Friday, December 30, 2011
Marine Event of the Year - 2011 Tropical Storm Irene
Tropical Storm Irene hit New England on August 28th, 2011 with onshore winds on the east side of the storm battering coastal areas with large waves and a destructive storm surge. After the storm, I traveled to Provincetown during calm weather and monitored the docks at Provincetown and Wellfleet on August 31st and September 1st.
Tropical Storm Irene Hits New England
Tropical storm Irene over New England brought onshore easterly winds
and turbulent waters to the Massachusetts coastline.
Satellite view over the Northeastern US with outlines of the states superimposed. The image was taken when the eye of the storm was near New York City.
Left, projected path of Hurricane Irene when it was in the Carribean. Irene started its journey as a hurricane in Puerto Rico, made landfall over eastern North Carolina's Outer Banks, and was downgraded to a tropical storm as it passed over Long Island, NY. Right, it continued through western New England battering CT and VT. The threat level through the Northeast was extreme with widespread damaging winds through August 29th.
The storm had a significant effect on marine life on the sides of docks, scouring off loosely attached organisms and battering firmly attached species. Most of the colonial species and algae that extended away from their attachment site were pruned or torn off and some species appeared bruised or damaged. Firmly attached species like Styela clava and Codium fragile survived the storm, but filamentous and leafy algae were washed away or pruned shorter taking with them the species (e.g., amphipods) that grew on or among them. Outgrowths of Didemnum vexillum were torn off at the base, as were large colonies of Botryllus schlosseri and Botrylloides violaceus. In Wellfleet, an almost solid covering of a spring cohort of Molgula sp.(manhattensis?) on portions of the seasonal docks was decimated resulting in large areas of the docks being cleared of the ascidian.
Monitoring at MacMillan Wharf, Provincetown, 2 Days after the Storm
Inspecting colonial organisms on August 31st using the palm of my hand to make a small pool of water and preparing to magnify the field with a jeweler's loupe.
A month later, by the September monitoring visit, there was a clear re-colonization of the depleted areas in Provincetown by algae, ascidians, and other invertebrates. Didemnum vexillum grew up the sides of the dock from established areas lower on the dock, and Diplosoma listerianum, not found at the beginning of the season, surged in its colonization from its first sighting in August. Botryllus and Botrylloides repaired their torn edges and resumed their previous growth. Near the water line, small individuals of Styela clava (under 1 or 2 inches) were scattered along the dock on newly exposed substrate. In Wellfleet, there was no noticable re-colonization of cleared surfaces by Molgula, but Botryllus schlosseri growing on the remaining Molgula continued to grow and spread, and there was some regrowth of algae and other attached species along the water line.
Posted by Thomas Ermak