Cody Eggenberger, Florida International University Research Mentor: Dr. Jennifer Rehage

Coupling telemetry and stable isotope techniques to unravel movement: Common Snook habitat use across variable nutrient environments

Goals ResultsResearch Methodology

This material is based upon work supported by the National Science Foundationunder Grant No. HRD-1547798. This NSF Grant was awarded to FloridaInternational University as part of the Centers of Research Excellence in Scienceand Technology (CREST) Program. Any opinions, findings, and conclusions orrecommendations expressed in this material are those of the author(s) and donot necessarily reflect the views of the National Science Foundation.

cegge004@fiu.edu

http://crestcache.fiu.edu

• Determine if Common Snook (Centropomusundecimalis) habitat use differs within two neighboring, yet distinct estuaries.

• Add to the creation of a predictive framework for the impacts hydrologic variation, restoration, and climate change have on recreational sportfish in the coastal Everglades.

• Eutrophication via effects on resource production can influence consumer movements.

• Snook moved more in the less enriched system.• Snook relied on a greater diversity of basal resources in the more

enriched system.• Coupling movement and trophic ecology can be a powerful

approach.

The Alligator Creek subestuary (ACS) and McCormick Creek subestuary (MCS) are two neighboring, yet distinct lake systems located in northcentral Florida Bay within Everglades National Park. The ACS has been more impacted from reductions in freshwater inflows to the Everglades than the MCS. This makes the two subestuaries ideal natural environments for comparing how varying abiotic conditions may be impacting recreational sportfish habitat use.

AC System MC System

Nutrient Levels

Connectivity w/ FL Bay

Salinity

Freshwater Inflow

System Mean TN (μM)

Mean TP (μM) Chl α (μg/L)

ACS 81-105 1.82-2.86 11.3-31.5

WLS 51-57 0.67-0.83 2.6-3.8

Concentration ranges measured from June 2016 to May 2017

Lake

4 3 2 1

Receiver

Movement Metrics

Example calculation of movement metrics for a fish with the following detection history.

The Coastal Everglades Acoustic Receiver Array (CELA2) consists of 48 receivers and tracked the movements of 25 Snook (8 in ACS and 17 in MCS) from June 1, 2016 to May 31, 2017.

Sampling Protocol1. Creation of acoustic

array (CELA2).2. Catch Snook and take

fin clips for stable isotope analysis

3. Surgically implant Snook with acoustic transmitters.

4. Revive and release tagged Snook.

5. Download acoustic array every 4 months.

1.

3.

4.

2.

Focal fish species- Common Snook (Centropomus undecimalis)

p

Date

06/16 07/16

08/16 09/16

10/16 11/16

12/16 01/17

02/17 03/17

04/17 05/17

06/17 07/17

08/17

Sta

ge (

cm)

-50

-40

-30

-20

-10

0

10

20

30

Zo

ne

s

1

2

3

4

5

6

Stage (cm) Fish Detections

Snook 53345

Movement track of acoustically tagged Snook, 53345, in MCS with stage data.

Movement metrics for Snook across systems and zones within systems a) movement events by systemb) residence time by systemc) movement events by zone and

systemd) residence times by zone Snook had higher movement events in the mesotrophic system, but similar residence time, except for an overall trend for shorter residence times in downstream zones. Snook movements were particularly high in the upstream and middle zones of the mesotrophic system.

a) Boxplots of the source contributions to Snook determined by MixSIAR. Snook in the enriched system have more diverse source contributions than those in the mesotrophic system. Bars = mean, boxes = standard deviation, whiskers = 95th and 5th percentiles. Abbreviations for basal resources: Hal = Halodule, Rup= Ruppia, Cha = Chara, Thal= Thalassia, POM = particulate organic matter, and BMA = benthic macroalgae.

b) Boxplots of the trophic levels of Snook in the eutrophic and mesotrophic systems determined by MixSIAR. Results show no trophic level difference between Snook in the two systems.

Positive relationship between residence time and trophic level for all Snook tracked in both systems.