Monthly Archives: April 2005

Stratified Tidal Flow over a Bump- Richard Dewey

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doi: 10.1175/JPO2799.1
October, 2005,
Journal of Physical Oceanography: Vol. 35, No. 10, pp. 1911–1927.

Stratified Tidal Flow over a Bump
RICHARD DEWEY
School of Earth and Ocean Sciences, University of Victoria,
Victoria, British Columbia, Canada
DAVID RICHMOND AND CHRIS GARRETT
Department of Physics and Astronomy,
University of Victoria,
Victoria, British Columbia, Canada
(Manuscript received 8 October 2004, in final form 22 April 2005)

 

ABSTRACT: The interaction of a stratified flow with an isolated topographic feature can introduce numerous distur- bances into the flow, including turbulent wakes, internal waves, and eddies. Measurements made near a “bump” east of Race Rocks, Vancouver Island, reveal a wide range of phenomena associated with the variable flow speeds and directions introduced by the local tides. Upstream and downstream flows were observed by placing two acoustic Doppler current profilers (ADCPs) on one flank of the bump. Simulta- neous shipboard ADCP surveys corroborated some of the more striking features. Froude number conditions varied from subcritical to supercritical as the tidal velocities varied from 0.2 to 1.5 m s1. During the strong ebb, when the moored ADCPs were located on the lee side, a persistent full-water-depth lee wave was detected in one of the moored ADCPs and the shipboard ADCP. However, the placement of the moorings would suggest that, by the time it appears in the moored ADCP beams, the lee wave has been swept downstream or has separated from the bump. Raw ADCP beam velocities suggest enhanced turbulence during various phases of the tide. Many of the three-dimensional flow characteristics are in good agreement with laboratory studies, and some characteristics, such as shear in the bottom boundary layer, are not.

Dewey-RG-Bump-JPO2799

See the full version of this paper at:

ftp://canuck.seos.uvic.ca/papers/Dewey-RG-Bump-JPO2799.pdf

Canadian Geographic Kids Program

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The CBC TV crew accompanied us on a dive to Race Rocks in order to video a sequence that later was used on the nationally televised Canadian Geographic Kids program.

Solmissus marshalli –The Race Rocks Taxonomy

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solmissus

Solmissus sp. taken from the video linked below.

Solmissus marshalli lives in the midwater zone of seas. It feeds by swimming slowly with its tentacles stretched out. When animals bump into the tentacles, stinging cells fire and hold on. Depending on the size of the prey, it can take a jellyfish up to two hours to move food from its tentacles to its stomach. The jellyfish feeds on gelatinous animal plankton, other jellies and copepods. It is a secondary consumer.

In this video you can see two different species of jellyfish, Solimissus marshalli and Mitrocoma cellularia. These invertebrates are part of the phylum Cnidaria which include hydroids, scyphozoan jellyfishes, sea anemones, sea pens and corals. They are constructed of 2 layers of cells-the outer covering and the inner covering of the digestive cavity. Between is a jellylike layer (mesoglea). Some cells are specialized for digesting or stinging. The jellyfish is the sexual ‘medusa stage’ of a hydroid. The hydroid medusa has a membrane (velum) that grows inward from margin of the bell. Most of the 60 or so local jellyfishes are medusaes of hydrozoans; surprisingly very attractive, but usually very small and they often go unnoticed. These specimens were videoed by Jean-Olivier Dalphond and Damien Guihen on a sunny day of June 2001. Identification was by Dr. Anita Brinckmann-Voss. Anita regularly samples the waters of Race Rocks as well as nearby Eemdyck passage, Beecher Bay , Pedder Bay and Sooke harbour where the upwelling water from the Strait of Juan de Fuca often brings numerous medusae.

Species recognized by World Register of Marine Species (WoRMS) Biota Animalia

Cnidaria

Hydrozoa , Owen

Narcomedusae Haeckel 1879

Cuninidae Bigelow 1913

Solmissus

Solmissus marshalli Agassiz & Mayer, 1902

See this link for other hydroids:  https://www.racerocks.ca/tag/hydroid/
Other Members of the Phylum Cnidaria at Race Rocks.

taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams. 

Lester B. Pearson College:
2005 Debra Quek PC Yr 31

 

 

Mitrocoma cellularia : jellyfish – Race Rocks Taxonomy

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mitrocoma

Mitrocoma cellularia


In this video you can see two different species of jellyfish, Solimissus marshalli and Mitrocoma cellularia. These invertebrates are part of the phylum Cnidaria which include hydroids, scyphozoan jellyfishes, sea anemones, sea pens and corals. They are constructed of 2 layers of cells-the outer covering and the inner covering of the digestive cavity. Between is a jellylike layer (mesoglea). Some cells are specialized for digesting or stinging. The jellyfish is the sexual ‘medusa stage’ of a hydroid. The hydroid medusa has a membrane (velum) that grows inward from the margin of the bell. Most of the 60 or so local jellyfishes are medusaes of hydrozoans; surprisingly very attractive, but usually very small and they often go unnoticed. These specimens were videoed by Jean-Olivier Dalphond and Damien Guihen on a sunny day of June 2001. Identification was by Dr. Anita Brinckmann-Voss. Anita regularly samples the waters of Race Rocks as well as nearby Eemdyck passage, Beecher Bay , Pedder Bay and Sooke harbour where the upwelling water from the Strait of Juan de Fuca often brings numerous hydroid medusae. 

