Mokohinau Islands Research Articles

Senecio pokohinuensis (Asteraceae), a new combination for an endemic species of Mokohinau Islands, Hauraki Gulf (Tikapa Moana o Hauraki), northern Te Ika a Maui / North Island, Aotearoa / New Zealand

Previous research has demonstrated that Senecio repangae subsp. repangae and subsp. pokohinuensis have independent evolutionary origins. Here, we therefore elevate subsp. pokohinuensis to species rank: Senecio pokohinuensis. Updated morphological descriptions for both species are also provided.

Impacts of near future sea surface pH and temperature conditions on fertilisation and embryonic development in Centrostephanus rodgersii from northern New Zealand and northern New South Wales, Australia

Oceans are warming and becoming more acidic. While higher temperature and lower pH can have negative effects on fertilisation and development of marine invertebrates, warming may partially ameliorate the negative effect of lower pH. This study determined the effect of warming (3 °C) and decreased pH (0.3, 0.5, 1.1 units below ambient) on fertilisation and development in two populations of the sea urchin Centrostephanus rodgersii, one at its northern range limit (Coffs Harbour, New South Wales NSW, 30°27′S, 153°14′E) and the other one in New Zealand where the species may be a recent arrival (Mokohinau Islands, 35°56′S, 175°9′E). Both populations were sampled in August 2011. The two populations exhibited a differential response to temperature, while pH affected them similarly. Fertilisation was robust to pH levels forecast for 2100, and it was only slightly reduced at pH values forecast for 2300 (i.e. ≈5 and ≈8 % for the northern NSW and the New Zealand populations, respectively). Decreased pH (pH = 7.6) reduced the percentage of succeeding developmental stages. Progression through cleavage and hatching stages was faster at +3 °C in the New Zealand population but not in northern NSW urchins, while for the NSW population, there was a positive interaction between temperature and pH at hatching. Gastrulation was negatively affected by an extreme pH 7.0 treatment (60–80 % reduction) and least affected by increased temperature. The percentage of abnormal embryos at gastrulation increased significantly at +3 °C treatment in the northern NSW population. Predicted future increases in temperature may facilitate further expansion of the geographical range of C.rodgersii in New Zealand, with a minimal effect of concurrent reduced pH.

Reproduction of the Diadematidae sea urchin Centrostephanus rodgersii in a recently colonized area of northern New Zealand

Reproduction of the sea urchin Centrostephanus rodgersii at the Mokohinau Islands (northeast New Zealand) was studied in terms of the gametogenetic cycle and sex ratio, and larval range of thermal tolerance was determined. A comparison with the reproductive patterns in populations located in New South Wales (NSW), the historical range of the species, and Tasmania, where the species has only recently arrived (≈ 50–60 years ago), was made. Results indicate that C. rodgersii in New Zealand is capable of growing gonads, completing a gametogenetic cycle and producing viable gametes. The timing of this process is similar to the population in Sydney (central NSW), where spawning is probably triggered by the winter solstice and lasts from July to September. The sex ratio was skewed towards females (1.6 females for each male), which may be indicative of the recent arrival of the species in New Zealand. Larvae obtained from this population were able to develop at a measurable rate after 72 h only between 16°C and 25°C. Ambient temperatures during spawning at the Mokohinau Islands (15.7–16.8°C) appear to be at the lower end of the range of temperatures suitable for early larval development.

Taxonomic revision of the marbled skink (Cyclodina oliveri, Reptilia: Scincidae) species complex, with a description of a new species

We have completed a taxonomic revision of the New Zealand marbled skink (Cyclodina oliveri) species complex. Morphological analyses and mitochondrial sequence data (ND2, ND4, Cytochrome b; Total 1933 bp) are used to describe a new taxon (commonly known as the “Mokohinau” skink) and redefine C. oliveri. The morphological and molecular data indicate that C. oliveri is distributed on the Poor Knights Islands, Mercury Islands and Aldermen Islands. The new species is restricted to the Mokohinau Islands, Hen and Chickens group, Little Barrier Island and Great Barrier Island. Our data demonstrate that there is no support for the separation of the Poor Knights Islands population of C. oliveri from those on the Mercury Islands and Aldermen Islands. The genetic data indicate that C. whitakeri is part of the C. oliveri species group. Divergence time estimates indicate that the C. oliveri species complex diverged during the late‐Miocene, with further divergences among island groups in C. oliveri including the origin of the new taxon during the late‐Pliocene and mid‐Pleistocene. We present a diagnostic key for Cyclodina.

