Macroalgae as an Indicator of Estuarine Condition

Eric Milbrandt, Ph.D.

Marine LaboratorySanibel-Captiva Conservation Foundation (SCCF)

Caloosahatchee Science Workshop 2013Florida Gulf Coast University

11/20/13

Background

• “Unattached” macroalgae is a common component of seagrass communities– Provides food and refuge for

seagrass fauna (Virnstein and Carbonara 1985, Fry 1984)

– Has high levels of productivity (Williams 1977)

– Contributes to the DOC pool through decomposition (Zieman 1984)

– High levels of nutrition, little refractory carbon (Hermann 1994)

– Extensive drift algal abundances decrease the amount of available light in seagrass (William Cowper 1978, Montfrans 1984)

– Drift algal blooms decrease seagrass vertical shoot density in the presence of urchins (Macia 1999)

4/27/10, trawls in San Carlos Bay

12/6/10, near causeway

Occurrences of “Drift Algae”

• Large accumulations after storms (Williams Cowper 1978) in Biscayne Bay (Josselyn 1977)

• “Tumbling” in sparse seagrass in the IRL (Virnstein 1985), up to 0.5 km/day (Holmquest 1994)

10/19/13 Knapp’s Point after TS Karen

• Initially attached to substrata such as seagrass shells rocks or sponges and breaks loose

• Usually non-calcified fleshy or filamentous, reproduce vegetatively (Norton & Matheison 1983)

12/15/12 Sanibel Lighthouse

Previous studies in FLLocation No. of

Species

Groups Dominant Species Mean Biomass

Ft. Pierce (Benz et al.

1979)

63 3 blue-green12 green9 brown39 red

Acanthophora spiciferaChondria tenuissimaDictyota dichotoma

Hypnea spp.Spyridia filamentosaGiffordia mitchelliae

Gracilaria spp.Rosenvingea intricate

1.8-8.7 g dry wt m-2

Anclote estuary

(Hamm and Humm 1976)

65 5 blue-green15 green13 brown

32 red

Laurencia obtusaL.Poteaui

Digenia simplexSargassum spp.

240 g dry wt m-2

Mid-Indian River Lagoon (Virnstein and

Carbonara 1985)

- - Gracilaria spp.Spyridia filamentosa

Jania adhaerensRosenvingea intricata

Acanthophora spiciferaLaurencia spp.

Cladophora proliferaHypnea spp.

Dictyota dichtoma

0.03-164 g dry wt m-2

San Carlos Bay/Gulf of

Mexico (Milbrandt

2010)

96 1 blue-green12 green20 brown

63 red

This presentation 0.01-224 g dry wt m-2

Drivers• Eutrophication-Algal biomass linked to N-

loading– Waquoit Bay Massachusetts, Gracilaria

tikvahae (Valiela 1992)– Bermuda, Caulerpa prolifera (Lapointe

1989)– French Mediterranian coast, Ulva lactuca

(Maze et al 1993)– Sanibel Island, Hypnea, Soleria Dawes

(2003)

Caloosahatchee versus other estuaries

200

800

Biomass g DW m-2

Dixon 2008 TN = 1,873 MT (1,873 X 103 kg) yr-1 Caloosahatchee

Biomass 100-200 g m-2 not uncommonWhat is the tipping point?

Valiela (1997)

Fragmentation

Hypnea fragment survival data support the proliferation that was observed in late 2006, early 2007

Sanibel;02/21/07

(Vermeij et al. 2009)

• Significant differences in species composition and abundance at inshore vs. offshore locations

Common Species

May-08 Jul-08 Sep-08 Nov-08 Jan-09 Mar-09 May-09 Jul-09 Sep-09 Nov-09 Jan-10 Mar-10 May-10 Jul-10

Flo

w (

cfs

) 7 D

ay

Runnin

g A

vera

ge

0

2000

4000

6000

14000

16000

S79 DischargeS77 Discharge

05/08 07/08 09/08 11/08 01/09 03/09 05/09 07/09 09/09 11/09 01/10 03/10 05/10 07/10

Bio

mas

s (g

DW

m-2

)

0.000

0.005

0.010

0.015

0.020

0.025

Champia parvula

05/08 07/08 09/08 11/08 01/09 03/09 05/09 07/09 09/09 11/09 01/10 03/10 05/10 07/10

Bio

mas

s (g

DW

m-2

)

0.00.20.40.60.81.01.21.41.6

Sargassum spp.

