Shoreline Outing Report: Denman Island, April 24th 2019

Hey Everyone,

Yesterday’s trip to Denman intersected with ideal spring weather. We visited two bedrock  shorelines– one on the east side of the island and another on the west. Some notes to follow up on things we saw.
(1) Geology and Trace Fossils
Both shorelines were composed of alternating beds of mudstone and sandstone that were formed on the sea floor about 80 million years ago. At the first beach, we saw abundant trace fossils, particularly large, branching burrows that were broadly parallel to the layers (bedding) in the sedimentary rock. These are interpreted elsewhere in the region as the pathways that decapod crustaceans (crabs, shrimp, lobster) maps through the sediments. We also saw the well cemented ellipsoidal concretions in the bedrock where fossils have been found, though we had no luck with the one that we split.
The geology of Denman and Hornby Islands is well-studied. There is this wonderful map from the BC Geological Survey as well as studies that describe how the conglomerates, sandstones and mudstones of these islands formed on the sea floor by the movement of materials in gravity flows from submarine channels out onto the open sea floor. .
(2) Oyster Leases
On the west side of the island, we saw systems of boulder placement, rebar, rope and netting associated with oyster aquaculture. This large PDF MAP from DFO shows that we were walking one of the most intensely cultivated shores in the province. This document is an overview of the legal regulations for aquaculture as well as the licensing fee formulas. Oyster leases and operations for sale are listed on the BC Shellfish Growers website.  We saw some serious modifications and garbage related to these aquaculture operations– it will be instructive if we can figure out what the environmental obligations are for these operators.
(3) Life
We saw lots of creatures, sessile and motile, solitary and colonial. Member of the group who were there, please let me know if I am forgetting things. Some of you were taking great pictures of molluscs and their eggs. As an aside, apparently some nudibranchs (the group that includes that barnacle nudibranch) can lay MILLIONS of eggs. We should do a count next time.
Beach One- Bedrock Shoreline 1km south of Fillongley Provincial Park
Black Pine Seaweed (Neorhodomela larix)
Nori/Sushi Seaweed (Porphyra)
Sea Lettuce (Ulva)
Rockweed (Fucus)
Sea cauliflower (Leathesia)
Sea Felt (Pylaiella littoralis)
Soda Straws (Scytosiphon)
Rusty Rock (Hildenbranda)
Plumose Anenome (Metridium sp.)
Kelp Crab (Pugettia producta)
Black Clawed Crab (Lophopanopeus bellus)
Rock Crab (Cancer productus)
Oregon Shore Crab (Hemigrapsus oregonensis)
Dungeness Crab (Metacarcinus magister)– maybe graceful crab
Hermit Crab (Pagarus sp.)
Coastal Shrimp (Heptacarpus sp.)
Mossy Chiton (Mopalia muscosa)
Barnacle nudibranch (Onchidorus bilamellata)
Limpet (Lottia digitalis)
Pacific Oyster (Crassostrea gigas)
Dogwinkle (Nucella lamellosa)
Moon snail (Neverita lewisii)
Bryozoans (Schizoporella sp.)
Purple  Cockscomb (Anoplarchus purperescens)
Tidepool Sculpin (Oligocottus sp.)
Beach Two: Bedrock Shoreline at end of Hinton Road, West Side
Black Pine Seaweed (Neorhodomela larix)
Turkish towel (Mastocarpus sp.)
Sea Lettuce (Ulva)
Rockweed (Fucus)
Sea cauliflower (Leathesia)
Sea Felt (Pylaiella littoralis)
Soda Straws (Scytosiphon)
Rusty Rock (Hildenbranda)
Flatworms (Notocomplana)
Ribbon worm (Tubulanus polymorpha)
Clam Worm (Neries vexillosa)
Fibreoptic Hydroid (Abietineria greenei)
Yellow Sponge (Halichondria panicea)
Bryozoan (Schizoporella)
Violet tunicate (Botrylloides violaceus)
Wrinkled tunicate (Pyura haustor)
Midshipmen (Porichthys notatus)
Purple  Cockscomb (Anoplarchus purperescens)
Tidepool Sculpin (Oligocottus sp.)
Japanese Mud Snail (Batalaria (with Pagarus)
Moon snail (Neverita lewisii)
Sea jingle (Pododesmus)
Pacific oyster (Crassostrea gigas)
Lemon Dorid (Archidoris montereyensis)
Hind’s Chiton (Mopalia hindsii)
Bright aeolid nudibranch (Flabellina sp)
Sea star (Pisaster ochreus)
White Sea cucumber (Cucumaria pallida)
Plumose anenome (Metridium)
Big red (Painted?) anemone (Urticina grebelnyi)
See you soon,
Randal
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