Pigeon Bay Research Articles

Mixed diatom floras in sedimentary deposits from the 2016 Kaikōura Tsunami at Little Pigeon Bay, Aotearoa-New Zealand

Abstract This study records the diatom flora from sedimentary deposits found within a coastal cottage, following the November 2016 Kaikōura earthquake and tsunami at Little Pigeon Bay, Banks Peninsula, Aotearoa-New Zealand. Unlike previous studies of diatoms from modern tsunami deposits, the sediments in this study were isolated from any previous (and subsequent) reworking of sediments. The diatom flora (n = 117 taxa) are dominated by benthic and planktonic lifeforms with preferences for marine (28%), brackish-marine (25%), fresh-brackish (19%) and fresh-water (17%) conditions. The higher abundances of benthic marine and brackish-marine diatoms are attributed to direct in-washing and reworking of open ocean-water with sandy marine sediments from the sub-tidal and inter-tidal zones. Comparatively high percentage counts of benthic fresh-brackish and freshwater diatom taxa also indicate significant freshwater sources and sediments from the stream and land adjacent to the cottage. Fractured and damaged diatom frustules within the flora, including broken sponge spicules, emphasise dynamic processes of reworking, abrasion and erosion during incoming and outgoing tsunami waves. Likelihood-based ordination analysis of the diatom flora indicates statistical differences between the flora in the back area of the cottage and the centre and front areas which we attribute primarily to the influence of different waves that inundated the cottage from the seaward and landward directions. Such a record affirms a highly mixed diatom flora from multiple sources and habitats. It also offers a first modern analogue from Aotearoa-New Zealand to assist future assessments of multi-proxy-based records of past tsunami events preserved in the geological record.

Numerical modelling of flow in Little Pigeon Bay due to the 2016 Kaikoura tsunami

The magnitude 7.8 Kaikoura earthquake on the north-eastern coast of South Island, New Zealand induced a tsunami, which affected many north-facing bays in Banks Peninsula. The V-shaped Little Pigeon Bay experienced pronounced inundation compared to adjacent bays, causing heavy damage to a cottage at the head of the bay. In order to investigate the characteristics of the tsunami flow in the bay, a numerical model based on nonlinear shallow water theory was established, using tidal levels from the neighbouring Sumner sea level gauge. Three incident wave angles were tested, ranging from due north to 30° east of north. The simulated maximum run-up heights were validated with surveyed results. For all the wave directions, a resonance with a period of 6.3 min was found from 50 to 100 min in the simulation. Based on the physical dimensions of Little Pigeon Bay, idealised models were set-up to analyse the influence of V-shaped embayment on maximum water level, maximum velocity and maximum momentum flux. Bays with sand bars of different crest heights were also investigated. A sand bar with a relatively low crest height (dw/d≥0.5) did not significantly reduce the maximum velocity and the maximum momentum flux.

Sedimentary and geochemical signature of the 2016 Kaikōura Tsunami at Little Pigeon Bay: A depositional benchmark for the Banks Peninsula region, New Zealand

The 14 November 2016 Kaikōura Tsunami inundated Little Pigeon Bay in Banks Peninsula, New Zealand, and left a distinct sedimentary deposit, on the ground and within the cottage near the shore. Sedimentary (grain size) and geochemical (electrical conductivity and X-Ray Fluorescence) analyses on samples collected over successive field campaigns are used to characterize the deposits. Sediment distribution observed in the cottage in combination with flow direction indicators suggests that sediment and debris laid down within the building were predominantly the result of a single wave that had been channeled up the stream bed rather than from offshore. Salinity data indicated that the maximum tsunami-wetted and/or seawater-sprayed area extended 12.5 m farther inland than the maximum inundation distance inferred from the debris line observed a few days after the event. In addition, the salinity signature was short-lived. An overall inland waning of tsunami energy was indicated by the mean grain size and portable X-Ray Fluorescence elemental results. ITRAX data collected from three cores along an inland transect indicated a distinct elevated elemental signature at the surfaces of the cores, with an associated increase in magnetic susceptibility. Comparable signatures were also identified within subsurface stratigraphic sequences, and likely represent older tsunamis known to have inundated this bay as well as adjacent bays in Banks Peninsula. The sedimentary and geochemical signatures of the 2016 Kaikōura Tsunami at Little Pigeon Bay provide a modern benchmark that can be used to identify older tsunami deposits in the Banks Peninsula region.

