Minas Channel Research Articles

Tidal power generation in the glaciated, macrotidal Minas Scour Trough, Bay of Fundy, Atlantic Canada

The configuration of the Bay of Fundy results in large tides (up to 17 m) which give rise to strong currents (Fig. 1d). Harnessing these currents to generate electricity has been the focus of engineering schemes dating from 1910. Fundy tidal power generation has garnered attention periodically throughout the twentieth century (Gordon et al. 2014). The seabed and water column conditions in the Minas Scour Trough at the NE head of the Bay of Fundy (Fig. 1a, d) are now the subject of engineering studies to characterize the site for electricity generation. Test installations have been deployed on the seabed, the subsea cable to collect and transmit power to the electrical grid on land has been laid and future infrastructure instalments are planned. Fig. 1. Multibeam swath bathymetry and geophysical profile of the main Minas Scour Trough, Bay of Fundy. ( a ) Sun-illuminated multibeam-bathymetric image showing the tidal scour system developed in, from west to east, Minas Channel, Minas Passage and Minas Basin. Inset interpretation shows the extent of the scour trough. Acquisition system Kongsberg EM1000. Frequency 95 kHz. Grid-cell size 5 m. ( b ) Seismic-reflection profile in Minas Channel showing eroded glacimarine sediments and exposed bedrock cropping out in Minas Scour Trough. VE×67. Acquisition …

Distribution of the non-indigenous colonial ascidian Didemnum vexillum (Kott, 2002) in the Bay of Fundy and on offshore banks, eastern Canada

The invasive colonial ascidian Didemnum vexillum (Kott, 2002) was initially discovered in the fall of 2013 near Parrsboro, Nova Scotia. A rapid response survey was conducted in April 2014 to confirm the presence of the species and to determine its distribution near the original detection site. Subsequent surveys between May and August 2014 examined the dredge contents collected during sea scallop stock assessment surveys on German Bank, northern Browns Bank, eastern Georges Bank and in the Bay of Fundy region. The presence of D. vexillum was confirmed at 22 of 30 stations sampled in four areas of the Minas Basin and Minas Channel region in the northern Bay of Fundy during the rapid response survey. The scallop surveys confirmed the presence of D. vexillum at 9 of 829 stations sampled in the Bay of Fundy region, including 7 in the Minas Basin, 1 off Digby Gut and another off the coast of Yarmouth. Due to the presence of a native species, D. albidum, in the region, a PCR assay was developed to distinguish D. vexillum from all other species in the region. Once the PCR assay was validated this assay was used to confirm all positive identifications in this study. Colonies overgrew rocks, bivalve shells and seaweeds or were retrieved as large dislodged fragments. They were in an overwintering state in April, but healthy, and observed to grow into dense mats in summer. In other regions of the world, D. vexillum has been reported to foul shellfish and aquaculture gear, smother benthic organisms such as the sea scallop (Placopecten magellanicus), and overgrow substrates, suggesting this new colonial invasive ascidian poses a potential threat to Eastern Canada aquaculture and commercial benthic fisheries.

Anatomy of the tidal scour system at Minas Passage, Bay of Fundy, Canada

Strong currents have eroded thick Quaternary sediments to create a scour trough at Minas Passage, in the Bay of Fundy, Canada, site of Earth's largest tides. We describe this trough in the context of a larger system that comprises a range of elements, viz: 1) Scour troughs extending 170m below mean sea level are incised into thick glaciomarine sediments and have exhumed bedrock over wide areas. The flanking uneroded terrain has low relief and a winnowed surface. 2) Sets of sand banner banks off Cape D'Or and Cape Chignecto. 3) The atypical set of banner banks at Cape Split, consisting of the Scots Bay dune field and its counterpart, a large gravel bank trapped in the Minas Passage scour trough. 4) Low-relief banks with sand ribbons and barchan dunes alongside some banner banks, and termed ‘shadow banks’. 5) A large (0.8km3) sediment drift at the entrance to Minas Channel (without large bedforms). The location of troughs and banks can be correlated with tidal-current patterns: trenches are located in regions of very strong bi-directional currents; banner banks near headland-sited tidal gyres; shadow banks in areas of maximum mean bottom stress asymmetry; and the sediment drift at the entrance to Minas Channel in an area of weak bottom stress at all stages of the tides. Previous work has argued that the scour system formed after 3400 14Cyrs BP (radiocarbon years before present) following collapse of a barrier system across Minas Passage. We speculate that formation of the scour trough system may have released vast quantities of sediment that have not been accounted for in previous sediment budgets, and that much of this released sediment has been sequestered in the late-Holocene salt marshes at the head of the Bay of Fundy.

