The boom of commercial macroalgae in Europe in the last ten years has been constantly expanding. In general in the world, the attention on macroalgae, especially as food, has increased with the awareness of a person’s good health; for example in Korea in 2020 there was an increase in the consumption of nori equal to 60%. Several species are exploited for food and dietary supplements, animal feed, chemicals, and much more. The volume of the biomass cultivated for commercial purpose is fast-growing, also through integrated multi trophic aquaculture (IMTA). Considering economical and social benefit, the farms have to face the emergence of algal diseases. It is a situation not to be underestimated indeed, the control and prevention of diseases is estimated at about 35% of total costs. The infectious disease in algae involves a transmissible infectious agent (bacteria, fungi, virus, etc.) while the non-infectious is induced by physiogenic factors such as extremes of temperature, salinity, light intensity or pollution; for example “blisters disease” in Laminaria spp. (Fig. 2). In macroalgae the concept of pathogen-disease is not always appropriate, because frequently is the synergy of both (infectious and non-infectious factors) to reach the state of pathology. It is therefore important to clarify all the different kinds of pathologies and, were possible, prevent and treat the diseases, also in accordance with the new economic policies and European directives. Some diseases are better characterized than others and this is because some cultivation systems are better established than others. For example, considering “nori”, there are more than ten different known diseases that affect Porphyra/Pyropia farming: oomycetes (Fig. 1), such as species of the genera Pythium and Olpidiopsis, known as “red rot disease” and “Olpidiopsis disease”, respectively, or the Pyro V1 virus responsible of “green-spot disease”. In the Gigartinales order, Eucheuma spp. and Kappaphycus spp., it is very common to diagnose the “ice-ice” disease, which is a “pathology” defined as a symptom and has recently been treated as such. For these carragenophytes, another important problem is the “goose bump” disease, an infestation caused by an endophytic filamentous alga (EFA), mainly of the genus Neosiphonia. The infestation of EFA is a serious trouble of farmed Saccharina, often caused by species of Laminariocolax and Laminarionema. Symptoms are often caused by synergy of different pathologies and their identification can be difficult or misleading. In this regard, the use of molecular analyses could be very useful to achieve an accurate identification and, therefore, for testing suitable treatment. It is noteworthy that some pathogens can carry out a “cross-species transmission” often resulting in symptoms which are more severe and more incisive in the new host than in the previous one. Examples are the EFAs from Sargassum infecting Kappaphycus and species of the genus Pythium from Porphyra that could infect Ulva spp. Macroalgal pathologies are often an underestimated and undervalued field. However, in the near future, due to the growing increase in algal farms, it will be necessary to outline appropriate protocols to quickly achieve a correct identification of the pathologies and to apply an adequate treatment to the algae.

Pathologies of macroalgae: risk to take into a new farm management vision

Damiano Spagnuolo
Primo
;
Antonio Manghisi
Secondo
;
Marina Morabito;Giuseppa Genovese
Ultimo
2021

Abstract

The boom of commercial macroalgae in Europe in the last ten years has been constantly expanding. In general in the world, the attention on macroalgae, especially as food, has increased with the awareness of a person’s good health; for example in Korea in 2020 there was an increase in the consumption of nori equal to 60%. Several species are exploited for food and dietary supplements, animal feed, chemicals, and much more. The volume of the biomass cultivated for commercial purpose is fast-growing, also through integrated multi trophic aquaculture (IMTA). Considering economical and social benefit, the farms have to face the emergence of algal diseases. It is a situation not to be underestimated indeed, the control and prevention of diseases is estimated at about 35% of total costs. The infectious disease in algae involves a transmissible infectious agent (bacteria, fungi, virus, etc.) while the non-infectious is induced by physiogenic factors such as extremes of temperature, salinity, light intensity or pollution; for example “blisters disease” in Laminaria spp. (Fig. 2). In macroalgae the concept of pathogen-disease is not always appropriate, because frequently is the synergy of both (infectious and non-infectious factors) to reach the state of pathology. It is therefore important to clarify all the different kinds of pathologies and, were possible, prevent and treat the diseases, also in accordance with the new economic policies and European directives. Some diseases are better characterized than others and this is because some cultivation systems are better established than others. For example, considering “nori”, there are more than ten different known diseases that affect Porphyra/Pyropia farming: oomycetes (Fig. 1), such as species of the genera Pythium and Olpidiopsis, known as “red rot disease” and “Olpidiopsis disease”, respectively, or the Pyro V1 virus responsible of “green-spot disease”. In the Gigartinales order, Eucheuma spp. and Kappaphycus spp., it is very common to diagnose the “ice-ice” disease, which is a “pathology” defined as a symptom and has recently been treated as such. For these carragenophytes, another important problem is the “goose bump” disease, an infestation caused by an endophytic filamentous alga (EFA), mainly of the genus Neosiphonia. The infestation of EFA is a serious trouble of farmed Saccharina, often caused by species of Laminariocolax and Laminarionema. Symptoms are often caused by synergy of different pathologies and their identification can be difficult or misleading. In this regard, the use of molecular analyses could be very useful to achieve an accurate identification and, therefore, for testing suitable treatment. It is noteworthy that some pathogens can carry out a “cross-species transmission” often resulting in symptoms which are more severe and more incisive in the new host than in the previous one. Examples are the EFAs from Sargassum infecting Kappaphycus and species of the genus Pythium from Porphyra that could infect Ulva spp. Macroalgal pathologies are often an underestimated and undervalued field. However, in the near future, due to the growing increase in algal farms, it will be necessary to outline appropriate protocols to quickly achieve a correct identification of the pathologies and to apply an adequate treatment to the algae.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3209250
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