May-08 Jul-08 Sep-08 Nov-08 Jan-09 Mar-09 May-09 Jul-09 Sep-09 Nov-09 Jan-10 Mar-10 May-10 Jul-10

Flo

w (

cfs)

7 D

ay R

unnin

g A

ver

age

0

2000

4000

6000

14000

16000

S79 DischargeS77 Discharge

05/08 07/08 09/08 11/08 01/09 03/09 05/09 07/09 09/09 11/09 01/10 03/10 05/10 07/10

Biom

ass (g DW

m-2

)

0.0

0.2

0.4

0.6

0.8

Agardhiella subulata

05/08 07/08 09/08 11/08 01/09 03/09 05/09 07/09 09/09 11/09 01/10 03/10 05/10 07/10

Biom

ass (g DW

m-2

)

0.00.51.01.52.02.53.03.5

Botryocladia occidentalis

INSHORE OFFSHORE

S-79 Flow

0 1000 2000 3000 4000 5000 6000 7000

Bio

ma

ss (g DW

m-2

)

0

50

100

150

200

250

300

350

INSHORE

S-79 Flow (30-day average)

0 1000 2000 3000 4000 5000 6000 7000B

iomass (g D

W m

-2)

0

100

200

300

400

500

600

700

OFFSHORE

2008-2010. Each point represents the mean biomass (n=20) Inshore CES11, near Fishermans Key; offshore is GOM12, 5 miles west of Redfish pass.

15

20

25

30

35

40

Sal

init

y (P

SU

)

NWR01

NWR02

NWR03

NWR04

NWR05

NWR06

NWR07

NWR08

NWR09

NWR10

0

0.3

0.6

0.9

1.2

1.5

1.8

TN

(m

g/l

)

NWR01 NWR02

NWR03 NWR04

NWR05 NWR06

NWR07 NWR08

NWR09 NWR10

90th Percentile All Florida Estuaries 1.2 mg/l

50th Percentile All Florida Estuaries 0.7 mg/l

5

10

15

20

25

30

35

40

Tem

per

atu

re (

oC

)

NWR01 NWR02

NWR03 NWR04

NWR05 NWR06

NWR07 NWR08

NWR09 NWR10

Aldridge and Trimmer (2005) Half saturation constants for green macroalgae (NO3) 0.3 mg/L N. In: Anderson and Conley (2005)

Ambrose EPA WASP models use 0.1 mg/L N half saturation for macroalgal external N uptake.

Sufficient nutrients in the lower Caloosahatchee Estuary to support year round macroalagal growth.

Driver-Irradiance• Higher irradiances inshore from Dec. to May after N-

loading.• Offshore, high irradiances coincident with flows and

loading

(SCCF, Ladyfinger Lakes 4/1/13)

Driver-herbivory• Lack of inshore

urchins?

Top Down Control• Evidence from panhandle that grazer abundance can

control macroalgal proliferations (Heck and Valentine)• Results from one offshore location with abundant grazers

suggests some top down control at GOM04 (Coen et al. 2010) but low salinities prevent larval settlement in San Carlos Bay

Driver-Roughness• Benthic habitat maps

(G. Foster 2010)

Driver-Temperature• Temperature had a significant affect on

photosynthesis and daily growth, salinity did not (Brown, USF M.S. thesis 2001)– Temperatures can be several degrees warmer in shallow sites

(SCCF RECON data), growth rates from the field are needed.

• Biomass and percent cover (Scanlan 2009 framework), N-loading, residence time vs. growth rates

• Inshore and offshore locations needed to capture large (extreme) interannual differences in S79 flows

• Improve CHNEP mapping by determining accuracy of SAV maps (patchy/continuous, with/without macroalgae)

• Improves SAV indicators by providing additional drivers (space competition) and ecosystem services

• Improves beach condition indicators (red tide, bacteria)

• Methods and equipment proven and tested in the 2010 study

Indicator Considerations

SCCF Current efforts• Growth and N uptake rates (ammonia, NOX, TN) of

local species• Measure growth rates (or mortality rates) of beach

collected drift algae• Quantify biomass and percent cover from a 4 shore-

side locations• Develop a key to common species in SW Florida • Workshop with FDEP and others to teach the use of

the keys to identify to macroalgae to Genus and improve transect monitoring

Growth Rates – field incubations

Date Species Volume Wet Weight Date Volume Wet Weight10-23-

13 Halymenia floresia 19 mL 14.91 g 11/6/13 17.6 mL 20.81 g10-23-

13 Agardhiela subulata 16.8 mL 14.19 g 11/6/13 26 mL 23.24 g10-24-

13 Agardhiela subulata 40 mL 37.46 g 11/6/13 62 mL 62.73 g10-24-

13 Codium taylorii 102 mL 102.14 g 11/6/13 131 mL 135.35 g10-24-

13 Solieria filiformis 1.8 mL 1.13 g 11/6/13 2 mL 1.29 g10-24-

13 Gracilaria tikvahiae 12 mL 12.79 g 11/6/13 12.1 mL 11.95 g10-24-

13Botrycladia occidentalis 46 mL 46.67 g 11/6/13 71 mL 76.63 g

Acknowledgements

Drs. Loh, Parsons, Everham, A.J. Martignette, Jeff Siwicke, Brad Klement, Keleigh Provost, Mark Thompson, Drs. Greg Foster, Ray Grizzle

Funding Partners:James Evans, City of SanibelSteve Boutelle, Lee County, WCINDRob Loflin, City of SanibelMike Campbell, Lee County