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1. Predicting climate change impacts on critical fisheries species in Fijian marine systems and its implications for protected area spatial planning

   https://doi.org/10.1111/ddi.13709  

   Lawson, Katherine N. ; Lang, Karina M. ; Rabaiotti, Daniella ; Drew, Joshua ( August 2023 , Diversity and Distributions)

   Spatially explicit protections of coastal habitats determined on the current distribution of species and ecosystems risk becoming obsolete in 100 years if the movement of species ranges outpaces management action. Hence, a critical step of conservation is predicting the efficacy of management actions in future. We aimed to determine how foundational, habitat‐building species will respond to climate change in Fiji.

   The Republic of Fiji.

   We develop species distribution models (SDMs) using MaxEnt, General Additive Models and Boosted Regression Trees and publicly available data from the Global Biodiversity Information Facility to predict changes in distribution of suitable habitat for mangrove forests, coral habitat, seagrass meadows and critical fisheries invertebrates under several IPCC climate change scenarios in 2070 or 2100. We then overlay predicted distribution models onto existing Fijian protected area network to assess whether today's conservation measures will afford protection to tomorrow's distributions.

   We found that mangrove suitability is projected to decrease along the Coral Coast and increase northward towards the Yasawa Islands due to precipitation changes. The response of seagrass meadows was predicted to be inconsistent and dependent on the climate scenario. Meanwhile, suitability for coral reefs was not predicted to decline significantly overall. The mangrove crabScylla serrata, an important resource for fisherwomen in Fiji, is projected to increase in habitat suitability while economically important sea cucumber species will have highly variable responses to climate change.

   Species distribution models are a critical tool for conservation managers, as linking spatial distribution data with future climate change scenarios can aid in the creation and resiliency of protected area programmes. New protected area designations should consider the future distribution of species to maximize benefits to those taxa.

    

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2. Rapidly Changing Range Limits in a Warming World: Critical Data Limitations and Knowledge Gaps for Advancing Understanding of Mangrove Range Dynamics in the Southeastern USA

   https://doi.org/10.1007/s12237-023-01209-7  

   Bardou, Rémi ; Osland, Michael J. ; Scyphers, Steven ; Shepard, Christine ; Aerni, Karen E. ; Alemu I, Jahson B. ; Crimian, Robert ; Day, Richard H. ; Enwright, Nicholas M. ; Feher, Laura C. ; et al ( July 2023 , Estuaries and Coasts)

   Abstract Climate change is altering species’ range limits and transforming ecosystems. For example, warming temperatures are leading to the range expansion of tropical, cold-sensitive species at the expense of their cold-tolerant counterparts. In some temperate and subtropical coastal wetlands, warming winters are enabling mangrove forest encroachment into salt marsh, which is a major regime shift that has significant ecological and societal ramifications. Here, we synthesized existing data and expert knowledge to assess the distribution of mangroves near rapidly changing range limits in the southeastern USA. We used expert elicitation to identify data limitations and highlight knowledge gaps for advancing understanding of past, current, and future range dynamics. Mangroves near poleward range limits are often shorter, wider, and more shrublike compared to their tropical counterparts that grow as tall forests in freeze-free, resource-rich environments. The northern range limits of mangroves in the southeastern USA are particularly dynamic and climate sensitive due to abundance of suitable coastal wetland habitat and the exposure of mangroves to winter temperature extremes that are much colder than comparable range limits on other continents. Thus, there is need for methodological refinements and improved spatiotemporal data regarding changes in mangrove structure and abundance near northern range limits in the southeastern USA. Advancing understanding of rapidly changing range limits is critical for foundation plant species such as mangroves, as it provides a basis for anticipating and preparing for the cascading effects of climate-induced species redistribution on ecosystems and the human communities that depend on their ecosystem services. 

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3. Impacts of Climate Change on Marine Foundation Species

   https://doi.org/10.1146/annurev-marine-042023-093037  

   Wernberg, Thomas ; Thomsen, Mads S. ; Baum, Julia K. ; Bishop, Melanie J. ; Bruno, John F. ; Coleman, Melinda A. ; Filbee-Dexter, Karen ; Gagnon, Karine ; He, Qiang ; Murdiyarso, Daniel ; et al ( January 2024 , Annual Review of Marine Science)

   Marine foundation species are the biotic basis for many of the world's coastal ecosystems, providing structural habitat, food, and protection for myriad plants and animals as well as many ecosystem services. However, climate change poses a significant threat to foundation species and the ecosystems they support. We review the impacts of climate change on common marine foundation species, including corals, kelps, seagrasses, salt marsh plants, mangroves, and bivalves. It is evident that marine foundation species have already been severely impacted by several climate change drivers, often through interactive effects with other human stressors, such as pollution, overfishing, and coastal development. Despite considerable variation in geographical, environmental, and ecological contexts, direct and indirect effects of gradual warming and subsequent heatwaves have emerged as the most pervasive drivers of observed impact and potent threat across all marine foundation species, but effects from sea level rise, ocean acidification, and increased storminess are expected to increase. Documented impacts include changes in the genetic structures, physiology, abundance, and distribution of the foundation species themselves and changes to their interactions with other species, with flow-on effects to associated communities, biodiversity, and ecosystem functioning. We discuss strategies to support marine foundation species into the Anthropocene, in order to increase their resilience and ensure the persistence of the ecosystem services they provide.