From NCBI taxonomy

See this link for other hydroids:  https://www.racerocks.ca/tag/hydroid/ Link to the Race Rocks Taxonomy index

This file is provided as part of a collaborative effort by the students, faculty, staff and volunteers  of 
 Date:
2005		 Garry Fletcher

Installation of Succession plates for the Tidal Energy project

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This video shows the installation process for the tidal energy generator research project. This was carried out by Chris Blondeau and the Pearson College Divers in order to determine which surfaces discouraged growth in the waters at Race Rocks. As a result, Titanium was used in the construction of some parts of the generator as it was one of the metals most resistant to fouling.

See other archived video with Pearson College Divers

Link to the Integrated Energy Project

Caprella laeviuscula: Caprellid shrimp– The Race Rocks Taxonomy

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We found these Caprellids at a depth of 20 metres attached to hydroids on a Balanus nubilus. They frequently dwell amongst hydroids. The size of this individual was 3mm. These individuals were photographed using a Motic Digital Microscope at 10X magnification. Note the response to stimulation by a dull probe.

In the picture below , the current meter float which was in the water for a year, came up covered with Caprellids. See this file on the Current meter:

Look closely to see these tiny skeleton shrimp clinging to bryozoans, hydroids or algae. Their body shape and color help the shrimp to blend into their background. Their bodies are long, cylindrical and range from pale brown and green to rose. Some species can quickly change color to blend into their backgrounds.

Skeleton shrimp look like, and sometimes are called, “praying mantises of the sea.” They have two pairs of legs attached to the front end of their bodies, with three pairs of legs at the back end. The front legs form powerful “claws” for defense, grooming and capturing food. The rear legs have strong claws that grasp and hold on to algae or other surfaces. They use their antennae for filter feeding and swimming.

Diet
diatoms (microscopic plants), detritus, filtered food particles, amphipods 
Size
to 1.5 inches (4 cm) long 
Range
low intertidal zone and subtidal waters in bays,

Conservation Notes

Skeleton shrimp are abundant and live in many habitats, including the deep sea. They play an important role in the ecosystem by eating up detritus and other food particles. 

Cool Facts

Shrimp, sea anemones and surf perch prey on skeleton shrimp. The females of some skeleton shrimp species kill the male after mating. 

Skeleton shrimp use their front legs for locomotion. To move, they grasp first with those front legs and then with their back legs, in inchworm fashion. They swim by rapidly bending and straightening their bodies. 

To grow, skeleton shrimp shed their old exoskeletons and form new, larger ones. They can mate only when the female is between new, hardened exoskeletons. After mating, the female deposits her eggs in a brood pouch formed from leaflike projections on the middle part of her body. Skeleton shrimp hatch directly into juvenile adults.

Source: Monterey Bay Aquarium:
Online Field Guide http://www.mbayaq.org/efc/living_species/default.asp?hOri=1&inhab=521

Other Members of the Phylum Arthropoda at Race Rocks.

taxonomyiconReturn to the Race Rocks Taxonomy and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams. This file was originally started by Kevin Mwenda PC Yr 31

Deploy and Retrieve ADCP Instrument 2005

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In order to predict the best location for the installation of the tidal power generator, an ADCP ( Acoustic Doppler Current Profiler) supplied by ASL Environmental Sciences was deployed. This instrument will collect current regime information for a period of one month. Rita Santos did the video and Angie Karlsen helped Chris Blondeau lift and position the concrete weights used to secure the device on the sea floor..

See other archived video with Pearson College Divers

Anthopleura xanthogrammica: Giant Green Anemone–The Race Rocks Taxonomy

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rmintertidalanem

Anthopleura xanthogrammica : photo by Ryan Murphy

Physical Description: As says its name, the Giant Green Anemone is the largest green anemone. The diameter of its column can easily reach 175 mm and its height, 300 mm. The column is covered with adhesive tentacles that are short and conical. The green color of the anemone changes, from bright green to a dark greenish brown.

Global Distribution: Anthopleura xanthogrammica lives in the tide pools along the Pacific coast. It can be found from Alaska to Panama.

Habitat: The Giant Green Anemone most likely lives on the rocks of tide pools, usually not deeper than 30 m. Also, it can be found in deep channels in exposed rocky shores.

Feeding: It eats with the help of thousands of nematocysts located on its tentacles. These paralyze the prey. Usually, the Giant Green Anemone feeds on detached mussels, crabs, sea urchins and small fishes.

Predators: This anemone can be eaten by crabs and sea stars, but its most common predator is the snail, which feeds on its tentacles or its column, and the sea spider, which feeds on its column.

