Responses of Microbial Communities to Increases in Nitrogen Loads in - PDF document

Responses of Microbial Communities to Increases in Nitrogen Loads in Salt Marshes Jennifer L. Bowen University of Massachusetts Boston ! Symposium on C/N Cycling and Ecosystem Valuation of Tidal Wetlands in the Northeast Waquoit Bay National Estuarine Research Reserve 24 January 2013 Motivating question: What role does microbial diversity play in the ecosystem services provided by salt marshes ! primary! climate!change! produc+on! 10,000! carbon! shoreline!! 1000! spa+al!scale!(m) ! export! stabiliza+on! eutrophica+on! 100! nutrient! carbon!! food!web! reten+on! 10! sequestra+on! support! 1! denitrifica+on! nursery! grounds! 10 $3! 10 $6! hour ! day ! week ! month ! year ! decade ! century ! � To!scale!from!the!leaf!to!the!ecosystem!to!the!landscape!and!beyond,!we!must!understand! how!informa+on!is!transferred!from!fine!scales!to!broad!scales!and!vice!versa.!!We!must!learn! how!to!aggregate!and!simplify,!retaining!essen+al!informa+on!without!geGng!bogged!down!in! unnecessary!details � !!!$Simon!Levin!(1992)!!

Introduction: the unseen diversity ! !Woese&1987& Introduction: The REALLY unseen diversity (denitrifying microbes) ! !Woese&1987&

Introduction: The 3Rs — essential information or unnecessary detail? ! Resistance! Microbial! no!change!in! Microbial! composi+on! composi+on! composi+on! or!func+on! Resilience! temporarily!altered! return!to!ini+al!!state! composi+on! Redundancy! permanently!altered! no!change!in!func+on! composi+on! change!in!form! and!func+on! !modified&from&Allison&and&Mar6ny&2008& Methods: We can assess the 3 Rs, and whether they matter to ecosystem services, by looking at microbial genetics ! DNRA ! N fixation ! + ! NH 4 N 2 ! N 2 ! - ! NO 2 NO ! N 2 O ! norB& nirS& nosZ& nirK& - ! NO 3 Nitrification ! Denitrification ! amoA& NH 3 ! NH 2 OH ! NO 2 - ! NH 2 OH ! N 2 H 2 ! N 2 ! N4 4 + ! Anammox ! Modified&from&Philippot&et&al.&2007&

Methods: Sippewissett Salt Marsh plots ! Fertilization began in 1971 ! 4 treatments ! 1. CONTROL !! 2. LOW (LF) ! ~ 0.86 g N/m 2 /wk ! 3. HIGH (HF) ! ! ~2.52 g N/m 2 /wk ! 4. XHIGH (FX) ! ~7.56 g N/m 2 /wk !

Methods: deep sequencing of functional gene diversity ! marsh plot nirS mp1 mp2 mp3 800 mp5 mp6 mp7 600 mp8 mp9 TUs 400 O individual clone nirS 200 PA clone SHC2 clone SHCS clone 0 SK clone 0 8000 12000 4000 Sequences --Weisman et al. (In press) ! Results: There is a LOT of unseen diversity, especially in marshes ! No matches within 80% similarity No matches within 80% similarity No matches within 80% similarity 0.1 S c a l i n d u a ( Marinobacter (>90%) > 9 0 % ) Marsh sediments D e c h l o Estuarine sediments r o m o n Eastern Tropical S. Paci fi c OMZ a s ( > 8 5 % Arabian Sea OMZ )

Results: diversity and richness of nirS genes vary tremendously ! Aggregate score 1500 Shannon Chao Arabian Sea 1.89 20 Number of OTUs 1000 ETSP 1.40 18 4.07 238 Chesapeake Bay 500 4.94 862 Sipp. salt marsh 0 0 20000 40000 60000 Number of sequences Results: Some effect of fertilization on denitrifiers ! More similar 12 Count 8 mp2_high 0.88 0.87 0.88 0.89 0.85 0.84 0.85 4 mp6_xhigh 0 0.88 0.77 0.9 0.96 0.96 0.94 0.93 mp8_xhigh 0.87 0.77 0.94 0.96 0.97 0.95 0.9 mp3_cont 0.88 0.9 0.94 0.69 0.8 0.8 0.84 mp1_low 0.89 0.96 0.96 0.69 0.8 0.81 0.82 mp7_cont 0.85 0.96 0.97 0.8 0.8 0.63 0.72 mp5_low 0.84 0.94 0.95 0.8 0.81 0.63 0.59 mp9_high 0.85 0.93 0.9 0.84 0.82 0.72 0.59 mp6_xhigh mp8_xhigh mp2_high mp3_cont mp7_cont mp9_high mp1_low mp5_low

Results: But also a strong elevation effect ! elevation low ��� (cm above MSL) 55 control �� �� �� ��� PC2 (19%) 75 �� ��� xhigh ��� high xhigh control ���� low high ���� ���� ��� ��� ��� PC1 (33%) Introduction: DNF in marine systems accounts for 60% of fixed N loss ! NorB ���� 1_low ��� ��� 53 �� 58 ����������� 8 33 �� ��� �� 37 ��� 7_control ��� 115 ������ ��� ��� 31 ��� ������ �� ������� 9 �� ������������ �� ��� �� ��� 59 ��� �� 19 �� �� �� ��� �� �� 51 ������ 1(LF) 38 ��� ��� �� �� ���� ��� ��� �� ��� ��� �� 57 151 ������� ��� �� ���� �� ���� 5_low ��� 57 �� 3_control �� 59 �� �� �� ������ 97 ������ 7 ������ �� �� �� �� ���� ���� �� �� ������ �� ���� ���� ���� ��� ��� ��� ���� ���� ��� ��� ��� ��� ���

Acknowledgements ! 1. Funding for this research came from: 1. National Science Foundation 1. DEB-0717155 to (JLB, JEH, and HGM) 2. DBI-0400819 (to JLB) 3. DEB-1019624 (to JLB, BBW) 4. Multiple NSF grants to BBW 2. Princeton University Council on Science and Technology (to JLB) 3. UMass Boston Startup Fund (to JLB) Additional thanks: Ivan Valiela, John Teal, Brian Howes, Dale Goehringer and many others at WHOI, MBL and SMAST for initiating and maintaining the Sippewisset. Additional assistance from D. Weisman, and M. Yasuda (UMB), S. Huse, L. Murphy, P. Neal, and C. Holmes (MBL), the lab groups of B. Ward and F. M.M. Morel (Princeton Universityt Fertilization plots as well as the Gifford and Hughes families for access to the plots.