Current extent and future opportunities for living shorelines in Australia.

Living shorelines aim to enhance the resilience of coastlines to hazards while simultaneously delivering co-benefits such as carbon sequestration. Despite the potential ecological and socio-economic benefits of living shorelines over conventional engineered coastal protection structures, application is limited globally. Australia has a long and diverse coastline that provides prime opportunities for living shorelines using beaches and dunes, vegetation, and biogenic reefs, which may be either natural ('soft' approach) or with an engineered structural component ('hybrid' approach). Published scientific studies, however, have indicated limited use of living shorelines for coastal protection in Australia. In response, we combined a national survey and interviews of coastal practitioners and a grey and peer-reviewed literature search to (1) identify barriers to living shoreline implementation; and (2) create a database of living shoreline projects in Australia based on sources other than scientific literature. Projects included were those that had either a primary or secondary goal of protection of coastal assets from erosion and/or flooding. We identified 138 living shoreline projects in Australia through the means sampled starting in 1970; with the number of projects increasing through time particularly since 2000. Over half of the total projects (59 %) were considered to be successful according to their initial stated objective (i.e., reducing hazard risk) and 18 % of projects could not be assessed for their success based on the information available. Seventy percent of projects received formal or informal monitoring. Even in the absence of peer-reviewed support for living shoreline construction in Australia, we discovered local and regional increases in their use. This suggests that coastal practitioners are learning on-the-ground, however more generally it was stated that few examples of living shorelines are being made available, suggesting a barrier in information sharing among agencies at a broader scale. A database of living shoreline projects can increase knowledge among practitioners globally to develop best practice that informs technical guidelines for different approaches and helps focus attention on areas for further research.

Achieving conservation and restoration outcomes through ecologically beneficial aquaculture.

A range of conservation and restoration tools are needed to safeguard the structure and function of aquatic ecosystems. Aquaculture, the culturing of aquatic organisms, often contributes to the numerous stressors that aquatic ecosystems face, yet some aquaculture activities can also deliver ecological benefits. We reviewed the literature on aquaculture activities that may contribute to conservation and restoration outcomes, either by enhancing the persistence or recovery of one or more target species or by moving aquatic ecosystems toward a target state. We identified 12 ecologically beneficial outcomes achievable via aquaculture: species recovery, habitat restoration, habitat rehabilitation, habitat protection, bioremediation, assisted evolution, climate change mitigation, wild harvest replacement, coastal defense, removal of overabundant species, biological control, and ex situ conservation. This list may be expanded as new applications are discovered. Positive intentions do not guarantee positive ecological outcomes, so it is critical that potentially ecologically beneficial aquaculture activities be evaluated via clear and measurable indicators of success to reduce potential abuse by greenwashing. Unanimity on outcomes, indicators, and related terminology will bring the field of aquaculture-environment interactions into line with consensus standards in conservation and restoration ecology. Broad consensus will also aid the development of future certification schemes for ecologically beneficial aquaculture.

Se necesita una gama de herramientas de conservación y restauración para salvaguardar la estructura y función de los ecosistemas acuáticos. La acuacultura (el cultivo de organismos acuáticos) generalmente contribuye a los numerosos estresantes que soportan los ecosistemas acuáticos, aunque algunas actividades de la acuacultura también pueden proporcionar beneficios ecológicos. Revisamos la literatura sobre las actividades de acuacultura que pueden contribuir a los resultados de conservación y restauración, ya sea al incrementar la persistencia o recuperación de una o más especies objetivo o al llevar a los ecosistemas acuáticos hacia un estado objetivo. Identificamos doce resultados con beneficios ecológicos que pueden lograrse con la acuacultura: recuperación de la especie, recuperación del hábitat, restauración del hábitat, rehabilitación del hábitat, protección del hábitat, bioreparación, evolución asistida, mitigación del cambio climático, sustitución de la captura silvestre, defensa costera, eliminación de las especies sobreabundantes, control biológico y conservación ex situ. Esta lista puede expandirse conforme se descubren nuevas aplicaciones. Las intenciones positivas no garantizan resultados ecológicos positivos, así que es importante que se evalúen las actividades de acuacultura con un posible beneficio ecológico por medio de indicadores del éxito claros y medibles para reducir el abuso potencial por ecoblanqueo o greenwashing. La unanimidad en los resultados, indicadores y terminología relacionada armonizará las interacciones entre la acuacultura y el ambiente con los estándares de la conservación y la ecología de la restauración. Un consenso generalizado también ayudará con el desarrollo de futuros esquemas de certificación para la acuacultura con beneficios ecológicos. Obtención de resultados de conservación y restauración a través de la acuacultura con beneficios ecológicos.

