Integrating larval connectivity into the marine conservation decision-making process across spatial scales.

Larval dispersal connectivity is typically integrated into spatial conservation decisions at regional or national scales, but implementing agencies struggle with translating these methods to local scales. We used larval dispersal connectivity at regional (hundreds of kilometers) and local (tens of kilometers) scales to aid in design of networks of no-take reserves in Southeast Sulawesi, Indonesia. We used Marxan with Connectivity informed by biophysical larval dispersal models and remotely sensed coral reef habitat data to design marine reserve networks for 4 commercially important reef species across the region. We complemented regional spatial prioritization with decision trees that combined network-based connectivity metrics and habitat quality to design reserve boundaries locally. Decision trees were used in consensus-based workshops with stakeholders to qualitatively assess site desirability, and Marxan was used to identify areas for subsequent network expansion. Priority areas for protection and expected benefits differed among species, with little overlap in reserve network solutions. Because reef quality varied considerably across reefs, we suggest reef degradation must inform the interpretation of larval dispersal patterns and the conservation benefits achievable from protecting reefs. Our methods can be readily applied by conservation practitioners, in this region and elsewhere, to integrate connectivity data across multiple spatial scales.

Integración de la conectividad larval al proceso de toma de decisiones en la conservación marina en escalas espaciales Resumen Comúnmente se integra la conectividad de la dispersión larval a las decisiones de conservación espacial a escalas regionales o nacionales, pero las agencias de implementación luchan con la transferencia de estos métodos a las escalas locales. Usamos la conectividad de la dispersión larval a escalas regionales (cientos de kilómetros) y locales (decenas de kilómetros) para ayudar en el diseño de redes de reservas con protección total en Sulawesi Sudoriental, Indonesia. Usamos Marxan con la conectividad guiada por los modelos biofísicos de dispersión larval y detectamos a distancia los datos de hábitat de los arrecifes de coral para diseñar redes de reservas marinas para cuatro especies de importancia comercial en la región. Complementamos la priorización espacial regional con árboles de decisión que combinaron medidas de conectividad basadas en las redes y la calidad del hábitat para diseñar localmente los límites de la reserva. Usamos los árboles de decisión con los actores en talleres basados en el consenso para evaluar cualitativamente la conveniencia del sitio. También usamos Marxan para identificar áreas para la expansión subsecuente de la red. Las áreas prioritarias para la protección y los beneficios esperados difirieron entre especies, con un traslape reducido en las soluciones de la red de reservas. Ya que la calidad del arrecife varió considerablemente entre los arrecifes, sugerimos que la degradación de estos debe orientar la interpretación de los patrones de dispersión larval y los beneficios de conservación alcanzables con la protección de los arrecifes. Los practicantes de la conservación pueden aplicar nuestros métodos inmediatamente, en esta región o en cualquier otra, para integrar los datos de conectividad en varias escalas espaciales.

Comparing spatial conservation prioritization methods with site- versus spatial dependency-based connectivity.

Larval dispersal is an important component of marine reserve networks. Two conceptually different approaches to incorporate dispersal connectivity into spatial planning of these networks exist, and it is an open question as to when either is most appropriate. Candidate reserve sites can be selected individually based on local properties of connectivity or on a spatial dependency-based approach of selecting clusters of strongly connected habitat patches. The first acts on individual sites, whereas the second acts on linked pairs of sites. We used a combination of larval dispersal simulations representing different seascapes and case studies of biophysical larval dispersal models in the Coral Triangle region and the province of Southeast Sulawesi, Indonesia, to compare the performance of these 2 methods in the spatial planning software Marxan. We explored the reserve design performance implications of different dispersal distances and patterns based on the equilibrium settlement of larvae in protected and unprotected areas. We further assessed different assumptions about metapopulation contributions from unprotected areas, including the case of 100% depletion and more moderate scenarios. The spatial dependency method was suitable when dispersal was limited, a high proportion of the area of interest was substantially degraded, or the target amount of habitat protected was low. Conversely, when subpopulations were well connected, the 100% depletion was relaxed, or more habitat was protected, protecting individual sites with high scores in metrics of connectivity was a better strategy. Spatial dependency methods generally produced more spatially clustered solutions with more benefits inside than outside reserves compared with site-based methods. Therefore, spatial dependency methods potentially provide better results for ecological persistence objectives over enhancing fisheries objectives, and vice versa. Different spatial prioritization methods of using connectivity are appropriate for different contexts, depending on dispersal characteristics, unprotected area contributions, habitat protection targets, and specific management objectives. Comparación entre los métodos de priorización de la conservación espacial con sitio y la conectividad espacial basada en la dependencia.

