Diseases of marine fish and shellfish in an age of rapid climate change

Abstract

A recurring trend in evidence scrutinized over the past few decades is that disease outbreaks will become more frequent, intense, and widespread on land and in water, due to climate change. Pathogens and the diseases they inflict represent a major constraint on seafood production and yield, and by extension, food security. The risk(s) for fish and shellfish from disease is a function of pathogen characteristics, biological species identity, and the ambient environmental conditions. A changing climate can adversely influence the host and environment, while augmenting pathogen characteristics simultaneously, thereby favoring disease outbreaks. Herein, we use a series of case studies covering some of the world's most cultured aquatic species (e.g., salmonids, penaeid shrimp, and oysters), and the pathogens (viral, fungal, bacterial, and parasitic) that afflict them, to illustrate the magnitude of disease-related problems linked to climate change.

Keywords: Aquaculture; Aquaculture diseases; Aquatic science; Environmental science; Global change; Microbiology; Oceanography; Zoology.

Graphical abstract

Figure 1

Global ocean temperature trends Derived from the HadCRUT5 (ensemble means and uncertainties) dataset of Morice et al. (2021) that uses a combination of sea-surface temperatures and near-surface air temperatures over land and compared against the 1961–1990 reference period.

Figure 2

Environmental, host and pathogen/parasite features that co-exist to promote disease outbreaks

Figure 3

Damage to the hepatopancreas (HP) of shrimp infected with V. parahaemolyticus caused by toxins (A) Normal histological structure of the hepatopancreas. (B) Appearance of damaged hepatopancreas. Note tubule disruption.

Figure 4

American lobsters (Homarus americanus) with epizootic shell disease (A) Lobster from Rhode Island with a light infection manifesting as pinprick like lesions on the dorsal carapace. (B) Lobster from Rhode Island, USA with a heavy infection manifesting as coalesced lesions covering >30% of the carapace and limbs. (C) Histological section through the dorsal carapace of a lobster from the Gulf of Maine showing a large “pseudomembrane” (unlabelled arrows) and intensive cellular infiltration (∗) by hemocytes below the affected cuticle (C).

Figure 5

Gross gill appearance—an example of gill disease in Atlantic salmon, Salmo salar