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Effect of phosphorus enrichment Effect of phosphorus enrichment

• n periphyton structure,
• n periphyton structure,

composition, and metabolism composition, and metabolism

Jay W. Munyon and Evelyn E. Gaiser Florida International University

Everglades Periphyton

• Benthic calcareous mats, floating mats, and epiphytic

periphyton

• Everglades periphyton varies spatially:

– Nutrients, light, substrate, water depth

• Long term data has shown changes in biomass in response to

changes in water phosphorus levels

25 50 75 100 10 100 1000 10000

Periphyton Cover (%)

2000 4000 6000 8000 10000 10 100 1000 10000

Periphyton Biovolume (ml m-2)

200 400 600 10 100 1000 10000

Periphyton AFDM (g m-2) Dry 2005 Wet 2005 Dry 2006 Wet 2006 Season Periphyton Total Phosphorus (µg g-1) Periphyton Total Phosphorus (µg g-1) Periphyton Total Phosphorus (µg g-1) Day 180 Day 1 30 ppb Treatment Day 180 Day 1 30 ppb Treatment

Gaiser et al. 2006 L&O

Periphyton Matrix

Blue greens with filaments of EPS (courtesy M. Gantar) CaCO3 crystals in periphyton mat (courtesy M. Gantar) Diatoms leaving EPS trail on Utricularia purpurea EPS in periphyton mat Encyonema with sheath/trail of EPS

Hypotheses

• As water TP increases:

– System metabolism will change – EPS concentration will decrease – Abundance of mat-forming species will decrease – Periphyton biomass will decrease

Microcosm Experimental Setup

Methods

• Treatments

– Control

Periphyton with filtered Everglades water

– +P

Periphyton with P-enriched filtered Everglades water

– +A

Periphyton pre-incubated in antimicrobial solution and filtered Everglades water

– +P+A

Periphyton pre-incubated in antimicrobial solution and P-enriched filtered Everglades water

• +P = added ~2 µM (30ppb) P using

Na2HPO4

• +A = 250 mg D-cycloserine, 10 mg

ampicillin, 10 mg tetracycline, 100 mg benomyl brought to 1 L with DI H2O

Methods

Methods

• System was run for 7 days
• Analyses

– Metabolism – Extracellular Polysaccharide concentration (EPS) – Diatom abundances – Dry Weight – AFDM – Chl a – Water column TOC, TN, TP – Tissue C, N, P – Soft algae abundances – Bacteria

Methods

• System was run for 7 days
• Analyses

– Metabolism – Extracellular Polysaccharide concentration (EPS) – Diatom abundances – Dry Weight – AFDM – Chl a – Water column TOC, TN, TP – Tissue C, N, P – Soft algae abundances – Bacteria

Effect of Treatment on Respiration

• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 30 35 40 45 50 55 Water TP (ug/L) Respiration (mg O2/g dry/day) Control +P +A +P+A

Hypothesis 1: System metabolism will change with increases in water TP

Respiration rates increased with increasing water TP +A respiration rates differed significantly from control rates

Hypothesis 2: EPS concentration will decrease with increasing water TP

Effect of Treatment on Extracellular Polysaccharide Concentration

10 20 30 40 50 60 70 80 C +P +A +P+A Treatment EPS (ug/g dry)

P enrichment significantly increased EPS concentration +A and +P+A showed no significant change

*

Hypothesis 3: Abundance of mat forming diatoms will decrease

• There were

chamber effects as shown by the before run controls grouping

• ut from the rest.
• After running an

indicator species analysis, we find that Nitzschia amphibia was an indicator P- enrichment

Diatom Relative Abundance NMDS

Axis 1 Axis 2

Treatment Before Control Before +A Control Control +P+A +P +A

Hypothesis 4: Periphyton biomass would decrease with increasing water TP

Effect of Treatment on Periphyton Biomass 0.5 1 1.5 2 2.5 3 Control +P +A +P+A Treatment Dry weight per chamber (g)

Periphyton biomass decreased significantly with increased P +A and +P+A showed no significant changes

*

Conclusions

• As water TP increases:

– Metabolism changed with increasing water TP – EPS concentration did not decrease in response to P- enrichment – Nitzschia amphibia abundance did increase as a result of enrichment, however running the experiment for longer may have elicited a stronger response – Periphyton biomass did decrease in response to phosphorus, however this decrease was ameliorated by addition of antimicrobials

Future Directions

• More microcosm research needs to be

performed with greater number of replicates for each treatment

• Periphyton mats need to be collected from

areas with known low phosphorus levels

• We need to find a method to quantify

bacteria in Everglades periphyton mat

Acknowledgements

• Everglades National Park
• Everglades Foundation Fellowship
• SERC Christina Menendez Fellowship
• FCE-LTER
• Committee – Evelyn Gaiser, Joe Boyer, and

Steve Oberbauer

• Miro Gantar
• The Periphyton Group
• The countless people who helped me with this

project

Hypothesis 1: System metabolism will change with increases in water TP

Effect of Treatment on Gross Primary Production

• 0.5
• 0.4
• 0.3
• 0.2
• 0.1

0.1 0.2 0.3 0.4 30 35 40 45 50 55 Water TP (ug/L) GPP (mg O2/g dry/day) Control +P +A +P+A

Water column TP of controls did not differ significantly from +P Control GPP did not differ significantly from +P +A had lower TP than control indicating uptake from water column +P+A had lower TP than +P indicating that antimicrobials treatment increased P uptake GPP increased significantly with increasing TP

Effect of Treatment on Net Ecosystem Production

• 0.1
• 0.08
• 0.06
• 0.04
• 0.02

0.02 0.04 0.06 0.08 30 35 40 45 50 55 Water TP (ug/L) NEP (mg O2/g dry/day) Control +P +A +P+A

NEP increased with increasing water TP +A and +P NEP did not differ significantly from control NEP

Hypothesis 1: System metabolism will change with increases in water TP