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Open Journal of Marine Science, 2014, 4, 163-173
Published Online July 2014 in SciRes. http://www.scirp.org/journal/ojms
http://dx.doi.org/10.4236/ojms.2014.43016
How to cite this paper: Hau, L., Robertson, J. and White, W.L. (2014) Metals in New Zealand Undaria pinnatifida (Wakame).
Open Journal of Marine Science, 4, 163-173. http://dx.doi.org/10.4236/ojms.2014.43016
Metals in New Zealand Undaria pinnatifida
(Wakame)
Leo Hau, John Robertson, William Lindsey White*
Institute of Applied Ecology New Zealand, School of Applied Sciences, Auckland University of Technology,
Auckland, New Zealand
Email:* lwhite@aut.ac.nz
Received 8 May 2014; revised 16 June 2014; accepted 2 July 2014
Copyright © 2014 by authors and Scientific Research Publishing Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Abstract
Undaria pinnatifida, Wakame is a popular edible seaweed in its native Asia and was first recorded
in New Zealand in Wellington Harbor in 1987. It is classified as an unwanted species under the
Biosecurity Act 1993, but there is growing interest in harvesting this seaweed for human con-
sumption. The aim of this study was to evaluate the concentrations of metals in U. pinnatifida from
several locations (Marlborough Sounds and Wellington harbor) and across seasons. In brief, the
highest monthly mean concentration of metals found in New Zealand wild U. pinnatifida was Ca
(16.97g∙kg−1), K (48.48 g∙kg−1), Mg (9.47 g∙kg−1), P (12.05 g∙kg−1), Cr (1.04 mg∙kg−1), Cu (3.78
mg∙kg−1), Mn (14.61 mg∙kg−1), Ni (2.78 mg∙kg−1), Se (0.83 mg∙kg−1), Zn (35.03 mg∙kg−1), As (46.71
mg∙kg−1), Cd (2.91 mg∙kg−1), Hg (0.042 mg∙kg−1) and Pb (0.31 mg∙kg−1). These results showed that
New Zealand U. pinnatifida is a good source of the nutritionally important minerals calcium, mag-
nesium, potassium and phosphorus. They also contained trace amounts of minerals such as chro-
mium, copper, manganese, nickel, selenium and zinc. Contaminants such as arsenic, cadmium,
mercury and lead were found at very low, safe, levels.
Keywords
Metals, Undaria pinnatifida, Wakame
1. Introduction
The importance of health foods is becoming widely acknowledged and as a result the consumption of seaweed
in Western countries has gradually increased. Seaweeds have been employed as food and medicines for a long
period of time in many Asian countries such as Japan, Korea, China, Vietnam, Indonesia and Taiwan [1]. Sea-
weed is an excellent source of nutrients such as fiber, polyunsaturated fatty acids, vitamins, proteins, and miner-
L. Hau et al.
164
als [2]. Seaweeds bio-accumulate essential elements for example Cr, Ni, Se, Mg, Ca, K and Zn at higher rates
than terrestrial vegetation [3]. But seaweed can also contain non-essential elements, such as As, Pb Cd or Hg
due to environmental pollution [3]. In brief, metal uptake occurs in two steps: The first is passive uptake; a sur-
face reaction, where metals are absorbed by algal surfaces through electrostatic attraction to negative sites [4]
[5]. This is independent of factors which influence the metabolism such as temperature, light, pH or age of the
plant, but it is influenced by the relative abundance of elements in the surrounding water [4]. The second way
metals can be taken up into seaweeds is a slower active uptake in which metal ions are transported across the
cell membrane into the cytoplasm and is more dependent upon metabolic processes [4] [5].
Wakame, U. pinnatifida, is the most popular edible seaweed in Asia. It has a sweet flavour and is most often
served in soups and salads [6]. Japan Korea and China are the main suppliers and use the most U. pinnatifida and
related products and have already successfully developed cultivation techniques and commercialisation of U.
pinnatifida related products. The current aquaculture production is between 450,000 and 500,000 tonnes in Japan
and Korea respectively with China producing a few hundred tonnes [7]. The global harvest of wild U. pinnatifida
was 2742 tonnes in 2011 [8].
Raw Wakame contains substantial amounts of essential trace elements such as manganese, copper, cobalt, iron,
nickel and zinc, similar to Kombu (kelps from the Family Laminariaceae) and Hijiki (Sargassum fusiforme) [9].
Processed Wakame is used for various instant foods such as noodles and soups [6] [9]. The most common dried
Wakame product is made from blanched and salted Wakame which is washed with freshwater to remove salt, cut
into small pieces, dried in a flow-through dryer and passed through sieves to sort the different sized pieces [9] [10].
It has a long storage life and has a fresh green colour when rehydrated [6] [9]. In addition to human consumption
as a regular food item, there is growing interest of U. pinnatifida in the health food and pharmaceutical markets
[11]. U. pinnatifida has proved to be a very useful source of Fucoidan [12], a fucose-containing sulfated poly-
saccharide found in brown algae and proven to have numerous health benefits including: anticoagulant anti-
thrombotic, immunomodulation, anti-inflammation, antitumor/anti-proliferation/anticancer, angiogenesis, car-
dioprotection, antivirus, gastric mucosal protection and neuroprotection [13]. Antioxidant compounds such as
Fucoxanthin, have also been extracted from U. pinnatifida [14].