Effects of Inundation by the 14th November, 2016 Kaikōura Tsunami on Banks Peninsula, Canterbury, New Zealand

At 12:02:56 a.m. Monday, November 14 2016 NZDT (11:02:56 a.m., November 13 2016 UTC) a magnitude 7.8 earthquake struck near Kaikōura on the north-eastern coast of the South Island of New Zealand. This earthquake caused a tsunami along New Zealand’s east coast that was recorded on a number of sea level gauges. Outside of the Kaikōura region, north facing bays along Banks Peninsula were most affected by the tsunami. Of these, Little Pigeon Bay experienced extensive inundation and an unoccupied cottage was destroyed by the wave run-up. We report on the inundation extent and (inferred) flow directions at Little Pigeon Bay, including a study on temporal changes in the field evidence of this inundation. Preliminary modelling results indicate that the waves may have excited resonance in the bay. We also present results from inundation surveys of nearby, north-facing bays on Banks Peninsula. The excitation of resonance in Little Pigeon Bay provides an explanation for the more severe inundation and damage there in comparison to these nearby bays.

Spatial Modeling and Habitat Quantification for Two Diadromous Fish in New Zealand Streams: A GIS-Based Approach with Application for Conservation Management

We developed logistic regression models from data on biotic and abiotic variables for 172 sites on Banks Peninsula, New Zealand, to predict the probability of occurrence of two diadromous fish, banded kokopu (Galaxias fasciatus) and koaro (G. brevipinnis). Banded kokopu occurrence was positively associated with small streams and low-intensity land uses (e.g., sheep grazing or forested), whereas intensive land uses (e.g., mixed sheep and cattle farming) and lack of riparian forest cover impacted negatively on occurrence at sampled sites. Also, if forests were positioned predominantly in lowland areas, banded kokopu occurrence declined with increasing distance to stream mouth. Koaro occurrence was positively influenced by catchment forest cover, high stream altitudes, and areas of no farming activity or mixed land uses. Intensive land uses, distance to stream mouth, and presence of banded kokopu negatively influenced koaro occupancy of stream reaches. Banded kokopu and koaro presence was predicted in 86.0% and 83.7% agreement, respectively, with field observations. We used the models to quantify the amount of stream reaches that would be of good, moderate, and poor quality, based on the probability of occurrences of the fish being greater than 0.75, between 0.75 and 0.5, or less than 0.5, respectively. Hindcasting using historical data on vegetation cover undertaken for one catchment, Pigeon Bay, showed they would have occupied most of the waterway before anthropogenic modification. We also modeled potential future scenarios to project potential fish distribution.

The Sinclairs of Pigeon Bay and the Romantic 'Prehistory' of the Robinsons of Ni'ihau

Francis and Elizabeth Sinclair and their six children migrated from Scotland to New Zealand in 1840. Francis died there in 1846 and in 1863 Elizabeth resettled her, by then expanded, family in Hawai'i. There they bought the island of Ni'ihau and prospered as ranchers and planters, especially after the 1880s under the family name of Robinson. The early history of the family, up to the 1860s, has been often told, but never completely and often inaccurately, and is contained in two distinct historiographic traditions. This essay attempts to set the record straight by providing an extensive body of detailed, accurate information about the Sinclairs, and to discuss these two traditions. The older and more reliable New Zealand one presents the Sinclairs as hard-working pioneer settlers. The Hawai'ian tradition, in contrast, deriving from an oral record passed on by Francis and Elizabeth's daughter Anne, was dominated by elements of 'family romance'. It presented Francis as an heroic naval captain in the Napoleonic campaigns, making him a mythical ancestor befitting a family that had risen in the world. A more matter-of-fact treatment, though, has prevailed since 1988.