Reproduction: To reproduce, Anthopleura xanthogrammica releases sperm and brownish eggs. When the larvae is formed, it swims or floats for a period of time and becomes dispersed. The reproduction of the Giant Green Anemone happens in late spring and summer
.
Interesting fact: Bright sunlight makes the green color of the anemone brighter by encouraging the algae that lives in its tissue to grow. But in the shade, the algae grows weak, making the anemone less colourful and more white in color. Also, a compound from Anthopleura xanthogrammica is now used as a heart stimulant.

Domain Eukarya
Kingdom Animalia
Phylum Cnidaria
Class Anthozoa
Subclass Zoantharia
Order Actiniaria
Family Actiniidae
Genus Anthopleura
Species xanthogrammica
Common Name: Giant Green or surf anemone

References:
Gotshall, Daniel W. Guide to marine invertebrates. Monterey : Sea Challengers, 1994.
Abbot, Donald P., Eugene C. Haderlie and Robert H. Morris. Intertidal Invertebrates of California. Stanford : Stanford University Press, 1980.
Giant Green Anemone. 1999. Monterey Bay Aquarium. 8 Nov 2005.

return to the Race Rocks Taxonomy gallery

This file is provided as part of a collaborative effort by the students , faculty, staff and volunteers of
Pearson College UWC
 Date:
2005		 by Caroline Laroche, Québec year 32

Hinnites giganteus: The purple-hinged rock scallop

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scallopnumbered

Hinnites giganteus, the purple hinged rock scallop with associated organisms,  (sponges, barnacles, hydroids etc.)

hinge

This is the “purple hinge” on an open shell of a rock scallop. It is almost obscured by the growth of other invertebrates. The yellow spots are from a parasite, the boring sponge, Cliona sp.. The white anemone is Metridium sp .The snail is Calliostoma sp.

Other Members of the Phylum Mollusca at Race Rocks.

taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.   G.Fletcher 2005

 

Branta bernicla: Black Brant Goose–The Race Rocks Taxonomy

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inwater1

Branta bernicla Black Brant Goose

The Black brant Branta bernicla is a very unusual visitor at Race Rocks. There are only single individuals that appear, usually in late summer or fall.

Pam  Birley has sent the following images taken with the remote camera 5 which we have put into a short video:

brant-moviePam  writes:
“The dimensions of the Brant are 17″ long and 46″Wingspan, A Canada goose is given as 16″-25″L and 50-68″W (which is quite a variation)
A Glaucous gull is given as 24″L and 50″W Thayer’s  are 20″L and 55” W. So according to that the gulls are all bigger than the Brant – so perhaps the camera was not lying “
The goose continued to hang out with the Canada geese for several months.

ntblackbrantnov14

Black Brant Branta bernicla at Race Rocks see posting of November 22, 2014-for other  photos by Ecoguardian Nick Townley

Physical description
The black brant is a small goose with black head, neck, breast, tail and flight feathers. Its abdomen and tail coverts are white and the back and upper abdomen tend to be brownish-black. Its weight ranges from about 1.5 – 2.7 kilograms.

Global distribution
Black brants nest along the shores of the western Arctic, where they lay eggs in June. In mid-September the young travel to the California and Mexican coasts. The main flock flies over the sea, being seldom observed in British Columbia. There is another migration that may winter as far north as Haida Gwaii. However, the majority winters off the coast lines of Oregon, California and Mexico. The favourite stops for Black Brant Geese are Sooke Harbour, Oak Bay and Sidney Island.

Habitat

Black Brant makes a landing on the heli-pad.

Branta bernicla travel in flocks. The amount of geese in a flock varies, though usually remains at low levels. The brants are considered one of the fastest flying geese.Feeding
They feed mainly on eel grass, which is a significant part of their diet. Other marine plants are also being eaten by them, such as green algae.Reproduction
Black brant’s nests are always placed along shores, never far from the water. In June they lay 4 to 8 eggs and by mid-September the young are ready for a long journey. Immature black brants lack white neck marking and are more black at the bottom.

Classification:
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Sub-Phylum: Vertebrata
Class: Aves
Order: Anserifomes
Family; Anatidae
Genus: Branta
Species: bernicla
Common Name: Black Brant Goose,also called Brent goose.

References:
1. Guiguet, C.J. (1915). The Birds of British Columbia: (6) Waterfowl. Victoria: British Columbia Provincial Museum.
2. Robbins, Chandler S., Bruun, Bertel, & Zim, Herbert S. (1966). A guide to field Identification- Birds of North America. New York: Golden Press.
3. Godfrey, E. (1986). The birds of Canada (2nd ed.). Ottawa: National Museum of Natural Sciences.
See the other posts on this website documenting Brants at Race Rocks
See the index of the Taxonomy of Race Rocks

This file is provided as part of a collaborative effort by the students, faculty, staff and volunteers  of Lester B. Pearson College  — 2005–Kamil Mika —year 32