Hotspot Watch 22 January 2021

Hotspot Watch 22 January 2021

Source: NIWA – National Institute of Water and Atmospheric Research

A weekly update describing soil moisture patterns across the country to show where dry to extremely dry conditions are occurring or imminent. Regions experiencing significant soil moisture deficits are deemed “hotspots”. Persistent hotspot regions have the potential to develop into drought.

Facts: Soil Moisture

Moderate-to-heavy rainfall was observed across the western North Island during the past week, with areas in southern Auckland, Waikato, Taranaki and northern Manawatu-Whanganui receiving about 30-60mm. Light rainfall was observed in the upper North Island, generally less than 25mm. However, eastern parts of the North Island received meagre rainfall, with most locations receiving 10mm or less. This resulted in minor-to-moderate soil moisture increases in the western North Island and minor-to-moderate soil moisture decreases in eastern parts of the North Island. Little change was observed elsewhere. The driest soils across the North Island, when compared to normal for this time of the year, are found in the Far North, Coromandel and small parts of the east coast. Meanwhile, the wettest soils for this time of year for the North Island are in New Plymouth District and southern Manawatu-Whanganui.

Hotspots are currently in place in much of Northland, parts of Auckland, northern Waikato and a small portion of East Cape, while hotspots have strengthened in eastern Wairarapa and expanded to include the eastern Tararua District and coastal Hawke’s Bay. The New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District. Widespread dry-to-extremely dry soils are in place in the remainder of Northland, Auckland and northern Waikato.

Widespread heavy rain fell across the west and south of the South Island during the past week, with parts of the West Coast and western Southland receiving over 150mm, and parts of Otago and eastern Southland receiving over 50mm. However, rainfall was generally below 20mm across the Canterbury and Marlborough regions. This resulted in large soil moisture increases in the west and south of the South Island, with small soil moisture increases in parts of the Canterbury and Marlborough regions. The driest soils in the South Island compared to normal for this time of year are located in coastal Hurunui District, while the wettest soils for this time of the year for the South Island are found in southern Canterbury and interior Otago.

A small hotspot remains in place in coastal Hurunui District.

Outlook and Soil Moisture

Saturday will be a mostly dry day across the North Island before a band of showers brings 5mm or less to western areas on Sunday. Dry weather is expected nearly everywhere from Monday to Wednesday (25-27 January), while hot temperatures will contribute to increased evapotranspiration. Rain and showers then look to arrive on Thursday as a front moves across the North Island. Weekly rainfall totals look to generally below 20mm for most of the North Island, with some areas of the north and east receiving 10mm or less.

Due to the light rain in the next week and the hot temperatures expected on Tuesday and Wednesday, most of the North Island will see small-to-moderate soil moisture decreases. However, moderate-to-large soil moisture decreases will be possible along the east coast. This will likely result in all current North Island hotspots strengthening, particularly those in the east.

A band of rain will bring 20-50mm to the West Coast and western Southland on Saturday. The west of the South Island will remain at least showery from Sunday to Tuesday (24 – 26 January), while the eastern South Island remains dry. On Tuesday, eastern areas of the South Island will become very hot, which will contribute to increased evapotranspiration. A front will bring a band of rain and relief from hot temperatures on Wednesday and early Thursday, with the heaviest rain expected across the west of the South Island. Weekly rain totals may exceed 75-100mm for parts of the West Coast and western Southland, with 20-30mm in parts of eastern Southland and Otago. The remainder of the South Island looks to see less than 20mm of rain.

Due to the expected rainfall in the next week, small-to-moderate soil moisture increases are likely in the west and south of the South Island. However, additional soil moisture decreases are likely in Canterbury and Marlborough. This will at least slightly strengthen the current hotspot in the Hurunui District, while new hotspots may emerge in Marlborough and central Canterbury.

Background:

Hotspot Watch: a weekly advisory service for New Zealand media. It provides soil moisture and precipitation measurements around the country to help assess whether extremely dry conditions are imminent. 

Soil moisture deficit:  the amount of water needed to bring the soil moisture content back to field capacity, which is the maximum amount of water the soil can hold.

Soil moisture anomaly:  the difference between the historical normal soil moisture deficit (or surplus) for a given time of year and actual soil moisture deficits.

Definitions: “Extremely” and “severely” dry soils are based on a combination of the current soil moisture status and the difference from normal soil moisture (see soil moisture maps)

Hotspot: A hotspot is declared if soils are “severely drier than normal” which occurs when Soil Moisture Deficit (SMD) is less than -110 mm AND the Soil Moisture Anomaly is less than -20 mm.

