Monitoring at MacMillan Wharf, Provincetown, MA

Monitoring at MacMillan Wharf, Provincetown, MA
Marine Invasive Species (MIS) Monitoring at MacMillan Wharf, Provincetown, MA.

Tuesday, October 30, 2012

MIS Floating Dock Community

Ascidians Claiming Space

On my last visit to Provincetown, I obtained a nice photograph of an invertebrate marine floating dock community at MacMillan Wharf - a shaded section of a float that was facing north, under a dock overhang, that had ascidians and other invertebrates growing together.  The upper few inches lacked a border of algae along the waterline that is characteristic of sunny locations.  It was a scene of moderate growth, before the species had a chance to completely overgrow each other into a mass of organisms (an enlargment of the whole photo is showing in the footer at the bottom of the blog).

Community of Invertebrates Below the Water Line
Species that are easily identified in the photo or enlargements:
  • Styela clava, one large individual 8-10 cm long cloaked in Didemnum vexillum and several smaller individuals about 3-5 cm long growing along the waterline.
  • Didemnum vexillum - Beige areas on the float, growing over Styela and other species. Didemnum was less abundant in 2012 than 2011. This float was one location in the marina where Didemnum was well-established and living together with Diplosoma.
  • Diplosoma listerianum - Grey-colored, flat colonies that grow on the float and over Styela.  Diplosoma was the the most abundant ascidian in Provincetown in 2012, growing on many surfaces that were dominated by Didemnum last year.
  • Botrylloides violaceus - Various small colonies, some tiny, in at least 2 shades of orange. Present everywhere but usually in limited discrete colonies. 
  • Botryllus schlosseri - A single colony can be seen in the enlargement below. 
  • Bugula neritina - A single wine-red colony about 2 cm high in the left center, immediately below a light-orange Botrylloides.
  A single mosaic-patterned colony of Botryllus schlosseri (left bottom) and a row of 5 Styela individuals (right) line up along the water line.  The first 4 Styela have clean, brown tunics whereas the 5th one on the right is partly covered by Diplosoma.    
Palaemonid shrimp can also be seen in the photo with pairs of flash-induced "white-eye" of their normally black eyes. There are 5 pairs of eyes in the photo (1 on the left side of the large Styela and 4 lined-up on the right).  
This year, a few Palaemon elegans, an MIS shrimp with blue-banded legs that is spreading throughout the Gulf of Maine, were seen at MacMillan Wharf.