The population of U. pinnatifida has been extended by accidental introductions and translocations for aqua-
culture from China and to Atlantic France and Mediterranean France however most movement of U. pinnatifida
has been by unintentional introductions to Europe, USA, Australia, New Zealand, Mexico and Argentina [9] [15]
[16]. U. pinnatifida was first recorded in New Zealand in Wellington Harbor in 1987 [17] and were most likely
transported in the ballast of foreign fishing vessels [18]. At present, U. pinnatifida in New Zealand has been re-
ported from Great Barrier Island, Auckland (Waitemata Harbor), Coromandel, Tauranga, Gisborne, Napier, Port
Taranaki, Wellington and the Wellington region of Cook Strait in the North Island, in the Marlborough Sounds,
Nelson, Golden Bay, Kaikoura, Lyttelton, Akaroa, Timaru, Oamaru, Dunedin Harbor, Bluff in the South Island
and also from Stewart Island and the Snares Islands [18]. Unlike more tropical climates where there is signifi-
cant dieback in warm conditions, U. pinnatifida seems to persist year long in New Zealand waters [18].
In 2000 U. pinnatifida was classified as an unwanted species under the Biosecurity Act 1993 under section
164c [19]. However, by 2004 a policy was developed that allowed the commercial harvest of the seaweed in two
situations: where it was taken as a by-product of another activity, for example, the clearing of mussel farming
lines or as part of a control or eradication programme [19]. In 2010 the government reviewed the policy and al-
lowed the harvest of U. pinnatifida from artificial structures and farming in some defined areas which already
had high levels of infestation [20].
Given that U. pinnatifida is regularly consumed by humans and it is now able to be harvested or farmed as a
commercial product in some parts of New Zealand, it is important to examine the nutritional quality of this sea-
weed in New Zealand. This research focused on metals components in U. pinnatifida as these metals have been
shown to have impact on human health. Fourteen metals, Ca, K, Mg, P, Cr, Cu, Mn, Ni, Se, Zn, As, Cd, Hg and
Pb were investigated in this study.
2. Material and Methods
2.1. Sampling Sites
Sampling for this research focused on four different sites. U. pinnatifida was collected from two mussel farms
L. Hau et al.
165
from Port Underwood, South Island, New Zealand. The two farms were designated as PE 327 (41˚20'36.89''S,
174˚07'50.17''E) and 106 (41˚19'35.05''S, 174˚08'56.71''E) (Figure 1). Sampling of PE 327 was carried out on a
monthly basis from April to October 2011. Sampling of 106 was carried on monthly basis from July to October
2011. Every month six plants were collected from each farm. The license to harvest the U. pinnatifida was is-
sued by MAF Biosecurity New Zealand, Biosecurity Act 1993 Section 52 Permission granted to Wakatu Sea-
foods Ltd.
The two additional sites were integrated into this study from August to November 2011. They were located on
the eastern and western side of Miramar Peninsula in Wellington Harbour, New Zealand. The eastern sampling
site was designated as Wellington site A, located in Shelley Bay (41˚17'38.082''S, 174˚49'16.110''E), the western
sampling site is designated as Wellington site B, located in Worser Bay (41˚18'46.207''S, 174˚49'49.678''E)
(Figure 1). Six replicate plants were collected from each farm. The license to harvest the U. pinnatifida was is-
sued by MAF Biosecurity New Zealand Biosecurity Act 1993 Section 52 Permission granted to Sustainable
Seafood NZ Ltd.
2.2. Seaweed Pre-Treatment
The samples collected from PE 327 and 106 were rinsed to remove debris and epiphytic organisms from the
thallus. The blade was separated from the sporophyll, frozen, lyophilized, ground to a fine powder and stored in
polyethyene bottles to await analysis.
The samples collected from Wellington harbor were rinsed to remove debris and epiphytic organisms from
the thallus. The blades were separated from the sporophylls. The samples were dried to constant weight at 60˚C
in a Sanyo MOV-112 laboratory oven, ground to fine powder and stored in polystyrene bottles to await analysis.
2.3. Metals Analysis
In brief, the dried, ground samples of U. pinnatifida were digested in acid, filtered, diluted and measured on a
Varian Liberty ICP AX Sequential inductively coupled plasma atomic emission spectroscopy (ICP-AES). Acid
digestions were carried out by adding an 0.5 g of sample to 10 mL of concentrated Laboratory Analytical Grade
70% HNO3 in acid digestion block (VELP Scientifica DK20 heating digester). The reaction mixture was heated
at 90˚C for 30 minutes and then 110˚C for 2 hours. 5 mL of 80% HClO4 was then added and heating discontin
ued when dense white fumes appeared. After cooling, the mixture was filtered through what man number 42 fil-
ter paper. The resulting solution was finally made up to 50 mL with deionized water in a volumetric flask. Each
blade and sporophyll sample from a single plant harvested was subjected to two replicate metals analysis expe-
riments. The ICP AES was running at Power of 1.2 kW, plasma flow at 15.0 L/min, auxiliary flow at 1.5 L/min,
nebulizer Pressure at 200 kPa, replicate time at 1 second, stability time of 15 seconds and PMT Voltage of
Figure 1. Location of Undaria pinnatifida samples.
L. Hau et al.
166
650 V. The ICP AES sample introduction settings was set at default, sample uptake of 30 seconds, rinse time of 10
seconds and pump rate at 15 rpm.
3. Results and Discussion
Our results demonstrate that U. pinnatifida contained variety of minerals and heavy metals and that these varied
in content across the time period investigated. Essential minerals for human health such as Ca, K, Mg and P
were the most abundant minerals while Cr, Cu, Mn, Ni, Se and Zn contents existed in trace amounts. Table 1
shows the range of metal contents of U. pinnatifida collected from four different sites in New Zealand.