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Pictured above: Soil Moisture Anomaly Maps, relative to this time of year. The maps show soil moisture anomaly for the past two weeks.

New Zealand Drought Index (NZDI)

As of 19 January, the New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District. Widespread dry-to-extremely dry soils are in place in the remainder of Northland, Auckland and northern Waikato. Please note: some hotspots in the text above may not correspond with the NZDI map. This difference exists because the NZDI uses additional dryness indices, including one which integrates the rainfall deficit over the past 60 days. Changes are therefore slower to appear in the NZDI compared to soil moisture anomaly maps that are instantaneously updated.

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There’s snow business in the mountains

There’s snow business in the mountains

Source: NIWA – National Institute of Water and Atmospheric Research

On a still and sunny December day when most Kiwis were looking longingly towards the beach, two NIWA researchers staff had their eyes firmly on the Southern Alps.

Adrian Aarsen and James Townshend jumped on board a helicopter from Queenstown to complete a last-minute piece of work before the Christmas break – servicing NIWA’s Mt. Larkins snow and ice monitoring station.

As far as an end-of-year job goes – working at 1915m altitude on a bluebird day – the Mt. Larkins work is pretty good.

The snow and ice network

The Mt. Larkins station is part of a network of 11 NIWA snow and ice stations in New Zealand.  Together, the network is creating a valuable long-term record of alpine weather and snow measurements, like depth and density.

NIWA hydrologist Dr Christian Zammit who manages the research programme, says the network was set up for two main reasons: to measure how much water was being stored as snow and to detect climate change impacts.

Work on the network began in 2008. By 2013, 11 snow and ice monitoring stations had been set up, representing a range of distinct high-altitude areas of the country between 800 and 2200 metres above sea-level including Aoraki-Mt. Cook, Mt. Aspiring, Arthur’s Pass, Tongariro and Fiordland.  

The stations measure the depth, density and temperature of snow, as well as a range of other climate measurements such as precipitation, wind speed, temperature and humidity.

Dr Zammit says snow is a valuable economic resource for New Zealand, so understanding the amount, seasonal nature and long-term changes to snow and ice is hugely important – especially with a warming climate.

Snow melt contributes to as much as 30% of water that flows into major South Island hydro-electricity lakes. Large areas of the South Island rely directly on water from snow melt for irrigation and the ski industry cannot exist without snow. In 2019 alone, there were 1.7 million visits to ski fields in New Zealand.

Dr Zammit says climate change will impact both the amount and seasonality of snowfall in New Zealand.

“We expect the snowline to increase in altitude with time and there is an expectation that there will be less snow. However, with climate change, extremes get more extreme. So, you could have less snow days, but you could have a larger amount of snow falling during storm events.”

Dr Zammit says that because the network has only been operating for seven years, more years of data will need to be collected to before researchers can confidently say how climate change is impacting our snow season, though NIWA’s end of summer snowline survey has documented a long-term decrease in glacier coverage on the Southern Alps over the last 43 years.

As well as a need for long-term information, Dr Zammit says several organisations use real-time data from the network. The Avalanche forecasting service generated by Mountain Safety Council is one of them.

“Data from the network is the only information they use to predict the state of the snowpack, both in and outside of the ski domain. Their daily avalanche risk forecasts are based on this information, their knowledge of the domain and access to weather forecast information.”

Other main users of the network are hydro-electricity generators who use the data to estimate the volume and seasonality of snow and ice melt flowing down rivers. The information informs decision-making about when dams should be opened to generate electricity, as well as how electricity is stored and transported.

A “10 out of 10” view

NIWA field researchers visit each snow and ice station twice a year.

At the Mt. Larkins station in December, there is some snow high on the alps.

Dr Zammit describes 2020’s snow season as being “on the lower side” – winter was warm with little snowfall until a few big dumps late in the snow season.

For safety reasons, the stations are only visited on calm, sunny days. Mr. Aarsen says they waited a month for good weather to visit the Mt. Larkins site in December.

After a 15-minute flight, the researchers have three hours to complete the work needed before the helicopter returns to collect them.

The purpose of the visit is to replace fuel and antifreeze, collect snow samples, empty the snow collector measuring snow fall and make sure the equipment is recording accurate data.  

Mr Aarsen says despite the sturdy design and build of the stations, lightning, extreme weather and the pesky destructive kea means the technicians also have to fix any issues that might have sprung up since the last visit – in this case some damage caused by a snow storm.

“You’re putting in these instruments and you’re thinking ‘man, I hope this equipment will survive the elements’. The intensity of what the stations withstand is amazing.

