Crossing the front: contrasting storm-forced dispersal dynamics revealed by biological, geological and genetic analysis of beach-cast kelp

The subtropical front (STF) generally represents a substantial oceanographic barrier to dispersal between cold-sub-Antarctic and warm-temperate water masses. Recent studies have suggested that storm events can drastically influence marine dispersal and patterns. Here we analyse biological and geological dispersal driven by two major, contrasting storm events in southern New Zealand, 2017. We integrate biological and physical data to show that a severe southerly system in July 2017 disrupted this barrier by promoting movement of substantial numbers of southern sub-Antarctic Durvillaea kelp rafts across the STF, to make landfall in mainland NZ. By contrast, a less intense easterly storm (Cyclone Cook, April 2017) resulted in more moderate dispersal distances, with minimal dispersal between the sub-Antarctic and mainland New Zealand. These quantitative analyses of approximately 200 freshly beach-cast kelp specimens indicate that storm intensity and wind direction can strongly influence marine dispersal and landfall outcomes.

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Genetic analysis of a documented population bottleneck: introduced Bennett's wallabies (Macropus rufogriseus rufogriseus) in New Zealand

Molecular Ecology ◽

10.1046/j.1365-294x.2000.00922.x ◽

2000 ◽

Vol 9 (6) ◽

pp. 753-763 ◽

Cited By ~ 43

Author(s):

S. L. Le Page ◽

R. A. Livermore ◽

D. W. Cooper ◽

A. C. Taylor

Keyword(s):

New Zealand ◽

Genetic Analysis ◽

Population Bottleneck

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Causes of mortality in stranded Common Dolphin (Delphinus sp.) from New Zealand waters between 1998 and 2008

Pacific Conservation Biology ◽

10.1071/pc090217 ◽

2009 ◽

Vol 15 (3) ◽

pp. 217 ◽

Cited By ~ 11

Author(s):

Karen A Stockin ◽

Padraig J Duignan ◽

Wendi D Roe ◽

Laureline Meynier ◽

Maurice Alley ◽

...

Keyword(s):

New Zealand ◽

Causes Of Death ◽

Published Data ◽

Common Dolphin ◽

Post Mortem ◽

Age Classes ◽

Dolphin Population ◽

Causes Of Mortality ◽

Related Mortality ◽

Beach Cast

Post-mortem examinations provide valuable information on sources of mortality for marine mammal populations. However, no published data exist to describe causes of death in the New Zealand population of Common Dolphin (Delphinus sp.). In order to examine the proportion of human and non-human induced mortality affecting this population, necropsies were conducted on 133 individuals that stranded around the New Zealand coastline between 1998 and 2008. Of these, 92.5% (n=123) were found as beach cast carcasses, with just 7.5% (n=10) as live strandings that subsequently died or that were euthanized on humane grounds. The sample included 54 males, 67 females and 12 animals of unknown sex from a range of age classes. Of the individuals for which cause of mortality could be established, 41.2% (n=35) were classified as human induced, with 28.2% (n=24) of carcasses exhibiting evidence of net entanglement. A further 10.6% and 32.9% of mortality was attributable to disease and natural (non-human related) causes, respectively. Few examples of disease were detected, but this may be at least partly a consequence of sampling constraints. Of the carcasses assessed, 68.6% of individuals exhibited some form of parasitism. Parasites identified were typical of the genus and considered to be present in low to moderate burdens. The proportion of beach cast carcasses exhibiting evidence of net entanglement suggests that fisheries-related mortality maybe higher than that previously considered for the New Zealand Common Dolphin population.

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Genetic analysis of production traits in italian new zealand white and california pure-bred populations

Genetics Selection Evolution ◽

10.1186/1297-9686-12-3-296 ◽

1980 ◽

Vol 12 (3) ◽

pp. 296 ◽

Cited By ~ 5

Author(s):

E Randi ◽

RE Scossiroli

Keyword(s):

New Zealand ◽

Genetic Analysis ◽

Production Traits

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A genetic analysis of the pea crabs (Decapoda: Pinnotheridae) of New Zealand

Marine Biology ◽

10.1007/bf01313649 ◽

1991 ◽

Vol 108 (3) ◽

pp. 403-410 ◽

Cited By ~ 13

Author(s):

P. M. Stevens

Keyword(s):

New Zealand ◽

Genetic Analysis

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Quantifying the effects of the M7.8 November 14, 2016 earthquake on rainfall-induced landslide triggering and reactivation, Kaikoura, New Zealand

10.5194/egusphere-egu2020-12409 ◽

2020 ◽

Author(s):

Brenda Rosser ◽

Katie Jones ◽

Chris Massey ◽

Salman Ashraf ◽

Georgia Strawbridge ◽

...

Keyword(s):

New Zealand ◽

Airborne Lidar ◽

Historical Period ◽

Storm Event ◽

Storm Events ◽

Channel Network ◽

Ground Shaking ◽

Strongly Coupled ◽

Change Models ◽

Landslide Debris

The 2016 Mw 7.8 Kaikoura Earthquake in Canterbury, New Zealand produced one of the most complex fault ruptures observed in the historical period and produced strong ground shaking. As a consequence, over twenty-nine thousand landslides were triggered over a total area of about 10,000 km2 with the majority concentrated in a smaller area of about 3,600 km2 (Massey et al 2018). In addition, hillslopes in the affected area were severely damaged by tension cracking and dilation. Large volumes of landslide debris generated during the earthquake remain stored in the landscape and the potential for rainfall to trigger landslides on the failed and partially failed hillslopes is anticipated to be elevated for the foreseeable future. Despite this little is known about the increase in landslide hazard and the timeframe over which this hazard will be elevated.We used airborne LiDAR captured immediately after the earthquake (November 2016), and at six consecutive dates between November 2017 and April 2019&#160; to develop high resolution surface change models to construct an inventory of rainfall-induced landslides and reactivated landslides following the earthquake. The results were compared with landslide inventories for a series of significant storm events between 1880 and 2019 which were compiled from various sources, including mapping from available aerial photography and satellite imagery collected between 1961 and 2019.Analysis of the landslide inventories indicates that rainfall triggering thresholds for landslides on these highly cracked and dilated slopes is lower than before the earthquake which has resulted in a significant increase in landslide frequency for a given rainfall amount through the initiation of new landslides on weakened slopes, reactivation of existing landslides and reworking of landslide debris stored on the landscape. Most of the landslides triggered by rainfall following the earthquake were highly mobile debris flows that were strongly coupled to the channel network. Preliminary results suggest that the highest rates of post-earthquake landslide initiation (for both new and reactivated landslides) occurred in the first major storm event following the earthquake and the rate has reduced with time since the earthquake. Maximum landslide size (area) also decreased with time following the earthquake. Quantification of rates of post-EQ rainfall-induced landsliding using LiDAR differencing and aerial photo interpretation will further our understanding of post-earthquake landscape recovery.

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