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'Natural' disasters (also known as geophysical disasters) involve physical processes that have a direct or indirect impact on humans. These events occur rapidly and may have severe consequences for resident flora and fauna as their habitat undergoes dramatic and sudden change. Although most studies have focused on the impact of natural disasters on humans and terrestrial systems, geophysical disasters can also impact aquatic ecosystems. Here, we provide a synthesis on the effects of the most common and destructive geophysical disasters on aquatic systems (life and habitat). Our approach spanned realms (i.e., freshwater, estuarine, and marine) and taxa (i.e., plants, vertebrates, invertebrates, and microbes) and included floods, droughts, wildfires, hurricanes/cyclones/typhoons, tornadoes, dust storms, ice storms, avalanches (snow), landslides, volcanic eruptions, earthquakes (including limnic eruptions), tsunamis, and cosmic events. Many geophysical disasters have dramatic effects on aquatic systems. The evidence base is somewhat limited for some natural disasters because transient events (e.g., tornadoes and floods) are difficult to study. Most natural disaster studies focus on geology/geomorphology and hazard assessment for humans and infrastructure. However, the destruction of aquatic systems can impact humans indirectly through loss of food security, cultural services, or livelihoods. Many geophysical disasters interact in complex ways (e.g., wildfires often lead to landslides and flooding) and can be magnified or otherwise mediated by human activities. Our synthesis reveals that geophysical events influence aquatic ecosystems, often in negative ways, yet systems can be resilient provided that effects are not compounded by anthropogenic stressors. It is difficult to predict or prevent geophysical disasters but understanding how aquatic ecosystems are influenced by geophysical events is important given the inherent connection between peoples and aquatic ecosystems. Key words: Geophysical disasters, natural disasters, natural hazards, aquatic ecosystems, ecosystem services, threats, Introduction 'Natural' disasters can be defined as 'some rapid, instantaneous or profound impact of the natural environment upon the socioeconomic system' (Alexander 2018) usually with a restricted temporal and spatial [...]

This study provides evidence of two subpopulations of Atlantic halibut (Hippoglossus hippoglossus) in the southern Gulf of St. Lawrence. The migrations of 20 Atlantic halibut captured in the coastal waters of Prince Edward Island, Canada, were evaluated using pop-up satellite archival tags (PSAT). Geolocation data showed that Atlantic halibut migrated north to the Laurentian Channel via distinct eastern or western routes. Floy tagging and recapture (recapture of 18.4%) showed that less than 7.0% of Atlantic halibut exhibited dispersive behaviour outside of their annual migratory route. Overwintering occurred on the slope and in the deepest waters of the Laurentian Channel. Atlantic halibut in the deepest waters of the Laurentian Channel exhibited rapid, ~100 m rises, presumed to be associated with spawning from January to March. The eastern and western migratory cohorts exhibited this behaviour ~350 km apart, suggesting reproductive isolation as the basis of subpopulations. The results of this study indicate a need to reconsider the management of Gulf of St. Lawrence Atlantic halibut as one continuous population. L'etude presente des preuves de la presence de deux sous-populations de fletans de l'Atlantique (Hippoglossus hippoglossus) dans le sud du golfe du Saint-Laurent. Les migrations de 20 fletans captures dans les eaux cotieres de rIle-du-Prince- Edouard (Canada) ont ete evaluees a l'aide d'etiquettes emettrices detachables (EED). Les donnees de geolocalisation montrent que les fletans migraient vers le nord jusqu'au chenal Laurentien par des voies est et ouest distinctes. Des donnees de recapture d'etiquettes Floy (18,4 % de recapture) montrent que moins de 7,0 % des fletans presentaient un comportement de dispersion en dehors de leur voie de migration annuelle. Les fletans passaient l'hiver sur la pente et dans les eaux les plus profondes du chenal Laurentien. Les fletans dans les eaux les plus profondes du chenal Laurentien effectuaient des remontees rapides de ~100 m, possiblement associees au frai de janvier a mars. Les cohortes migratrices est et ouest presentaient ce comportement a ~350 km de distance l'une de l'autre, donnant a penser que l'isolement aux fins de la reproduction est a l'origine des sous- populations. Les resultats de l'etude font ressortir la necessite de revoir l'approche de gestion du fletan de l'Atlantique dans le golfe du SaintLaurent basee sur une seule population continue. [Traduit par la Redaction], Introduction Observing how fish move across time and space can help define the boundaries of a population, improve our understanding of how adjacent populations interact, uncover critical times or regions [...]

This study examined the migratory patterns of introduced rainbow trout (Oncorhynchus mykiss) in three rivers in Prince Edward Island, Canada, using acoustic telemetry and otolith microchemistry. Only 6% of acoustically tagged fish in three river systems left coastal embayments. A cohort of rainbow trout in all three rivers entered saline waters. Habitat use differed among migrants in the three rivers, as Montague River fish occupied estuary habitat (mean 20.79 PSU) more often than West River and Dunk River fish that tended to occupy both riverine tidal (mean 1.27 and 4.29 PSU, respectively) and freshwater habitats ( L'etude se penche sur les habitudes migratoires de truites arc-en-ciel (Oncorhynchus mykiss) introduites dans trois rivieres de llle-du-Prmce-Edouard (Canada) en utilisant la telemetrie acoustique et la microchimie des otolites. Seuls 6 % des poissons dotes d'etiquettes acoustiques dans les trois reseaux hydrographiques ont quitte les echancrures cotieres. Une cohorte de truites arc-en-ciel dans chacune des trois rivieres est entree en eaux salees. L'utilisation de l'habitat variait entre les migrants des trois rivieres, les poissons de la riviere Montague occupant un habitat estuarien (20,79 USP en moyenne) plus souvent que les poissons des rivieres West et Dunk, qui avaient tendance a occuper des habitats fluviaux tidaux (1,27 et 4,29 USP en moyenne, respectivement) et d'eau douce (, Introduction Rainbow trout (Oncorhynchus mykiss) have been introduced to over 90 countries (MacCrimmon 1971; Crawford and Muir 2008), as the species is a valued recreational angling target. However, their impacts [...]