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The global loss of coastal habitats is putting communities at risk of erosion and flooding, as well as impacting ecosystem function, cultural values, biodiversity, and other services. Coastal habitat restoration can provide a nature-based solution to the increasing need for climate adaptation on the coast while recovering lost ecosystems. Despite the benefits of using nature-based coastal protection to manage coastal hazards, there are scientific, sociopolitical and economic barriers to the broad use of this approach. Understanding the details of these barriers from the perspective of multiple stakeholders is essential to identifying solutions to overcome them. Using a workshop with participants that are key partners and stakeholders (from government, engineering consulting firms, and non-governmental organisations) in the management, design, and delivery of a coastal protection solution we aimed to: (1) gain a better understanding of the barriers faced by multiple stakeholders involved in the implementation of nature-based coastal protection; and (2) identify tangible solutions to these barriers to increase or support implementation, help focus attention on areas for future research, and inform pathways forward for the governance of nature-based coastal protection. We defined 19 barriers to nature-based coastal protection, but the primary ones that are experienced during the delivery of a project are a lack of: education and awareness; community support; necessary expertise and technical guidance; and uncertainty around: the risk reduction that can be achieved; planning and regulatory processes; and ownership of the structure. Two barriers that do not persist during the design stages of a project but are overarching as to whether nature-based coastal protection is considered in the first place, are government support and the availability of funding. The importance of these primary barriers changes depending on the method of nature-based coastal protection. We conclude by identifying both immediate actions and long-term solutions for enabling nature-based coastal protection in response to each of the primary barriers. [ABSTRACT FROM AUTHOR]

Lunar rhythms shape spawning phenology and subsequent risks and rewards for early life-history stages in the sea. Here, we consider a perplexing spawning phenology of the sixbar wrasse (Thalassoma hardwicke), in which parents spawn disproportionately around the new moon, despite the low survival of these larvae. Because primary sex determination in this system is highly plastic and sensitive to social environments experienced early in development, we ask whether this puzzling pattern of spawning is explained by fitness trade-offs associated with primary sexual maturation. We used otoliths from 871 fish to explore how spawning on different phases of the moon shapes the environments and phenotypes of settling larvae. Offspring that were born at the new moon were more likely to settle (i) before other larvae, (ii) at a larger body size, (iii) at an older age, (iv) to the best quality sites, and (v) as part of a social group—all increasing the likelihood of primary maturation to male. Selection of birthdates across life stage transitions suggests that the perplexing spawning phenology of adults may reflect an evolutionarily stable strategy that includes new moon spawning for compensatory benefits later in life, including preferential production of primary males at certain times. [ABSTRACT FROM AUTHOR]

Understanding the drivers of ecosystem stability has been a key focus of modern ecology as the impacts of the Anthropocene become more prevalent and extreme. Marine protected areas (MPAs) are tools used globally to promote biodiversity and mediate anthropogenic impacts. However, assessing the stability of natural ecosystems and responses to management actions is inherently challenging due to the complex dynamics of communities with many interdependent taxa. Using a 12‐year time series of subtidal community structure in an MPA network in the Channel Islands (United States), we estimated species interaction strength (competition and predation), prey species synchrony, and temporal stability in trophic networks, as well as temporal variation in sea surface temperature to explore the causal drivers of temporal stability at community and metacommunity scales. At the community scale, only trophic networks in MPAs at Santa Rosa Island showed greater temporal stability than reference sites, likely driven by reduced prey synchrony. Across islands, competition was sometimes greater and predation always greater in MPAs compared with reference sites. Increases in interaction strength resulted in lower temporal stability of trophic networks. Although MPAs reduced prey synchrony at the metacommunity scale, reductions were insufficient to stabilize trophic networks. In contrast, temporal variation in sea surface temperature had strong positive direct effects on stability at the regional scale and indirect effects at the local scale through reductions in species interaction strength. Although MPAs can be effective management strategies for protecting certain species or locations, our findings for this MPA network suggest that temperature variation has a stronger influence on metacommunity temporal stability by mediating species interactions and promoting a mosaic of spatiotemporal variation in community structure of trophic networks. By capturing the full spectrum of environmental variation in network planning, MPAs will have the greatest capacity to promote ecosystem stability in response to climate change. [ABSTRACT FROM AUTHOR]

