Habitat and biota FISH Dr. e.r. irwin

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

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)

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

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

Moyle and Vondracek 1985 PCA Low overlap among adults and juveniles

Habitat gradients SREL

Suckers- Kwak and Skelly (1992)

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

HSC Modde and Hardy (1992)

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

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

Season/lifestage variation Patch concept Connection important Ontogenetic shifts

Stream and species-variation RiffleRunPool Percina sp. “Halloween darter” Adults Percina sp. “Halloween darter” Juveniles Percina nigrofasciata Adults1213 P. nigrofacista juveniles7729

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

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

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)

Bain et al.; 5 habitat types

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

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.

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

Temporal variation streamflow

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

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: Habitat availability, April-June, based on hourly flows

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

Base flow (during non-generation intervals) Presen t Faunal response: e.g. Fish Abundance, IBI Threshold ab c d

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

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

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."

Where hydrologic data come from, and what they look like. U.S. Geological Survey, Water Resources Data - your state, Water Year 19xx years start in October

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

AAD = 72.5 m 3 /s

Hourly flow-R.L. Harris Dam

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

Duration

Two more things Timing Rate of change

IHA

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)