focussing on the roles of ecosystem engineers is lagging behind restoration research of ecosystem engineers. As such, management decisions are being made without a sound understanding of the ecology of ecosystem engineers. For successful restoration of rocky intertidal shores it is important that we assess the thresholds of engineering traits (discussed herein) and the environmental conditions under which they are important.
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•Fucoid algae can be important ecosystem engineers in rocky reef ecosystems•Sewage-effluent disposal negatively affects fucoids and associated communities•Restoring fucoid populations can improve biodiversity of degraded systems•Clarifying the roles of fucoids in ecosystem function can improve restoration efforts•Thresholds of engineering traits and associated environmental conditions important
The spread of marine pests is occurring at record rates due to globalisation and increasing trade. Environmental DNA (eDNA) is an emerging tool for pest surveillance, allowing for the detection of ...genetic material shed by organisms into the environment. However, factors influencing the spatial and temporal detection limits of eDNA in marine environments are poorly understood. In this study we use eDNA assays to assess the invasive ranges of two marine pests in south-eastern Australia, the kelp Undaria pinnatifida and the seastar Asterias amurensis. We explored the temporal and spatial detection limits of eDNA under different oceanographic conditions by combining estimates of eDNA decay with biophysical modelling. Positive eDNA detections at several new locations indicate the invasive range of both pest species is likely to be wider than currently assumed. Environmental DNA decay rates were similar for both species, with a decay rate constant of 0.035 h−1 for U. pinnatifida, and a decay rate constant of 0.041 h−1 for A. amurensis, resulting in a 57–73% decrease in eDNA concentrations in the first 24 h and decaying beyond the limits of detection after 3–4 days. Biophysical models informed by eDNA decay profiles indicate passive transport of eDNA up to a maximum of 10 to 20 km from its source, with a ~90–95% reduction in eDNA concentration within 1–3 km from the source, depending on local oceanography. These models suggest eDNA signals are likely to be highly localised, even in complex marine environments. This was confirmed with spatially replicated eDNA sampling around an established U. pinnatifida population indicating detection limits of ~750 m from the source. This study highlights the value of eDNA methods for marine pest surveillance and provides a much-needed description of the spatio-temporal detection limits of eDNA under different oceanographic conditions.
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•eDNA surveys, decay trials and biophysical models are used to assess the geographic range of two invasive species.•eDNA surveys indicate the invasive ranges of the two species are much wider than previously reported.•eDNA for both invasive species decayed rapidly in the first 24 h.•Biophysical models show eDNA signals are highly localised, even in complex marine environments.•Marine pest surveillance and monitoring is expected to be greatly assisted by eDNA technologies.
Warming seas, marine heatwaves, and habitat degradation are increasingly widespread phenomena affecting marine biodiversity, yet our understanding of their broader impacts is largely derived from ...collective insights from independent localized studies. Insufficient systematic broadscale monitoring limits our understanding of the true extent of these impacts and our capacity to track these at scales relevant to national policies and international agreements. Using an extensive time series of co-located reef fish community structure and habitat data spanning 12 years and the entire Australian continent, we found that reef fish community responses to changing temperatures and habitats are dynamic and widespread but regionally patchy. Shifts in composition and abundance of the fish community often occurred within 2 years of environmental or habitat change, although the relative importance of these two mechanisms of climate impact tended to differ between tropical and temperate zones. The clearest of these changes on temperate and subtropical reefs were temperature related, with responses measured by the reef fish thermal index indicating reshuffling according to the thermal affinities of species present. On low latitude coral reefs, the community generalization index indicated shifting dominance of habitat generalist fishes through time, concurrent with changing coral cover. Our results emphasize the importance of maintaining local ecological detail when scaling up datasets to inform national policies and global biodiversity targets. Scaled-up ecological monitoring is needed to discriminate among increasingly diverse drivers of large-scale biodiversity change and better connect presently disjointed systems of biodiversity observation, indicator research, and governance.
