Tuesday, July 16, 2013

Ddolan Day 3: Life Among the Docks

Day three – exploring the life along the docks.

Today was a scorcher!  Hot, hot, hot!  Clear skies, no wind to speak of and high humidity.  We started out observing and discussing  tidal zones between Commercial Peer and Long Wharf.  The tidal zones (supratidal, intertidal, subtidal zones) were explained as follows: “The supratidal zone is the area above the high tide water line. The intertidal zone is the area that is exposed to the air (twice daily) at low tide and submerged at high tide. The subtidal zone is the area below the low tide water line. This area is always covered by water”1

The tide was low and coming in and the water was clear to a depth of approximately 3 to 4 feet.  Gobs of what appeared to be Rockweed was plentiful and green algae.  We moved along Long wharf observing the organisms living on the rocks and dock. The organisms living along the dock were varied and plentiful as they are always in the water and are exposed to the sun for most of the day. Here we observed barnacles on the dock pilings, which I believe were native barnacles because tops of the plates were smooth (not scalloped).   We also observed mussels, some type of sea lettuce, various organisms that appeared to some type of kelp and/or seaweed along with an orange organism that appeared to be spongy in nature.  We continued our walk down to Rowes Wharf where we observed the life growing under the docks.  The growing here were again, muscles, some brown/maroon sea lettuce, common star fish, muscles, barnacles and more orange stuff that I believed and still believe was orange sponge was later (told) identified as orange truncate, but without the benefit of a microscope, the identity of the orange organism was in question.  However, after considerable research, I believe the growth to be:  Compound tunicate, colonial tunicate; bright orange to red or purple in color; reaches up to 10 cm; gelatinous colonies form dense clusters.  Pathway: introduced from Asia; from the Pacific in the 1970s, found in waters from Maine to Virginia; reported in LIS (1980's), Impact: fouling organism - attaches to boat hulls, piers, lines, traps, buoys, seaweeds. 2

We continued out walk to the docks at the Barking crab where we observed the same organisms previously spied, but here we were able to pull or cut off samples for closer observation.  At the Barking Crab we pulled what I believed to be golden star tunicate, red alga, sea lettuce, kelp, and sea grapes .  We also observed what appeared to be feather duster, and insects identified as amphipods, barnacles, lichen,  but accurately identifying the various organisms by looking at a picture in a book is nearly impossible, so I’m still unsure of what I observed.

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