    

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4. Assessing the reliability of species distribution models in the face of climate and ecosystem regime shifts: Small pelagic fishes in the California Current System

   https://doi.org/10.3389/fmars.2022.711522  

   Asch, Rebecca G. ; Sobolewska, Joanna ; Chan, Keo ( August 2022 , Frontiers in Marine Science)

   Species distribution models (SDMs) are a commonly used tool, which when combined with earth system models (ESMs), can project changes in organismal occurrence, abundance, and phenology under climate change. An often untested assumption of SDMs is that relationships between organisms and the environment are stationary. To evaluate this assumption, we examined whether patterns of distribution among larvae of four small pelagic fishes (Pacific sardine Sardinops sagax , northern anchovy Engraulis mordax , jack mackerel Trachurus symmetricus , chub mackerel Scomber japonicus ) in the California Current remained steady across time periods defined by climate regimes, changes in secondary productivity, and breakpoints in time series of spawning stock biomass (SSB). Generalized additive models (GAMs) were constructed separately for each period using temperature, salinity, dissolved oxygen (DO), and mesozooplankton volume as predictors of larval occurrence. We assessed non-stationarity based on changes in six metrics: 1) variables included in SDMs; 2) whether a variable exhibited a linear or non-linear form; 3) rank order of deviance explained by variables; 4) response curve shape; 5) degree of responsiveness of fishes to a variable; 6) range of environmental variables associated with maximum larval occurrence. Across all species and time periods, non-stationarity was ubiquitous, affecting at least one of the six indicators. Rank order of environmental variables, response curve shape, and oceanic conditions associated with peak larval occurrence were the indicators most subject to change. Non-stationarity was most common among regimes defined by changes in fish SSB. The relationships between larvae and DO were somewhat more likely to change across periods, whereas the relationships between fishes and temperature were more stable. Respectively, S. sagax , T. symmetricus , S. japonicus , and E. mordax exhibited non-stationarity across 89%, 67%, 50%, and 50% of indicators. For all species except E. mordax , inter-model variability had a larger impact on projected habitat suitability for larval fishes than differences between two climate change scenarios (SSP1-2.6 and SSP5-8.5), implying that subtle differences in model formulation could have amplified future effects. These results suggest that the widespread non-stationarity in how fishes utilize their environment could hamper our ability to reliably project how species will respond to climatic change. 

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5. Assessing historical and future habitat models for four conservation‐priority Mojave Desert species

   https://doi.org/10.1111/jbi.13645  

   Guida, Ross J. ; Abella, Scott R. ; Roberts, Chris L. ; Norman, Carrie M. ; Smith, Jr., William J. ( June 2019 , Journal of Biogeography)

   Modelling and quantifying habitat changes using three historical field surveys for four Mojave Desert species and projecting future scenarios.

   Newberry Mountains, southern Nevada, USA.

   Three vegetation field surveys were conducted, ending in 1979, 2008 and 2016, respectively. Field data collection across three time steps resulted in a unique dataset with 100 re‐surveyed 0.06‐ha plots. Using Maxent ecological niche modelling and 800‐m resolution Parameter Elevation Regressions on Independent Slopes Model (PRISM) temperature and precipitation data, habitat was assessed for four high‐elevation species. Recognizing that missing location data is a common challenge in species distribution modelling, sensitivity analysis was conducted utilizing three high‐elevation plots that species inhabited during the first two field surveys but that were unable to be sampled in 2016. Area under the curve for three species’ model runs exceeded 0.95, while one wider‐distributed species exceeded 0.79 for all runs. Future scenarios were also modelled under temperature increases and 16% and 0% reductions in precipitation.

   The number of presence locations and densities forJuniperus californica,Pinus monophylla,Quercus turbinellaandYucca schidigeradecreased from 1979 to 2016, while their average elevational distribution increased. Using the 100 plots measured each of the three study years, models for all four species indicated decreases in potential suitable habitat ranging from 10% to 45%. When including the three highest elevation plots not re‐sampled in 2016, but likely still containing the modelled species, modelled habitat loss ranged from 0% to 29%. Future model projections show drastic reductions in the suitable habitat of all four modelled species.

   While many Maxent ecological modelling studies have been conducted, few have incorporated repeat surveys of identical plots as in our study. Model projections using a unique 100‐plot dataset suggest that suitable habitat area is contracting for the species studied, and this correlated with climatic warming and drying in the Mojave Desert. Despite model projections that show nearly complete loss of suitable habitat in 2053, care should be taken given uncertain estimates of the velocity of climate change and the slower pace of habitat contractions measured in the field.

    

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