Octopus Marine Ecology Centre

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Marine Ecology Centre - Past Events

You have reached the Low Tide Day 2001 Image Gallery

Our local Low Tide Day 2001 was held on May 27th in Cowichan Bay. The event was a collaboration of the Cowichan Community Land Trust, the Marine Ecology Centre, the Cowichan Bay Improvement Association and the Cowichan Valley Naturalists’ Society. Support was provided by the Public Conservation Assistance Fund (Habitat Conservation Trust Fund), Island Savings Credit Union, and many local businesses as well as volunteers

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In the morning some 20 volunteers traveled by land and sea to comb ten kilometers of beaches for garbage and debris. 200 kg was collected, less than 1/10th of the volume in the previous year. Either people are being better stewards or last year’s cleanup represented an accumulation over many years


 

 
 

  

 

In the afternoon 30 volunteers joined biologists Bill Austin and Cheri Ayers to assess the clam populations on Kilpahlas Beach. Before Cowichan Bay became polluted, members of Cowichan Tribes participated in a major commercial clam fishery on this beach. We assessed the clam populations by digging and sieving the mud in 0.2 square meter plots at intervals of 0.5, 1.0, 1.5 and 2.0 meters above the lower low tide level


  

 
The numbers of clams was multiplied by five to estimate the numbers per each square meter. The results are shown on the data sheet below.

Critter Count during Low Tide Day 2001 RESULTS
Centre No.: 20 /01
Purpose: To determine the number of species and numbers of animals at various tide heights on a beach
Location: seaward of the canoe shed on Kilpahlas Reserve
Latitude start: 48 o 44.47 'N; Longitude start:123 o 36.84 'W
Intertidal Heights: 0.5m 1.0m 1.5m 2.0m
Predicted tide level: 0.3 m at 1500 PST; TOTAL tide range :0 to 4 m
Date: May 27, 2000 Time start: 1300 finish: 1500
Survey Team: 2 leaders (Bill Austin & Cheri Ayers) + 28 volunteers

General Habitat: Marine Estuarine Intertidal Subtidal Benthic Neritic
Substrate: Bedrock Boulder(25+cm) Cobble(6 25cm) Pebble(1/2 6cm)
Granule(2 4mm) Sand(<2mm) Mud Shell Other
Profile: Cave Overhang Vert. Horiz. >45o 45 10o <10o
Weather: Sunny Overcast Fog Drizzle Rain
Wave Exposure: Protected Semi protected Semi-exposed Exposed
Offshore swells: None <1/2m 1/2-1m 1-2m >2m
Sea state: Glassy Ripples Wavelets Whitecaps White horses
Max. Tidal Currents[knots from charts] ? 1-2 >2-3 >3-4 >4-5 >5-6
Surface organisms: Eelgrass [Zostera marina] abundant at low water; Sea lettuce [Ulva sp.] common at lower tide level

NUMBER OF ANIMALS PER SQUARE METER based on counts per 1/5 sq. meter

Common Name 0.5 1.0 1.5 1.5 2.0 2.0 Meters
 

 

 

 

 

 

 

 

Basket Cockle 15            
Native Littleneck 15 75 120 120 20 80  
Manila Clam 5     50 25 25  
Butter Clam * 20 25   25      
Horse Clam *   5          
Soft-shell Clam     15 35 5    
Bentnose Clam 60 180       5  
Dented Clam 10   90 40 45 20  
Japanese Varnish Clam     5   15    
Baltic Clam         15    
Other Clam              
TOTAL CLAMS

125

85

30

70

25

30

 

               
Ghost Shrimp              
Blue Mud Shrimp              
Ice Cream Cone Worm              
Bamboo Worm              
Thread worm ** 60            
Scud [beach hopper] **              
Tan Proboscis Worm **   5 50        
Giant Sand Worm 5         20  

*These clams can live deeper than our survey depth, and so some may have been missed.
**represents several possible species