Changes in bacterial activity and community composition in response to water mass mixing

SAME15 – 15 h Symposium on Aqua ic Mic obial Ecology Changes in bac e ial ac i i y and communi y composi ion in esponse o wa e mass mixing Tama a Rod íguez-Ramos (1), Elisa Gue e o-Feijóo (1), Ma Nie o-Cid (2), E a Sin es (3), and Ma a M. Va ela (1) (1) Ins i u o Español de Oceanog a ía (IEO), Cen o Oceanog á ico de A Co uña, Paseo Alcalde F ancisco Vázquez 10, 15001, A Co uña, Spain (2) IIM-CSIC, Ins i u o de In es igacións Ma iñas, Edua do Cabello 6, 36208 Vigo, Spain (3) Depa men o Limnology and Bio-Oceanog aphy, Uni e si y o Vienna. Al hans asse 14 A-1090 Vienna, Aus ia ABSTRACT Mixing zones and bounda ies be ween di e en wa e masses a e “ho spo s” o ma ine biodi e si y and ac i i y. We aimed o in es iga e he e ec s o wa e mass mixing in he da k-ocean mic obial communi ies by collec ing and incuba ing na u al bac e ial communi ies om he Medi e anean Wa e (MW; a 1000 m dep h), he Subpola Modal Wa e (SPMW, 500m) and he Lab ado Sea Wa e (LSW, 1800 m), and compa ing hem wi h a i icially mixed communi ies. Mixing expe imen 1 consis ed o incuba ing a in si u condi ions he o iginal LSW and MW communi ies, plus a mix u e o bo h (MIX1, dilu ion 1:1), whe eas he Mixing expe imen 2 included he o iginal p oka yo ic communi ies om SPMW and MW and a mix u e o bo h (MIX2, dilu ion 1:1). Bac e ial abundance and ac i i y was moni o ed e e y 24h o e 8 days, while bac e ial communi y composi ion and DOM cha ac e iza ion we e assessed a he beginning (day 0), middle (day 4) and a he end o he expe imen (day 8). Li e p oka yo ic cell abundance was highe in he MIX1 and MIX2 ea men s as compa ed o he o iginal communi ies. Mo eo e , MIX1 bac e ia showed sligh ly highe leucine inco po a ion a es han MW o LSW. These me abolic esponses we e accompanied by changes in he op ical p ope ies o DOM, sugges ing a change in he dynamics o he o ganic ma e . Taken oge he , ou esul s indica e di e ences in he bio- eac i i y o he o ganic ma e a e mixing as compa ed o he o iginal wa e masses ha could in luence he composi ion and ac i i y o he bac e ial communi y. Keywo ds: da k-ocean, bac e ial ac i i y, bac e ial di e si y, wa e mass mixing, dissol ed o ganic ma e . SAME15 – 15 h Symposium on Aqua ic Mic obial Ecology Sec ion: 1) Mic obes in u u e aqua ic en i onmen s (Response o aqua ic mic obial communi ies o en i onmen al changes) Type o p esen a ion: O al