Relationships of water age with chlorophyll a concentrations in the eutrophic Lower Alafia River estuary. Michael S. Flannery Xinjian Chen

Transcription

1 Relationships of water age with chlorophyll a concentrations in the eutrophic Lower Alafia River estuary Michael S. Flannery Xinjian Chen

2 Chlorophyll a (µg/l) Kilometers from river mouth

3 KM = (Ln 3-day inflow) r 2 = 0.42, p < Alafia Location of chlorophyll a maxima vs. inflow KM = (1.61 * Season) - (4.31 * Ln Inflow) r 2 = 0.64, p < Peace

4 u g / l Alafia River - Maximum chlorphyll a concentrations vs. inflow Flow (cfs)

5 Dissolved inorganic nitrogen vs. chlorophyll a Lower Alafia River Lower Peace River

6 Alafia River Estuary Particle transport simulations in a 2-D hydrodynamic model

7 Flow Rate = 160 cfs Upstream River Mouth

8 Flow Rate = 40 cfs Upstream River mouth

9 x Simulate times to move 50% of particles past different locations for various rates of inflow = Water Age

10 D a y s Alafia River - Water Age vs. flow at three locations Kilometer 2 Kilometer 6 Kilometer Flow (cfs)

11 Chlorophyll Chlorophyll a (ug/l) 350 Chlorophyll vs. Inflow at Segment 10 Chlorophyll a vs. inflow Kilometer Inflow Inflow (cfs) (cfs)

12 Chlorophyll Chlorophyll a (ug/l) a Chlorophyll vs. Pulse Residence Time at Segment 10 Chlorophyll a vs. water age at Kilometer Pulse Water Residence travel time Time from head from of head estuary of estuary (days) (Days)

13 Chlorophyll Chlorophyll a (ug/l) 250 Chlorophyll vs. a Inflow vs. inflow at Segment Kilometer Inflow Inflow (cfs) (cfs)

14 Chlorophyll Chlorophyll a a (ug/l) 250 Chlorophyll vs. Pulse Residence Time at Segment 2 Chlorophyll a vs. water age at Kilometer Pulse Water Residence travel time Time from from head head of of estuary (days) (Days)

15 Dissolved Inorganic Nitrogen (mg/l) Dissolved inorganic nitrogen vs. water age for river kilometers 2 and Dissolved Inorganic Nitrogen vs Pulse Residence Time for Segments 2 and Seg 2 Seg Pulse Water Residence travel time Time from from head head of estuary of estuary (days) (Days)

16 Median Chlorophyl (ug/l) Median # of Days from Head of Estuary * * * * * * * ** * * ** * * * Labels are km from mouth

17

18 Little Manatee River

19 Little Manatee River

20 D a y s Little Manatee River Water age at kilometer 13 vs. inflow CFS

21 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)

22 Peace River - low flows Mouth River kilometer Fresh

23 Medium Flows Mouth River kilometer Fresh

24 High flows Mouth River kilometer Fresh

25 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)