Various agencies e.g. the World Health Organisation (WHO) and the National Health and Medical Research
Council of Australia (NHMRC) have recommended daily intake (RDI), upper level of intake (UI), tolerable
daily intake (TDI) and adequate intake (AI) for some of the metals in this study. In addition, the WHO has also
provided guidelines of provisional tolerable weekly intakes (TWI) for some of the more harmful heavy metals in
this study. We have determined the amount of each metal contained in an average serving of Wakame seaweed
salad. This is based on 40 g (wet weight) serving (approximately 4 g dry weight). These quantities are compared
to the WHO and NHMRC guidelines in Table 2. Mean data across all sites from October 2011 was used, be-
cause most metals displayed the highest concentration in that month and October is the most likely harvesting
period due to the large size of the plants at that time. A comparison of arsenic was not carried out because
available guidelines only govern inorganic arsenic levels, while total arsenic level was measured in this study.
3.1. General Patterns
There were significant differences between metal contents in the blade and sporophyll tissues, with the blade
generally containing higher concentration of metals than the sporophyll. This distribution may be able to be ex-
plained by the following mechanism. Absorption of elemental ions into the algal cells first occurred in the blade
when the division and enlargement of the cells occurred, and the elements can be secondarily transferred to the
sporophyll by active transport though inner hyphae in kelp species [20]-[22]. Therefore, the lower metal con-
centrations in the sporophyll can be explained by the difference of transfer tendency of the metals through the
transport system.
3.2. Calcium
There was an increase in the blade tissue content of calcium in 327 between May and June, and then it became
relatively stable. In general the blade tissue contents of Ca in 327 were slightly higher than the other three sites.
A similar pattern of fluctuations for the sporophyll tissue content of Ca had been observed for all four sites. PE
327 had slightly higher sporophyll tissue content of Ca than the other three sites. The blade values were compa-
rable with previous research of U. pinnatifida e.g. 12.8 g∙kg−1 from New Zealand [23], 9.31 g∙kg−1 recorded in
Spain [24] and 9.5 g∙kg−1. [25]. The World Health Organisation recommends the daily intake (RDI) of Ca is
between 1 g/day and 1.3 g/day for adult [26]. Whereas the nutrient reference values for Australia and New
Zealand states that the upper level of intake (UI) for Ca is 2.5 g/day and the recommended daily intake for adult
is 1 g/day [27].The Australia/New Zealand food standards code suggests the Care commended dietary intake for
adult is 0.8 g [28]. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Under-
wood would contribute 2.8% and 3.6% of the RDI by WHO/FAO and NHMRC respectively while the same
sample from Wellington would contribute 3.1% and 4.1% of the RDI by WHO/FAO and NHMRC respectively.
3.3. Potassium
There were steady increases of blade content of potassium in PE 327 from April to October, a similar trend also
observed along the sampling period in farm 106 and both Wellington sites between August and October. A sim-
ilar pattern of fluctuations of the sporophyll tissue content of K had been observed for all four sites but the spo-
rophyll content of K in 106 had noticeable lower concentration than the other three sites. The blade values were
lower than in previous research e.g. 71.2 g∙kg−1 from New Zealand [23], 86.99 g∙kg−1 recorded in Spain [24] and
56.91 g∙kg−1 [25]. The World Health Organisation do not have a recommended intake of K but the nutrient ref-
erence values for Australia and New Zealand states that the adequate intake (AI) for K is 2.8 g/day and 3.8g/day
for adult women and men respectively [27]. Consumption of 40 g (wet weight) U. pinnatifida obtained in October
L. Hau et al.
167
Table 1. Metal contents of Undaria pinnatifida collected from four different sites in New Zealand (see methods for loca-
tions). Values are the range of the monthly means ± standard error (n = 6). Sampling months are indicated by superscript
numbers (Jan = 1, Feb = 2, etc.).
