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BULL KELP - see synopsis below or go to Environmental Page


REPORT FROM U.S.A. - Aqua culture, re-seeding


Kelp Growing Plan a First



A valuable research trial is underway – directed by Dr Tim Haggitt PhD, and sponsored by Ocean Organics Ltd.

The intension and purpose of the research is to develop a sustainable harvesting strategy for the laminarian alga Ecklonia radiata.

Over a 2-3 year period, the research with specifically address:

  • Determining the standing stock of E. radiata for a given area of seabed
  • Quantifying the impacts of harvesting (cutting) natural populations
, including

a) regeneration of harvest areas

b) effect on other marine species.

This information will be used to:

  • Determine when E. radiata should not be cut and what size areas should be cut
  • Develop a harvesting / reseeding model for E. radiata.

The full scope of the trial is available to SANZ members on application.

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David I. Taylor, David R. Schiel  Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 1, New Zealand

ABSTRACT: Stands of the southern bull kelp Durvillaea antarctica (Chamisso) Hariot provide considerable biomass and a major habitat in the lower intertidal zone of exposed shores on the austral land masses. Whiplash effects of adult fronds (up to 10 m long) can affect recruitment, growth and survival of understorey species and potentially large brown algal competitors, thereby affecting community development. In southern New Zealand, D. antarctica is one of several species of large brown algae inhabiting the low intertidal zone. Effects of its canopy and its associated understorey coralline algae on community development were tested at 2 sites (Moeraki and Kaikoura) at different times of year between February 1999 and October 2001. Removal of D. antarctica canopies had surprising results compared to most studies where canopies of large brown algae were removed. The greatest initial recruitment of bull kelp occurred beneath intact canopies, usually in areas where corallines were removed. Recruitment was highly variable through time, with peaks occurring in June and October (austral winter–spring), depending mostly on when canopies were removed. There was an order of magnitude difference in recruitment between sites. The cover of turfing coralline algae, however, increased in all canopy removal treatments. A major source of mortality of young recruits was grazing by the herbivorous fish Odax pullus. Its distinct grazing marks were seen on recruits, almost exclusively outside the canopy of bull kelp where 80% of recruits were grazed. We show that D. antarctica has the ability to recruit beneath adult canopies, but that survival and growth ultimately depend on the extent of canopies, underlaying benthic algae and escapes from grazing by herbivorous fish.


Large brown algae dominate many marine rocky shores world-wide, providing biomass, food and biogenic habitat that support most inshore species.  Although many species of algae, particularly those of the order Fucales, are desiccation-resistant and occur throughout the intertidal zone, the large and dense stands usually begin along the intertidal–subtidal fringe (Stephenson & Stephenson 1972). Here, aerial exposure occurs only during the lowest of tides, but on high-energy shores, wave splash ameliorates this effect. As few of the species that occur at this fringe can survive either higher in the intertidal zone (cf. Schonbeck & Norton 1978) or lower in the subtidal zone (cf. Choat & Schiel 1982, Chapman 1995), this habitat is likely to be unique in the combination of processes that structure and maintain it. If this is the case, general models accounting for community structure (Menge et al. 1997) will require modification. Furthermore, a general understanding of structuring processes must include regional or global differences in the important taxa (Menge & Branch 2001).

One of the largest species of algae in the southern hemisphere occurs at the intertidal–subtidal fringe of exposed shores. The southern bull kelp Durvillaea antarctica (Chamisso) Hariot is abundant on most southern land masses at latitudes between 45 and 60° S including Tasmania, Chile, New Zealand and the sub-antarctic islands (Hay & South 1979, Santelices et al. 1980, Santelices 1990a). This species is the largest member of the order Fucales (Hurd 2000) and is surpassed in size only by a few of the largest laminarian algae. Fronds of this species can reach 10 m in length, while their biomass reaches up to 80 kg m–2 (Santelices et al. 1980, D.R.S. unpubl. data). Its positive effects on communities include the provision of habitat for grazing invertebrates that reside in and around hold fasts of adult plants (Hay 1977, Santelices 1990a, Edgar & Burton 2000). For example, Edgar & Burton (2000) found 23 macro-invertebrate taxa associated with D. antarctica holdfasts on the subantarctic Heard Island.