“Kea will come and pick at anything they can. Especially the wind sensors, they love picking them apart. We’ve had a lot of equipment ruined by kea-. Once they get into something, they get into it pretty hard.”

While the researchers work in t-shirts in December, Mr Aarsen says working in minus zero conditions during winter is a different story.

“The cold and snow make everything harder. It makes moving around or trying to undo screws really tricky when it’s freezing and you’re wearing a lot of layers. There can be up to a metre and a half of snow at Larkins.”

As a safety precaution, the researchers bring up a survival bag that contains a tent, gas-cooker, food, sleeping bags and extra layers if a freak shift in the weather meant a helicopter couldn’t safely collect the workers.

Despite the “10-out-of-10 view” from the top of the monitoring station, Mr Aarsen says looking out across the Main Divide isn’t the highlight of the trip.

“The chopper ride is definitely the highlight… it’s got to be, doesn’t it?”

Further information:

Dr Christian Zammit
Hydrologist
Contact Christian

This story forms part of our 2020 Summer Series. Check out more stories from the series.

NZIER’s QSBO shows increased construction demand driving improved sentiment – Quarterly Survey of Business Opinion, January 2021

Source: New Zealand Institute of Economic Research

19 January 2021

This NZIER Quarterly Survey of Business Opinion (QSBO) showed a further improvement in business confidence in the final quarter of 2020. A smaller proportion of businesses expect a deterioration in general economic conditions, and firms also reported trading in their own business held up in the December 2020 quarter. On a seasonally adjusted basis, a net 16 percent of firms expect a worsening in general economic conditions, while only a net 1 percent reported reduced demand.

The media release is avilable here.

QSBO is only available to NZIER members.

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ESR and Air New Zealand partner on COVID-19 saliva testing study

Source: ESR

An ESR study investigating testing for COVID-19 in saliva has been given the green-light to commence in January.

Funded by ESR, the study will run over 2-3 months, commencing on the week of 25 January. It will involve Air New Zealand staff providing a saliva sample alongside their regular nasopharyngeal sample, known as paired sampling, so the two can be compared.

ESR Chief Scientist Dr Brett Cowan says there is a hope for saliva to be more comfortable than current methods.

“This study will go a long way to determine how saliva testing might fit, or not fit alongside nasal swab testing, within New Zealand’s unique context where we must detect and track every case. Every time our testing regime is adjusted, it needs to be based on rigorous, evidence-based science to ensure our communities have the best protection. If saliva testing is to be incorporated into our testing regime, it needs to undergo that same scrutiny for us to have confidence in its ability to detect COVID-19.”

The study will include the SalivaDirect COVID-19 testing technology developed at the Yale School of Public Health.

“Yale’s protocol needs to be adapted for the New Zealand context and we have been creating an evidence base for it along with the other options out there. Just like our gold-standard test, the nasopharyngeal sample by PCR, we need to validate results and protocols in New Zealand laboratories,” Dr Cowan says.

As the national reference laboratory, ESR is best placed to do this work and the study will involve several experiments, such as the trialling of three methods for the saliva collection.

It will also further develop laboratory procedures to best work with saliva, as it can be difficult to work with in the laboratory. “It’s sticky and bubbly,” Dr Cowan says. “This makes it much more labour intensive and difficult for laboratory staff, but we have had some clever scientists working on those issues and the study will help them along.”

Air New Zealand Chief Medical Officer Dr Ben Johnston says, for the airline’s crew, pilots and airport staff, surveillance testing for COVID-19 will be required for some time into the future.

“It’s great to be teaming up with ESR on this study to see if there is a more non-invasive and comfortable testing option which would greatly improve the experience for our people and New Zealanders.”
  
ESR are undertaking several other bodies of work alongside the study to support the evidence base, including the collection of paired samples from positive cases in managed isolation and quarantine facilities.

The results will be provided to the Ministry of Health. Dr Cowan says if the results are promising, then New Zealand may have another instrument to add alongside the nasal swab in the country’s toolbox in the fight against COVID-19.

How does a fish climb a ramp? Very, very cleverly…

How does a fish climb a ramp? Very, very cleverly…

Source: NIWA – National Institute of Water and Atmospheric Research

New Zealand’s native fish are doing their best to climb up ramps in a NIWA laboratory so scientists can learn how to better help them navigate our tricky waterways.

Hamilton-based hydroecologist Dr Eleanor Gee and her team have rigged up six ramps – each at different angles and sporting two different surface types – one smooth, the other textured ­­‑ to test how adept the fish are at making their way to the top. The idea is to simulate their upstream migration.

