The first phycopathological atlas in Latin America unveils the underdocumentation of algal pathogens

To date, the biodiversity of disease-causing agents in algae has been poorly investigated. This information however is particularly relevant, as outbreaks are repeatedly reported in mariculture facilities or commercial wild stocks, with no available baselines to compare with. Algal pathogens identified in Latin America are few; information is scattered and mostly unknown for regional aquacultural actors such as farmers, seaweed gatherers, conservation biologists and policymakers. In this work, we reviewed all the pathogens described for algae in Latin America, including their taxonomy, macro and microscopic symptoms, aetiology, habitat and reported distribution in this region. Furthermore, we included new records obtained in 2020–2022 in the Southeastern Pacific, and the results of a screen for viruses on kelp gametophytes from a regional germplasm including south Pacific and Atlantic strains. Only nine countries have described algal pathogens so far. The Southeast Pacific (Chilean coast) concentrates the largest number of records and correspond to endophytic algae of different taxa (34 %), viruses (21 %) and protistan pseudofungi (20 %). In our 2020–2022 sampling campaigns, 33 new records were reported for Latin America, which constitutes 15 % of the total records for the region. Overall, unbalanced track records were detected at geographical (e.g. country), temporal (year), diagnosis type and outbreak level, possibly due to scattered and unsystematic sampling efforts. Our results show that pathogens remain cryptic threats for seaweed-related human activities. We anticipate that as the sampling effort increases, algal pathogen records will also increase in number and importance, in proportions comparable to other ecologically and commercially relevant aquatic resources.