Larval dispersal is arguably the most important but least understood demographic process in the sea. The likelihood of a larva dispersing from its birthplace to successfully recruit in another location is the culmination of many intrinsic and extrinsic factors that operate in early life. Empirically estimating the resulting population connectivity has been immensely difficult because of the challenges of studying and quantifying dispersal in the sea. Consequently, most estimates are based on predictions from biophysical models. Although there is a long history of dispersal modelling, there has been no comprehensive review of this literature. We conducted a systematic quantitative review to address the following questions: (1) Is there any bias in the distribution of research effort based on geographical or taxonomic coverage? (2) Are hydrodynamic models resolving ocean circulation at spatial scales (resolution and extent) relevant to the dispersal process under study? (3) Where, when and how many particles are being tracked, and is this effort sufficient to capture the spatiotemporal variability in dispersal? (4) How is biological and/or behavioural complexity incorporated into Lagrangian particle tracking models. (i.e. are key attributes of the dispersal process well captured.)? Our review confirms strong taxonomic and geographic biases in published work to date. We found that computational 'effort' (i.e. model resolution and particle number) has not kept pace with dramatic increases in computer processor speed. We also identified a number of shortcomings in the incorporation of biology, and behaviour specifically into models. Collectively, these findings highlight some important gaps and key areas for improvement of biophysical models that aspire to inform larval dispersal processes. In particular, we suggest the need for greater emphasis on validation of model assumptions, as well as testing of dispersal predictions with empirically derived data.

Dispersal is a critically important process that dictates population persistence, gene flow, and evolutionary potential, and is an essential element for identifying species conservation risks. This study aims to investigate the contributions of dispersal syndromes and hydrographic barriers on patterns of population connectivity and genetic structure in fishes occupying the particularly rugged and fragmented landscape of the Kimberley Plateau, Western Australia. We assessed population genetic structure between three neighbouring catchments (the Mitchell, King Edward, and Drysdale rivers) in three congeneric groups of freshwater fishes that exhibit varied dispersal syndromes within and among groups: (1) Melanotaenia australis and M. gracilis; (2) Syncomistes trigonicus and S. rastellus; and (3) Hephaestus jenkinsi and H. epirrhinos. Within each species we sampled the upper, middle, and lower reaches of each catchment and assessed patterns of gene flow between and within catchments using microsatellite markers. Our results suggest that contemporary connectivity between catchments is greatly limited or absent in all study species, regardless of their dispersal syndromes. However, gene flow within catchments varied in line with predicted dispersal potential, with poor dispersers exhibiting limited gene flow and significant genetic structuring. We conclude that the rugged landscape and historical habitat isolation has contributed to patterns of population fragmentation among fish populations from different river catchments. However, it appears dispersal syndromes influence connectivity and gene flow within catchments, where landscape constraints are not as pervasive. This study presents a comparative population genetic analysis of freshwater fishes with differing dispersal syndromes and colonisation ability. Our findings provide new insights into factors shaping patterns of biodiversity on the Kimberley Plateau, and the evolutionary uniqueness of fish communities from different river catchments draining the plateau. More broadly, they highlight the importance of accounting for dispersal‐related traits when planning management and conservation strategies.

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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.

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