Relationships Between Tidal Height and Species Abundances: Implications for
Monitoring Rocky Shores
Steve MurrayCSU Fullerton
Urban Influences
-4
-3
-2
-1
0
1
2
3M
ean
Mon
thly
An
om
alies (
°C)
19501955 19651960 1970 1980 19901975 1985 1995
Warm Regime
Coastal Sea Temperature
Urban Influences?Fishing Pressures?
Changing Sea Temperatures?Changing Sea Level?
Changes in Intertidal Communities
Tides: Daily RegimeMixed Semi-diurnal Character
Tides: Monthly PatternsNeap and Spring Tides
SPRING NEAP NEAP SPRING
Tide Levels
Fee
tZero Datum = 0.0
ft
Highest of High Tides
= HHHW OR EHWS
Lowest of Low Tides
= LLLW OR ELWS
MTL or MSL (Mean Tide Level or Mean
Sea Level
Source: Doty, M. S. 1946. Critical tide factors that are correlated with the vertical distribution of marine algae and other organisms along the Pacific Coast. Ecology 27: 315-328.
Zonation and Critical Tidal
Levels (Max Doty)
Zonation
Quadrat Sampling
Line Point Contact Sampling
Source: Littler, M. M. and S. N. Murray. 1975. Impact of sewage on the distribution, abundance, and community
structure of rocky intertidal macro-organisms. Mar. Biol. 30: 277-291.
Zonation Patterns Quantified
Tid
al H
eigh
t
Species
Measuring Tidal Heights of Samples
Measuring RodLaser Target
Laser Level
Calibrate Vertical Height on Shore with
Tidal Datum
Acknowledgements
Field and Lab Assistance: Janine Kido, Teri Denis, Jayson Smith, Everett Yee, Susan Frisch, Sarah Henkel, Erin Cox, Lisa Gilbane, Aimee Bullard, Amanda Gerrard, Julie Bursek, Jill Moeller, Tiffany Luas, Nicolle, Panos, Alison Kendall, Megan Williams, Erin Maloney, Kristen Kusic, Haven Livingston