She’s using young fish of the whitebait species kōaro and banded kōkopu at the moment and plans to move on to redfin bullies. “These species are known to be climbers and all migrate as part of their lifecycle.”

Kōaro in particular are known to be excellent climbers and able to penetrate further inland than other whitebait species after spending their larval life in the sea.

Migrating native fish face a range of issues in our waterways, including manmade barriers such as dams, weirs and culverts that prevent them reaching their preferred freshwater habitats.

“What we’re trying to do is find out the limits of the known climbing fish by testing them on ramps of varying steepness. Ultimately, we’d like to look at whether larger or older fish find it more difficult. We know some small fish can climb near vertical slopes, but they probably can’t do that their entire lives so we want to find out at what stage they stop.”

Dr Gee says the ability to climb is not a particularly common strategy for fish but it allows the fish to migrate further upstream than other species they may compete with. However, more than one-third of New Zealand’s native freshwater fish migrate from the sea upstream, and that includes a number of species in decline.

“The shortjaw kōkopu is a nationally threatened species and is also a climber, so it’s important to find as much as possible about climbing so we can manage them in the best possible way.”

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Interestingly, not all climbing fish climb in the same way. Kōaro and banded kōkopu use an alternating limb movement, like swimming freestyle, while bullies go for a bilateral movement which is more like breast-stroke, moving both limbs in the same direction at the same time. “It’s pretty impressive watching them shuffle their way up these structures.”

They can also climb a long way with some known to surmount significant waterfalls depending on the steepness and the type of substrate available.

The insight Dr Gee gains from the experiments will be used to update the New Zealand Fish Passage Guidelines first introduced in 2018. The guidelines set out the recommended practice for designing infrastructure in streams that enable fish to pass through and were developed to help waterway managers, engineers, environmental officers, iwi and communities understand and implement better management of fish passage in New Zealand.

New freshwater management rules require all regional councils to identify barriers to fish passage and come up with a plan for mitigating them.

So far the experiment is providing plenty of challenges for the 100 or so fish roped in to help. “I’ve seen a kōaro get up reasonably quickly and then experience a slippery ride to the bottom, and I’ve had a few naughty children who have decided to climb off the ramp, but it is a really fun experiment to do.”

“For me personally a lot of what drives me professionally is the contribution I can make to the public knowledge and understanding of these species. People care a lot about these treasured animals.”

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Further information:

Dr Eleanor Gee
Freshwater Hydro-Ecologist
Contact Eleanor

This story forms part of our 2020 Summer Series. Check out more stories from the series.

Hotspot Watch 15 January 2021

Hotspot Watch 15 January 2021

Source: NIWA – National Institute of Water and Atmospheric Research

A weekly update describing soil moisture patterns across the country to show where dry to extremely dry conditions are occurring or imminent. Regions experiencing significant soil moisture deficits are deemed “hotspots”. Persistent hotspot regions have the potential to develop into drought.

Facts: Soil Moisture

Meagre rainfall was observed across much of the northern, western and lower North Island during the past week, with most locations receiving 10 mm or less. However, eastern Bay of Plenty and a couple of localised areas in Hawke’s Bay received 30 mm or more. This resulted in minor to moderate soil moisture decreases across nearly all of the North Island, although slight increases were observed in northern Waikato. The driest soils across the North Island, when compared to normal for this time of the year, are found in the Far North and Aupouri Peninsula. Meanwhile, the wettest soils for this time of the year for the North Island are located in coastal Bay of Plenty and Horowhenua.

Hotspots are currently in place in much of Northland, northern Auckland, the northern Coromandel Peninsula, a small portion of East Cape, and coastal Wairarapa. The New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District, with widespread dry to extremely dry soils in the rest of Northland, Auckland, and northern Waikato.

Minimal rainfall was observed across all of the South Island during the past week, with nearly all locations receiving less than 10 mm. This resulted in moderate to large soil moisture decreases throughout the South Island. The driest soils in the South Island compared to normal for this time of the year are located in southeastern Southland, coastal Hurunui District, and Buller District, while the wettest soils for this time of the year for the South Island are found in southern Canterbury and much of eastern Otago.

During the past week a new, small hotspot has formed in coastal Hurunui District.

Outlook and Soil Moisture

Saturday will be a dry day across the North Island, before a front arrives on Sunday, bringing showers and thunderstorms, particularly to the western North Island. After a mostly dry day on Monday, another front will arrive Tuesday night and Wednesday (19-20 January) with periods of rain and isolated thunderstorms. Western portions of the North Island could receive up to 20 mm from this event, although amounts will be much lower along the east coast. Mostly dry conditions then return on Thursday and Friday. Weekly rainfall totals may reach 40-50 mm in the western North Island, with totals of 20 mm or less for much of the upper North Island. Meanwhile, the east coast is only expected to receive 10 mm or less.