Tidally-induced sediment transport patterns in the upper Bay of Fundy: A numerical study

The Minas Basin, the eastern end of the Bay of Fundy, is well known for its high tide ranges and strong tidal currents, which can be exploited to extract electricity power. The properties of the tidally-induced sediment transport in the Minas Basin, where significant changes in tidal processes may occur due to a recently proposed tidal power project, have been studied with a three-dimensional hydrodynamic model, an empirical bed load sediment transport model and surface sediment concentrations derived from the remotely-sensed images. The hydrodynamic model was evaluated against independent observational data, which include tidal elevation, tidal current (in the full water column and bottom layer), residual current profile and tidal asymmetry indicators. The evaluation shows that the model is in good agreement with the observations. The sediment transport includes two components, bed load and suspended particulate load. The bed load is calculated using the modelled bottom shear stress and the observed grain size data. The estimated features of bed load transport roughly agree with the observed patterns of the erosion and deposition in the Minas Basin and Cobequid Bay. The transport of the suspended load is estimated using the modelled velocity fields and the surface sediment concentration derived from remote-sensing images. The comparisons between the modelled results and the limited observations illustrate that the observed directions of suspended sediment transport are basically reproduced by the model. The modelled net suspended sediment input into the Minas Basin through Minas Passage is 2.4×10 6 m 3 yr −1, which is comparable to the observed value of 1.6×10 6 m 3 yr −1. The variations of the bed load and the suspended load in space and time are also presented. The total net transport, defined as the mean value of the sum of bed and suspended load transports during the tidal cycle, shows strong spatial variability. The magnitude of the transport flux ranges from 0.1 to 0.2 kg m −1 s −1 in Minas Channel and Minas Passage, 0.1 kg m −1 s −1 in Cobequid Bay, to 0.01 kg m −1 s −1 in the central Minas Basin and Southern Bight. In Minas Channel, the sediment transport follows the structure of the tidal residual circulation, which features a large anticlockwise gyre. The sediment in Minas Passage moves eastward and deposits into the central Minas Basin. However, the sediment from the eastern part of the Basin moves westward and deposits in the central Minas Basin as well. In the Cobequid Bay, sediment moves eastward and deposits in the upper bay.

Simulation-based evaluation of tidal current power output characteristics

Tidal current is considered to be one of the promising alternative green energy resources. This paper introduces a simulation based methodology to evaluate tidal current power output characteristics, including capacity factor, and power production variability patterns. Power variability analysis is crucial to grid integration systems design. The proposed methodology is applied to the well known Minas Channel in the Bay of Fundy (Atlantic Canada).

Metal contaminants for modelling lobster ( Homarus americanus) migration patterns in the Inner Bay of Fundy, Atlantic Canada

A method, which uses metal compositions in lobster digestive glands as natural environmental tags, has been developed to trace lobster movements. Lobsters were collected from three selected sites, Minas Channel, Minas Basin, and Cobequid Bay, Inner Bay of Fundy, New Brunswick, Canada, that were known to be contaminated with Cu. Five metal variables (Ag, Cd, Cu, Mn and Zn) were processed for principal component analysis (PCA). Metal concentration and burden models were investigated and PCA was able to differentiate lobsters from the respective catch sites. The method was applied to investigate the May and June lobsters collected at the three sites to determine the migration rate during this period of the fishing season. The results show a high level of mixing at Minas Basin and Cobequid Bay in June, and lobster movement inward toward the inner reaches of the bay, with very limited movement outward from the inner bay.