La dispersión larval es un componente importante de las redes de reservas marinas. Existen dos estrategias conceptualmente distintas para incorporar la conectividad de la dispersión en la planeación espacial de estas redes y es una pregunta abierta cuándo alguna de las dos es la más apropiada. Los sitios candidatos a reserva pueden ser seleccionados individualmente con base en las propiedades locales de la conectividad o en la estrategia espacial basada en la dependencia que consiste en seleccionar grupos de fragmentos de hábitat con un vínculo fuerte. La primera estrategia actúa sobre sitios individuales, mientras que la segunda actúa sobre pares de sitios vinculados. Usamos una combinación de simulaciones de dispersión larval que representaban a diferentes paisajes marinos y estudios de caso de modelos biofísicos de dispersión larval en la región del Triángulo de Coral y en la provincia de Sulawesi Sudoriental, Indonesia, para comparar el desempeño de estos dos métodos en el software de planeación espacial Marxan. Exploramos las implicaciones del desempeño del diseño de la reserva de diferentes distancias y patrones de dispersión basados en el establecimiento del equilibrio de larvas en las áreas protegidas y sin protección. Además, analizamos las suposiciones sobre las contribuciones metapoblacionales de las áreas sin protección, incluyendo el caso de la reducción al 100% y escenarios más moderados. El método de la dependencia espacial fue adecuado cuando la dispersión estuvo limitada, una proporción elevada del área de interés estaba sustancialmente degradada o era baja la cantidad meta de hábitat protegido. Al contrario, cuando las subpoblaciones estaban bien conectadas, la reducción al 100% estuvo relajada, o si una mayor parte del hábitat estaba protegido, la protección de los sitios individuales con altos puntajes en las medidas de conectividad fue una mejor estrategia. Los métodos de dependencia espacial generalmente produjeron soluciones con una agrupación más espacial y con más beneficios dentro que fuera de las reservas en comparación con los métodos basados sitios. Por lo tanto, los métodos de dependencia espacial tienen el potencial de proporcionar mejores resultados para los objetivos de persistencia ecológica por encima de los objetivos de mejora de las pesquerías, y viceversa. Los diferentes métodos de priorización espacial que usan la conectividad son apropiados para contextos diferentes, dependiendo de las características de dispersión, las contribuciones del área sin protección, las metas de protección del hábitat y los objetivos específicos del manejo.

Beyond the model: expert knowledge improves predictions of species' fates under climate change.

The need to proactively manage landscapes and species to aid their adaptation to climate change is widely acknowledged. Current approaches to prioritizing investment in species conservation generally rely on correlative models, which predict the likely fate of species under different climate change scenarios. Yet, while model statistics can be improved by refining modeling techniques, gaps remain in understanding the relationship between model performance and ecological reality. To investigate this, we compared standard correlative species distribution models to highly accurate, fine-scale, distribution models. We critically assessed the ecological realism of each species' model, using expert knowledge of the geography and habitat in the study area and the biology of the study species. Using interactive software and an iterative vetting with experts, we identified seven general principles that explain why the distribution modeling under- or overestimated habitat suitability, under both current and predicted future climates. Importantly, we found that, while temperature estimates can be dramatically improved through better climate downscaling, many models still inaccurately reflected moisture availability. Furthermore, the correlative models did not account for biotic factors, such as disease or competitor species, and were unable to account for the likely presence of micro refugia. Under-performing current models resulted in widely divergent future projections of species' distributions. Expert vetting identified regions that were likely to contain micro refugia, even where the fine-scale future projections of species distributions predicted population losses. Based on the results, we identify four priority conservation actions required for more effective climate change adaptation responses. This approach to improving the ecological realism of correlative models to understand climate change impacts on species can be applied broadly to improve the evidence base underpinning management responses.