Metal Site Blade Sporophyll
Ca (g∙kg−1) PE 327 9.77 ± 0.1484 - 16.97 ± 0.456 7.88 ± 0.244 - 8.75 ± 0.356
106 8.26 ± 0.088 - 9.07 ± 0.3410 6.37 ± 0.137 - 7.03 ± 0.3910
Wellington Site A 8.89 ± 0.178 - 10.13 ±0.2010 6.72 ± 0.178 - 7.03 ± 0.05510
Wellington Site B 8.76 ± 0.208 - 10.31 ± 0.4010 7.20 ± 0.398 - 7.41 ± 0.2310
K (g∙kg−1) PE 327 19.42 ± 0.265 - 45.86 ± 0.9110 27.25 ± 0.275 - 28.69 ± 0.866
106 32.85 ± 0.338 - 42.14 ± 0.5910 15.18 ± 0.547 - 16.10 ± 0.4410
Wellington Site A 29.49 ± 0.628 - 44.68 ± 0.5210 27.12 ± 0.887 - 28.97 ± 0.2910
Wellington Site B 27.92 ± 0.628 - 48.48 ± 0.5610 26.21 ± 0.4911- 27.08 ± 0.5210
Mg (g∙kg−1) PE 327 6.83 ± 0.144 - 9.21 ± 0.3610 4.58 ± 0.364 - 6.64 ± 0.3210
106 8.20 ± 0.167 - 9.47 ± 0.3110 5.75 ± 0.0458 - 6.16 ± 0.3710
Wellington Site A 8.34 ± 0.328 - 9.23 ± 0.3310 5.45 ± 0.1411- 5.72 ± 0.118
Wellington Site B 8.26 ± 0.218- 9.47 ± 0.2210 7.30 ± 0.228 - 7.59 ± 0.1410
P (g∙kg−1) PE 327 9.28 ± 0.197 - 12.05 ± 0.2310 7.89 ± 0.165 - 9.41 ± 0.3010
106 10.41 ± 0.197 - 11.62 ± 0.2610 6.60 ± 0.427 - 7.76 ± 0.7310
Wellington Site A 9.09 ± 0.198 - 10.31 ± 0.6610 8.24 ± 0.05311- 8.54 ± 0.1310
Wellington Site B 8.60 ± 0.438 - 10.61 ± 0.4310 7.99 ± 0.168 - 8.71 ± 0.1110
Cr (mg∙kg−1) PE 327 0.69 ± 0.0944 - 1.04 ± 0.2110 0.76 ± 0.0654 - 0.92 ± 0.0246
106 0.74 ± 0.0778 - 0.78 ± 0.0537 0.70 ± 0.0279 - 0.77 ± 0.0167
Wellington Site A 0.80 ± 0.0939 - 0.84 ± 0.02010 0.68 ± 0.0318 - 0.74 ± 0.02610
Wellington Site B 0.64 ± 0.0608 - 0.73 ± 0.02910 0.57 ± 0.0611 - 0.69 ± 0.01910
Cu (mg∙kg−1) PE 327 3.08 ± 0.167 - 3.78 ± 0.2310 1.64 ± 0.169 - 1.85 ± 0.117
106 2.97 ± 0.227 - 3.77 ± 0.2310 1.84 ± 0.0928 - 2.44 ± 0.1610
Wellington Site A 2.28 ± 0.218 - 2.62 ± 0.1510 2.21 ± 0.108 - 2.40 ± 0.1210
Wellington Site B 2.48 ± 0.279 - 2.66 ± 0.1210 2.33 ± 0.0919 - 2.64 ± 0.1110
Mn (mg∙kg−1) PE 327 8.73 ± 0.587 - 10.39 ± 2.4510 4.79 ± 0.267 -7.72 ± 0.854
106 8.25 ± 0.678 - 9.99 ± 1.2610 5.59 ± 0.387 - 6.26 ± 0.4010
Wellington Site A 12.57 ± 0.789 - 14.61 ± 1.2310 6.86 ± 0.5911 - 7.68 ± 0.2410
Wellington Site B 8.36 ± 0.1711- 8.57 ± 0.1910 7.46 ± 0.2811 - 7.93 ± 0.1310
Ni (mg∙kg−1) PE 327 1.54 ± 0.394 - 2.78 ± 0.1210 1.14 ± 0.165 - 1.62 ± 0.354
106 1.81 ± 0.137 - 2.24 ± 0.1210 1.36 ± 0.0458 - 1.62 ± 0.1810
Wellington Site A 1.78 ± 0.1111 - 1.95 ± 0.06710 1.50 ± 0.07811 - 1.69 ± 0.0568
Wellington Site B 1.91 ± 0.128 - 2.10 ± 0.05710 1.53 ± 0.2711 - 1.70 ± 0.05010
Se (mg∙kg−1) PE 327 0.54 ± 0.0174 - 0.61 ± 0.01610 0.18 ± 0.01736 - 0.33 ± 0.0307
106 0.40 ± 0.027 - 0.53 ± 0.05610 0.37 ± 0.0419 - 0.40 ± 0.02110
L. Hau et al.
168
Continued
Wellington Site A 0.80 ± 0.0499 - 0.83 ± 0.148 0.48 ± 0.03911 - 0.52 ± 0.039
Wellington Site B 0.65 ± 0.118 - 0.81 ± 0.07810 0.38 ± 0.038 - 0.48 ± 0.02510
Zn (mg∙kg−1) PE 327 20.52 ± 1.635 - 26.11 ± 2.7110 14.18 ± 1.285 - 18.60 ± 0.9210
106 22.60 ± 0.767 - 27.30 ± 2.7810 21.16 ± 1.708 - 23.60 ± 2.3310
Wellington Site A 30.24 ± 1.649 - 33.39 ± 3.9910 13.70 ± 1.068 - 15.41 ± 0.5310
Wellington Site B 29.41 ± 1.669 - 35.03 ± 2.0510 15.10 ± 1.0311 - 16.01 ± 0.4910
As (mg∙kg−1) PE 327 40.54 ± 2.0010 - 46.71 ± 0.755 23.84 ± 1.494 - 29.47 ± 1.757
106 30.41 ± 1.528 - 31.89 ± 2.227 23.94 ± 1.458 - 29.23 ± 2.277
Wellington Site A 34.79 ± 2.2511 - 42.88 ± 2.568 28.46 ± 5.8710 - 32.84 ± 2.308
Wellington Site B 32.12 ± 1.7711 - 36.41 ± 3.308 30.03 ± 2.408 - 31.27 ± 7.389
Cd (mg∙kg−1) PE 327 2.33 ± 0.2110 - 2.91 ± 0.0976 1.82 ± 0.2610 - 2.19 ± 0.175
106 1.57 ± 0.0888 - 1.74 ± 0.1910 1.51 ± 0.0598 - 1.68 ± 0.117
Wellington Site A 2.11 ± 0.139 - 2.24 ± 0.178 1.97 ± 0.2110 - 2.10 ± 0.178
Wellington Site B 1.82 ± 0.2911 - 2.21 ± 0.218 1.67 ± 0.3210 - 2.20 ± 0.49
Hg (mg∙kg−1) PE 327 0.023 ± 0.0155 - 0.040 ±0.0179 No values
106 0.024±0.00867 - 0.040± 0.00269 No values
Wellington Site A 0.021±0.0108 - 0.042± 0.02011 No values
Wellington Site B 0.021 ±0.00348 - 0.037 ± 0.02611 No values
Pb (mg∙kg−1) PE 327 0.22 ± 0.02410 - 0.29 ± 0.0444 0.14 ± 0.00474 - 0.29 ± 0.0485
106 0.24 ± 0.02210 - 0.30 ± 0.0197 0.21 ± 0.01510 - 0.27 ± 0.0177
Wellington Site A 0.28 ± 0.0189 - 0.31 ± 0.0228 0.23 ± 0.02610 - 0.25 ± 0.0169
Wellington Site B 0.25 ± 0.03211 - 0.29 ± 0.0299 0.167±0.02110 - 0.174±0.01678
ber from Port Underwood and Wellington would contribute 4.8% and 5.1% of the AI recommended by NHMRC
respectively.