Tide-Induced Residual Current—Verification of a Numerical Model

Abstract In Tee (1976), tide-induced residual currents in the Minas Channel and Minas Basin were studied with a two-dimensional nonlinear numerical tidal model. It was shown that the model could reproduce well the observations obtained in 1960 and 1965. In this paper, further observations obtained in 1974 are presented. The analyzed results confirm the calculated tidal and residual currents, and the mechanic that was suggested for the generation of the residual currents. Calculated and experimental results show that the maximum M2 tidal current occurs earlier in the sheltered arms.

Theory of the Exploitation of Tidal Energy and Its Application to the Bay of Fundy

Considerable progress has been made in the understanding of the concepts underlying the exploitation of tidal energy during the last 20 years; this progress has culminated in the actual construction of a tidal plant at the mouth of the Rance River near St. Malo, France. Since the Bay of Fundy is one of the largest reservoirs of tidal energy in the world, the theory of exploitation of tidal energy has been reviewed with a view to its application to the Bay of Fundy.The rate of change of the energy contained in an oscillating mass of water in a basin on a rotating earth can be written out using the equations of hydrodynamics. The concept of power transfer arises immediately, which enables one to follow the transit of power from one part of the basin to another. This makes it possible to establish a balance of the power present in the basin.Only the potential energy present in the tide can be profitably exploited, and it is obtained by enclosing part of the basin by a dam in which some turbines and pumps are imbedded, as well as some complementary sluices. The emptying and filling of the enclosed part of the basin through the turbines during the fall and rise of the sea leads to the production of energy. The upper bounds of the energy available in this way can be easily established and it can also be readily shown that the use of pumps increases the amount of energy available. The actual amount of energy drawn from the reservoir is limited by the smaller range of the tide inside the reservoir and the efficiency of the turbines. The timing and duration of the various operations involved in the operation of a tidal plant, pumping, generating power, opening or closing the sluices, waiting for a head to develop, can be studied quantitatively.For this purpose the type and number of fundamental operations are carefully studied and accurate definitions are given of them, permitting calculations on a number of possible sequences of operations up to 25 tidal periods. The number of possible sequences is very large and it is not possible to study all of these sequences individually.Under some circumstances a given sequence of operations for the actual times of starting and stopping the turbines, starting and stopping the pumps, opening and closing the sluices, waiting for a head, and the changes of level inside the reservoir can be calculated with the help of the calculus of variations. For instance, these quantities yield to systematic calculation if the plant is operated with the purpose of producing the maximum amount of energy. The calculus of variations, however, cannot help directly when other modes of operation are considered, such as operating the plant in such a way as to supply power only during peak demand.The response of the basin to the oscillating ocean will be altered after the construction of the reservoir needed for the operation of the tidal plant. This modification may be important when the plant draws considerable amounts of energy from the tide.With the help of the concepts developed it becomes an easy task to make a balance sheet for the tidal power present in the Bay of Fundy, restricting ourselves to M2, the main lunar semidiurnal constituent that is representative of average conditions. Many sites in the Bay of Fundy are found to be suitable for the generation of energy; some involve relatively simple engineering and yield modest amounts of energy such as the Digby site; others, such as the Minas Channel site, could yield very considerable amounts of energy but the engineering difficulties associated with their construction might prove prohibitive.

