Bonavista Bay Research Articles

Larvae of the Hermit Crab,Pagurus arcuatus, From the Plankton (Crustacea, Decapoda)

Four Zoeal Stages and the megalopa of the hermit crab, Pagurus arcuatus, Squires, 1964, are described from the plankton and compared with P. acadianus Benedict, 1901, the only other species present in a small inshore area in Bonavista Bay, Newfoundland. Pagurus arcuatus has longer exopods than endopods of antennae in Zoeal Stages I–III, few setae on scaphognathite and medial accessory spine on inner spine of uropodal exopod in Zoea Stage IV, and in the megalopa no median posterior spine on abdominal somite 6 and no postero-lateral spurs on the telson. It has a low posterolateral spine on each side of the soft part of the carapace, also 8 setae at the posterior edge of telson. All these are different from P. acadianus.

Size distributions of bergy bits and growlers calved from deteriorating icebergs

Measurements have been made of the size distributions of ice particles calved from actively deteriorating icebergs in Bonavista Bay, Newfoundland. The populations of bergy bits, growlers, and very small ice pieces show an inverse exponential relationship between water line length and frequency of occurrence. Most of the particles calved are too small to be of significance in the context of ice/structure interaction. On average 13.9 particles in the 5 to 20 m length range were produced per calving event. Only 1.9 of these are greater than 10 m in length.

Diurnal Feeding of Juvenile Cod (Gadus moruha) which Migrate into Shallow Water at Night in Eastern Newfoundland

In Bonavista Bay, Newfoundland, juvenile cod (Gadus morhua) (age-group-0 and -1) were found to move into shallow water at night, where they mostly rested near the bottom. This nocturnal inshore migration was not associated with feeding, as stomach contents data suggested that feeding takes place mainly during the day, with little or no feeding at night. Most prey were planktonic, even in age-group-1 cod. This contrasted with earlier studies in Conception Bay, Newfoundland where age-group-1 cod were mainly obtaining benthic prey. These results suggested that juvenile cod predation on benthic invertebrates was likely to be patchy in space and time. Results are discussed in view of previous knowledge of the dietary and activity patterns of juvenile cod from elsewhere.

Long-Term Observations on Movements of Tagged Male Snow Crabs in Bonavista Bay, Newfoundland

Approximately 10,000 legal-sized male snow crabs Chionoecetes opilio were tagged and released on the commercial fishing grounds of Bonavista Bay between 1979 and 1982 inclusive, The distance that the snow crabs traveled, as determined from 4,255 recaptures, ranged from 0.6 to 74.1 km (mean, 10.7 km; median, 8.5 km). Snow crabs appeared to remain within Bonavista Bay: there was no observed movement to adjacent commercial crab-fishing areas over periods of up to 5 years. The practice of managing the fishery as a discrete unit appears to be warranted.

Erratum: Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland

Erratum: Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland

Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland

High-resolution seismic profiles and core data from Bonavista Bay, northeast Newfoundland, show that the sedimentary package above acoustic basement was deposited during the deglaciation of the Late Wisconsinan ice sheet. During the Late Wisconsinan maximum (~ 20 000 BP), Bonavista Bay was occupied by a grounded ice sheet that extended farther offshore. Deglaciation of the bay was rapid and occurred prior to ~ 13 500 BP during a time of rising sea level. A basal till was deposited beneath the grounded ice, and after lift-off an ice shelf developed over the outer basins where diamicton was deposited. The inner bay gradually deglaciated as the ice margin retreated to the present-day shoreline by ~ 13 000 BP, and fine-grained outwash sediments transported by interflows were rapidly deposited. The inner bay remained under the influence of one or more remnant ice centres until ~ 10 000 BP, with ice positioned on the Bonavista and Gander peninsulas. Normal marine conditions were established in the outer bay by ~ 13 500 BP and in the inner bay and fjords by ~ 10 000 BP.

A nocturnal inshore movement of juvenile cod Gadus morhua L. in eastern Newfoundland

Juvenile cod Gadus morhua L. (aged 1 + and 2 +) were counted, using an underwater scuba transect method, during the day and at night in shallow water at Newman Sound, Bonavista Bay, Newfoundland. They were 16 times more abundant during the night than during the day. Sampling at one site throughout a 24-h period showed that they arrive in shallow water at dusk, and leave again just before dawn. Much searching among algae and in crevices showed that the young cod are not simply hiding in cryptic habitats during the day. The hypothesis that they spend the day in deeper water is presented.

