Drivers of dinoflagellate benthic cyst assemblages in the NW Patagonian Fjords System and its adjacent oceanic shelf, with a focus on harmful species

In recent decades, the alteration of coastal food webs (via aquaculture, fishing, and leisure activities), nutrient loading, an expansion monitoring programs have prompted apparent worldwide rise in Harmful Algae Blooms (HABs). Over this time, a parallel increase HABs has also been observed Chilean southern austral region (Patagonia fjords). HAB species like Alexandrium catenella —responsible for Paralytic Shellfish Poisoning (PSP)—are great public concern due to their negative socioeconomic impacts significant northward geographical range expansion. Many toxic dinoflagellate (like A. ) produce benthic resting cysts, yet holistic understanding physical-chemical biological conditions influencing distributions cysts is lacking. study, we measured combination hydrographic (temperature, salinity, dissolved oxygen) sediment properties pH redox potential), addition meiofaunal abundances –as bioturbators potential cyst predators– determine factors distribution, with emphasis on around “hotspot” area Chile. An analysis similarities (ANOSIM) test revealed differences ( p < 0.011) assemblages between fjords oceanic environments. Permutational Analysis Variance (PERMANOVA) showed effects temperature silt proportion explaining assemblages. A generalized linear model (GLM) indicated that temperature, silt/sand, anoxic conditions, low Harpacticoida —a meiofauna herbivore group bioturbator— are associated higher harmful . The implications dynamics discussed, highlighting interactions PSP outbreak initiation. • Significant environments were found. strong association oxygen concentrations. Highest densities found areas lowest oxygenated areas. Biological identified.