A new location for the Poor Knights spleenwort (Asplenium pauperequitum, Aspleniaceae) on The Forty Fours, Chatham Islands, New Zealand

Documentation is made of the discovery of the Poor Knights spleenwort, (Asplenium pauperequitum) in a sample of vascular plant specimens collected from The Forty Fours. These islands are the easternmost outlier of the Chatham Islands archipelago. Hitherto this fern had been believed endemic to the Poor Knights Islands and Mokohinau Islands of the Hauraki Gulf, off eastern Northland, North Island, New Zealand. Frond and spore morphology together with chloroplast DNA sequences were used to confirm its identity. Whether this fern disjunction of some 1245 km is the result of vicariance or longdistance dispersal is discussed and long‐distance dispersal of fern spores or whole sporangia is considered most likely.

Cyperus insularis (Cyperaceae), a new species of sedge from northern New Zealand

Cyperus insularis Heenan et de Lange is described as a new species for plants that have previously been considered to be a northern variant of C. ustulatus. This new species is distinguished from C. ustulatus by a suite of floral and vegetative characters. These include grey‐green leaves and involucral bracts, light pink or light purple‐pink leaf sheaths, a uniformly green culm, the inflorescence rays usually branched, glumes and ray bracts green at flowering and drying yellow brown to light brown at fruiting, and longer spikes, anthers, and filaments. The chromosome number of C. insularis is 2n = 112–114. C. insularis occurs mainly on northern offshore islands, and appears to be the only species of Cyperus present on the Kermadec, Three Kings, Poor Knights, and Mokohinau islands, while it is sympatric with C. ustulatus on the Hen and Chickens Islands, Great Barrier Island, and at several mainland locations. A lectotype for C. ustulatus f. grandispiculosus is selected from the Carse Herbarium.

Rapid recolonisation of snapper Pagrus auratus: Sparidae within an offshore island marine reserve after implementation of no-take status

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 272:183-190 (2004) - doi:10.3354/meps272183 Rapid recolonisation of snapper Pagrus auratus: Sparidae within an offshore island marine reserve after implementation of no-take status Christopher M. Denny1,*, Trevor J. Willis2, Russell C. Babcock3 1Leigh Marine Laboratory, PO Box 349, Warkworth, New Zealand 2Laboratori Scienze Ambientali, Università di Bologna, Via Saint Alberto 163, 48100 Ravenna, Italy 3CSIRO Marine Research Floreat, Private Bag No. 5, Wembley, Western Australia 6913, Australia *Email: c.denny@auckland.ac.nz ABSTRACT: This study reports the response of snapper Pagrus auratus to the establishment of no-take status in a marine reserve around the Poor Knights Islands in northeastern New Zealand. The Poor Knights and 2 reference locations, Cape Brett and the Mokohinau Islands, were sampled biannually for 4 yr using baited underwater video (BUV). Following the implementation of full marine reserve status at the Poor Knights in October 1998, snapper showed significant increases in abundance and biomass relative to fished control locations. This was particularly apparent for large snapper (>270 mm), whose numbers increased rapidly to levels 7.4 times higher in the final survey compared to the initial pre-reserve survey, and total snapper biomass increased by 818%. There was no significant increase in the abundance, biomass or size of snapper at the reference locations over this time. There was a strong seasonal trend in snapper abundance, with higher numbers in autumn (March/April) compared to spring (September/October). The daily batch fecundity was 11 to 18 times higher at the Poor Knights compared to the reference locations. Once fishing ceased in previously partially protected areas, a rapid recovery of snapper ensued, suggesting that partial fishing regulations are ineffective for protecting targeted species. The speed of increase in snapper density resulted from the immigration of adult fish into the reserve, rather than from within-reserve recruitment. KEY WORDS: Baited underwater video · Poor Knights · Fishing · Partial protection · Temperate reefs · Temporal variation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 272. Online publication date: May 19, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Do partial marine reserves protect reef fish assemblages?

Fish assemblages in the Mimiwhangata Marine Park, an area closed to commercial fishing but open to most forms of recreational fishing, were compared with adjacent fished areas. Two survey methodologies were used; baited underwater video and underwater visual census. Snapper ( Pagrus auratus), the most heavily targeted fish species in the region, showed no difference in abundance or size between the Marine Park and adjacent control areas. When compared to the fully no-take Poor Knights Island Marine Reserve and two other reference areas open to all kinds of fishing (Cape Brett and the Mokohinau Islands), the abundance and size of snapper at the Marine Park were most similar to fished reference areas. In fact, the Marine Park had the lowest mean numbers and sizes of snapper of all areas, no-take or open to fishing. Baited underwater video found that pigfish ( Bodianus unimaculatus), leatherjackets ( Parika scaber) and trevally ( Pseudocaranx dentex) were significantly more common in the Marine Park, than in the adjacent control areas. However, none of these species are heavily targeted by fishers. Underwater visual census found similar results with five species significantly more abundant in the Marine Park and five species more abundant outside the Marine Park. The lack of any recovery by snapper within the Marine Park, despite the exclusion of commercial fishers and restrictions on recreational fishing, indicates that partial closures are ineffective as conservation tools. The data suggest fishing pressure within the Marine Park is at least as high as at other ‘fished’ sites.