Effects of protection and temperature variation on temporal stability in a marine reserve network.

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.

Efectos de la protección y variación de la temperatura sobre la estabilidad temporal en una red de reservas marinas Resumen El conocimiento sobre las causas de la estabilidad ambiental ha sido un enfoque importante de la ecología moderna conforme el impacto del Antropoceno se vuelve más prevaleciente y extremo. Las áreas marinas protegidas (AMP) son herramientas que se usan en todo el mundo para promover la biodiversidad y mediar el impacto antropogénico. Sin embargo, analizar la estabilidad de los ecosistemas naturales y la respuesta a las acciones de manejo es complicado debido a las dinámicas complejas entre las comunidades y varios taxones interdependientes. Usamos una serie temporal de 12 años de estructura comunitaria submareal en una red de AMP en las Islas del Canal (Estados Unidos) para estimar la fuerza de interacción de las especies (competencia y depredación), la sincronía de las especies depredadas y la estabilidad temporal en las redes tróficas, así como la variación temporal de la temperatura superficial del mar para explorar los factores causales de la estabilidad temporal a escala comunitaria y meta-comunitaria. A nivel de comunidad, sólo las redes tróficas en las AMP de la Isla Santa Rosa mostraron una estabilidad temporal mayor que en los sitios de referencia, probablemente debido a la reducción en la sincronía de presas. Entre las islas, la competencia a veces fue mayor y la depredación siempre fue mayor en las AMP comparadas con los sitios de referencia. Los incrementos en la fuerza de interacción causaron una menor estabilidad temporal en las redes tróficas. Aunque las AMP redujeron la sincronía de presas a nivel meta-comunitario, las reducciones no fueron suficientes para estabilizar las redes tróficas. Por el contrario, la variación temporal de la temperatura en la superficie marina tuvo grandes efectos positivos directos sobre la estabilidad a nivel regional y efectos indirectos a escala local por medio de reducciones en la fuerza de interacción entre las especies. Aunque las AMP pueden ser una estrategia efectiva de manejo para proteger ciertas especies o localidades, nuestros hallazgos en esta red de AMP sugieren que la variación térmica tiene una influencia más fuerte sobre la estabilidad temporal metacomunitaria cuando regula las interacciones entre especies y promueve un mosaico de variación espaciotemporal en la estructura comunitaria de las redes tróficas. Cuando se captura el espectro completo de variación ambiental en la planeación de redes, las AMP logran tener la capacidad máxima para promover la estabilidad del ecosistema como respuesta al cambio climático.

The impacts of artificial light at night on the ecology of temperate and tropical reefs.

Despite 22% of the world's coastal regions experiencing some degree of light pollution, and biologically important artificial light at night (ALAN) reaching large portions of the seafloor (greater than 75%) near coastal developments, the impacts of ALAN on temperate and tropical reefs are still relatively unknown. Because many reef species have evolved in response to low-light nocturnal environments, consistent daily, lunar, and seasonal light cycles, and distinct light spectra, these impacts are likely to be profound. Recent studies have found ALAN can decrease reproductive success of fishes, alter predation rates of invertebrates and fishes, and impact the physiology and biochemistry of reef-building corals. In this paper, we integrate knowledge of the role of natural light in temperate and tropical reefs with a synthesis of the current literature on the impacts of ALAN on reef organisms to explore potential changes at the system level in reef communities exposed to ALAN. Specifically, we identify the direct impacts of ALAN on individual organisms and flow on effects for reef communities, and present potential scenarios where ALAN could significantly alter system-level dynamics, possibly even creating novel ecosystems. Lastly, we highlight large knowledge gaps in our understanding of the overall impact of ALAN on reef systems. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Habitat attributes mediate herbivory and influence community development in algal metacommunities.