Intertidal fucoid algae can function as ecosystem engineers across temperate marine regions. In this investigation, we assessed the function of the alga dominating rocky reefs in temperate Australia ...and New Zealand, Hormosira banksii. Invertebrate and algal species assemblages were examined within areas of full H. banksii canopy, areas where it was naturally patchy or absent (within its potential range on the shore) and areas where the intact canopy was experimentally disturbed. Differences in species assemblages were detected between areas with natural variation in H. banksii cover (full, patchy, negligible), with defined species associated with areas of full cover. Differences were also detected between experimentally manipulated and naturally patchy areas of canopy cover. Species assemblages altered in response to canopy manipulations and did not recover even twelve months after initial sampling. Both light intensity and temperature were buffered by full canopies compared to patchy canopies and exposed rock. This study allows us to predict the consequences to the intertidal community due to the loss of canopy cover, which may result from a range of disturbances such as trampling, storm damage, sand burial and prolonged exposure to extreme temperature, and further allow for improved management of this key autogenic ecosystem engineer.
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).
•Global monitoring of reef communities using standardized visual census methods•Divers assess densities of fishes, reptiles, mobile and sessile invertebrates, and macro-algae•Involves collaboration of highly trained volunteer divers, researchers and managers•Data now collected from 3537 sites in 53 countries•Management agencies use data to assess effects of fishing, climate change and pollution
Introduction
To counteract the rapid loss of marine forests globally and meet international commitments of the UN Decade on Ecosystem Restoration and the Convention on Biological Diversity ‘30 by 30’ ...targets, there is an urgent need to enhance our capacity for macroalgal restoration. The Green Gravel Action Group (GGAG) is a global network of 67 members that are working on the restoration of a diverse range of macroalgal forests and it aims to facilitate knowledge exchange to fast-track innovation and implementation of outplanting approaches worldwide.
Methods
Here, we overview 25 projects conducted by members of the group that are focused on testing and developing techniques for macroalgal restoration. Based on these projects, we summarise the major challenges associated with scaling up the area of marine forests restored.
Results
We identify several critical challenges that currently impede more widespread rollout of effective large-scale macroalgal restoration worldwide: 1) funding and capacity limitations, 2) difficulties arising from conditions at restoration sites, 3) technical barriers, and 4) challenges at the restoration-policy interface.
Discussion
Despite these challenges, there has been substantial progress, with an increasing number of efforts, community engagement and momentum towards scaling up activities in recent years. Drawing on the collective expertise of the GGAG, we outline key recommendations for the scaling up of restoration efforts to match the goals of international commitments. These include the establishment of novel pathways to fund macroalgal restoration activities, building skills and capacity, harnessing emerging innovations in mobile hatchery and seeding technologies, and the development of the scientific and governance frameworks necessary to implement and monitor macroalgal restoration projects at scale.
Marine kelp forests cover 1/3 of our world's coastlines, are heralded as a nature-based solution to address socio-environmental issues, connect hundreds of millions of people with the ocean, and ...support a rich web of biodiversity throughout our oceans. But they are increasingly threatened with some areas reporting over 90% declines in kelp forest cover in living memory. Despite their importance and the threats they face, kelp forests are entirely absent from the international conservation dialogue. No international laws, policies, or targets focus on kelp forests and very few countries consider them in their national policy. The Kelp Forest Challenge addresses that gap. Together with 252 kelp experts, professionals, and citizens from 25 countries, the Kelp Forest Challenge was developed as a grassroots vision of what the world can achieve for kelp forest conservation. It is a global call to restore 1 million and protect 3 million hectares of kelp forests by 2040. This is a monumental challenge, that will require coordination across multiple levels of society and the mobilization of immense resources. Pledges may therefore include area for protection or restoration, enabling pledges which assist in conservation (funding, equipment, professional expertise, capacity building), or awareness-based pledges which increase awareness or education about kelp forests. Correspondingly, participants may be from government, scientific institutions, private sector, NGOs, community groups, or individuals. This challenge is the beginning of a 17-year mission to save our kelp forests and anyone and any organisation is invited to participate.
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