Algal transect surveys (MEP)
I repeatedly survey permanent cross-stream transects (“x-scns”) to follow changes in algae, environmental conditions, and associated organisms over time, documenting seasonal and interannual variation. Transects are benchmarked at both ends with nails in trees or bedrock—these can be labeled with aluminum tree tags (Forestry Supply) and should be carefully located with hand-drawn maps, GPS, triangulation (measure distance to spot from two other conspicuous landmarks), etc. Benchmarks should be on ‘permanent’ structures (e.g. large trunks) high enough so that high as well as low flows can be documented (just above bank full is ideal, higher than that and it’s hard to read the tape while walking the streambed). On each survey, stretch a meter tape tightly between the nails. Nail to nail distance should vary less than 1 cm over repeated surveys. Take enough points to obtain about 15-20 measurements for each x-scn. At 0.5 m or 1.0 m intervals along each transect:
- note distance along the meter tape (X-strm (m))
- measure water depth (cm) (a ski pole marked in decimeters is good, doesn’t flex in high flow, and saves you from falls)
- measure velocity with a current meter, or estimate surface current velocity (cm s-1) by timing floating objects across your measurement point1
- note dominant and subdominant substrate particle sizes2
- using a diving mask or plexiglass view box, note the dominant and subdominant macroscopic algal taxa within an estimated 10 cm x 10 cm area around each sampling point3
- record the modal height (cm) of attached filaments or the length from point of attachment of strands of algae floating over the site on the water surface, if these obscured view of the bed.
- characterize algal density (% cover) 4
- if possible (for Cladophora, zygnematales, perhaps Nostoc) characterize algal condition5
- note conspicuous animals within the same 100 cm2 observation area, bearing in mind that some will be attracted to you (minnows) and others will be hiding (mayflies) 6.
Key–Codes and categories used:
- Flow velocity (cm s-1) (surface velocity)
code
0 0 (silt settles vertically)
5 0-5
10 5-10
20 10-20
30 20-30
50 30-50
100 50-100
>100
- Particle size (median diameter, mm)
code
M <<< 2 mm, not gritty = mud
S < 2, gritty = sand
G 2-16 = gravel
P 16-64 = pebbles
C 64-256 = cobbles
B > 256 but separate = boulder
Br continuous with landscape = bedrock
- Algal (etc.) codes
Code
Clad Cladophora (note color as green G, yellow Y or Rusty red R)
Moug, Spg Mougeotia or Spirogyra (need to distinguish under scope)
Zyg Zygnema (more chatreuse than Spg or Moug, colder water)
diat sk diatom skin (gold, orange or yellow-brown)
bg sk dark or grey skin (often Phormidium, Tolypothrix or Scytonema)
Nos b Nostoc balls (if just “Nos” is written, assume balls)
Nos e Nostoc ears (colonized and resculpted by Cricotopus midge larvae)
Riv Rivularia black freckles to larger circular spots or blotches
Anab deep turquoise to black Anabaena, loosely epiphytic on Clado
Phor Phormidium—dark brown epilithic cyanobacteria turf in riffle flow
Silt deposited organic detrital floc
Sedge dominant bunched graminoid along active channel is Carex nudata
Moss Fontinalis is long flowing moss up to 60 cm, other riverine mosses are mats
Leaves Terrestrial leaf litter
Alder green we have noted some years if the dominant alders drop green leaves
Alder brown these alder leaves would add less nitrogen to the river
- Algal density
Code
1 a few filaments
2 < 10% basal cover
3 10-50% basal cover
4 50-98% cover
5 can’t see substrate through growth
- Algal condition
Code
1 nearly detritus
2 senescent, discolored, fragile and falling apart
3 discolored but less fragile
4 slightly discolored, but robust
5 vibrantly healthy
- commonly observed Fauna (optional)
tufts (retreats of Pseudochironomus)
tube midges
Pet Petrophila, aquatic moth larvae, clear as larva, white scabs as pupa
Mayflies
Hept – heptageniids
Baet – baetids (Baetis, Centroptilum)
Ephem –ephemerellids
Siph – siphlonurids
Leps –Leptophlebiiids
Caddisflies:
Dicos Dicosmoecus caddisflies see illustrations of 5 larval instars
Oncos Oncosmoecus, similar with no saddlebag pebs at rounder aperture
Tin Tinodes tube dwelling caddis, like spaghetti
Leuco rice grain size sessile caddis
Gum Gumaga, slender curved sand cases
Neo Neophylax, stone cylindrical case
Glosso Glossosoma, turtle shell stone case
Snails
Rams – Helisoma
Physella
Goniobasis
Ferrissia — fw limpets
Fish
R roach
Stl steelhead
Stk stickleback
PM pike minnow
Su sacramento suckers