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