Shell Hardening in Snow Crabs Chionoecetes opilio Tagged in Soft-Shelled Condition

Altogether, 1,591 commercial-sized (≥95 mm carapace width) male snow crabs were tagged and released in soft-shelled condition onto the commercial crab grounds of Bonavista Bay, Newfoundland, during August 1984. Between September and December 1984, 68% of those animals released were recaptured by commercial crab fishermen. Among those crabs recaptured 31–60 d after release, 32.8% had recovered to a hard-shelled condition. The hard-shelled condition increased to 96% for crabs at large for 76–90 d and was virtually 100% for those at large for more than 90 d.

Small-Scale Seasonal Movements of the American Lobster Homarus americanus

Abstract American lobsters Homarus americanus in Bonavista Bay, Newfoundland, observed by scuba divers, moved within a 30-m depth range to deep water in autumn and back to shallow water in spring. During summer, most animals occurred at depths more shallow than the thermocline, which usually lay at 5–10 m. Autumn movements appear related to increased turbulence due to frequent storms and to breakdown of the thermocline. The animals became inactive and remained at depth during winter but returned to shallow water as temperature and activity increased during spring. Received May 12, 1983 Accepted March 19, 1984

Repeated basement reactivation in the northeastern Appalachians

AbstractIn the northeastern Appalachians crystalline, basement outcrops within a y‐shaped belt extending southwest from Bonavista Bay, Newfoundland, to Port aux Basques, and thence via the Cape Breton Highland to near Saint John, New Brunswick. Locally a Precambrian platformal sequence lies on the basement. Stratigraphic and isotopic evidence demonstrate that in the Saint John and northern Cape Breton regions, both basement and cover were remobilized about 600 million years ago, the basement probably for the second time. After deposition of a Cambro‐Ordovician cover, these rocks were again mobilized and intruded in mid‐Ordovician and Devonian time. Evidence for basement reactivation in Newfoundland, although fragmentary, is compatible with a similar history. Much of the basement gneiss is presently exposed in uplifted fault blocks.The observations can be explained in plate tectonic terms if the sedimentary accretion prism collapses during plate convergence, and is pushed onto the craton, which is itself thickened due to compressive stress. Because the edge of the cration is heated, due to thickening of both basement and sedimentary cover, the basement rises due to lowering of density by thermal expansion, and ultimately by partial melting. Depending on relative rates of heating, buoyant rise, and erosion, the process can lead either to a characteristic pattern of linear belts of reactivated basement which display positive gravity and magnetic anomalies, or to a chain of elongate gneiss domes exhibiting gravity lows. Application of the model to the northeastern Appalachians suggests that several continental fragments are present, and that basement rocks have been involved in repeated continental collision and breakup.

Paleomagnetism of diabase dikes from the Bonavista Bay area of northeastern central Newfoundland

Paleomagnetic results are reported for a swarm of diabase dikes from the northeastern Gander Zone of the Newfoundland Appalachians. Sixty-eight cores were collected from 19 dikes cutting the various granites and migmatites from the Bonavista Bay area of Newfoundland. From the earlier structural and Rb/Sr age data available, one can infer an age for the dike swarm of between 400 and 330 Ma. Paleomagnetic studies including alternating field and thermal demagnetizations reveal that the swarm can be divided into two groups: group 1 has a characteristic magnetization of D = 296.6°, I = 82.2° with α95 = 5.8° for N = 14 dikes with the corresponding pole position at 53.9°N, 77.4°W (δp, δm = 11.0°, 11.3°; group 2 has a characteristic magnetization of D = 157.6°, I = 53.9° with α95 = 9.0° for N = 5 dikes with the corresponding pole position at 3.9°S, 35.5°W (δp, δm = 8.8°, 12.6°). One dike's magnetization was found to be reversed relative to the other group 2 dikes. Various magnetic experiments (low- and high-field hysteresis, Curie temperatures, susceptibility variation with temperature, coercivity of remanence, Lowrie–Fuller test) conducted to study the bulk magnetic and remanent magnetic properties of the dike material suggest that their behavior is consistent with multidomain pure magnetite being the dominant magnetic mineral. The group 1 pole position lies close to Newfoundland and is similar to other poles of equivalent age for intrusives from New Brunswick and Newfoundland. Rock units from the southeastern margin of the Iapetus Ocean thus seem to be yielding consistent "high-latitude" poles, a factor that needs to be taken into account in any discussion of the tectonic evolution of the area.