3.4. Magnesium
There was an increasing trend for the blade tissue content of Mg in PE 327 between April and October. The
blade tissue contents of Mg from August to October were very similar between the four sites. There was also an
increasing trend between April and October for the sporophyll tissue content of Mg in PE 327. The other three
sites showed some fluctuations of sporophyll tissue content of Mg, in which Wellington B site had slightly
higher concentration than the other three sites between August and November. The blade values were similar to
what had been found in previous research of U. pinnatifida e.g. 8.33 g∙kg−1 [28] but lower than 11.81 g∙kg−1 [24].
World Health Organisation recommends the daily intake (RDI) of Mg were 0.22 g/day and 0.26 g/day for adult
women and man respectively. Whereas the nutrient reference values for Australia and New Zealand states that
the upper level of intake (UI) for adult Mg is 0.35 g/day and the RDI for adult is between 0.31 and 0.42 g/day
[27]. The Australia New Zealand food standards code suggests the Mg recommended dietary intake for adult is
0.32 g [28]. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Underwood and
Wellington would both contribute 9% of the NHMRCRDI.
3.5. Phosphorus
There were fluctuations without noticeable trend for the blade tissue content of phosphorus at all four sites. A
L. Hau et al.
169
Table 2. Consumption of 40 g (wet weight) of Undaria pinnatifida (blade tissues) obtained in October 2011. RDI = recom-
mended daily intake; AI = adequate intake; UI = upper level of intake; TDI = tolerable daily intake (per 70 kg body weight);
TWI = tolerable weekly intake (based on 70 kg body weight); WHO = World Health Organisation; FAO = Food and Agri-
culture Organisation of the United Nations; NHMRC = National Health and Medical Research Council of Australia.
Metal WHO/FAO
guidelines NHMRC
guidelines
% of WHO/FAO
guidelines
Port Underwood
% of NHMRC
guidelines
Port Underwood
% of WHO/FAO
guidelines
Wellington
% of NHMRC
guidelines
Wellington
Calcium (Ca) 1 - 1.3 g RDI 1 g RDI 2.8% of RDI 3.6% of RDI 3.1% of RDI 4.1% of RDI
Potassium (K) 2.8 - 3.8 g AI 4.8% of AI 5.1% of AI
Magnesium (Mg)
0.32 - 0.42 g
RDI
9% of RDI 9% of RDI
Phosphorus (P) 1 g RDI 4.8% of RDI 4.2% of RDI
Chromium (Cr)
0.025 - 0.035 mg
AI
11.8% of AI 9.6% of AI
Copper (Cu) 10 mg UI 0.15% of UI 0.11% of UI
Manganese (Mn) 5 - 5.5 mg AI 0.8% of AI 1.06% of AI
Nickel (Ni) 0.84 mg TDI 1.3% of TDI 1% of TDI
Selenium (Se)
0.026 - 0.034 mg
RDI
0.06 - 0.07 mg
RDI
7.1% of RDI 3.5% of RDI 9.5% of RDI 4.6% of RDI
Zinc (Zn) 8 - 14 mg RDI 0.78% of RDI 1% of RDI
Cadmium (Cd) 0.49 mg TWI 1.9% of TWI 1.8% of TWI
Mercury (Hg) 0.112 mg TWI 0.13% of TWI 0.12% of TWI
Lead (Pb) 1.75 mg TWI 0.054% of TWI 0.064% of TWI
similar pattern was also observed for the sporophyll tissue content of P. The blade values were higher than what
had been found in previous research of U. pinnatifida e.g. 4.79 g∙kg−1 [23] but lower than 4.50 g∙kg−1 [25]. The
nutrient reference values for Australia and New Zealand states that the upper level of intake (UI) of Pare 4 g/day
for adult between 19 to 70 years old and 3 g/kg for adult above 70 years old and the recommended dietary intake
(RDI) for adult is 1 g/day [27]. The Australia New Zealand food standards code suggests the P recommended
dietary intake for adult is 1 g [28]. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from
Port Underwood and Wellington would contribute 4.8% and 4.2% of the NHMRC RDI respectively.
3.6. Chromium
There was an increasing trend between April and June for the blade tissue content of chromium in PE 327, it
became relative stable until September and ended with another small increase in October. The blade tissue con-
tent of Cr from the other three sites showed some fluctuations across the sampling period. There was also an in-
creasing trend between April and June for the sporophyll tissue content of Cr in farm PE 327, which became
relative stable to the end of its sampling period. The sporophyll tissue contents of Cr in the other three sites were
steady across the sampling period. The blade values were similar to previous research e.g. 0.74 mg∙kg−1 [23] and
0.72 mg∙kg−1 [25]. The nutrient reference values for Australia and New Zealand states that the adequate intake
(AI) is 0.035 mg/day and 0.025 mg/day for adult men and women respectively [27].The Australia New Zealand
food standards code suggests the Cr estimated safe and adequate daily dietary intake recommended for adult is
0.2 mg [28]. Therefore consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Un-
derwood and Wellington would contribute 11.8% and 9.6% of the NHMRC recommended AI respectively.
3.7. Copper
The blade tissue contents of copper in the sites of Port Underwood were similar to each other and were higher
than the Wellington sites. There was a decreasing trend of the blade tissue content of Cu between April and July
in farm PE 327, and the trend became positive between July and October. The blade tissue content of Cu in the
other three sites had small fluctuations but were relative stable cross the sampling period. The sporophyll tissue
L. Hau et al.
170
content of Cu from all four sites showed some fluctuations across the sampling period with no noticeable trend
observed. The blade values were lower than in previous research e.g. 9.76 mg∙kg−1 [23] but high than 1.8
mg∙kg−1 [25]. The nutrient reference values for Australia and New Zealand state that the upper level of intake
(UI) for adult of Cu is 10 mg/day and the AI is 1.7 and 1.2 mg/day for adult men and women respectively [27].