However, D. antarctica can also reduce or eliminate other species through the whiplash effects of its fronds (Santelices et al. 1980), leaving only a few species of tough foliose and coralline algae intact near canopies of D. antarctica.  Unlike Chile, however, where most of the potentially competing species are laminarian algae, particularly the tough Lessonia nigrescens (Santelices et al. 1980, Santelices & Ojeda 1984, Santelices 1990a), southern New Zealand has a rich flora of fucalean species as well as a wide variety of red algae in the lowest intertidal zone (Naylor 1953, Hay 1977, Schiel 1990, Nelson 1994, Schiel et al. 1995). Durvillaea antarctica occurs almost exclusively at exposed, outer coast sites, occasionally intruding into semi-exposed areas (such as behind headlands), but never into sheltered areas (Santelices 1990a, Taylor & Schiel 2003). There are usually few other foliose algae present, except hardy turfing coralline and other red algae, in the vicinity of adult bull kelp. Recruitment can be extensive. In southern New Zealand, Hay & South (1981) found that dense recruitment occurred in patches where plants were removed. This tended to be seasonal because in southern New Zealand, D. antarctica reproduces during austral autumn and winter (April to September) (Hay 1977) and greatest recruitment occurs during late winter–early spring.

Algal canopies can affect spore dispersal, light and nutrient supply to areas below, and the whiplash of fronds and the extensive areas occupied by holdfasts can pre-empt successful recruitment (Kennelly 1983, Dayton et al. 1984, Santelices & Ojeda 1984, Schiel & Foster 1986, Foster & Schiel 1987, Schiel 1988, 1990, Santelices 1990b, Connell 2003a). Consequently, large brown algae often recruit poorly beneath adult canopies compared to gaps outside them. For example, Santelices & Ojeda (1984) found that canopy effects and grazing combined to inhibit recruitment of Lessonia nigrescens Bory in central Chile. For multi-species assemblages, however, much of our understanding of the effects of large brown algae canopies comes from subtidal studies. For example, Dayton et al. (1984) followed demographic patterns of populations in southern California over a 10 yr period, removed canopies and seeded areas with sporogenic material of several algal species. They found a dominance hierarchy for light competition determined by adult canopy height, but a trade-off in the ability of higher canopies to withstand wave stresses. Of overriding importance, however, were the life-history constraints such as dispersal abilities and growth rates that determined the ability of each species to invade and persist under canopies of other algal species.

The relationship between recruitment of large brown algae and the corallines that occur beneath them is unclear. Coralline algae, a common feature of the understorey in lower intertidal and subtidal habitats, have been found both to inhibit the recruitment of some species and facilitate others (Connell 2003a,b). For example, Camus (1994) suggested that encrusting coralline algae reduced recruitment of Lessonia nigrescens in northern Chile by shedding epithallial cells. In other studies, turfing corallines facilitated recruitment of fucoid algae by providing suitable micro-habitat conditions (Brawley & Johnson 1991, 1993, Benedetti-Cecchi & Cinelli 1992). Here, we seek to elucidate the structuring processes in one of the most dominant and extensive assemblages in southern New Zealand (Nelson 1994). We test the effects of Durvillaea antarctica canopies, understorey corallines and the influence of different timing of disturbances on algal community development. These are then discussed with reference to the prevailing understanding of these processes in other related assemblages.


Note:  The materials and methods section is available as part of the full paper, also the intra-specific and interspecific sections - full paper PDF click here. 


Overall, Durvillaea antarctica appears to dominate these highly disturbed environments by arriving and recruiting in great numbers near adult canopies. We found that this is most likely to occur when free space occurs during winter and, because of winter storms, this is the time when free space is most readily available.

The whiplash effects of D. antarctica canopies appears to modify the understorey community by suppressing understorey turfing coralline algae and excluding all other species of large brown algae.

References available as part of full paper.

