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52-528: The Kaikōura Canyon is a geologically active submarine canyon located southwest of the Kaikōura Peninsula off the northeastern coast of the South Island of New Zealand. It is 60 kilometres (37 mi) long, and is generally U-shaped. The canyon descends into deep water and merges into an ocean channel system that can be traced for hundreds of kilometres across the deep ocean floor. At the head of

104-461: A NIWA expedition found that marine life in the canyon was recovering faster than expected, and observed high densities of sea cucumbers and urchins in some areas. In 2019, results of tsunami modelling studies were reported, seeking to explain the 7-metre (23 ft) runup that was observed locally in Kaikōura following the earthquake. The modelling indicated that when combined with the direct effects of

156-581: A bipartite life cycle where larvae are pelagic before settling out of the plankton to live on a reef. While these fish travel varying distances during their life history, their larvae have the potential to move tens to hundreds of km, more than the more sedentary adults and juveniles, which have home ranges of <1 m to a few km. Adults and juveniles of some species travel tens to hundreds of kilometers as they mature to reach appropriate habitats (e.g., such as coral reef, mangrove and seagrass habitats) or to migrate to spawning areas. When adults and juveniles leave

208-497: A density of around 500 individuals per square metre on the canyon floor, ten times as many as previously found anywhere else. The biomass is estimated to be 100 times greater than reported in other deep sea locations. The abundance of fish in the canyon was estimated at around 5,000 fish per hectare, ten times as many as in the north Pacific. The Kaikōura Canyon is partly within the Hikurangi Marine Reserve that

260-458: A hillslope) observed in submarine canyons. Mass wasting is the term used for the slower and smaller action of material moving downhill. Slumping is generally used for rotational movement of masses on a hillside. Landslides, or slides, generally comprise the detachment and displacement of sediment masses. It is now understood that many mechanisms of submarine canyon creation have had effect to greater or lesser degree in different places, even within

312-515: A large submarine landslide had occurred. The abundant sealife in the canyon that had been identified in earlier studies had been severely affected by the landslide. An estimated 850 million tonnes of sediment had flowed into deeper water, and a turbidity current travelled more than 600 km (370 mi) along the Hikurangi Channel. The Kaikōura Canyon is deeply incised into the narrow, tectonically active , continental margin and

364-469: A marine reserve, they become vulnerable to fishing. However, larvae can generally leave a reserve without elevated risk because of their small size and limited fishery exposure. Effective networks account for the movement patterns of target species at each life cycle stage. Given a strong, consistent current, siting marine reserves upstream increases downstream populations. Marine reserves are distinct from marine parks , and marine sanctuaries , but there

416-1321: A network must respect larval dispersal and movement patterns of species that are targeted for protection. Existing ecological guidelines for designing networks independently focus on achieving either fisheries, biodiversity or climate change objectives or combinations of fisheries and biodiversity or biodiversity and climate change. These three goals have different implications for network design. The most important are reserve size and protection duration (permanent, long term, short term, or periodic closures). Maintaining diversity involves protecting all species. Generally this involves protecting adequate examples of each major habitat (e.g., each type of coral reef, mangrove and seagrass community). Resiliency to threats improves when multiple examples of each habitat are protected. To address biodiversity or climate change, reserves 4–20 km across are recommended, because they protect larger populations of more species. Protecting areas that have already proven resilient to ecological changes and/or are relatively well-protected by other protocols are likely to better survive climate change as well. Reserves 0.5–1 km across export more adults and larvae to fished areas, potentially increasing recruitment and stock replenishment there. Such small reserves are common in

468-414: A return period of 150 years. Prior to 2016, there had been no large seismic events centred close to Kaikōura since written records of the area began in about 1840 AD, but lichen-dating of rock-falls suggests that there may have been a major earthquake in the vicinity 175 years ago. This correlates with the estimated amount of time it would have taken to accumulate the sediment deposits seen at

520-426: A sea with a bed significantly below sea level is cut off from the larger ocean to which it is usually connected. The sea which is normally repleted by contact and inflow from the ocean is now no longer replenished and hence dries up over a period of time, which can be very short if the local climate is arid. In this scenario, rivers that previously flowed into the sea at a sea level elevation now can cut far deeper into