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Oyster reefs have declined globally, impacting ecosystem structure, function, and services. The flat oyster Ostrea angasi was a dominant ecosystem engineer throughout southern Australia, forming extensive reefs now diminished to <1% of historical coverage. Restoration of O. angasi has gained traction over the last decade, exclusively in subtidal habitats. However, O. angasi historically occurred in the intertidal zone, which could broaden restoration opportunities and success. There is little information quantifying factors that influence the performance of O. angasi in intertidal habitats. To test survival of O. angasi under thermal and desiccation stress experienced in intertidal habitats under winter, summer, and heatwave conditions, we emersed individuals from three age classes (1, 4, and 7 months old) at air temperatures of 10, 25, or 40°C in a series of laboratory experiments. Oysters exhibited moderate tolerance to exposure, with survival depending on interactions between emersion duration and temperature, and emersion duration and shell length. Survival broadly increased with shell length, but decreased with temperature and emersion duration. We used model predictions from the laboratory experiments to simulate intertidal survival rates at a potential restoration site in southern Australia. The simulation revealed low survival when low tides coincided with heatwaves. Field validation is needed to understand the effects of repeated tidal cycles and other biotic and abiotic influences. Our findings provide preliminary evidence for extending the restoration range of O. angasi into the low intertidal zone and can be considered when mitigating transport‐related mortality during large‐scale restoration. [ABSTRACT FROM AUTHOR]

Despite the interest in restoring remnant populations of the Olympia oyster, Ostrea lurida Carpenter 1864,† little is known about connectivity among populations. Identifying the sources of settling larvae could broaden our understanding of the degree to which particular populations are reliant on their neighbors for their persistence. Calcified structures such as the otoliths of fish and statoliths of invertebrates are increasingly being exploited as useful "natural tags" that help track individual movements and, when applicable to larvae, could help to pinpoint important source populations. In controlled laboratory culturing experiments, we explored the prospects for using the chemistry of larval shells (prodissoconchs) as natural tags of larval source by examining whether larval shells record shifts in seawater element chemistry, whether larval shells undergo ontogenetic shifts in element uptake, and whether the chemistry of the shell formed during brooding is compromised by subsequent shell thickening during the planktonic phase. Results from a two-way ANOVA examining the effect of seawater element concentration and ontogeny showed that element/ Ca in the shell increased in response to increasing seawater elemental concentrations for Ba, Ce, Pb, and Mn, whereas shell Cu/Ca did not change. Ostrea lurida shell chemistry also showed strong ontogenetic shifts in element/Ca for Mg, Sr, and Cu during the transition from larva to settler. Settler shell Mg/Ca strongly increased compared with planktonic shell, whereas Sr/Ca and Cu/Ca showed the opposite pattern. Further, the chemistry of the shell formed during brooding (at the birth location) did change as a function of environmental conditions experienced during the planktonic phase for the elements Ba and Ce, but that change was limited to regions of the brooded shell just adjacent to the planktonic shell. When the brooded portions of larval shells were sampled closer to the umbo, the brooded shells' chemistry remains intact. The combined results suggest that larval Ostrea lurida shells act as recorders of environmental change and show promise as tools to track larval movements.

One of the least understood and most fundamental processes in marine ecology is dispersal, or transport of larvae. To what extent are local adult population dynamics influenced by the dispersal of larvae from neighboring source populations? Do self-recruiting populations exist? How far do larvae disperse? The sources and destinations of larvae have been unknown for nearly all commercially important species, yet any model of resource management or biodiversity preservation depends on this information. We wish to understand the interdependency of commercially important California coastal populations by identifying the sources of larval recruits. To do this, we will use environmental signatures, consisting of trace metal inclusions in the hard structures of larvae (e.g., fish otoliths) that are laid down over time. Elements from the surrounding seawater become permanently incorporated into the structures, which then act as daily recorders of the environment experienced during the larval phase. Along coastal margins, concentrations of many trace elements are significantly higher than in the open ocean, and differences in trace element concentrations among coastal water masses occur as well. Recently developed high-precision mass spectrometers and laser microprobes allow a sequential analysis of past environments, down to a resolution of a few days.We propose the following interrelated approaches to the problem of reconstructing larval paths:•Validation: How well and how consistently is water chemistry reflected in the trace element composition of hard parts produced by organisms? Can the techniques be extended to other commercially important species?•Documenting the temporal and spatial nature of environmental signatures: constructing an “atlas” of potential source populations.•Tracing larval sources through microchemical analyses of new recruits by matching core signatures of hard parts to the “atlas”, and through a pilot mark-recapture study.•Integrating the results into ongoing students of population genetics and ocean circulation models.