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Bull Kelp- From filaments to fish food for a habitat-forming alga

David Taylor, Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand, email: david.taylor@canterbury.ac.nz

"My research has explored some of the processes determining its distribution along intertidal shores.  In particular, I have examined factors affecting the growth and survival of different life stages across gradients of wave exposure." 

Click here to read the paper  Bull Kelp - David Taylor  (Environmental Page)

IRL Research into seaweed farming

Article from Industrial Research Ltd website

9 January 2006

Scientists from Industrial Research and NIWA (The National Institute of Water and Atmospheric Research) have achieved the successful pilot scale production of seaweed from spores for the first time in New Zealand.

Many years of painstaking effort have gone into finding the best conditions for commercially growing red seaweed (Gigartina atropurpurea) in this country, Industrial Research scientist Ruth Falshaw says.

The seaweed spores are carefully put on three metre strings and placed in the clear blue waters of the Marlborough Sounds at the top of the South Island. Industrial Research has discovered several new and exciting polymers, such as agars, carrageenans and fucans from New Zealand seaweeds, but the issue is always obtaining commercial quantities of raw material.

Developing a seaweed farming industry, which does not compete as a commodity product but sells on added value is the project aim, Ruth Falshaw says. A whole new seaweed growing industry could spread to the mussel farms in the Marlborough Sounds if this project is successful.

“Our ultimate aim is to make high value pharmaceutical products. “I think the way we need to go is to add value. We’re not going to go far sending containers of seaweed overseas, we want to be looking at things like cosmetics, nutraceuticals and pharmaceuticals,” Ruth Falshaw says.

Industrial Research and NIWA want to develop a seaweed industry in New Zealand, but there have to be sufficient stocks available for commercialisation to proceed, she says. Once transferred, spores grow at a rate of around three millimetres per day and suffer little competition from other unwanted species.

Initial trials have been preparing red seaweed for food industry applications, as there is a ready made market for this area. Applications include use as thickening and stabilising products, and use in the medical area is also being explored.

“I have people overseas who are interested in buying this material, but they need to know that there is a sustainable, reliable harvest before they can consider buying it,” Ruth Falshaw says. “We are just on the cusp on moving to a commercialisation phase for this.”

The quality of the New Zealand product is comparable to that received from South America, commercial tests have shown. Seaweed aquaculture is widespread in the tropics, but little is undertaken in temperate areas. And in South America where they collect seaweed from the wild, they are at the mercy of what grows naturally.

“I have people in Ireland and the United States who say once we have 20 tonnes of seaweed available then come and talk to us,” Ruth Falshaw says.

Fellow Industrial Research scientist Susie Carnachan says one of key results of their research has been to discover that pruning seaweed twice in a season produces more biomass than pruning it just once. “The more you cut them back the more they grow.”

So far the scientists been successful at growing male and female plants, but have not been successful with tetrasporic (or non-sexual) plants and are continuing research in this area.

for more see  -  http://www.irl.cri.nz/newsandevents/innovate/farming-seaweed.aspx


Kelp growing plan a first

The success of an unusual New Plymouth experiment in kelp growing is
likely to open the way for major environmental projects along the New Zealand coastline.

The research project is proving that it is possible to artificially grow
kelp, which is among the most important sea-floor vegetation. Scientists are now growing the plant on dozens of specially made concrete blocks placed in strategic areas off New Plymouth.

When the vegetation has reached a suitable size, the blocks will then be
relocated to other parts of the Taranaki foreshore in an effort to create new kelp "forests" - perfect habitat for a wide range of marine life. "It's like a potted plant industry in a way," said oceanographer Peter McComb, in New Plymouth last week. We think it has real potential.
If this research project works, the results could have a very wide
application - from people transplanting the kelp to help enhance their favourite dive spots, to re-establishing it in coastal areas that have been devastated by storms."

The research project is the initiative of the joint venture Shell, Todd
and OMV which owns the Pohokura offshore gas field that is about to be developed in Taranaki. During the resource consent process for the project, concern was expressed that the construction of offshore production platforms and laying of pipelines would damage existing kelp
plantations in the area. At the joint venture's request, special
conditions were built into the consents requiring a kelp reseeding project. Once the Pohokura field has been developed, the concrete blocks carrying the young kelp will be placed on the sea floor in the area.