572-527: A significant threat to the surrounding area, especially coastal infrastructure such as roads and houses. Historical accounts of canyon-related tsunami in this region are uncertain. Geological evidence is also limited, and no palaeotsunami specific studies have been carried out to date. However, in archaeological literature, there are some possible indications of past marine inundation events. Marine sediments can be seen to overlie an historical Māori occupation site on Seddon's Ridge, near South Bay, adjacent to

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624-750: Is a major fishery threat. Local practices such as overfishing, blast fishing, trawling, coastal development and pollution threaten many marine habitats. These threats decrease ecosystem health and productivity and adversely affect focal and other species. Such practices can also decrease resilience. Some practices that originate beyond reserve boundaries (e.g., runoff ) can be mitigated by considering their impacts within broader management frameworks. Areas that are not threatened by such practices and that are adjacent to other unthreatening areas may be better choices for reserves. Networks of marine reserves can support both fisheries management and biodiversity conservation . The size, spacing and location of reserves within

676-569: Is believed to occur as the result of at least two main process: 1) erosion by turbidity current erosion; and 2) slumping and mass wasting of the continental slope. While at first glance the erosion patterns of submarine canyons may appear to mimic those of river-canyons on land, several markedly different processes have been found to take place at the soil/water interface. Many canyons have been found at depths greater than 2 km (1 mi) below sea level . Some may extend seawards across continental shelves for hundreds of kilometres before reaching

728-686: Is common. The review indicated that effective marine reserves are more than twice the size of the home range of focal/target species (in all directions). The presence of effective marine management outside the reserve may allow smaller reserves. Reserve size recommendations apply to the specific habitats of focal species, not the overall size. For example, coral reef species require coral reef habitats rather than open ocean or seagrass beds. Marine reserve whose boundaries are extensively fished benefit from compact shapes (e.g., squares or circles rather than elongated rectangles). Including whole ecological units (e.g., an offshore reef) can reduce exports where that

780-724: Is desired. Minimum sustainable population sizes have not been determined for most marine populations. Instead, fisheries ecologists use the fraction of unfished stock levels as a proxy. Meta-analyses suggest that maintaining populations above ~37% of those levels generally ensures stable populations, although variations in fishing pressure allow fractions as small as 10% or as large as 40% (to protect species such as sharks and some grouper that have lower reproductive output or slower maturation). Higher fractions of habitat protection may protect areas vulnerable to disturbances such as typhoons or climate change. 20–30% protection can achieve fisheries objectives in areas with controlled fishing pressure and

832-421: Is only circumstantial. However, it does indicate that the ocean has inundated past coastal settlements in the region, as a result of a severe storm surge or tsunami. Rapidly accumulating sandy sediment on a steep slope in an active tectonic region is likely to be susceptible to failure during moderately large earthquakes . Strong ground shaking associated with rupture on nearby faults can be expected to reduce

884-517: Is prohibited, marine reserves may also be "no-take MPAs,” which strictly forbid all extractive activities, such as fishing and kelp harvesting. As of 2007 less than 1% of the world's oceans had been set aside in marine reserves. Benefits include increases in the diversity, density, biomass, body size and reproductive potential of fishery and other species within their boundaries. As of 2010, scientists had studied more than 150 marine reserves in at least 61 countries and monitored biological changes inside

936-466: Is the main sediment source of the 1,500 km (930 mi) long Hikurangi Channel , which supplies turbidites to the Hikurangi Trough , as well as to low parts of the oceanic Hikurangi Plateau , and to the edge of the southwest Pacific Basin . It is thought to be the sink for the coastal sediment transport system that carries large amounts of erosional debris northwards up the coast from

988-772: Is the minimum level of habitat protection recommended by IUCN - WCPA . Many fish species congregate to facilitate spawning. Such congregations are spatially and temporally predictable and increase the species' vulnerability to overfishing. Species such as groupers and rabbitfishes travel long distances to congregate for days or weeks. Such gatherings are their only opportunities to reproduce and are crucial to population maintenance. Species such as snappers and parrotfishes congregate in feeding or resting areas. Juveniles may congregate in nursery areas without adults. Such special areas may require only seasonal protections if at other times no vital activities are taking place. Such reserves must be spaced to allow focal species to journey among them. If

1040-868: The Coral Triangle , species at lower trophic levels that have smaller maximum sizes, faster growth and maturation rates and shorter life spans tend to recover more quickly than species having the opposite characteristics. For example, in the Philippines, populations of planktivores (e.g., fusiliers) and some herbivores (e.g., parrotfishes) recovered in < 5–10 years in marine reserves, while predators (e.g., groupers) took 20–40 years. Increased fishing pressure adversely affects recovery rates (e.g., Great Barrier Reef and Papua New Guinea). Long-term protection allows species with slower recovery rates to achieve and maintain ecosystem health and associated fishery benefits. Permanent protection protects these species over

