RNR 4040 Quiz 4

Management process

Goals, objectives, problem id, actions, evaluation

Habitat objectives

reproductive habitat (substrate/groundwater), larval and juvenile nursery habitat, cover, invertebrate habitat)

Biota objectives

fish assemblage composition, abundance, growth, invertebrate production

Human user groups objectives

access, participation, economic impact

Assessment

When objectives have been development, the next step is to identify obstacles that make achieving the objectives problematic

Sampling of habitat, biota, and human users must be designed such that ______ is maintained among years or water bodies so that data reveal actual changes in the parameters of interest.

Consistency

Parameters of interest for assessment

Time of year (river stage) or day, gear type and specifications, Sampling locations, Effort (people)

another important consideration is ________ of the data; bias is inherent in any sampling method; data collected for a particular parameter must be representative of the stock or habitat, or at least consistently biased

representativeness

Stream order

Strahler (1957)

Channel Form

related to stream sinuosity, A’/A over a reach of 20X channel width; increasing sinuosity (>1.3) —> better habitat diversity

Stream Width and Depth

wide streams usually provide more habitat types; depth variability important for habitat and biota; productive streams support a diversity of pool, glide, and riffle organisms

Flow velocity (cm/sec)

varies inversely with depth. high of this in riffles maintains DO as well as macroinvertebrate production and drift

Mean velocity

60% when depth is <1 m, 20% + 80% when depth is >1m

Variability is (coefficient of variation, σ/μ) _______ than the mean

more important

Discharge

the volume of water passing a point in the stream per unit time (m³

Velocity (discharge)

V, gives us cm or m/sec

Cross-sectional area

A, multiplied with Velocity

Discharge Formula

Q = V x A

discharge with change with ______, as will _______ and _______

stream stage (water level), velocity profile, the channel cross-sectional profile

as with velocity, total stream discharge may be important, but the ______ and _______ of discharges among cells will tell you more about __________

distribution, variability, potential fish and invertebrate habitat

Stream gradient

extremely important feature that influences stream morphology and function

Gradient is measured with a

clinometer or a transit and stadium

Substrate

particle size positively related to flow velocity, ranging from fine (like pebbles) to large (like boulders). important for reproduction and velocity/predatory cover

Gravelometer

visual surveys near transect points

Wentworth particle scale

quantitative core samples

Substrate embeddedness

how much coarse particles are buried, estimated as percentage of rock surface covered by sediment, or buried depth divided by total rock depth

Woody debris

important for periphyton/biofilm substrate, stream morphology, and invertebrate and fish habitat/cover

normally quantified as number, length, position, diameter along transect

Bank characteristics, overstory cover

vegetations important for shading, bank stability, and allocthonous input

How are bank characteristics quantified?

Bank height, channel width, Bank angle, bank cutting, channel incision

Overstory is measured with a

densiometer

Microhabitat characteristics normally measured along longitudinal or perpendicular _____, generating 30-100 measurements along a stream reach

transects

Important info about transects

if habitat measurements are qualitative (substrate estimation), it is important that all data be collected by the same person to reduce bias/repeatability

Complicating problem with transects

we can easily measure these variables in a stream reach, and they may generally be associated with species presence or absence, but are they really important to an individual fish or mayfly? if we really want to know the microhabitat preferences of fishes, we need a different methodology.

Water quality

a part of stream habitat assessment protocols because fish absorb things thru their gills

In situ

In the site. T⁰, DO, specific conductance, pH, turbidity

Another important assessment for watershed characteristics

GIS-Based assessment

How are fishes normally quantified?

electrofishing, seining, light traps, plankton nets (for larvae), and piscicides (rare)

Calculating Species Richness

number of species (S)

Calculating Fish Diversity

H ′ = -∑ p_{i (s, i=1)} lnp_i

Calculating Fish Evenness

J ′ = H ′ / lnS

Another data we collect on fish

Trophic and reproductive guilds

We could also get substantial info from fishes themselves

Otoliths, Stomach contents, Stock ID, Gonad weight/fecundity, and Fish Health

Fish Abundance

If possible, we would like to know fish density/stock size before we develop a management plan

feasible in certain situations, particularly small streams

_______ sampling is possible when the proportion of individuals captured (CPUE) within a ______ area is high

Depletion (multiple pass), defined

CPUE

Catch per unit effort

Abundance Assumptions:

Closed pop, A sampling pass removes a significant proportion of resident fish(es), CPUE declines with successive passes, All members of the pop are equally vulnerable (size?), Catachability, q, is constant between sampling passes

Regression-based models to estimate pop size

Constant q:

C_t = qfN_t

N_t = N_o - K_t

C_t/f_t = qN_o - qK_t

Regression-based methods have been replaces by maximum likelihood estimators because

problems with declining q during successes passes (the changing relationship between CPUE and accumulated catch due to variations in q is not included in the classic linear models)