The migration of humpback whales along the northeast coast of Newfoundland

Humpback whales migrate along the northeast coast of Newfoundland in summer. Individuals were identified which moved from St. Vincent's on the south coast to Bonavista Bay on the northeast coast, and from there to southern Labrador. The mean migration rate northward along the northeast coast in summer was estimated to be 1.2° latitude per month, although animals moved through a study area at the end of the Bay de Verde Peninsula at about twice this rate. The animals arriving at Bay de Verde in early July, when humpback densities were higher, were on average larger than those arriving either earlier or later. Over periods of more than 1 day there was no evidence for consistent companionships (other than mothers with their 1st-year calves), and only one animal appeared to have a preferred range within the Bay de Verde study area, although some whales preferentially returned to certain stretches of the coastline in different years.

Determination of Sexual Maturation Stages of Atlantic Salmon (Salmo salar) Captured at Sea

Radioimmunoassay (RIA) of plasma vitellogenin (Vg), estradiol (E2), 11-ketotestosterone (11-keto), and gonadotropin (GtH), together with histological techniques were evaluated for determination of the maturation stage of Atlantic salmon (Salmo salar) at sea.Male salmon had lower plasma Vg, E2, and higher 11-keto levels and could be distinguished from females several months in advance of spawning. Six female salmon were tagged at sea in 1975 in Placentia Bay and samples of blood taken. When the fish were recovered in rivers the lowest plasma Vg value was 396 μg/mL. This formed the basis of a working hypothesis, that fish with Vg values in excess of 396 μg/mL (~5–6 mo before spawning) will spawn in the year of capture. This hypothesis was supported by the Vg values of an additional 19 tagged females recaptured in Newfoundland and mainland rivers and brackish water off mainland rivers in 1976.Significant correlations between stage of gonadal development and plasma Vg, stage of gonadal development and gonadosomatic index (GSI), stage of gonadal development and plasma E2, plasma Vg and plasma E2, GSI and plasma E2, and between plasma Vg and 11-keto values were found for the female fish. The gonadal development of female fish from Bonavista Bay ranged between oil globule stage and secondary yolk stage. All those females which had reached the primary yolk stage would almost certainly mature and may be considered spawners of the year; on this basis 91% of the females were spawners of the year. Based on the minimum plasma Vg values, at sea, for fish which subsequently returned to the rivers, there were 86% spawners of the year among female salmon taken in Bonavista Bay. Based on plasma Vg levels, spawners of the year ranged from essentially zero in Greenland (fish captured in Greenland during August–November are not spawners of the year, except for the very few that spawn in one Greenland river) to 100% for fish caught in several other fisheries.11-Ketotestosterone was higher in the male fish than in the female fish and there was a correlation between GSI and 11-keto for male fish.The plasma GtH content of fish taken in the sea was extremely low as measured by RIA.Key words: salmon, maturation, migration, radioimmunoassay, vitellogenin, estradiol, gonadotropin, 11-ketotestosterone, histology, gonadosomatic index

The Newport granite: its age, geological setting, and implications for the geology of northeastern Newfoundland

The undeformed Newport megacrystic granite of northwestern Bonavista Bay postdates nearly all the other granites in the area, many of which are strongly cataclastic. It also cuts a regional swarm of diabase dikes. The Rb–Sr isochron of 332 ± 42 Ma for the Newport overlaps the 300 ± 18 Ma isochron age of the deformed Lockers Bay megacrystic granite which is cut both by the Newport and the diabase dikes. This indicates that the emplacement of the Lockers Bay pluton, its deformation, and the intrusion of the diabase dikes and the Newport granite all took place in the interval 290–320 Ma, that is in late Carboniferous times. Major movements along the Dover Fault line, which truncates the Newport in the southeast, probably occurred subsequent to this interval.

