Occurrence and Trophodynamics of Marine Lipophilic Phycotoxins in a Subtropical Marine Food Web

Abstract

Marine lipophilic phycotoxins (MLPs) are produced by toxigenic microalgae and cause foodborne illnesses. However, there is little information on the trophic transfer potential of MLPs in marine food webs. In this study, various food web components including 17 species of mollusks, crustaceans, and fishes were collected for an analysis of 17 representative MLPs, including azaspiracids (AZAs), brevetoxins (BTXs), gymnodimine (GYM), spirolides (SPXs), okadaic acid (OA), dinophysistoxins (DTXs), pectenotoxins (PTXs), yessotoxins (YTXs), and ciguatoxins (CTXs). Among the 17 target MLPs, 12, namely, AZAs1–3, BTX3, GYM, SPX1, OA, DTXs1–2, PTX2, YTX, and the YTX derivative homoYTX, were detected, and the total MLP concentrations ranged from 0.316 to 20.3 ng g–1 wet weight (ww). The mean total MLP concentrations generally decreased as follows: mollusks (8.54 ng g–1, ww) > crustaceans (1.38 ng g–1, ww) > fishes (0.914 ng g–1, ww). OA, DTXs, and YTXs were the predominant MLPs accumulated in the studied biota. Trophic dilution of the total MLPs was observed with a trophic magnification factor of 0.109. The studied MLPs might not pose health risks to residents who consume contaminated seafood; however, their potential risks to the ecosystem can be a cause for concern.

The Prevalence of Marine Lipophilic Phycotoxins Causes Potential Risks in a Tropical Small Island Developing State

“…The correlation results strongly suggest that using fish body size or trophic position as a threshold to indicate the associated risk and prevent human consumption of contaminated fish is not a practical approach for policymakers to manage risks associated with MLPs. Many studies have reported no or weak correlations between MLPs or an individual MLP, and body size, trophic level, or lipid content in studied fish of Hong Kong, Hawaii, Kiribati, the Caribbean, Okinawa, and French Polynesia. ,,− These results indicated that the accumulation of MLPs may involve a mixture of factors beyond the body size, lipid content, and trophic level. Abiotic factors (e.g., temperature, current, and turbidity) and other biotic factors (e.g., age, feeding preference, and the ability for toxin uptake and depuration) may influence MLP accumulation. ,, However, several studies have found strong correlations between body size or lipid content and toxin levels in certain species.…”

“…Moray eels are more likely to accumulate MLPs due to their top predator position in the food chain and low elimination efficiency (a half-life of over 264 days for CTXs). , They have been considered high-risk species for ciguatera food poisoning in Kiribati, Japan, Vietnam, Canary Islands, and New Caledonia. ,,− Snapper and grouper are also sedentary and high-order carnivores, with epibenthic behavior and strong site fidelity . It was reported that most MLPs tend to accumulate in benthic communities, which is consistent with our study of high MLP levels in snapper and grouper . Soldierfish Myripristis berndti and Myripristis hexagona, which mainly feed on plankton, such as crab larvae, have detected certain levels of MLPs (Table S5).…”

“…71 It was reported that most MLPs tend to accumulate in benthic communities, which is consistent with our study of high MLP levels in snapper and grouper. 21 Soldierfish Myripristis berndti and Myripristis hexagona, which mainly feed on plankton, such as crab larvae, have detected certain levels of MLPs (Table S5). Previous studies have reported Myripristis spp.…”

“…8,20 The regulatory limit for these toxin groups proposed by the European Food Safety Authority (EFSA) is set as 160 ng AZA equiv/g, 160 ng OA equiv/g, 3750 ng YTX equiv/g shellfish meat, and 0.01 ng P-CTX-1 equiv/g fish meat, but the regulatory limit for GYM, SPXs, and BTXs are unavailable. 21 MLPs are transferred to higher trophic levels of the food web by predation, and thus the accumulation of MLPs is influenced by the feeding habits and habitat preferences of marine organisms. 22 Moreover, some marine organisms can metabolize the toxin into less toxic compounds, while others may increase its toxicity.…”

“…), and marine mammals (shark, whales, and seals, etc. ). − The presence of MLPs in seafood will lead to poisoning incidents and even fatalities, as evidenced by numerous reported cases of MLP-related poisonings worldwide. − Typical MLPs include azaspiracids (AZAs), brevetoxins (BTXs), gymnodimine (GYM), spirolides (SPXs), okadaic acid (OA), dinophysistoxins (DTXs), pectenotoxins (PTXs), yessotoxins (YTXs), and ciguatoxins (CTXs). , The regulatory limit for these toxin groups proposed by the European Food Safety Authority (EFSA) is set as 160 ng AZA equiv/g, 160 ng OA equiv/g, 3750 ng YTX equiv/g shellfish meat, and 0.01 ng P-CTX-1 equiv/g fish meat, but the regulatory limit for GYM, SPXs, and BTXs are unavailable …”