Relationships of water age with chlorophyll a concentrations in the eutrophic Lower Alafia River estuary Michael S. Flannery Xinjian Chen
Chlorophyll a (µg/l) Kilometers from river mouth
KM = 16.47-1.96(Ln 3-day inflow) r 2 = 0.42, p < 0.001 Alafia Location of chlorophyll a maxima vs. inflow KM = 45.20 + (1.61 * Season) - (4.31 * Ln Inflow) r 2 = 0.64, p < 0.001 Peace
u g / l 500 450 400 350 300 250 200 150 100 50 0 Alafia River - Maximum chlorphyll a concentrations vs. inflow 0 200 400 600 800 1000 1200 1400 Flow (cfs)
Dissolved inorganic nitrogen vs. chlorophyll a Lower Alafia River Lower Peace River
Alafia River Estuary Particle transport simulations in a 2-D hydrodynamic model
Flow Rate = 160 cfs Upstream River Mouth
Flow Rate = 40 cfs Upstream River mouth
x Simulate times to move 50% of particles past different locations for various rates of inflow = Water Age
D a y s 12 10 8 6 4 2 0 Alafia River - Water Age vs. flow at three locations Kilometer 2 Kilometer 6 Kilometer 14 0 200 400 600 800 1000 1200 1400 Flow (cfs)
Chlorophyll Chlorophyll a (ug/l) 350 Chlorophyll vs. Inflow at Segment 10 Chlorophyll a vs. inflow Kilometer 10 300 250 200 150 100 50 0 0 100 200 300 400 500 600 700 800 900 1000 Inflow Inflow (cfs) (cfs)
Chlorophyll Chlorophyll a (ug/l) a Chlorophyll vs. Pulse Residence Time at Segment 10 Chlorophyll a vs. water age at Kilometer 10 400 350 300 250 200 150 100 50 0 0 1 2 3 4 5 6 Pulse Water Residence travel time Time from head from of head estuary of estuary (days) (Days)
Chlorophyll Chlorophyll a (ug/l) 250 Chlorophyll vs. a Inflow vs. inflow at Segment Kilometer 2 2 200 150 100 50 0 0 100 200 300 400 500 600 700 800 900 1000 Inflow Inflow (cfs) (cfs)
Chlorophyll Chlorophyll a a (ug/l) 250 Chlorophyll vs. Pulse Residence Time at Segment 2 Chlorophyll a vs. water age at Kilometer 2 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 Pulse Water Residence travel time Time from from head head of of estuary (days) (Days)
Dissolved Inorganic Nitrogen (mg/l) 3 2.5 2 Dissolved inorganic nitrogen vs. water age for river kilometers 2 and 10 16 Dissolved Inorganic Nitrogen vs Pulse Residence Time for Segments 2 and 10-16 Seg 2 Seg 10-16 1.5 1 0.5 0 0 1 2 3 4 5 6 7 8 9 10 Pulse Water Residence travel time Time from from head head of estuary of estuary (days) (Days)
Median Chlorophyl (ug/l) 30 20 10 15 18 0 0 1 2 3 4 Median # of Days from Head of Estuary * * * * * * * ** * * ** * * * Labels are km from mouth 16 14 17 10 9 11 12 13 5 7 8 6 4 32
Little Manatee River
Little Manatee River
D a y s 35 30 25 20 15 10 5 0 Little Manatee River Water age at kilometer 13 vs. inflow 0 100 200 300 400 500 600 700 CFS
Summary In addition to nutrient loading, physical factors related to inflow rate (color, light, residence time including water age) strongly affect phytoplankton biomass Interaction of the volume of freshwater inflow with the morphology of the estuary affects the location of zones of high phytoplankton biomass In some regions of the river, high phytoplankton biomass does not correspond to high nutrient loading due to short residence times. High flows transport areas of high phytoplankton biomass downstream to broader regions where residence time is longer Reductions in flows can result in the upstream movement of zones of high phytoplankton biomass into smaller regions of the estuary, with implications for water quality and overall ecosystem productivity (i.e. fisheries)
Peace River - low flows Mouth River kilometer Fresh
Medium Flows Mouth River kilometer Fresh
High flows Mouth River kilometer Fresh
Summary In addition to nutrient loading, physical factors related to inflow rate (color, light, residence time including water age) strongly affect phytoplankton biomass Interaction of the volume of freshwater inflow with the morphology of the estuary affects the location of zones of high phytoplankton biomass In some regions of the river, high phytoplankton biomass does not correspond to high nutrient loading due to short residence times. High flows transport areas of high phytoplankton biomass downstream to broader regions where residence time is longer Reductions in flows can result in the upstream movement of zones of high phytoplankton biomass into smaller regions of the estuary, with implications for water quality and overall ecosystem productivity (i.e. fisheries)