Understanding the drivers and impacts of spatiotemporal variation in species abundance on community trajectories is key to understanding the factors contributing to ecosystem resilience. Temporal variation in species trajectories across patches can provide compensation for species loss and can influence successional patterns. However, little is known about the underlying mechanisms that lead to patterns of species or spatial compensation and how those patterns may be mediated by consumer-resource relationships. Here we describe an experiment testing whether habitat attributes (e.g., structural complexity and spatial heterogeneity) mediate the effects of herbivory on tropical marine macroalgal communities by reducing accessibility and detectability, respectively, leading to variable trajectories among algal species at community (within patch) and metacommunity (i.e., among patch) scales. Reduced accessibility (greater habitat complexity) decreased the effects of herbivory (i.e., depressed consumption rate, increased algal species richness), and both accessibility and detectability (spatial heterogeneity) influenced algal community structure. Moreover, decreased accessibility at the community scale and a mosaic of accessibility at the metacommunity scale led to variation in community assembly. We suggest that habitat attributes can be important influencers of consumer-resource interactions on coral reefs, which in turn can increase species diversity, promote species succession, and enhance stability in algal metacommunities.

The coastal protection and blue carbon benefits of hybrid mangrove living shorelines.

Hybrid living shorelines use a combination of engineered structures with natural ecosystems to achieve coastal protection and habitat restoration outcomes, with added co-benefits such as carbon sequestration. Rock fillets constructed along eroding estuarine banks are designed to accumulate sediment, establish mangroves, and stabilise the shoreline. There is, however, a lack of data to support whether rock fillets are achieving these goals. We used a chronosequence of rock fillets to determine their effect on mangrove development, bank stabilisation and carbon sequestration in four estuaries in New South Wales, Australia. Aboveground biomass and adult density increased with age of rock fillets, and mangrove structure was similar to a natural fringing mangrove after 15 years. The rock fillets accumulated sediment, which reduced the eroded estuary bank height, however, little effect of the fillets on bank slope was observed. Sediment carbon stocks were not different between rock fillets, eroding estuary banks and natural fringing mangroves. Rock fillet design had a significant effect on mangrove structure and coastal protection function, with greater wave transmission through lower rock fillets, suggesting design optimisation is needed. As the construction cost of the rock fillets was equal or less than traditional rock revetments, where suitable they present a more economic and environmentally sustainable solution to estuarine erosion management.

Greater Consideration of Animals Will Enhance Coastal Restoration Outcomes.

As efforts to restore coastal habitats accelerate, it is critical that investments are targeted to most effectively mitigate and reverse habitat loss and its impacts on biodiversity. One likely but largely overlooked impediment to effective restoration of habitat-forming organisms is failing to explicitly consider non-habitat-forming animals in restoration planning, implementation, and monitoring. These animals can greatly enhance or degrade ecosystem function, persistence, and resilience. Bivalves, for instance, can reduce sulfide stress in seagrass habitats and increase drought tolerance of saltmarsh vegetation, whereas megaherbivores can detrimentally overgraze seagrass or improve seagrass seed germination, depending on the context. Therefore, understanding when, why, and how to directly manipulate or support animals can enhance coastal restoration outcomes. In support of this expanded restoration approach, we provide a conceptual framework, incorporating lessons from structured decision-making, and describe potential actions that could lead to better restoration outcomes using case studies to illustrate practical approaches.

Nature-based solutions for atoll habitability.