Due to the expected rainfall in the next week, western portions of the North Island may see at least small soil moisture increases, while the upper North Island may observe small decreases. However, moderate to large soil moisture decreases will be possible along the east coast. This will likely result in all current North Island hotspots strengthening at least a small amount, while the hotspot in coastal Wairarapa may strengthen substantially.

After a dry Saturday, a front will bring moderate rainfall amounts to the West Coast and lower South Island on Sunday. The West Coast will remain at least showery on Monday before a strong front brings heavy rainfall to the western South Island on Tuesday (19 January). However, little of this rain is expected to reach the eastern South Island. After scattered showers on Wednesday, late next week will be mostly dry as high pressure arrives. Weekly rainfall totals may exceed 150 mm along much of the West Coast, with 40-50 mm in Southland and Otago. However, amounts will be much lower from Marlborough to Canterbury, where weekly totals may only reach 20 mm or so.

Due to expected rainfall in the next week, soil moisture increases are likely in the west and south of the South Island. However, at least small soil moisture decreases will be possible in Marlborough and Canterbury. The current hotspot in Hurunui District may strengthen at least slightly during the next week, while a new hotspot may emerge in Marlborough.

Background:

Hotspot Watch: a weekly advisory service for New Zealand media. It provides soil moisture and precipitation measurements around the country to help assess whether extremely dry conditions are imminent. 

Soil moisture deficit:  the amount of water needed to bring the soil moisture content back to field capacity, which is the maximum amount of water the soil can hold.

Soil moisture anomaly:  the difference between the historical normal soil moisture deficit (or surplus) for a given time of year and actual soil moisture deficits.

Definitions: “Extremely” and “severely” dry soils are based on a combination of the current soil moisture status and the difference from normal soil moisture (see soil moisture maps).

Hotspot: A hotspot is declared if soils are “severely drier than normal” which occurs when Soil Moisture Deficit (SMD) is less than -110 mm AND the Soil Moisture Anomaly is less than -20 mm.

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Pictured above: Soil Moisture Anomaly Maps, relative to this time of year. The maps show soil moisture anomaly for the past two weeks.

New Zealand Drought Index (NZDI)

As of 13 January, the New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District, with widespread dry to extremely dry soils in the rest of Northland, Auckland, and northern Waikato. Please note: some hotspots in the text above may not correspond with the NZDI map. This difference exists because the NZDI uses additional dryness indices, including one which integrates the rainfall deficit over the past 60 days. Changes are therefore slower to appear in the NZDI compared to soil moisture anomaly maps that are instantaneously updated.

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NIWA drones going where people can’t on the West Coast

Source: NIWA – National Institute of Water and Atmospheric Research

A team of scientists have been exploring some of New Zealand’s most remote and rugged coastal zones.

Parts of the South Island’s West Coast are so inhospitable to humans that marine biologists simply don’t know what plants and animals are there, or how they are faring.

Enter the NIWA drone team, ably assisted by the Department of Conservation and the University of Canterbury. Recently they’ve been mapping two marine reserves off the West Coast of the South Island for the Department of Conservation – Okarito and Punakaiki.

NIWA marine ecologist Dr Leigh Tait says parts of the coast are simply too dangerous to map any other way and drones have opened up a whole new method of gaining valuable insight into our marine environments.

 “One of my major concerns is that traditional monitoring methods, such as transects and quadrats (sampling at specific points) only cover small areas and are selected mainly because they’re accessible. We’ve missed a whole lot of habitats just because we can’t physically sample them.”

Of particular interest to Tait are the large kelp beds just off the coast. He describes them as sentinels of the habitats they protect.

“They’re the species that really drives productivity and offers the kind of habitat a lot of fish and animals need to survive. A lot of things hide in the kelp, a lot eat it and a lot of animals rely on it indirectly. They are the signs of a healthy ecosystem.”

Data collected by the drones, skilfully captured by NIWA’s Hamish Sutton,  will enable Tait to map those beds, discover how extensive they are and provide an estimate of the coverage of other key habitat types. Baseline maps will be produced to enable consistent long-term monitoring.

The information has been collected ahead of an expected marine heatwave this summer which will enable comparisons to be made about the effect of a warmer sea surface temperatures on the kelp beds.

“Drones or aerial imagery of some kind are really the only opportunities to really see these beds in their entirety.”

