Waiology

Dr Daniel Collins is a hydrologist at NIWA. He formed the Waiology blog to bring together commentary on New Zealand's freshwater systems. The blog features commentary from numerous contributors.

New ID key reveals freshwater invertebrates of Campbell Island - Waiology

Jul 09, 2014

By Shelley McMurtrie New Zealand’s subantarctic islands are a UNESCO World Heritage site of unparalleled beauty and outstanding natural values. One of these islands—New Zealand’s most southern landmass Campbell Island—is home to several globally rare species including its unique and colourful megaherbs, and one of the largest colonies of royal albatross. With an ever-increasing need to protect biodiversity values and understand how climate change will affect world ecosystems, the Subantarctic region is assuming increasing significance. However, our knowledge and understanding of the extensive freshwater ecosystems (streams, lakes, and tarns) of these remote islands is limited. Our newly published online identification key to the freshwater invertebrates of Campbell Island goes some way to bridging that information gap. Alex James (left) and Shelley McMurtrie (right) of EOS Ecology with Beeman Hill and Perseverance Harbour in the background. (Photo © S. McMurtrie)I … Read More

Using models to understand and protect our braided rivers - Waiology

Jun 23, 2014

By Murray Hicks Braided rivers, defined by networks of channels that are forever changing and shifting, are iconic features of the New Zealand landscape. Their existence depends on abundant supplies of gravelly sediment and frequent disturbance by floods and freshes. They also support unique communities of in-stream and terrestrial organisms (fish and birds) that have adapted to this dynamic physical environment. For example, the channel changes are sufficiently intense that riverbed weeds are naturally controlled, leaving bare gravel bars and islands which make relatively predator-safe habitats for river birds, including rare/endangered species such as the black stilt. There is concern, though, that water-use schemes that “de-energise” braided rivers by reducing the size and/or duration of flood flows– e.g. main-stem or tributary dams, or diversions into off-channel water storage reservoirs (collectively termed “flood harvesting”) – might alter the balance between vegetation … Read More

Citizen scientists help map Christchurch flooding - Waiology

Jun 16, 2014

By Daniel Collins The Christchurch earthquakes of 2010-2011 had a disastrous effect on Christchurch and its residents. But one effect could not be known until much later – flooding. The earthquakes changed the height of the ground across the city, raising or dropping the land by several 10s of centimetres in places. This meant that the flood risk maps we had of Christchurch were no longer as true as they used to be, and they needed to be updated. An opportunity to update the flood maps came when another disaster struck Christchurch. As an intense southerly moved up the country, many parts of the city were flooded, with water levels peaking between late morning and early afternoon on March 5, 2014. Homes were flooded and roads closed. But thanks to the widespread availability of camera phones, as well as our … Read More

New Zealand’s native freshwater fish are becoming increasingly threatened - Waiology

Jun 06, 2014

By Jane Goodman New Zealand’s native freshwater fish are becoming increasingly threatened The conservation status of New Zealand freshwater fish was assessed in June 2013 using the New Zealand Threat Classification System. The threat ranking lists are often misconstrued as being ‘owned’ by the Department of Conservation. However, although the listing exercise for all New Zealand taxa is the responsibility of the Department of Conservation, expert panels are made up of individuals from a broad range of organisations and should be referred to as New Zealand’s threat classification lists. Dusky galaxias (Galaxias pullus) – Nationally Endangered. (Credit: DOC, Coastal Otago) Lowland longjaw galaxias, Galaxias cobitinis – Nationally Critical. (Credit: DOC, Coastal Otago) The freshwater fish expert panel reviewed the status of 77 species, of which 54 are native residents. There has been a 9 percent increase in the … Read More