1092-639: The Coral Triangle , where they benefited some fisheries. Connectivity is the linking of local populations through the (voluntary) dispersal of individuals. Connected reserves are close enough to each other that larvae, juveniles or adults can cross from one to another as their behavior patterns dictate. Connectivity is a key factor in network design, since it allows a disturbed reserve to recover by recruiting individuals from other, potentially overpopulated, reserves. Effective networks spaced reserves at distances of <15 km from each other, with smaller reserves spaced more closely. Most coastal fish species have

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1144-587: The shear strength of the sandy sediment deposit at the canyon head and may trigger mass failures . It was estimated that an earthquake magnitude 8 on the Richter magnitude scale or shaking equivalent to V ( Moderate ) on the Mercalli intensity scale would be enough to trigger such an event. The ō region is adjacent to the Marlborough fault zone . There are a number of faults in this area predicted to have

1196-444: The water depths as great as 3,000 meters (9,800 ft) where canyons have been mapped, as it is well established (by many lines of evidence) that sea levels did not fall to those depths. The major mechanism of canyon erosion is thought to be turbidity currents and underwater landslides . Turbidity currents are dense , sediment-laden currents which flow downslope when an unstable mass of sediment that has been rapidly deposited on

1248-457: The Kaikōura Canyon have found that it is a highly productive ecosystem with 10 to 100 times the density of marine life found in other deep sea habitats. Prior to the 2016 Kaikōura earthquake , studies had indicated the likelihood of a submarine landslide in the canyon, potentially producing a hazardous tsunami for the nearby Kaikōura coastline. Following the earthquake, it was found that

1300-547: The Kaikōura Canyon, the depth of water is around 30 metres (98 ft), but it drops rapidly to 600 metres (2,000 ft) and continues down to around 2,000 metres (6,600 ft) deep where it meets the Hikurangi Channel . Sperm whales can be seen close to the coast south of Goose Bay, because the deep water of the Kaikōura Canyon is only one kilometre (0.62 mi) off the shoreline in this area. Studies of

1352-510: The Kaikōura peninsula. These deposits indicate that marine inundation occurred sometime within the last 150–200 years. Seddon's Ridge is an uplifted beach ridge, and has a long history of Māori settlement. An older village site dating from approximately 650 years before present, situated approximately 350 metres from the shoreline, contains reworked oven stones which are overlain by marine overwash deposits. Without accompanying reliable geological data, this kind of archaeological evidence

1404-487: The Mediterranean sea basin was flooded. One relevant consequence is that the submarine canyons eroded are now far below the present sea level. Marine reserve A marine reserve is a type of marine protected area (MPA). An MPA is a section of the ocean where a government has placed limits on human activity. A marine reserve is a marine protected area in which removing or destroying natural or cultural resources

1456-625: The South Island of New Zealand and moves northward to the east of the South Island to turn east into the open Pacific Ocean above the depths of the Hikurangi Trough . This ocean current, which is called the Southland Current in New Zealand, meets the subtropical East Cape Current, coming from the north, off Kaikōura. The boundary between these two ocean currents is known as a subtropical front . Mixing of these currents leads to

1508-458: The absence of a persistent linking current. Their isolation (low connectivity) requires such areas to be largely self-replenishing. This leaves them less resilient to disturbance. Sustaining their marine species requires a higher fraction of living areas to be protected. Coral reef fish species recovery rates (from e.g., overfishing) depend on their life history and factors such as ecological characteristics, fishing intensity and population size. In

1560-837: The abyssal plain. Ancient examples have been found in rocks dating back to the Neoproterozoic . Turbidites are deposited at the downstream mouths or ends of canyons, building an abyssal fan . Submarine canyons are more common on the steep slopes found on active margins compared to those on the gentler slopes found on passive margins . They show erosion through all substrates, from unlithified sediment to crystalline rock . Canyons are steeper, shorter, more dendritic and more closely spaced on active than on passive continental margins. The walls are generally very steep and can be near vertical. The walls are subject to erosion by bioerosion , or slumping . There are an estimated 9,477 submarine canyons on Earth, covering about 11% of