However, using drones in these remote areas requires serious planning, a lot of logistics and an intrepid spirit.

Tait says they need to be on-site the day before data collection begins to determine where to set up GPS stations and establish good lines of sight.

“We can’t fly the drones too far away from us which means getting our vehicles as close as possible.” Or, in the case of one West Coast site, lugging all the equipment 15 minutes down a track to a lookout point with the help of some DOC staff.

The team uses a high accuracy positioning system to pinpoint their sites and define just how rugged they are.

“The key thing we’ve learnt about a lot of this work is just how critical it is to have some of your specialists on the ground. My job in these scenarios is running around looking for key biological features I can identify that I can then get a high accuracy position for.”

This technique enables the team to compare the drone imagery with what’s actually on the ground. The imagery itself is captured using multi-spectral cameras – essentially six different cameras each recording a different portion of the light spectrum.

“Because we’re capturing so many different bands of light we can then put these images into machine learning algorithms that can identify each pixel or segment. We then might carry out some manipulation on some of those bands to give us vegetation layers or apply an elevation model which can tell us a lot about what species live in different shore heights.”

Tait says the amount of information gathered by the drones gives scientists a lot more context when assessing the impact of a marine heatwave for example.

“Knowing these things is pretty important and knowing it for a whole area gives us a lot more power to identify when things are going really wrong.”

NIWA’s drone team members are used to the isolated environments they work in which requires juggling weather conditions, tides and local conditions to get the job done.

“Going to hard-to-reach, rugged locations is one of my favourite pastimes. The challenge is part of the prize – they’re difficult places, hard to get to and hard to do anything about and that’s where the novelty of the work we’re doing really gets me excited.”

However, what goes on back at the office is equally as important, says Tait.

“A lot of the tools we’re using are off the back of really hard work from guys doing a lot of behind the scenes work kitting out the drones with the right attachments for all the cameras. The GPS systems don’t run by themselves and that’s been years of investment and hard grind to get those systems operating well and people trained up on them.

“When we go out to a coast and capture a beautiful rocky reef there’s been a whole team with incredible expertise that have got us there.”

For more information contact:

Dr Leigh Tait
NIWA marine ecologist

Contact Leigh

This story forms part of our 2020 Summer Series. Check out more stories from the series.

Hotspot Watch 8 January 2021

Hotspot Watch 8 January 2021

Source: NIWA – National Institute of Water and Atmospheric Research

A weekly update describing soil moisture patterns across the country to show where dry to extremely dry conditions are occurring or imminent. Regions experiencing significant soil moisture deficits are deemed “hotspots”. Persistent hotspot regions have the potential to develop into drought.

Facts: Soil Moisture

Significant rainfall was observed in much of the upper North Island during the past week, with many locations receiving 30-60 mm. Similar amounts were also observed in parts of Manawatu-Whanganui. Elsewhere, much of the east coast and lower South Island saw less than 20 mm during the past week. This resulted in moderate to large soil moisture increases in the central and upper North Island, with smaller increases in eastern areas. The driest soils across the North Island, when compared to normal for this time of the year, are now found in the Far North and Aupouri Peninsula. Meanwhile, the wettest soils for this time of the year are located in coastal Taranaki and Manawatu-Whanganui, as well as eastern Bay of Plenty.

Hotspots are currently in place in East Cape, northern Waikato (including much of the Coromandel Peninsula), southern Auckland, and much of Northland. The New Zealand Drought Index (NZDI) map below shows that meteorological drought has emerged in the Aupouri Peninsula, with widespread dry to extremely dry soils in the rest of Northland, Auckland, and northern Waikato.

Heavy rainfall was observed in much of the western and lower South Island during the past week, with many areas receiving 75 mm or more, and isolated amounts of 150 mm. However, substantially less rain fell in the upper South Island as well as northern and central Canterbury, where amounts were generally less than 20 mm. This resulted in large soil moisture increases in western and southern areas, while the upper South Island saw minor soil moisture decreases. The driest soils in the South Island compared to normal for this time of the year are located in small portions of Marlborough and Buller District, while the wettest soils for this time of the year are found in southern Canterbury and much of Otago.

No hotspots are currently found in the South Island.

Outlook and Soil Moisture

Much of the next week’s rain will fall today (8 January), with areas of heavy morning rain in the upper North Island, and widespread showers and thunderstorms in the central and eastern North Island that will produce locally heavy rainfall in excess of 40 mm. Thereafter, high pressure will be in control of the North Island’s weather through the end of next week, resulting in mostly dry weather. These days may feature isolated afternoon showers and thunderstorms, but rainfall will be very localised.   