The project is being carried out by Hamilton-based marine consulting and
research company ASR Ltd in conjunction with the Pohokura field's operating company Shell Todd Oil Services. The Taranaki Regional Council, Department of Conservation, Niwa and Port Taranaki are also involved.

Dr McComb said research showed that kelp spores travelled distances of
no more than five metres, which meant that natural colonisation of the marine plant was a slow process. The project is experimenting whether this can be accelerated. Dozens of concrete blocks have been placed in an existing kelp forest near one of the islands off Port Taranaki, and
more have been placed among kelp off the Waiwhakaiho River. Dr McComb
said success has already been achieved at both areas. "The kelp is growing really well on the blocks - some of the juvenile plants are already more than 6cm high. The next step is to see if these blocks can now be relocated.

The project is also trialling artificial kelp seeding. More concrete
blocks were placed in large tanks at a paua farm at Port Taranaki, and after kelp was artificially stimulated into releasing spores, the blocks were then transferred on to the harbour floor. Unfortunately, an algal bloom occurred in the harbour some weeks ago and smothered the spores, Dr McComb said, and that part of the project had to start again. "But we know we did get a good spore release in the artificial seeding. So it looks like the project will come down to deciding which way is the most efficient - the natural seeding or the artificial way."

This spring, scientists also intend placing reproductive kelp into
crayfish pots and locating it on barren reefs off New Plymouth, to see if the plant is capable of naturally transferring to a new site. Dr McComb said research showed that there were no large kelp forests in the Pohokura area. Rather, there were numerous patches of it. "Kelp is a
really important primary producer in the ocean. It's like grass, in that
everything feeds on it. In areas where there are large kelp forests, there are 100 times the density of marine life species, because it
provides food, shelter and habitat."
  Taranaki Daily News, New Zealand

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REPORT FROM U.S.A. - Aqua culture, re-seeding

Rockweeds (Fucus spp.) and knotted wrack (Ascophyllum spp.) are two of the most commercially important seaweed species in the Northeast. Thousands of tons of these seaweeds are harvested each year for use as fertilizer, animal feed, packing material for the lobster and marine baitworm industries, and the extraction of algin. Several other countries have also expressed interest in harvesting large quantities of these species from the coast of Maine. With the possibility of increased harvesting activity, many are concerned about the effects of overharvesting.

Since Ascophyllum and Fucus are found mainly in open coastal and estuarine habitats, they are susceptible to over-harvesting. Robert Vadas, researcher at the University of Maine, is studying how knotted wrack and rockweeds colonize and attach themselves to rocks in order to determine the best harvesting methods, as well as appropriate rates and amount of harvesting, to avoid damaging the resource.

Vadas found that knotted wrack, which lives 20 to 25 years, should be cut 12 to 15 inches above the substrate where it is attached in order to maintain a healthy plant. If the plant is cut or broken too low, it does not regenerate well. He also discovered that knotted wrack does not "recruit" easily ( i.e., the zygotes or early stages of the plant do not stick well to rocks). This could help explain its inability to recolonize or reseed itself.

A species of rockweed (Fucus distichus subspecies evanescent) lives only two to five years and recruits much more readily. By comparing the recruitment and attachment mechanisms of knotted wrack zygotes to those of Fucus species and the effects of water movement on recruitment, this study could provide crucial information for reseeding denuded or overharvested shores.

University of New Hampshire (UNH) researchers Arthur Mathieson and Subhash Minocha are studying the kelps, another ecologically and commercially important group of seaweeds. These large brown algae provide substrata and cover for a host of marine organisms and are another important source of algin. UNH researchers are exploring the genetic basis for the inheritance of desired traits by the kelps Laminaria longicruris and Laminaria saccharine, information that is essential to their cultivation. In addition, these scientists are seeking to identify genetic markers for desirable traits, indicators that will aid in the selection of the strains most suitable for aquaculture.

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page last updated November 2005