Correction: Effects of microplastic exposure on the body condition and behaviour of planktivorous reef fish (Acanthochromis polyacanthus).

[This corrects the article DOI: 10.1371/journal.pone.0193308.].

Legacy community science data suggest reduced beached litter in response to a container deposit scheme at a local scale.

Marine debris is causing significant environmental harm. Legislation is being implemented to reduce litter, including schemes like container deposit legislation that incentivize the return of commonly littered items for recycling. While there is a suggestion that these schemes reduce litter, no study has examined the long-term impact on the local environment before and after implementation. This study analyses community science data from 8 years prior to the implementation of a container deposit scheme, paired with 3 years of data afterwards, to assess the scheme's effectiveness at a local scale. Although using legacy datasets limits the generalizability of the conclusions compared to dedicated studies, the findings strongly indicate that container deposit schemes effectively manage targeted containers but have little impact on overall waste abundances. Long-term datasets like these are invaluable for assessing the impact of management efforts.

How wide, how much? A framework for quantifying the economic and ecological outcomes of altering riparian width on agricultural land.

Creating and managing riparian buffer zones (RBZs) is regarded as a global best-practice management strategy for maintaining and improving waterway health. Agricultural land often utilises RBZs as highly productive pasture, exposing waterways to increased inputs of nutrients, pollutants, and sediment, in addition to reducing carbon sequestration and habitat for native flora and fauna. This project developed a novel approach to the application of multisystem ecological and economic quantification models to the property-scale, at low cost and high speed. We developed a state-of-the-art dynamic geospatial interface to communicate these outputs when switching from pasture to revegetated riparian zone via planned restoration efforts. The tool was developed using the regional conditions of a south-east Australian catchment as a case study but is designed to be adaptable around globally using equivalent model inputs. Ecological and economic outcomes were determined using existing methods, including an agricultural land suitability analysis to quantify primary production, an estimation of carbon sequestration using historic vegetation datasets and GIS software analysis to determine spatial costings of revegetation and fencing. Economic outcomes are presented in raw values of pasture produced and carbon sequestered, and fencing and revegetation costs can be easily altered for enhanced usability and interoperability. This tool can provide property-specific data for almost 16,000 properties in a catchment area of over 130,000 km2 and 19,600 km of river length. Our results indicated that current financial incentives for revegetation rarely cover the cost of giving up pasture, but these costs may be compensated by social and ecological outcomes achieved over time. This method provides a novel way of informing alternative management approaches, such as incremental revegetation plans and the selective harvesting of timber from RBZ. The model provides an innovative framework for improved RBZ management and can be used to inform property-specific responses and guide discussion among stakeholders.

Predicting the exposure of coastal species to plastic pollution in a complex island archipelago.