Atoll societies have adapted their environments and social systems for thousands of years, but the rapid pace of climate change may bring conditions that exceed their adaptive capacities. There is growing interest in the use of 'nature-based solutions' to facilitate the continuation of dignified and meaningful lives on atolls through a changing climate. However, there remains insufficient evidence to conclude that these can make a significant contribution to adaptation on atolls, let alone to develop standards and guidelines for their implementation. A sustained programme of research to clarify the potential of nature-based solutions to support the habitability of atolls is therefore vital. In this paper, we provide a prospectus to guide this research programme: we explain the challenge climate change poses to atoll societies, discuss past and potential future applications of nature-based solutions and outline an agenda for transdisciplinary research to advance knowledge of the efficacy and feasibility of nature-based solutions to sustain the habitability of atolls. This article is part of the theme issue 'Nurturing resilient marine ecosystems'.

How moonlight shapes environments, life histories, and ecological interactions on coral reefs.

The lunar cycle drives variation in nocturnal brightness. For the epipelagic larvae of coral reef organisms, nocturnal illumination may have widespread and underappreciated consequences. At sea, the onset of darkness coincides with an influx of mesopelagic organisms to shallow water (i.e. 'diel vertical migrants') that include predators (e.g. lanternfishes) and prey (zooplankton) of zooplanktivorous coral reef larvae. Moonlight generally suppresses this influx, but lunar periodicity in the timing and intensity of nocturnal brightness may affect vertically migrating predators and prey differently. A major turnover of species occurs at sunset on the reef, with diurnal species seeking shelter and nocturnal species emerging to hunt. The hunting ability of nocturnal reef-based predators is aided by the light of the moon. Consequently, variation in nocturnal illumination is likely to shape the timing of reproduction, larval development, and settlement for many coral reef organisms. This synthesis underscores the potential importance of trophic linkages between coral reefs and adjacent pelagic ecosystems, facilitated by the diel migrations of mesopelagic organisms and the ontogenetic migrations of coral reef larvae. Research is needed to better understand the effects of lunar cycles on life-history strategies, and the potentially disruptive effects of light pollution, turbidity, and climate-driven changes to nocturnal cloud cover. These underappreciated threats may alter patterns of nocturnal illumination that have shaped the evolutionary history of many coral reef organisms, with consequences for larval survival and population replenishment that could rival or exceed other effects arising from climate change.

A review of sediment carbon sampling methods in mangroves and their broader impacts on stock estimates for blue carbon ecosystems.

Blue carbon ecosystems (BCEs), such as mangroves, tidal marshes, and seagrasses, are attracting interest for their potential to mitigate climate change arising from their high rates of carbon accumulation and the significant carbon stocks in their sediments. However, current sediment carbon sampling methods present a mixture of approaches adopted from paleoenvironmental methods focused on historical reconstruction of carbon accumulation, and from soil science methods developed to provide highly accurate and spatially representative carbon stock measurements. Currently, no international standard method for sediment carbon stock analysis exists. Consequently, current estimates of sediment carbon stock values for BCEs may have large uncertainties due to variable methodology. We reviewed and analysed the methods used 217 studies included in two recent global syntheses of carbon stocks in mangrove forest ecosystems to illustrate a lack of consistency in sediment sampling. We then outline how the choice of study design and field sampling methods can introduce inaccuracies and uncertainties in sediment carbon stock analysis. We conclude with examples of how each of these challenges can be resolved and how greater carbon stock quantification accuracy and higher spatial integration can be achieved for blue carbon ecosystems in the future.

Light pollution: a landscape-scale issue requiring cross-realm consideration.

Terrestrial, marine and freshwater realms are inherently linked through ecological, biogeochemical and/or physical processes. An understanding of these connections is critical to optimise management strategies and ensure the ongoing resilience of ecosystems. Artificial light at night (ALAN) is a global stressor that can profoundly affect a wide range of organisms and habitats and impact multiple realms. Despite this, current management practices for light pollution rarely consider connectivity between realms. Here we discuss the ways in which ALAN can have cross-realm impacts and provide case studies for each example discussed. We identified three main ways in which ALAN can affect two or more realms: 1) impacts on species that have life cycles and/or stages in two or more realms, such as diadromous fish that cross realms during ontogenetic migrations and many terrestrial insects that have juvenile phases of the life cycle in aquatic realms; 2) impacts on species interactions that occur across realm boundaries, and 3) impacts on transition zones or ecosystems such as mangroves and estuaries. We then propose a framework for cross-realm management of light pollution and discuss current challenges and potential solutions to increase the uptake of a cross-realm approach for ALAN management. We argue that the strengthening and formalisation of professional networks that involve academics, lighting practitioners, environmental managers and regulators that work in multiple realms is essential to provide an integrated approach to light pollution. Networks that have a strong multi-realm and multi-disciplinary focus are important as they enable a holistic understanding of issues related to ALAN.

