Seafloor pockmarks and gas seepages, northwestern Bay of Fundy, New Brunswick, Canada

Bathymetric images of linear and circular pockmark depressions on the Bay of Fundy seafloor, offshore eastern Canada, are interpreted to have been caused by escaping gas from underlying sediment or bedrock. Shallow interstitial gas within marine sediments restricts seismic reflection imaging (acoustic masking) of sub-bottom units resulting in obscured reflections within seismic profiles, confirming that interstitial gas is present in the underlying units. Pockmark fields are frequent in several bays and shallow coastal areas along the northern coast of the Bay of Fundy. The largest field containing over 10 000 pockmarks occurs in Passamaquoddy Bay, an estuary underlain by igneous and metamorphic bedrock. These features are interpreted to be caused by generation of biogenic methane from the microbial breakdown of organic matter buried within Holocene-age sediments and along the underlying Pleistocene/Holocene unconformity. The unconformity is recorded as a distinctive horizon that represents a time when glacier recession resulted in exposure of parts of the bay to sub-aerial erosion and growth of terrestrial vegetation at locations subsequently submerged by post-glacial transgression. Three areas of potential thermogenic gas occurrence were identified in seismic profiles collected south and east of The Wolves islands, New Brunswick. The underlying bedrock has not yet been precisely mapped, although outliers of Carboniferous-age bedrock that is the major petroleum source in New Brunswick may extend into this area of the Bay of Fundy.

A new secondary ecotope for talitrids: driftwood in the Bay of Fundy

Platorchestia platensis (Amphipoda, Talitridae) was previously known ecologically as a wrack generalist, but here we describe a secondary driftwood ecotope for this species. The trophic dependence of driftwood-acclimated P. platensis on rotting wood was confirmed by successfully culturing it within driftwood, without further addition of food. The stranded driftwood in which P. platensis was found contained gribble burrows (round and of 0.6 to 5 mm diameter). We hypothesize that P. platensis used the empty gribble burrows for interspecific squatting (to gain initial entry to driftwood and for shelter). We found eleven driftwood depositories in a 230 km length of shoreline in Passamaquoddy Bay. The commonest driftwood was of spruce and eastern white cedar. The small marsh at Hartley Cove contained a driftwood depository, where the new driftwood ecotope was discovered. This site was studied temporally to understand how wind and tidal forces might affect import and export of driftwood.

New phytoplankton species in the Bay of Fundy since 1995

Martin, J. L., and LeGresley, M. M. 2008. New phytoplankton species in the Bay of Fundy since 1995. – ICES Journal of Marine Science, 65: 759–764. A monitoring programme was initiated in 1987 to study phytoplankton populations in the Western Isles region of the Bay of Fundy, southwest New Brunswick. Samples are collected weekly from May through October, and monthly during the remaining months, to determine phytoplankton distribution and abundance at Brandy Cove, Lime Kiln Bay, Deadmans Harbour, the Wolves Islands, and mid-Passamaquoddy Bay. Since the programme was initiated, several previously absent or non-indigenous species have been found, suggesting that new species may have been introduced to the area. In order to establish a baseline for species indigenous to Bay of Fundy waters, we have taken a conservative approach and termed species reported for the first time in the Bay of Fundy system since 1995 as “new” species. New species include the following: (dinoflagellates) Alexandrium pseudogonyaulax, Amphidinium carterae, A. sphenoides, Ceratium macroceros, Polykrikos schwartzii, Preperidinium meunieri, Protoperidinium crassipes, and Pyrocystis lunata; (diatoms) Attheya septentrionalis, Attheya longicornis, Chaetoceros radicans, Cylindrotheca gracilis, Grammatophora serpentina, Lithodesmium undulatum, Mediopyxis helysia, Membraneis challengeri, Neodenticula seminae, Odontella sinensis, Proboscia eumorpha, Pseudo-nitzschia subpacifica, Pseudo-nitzschia fraudulenta, and Thalassiosira punctigera.

Sonic tracking of wild cod, Gadus morhua, in an inshore region of the Bay of Fundy: a contribution to understanding the impact of cod farming for wild cod and endangered salmon populations

Sea cage trials of Atlantic cod farming have begun in the Bay of Fundy region. We fitted inshore wild cod (n = 10) captured in the Quoddy region with sonic tags during the late summer of 2004 to provide data on their temporal and spatial residency and habitat usage, with a view to understanding the potential for impact between escaped farmed cod and wild cod and other fish species, particularly Atlantic salmon. Most of the tagged cod remained within a restricted corridor in the inshore zone, occupied deep water (75–130 m) within several kilometres of the release point, and undertook local movements. Three cod undertook more extensive movements; one fish emigrated offshore immediately, and two fish moved as far as 14 km from the release point before returning, 52–54 h later, to the area in which the other cod were located. The mean residence time in the inshore zone was 55 days. In the late autumn, there was a staggered pattern of departure from the coastal zone, although one fish over-wintered in Passamaquoddy Bay. Three of the nine cod that migrated offshore in autumn 2004 returned within a three-week period in May 2005, after a mean absence of 172 days, and reoccupied the inshore region inhabited the previous year. These cod left the region again after a mean residence of 120 days during the spring and summer. The presence of some of the tagged cod in the principal migration corridor for wild salmon smolts during the period of their migration suggests that escapes from cod farms could result in increased predation on salmon smolts from endangered populations.