Physical volcanology of Miocene basaltic pyroclastic deposits at Pigeon Bay: Remnants of flank scoria cones of Akaroa volcano, Banks Peninsula, New Zealand

Coastal exposures of four lithified pyroclastic units at Pigeon Bay on Banks Peninsula in Canterbury, New Zealand, record flank explosive activity at the Miocene Akaroa volcano. These eroded units are the surface expression of lateral dike injections of hawaiite magma from a central conduit beneath the Akaroa lava shield. The form of the deposits was severely modified by erosion before burial within the volcanic pile and during exhumation. Four lithofacies are proposed, based on the size and shape of clasts and inferred degree of welding: (1) ash‐rich deposits; (2) non‐flattened scoria deposits; (3) mixed scoria deposits; and (4) densely welded scoria deposits. Spatial relationships between lithofacies, steep primary dips, and rapid changes in thickness and grainsize of the beds enable us to infer that the deposits are the eroded remnants of Hawaiian and Strombolian cones. Within the deposits, variations in clast shape and size reflect subtle variations in the processes of fragmentation, in turn controlled by the size and rise rate of bursting gas bubbles. Different degrees of welding reflect local variation in accumulation rates and clast temperature on deposition (in turn partially dependent on residence time in the vent, distance from vent to point of deposition, and clast size).

Distribution, upstream migration and habitat selection of maturing lampreys, Geotria australis, in Pigeon Bay Stream, New Zealand

Adult lampreys, Geotria australis, began to enter Pigeon Bay Stream just before 7 August 1992. Lampreys moved upstream more or less en masse, because adults were found immediately above the tidal limit in August but at the mouths of headwater streams in late October. Capture rates of adult lampreys in fyke-nets were irregular and appeared to reflect the movement of the fish through stream sections as upstream migration occurred. The daily distance travelled by lampreys individually equipped with radio transmitters declined from a high of 87.8 m to 0 m between August and November. Lampreys typically selected the spaces formed under boulders, usually 25 cm in diameter, at the bottom of riffles and at the upstream ends of pools. With only one exception, lampreys were never seen above the surface of the substratum. Movement occurred only at night and at the onset of freshes. Even though upstream movement had ceased for some two to four weeks, lampreys had not spawned and gonads remained far from mature by 30 November 1992.

Factors Contributing to Development of Fragilaria Crontonensis Kitton Pulses in Pigeon Bay Waters of Western Lake Erie

In recent years, anomalous, large, summer Fragilaria crotonensis pulses have been reported from Pigeon Bay. The purpose of this study was to identify the factors which contribute to these pulses, based on experiments designed to investigate the effects of nutrients and the interaction of light and nutrients on growth, field monitoring, and a review of published studies. It was found that summer not only provides optimal water temperatures for F. crotonensis growth, but peak incident solar radiation and water transparency. It is hypothesized that F. crotonensis pulses during summer are dependent upon three major factors: 1) adequate supplies of nutrients (silica and phosphorus); 2) the presence of slight thermal stratification with concomitant wind velocities sufficient to keep cells circulating in the surface mixed layer; and, 3) the presence of low turbidities with concomitant irradiance sufficient for growth. Once such physicochemical conditions exist, it appears that F. crotonensis can grow rapidly (because it is adapted to low light and is a superior exploitative competitor for phosphorus and silica) and achieve densities as high as 950,000 cells L −1. Such pulses may be terminated by lack of wind (which allows cells to sink out of the photic zone), high wind velocities (which increase turbidity and decrease light penetration), or depletion of nutrients. Fragilaria crotonensis is probably not affected by zooplankton grazing because of its large size and chain-forming morphology. An order of magnitude increase in summer nitrogen:phosphorus ratios in Pigeon Bay since the late 1960s may have provided a more optimal environment for F. crotonensis growth in recent years.