1612-597: The bottom of the bed now exposed. The Messinian salinity crisis is an example of this phenomenon; between five and six million years ago, the Mediterranean Sea became isolated from the Atlantic Ocean and evaporated away in roughly a thousand years. During this time, the Nile River delta, among other rivers, extended far beyond its present location, both in depth and length. In a cataclysmic event,

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1664-478: The canyon head in the 2006 studies. Therefore, the conclusion can be drawn that sediment in the canyon head gully had failed previously, and flowed down the canyon as a major turbidity current released by this earthquake. A landslide-generated tsunami represents a large potential hazard to the area from South Bay to Oaro . An extreme event has been modelled, incorporating failure of the entire landslide mass identified by Lewis & Barnes. These simulations indicate

1716-521: The capacity to produce such an event. The most likely are the Hope Fault , previously New Zealand's most active fault , and the larger Alpine Fault . The lesser-known Hundalee Fault also terminates near the Kaikōura coast, and although it is not as large as other faults in the area, it still has the potential to trigger a submarine landslide event. The return period for major magnitude 8 or intensity V earthquakes at Kaikōura has been estimated to be in

1768-541: The continental slope. Different mechanisms have been proposed for the formation of submarine canyons. Their primary causes have been subject to debate since the early 1930s. An early and obvious theory was that the canyons present today were carved during glacial times, when sea level was about 125 meters (410 ft) below present sea level, and rivers flowed to the edge of the continental shelf. However, while many (but not all) canyons are found offshore from major rivers, subaerial river erosion cannot have been active to

1820-412: The displacement of sediment accumulating at the mouth of the canyon. Sediment consisting of fine sand and silt is continually deposited at the head of the Kaikōura Canyon, and by 2006 it was estimated that a total volume of 0.24 cubic kilometres (0.058 cu mi) had accumulated. Studies identified that a near-field tsunami caused by the displacement of this sediment in a submarine landslide could pose

1872-531: The formation of offshore eddies , and some turbulence reaching to the depths of the Hikurangi Trough and Kaikōura Canyon. The currents south of the Kaikōura Peninsula in particular form a complex flow structure, as warm water and cold water mix with the addition of inland water from the rivers. These currents, eddies and upwellings change seasonally between summer and winter and also in response to

1924-637: The harvest to less than the increase achieved during closure, although at greatly reduced recovery rates. Some habitats and species are better prepared environmental changes or extremes. These include coral communities that handle high sea surface temperature (SST); areas with variable SSTs and carbonate chemistry and areas adjacent to undeveloped low-lying inland areas that coastal habitats can expand into as sea levels rise. Such areas constitute climate change refugia and can potentially better protect biodiversity than more fragile areas. They may also provide fishery benefits, since habitat loss from climate change

1976-403: The head of the modern deposit indicate that it was likely to fail as a result of shaking associated with a major earthquake. Failure would result in the collapse of an estimated quarter of a cubic kilometre of unconsolidated sediment. The canyon-head gully of the Kaikōura Canyon faces northwards, obliquely towards the shore. Consequently, the initial motion of a debris avalanche in the gully, and

2028-544: The large earthquake, a submarine landslide with a volume of 4.5–5.2 km (1.1–1.2 cu mi), occurring 10 to 20 minutes after the main earthquake rupture would be consistent with the observed 7-metre runup. 42°33′00″S 173°43′01″E  /  42.550°S 173.717°E  / -42.550; 173.717 Submarine canyon About 3% of submarine canyons include shelf valleys that have cut transversely across continental shelves, and which begin with their upstream ends in alignment with and sometimes within

2080-659: The life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and were located to accommodate movement patterns among them. Movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by factors such as size, sex, behaviour, density, habitat characteristics, season, tide and time of day. For example, damselfishes, butterflyfishes and angelfishes travel <0.1–0.5 km, while some sharks and tuna migrate over thousands of kilometres. Larval dispersal distances tend to be <5–15 km, and self-recruitment to new habitat

2132-782: The location of such special areas is unknown, or is too large to include in a reserve, management approaches such as seasonal capture and sales restrictions may provide some protection. Sea turtle nesting areas, dugong feeding areas, cetacean migratory corridors and calving grounds are examples of other special areas that can be protected seasonally. Other types of special areas include isolated habitats that have unique assemblages and populations, habitats that are important for endemic species and highly diverse areas. Isolated populations (e.g. those on remote atolls ) have high conservation value where they harbor endemic species and/or unique assemblages. A location or population 20–30 km from its nearest neighbor generally qualifies as isolated in