Testing the efficacy of sea urchin exclusion methods for restoring kelp.

Kelps are ecosystem engineers, which collectively form forests that provide a variety of important ecosystem services for humans and other organisms. Kelp forests are threatened by multiple local and global stressors, one of the most notable is herbivory. Overabundant sea; urchins can consume kelp, leading to a phase shift from productive forests to unproductive; rocky barrens. Reducing sea urchin densities by directly removing them can reverse this; phase shift. However, maintaining low densities of sea urchins, is logistically and financially; challenging. Following a review of herbivore exclusion methods to date, we tested the efficacy of three different methods for excluding sea urchins from kelp in the laboratory: flexible fences; electricity; and copper anti-fouling paint. The results from the laboratory; experiment showed that flexible fencing was the most successful method for excluding sea urchins. To test the efficacy of this method in the field, sea urchins were removed from 1m2 patches in barrens and intact kelp beds, and the effectiveness of flexible fences of two different heights (30 cm and 60 cm) at excluding sea urchins were tested. The results from the field study demonstrated that flexible fences of both heights were effective at maintaining low sea urchin densities in barrens but not in intact kelp beds, relative to unmanipulated; rocky barrens. These findings suggest that flexible fencing could be an important tool in restoring kelp in barrens, however the costs of fencing are likely to place limits on the scale at which this management strategy can be implemented.

Long-term exposure to artificial light at night in the wild decreases survival and growth of a coral reef fish.

Artificial light at night (ALAN) is an increasing anthropogenic pollutant, closely associated with human population density, and now well recognized in both terrestrial and aquatic environments. However, we have a relatively poor understanding of the effects of ALAN in the marine realm. Here, we carried out a field experiment in the coral reef lagoon of Moorea, French Polynesia, to investigate the effects of long-term exposure (18-23 months) to chronic light pollution at night on the survival and growth of wild juvenile orange-fin anemonefish, Amphiprion chrysopterus. Long-term exposure to environmentally relevant underwater illuminance (mean: 4.3 lux), reduced survival (mean: 36%) and growth (mean: 44%) of juvenile anemonefish compared to that of juveniles exposed to natural moonlight underwater (mean: 0.03 lux). Our study carried out in an ecologically realistic situation in which the direct effects of artificial lighting on juvenile anemonefish are combined with the indirect consequences of artificial lighting on other species, such as their competitors, predators, and prey, revealed the negative impacts of ALAN on life-history traits. Not only are there immediate impacts of ALAN on mortality, but the decreased growth of surviving individuals may also have considerable fitness consequences later in life. Future studies examining the mechanisms behind these findings are vital to understand how organisms can cope and survive in nature under this globally increasing pollutant.

Large-scale variation in wave attenuation of oyster reef living shorelines and the influence of inundation duration.

