Rhodolith Beds in Northern New Zealand: Characterisation of Associated Biodiversity
Citation
Nelson, W.A.; Neill, K.; Barr, N.; D'Archino, R.; Miller, S.; Stewart, R. (2012). Data from: Rhodolith Beds in Northern New Zealand: Characterisation of Associated Biodiversity. Southwestern Pacific OBIS, National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand, 684 records, Online http://nzobisipt.niwa.co.nz/resource.do?r=rhodolithhabitats released on June 20, 2015. https://doi.org/10.15468/3zyorf accessed via GBIF.org on 2024-10-12.Description
The ecology of subtidal rhodolith beds has been investigated for the first time in New Zealand, characterising two rhodolith species, Lithothamnion crispatum and Sporolithon durum, examining the structure and physical characteristics of beds at two locations and documenting their associated biodiversity. Site and characteristics: Field work was conducted in the Bay of Islands, at Kahuwhera Bay and Te Miko Reef, in February and September 2010. The rhodolith beds were mapped using a combination of techniques and the physical characteristics of the habitats were assessed and compared with adjacent areas outside the rhodolith beds. The rhodolith beds differed significantly in terms of water motion, sediment characteristics and light levels, with Te Miko Reef having characteristics regarded as typical of rhodolith assemblages, and Kahuwhera Bay being atypical with respect to sediments and water clarity. The Te Miko Reef bed was in clear water and rhodoliths were clearly visible sitting on top of the substrate in a more or less single layer over rhodolith- and shell-derived gravel, whereas at Kahuwhera Bay there were fine sediments suspended in the water column and covering rhodoliths and associated biota, and live rhodoliths were in a more or less single layer overlaying grey to blackened rhodoliths in a darkly coloured rhodolith/sediment sublayer. The two rhodolith beds differed in current direction and strength with no clear tidal signal or direction of water motion at Kahuwhera Bay and tidally driven water movement at Te Miko Reef with a dominant northwest flow.
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Sampling Description
Study Extent
Two rhodolith beds within the Bay of Islands, northern New Zealand, were selected as the locations for the majority of the field work in this study. These beds were identified as potential study locations during earlier field work (ZBD2004-07; Bay of Islands OS20/20 project). Kahuwhera Bay, (35o 15’ 40.00” S, 174o 10’ 55.00” E) is situated on the southern side of the larger Manawaora Bay on the mainland, and Te Miko Reef (35° 13’ 43.80” S, 174° 10’ 55.00” E) lies 4 km to the north in the 0.7–1.2 km wide channel between Moturua Island and Motuarohia Island (Figure 2). Field work was carried out in February and September 2010, allowing late summer and early spring sampling of biological and physical data.Sampling
At each location, sites inside and outside the rhodolith beds were assessed (two sites at each location, i.e., Kahuwhera Bay - KWB and KWB_OUT, Te Miko Reef - TMR and TMR_OUT). At Te Miko Reef an additional site containing mixed rhodolith species was also assessed (TMR_B). As the beds were more or less at single depth (approximately 8 m), it was not necessary to stratify sampling by depth.Method steps
- At each site two 25 m transects were laid out at right angles to the anchor line, creating a single 50 m transect. On each transect, a random point quadrat (RPQ) (after Foster et al. 2007) was used at eight points, 5 m apart, to record the biogenic substrate type (rhodoliths, algae, microalgal mat and sponge/tunicate or bare substrate) under each of 10 knots. The point quadrat was a 1 m long bar with a 120 cm long string attached like a loose string on a bow. Five knots on the string were used as points and the organisms or substrate found on each side of the bar were sampled giving 10 points per quadrat (as detailed in Foster 1975). At sites within the rhodolith beds (i.e., KWB, TMR, TMR_B) all live rhodoliths and associated biodiversity from within a 25 by 25 cm quadrat were collected into plastic bags at each of the eight random points on the transect. These quadrat samples were tipped out into large plastic containers and then thoroughly sorted. All associated epibiota were removed and preserved appropriately for each taxon group for later identification to species level where possible. The rhodoliths were identified to 12 •Rhodolith beds in northern New Zealand Ministry for Primary Industries species, assessed for vitality (proportion of dead and live rhodoliths), and measured to obtain size frequency at each site. Rhodoliths were collected from both locations and transported to Wellington for experimental work on vulnerability to stressors (Objective 2). Infauna were assessed using a cylindrical 10 cm diameter by 10 cm depth core to remove substrate under each quadrat. A sample of sediment was kept from each core for subsequent grain size analysis (i.e., one sediment sample per quadrat). Core samples were sieved through a 5 mm mesh. All macrofauna (approximately 5 mm and above) were sorted to phylum and preserved appropriately for later identification to species level where possible.
Additional info
marine, harvested by iOBISTaxonomic Coverages
Geographic Coverages
Bibliographic Citations
- Nelson, W.A.; Neill, K.; Barr, N.; D'Archino, R.; Miller, S.; Stewart, R. (2012) .Rhodolith Beds in Northern New Zealand: Characterisation of Associated Biodiversity and Vulnerability to Environmental Stressors New Zealand Aquatic Environment and Biodiversity Report No. 99. ISSN 1179-6480 (online). ISBN 978-0-478-40077-9 (online) -
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Kevin Mackay
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Wendy Nelson
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