Upper and eastern parts of the North Island may see small soil moisture decreases during the next week, with larger decreases possible in western and southern areas where rainfall totals are likely to be minimal. This could result in slight strengthening and expansion of all current hotspots in the upper North Island and East Cape.

High pressure will generally be in control of the South Island’s weather over the next week, with only a handful of weak troughs moving across southern portions of the island in coming days. This will result in weekly rainfall totals being 15 mm or less for most South Island locations.

Due to expected rainfall, at least small soil moisture decreases will be likely across most of the South Island during the next week. There is a small chance that a new hotspot will form in Marlborough during this time.

Background:

Hotspot Watch: a weekly advisory service for New Zealand media. It provides soil moisture and precipitation measurements around the country to help assess whether extremely dry conditions are imminent. 

Soil moisture deficit:  the amount of water needed to bring the soil moisture content back to field capacity, which is the maximum amount of water the soil can hold.

Soil moisture anomaly:  the difference between the historical normal soil moisture deficit (or surplus) for a given time of year and actual soil moisture deficits.

Definitions: “Extremely” and “severely” dry soils are based on a combination of the current soil moisture status and the difference from normal soil moisture (see soil moisture maps).

Hotspot: A hotspot is declared if soils are “severely drier than normal” which occurs when Soil Moisture Deficit (SMD) is less than -110 mm AND the Soil Moisture Anomaly is less than -20 mm.

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Pictured above: Soil Moisture Anomaly Maps, relative to this time of year. The maps show soil moisture anomaly for the past two weeks.

New Zealand Drought Index (NZDI)

As of 6 January, the New Zealand Drought Index (NZDI) map below shows that meteorological drought has emerged in the Aupouri Peninsula, with widespread dry to extremely dry soils in the rest of Northland, Auckland, and northern Waikato. Please note: some hotspots in the text above may not correspond with the NZDI map. This difference exists because the NZDI uses additional dryness indices, including one which integrates the rainfall deficit over the past 60 days. Changes are therefore slower to appear in the NZDI compared to soil moisture anomaly maps that are instantaneously updated.

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NIWA heads to Antarctica for critical climate, ocean research

NIWA heads to Antarctica for critical climate, ocean research

Source: NIWA – National Institute of Water and Atmospheric Research

NIWA’s flagship research vessel Tangaroa leaves soon on a six-week voyage to Antarctica, making it one of the few full scientific expeditions to the continent since the global outbreak of COVID-19.

The ship leaves Wellington and heads south with 20 science staff and 19 crew on board to learn more about key environmental and biological processes in the Ross Sea.

Voyage leader and fisheries scientist Dr Richard O’Driscoll says this is the third in a series of voyages focused on providing baseline information about the Ross Sea Marine Protected Area (MPA) established in 2017.

“This year we are focused on understanding the key processes that drive the environment and oceanography of the region and assessing the potential impacts of climate change.

“Antarctica is important because some of the processes that happen there have impacts for the whole planet.”

How effective is the Ross Sea Marine Protected Area over time?

Scientists have a range of programmes looking at everything from phytoplankton – microscopic marine algae at the base of food webs – through to water chemistry and oceanography, sampling of fish and finding out more about the distribution of whales.

“Some previous voyages had a single focus – this one is a lot more multi-disciplinary and is all tied in with the concept of long-term monitoring,” Dr O’Driscoll says.

NIWA Principal Scientist Dr Matt Pinkerton leads a five-year project called RossRAMP, funded by MBIE, which is studying the effectiveness of the Ross Sea MPA. After five years Dr Pinkerton will submit a report to the international body CCAMLR (Commission for the Conservation of Antarctic Marine Living Resources) and a formal assessment of the MPA’s effectiveness will be made after 10 years.

“We are trying to understand what is there now and looking at particular threats to the ecosystem from fishing and climate change.”

Dr Pinkerton says on this voyage scientists have nine objectives they hope to complete which includes taking bio-optical measurements to understand the colour of phytoplankton which are microscopic marine algae at the base of food webs.

“Learning more about the optical properties of phytoplankton means we can then improve satellite monitoring because that’s one of our best ways of getting a handle on what long term changes are happening in the area.”

The Antarctic Science Platform is also funding part of the voyage and will look at physical oceanography and phytoplankton, including how iron is used by plankton.

“Their growth depends a lot on the amount of iron in the water. One of the key things limiting our ability to forecast changes in plankton will be if we don’t get a handle on the mechanisms for iron,” Dr Pinkerton says.

Where are the whales?