One of the paramount goals of oyster reef living shorelines is to achieve sustained and adaptive coastal protection, which requires meeting ecological (i.e., develop a self-sustaining oyster population) and engineering (i.e., provide coastal defense) targets. In a large-scale comparison along the Atlantic and Gulf coasts of the United States, the efficacy of various designs of oyster reef living shorelines at providing wave attenuation was evaluated accounting for the ecological limitations of oysters with regard to inundation duration. A critical threshold for intertidal oyster reef establishment is 50% inundation duration. Living shorelines that spent less than one-half of the time (<50%) inundated were not considered suitable habitat for oysters, however, were effective at wave attenuation (68% reduction in wave height). Reefs that experienced >50% inundation were considered suitable habitat for oysters, but wave attenuation was similar to controls (no reef; ~5% reduction in wave height). Many of the oyster reef living shoreline approaches therefore failed to optimize the ecological and engineering goals. In both inundation regimes, wave transmission decreased with an increasing freeboard (difference between reef crest elevation and water level), supporting its importance in the wave attenuation capacity of oyster reef living shorelines. However, given that the reef crest elevation (and thus freeboard) should be determined by the inundation duration requirements of oysters, research needs to be refocused on understanding the implications of other reef parameters (e.g., width) for optimizing wave attenuation. A broader understanding of the reef characteristics and seascape contexts that result in effective coastal defense by oyster reefs is needed to inform appropriate design and implementation of oyster-based living shorelines globally.

Lunar rhythms in growth of larval fish.

Growth and survival of larval fishes is highly variable and unpredictable. Our limited understanding of this variation constrains our ability to forecast population dynamics and effectively manage fisheries. Here we show that daily growth rates of a coral reef fish (the sixbar wrasse, Thalassoma hardwicke) are strongly lunar-periodic and predicted by the timing of nocturnal brightness: growth was maximized when the first half of the night was dark and the second half of the night was bright. Cloud cover that obscured moonlight facilitated a 'natural experiment', and confirmed the effect of moonlight on growth. We suggest that lunar-periodic growth may be attributable to light-mediated suppression of diel vertical migrations of predators and prey. Accounting for such effects will improve our capacity to predict the future dynamics of marine populations, especially in response to climate-driven changes in nocturnal cloud cover and intensification of artificial light, which could lead to population declines by reducing larval survival and growth.

Revision of the genus Hannia (Teleostei, Terapontidae), with description of a new species, Hannia wintoni, from the Kimberley, Western Australia.

The systematics of the genus Hannia Vari 1978, endemic to freshwater habitats of remote north-western Australia, is revised in light of recent collections in the region and a molecular study of the group that identified an undescribed candidate species. A new freshwater fish species (Hannia wintoni sp. nov) is described based on analysis of multiple nuclear genetic markers (53 allozyme loci), mitochondrial DNA sequence data (601 bp cytochrome b) and morphology (examination of a suite of 66 morphometric and meristic characters). Head profile, postorbital length, maximum length, preopercular spines and pectoral-fin rays are characters that best distinguish H. wintoni sp. nov from its only congener, H. greewayi. While the existing description of H. greenwayi is robust and accurate, we present a number of additional characters that enhance to the original description, based on type and fresh material. Information on the known distribution, habitats and conservation status of the two species is summarised. The new species is a narrow-range endemic.

Native predator limits the capacity of an invasive seastar to exploit a food-rich habitat.

Biodiverse ecosystems are sometimes inherently resistant to invasion, but environmental change can facilitate invasion by disturbing natural communities and providing resources that are underutilised by native species. In such cases, sufficiently abundant native predators may help to limit invasive population growth. We studied native and invasive seastars feeding under two mussel aquaculture sites in south-east Australia, to determine whether food-rich farm habitats are likely to be reproductive hotspots for the invasive seastar (Asterias amurensis) and whether the larger native seastar (Coscinasterias muricata) reduces the value of the farms for the invader. We found that invaders were not significantly more abundant inside the farms, despite individuals residing within the farms having higher body condition metrics and reproductive investment than those outside. By contrast, the native seastar was 25 × more abundant inside the two farms than outside. We observed several intraguild predation events and an absence of small invaders at the farms despite reports of high larval recruitment to these environments, consistent with some level of biotic control by the native predator. A laboratory choice experiment showed that invaders were strongly attracted to mussels except when the native predator was present. Together, these findings indicate that a combination of predation and predator evasion may play a role in reducing the value of food-rich anthropogenic habitats for this invasive species.

Reproductive phenology across the lunar cycle: parental decisions, offspring responses, and consequences for reef fish.