Evidence for the Origin of the Hybrid Cliff Fern, Woodsia x Abbeae (Aspleniaceae: Athyrioideae)

After its original description as Woodsia oregana (cathcartiana) x W. ilvensis, W. x abbeae has been interpreted by all authors as the hybrid between W. ilvensis and W. scopulina, on the basis of its scopulina-like hairs, which are absent in W. ilvensis and W. oregana. Evidence is presented here that the form of the pinnae, glands, indusial segments and sorus, and the chromosome number, support the original interpretation of W. ilvensis x oregana. Woodsia x abbeae Butters, a hybrid cliff fern, is found on cliffs and talus slopes in the region of the northern Great Lakes. Although one par- ent is clearly W. ilvensis (L.) R. Br., a problem exists with regard to the identification of its other parent. The description by Butters (1941) as the hybrid W. cathcartiana Robinson x W. ilvensis, was based on plants collected by L. B. and E. C. Abbe, on the north side of Pigeon Bay, Thunder Bay District, Ontario, Canada. In his account, Butters described characters of W. ilvensis and W. cathcartiana to be found in the hybrid, and stated that in none of the hybrid plants is there any suggestion of W. scopulina D. Eaton. All three species occur in the Thun- der Bay area and in northeastern Minnesota where the hybrid had been found. Woodsia cathcartiana was considered by Brown

The Influence of Light and Temperature on Growth and Photosynthesis ofFragilaria crotonensisKitton

ABSTRACT An axenic clone of Fragilaria crotonensis was isolated from Lake Erie to quantitatively measure its growth and photosynthetic rates under different light and temperature regimes in the laboratory. Maximum growth (0.54 doublings day−1) and photosynthetic (3.7 mg C 10−9 cells h−1) rates were highest at 23 and 17°C and decreased with decreasing temperature (i.e. 11 and 5°C). Even though temperatures of 11 and 5°C are suboptimal for growth of F. crotonensis, they still resulted in 68 and 31%, respectively, of maximum growth rates at 23 and 17°C. Field data show that the F. crotonensis population in Pigeon Bay withstands an annual temperature variation of greater than 20°C and that at 5°c it achieves densities as high as 25% of maximum summer density. These laboratory and field data give strong support that F. crotonensis is eurythermal. The onset of light saturation of both growth and photosynthesis of F. crotonensis occurred at fairly low irradiances, suggesting that it is adaptable to a low light environment.

Seasonal Variation of Nutrient Limitation in Western Lake Erie

Monthly nutrient enrichment experiments were performed from April through October, 1983, to identify growth limiting nutrients of natural phytoplankton assemblages collected from a station in the Pigeon Bay waters off the north shore of Lake Erie's western basin. Data from these experiments suggest that silica was the major limiting nutrient in April, phosphorus was the major limiting nutrient in May-September, and trace metals were limiting in October. These results show that nutrient enrichment experiments should be performed often enough to account for seasonal changes in the physicochemical environment as well as seasonal succession in phytoplankton. The conclusion that phosphorus was the major limiting nutrient in summer is different from the conclusions of the late 1960s and early 1970s that nitrogen was the major limiting nutrient in the summer in the western basin and suggests a possible shift from nitrogen to phosphorus limitation. Pigeon Bay nutrient trend data show that summer nitrate:soluble reactive phosphorus ratios have increased from approximately 4 in the late 1960s to over 40 in the late 1970s and early 1980s, corroborating that a shift has probably occurred. This shift in nutrient limitation is probably due to reduced bioavailable phosphorus loadings and increased nitrate loadings to the western basin. The southern portion of the western basin is physicochemically different from the northern portion and may not have responded in the same manner.