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2184-756: The long-term. Short-term protections do not allow slow-recovering species to reach or maintain stable populations. In some Coral Triangle countries (e.g., Papua New Guinea and Solomon Islands), short term protections are the most common form of traditional marine resource management. These protections can help address problems at lower trophic levels (e.g., herbivores) or allow spawning to succeed. Other reasons for adopting short-term protections include allowing communities to stockpile resources for feasts or close areas for cultural reasons. Short-term/periodic reserves also may function as partial insurance by enhancing overall ecosystem resilience against catastrophes. Reopened reserves can be protected by management controls that limit

2236-566: The mouths of large rivers , such as the Congo River and the Hudson Canyon . About 28.5% of submarine canyons cut back into the edge of the continental shelf, whereas the majority (about 68.5%) of submarine canyons have not managed at all to cut significantly across their continental shelves, having their upstream beginnings or "heads" on the continental slope, below the edge of continental shelves. The formation of submarine canyons

2288-402: The order of 150 years based on what is known about the return time of earthquake events for regional faults in the Kaikōura area. There is evidence of past failures in similar deposits in the Kaikōura Canyon, in the presence of numerous sand and gravel turbidite deposits in cores taken from the canyon axis. Ground acceleration with a peak of 0.44 g is estimated at the Kaikōura township for

2340-428: The potential for large tsunami runup heights along this section of coast. The effects could be more severe here if such an event coincided with storm activity or high tides . It is estimated to take approximately a century to accumulate enough sediment in the canyon head to generate a major mass failure. Therefore, as at 2006, there was already enough sediment to pose a significant hazard. Evidence of tensional cracks at

2392-620: The reserves. The number of species in each study ranged from 1 to 250 and the reserves ranged in size from 0.006 to 800 square kilometers (0.002 to 310 square miles). In 2014, the World Parks Association adopted a target of establishing no-take zones for 30% of each habitat globally. A review of studies of 34 families (210 species) of coral reef fishes demonstrates that the design of a marine reserve has important implications for its ability to protect habitat and focal species. Effective reserves included habitats that support

2444-420: The resulting tsunami, is towards the shore of South Bay and the southern side of the Kaikōura Peninsula. In November 2016, the Kaikōura earthquake caused submarine mudslides and sediment flows that devastated the deep-sea life in the canyon. An estimated 850 million tonnes of sediment was displaced into deep ocean, and a turbidity current travelled more than 600 km along the Hikurangi Channel. In September 2017,

2496-413: The rivers draining the tectonically active mountains of the South Island . The upper 200 m (660 ft) of the ocean off the New Zealand coast typically consists of warm, saline and nutrient-poor subtropical surface water in the north, and cold, less saline but more nutrient-rich subantarctic surface water in the south. A subantarctic ocean current of surface water flows around the southern part of

2548-507: The same canyon, or at different times during a canyon's development. However, if a primary mechanism must be selected, the downslope lineal morphology of canyons and channels and the transportation of excavated or loose materials of the continental slope over extensive distances require that various kinds of turbidity or density currents act as major participants. In addition to the processes described above, submarine canyons that are especially deep may form by another method. In certain cases,

2600-551: The topography of the seafloor and surface winds. In 2006, scientists from the National Institute of Water and Atmospheric Research (NIWA) used the research vessel RV  Tangaroa to explore the canyon over a period of three days. They found that the Kaikōura Canyon has an ecosystem that is 10 to 100 times more abundant than other comparable deep sea habitats. They found marine organisms such as sea cucumbers , heart urchins , bristle worms and spoon worms with

2652-471: The upper slope fails, perhaps triggered by earthquakes. There is a spectrum of turbidity- or density-current types ranging from " muddy water" to massive mudflow, and evidence of both these end members can be observed in deposits associated with the deeper parts of submarine canyons and channels, such as lobate deposits (mudflow) and levees along channels. Mass wasting , slumping, and submarine landslides are forms of slope failures (the effect of gravity on

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2704-402: Was established off the Kaikōura coast in 2014. This marine reserve covers an area of 10,416 hectares (25,740 acres) south of the township. The reserve is the largest and deepest marine reserve adjacent to any of New Zealand's three main islands. No fishing, harvesting or mining is allowed in the reserve. Prior to 2016, there was a known risk of an earthquake-triggered tsunami resulting from

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