Weather and sea ice permitting, Tangaroa will also retrieve and redeploy several moorings which have been in place for two years. Among those are three acoustic sensors which have been recording the sounds of sperm whales.

Historically common on the Ross Sea Slope, the aim is to find out where their populations are concentrated, how they interact and where they go.

“We know they eat a lot of toothfish so we want to see where they are and whether they’ve been affected by the toothfish fishery.”

The voyage was originally intended to be an international collaboration but COVID-19 has meant overseas scientists have been unable to travel. All those on the voyage have been tested for COVID-19 ahead of departure as part of an international effort to keep Antarctica virus-free.

NIWA has also purchased a COVID testing machine that will be used on board if anyone displays symptoms.

This is the 14th Antarctic voyage for Tangaroa and Dr O’Driscoll’s fourth. He is particularly looking forward to studies of the animals living on the seafloor around the coastal zones.

“We are not always close to the coast so scientifically it will be interesting as well as providing for great views. We will be looking at what’s there between 30m and 200m depths where we don’t have a lot of information so there’s the discovery aspect of it too.”

Dr O’Driscoll says anyone who has been to Antarctica knows it is an incredibly beautiful place that presents huge challenges in such a rugged and remote environment.

“It’s one of those experiences that is transformational. Any time you go to sea around New Zealand you see something different every day. But to do science work in an Antarctic environment is just stunning.”

A specialised ice pilot will be on board to guide Tangaroa through the sea ice which is likely to change on a daily basis. The crew also includes a ship doctor.

Tangaroa returns to Wellington on February 17.

Scientist spots shark sperm storage strategy

Scientist spots shark sperm storage strategy

Source: NIWA – National Institute of Water and Atmospheric Research

A NIWA researcher has found the first evidence that female deep sea sharks store sperm as a strategy to preserve the species and possibly avoid aggressive mating encounters.

Fisheries modeller Adele Dutilloy was keen to discover more about deep sea sharks in New Zealand waters which are considered at risk of the impact of fishing. She figured that because so little is known about them, it was possible that some wrong assumptions were being made about the size and maturity of the females.

Using specimens of longnose velvet dogfish, leafscale gulper sharks and smooth deep sea skate collected by NIWA research vessel Tangaroa on the Chatham Rise and in the sub-Antarctic, Ms Dutilloy compared measurements of the reproductive organs with other assessment methods which are more subjective.

“I also cut up parts of the oviducal gland which produces egg casings and jelly to protect the egg and the foetus. In other species this gland has also been known to store sperm.” 

Thin sections of the gland were put on a microscope slide and stained. If sperm was present it would show up as dark blue, while the rest of the cell structure would be more purple.

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“I had lots of help trying to figure out what was sperm and what was other bits of cells. But as soon I was able to find one, it was actually quite easy to identify. I have to say though looking for sperm inside a cell is like looking for a needle in a haystack. It was incredibly exciting when I actually found it.”

While sperm storage is a relatively common strategy in some insects, bats, turtles and fish, this is the first time it has been documented in these species of deep sea sharks – Ms Dutilloy found sperm storage in three of the nine species she looked at it.

“It makes quite a lot of sense if our theories about the deep sea are true – that species are found in low numbers and they’re quite spread out, so they make the most of mating opportunities.”

If female sharks are not able to produce viable offspring when they mate, they may store sperm to use when they start ovulating – turtles go one step further and can decide which sperm to use to fertilise their eggs. And in some species of anglerfish the male fuses itself to the female, essentially acting as a sperm bank to increase the chances of reproductive success.

Ms Dutilloy says there may also be other explanations for female deep sea sharks storing sperm. “It might also be a strategy to reduce the need for more frequent mating events. Shark mating can be very aggressive resulting in bite wounds to the females.”

Sharks can also congregate in groups for mating where multiple males will mate with a single female. “It’s thought to be advantageous because it increases each male’s chances of passing on their genes to the next generation.”

Ms Dutilloy says it is not known how long sperm can be stored for but there are estimates of between 13 months and two years.

She is now hoping to investigate whether visual assessments of shark sexual maturity have been historically inaccurate and whether that matters.

“If our estimates of maturity are quite different to the reality, we think it might end up having quite a big impact on how we perceive that species and their resilience to fishing. If that’s the case, we need to find a better way of identifying a mature fish.“

She says when a fish is pregnant or bearing offspring may be a better gauge of the size of the reproductive adult population.

“This might give us a better idea of how resilient or how vulnerable a species is.”

Further information:

Adele Dutilloy
NIWA fisheries modeller
Contact Adele

This story forms part of our 2020 Summer Series. Check out more stories from the series.