Therefore consumption of less than 1 kg of wild U. pinnatifida would enough to delivery adequate amount of Cu
to human. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Underwood and
Wellington would contribute 0.15% and 0.11% of the NHMRC recommended UI respectively.
3.8. Manganese
There were small fluctuations for the blade tissue content of manganese across all four sites across the sampling
period. The blade from Wellington site A had higher Mn content than the other three sites while both Wellington
sites were higher in the sporophyll. The blade values were comparable to previous research e.g. 10.1 mg∙kg−1 [23]
and 8.7 mg∙kg−1 [24]. The Australia New Zealand food standards code for Mn states estimated safe and adequate
daily dietary intake recommended for adult is 5 mg [28]. The nutrient reference values for Australia and New
Zealand states that the adequate intakes (AI) are 5.5 mg/day and 5 mg/day for adult men and women respec-
tively [27]. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Underwood and
Wellington would contribute 0.8% and 1.06% of the NHMRC recommended Ai respectively.
3.9. Nickel
In farm PE 327, there was a steady increase of the blade tissue content of nickel between April and June, which
was followed by small drop between June and July, and ended with another small increasing trend. The blade
tissue contents of Ni in Port Underwood sites were slightly higher than sites from Wellington. The sporophyll
tissue contents of Ni in all four sites were relatively stable with some fluctuations and no noticeable trend. The
blade valueswere similar to previous research e.g. 2.65 mg∙kg−1 [25]. The World Health Organisation/Food and
Agriculture Organization of the United Nations (WHO/FAO) state that the Ni tolerable daily intake (TDI) is 12
µg/kg of body weight [29]. Assuming an adult with 70 kg the level would be 0.84 mg per 70 g person per day.
Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Underwood and Wellington
would contribute 1.3% and 1% of the WHO/FAO recommended TDI respectively.
3.10. Selenium
The blade tissue contents of selenium in all four sites showed patterns of fluctuation. The blade and sporophyll
from Wellington had higher Se content than Port Underwood. The blade values were higher than what had been
found in previous research e.g. 0.070 mg∙kg−1 [23] and 0.5 mg∙kg−1 [25]. The World Health Organisation has
RDI for adult of Se are 0.026 and 0.034 mg/day respectively for adult women and men [26]. Whereas the nu-
trient reference values for Australia and New Zealand states that upper level of intake (UI) for adult of Se is 0.4
mg/day and the recommended daily intake (RDI) are 0.06 and 0.07 mg/day for women and men respectively
[27].The Australia New Zealand food standards code suggests the Se recommended dietary intake for adult is
0.07 mg [28]. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Port Under wood
would contribute 7.1% and 3.5% of the WHO/FAO and NHMRCRDI respectively while seaweed from Wel-
lington would contribute 9.5% and 4.6%respectively
3.11. Zinc
The blade tissue contents of zinc in all four sites showed small fluctuations. Wellington sites had slightly higher
content of blade tissue Zn than Port Underwood sites. The sporophyll tissue content of Zn in all four sites also
showed small fluctuations. Site 106 had slightly higher sporophyll tissue content of Zn than the other three sites.
The blade values differed from previous research e.g. 22.9 mg∙kg−1 [23], 17.4 mg∙kg−1 [24] and 9.44 mg∙kg−1
[25]. The nutrient reference values for Australia and New Zealand states that the upper level of intake (UI) for
Zn is 40 mg/day and the recommended daily intake (RDI) is 14 and 8 mg/day for adult men and women respec-
tively [27]. The Australia New Zealand food standards code suggests the Zn recommended dietary intake for
adult is 12 mg [28]. Consumption of 40 g (wet weight) of U. pinnatifida obtained in October from Post Under-
wood and Wellington would contribute 0.78% and 1% of the NHMRCRDI respectively.
L. Hau et al.
171
3.12. Arsenic
The blade tissue content of arsenic between May to October in farm PE 327 showed a slow decreasing trend and
a similar trend also been noticed in Wellington Site A between August and November. The blade tissue content
of As from the other two sites showed small fluctuations and were relatively stable during their sampling period.
The sporophyll tissue content of As between April and July in farm PE 327 showed a slow increasing trend and
small fluctuations had been identified in the other three sites. The blade values differed from previous research
e.g. 35.62 mg∙kg−1 [23] and seaweed product in Spain contained total As could ranged from 0.031 - 149 mg∙kg−1
[30]. Marine algae could contain high levels of arsenic, but most were bound into organic molecules such as ar-
senosugars, which were not acutely toxic like the inorganic forms [31]. In New Zealand, the only regulation ap-
plying to seaweed foods is inorganic arsenic. In the New Zealand Food Standards Code, the limit for inorganic
arsenic in seaweeds is 1 mg∙kg−1 where the material is adjusted to 85% moisture [32].However, there was no
evidence that consumption of organic arsenic at levels up to 50 mg/kg/bw per day, through high levels of sea-
food consumption had led to adverse effects [33]. Therefore, the total arsenic detected in seaweeds was unlikely
to contribute health problems.
3.13. Cadmium
Both the blade and sporophyll tissue contents of cadmium in all four sites showed small monthly fluctuations
with no clear trends identified. The blade values differed from previous research e.g. 0.13 to 1.9 mg∙kg−1
(Almelaet al., 2002) [34]. The World Health Organisation/Food and Agriculture Organization of the United Na-
tions (WHO/FAO) states that the Cd provisional tolerable weekly intake (TWI) is 7 µg/kg of body weight [35].
Assuming an adult with 70kg the level would be 0.49 mg per week. Consumption of 40 g (wet weight) of U.
pinnatifida obtained in October from Port Underwood and Wellington would contribute1.9% and 1.8% of the
WHO/FAO recommended TWI respectively.