Most organisms reproduce in a dynamic environment, and life-history theory predicts that this can favor the evolution of strategies that capitalize on good times and avoid bad times. When offspring experience these environmental changes, fitness can depend strongly upon environmental conditions at birth and at later life stages. Consequently, fitness will be influenced by the reproductive decisions of parents (i.e., birth date effects) and developmental decisions (e.g., adaptive plasticity) of their offspring. We explored the consequences of these decisions using a highly iteroparous coral reef fish (the sixbar wrasse, Thalassoma hardwicke) and in a system where both parental and offspring environments vary with the lunar cycle. We tested the hypotheses that (1) reproductive patterns and offspring survival vary across the lunar cycle and (2) offspring exhibit adaptive plasticity in development time. We evaluated temporal variation in egg production from February to June 2017, and corresponding larval developmental histories (inferred from otolith microstructure) of successful settlers and surviving juveniles that were spawned during that same period. We documented lunar-cyclic variation in egg production (most eggs were spawned at the new moon). This pattern was at odds with the distribution of birth dates of settlers and surviving juveniles-most individuals that successfully survived to settlement and older stages were born during the full moon. Consequently, the probability of survival across the larval stage was greatest for offspring born close to the full moon, when egg production was at its lowest. Offspring also exhibited plasticity in developmental duration, adjusting their age at settlement to settle during darker portions of the lunar cycle than expected given their birth date. Offspring born near the new moon tended to be older and larger at settlement, and these traits conveyed a strong fitness advantage (i.e., a carryover effect) through to adulthood. We speculate that these effects (1) are shaped by a dynamic landscape of risk and reward determined by moonlight, which differentially influences adults and offspring, and (2) can explain the evolution of extreme iteroparity in sixbars.

Testing the adaptive advantage of a threatened species over an invasive species using a stochastic population model.

Introduced species are a major threat to freshwater biodiversity. Often eradication is not feasible, and management must focus on reducing impacts on native wildlife. This requires an understanding of how native species are affected but also how environmental characteristics influence population dynamics of both invasive and native species. Such insights can inform how to manipulate systems in order to take advantage of life-history traits native species possesses that invaders do not. The highly invasive fish, Gambusia holbrooki, has been implicated in the decline of many freshwater fish and amphibians. In south-eastern Australia, one of these is the threatened native fish, Galaxiella pusilla. As G. pusilla can survive periods without surface water, this presents an opportunity for adaptive management, given G. holbrooki lack these adaptations. We develop a stochastic population model to explore the impact of G. holbrooki on G. pusilla and test the feasibility of both natural and management-induced drying to protect this species. Our results support recent empirical studies showing G. holbrooki are a serious threat to G. pusilla persistence, especially through impacts on larval survival. While persistence is more likely in water bodies that frequently dry out, even optimal natural drying regimes may be insufficient when impacts from G. holbrooki are high. However, management-induced drying may allow persistence of G. pusilla in sites inhabited by both species. Given our model outcomes, the biology of these species and the habitats they occupy, we recommend maintaining or restoring aquatic and riparian vegetation and natural drying regimes to protect G. pusilla from G. holbrooki, in addition to undertaking management-induced drying of invaded water bodies. Our results provide insights into how the effects of G. holbrooki may be mitigated for other native species, which is important given this species is perhaps the most pervasive invader of freshwater ecosystems. We conclude with a discussion of the potential for using disturbance processes in the management of invasive species more broadly in freshwater and terrestrial systems.

In situ 3D visualization of biomineralization matrix proteins.

Calcium biominerals occur in all major animal phyla, and through biomolecular control, exhibit such diverse structures as exoskeletons, shells, bones, teeth and earstones (otoliths). Determining the three-dimensional expression of key biomineral proteins, however, has proven challenging as typical protein identification methods either lose spatial resolution during dissolution of the mineral phase or are costly and limited to two-dimensional expression of high abundance proteins. Here we present a modification of the CLARITY and ACT-PRESTO protocols to visualize and confirm, for the first time, the timing of expression and function of two key regulators of biomineralization.