Hydrologically induced seasonal changes in cypress forest aquatic fauna communities. Shawn E. Liston, Nicole M. Katin & Jerome J.

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1 Hydrologically induced seasonal changes in cypress forest aquatic fauna communities Shawn E. Liston, Nicole M. Katin & Jerome J. Lorenz

2 The Big Cypress Region Little is known about the long-term history of Big Cypress wading bird population Although large rookeries have never been documented in BCNP, it serves as a major foraging ground for many species of wading birds (esp. wood storks)

3 Wading Birds in Big Cypress Locations of large colonies ( 50 nests) ( 3 of past 6 years) BCNP Wood Stork Mixed

4 Wading Birds in Big Cypress Locations of large colonies ( 50 nests) ( 3 of past 6 years) BCNP Wood Stork (50 km) Mixed (10 km)

5 Wading Birds in Big Cypress Locations of all large colonies ( 50 nests) (in past 6 years) BCNP Wood Stork (50 km) Mixed (10 km)

6 Wading bird prey Wading birds need high-density prey patches with relatively shallow water (prey accessible) Microtopographic variation is critical for creating these prey patches Topography of the Big Cypress Region is different from that of Everglades graminoid wetlands; long-distance movements of fish are impeded by topography (Gawlik 2002)

7 Everglades National Park Big Cypress National Preserve More continuous matrix More compartmentalized

8 Wading bird prey Wading birds need high-density prey patches with relatively shallow water (prey accessible) Microtopographic variation is critical for creating these prey patches Topography of the Big Cypress Region is different from that of Everglades graminoid wetlands; long-distance movements of fish are impeded by topography?? (Gawlik 2002) Big Cypress is not well-studied -- we know relatively little about how aquatic fauna respond to hydrology in this region

9 Objective to describe seasonal changes (with hydrology) in aquatic fauna community in BCNP ( )

10 Study Sites & Design 3 sites (3 replicate 1-ha plots per site) Sampled 5X annually Early-wet season* (Jul/Aug) Mid-wet season (Oct) Transition (Dec) Mid-dry season (Jan/Feb) Late-dry season (Mar/Apr) * 2 nd year only

11 Stratified sampling 250 m 250 m

12 Stratified sampling 250 m 250 m

13 Stratified sampling 250 m 250 m

14 Stratified sampling 250 m 250 m Wet prairie (inundated ~5 mo/yr)

15 Stratified sampling 250 m 250 m Intermediate hydroperiod (inundated ~8 mo/yr)

16 Stratified sampling 250 m 250 m Long-hydroperiod (inundated >10 mo/yr)

17 Stratified sampling 250 m 250 m Deep-water refuge (continuously inundated)

18 Stratified sampling 250 m 250 m Wet prairie Intermediate hydroperiod Long hydroperiod Deep-water refuge

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20 Seasonal variation in fauna density Ln (total density (no./m 2 ) + 1) Amphibians Fish Invertebrates 0 Sep 05 Jan 06 May 06 Sep 06 Jan 07 May 07 Sampling Date

21 Seasonal variation in macroinvertebrate density Everglades crayfish Everglades crayfish decrease through hydrologic year; Slough crayfish increase through mid-dry season, then decrease sharply Ln (density (no./m 2 ) + 1) Slough crayfish Grass shrimp increase through the hydrologic year Grass shrimp Wet Season Dry Season Wet Season Dry Season

22 Seasonal variation in invertebrate community structure Stress = 0.06 BI slightly different than other sites Bear Island Raccoon Point Similar pattern among sites L-28 Early-Wet Mid-Wet Transition Mid-Dry Late-Dry Community structure changes throughout the season Hydrologic Season Standardized (independent of abundance)

23 Seasonal variation in fish density Ln (density (no./m 2 ) + 1) Eastern mosquitofish Flagfish 3 2 Warmouth Densities of all fish species increased through the hydrologic year Wet Season Dry Season 0 Wet Season Dry Season

24 Seasonal variation in fish community structure 3 Sites were different, but displayed similar shifts through the season Bear Island L-28 Community structure changes a lot early in the season, less change later Raccoon Point Early-Wet Mid-Wet Transition Hydrologic Season Mid-Dry Stress = 0.12 Late-Dry Standardized (independent of abundance)

25 Spatial variation Variation in fish and macroinvertebrate communities among sites was subtle Fish were not different between zones (used all habitat available) Invertebrate density was highest in shorter hydroperiod zones (wet prairie & intermediate hp) 250 m

26 Conclusions Macroinvertebrates (Everglades crayfish) dominate aquatic fauna biomass early in the hydrologic season (short hp wetlands); fish and grass shrimp dominate late in the season Water Depth Grass shrimp Everglades crayfish Slough crayfish Fish Tadpoles Density Wet season Dry season Cypress domes & strands provide critical dry-season refuge for aquatic fauna (fish & shrimp) --- high-density prey patches

27 Conclusions BCNP provides important foraging grounds for wading birds Esp. tactile-feeders (invert-eaters) early in the hydrologic year BCNP may provide better wet season foraging opportunity than eastern freshwater marshes Wading birds do forage in cypress forests, especially in the mid- to late dry season BCR aquatic fauna community is very sensitive to hydrologic variation; Due to topography BCR may be more sensitive to restoration than other parts of the Everglades system

28 The Big Picture Studies suggest that Everglades water management practices have resulted in a shift from a system dominated by tactile-feeding wading birds, to a system dominated by visual-feeders Increase in % tactile feeding wading birds is an indicator of ecosystem health (Frederick et al. 2008) Tactile feeders (esp. White Ibis) tend to be more dependent on macroinvertebrates Data from this study (and others) suggest macroinvertebrates dominate fauna standing crop in short hp wetlands The loss of short hp wetlands throughout the Greater Everglades is likely linked to this shift in wading birds

29 Implications & future work Future work will focus on delineating the relationship between short-hp wetlands and Wood Stork nesting success BCR s short-hydroperiod wetlands are undervalued value for foraging wading birds must be considered in development & mitigation decisions What about wading birds in BCNP? What about ORV trails?

30 Thanks to RECOVER: Jennifer Stiner, Jana Newman, Vic Engel, Elmar Kurzbach, Pamela Telis, Eliza Hines ENP & BCNP: Sue Perry, Bill Loftus, Ron Clark, Bob Sobczak Audubon: David Green, Ed Carlson, Jason Lauritsen & John Ogden Colleagues: Dale Gawlik