Jellyfish Stings Trigger Gill Disorders and Increased Mortality in Farmed Sparus aurata (Linnaeus, 1758) in the Mediterranean Sea

Abstract

Jellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses.

Crude venom from nematocysts of Pelagia noctiluca (Cnidaria: Scyphozoa) elicits a sodium conductance in the plasma membrane of mammalian cells

“…Consequences of Cnidaria stings may range from minor local irritation to severe local and systemic reactions including excruciating pain and life-threatening cardiovascular collapse depending on the Cnidarian species, age of the victim and size of the area contacted. In addition, Cnidarians outbreaks may interfere with human activities such as tourism, bathing, aquatic events, fishing and aquaculture, causing substantial economical burden1234. On the other hand, Cnidarians venom is a rich source of bioactive substances that may have therapeutic potential and other useful applications567.…”

Consequences of Stinging Plankton Blooms on Finfish Mariculture in the Mediterranean Sea

“…Experimental studies with the scyphozoan A. aurita showed gill epithelium recovery required 2 weeks after even brief (10 h) contact between jellyfish and salmonids (Baxter et al, 2011b). Equally, laboratory experiments carried out by Bosch-Belmar et al (2016b), demonstrated partial recovery of sea bream gill tissue after 3 weeks from fish exposure to medium densities of P. noctiluca. These gill disorders used to pass unnoticed, but the consequences of this stressful situation (repeated contact with jellyfish) could be severe, and even if fish gill epithelium could FIGURE 7 | Generalized linear model between total gill score and cnidarian density for the Almería facility (above) and the Málaga fish farm (below).…”

“…Tiny and almost transparent medusae, siphonophores, and hydrozoan larvae may easily remain unnoticed to aquaculture operators, but they can develop high density blooms, be inhaled by fish, and inflict severe damage due to nematocyst discharge and consequent tissues envenomation (Fosså et al, 2003). A range of morphological injuries caused by contacts with cnidarian stinging cells have been described on several cultured fish species (Baxter et al, 2011b;Bosch-Belmar et al, 2016b;Marcos-López et al, 2016). Available evidence shows that a few hours of exposure to stinging cells may lead to severe damage at cellular, tissue and systemic levels, including changes in fish metabolic performances (BoschBelmar et al, 2016a).…”

Concurrent environmental stressors and jellyfish stings impair caged European sea bass (Dicentrarchus labrax) physiological performances

“…were obtained from an aquaculture facility near Licata (Sicily, Italy). The choice of juveniles was related to severe mortality events caused by jellyfish in different Mediterranean aquaculture facilities where the most affected fish class ranged 15–60 g in weight 28 .…”

“…Beyond these few studies, limited information is available on how jellyfish affect fish health, the biological mechanisms underlying fish mortalities, or estimates of potential economic losses 21 . Only a few studies described significant fish injuries caused by the discharge of cnidocytes (specialized cnidarian stinging cells) in fish tissues (skin, gills) leading to envenomation and cellular damage 23 28 .…”