On the plutonic evolution of the Wesleyville area, Bonavista Bay, Newfoundland

The Wesleyville area is composed of polydeformed gneisses and migmatites cut by a series of granitic plutons and dike suites. Four major episodes of igneous activity are recognized as follows: (1) the emplacement of the garnetiferous Powder Hill Leucogranite, marking the first event; (2) the emplacement of the large megacrystic granites of Deadman's Bay and Cape Freels; (3) development of a suite of diabase dikes; and finally, (4) the emplacement of the Newport pluton, a megacrystic granite almost identical in lithology and chemistry to the earlier ones.The country rocks were affected by five deformation episodes, of which the first two and a regional migmatization pre-dated the Powder Hill pluton. These rocks were then deformed by a third episode, and the last two events post-dated all but the diabase dikes and the Newport pluton. A 400 ± 5 m.y. whole-rock isochron date on the Cape Freels indicates that it is Devonian. This also provides a lower age limit on a late fault that apparently truncates the Newport pluton, and which locally forms the junction between the Avalon and Gander Zones.

The Dover Fault: Western Boundary of the Avalon Zone in Northeastern Newfoundland

Basement rocks of the Hare Bay Gneiss Complex and associated granitic intrusive rocks on the western side of Bonavista Bay, northeastern Newfoundland, are separated from clastic sedimentary and volcanic rocks of the Avalon Zone (Love Cove and Musgravetown Groups) by a 300–500 m wide mylonite zone called the Dover Fault. The Dover Fault juxtaposes rocks of contrasting lithology and metamorphic, intrusive, and structural histories and represents the boundary between the Gander Zone and the Avalon Zone of the Newfoundland Appalachian System. Structural relationships across the fault zone indicate that early movement on the Dover Fault was contemporaneous with deformation of the Love Cove Group. Relationships elsewhere in the Avalon Zone indicate that the Love Cove Group was deformed in Hadrynian time and hence the Dover Fault was probably initiated as an Hadrynian structural feature, probably related to Hadrynian orogeny on the eastern side of the Appalachian system.

Food, Feeding, and Condition of Lobsters, Homarus americanus, Throughout the Seasonal Cycle in Bonavista Bay, Newfoundland

The rock crab, Cancer irroratus, and spider crab, Hyas araneus, made up about 50% of the food of lobsters in Bonavista Bay, Nfld. The sea urchin, Strongylocentrotus dröbachiensis, several species of molluscs, and several species of sea stars made up 7.1, 10.9, and 10%, respectively. The remainder was mainly a variety of bottom invertebrates but fish and seaweeds were also fairly common. There was a change to a slightly more calcium-rich diet during the molting season. A rapid increase in feeding activity during the summer coincided with increasing temperatures, but despite decreasing temperatures during the fall, feeding activity remained high. The feeding index for females remained high longer into the winter than for males. Physiological condition was directly related to the molting cycle. Premolt condition was very high, postmolt very low, and recovery to the intermolt condition was attained about [Formula: see text] months after the peak molting period.

Infection of the giant scallop Placopecten magellanicus from Newfoundland with an endozoic alga

Some aspects of the relationship between a unicellular alga and the giant scallop, Placopecten magellanicus, are presented. The relationship is confined to the shallow water populations of the pectinid species (Port au Port Bay, St. Mary's Bay, Bonavista Bay, Newfoundland). Scallops from deeper water, including Georges Bank, are particularly free of the alga. It is believed that the alga's requirements for light prevents its establishment beyond a certain depth. The larger, older scallops, especially those with damaged or deformed shells, are particularly susceptible to the alga. Infections usually involve the peripheral mantle tissue, but may extend into the distal end of the gonad and the bases of the posterior adductor muscle. When present in large numbers, the alga has an adverse effect on its host; however, there is no evidence of parasitic castration.

Eastern Extension of the Range of the Blackspotted Stickleback, Gasterosteus wheatlandi, in Newfoundland

Blackspotted sticklebacks, Gasterosteus wheatlandi, were collected at Northeast Arm, Bonavista Bay, Newfoundland (48°39′N, 53°55′W). This is the most easterly occurrence reported for Canadian waters.

Report on the larva, eggs, and egg mass of Rossia sp. (Decapoda, Cephalopoda) from Bonavista Bay, Newfoundland

For the first time, larvae and egg masses of decapod cephalopods are here reported from the waters of Newfoundland and Labrador. The specimens in question are from a depth of 180 fathoms in Bonavista Bay in the north of insular Newfoundland. One larva and eight eggs of extremely large size were found in a mass composed of fibrous and spongy components. The decapod is assigned to the genus Rossia. The egg mass was found to incorporate living tissue of the demospongid Isodictya palmata (Lamarck).