Structure and dynamics of microbial communities associated with the invasive seaweed Undaria pinnatifida in the Patagonian coast

FERMANI, PAULINA; ZABALA, MARÍA SOLEDAD; GEREA, MARINA; SEGADE, MARIA EUGENIA; GARCIA, PATRICIA; UNREIN, FERNANDO; DIÉGUEZ, MARÍA C.; LOZADA, MARIANA

Buenos Aires

Congreso; ISME-Lat 2023 3rd Latin American Congress of Microbial Ecolog; 2023

International Society of Microbial Ecology ISME

GolfoNuevo, a coastal protected area in a productive and biodiverse marineregion of Patagonia (Argentina), is experiencing ecological andeconomic impacts due to the invasion of the brown alga Undariapinnatifida. Thisstudy evaluates the effect of the exudatesand biomass of U.pinnatifidaon coastal microbial communities under the premise that changes atthis level will affect coastal food webs. Microbial communitiesassociated to surface water and kelp bed water were analyzed in PuntaEste (Golfo Nuevo), a site heavily colonized byU. pinnatifida.Flow cytometry showed that the abundance of heterotrophic bacteria(HB), picocyanobacteria (Pcy) and picoeukaryote (Peuk) were relatedto physico-chemical factors, seasonality and sampling depth, inaccordance with bacterial community structure determined by molecularmethods. In surface waters, nutrient inputs (NO2-+NO3-)favored phytoplankton growth increasing Chl-aconcentrationin winter; while in the algal bed Chl-awas independent of these nutrients. U.pinnatifida biomassfollowed a seasonal pattern, peaking in November (301 ± 170 g m-2dw)and decreasing towards the end of the summer. This decline wascoupled with the increase of fresh dissolved organic carbon, higherNH4+concentrationand abundance peaks of HB and Pcy. Bacterial communities from thealgal bed showed high capability for degrading alginate, a majorcomponent of brown algae cell walls. These results show the structureand dynamics of microbial communities are linked not only to winternutrient inputs typically observed in this region, but also to thesummer nutrient release from the decaying algal biomass, addingto the effects already known of U.pinnatifida.p { margin-bottom: 0.25cm; direction: ltr; color: #000000; line-height: 115%; text-align: left; orphans: 2; widows: 2; background: transparent }p.western { font-family: "Calibri", serif; font-size: 11pt; so-language: es-ES }p.cjk { font-family: "Calibri"; font-size: 11pt; so-language: en-US }p.ctl { font-family: ; font-size: 11pt; so-language: ar-SA }