Origin of the Bay of Fundy, an interpretation from sub-bottom profiles

It has long been debated whether the Bay of Fundy is derived from glacial or fluvial erosion of the underlying Acadian Triassic Basin. The recent acquisition of over 1,100 kilometers of sub-bottom profiles provides considerable data pertinent to this problem. Features indicative of glacial erosion are widespread. The bedrock floor of the Bay, generally mantled with ten m or less of drift, is exceedingly flat, with gradients of two meters per kilometer and less. Where freshly exposed by tidal scour on the shore, this surface is a striated glacial pavement. Longitudinal submarine troughs on the floor of the Minas Channel, Chignecto Bay, and at the mouth of the Bay of Fundy are still blocked with glacial drift, and were formed in part by longitudinal ice movement. However, the orientation of striae at the Bay's margins and of submarine morainal segments and boulder fields suggest transverse movements. A drift-buried, bedrock river channel is displaced south of the Bay's bathymetric axis; if an ice margin feature, it outlines a former ice lobe that extended southeast across the Bay from New Brunswick. The discovery of a Lower Cretaceous valley filling marginal to the Bay suggests that the present drainage system of Nova Scotia may be an exhumed Mesozoic system. If so, the Bay of Fundy, while strongly modified in the Pleistocene, was probably initiated by Mesozoic subaerial erosion.

A Subtidal Sandbody in the Minas Channel, Eastern Bay of Fundy

A Subtidal Sandbody in the Minas Channel, Eastern Bay of Fundy

Zooplankton of the Inner Bay of Fundy

The inner Bay of Fundy and Minas Channel are practically devoid of locally produced zooplankton. The few plankters present are either estuarine species from Minas Basin and Chignecto Bay or immigrants from the Gulf of Maine. The former (Acartia tonsa, Eurytemora herdmani, Centropages hamatus, Pseudodiaptomus coronatus and Canuella canadensis) are abundant inland with shallowing and heavy river discharge. The latter (Calanus finmarchicus, Sagitta elegans, Pseudocalanus minutus, Oithona similis and Parafavella gigantea) all show a similar distribution, being abundant in the mouth of the Bay, but declining greatly going inward. Also, Calanus specimens from the inner Bay have little or no fat, which indicates a lack of food there.The extreme paucity of all zooplankton in Minas Channel is apparently caused by heavy and deep turbulence, which prevents development of phytoplankton on which the animals depend for food.

Shubenacadie Salmon

Salmon from the fishery in the brackish outflow of the Shubenacadie River through its estuary and Cobequid Bay consist mainly of 3-year-old grilse that are much larger than comparable fish taken in Grand Lake at the head of the River, and somewhat larger than comparable fish taken in Minas Channel through which these waters are connected with the Bay of Fundy. These salmon are found to be peculiar also in age composition and thus to form a separate population. That they are large for their age is attributed to exceptionally good estuarial conditions for production of zooplankton and for feeding.With low rainfall these fish are caught mainly far in the outflow and with high rainfall far out. Their numbers fluctuate greatly for unknown reasons except that utter failure of the grilse in 1951 has been found related to lack of rain when they should have been spawned.

Movements and Decline of Large Quoddy Herring

Development, beginning in 1876, of heavy fishing for "sardines", the yearling herring available in and near Passamaquoddy Bay between New Brunswick and Maine, was followed by decrease in numbers of older fish. The very local and very fat "Quoddy River" herring disappeared promptly. The immense accumulated stock of large spawning herring lasted ten years or more after recruitment was thus greatly reduced. This stock was being coincidently shifted from the Quoddy region, apparently owing to reduced rainfall.The normal seasonal shifting of these fish is between the outer side of Grand Manan Island in summer and near the mainland in winter. In midsummer of 1877, their numbers at Grand Manan began to diminish and for four years remained very low. They were as abundant as ever in winter near the mainland, but farther from shore and more numerous eastward. They appeared inside the Reversing Falls of the Saint John River, whose outflow goes to Grand Manan, in all four years of their scarcity at Grand Manan. Large herring appeared in unexampled numbers at Quaco, east of Saint John, from 1878 to 1881 and then declined. A movement across the Bay to Nova Scotia became evident by a marked rise in Annapolis County in 1881, and, farther in, in Kings County in 1882, in each case lasting for four years and not going beyond the mouth of Minas Channel. These fish seemed to make the circuit of the Bay, affecting catches at its head and on to the New Brunswick side, with return to the Saint John outflow by 1884. Farther out, other lots reached the Nova Scotian coast from Digby to Cape Sable in 1881, remained high for four years and then declined. By 1891, catches everywhere were down to a very low level, indicating exhaustion of the stock.