Aquatic Animal Health in Aquaculture: Disease, Diagnosis, and Holistic Management

Dr. Isabelle Arzul is a research scientist at Ifremer in La Tremblade, France, one of the most important oyster-producing regions in Europe. A veterinarian by training with a PhD on oyster herpesvirus, she has spent over 20 years specializing in shellfish diseases. She led the EU Reference Laboratory for Mollusc Diseases for nearly 15 years and now heads the ASIM team (Adaptation and Health of Marine Invertebrates) at Ifremer, which combines research with diagnosis, surveillance, and training across the European national laboratory network.In this episode, we look at aquatic animal health through the lens of someone operating at the highest level of the field. Isabelle walks us through the role of reference laboratories and why Europe has built a coordinated network of public institutions to harmonize disease surveillance across countries. She explains why disease outbreaks are never just about the pathogen, covering the interplay between the host, environment, and husbandry practices, and how this understanding has led to concrete, practical changes on oyster farms, including a farming calendar that reduced mortality by 30%. We also get into the difference between listed and unlisted diseases, diagnostic methods from histology to PCR, selective breeding for disease resistance, and a fascinating vaccination-like approach that primes oyster immune systems against herpesvirus before exposure. While Isabelle's expertise is in shellfish, the principles translate directly to abalone, sea urchins, and other species being developed across southern Africa.This episode is part of the LIMAQUA Focus Series, produced under the LIMAQUA Programme, a South African-French joint research initiative on nutrition-sensitive marine aquaculture.