Barnacles at Blacks Harbour

Bay of Fundy barnacle

We drove to Blacks Harbour from Saint John in New Brunswick to catch the ferry for the Island of Grand Manan. The road was good and we arrived with time to spare before our departure – and time to explore the nearby shore. The extensive tidal range, typical of the Bay of Fundy, is evident from the vertical extent of relatively bare rock between the water and the trees at low tide – especially on the small off-shore islands. On the gently sloping beach, a lichen-covered, wooden pontoon links the dry land to the water, enabling access at all times to fishing boats and rafts in the cove. The rafts provide a floating base for small huts and storage for lobster pots, nets, ropes and other fishing gear.

The shore itself is very much a working one but has probably seen busier times. An isolated crane or winch is still parked on the beach where scattered stumps of former wooden pilings, concrete mooring weights, rusty chains, and algae-covered ropes are found among the sediments and beach stones. The empty shells of deep-water scallops and mussels are strewn around; while the most visible living seashore creatures are the periwinkles and acorn barnacles. These are found on rock outcrops, boulders and beach stones, wood, and man-made objects.

The barnacles (shown in the photographs) are probably the Northern Rock Barnacle which is called Balanus balanoides in the Peterson Field Guide to the Atlantic Seashore. However,  the Northern Rock Barnacle has been re-classified since the Peterson field guide was written and its current scientific name should be Semibalanus balanoides because it has a membranous basis rather than a calcareous basis as in the Balanus genus. It is also possible that the Northern Rock Barnacles at Blacks Harbour, and elsewhere on the shores of the Bay of Fundy, are a form or sub-species of S. balanoides.

The barnacles are not profuse in this location. They caught my eye because the calcareous plates exhibit two colours or textures. A close examination reveals that the older parts of the plates have a rough texture of many perforations. The plates have been  colonised by an endolithic lichen; and the holes are the means by which the lichens shed their spores. The contrasting whiter, smoother parts of the barnacle plates at the base of the animal are the new growth which is as yet unaffected by the lichen.

REFERENCES

Gosner, Kenneth L. (1978) Atlantic Seashore from the Bay of Fundy to Cape Hatteras, The Peterson Field Guide Series, Houghton Mifflin Company, ISBN 978-0-618-00209-2.

Southward, A. J. (2008) Barnacles, Synopses of the British Fauna (New Series) No. 57, edited by J.H.Crothers and P.J.Hayward, published by Field Studies Council for The Linneaen Society of London, and The Estuarine and Coastal Sciences Association, ISBN 978-1-85153-270-4.

Bay of Fundy barnacles on wood with periwinkles and seaweed

Bay of Fundy barnacles on wood with periwinkles

Bay of Fundy barnacles on wood with periwinkles

Bay of Fundy barnacles on wood with periwinkles

Bay of Fundy barnacles on wood with periwinkles

Bay of Fundy barnacles on wood with periwinkles

Bay of Fundy barnacles on wood with periwinkles

Bay of Fundy barnacles on rock

Bay of Fundy barnacles on rock

Bay of Fundy barnacles on rock

COPYRIGHT JESSICA WINDER 2013

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Pitted barnacle shells at Bran Point

Barnacle macro-photograph: Barnacles, Chthamalus montagui Southward, on the Bran Point rock ledge at Ringstead Bay, Dorset, UK - part of the Jurassic Coast - with shells showing pits made by the endolithic lichen Collemopsium sublitoralis (1)

Incredible sculpturings and pittings are revealed in this close-up of barnacle shells. This sort of barnacle is known as Chthamalus montagui Southward and encrusts the rocky ledge of Bran Point at Ringstead Bay in Dorset. The species is characterised by the kite-shaped opening and the shape of the four plates (terga and scuta) that make up the operculum or lid. What really intrigued me was the pit marks on the shells. These are not normal. I looked in the literature but could only find references to regular growth ridges and rows of pits on the opercular plates: that didn’t seem to fit the bill.

Then I speculated that the thick rough shells might be the result of age or external calcium deposition from solution of the adjacent limestone rocks. Maybe the pits were evidence of corrosion by acid rain or the nearby natural oil seepage.

The truth about the pits, now that I have eventually tracked it down, is more amazing than I could have imagined. There is a minute lichen called Collemopsidum sublitoralis (used to be called Pyrenocollema halodytes) which lives in and on rocks – it is endolithic. It also lives in the shells of barnacles and affects their appearance. Lichens are strange organisms which are part alga and part fungus. The pits in the barnacle shells are caused by the occupying lichen and contain the fungal fruiting bodies or perithecia of this  lichen.

Barnacles, Chthamalus montagui Southward, encrusting rocks at Bran Point, Ringstead Bay, Dorset, UK - part of the Jurassic Coast (2)

Pictured above is a general view of the encrusting layer of Chthamalus montagui barnacles. The photograph below shows the view from the same barnacle-encrusted rocky ledge of Bran Point looking eastwards acrross Ringstead Bay. 

View at Ringstead Bay: View from the barnacle encrusted rocky ledge of Bran point eastwards across Ringstead Bay towards White Nothe, Dorset, UK on the Jurassic Coast (3)

 Revision of a post first published 29 April 2009

COPYRIGHT JESSICA WINDER 2011

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