A helping hand for migrating fish - Waiology

May 23, 2014

By Paul Franklin and Sjaan Bowie Many of New Zealand’s iconic freshwater fish species, such as whitebait and eels, undertake migrations between the sea and freshwater as part of their life-cycle. Whitebait, for example, lay their eggs in freshwater or estuaries before the larvae move out to sea after hatching (Figure 1). After a number of months growing at sea, they then return to our rivers and streams and migrate upstream as the whitebait that New Zealanders love to catch and eat in their whitebait fritters! The ones that escape the whitebait nets and make it into our freshwater streams grow into adults before beginning the cycle all over again (Figure 1). Unfortunately, these movements are increasingly being obstructed by man-made structures commonly found in our rivers and streams, such as culverts (e.g. Figure 2), weirs, tide gates and dams. Read More

The value and values of water - Waiology

May 19, 2014

By Suzie Greenhalgh, Jim Sinner and Natasha Berkett The Land and Water Forum, the National Policy Statement for Freshwater Management and government proposals for further freshwater reforms all recognise the increasing competition between values for and uses of our freshwater resources in New Zealand. This competition has opened a new lexicon around what we mean by value and values and how these concepts are used in freshwater planning. There is a voluminous international literature on environmental values, and if anything is clear it is that this term is used in many different ways. In some contexts, values are ethical principles and guides to decision-making, such as kaitiakitanga, equity and efficiency. In other contexts, value refers to how well something contributes to a particular objective, e.g. swimming value means how good a river is for swimming. Value can also mean how … Read More

LAWA’s new environmental monitoring website clears up water quality data - Waiology

Apr 08, 2014

By Maree Clark and Kati Doehring The launch of LAWA (Land, Air, Water Aotearoa) last month is a significant milestone for our country’s environmental reporting. A web-based platform, LAWA displays state and trend information for more than 1100 freshwater monitoring sites throughout New Zealand in one place, and in an easy to understand format. It’s the first time you can look at data for a site, catchment, region or the country in one place and in a standardised way. It’s unique in that it allows everyone to learn about the state of our rivers, independently whether you’re a school child, scientist or policy maker. Making our science available to the public by communicating it in a jargon-free and easy-to-understand format is crucial. Everyone has the right to understand and know what’s going on in … Read More

World Water Day, 22 March - Waiology

Mar 21, 2014

By Daniel Collins Since 1993, March 22 has been World Water Day. Its purpose is to raise awareness of the importance of water to society and of the challenges people face in securing sufficient and safe water. Like many efforts run by the United Nations, it fosters collaboration between the economic and hydrologic haves and have-nots, and cooperation among riparian nations*. The water-energy nexus The theme for this year’s World Water Day is water and energy. Water is required to generate almost all forms of energy, and energy is needed to distribute and treat water. In New Zealand, a little over half of our electricity is generated renewably at hydropower stations, and even thermal power stations need water for cooling. Summer irrigation has also changed NZ’s profile of energy use, and even electricity prices affect how much … Read More

Calling for Christchurch flood photos - Waiology

Mar 07, 2014

By Daniel Collins The flooding that Christchurch experienced on Wednesday was extreme, leaving many houses flooded and roads closed. To build a better understanding of how vulnerable different parts of Christchurch are to flooding in the future, particularly following the earthquakes, we would like your help. If you took any photos at or near peak water levels anywhere in Christchurch during Wednesday morning or early afternoon, please send them to NIWA (floodphoto AT niwa.co.nz)* with the street address and time, and with the subject “Flood”. We will use the images to help identify how high the waters rose across the city. This will help us improve our models so we can provide better flood risk maps in the future. * The NIWA email is once again working. Sorry for any inconvenience. Update 16 June 2014: The … Read More

The colourful redfin bully - Waiology

Jan 06, 2014

By Amber McEwan As the temperatures gradually get warmer, we aren’t the only ones thinking about hopping into our local river. A small, yet spectacularly attractive little native fish called the redfin bully uses this time of year to make the move from the sea to fresh water. The male redfin bully is one of our most brightly coloured native freshwater fish (A. Perrie).The redfin bully is usually a freshwater fish but they undergo a migration when they are young. Adults lay eggs in streams and rivers and when they hatch, the tiny larvae are swept downstream and out to sea. They spend 3–6 months living in the sea (often travelling long distances with inshore currents!), then venture up into river mouths and begin to gradually make their way upstream. This is a kind of migration called diadromy … Read More