3.14. Mercury
The blade tissue content of mercury in all four sites was very low. No statistical analyses performed for sporo-
phyll tissue content Hg as no reliable values recorded. The blade values were comparable to previous research
e.g. 0.03 mg/kg [23].The World Health Organisation/Food and Agriculture Organization of the United Nations
(WHO/FAO) states the Hg provisional tolerable weekly intake (TWI) is 1.6 µg/kg of body weight [36]. Assum-
ing an adult with 70 kg the level would be 0.112 mg per 70 g person per week. Consumption of 40 g (wet weight)
of U. pinnatifida obtained in October from Port Underwood and Wellington would contribute 0.13% and 0.12%
of the WHO/FAO recommended TWI respectively.
3.15. Lead
The blade tissue content of lead in all four sites showed small fluctuations across months. There was an increase
of the sporophyll tissue content of Pb level between April and May in farm PE 327, which leveled out for the
rest of the sampling period. The blade values differed from previous research e.g. 0.23 mg∙kg−1 [23] and 0.79
mg∙kg−1 [25]. The World Health Organisation/Food and Agriculture Organization of the United Nations (WHO/
FAO) states the Pb provisional tolerable weekly intake (TWI) is 25 µg/kg of body weight [37]. Assuming an
adult with 70 kg the level would be 1.75 mg per 70 g person per week. Consumption of 40 g (wet weight) of U.
pinnatifida obtained in October from Port Underwood and Wellington would contribute 0.054% and 0.064% of
the WHO/FAO recommended TWI respectively.
4. Conclusion
Despite its long coastline, there has historically been little seaweed utilisation in New Zealand [38] [39]. This is
likely to change with the availability of U. pinnatifida as a resource. This study investigated the metal contents
of U. pinnatifida harvested from New Zealand waters and found that U. pinnatifida is rich in Ca, Mg, K and P
with small amounts of Cr, Cu, Mn, Ni, Se and Zn. The concentrations of the above elements when compared to
World Health Organisation/Food and Agriculture Organization of the United Nations (WHO/FAO) guidelines
and nutrient reference values for Australia and New Zealand, show that U. pinnatifida is safe for human con-
L. Hau et al.
172
sumption and the results for As, Cd, Hg and Pb when compared with WHO/FAO guidelines show that New
Zealand U. pinnatifida contains no heavy metals in levels that would be of any concern.
References
[1] Barsanti, L. and Gualtieri, P. (2006) Algae: Anatomy, Biochemistry, and Biotechnology. Taylor & Francis, Boca Ra-
ton.
[2] MacArtain, P., Gill, C.I.R., Brooks, M., Campbell, R. and Rowland, I.R. (2007) Nutritional Value of Edible Seaweeds.
Nutrition Reviews, 65, 535-543.
[3] Rupérez, P. (2002) Mineral Content of Edible Marine Seaweeds. Food Chemistry, 79, 23-26.
[4] Besada, V., Andrade, J.M., Schultze, F. and González, J.J. (2009) Heavy Metals in Edible Seaweeds Commercialised
For Human Consumption. Journal of Marine Systems, 75, 305-313.
[5] Faizal Bin Wan Ishak, W.M. and Hamzah, S.S.B. (2010) Application of Seaweed as an Alternative for Leachate
Treatment of Heavy Metal. International Conference on Chemistry and Chemical Engineering, Kyoto, 1-3 August
2010, 232-235.
[6] Murata, M. and Nakazoe, J.I. (2001) Production and Use or Marine Algae in Japan. Japan Agricultural Research
Quarterly, 35, 281-290.
[7] FAO (2012) Species Fact Sheets Undaria pinnatifida. http://www.fao.org/fishery/species/2777/en
[8] FAO (2012) Statistical Query Results—Capture: Quantity.
http://www.fao.org/figis/servlet/SQServlet?file=/work/FIGIS/prod/webapps/figis/temp/hqp_351669566851
0879974.xml&outtype=html
[9] McHugh, D.J. (2003) A Guide to the Seaweed Industry FAO Fisheries Technical Paper 441.
http://www.fao.org/docrep/006/y4765e/y4765e00.HTM
[10] Watanabe, T. and Nısizawa, K. (1984) The Utilization of Wakame (Undaria pinnatifida) in Japan and Manufacture of
“Haiboshi Wakame” and Some of Its Biochemical and Physical Properties. Hydrobiologia, 116-117, 106-111
[11] Hwang, E.K., Gong, Y.G. and Park, C.S. (2012) Cultivation of a Hybrid of Free-Living Gametophytes between Unda-
riopsis peterseniana and Undaria pinnatifida: Morphological Aspects and Cultivation Period. Journal of Applied Phy-
cology, 24, 401-408.
[12] Mak, W., Hamid, N., Liu, T., Lu, J. and White, W.L. (2013) Fucoidan from New Zealand Undaria pinnatifida:
Monthly Variations and Determination of Antioxidant Activities. Carbohydrate Polymers, 95, 606-614
[13] Wijesinghea, W.A.J.P. and Jeon, Y.-J. (2012) Biological Activities and Potential Industrial Applications of Fucose
Rich Sulfated Polysaccharides and Fucoidans Isolated from Brown Seaweeds: A Review. Carbohydrate Polymers, 88,
13-20.
[14] Yan, X., Chuda, Y., Suzuki, M. and Nagata, T. (1999) Fucoxanthin as the Major Antioxidant in Hijikia fusiformis, a
Common Edible Seaweed. Bioscience, Biotechnology, and Biochemistry, 63, 605-607
[15] Zemke-White, W.L. (2004) Assessment of the Current Knowledge on the Environmental Impacts of Seaweed Farming
in the Tropics. In: Phang, S.M., Chong, V.C., Ho, S.C., Noraieni, M. and Sim, J.O.L., Eds., Marine Science in the New
Millennium: New Perspectives and Challenges, University of Malaya Maritime Research Center, University of Malaya,
465-475.
