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Abstract. The World Register of Marine species (WoRMS) has been established for a decade. The early history of the database involved compilation of existing global and regional species registers. This aggregation, combined with changes to data types and the changing needs of WoRMS users, has resulted in an evolution of data-entry consistency over time. With the task of aggregating the accepted species names for all marine species approaching completion, our focus has shifted to improving the consistency and quality of data held while keeping pace with the addition of > 2000 new marine species described annually. This paper defines priorities and longer-term aims that promote standardisation within and interoperability among biodiversity databases, provides editors with further information on how to input nomenclatural data in a standardised way and clarifies for users of WoRMS how and why names are represented as they are. We 1) explain the categories of names included; 2) list standard reasons used to explain why a name is considered 'unaccepted' or 'uncertain'; 3) present and explain the more difficult situations encountered; 4) describe categories of sources and notes linked to a taxon; and 5) recommend how type material, type locality and environmental information should be entered.

Climate change is impacting ecosystems globally (Pecl et al., 2017) with increasing temperature and extreme climatic events expected to become more frequent, widespread and persistent through the 21st century (Oliver et al., 2019). In many circumstances, climate change is outpacing the ability of species to adapt, causing mortality, range shifts and new ecosystem states (

Extreme events are increasing globally with devastating ecological consequences, but the impacts on underlying genetic diversity and structure are often cryptic and poorly understood, hindering assessment of adaptive capacity and ecosystem vulnerability to future change. Using very rare "before" data we empirically demonstrate that an extreme marine heatwave caused a significant poleward shift in genetic clusters of kelp forests whereby alleles characteristic of cool water were replaced by those that predominated in warm water across 200 km of coastline. This "genetic tropicalisation" was facilitated by significant mortality of kelp and other co-occurring seaweeds within the footprint of the heatwave that opened space for rapid local proliferation of surviving kelp genotypes or dispersal and recruitment of spores from warmer waters. Genetic diversity declined and inbreeding increased in the newly tropicalised site, but these metrics were relative stable elsewhere within the footprint of the heatwave. Thus, extreme events such as marine heatwaves not only lead to significant mortality and population loss but can also drive significant genetic change in natural populations. Climate change is increasing the intensity and frequency of extreme events 1,2 with significant impacts to species and ecosystems on both evolutionary and contemporary time scales 3. Because extreme events, by definition, exceed normal environmental conditions, they drive significant mortality, range shifts and the transition to novel ecosystem states 4-6. However, in contrast to the ecological impacts of extreme climatic events which are often obvious and well documented, their impact on underlying patterns of genetic diversity and structure and the implications for adaptability to future change is obscure and often unknown 3,7-10 , particularly for marine systems. Marine heatwaves are extreme events defined as discrete periods of anomalously warm-water that exceed historical norms of ocean temperature 11 and are superimposed on a background of ocean warming. Marine heatwaves are increasing in frequency and duration globally 12 with significant consequences for coastal marine species, communities and the ecosystem services they provide 13-17. While we have an emerging understanding of how ocean warming may affect the genetics of marine species e.g. 18,19 , there are few empirical studies demonstrating the genetic impact of extreme marine heatwaves (but see 20,21. One of the most severe marine heatwaves ever recorded impacted ~ 2,000 km of coast off Western Australia in 2011 22 , where sea temperatures soared up to 5.5 °C above normal for several weeks Fig. 1 23,24. The heatwave precipitated widespread and significant local extinction and range contraction of entire marine communities 6,24,25 , shifts in ecological structure 6,26 and impacted fisheries 27 significantly compromising the vast ecosystem goods and services along this coastline 28. Marine forests, comprised of foundation species of kelps and seaweeds that underpin biodiversity throug...