Plastic pollution in the marine environment is a pervasive and increasing threat to global biodiversity. Prioritising management actions that target marine plastic pollution require spatial information on the dispersal and settlement of plastics from both local and external sources. However, there is a mismatch between the scale of most plastic dispersal studies (regional, national and global) and the scale relevant to management action (local). We use a fine-resolution hydrodynamic model to predict the potential exposure of coastal habitats and species (mangroves, coral reefs and marine turtles) to plastic pollution at the local scale of a management region (the 1,700 km2 Whitsunday Islands, Queensland, Australia). We assessed the potential exposure of mangroves, coral reefs and marine turtles to plastics during the two dominant wind conditions of the region; the trade wind and monsoon wind seasons. We found that in the trade wind season (April to September) all habitats and species had lower exposure than during the monsoon wind season (October to March). In both wind seasons we found a small proportion of coral reef habitat and large area of turtle habitat were in high potential exposure categories. Unlike coral reefs or marine turtles, mangroves had consistent hotspots of high exposure across wind seasons. Local scale management requires data at fine resolution to capture the variability that occurs at this scale. The outputs of our study can inform the development of conservation resources and local scale management action.

Input of plastic debris in an urban tropical river system.

Land-based sources contribute approximately 80% of anthropogenic debris in marine environments. A main pathway is believed to be rivers and storm-water systems, yet this input is rarely quantified. We aimed to quantify the abundance of land-based debris entering a river system through storm drains in an urban area of tropical Australia. To account for seasonal variability, debris was quantified pre, post and during the wet season from 2014 to 2017. Plastic items within the river were compared to those in adjacent parks to assess similarities in debris composition. A total of 27,943 items were collected (92% plastic). Debris loads in the post-wet seasons were significantly higher than the wet-season. Furthermore, variability in the portion of debris found in nearby parks compared to the river suggests that factors other than rainfall, play a role in debris abundance. These results can be used to identify targeted management strategies to reduce debris loads.

Effects of microplastic exposure on the body condition and behaviour of planktivorous reef fish (Acanthochromis polyacanthus).

The effect of a pollutant on the base of the food web can have knock-on effects for trophic structure and ecosystem functioning. In this study we assess the effect of microplastic exposure on juveniles of a planktivorous fish (Acanthochromis polyacanthus), a species that is widespread and abundant on Indo-Pacific coral reefs. Under five different plastic concentration treatments, with plastics the same size as the natural food particles (mean 2mm diameter), there was no significant effect of plastic exposure on fish growth, body condition or behaviour. The amount of plastics found in the gastro-intestinal (GI) tract was low, with a range of one to eight particles remaining in the gut of individual fish at the end of a 6-week plastic-exposure period, suggesting that these fish are able to detect and avoid ingesting microplastics in this size range. However, in a second experiment the number of plastics in the GI tract vastly increased when plastic particle size was reduced to approximately one quarter the size of the food particles, with a maximum of 2102 small (< 300µm diameter) particles present in the gut of individual fish after a 1-week plastic exposure period. Under conditions where food was replaced by plastic, there was a negative effect on the growth and body condition of the fish. These results suggest plastics could become more of a problem as they break up into smaller size classes, and that environmental changes that lead to a decrease in plankton concentrations combined with microplastic presence is likely have a greater influence on fish populations than microplastic presence alone.

Does behaviour affect the dispersal of flatback post-hatchlings in the Great Barrier Reef?

The ability of individuals to actively control their movements, especially during the early life stages, can significantly influence the distribution of their population. Most marine turtle species develop oceanic foraging habitats during different life stages. However, flatback turtles (Natator depressus) are endemic to Australia and are the only marine turtle species with an exclusive neritic development. To explain the lack of oceanic dispersal of this species, we predicted the dispersal of post-hatchlings in the Great Barrier Reef (GBR), Australia, using oceanographic advection-dispersal models. We included directional swimming in our models and calibrated them against the observed distribution of post-hatchling and adult turtles. We simulated the dispersal of green and loggerhead turtles since they also breed in the same region. Our study suggests that the neritic distribution of flatback post-hatchlings is favoured by the inshore distribution of nesting beaches, the local water circulation and directional swimming during their early dispersal. This combination of factors is important because, under the conditions tested, if flatback post-hatchlings were entirely passively transported, they would be advected into oceanic habitats after 40 days. Our results reinforce the importance of oceanography and directional swimming in the early life stages and their influence on the distribution of a marine turtle species.