[16] Zemke-White, W.L. and Smith, J.E. (2006) Environmental Impacts of Eucheuma spp. Farming. In: Critchley, A.T.,
Ohno, M. and Largo, D.B., Eds., World Seaweed Resources, Degussa, Amsterdam.
[17] Hay, C.H. and Luckens, P.A. (1987) The Asian Kelp Undaria pinnatifida (Phaeophyta: Laminariales) Found in a New
Zealand Harbour. New Zealand Journal of Botany, 25, 329-332. http://dx.doi.org/10.1080/0028825X.1987.10410079
[18] Neill, K., Heesch, S. and Nelson, W. (2009) Diseases, Pathogens and Parasites of Undaria pinnatifida. Ministry of
Agriculture and Forestry, Wellington.
[19] MAF (2009) Review of the Undaria Commercial Harvest Policy. Ministry of Agriculture and Forestry, Wellington.
[20] MAF (2010) The Commercial Use of Undaria pinnatifida—An Exotic Asian Seaweed. Ministry of Agriculture and
Forestry, Wellington.
[21] Wu, C.Y. and Meng, J.X. (1997) Translocation of Assimilates in Undaria and Its Cultivation in China. Hydrobiologia,
352, 287-293.
[22] Kumura, T., Yasui, H. and Mizuta, H. (2006) Nutrient Requirement for Zoospore Formation in Two Alariaceous Plants
Undaria pinnatifida (Harvey) Suringar and Alaria crassifolia Kjellman (Phaeophyceae: Laminariales). Fisheries
Science, 72, 860-869. http://dx.doi.org/10.1111/j.1444-2906.2006.01228.x
L. Hau et al.
173
[23] Smith, J.L., Summers, G. and Wong, R. (2010) Nutrient and Heavy Metal Content of Edible Seaweeds in New Zealand.
New Zealand Journal of Crop and Horticultural Science, 38, 19-28. http://dx.doi.org/10.1080/01140671003619290
[24] Rupérez, P. (2002) Mineral Content of Edible Marine Seaweeds. Food Chemistry, 79, 23-26.
http://dx.doi.org/10.1016/S0308-8146(02)00171-1
[25] Kolb, N., Vallorani, L., Milanovic, N. and Stocchi, V. (2004) Evaluation of Marine Algae Wakame (Undaria pinnati-
fida) and Kombu (Laminaria digitata japonica) as Food Supplements. Food Technology and Biotechnology, 42, 57-61.
[26] WHO (2004) Vitamin and Mineral Requirements in Human Nutrition. 2nd Edition.
http://whqlibdoc.who.int/publications/2004/9241546123.pdf
[27] Anonymous (2005) Nutrient Reference Values for Australia and New Zealand Including Recommended Dietary In-
takes. National Health and Medical Research Council, Australia, Ministry of Health, New Zealand.
[28] FSANZ (2011) Australia New Zealand Food Standards Code 1.1.1. Issue 121, Food Standards Australia New Zealand.
[29] WHO (2005) Nickel in Drinking-Water. Background Document for Development of WHO Guidelines for Drinking-
Water Quality. World Health Organization, Geneva.
[30] Almela, C., Jesus Clemente, M., Velez, D. and Montoro, R. (2006) Total Arsenic, Inorganic Arsenic, Lead and Cad-
mium Contents in Edible Seaweed Sold in Spain. Food and Chemical Toxicology, 44, 1901-1908.
http://dx.doi.org/10.1016/j.fct.2006.06.011
[31] Andrewes, P., Demarini, D., Funasaka, K., Wallace, K., Lai, V., Sun, H., Cullen, W. and Kitchin, K. (2004) Do Arse-
nosugars Pose a Risk to Human Health? The Comparative Toxicities of a Trivalent and Pentavalent Arsenosugar. En-
vironmental Science &Technology, 38, 4140-4148. http://dx.doi.org/10.1021/es035440f
[32] FSANZ (2011) Australia New Zealand Food Standards Code 1.4.1. Issue 121, Food Standards Australia New Zealand.
[33] COT (2003) Statement on Arsenic in Food: Results of the 1999 Total Diet Study.
http://cot.food.gov.uk/pdfs/ArsenicStatement.PDF
[34] Almela, C., Algora, S., Benito, V., Clemente, M.J., Devesa, V., Suner, M.A., Veälez, D. and Montoro, R. (2002)
Heavy Metal, Total Arsenic, and Inorganic Arsenic Contents of Algae Food Products. Journal of Agricultural and
Food Chemistry, 50, 918-923. http://dx.doi.org/10.1021/jf0110250
[35] WHO (2003) Cadmium in Drinking-Water. Background Document for Preparation of WHO Guidelines for Drinking-
Water Quality. World Health Organization, Geneva.
[36] JECFA (2004) Evaluation of Certain Food Additives and Contaminants: Sixty-First Meeting of the Joint FAO/WHO
Expert Committee on Food Additives. World Health Organization, Geneva.
[37] WHO (2003) Lead in Drinking-Water. Background Document for Preparation of WHO Guidelines for Drinking-Water
Quality. World Health Organization, Geneva.
[38] Zemke-White, W.L., Bremner, G. and Hurd, C.L. (1999) The Status of Commercial Algal Utilisation in New Zealand.
Hydrobiologia, 137, 487-494. http://dx.doi.org/10.1023/A:1017064303131
[39] Zemke-White, W.L., Speed, S.R. and McClary, D.J. (2005) Beach-Cast Seaweed: A Review. New Zealand Fisheries
Assessment Report 2005/44, Ministry of Fisheries, Wellington.
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