Habitat and biota

1. Habitat and biota FISH 7380- Dr. e.r. irwin

2. Goals • Review relations between biota and fluvial habitats • Understand the what and why of HSC (and other tools. • Look at a bigger picture: spatial and temporal riverscape structure

3. It’s the habitat, silly. • Stream biota as habitat specialists • "...most fishes of small streams are habitat specialists" (Gorman and Karr 1978) • - Evidence for habitat-specificity • Habitat-use assessments (a lot!) • Relative to availability • Interspecific differences • Experimental manipulation (a few, e.g. Meffe and Sheldon 1990)

4. Biotic versus abiotic • Communities are the result of biotic forces acting to to maintain communities at or near equilibrium. • Communities are maintained by highly variable and unpredictable abiotic forces

5. Stream fishes are habitat specialists • Evidence for habitat-specificity • Habitat use studies 70-80’s • Habitat use assessments • Experimental manipulation (Meffee and Sheldon) • Ongoing work… • Community structure related to habitat • Species use a subset of available habitat • Similar species use different subsets

6. PCA Low overlap among adults and juveniles Moyle and Vondracek 1985

7. Habitat gradients SREL

8. Suckers-Kwak and Skelly (1992)

10. How to use these data in management… • Premise: changes in habitat will lead to predictable changes in fish assemblages. • HSC: habitat suitability curves • PHABSIM: habitat models • Progression to more complicated models (2-d  3-d models) related to computer power and GIS

12. HSC • Modde and Hardy (1992)

13. Problems with application: mobile vs sedentary animalse.g.,Lazer and Madison (1995)

14. Spatial and temporal variability • Fish are flexible • Use depends on availability and quality • Example-foraging minnows • Again points to complexity of defining what habitat is • Functional relations need to be defined in terms of scale

15. Season/lifestage variation • Patch concept • Connection important • Ontogenetic shifts

16. Riffle Run Pool Percina sp. “Halloween darter” Adults 246 153 1 Percina sp. “Halloween darter” Juveniles 80 94 12 Percina nigrofasciata Adults 12 13 13 P. nigrofacista juveniles 7 7 29 Stream and species-variation

17. Well if we can’t K.I.S.S… • Guild approach • Lobb and Orth (1991)

18. Aadlund (1993) • Guilds in MN streams • 6 habitat guilds • Orth et al; still working on this • HSCs in new M.S. thesis… • stay tuned

19. Critical habitat features • "The key to understanding patterns of community diversity among stream fishes may be the definition, understanding, and measurement of relevant habitat characteristics under the influence of of seasonally dynamic physiochemical conditions". (Gorman and Karr 1978)

20. Bain et al.; 5 habitat types

21. Identify habitat characteristics most relevant to biota, • Strong temporal component • Habitat structure is a template for population and community • reproduction, energy flow, spp. interactions  • Habitat effects on those processes may vary through time and across systems: • extreme levels

22. Source/Sink—Maintain function • Organisms may specialize on particular habitats because other habitats (in that time-place) don't supply function (as well). • River management should be aimed at maintaining function.

23. Critical habitat types • Hydraulic units • Rabeni and Jacobson • Bottlenecks and configuration • Other new approaches • “Natural Flow Regime” and management of function

27. Temporal variation streamflow

28. Spawning Windows Number of YOY/100 PAEs Longest period without hydropeaking July-August (hours)

29. Availability of shallow habitats is high in a hydropeaking reach of the Tallapoosa River… PHABSIM data; Freeman, Bowen, Bovee and Irwin, 2001, Ecol. Appl. 11:179-190 Habitat availability, April-June, based on hourly flows

30. But hydropeaking greatly reduces temporal habitat stability Freeman, Bowen, Bovee and Irwin, 2001, Ecol. Appl. 11:179-190 Maximum period of habitat stability, April-June, based on hourly flows

32. a b d c Faunal response: e.g. Fish Abundance, IBI Present Threshold Base flow (during non-generation intervals)

33. Habitat template in stream systems? • Life history evolution • Morphology (smaller body sizes in turbulent habitats) • Temporal variability • Harshness shapes communities • Structure also shapes communities • RCC, lateral and landscape concepts

34. Hydrology: Characterizing Streamflow • Objectives: • Acquire basic tools for characterizing streamflow regimes

35. What hydrology means to a stream ecologist: Environmental variability through time. • Poff and Ward 1990: "The long-term regime of natural environmental heterogeneity and disturbance may be considered to constitute a physical habitat template...that constrains the types of species attributes appropriate for local persistence."

36. Where hydrologic data come from, and what they look like. • http://water.usgs.gov • U.S. Geological Survey, Water Resources Data - • your state, Water Year 19xx • years start in October

37. Five components of a flow regime, and some tools for analyzing them • Magnitude - annual means, seasonal means, CV's

38. 1984-1997 AAD = 72.5 m3/s

39. Hourly flow-R.L. Harris Dam

40. Frequency • Proportion of years when a given event is equaled or exceeded • frequency curves

41. Duration

42. Duration

43. Two more things • Timing • Rate of change

44. IHA

45. Finding hydrologic pattterns among streams • 3 gradients: • high to low flood frequency • high to low flood predictability • intermittent to perennial flow  • Ecological characteristics of fish assemblages (at least) may correspond to hydrology Bayley and Li (1992)