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The composition, distribution, origin, and influencing factors of lipophilic marine algal toxins (LMATs) in surface seawater and phytoplankton in Laizhou Bay, China, were comprehensively investigated for the first time. Okadaic acid (OA), pectenotoxin-2 (PTX2), dinophysistoxin-1 (DTX1), dinophysistoxin-2 (DTX2), and pectenotoxin-2 seco acid (PTX2 SA) were discovered in surface seawater, whereas PTX2, OA, 7-epi-PTX-2 SA, DTX1, PTX2 SA, PTX11, and DTX2 were found in phytoplankton in a decreasing concentration order. ∑LMAT concentrations in seawater and phytoplankton were 1.08–35.66 ng/L (mean: 7.31 ng/L) and 0–3609.75 ng/L (mean: 191.38 ng/L), respectively. LMAT contents in seawater and phytoplankton exhibited the highest levels in the southeastern mouth of Laizhou Bay and decreased toward the inner and outer bays. Dinophysis fortii , D. acuminata , D. rotundata , Procentrum lima , and P. minimum were identified as the potential origins of LMATs in Laizhou Bay. Moreover, increased nutrient level and decreased pH in seawater could increase LMAT content. • Lipophilic marine algal toxins in Laizhou Bay were investigated comprehensively. • Various toxins were detected, and okadaic acid and pectenotoxins were the dominant. • High level of toxins was observed in the southeastern mouth of Laizhou Bay. • Dinophysis spp. and Procentrum spp. were identified as the main sources of toxins. • The levels of these toxins will increase under the influence of global change. [ABSTRACT FROM AUTHOR]

Marine algal toxins, highly toxic secondary metabolites, have significant influences on coastal ecosystem health and mariculture safety. The occurrence and environmental control factors of lipophilic marine algal toxins (LMATs) in the surface seawater of the Changjiang estuary (CJE) and the adjacent East China Sea (ECS) were investigated. Pectenotoxin-2 (PTX2), okadaic acid (OA), dinophysistoxin-1(DTX1), and gymnodimine (GYM) were detected in the CJE surface seawater in summer, with concentration ranges of not detected (ND)–105.54 ng/L, ND–13.24 ng/L, ND–5.48 ng/L, and ND–12.95 ng/L, respectively. DTX1 (ND–316.15 ng/L), OA (ND–16.13 ng/L), and PTX2 (ND–4.97 ng/L) were detected in the ECS during spring. LMATs formed a unique low-concentration band in the Changjiang diluted water (CJDW) coverage area in the typical large river estuary. PTX2, OA, and DTX1 in seawater were mainly derived from Dinophysis caudate and Dinophysis rotundata, while GYM was suspected to be from Karenia selliformis. Correlation analyses showed that LMAT levels in seawater were positively correlated with dissolved oxygen and salinity, but negatively correlated with temperature and nutrients, indicating that the hydrological condition and nutritional status of seawater and climatic factors exert significant effects on the distribution of LMATs. [ABSTRACT FROM AUTHOR]