Climate change poses risks to aquaculture, threatening food security

Climate change poses risks to aquaculture, threatening food security

Climate change is a global challenge that has far-reaching consequences for various sectors, including food security. In a recent study published in the journal Microorganisms, scientists have shed light on the impact of global warming on viral infection-related mortality in farmed aquatic animals. The findings highlight the association between rising temperatures and increasing viral pathogenicity, posing risks to aquaculture and ultimately threatening food security.

Background

As the world grapples with the need to maintain food security for a growing population while minimizing the environmental impact of food production, there is a growing interest in exploring sustainable alternatives. One such alternative is aquaculture, which involves the farming of aquatic animals and plants. Aquaculture has emerged as a rapidly expanding sector in food production, playing a vital role in ensuring global food security.

However, the sustainable development of aquaculture is hindered by the rapid emergence and transmission of infectious diseases among farmed aquatic animals, primarily attributed to global warming. In response to this challenge, scientists have conducted a meta-analysis of published studies to investigate the relationship between increased water temperature, resulting from global warming, and the severity of viral infections and related mortality in farmed aquatic animals.

Study Design

The scientists conducted a systematic review of peer-reviewed articles that documented the mortality of farmed aquatic animals due to viral infections. The selection criteria included studies reporting stable specific temperatures for infected aquatic animals. Three viral pathogens, namely Ostreid herpesvirus-1 (OsHV-1), Cyprinid herpesvirus 3 (CyHV-3), and Betanodavirus, were identified for analysis.

Linear regression models were developed to assess the impact of temperature on the mortality of farmed aquatic animals infected by each of these pathogens. The fixed effects considered in the models were temperature, life stage, type of infection, and infection dose. For studies reporting Betanodavirus infections, which involved different fish species and variants of the virus, host and pathogen taxonomy were included as random effects in the models.

Important Observations

The meta-analysis included a total of 53 studies examining the effect of temperature on aquatic animal mortality resulting from viral infections by OsHV-1, CyHV-3, or Betanodavirus. The findings indicate that increased water temperature leads to higher mortality rates in CyHV-3-infected carps, OsHV-1-infected oysters, and Betanodavirus-infected fish.

Among the fixed effects analyzed, temperature emerged as the primary predictor of mortality for OsHV-1-infected oysters. In the case of CyHV-3-infected carps, temperature and type of infection were identified as important predictors of mortality.

Model-Predicted Mortality in Farmed Aquatic Animals

According to the model predictions, a 1 °C increase in water temperature resulted in an induction in mortality of 1.47–8.33% in OsHV-1-infected oysters, 2.55–6.98% in CyHV-3-infected carps, and 2.18–5.37% in Betanodavirus-infected fish. When considering all three types of infections collectively, the models predicted that a 1 °C increase in water temperature is associated with a 3.07–5.70% induction in mortality rates among infected aquatic animals.

Study Significance

The study underscores a positive association between water temperature and viral pathogenicity for OsHV-1, CyHV-3, and Betanodavirus infections. While the findings are specific to these three viruses, they are known to infect a wide range of aquatic animals across diverse habitats in tropical, subtropical, and temperate regions.