Geographic variation in morphology and flavonoid chemistry in Hebe pubescens and H. bollonsii (Scrophulariaceae), including a new infraspecific classification for H. pubescens

Geographic variation in morphology, leaf anatomy, and flavonoid chemistry is appraised in Hebe pubescens, H. bollonsii, and allied plants from islands of outer Hauraki Gulf, North Island, New Zealand. The circumscription of H. pubescens is modified to include plants from Great Barrier, Little Barrier, and the Mokohinau Islands, as well as the Coromandel Peninsula and immediately surrounding islands. A new infraspecific classification is proposed for H. pubescens, wherein three subspecies are recognised. Subspecies pubescens occurs on the Coromandel Peninsula and immediately surrounding islands, and also at Papanui Point on the western coast of the Firth of Thames. Subspecies rehuarum occurs on Great Barrier Island. Subspecies sejuncta occurs primarily on the Mokohinau Islands and Little Barrier Island, with a single plant also known on Great Barrier Island. Populations of H. pubescens probably form a cline of variation, and some forms of subsp. sejuncta share morphological features with H. bollonsii, which is here considered restricted to the Poor Knights Islands, the Hen and Chickens Islands, and nearby areas of the Northland coast. Possible relationships of H. pubescens and H. bollonsii are discussed. A key to the taxa of Hebe pubescens is provided.

The vascular flora of Aorangi Island, Poor Knights Islands, northern New Zealand

An annotated vascular flora of 282 taxa for Aorangi Island, Poor Knights Islands, is presented. Additional records (20 taxa) from Tawhiti Rahi Island, the other major island in the archipelago, are listed separately, resulting in a combined Poor Knights vascular flora of 302 taxa. Two new combinations, Wahlenbergia littoricola subsp. vernicosa and Xeronema callistemon f bracteosa, are made for plants previously treated as W. vernicosa and X. callistemon var. bracteosa, respectively. Only one taxon, Xeronema callistemon f. bracteosa, is provisionally accepted as endemic to the Poor Knights Islands. The control of the more serious weed species on the island is discussed. A case is made for including the Mokohinau Islands within the Poor Knights Ecological Region.

Senecio repangae (Asteraceae): A new endemic species from the north‐eastern North Island, New Zealand

A new species Senecio repangae is described from the north‐eastern North Island, New Zealand, where it grows primarily on offshore islands. It has previously been included within the widespread New Zealand endemic Senecio lautus, from which it is distinguished by its much taller, sparingly branched habit, longer and narrower capitula, much shorter, widely and unevenly spaced, recurved, incised ray florets, and by its chromosome number (2n = 100). A new subspecies, S. repangae subsp. pokohinuensis, endemic to the remote Mokohinau Islands group is also recognised. This allopatric taxon is distinguished from S. repangae subsp. repangae by its sparsely hairy, glabrescent, glaucous, adaxial leaf surface, smaller involucral bracts, and evenly spaced, longer, ray florets which are never recurved. The distribution, ecology, cytology, reproductive biology, conservation, and relationships of both subspecies to other New Zealand Senecio species are assessed.

Scaling of ammonium uptake by seaweeds to surface area:volume ratio:geographical variation and the role of uptake by passive diffusion

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 169:143-148 (1998) - doi:10.3354/meps169143 Scaling of ammonium uptake by seaweeds to surface area:volume ratio:geographical variation and the role of uptake by passive diffusion Richard B. Taylor, Jeroen T. A. Peek, T. Alwyn V. Rees* Leigh Marine Laboratory, University of Auckland, PO Box 349, Warkworth, New Zealand *Addressee for correspondence. E-mail: ta.rees@auckland.ac.nz ABSTRACT: Rates of ammonium uptake per g dry weight for seaweeds from the Mokohinau Islands, northeastern New Zealand were much lower than published values for northern hemisphere (east coast of North America and Baltic Sea) seaweeds. For the New Zealand seaweeds, the rate of ammonium uptake expressed per cm2 surface area was relatively constant (23.9 ± 3.4 nmol cm-2 h-1), irrespective of seaweed surface area:volume (SA:V) ratio. Moreover, there was a linear relationship between rates of ammonium uptake per g dry weight and ammonium concentration for 2 of the species used, Xiphophora chondrophylla and Ulva sp., which had low and high SA:V ratios, respectively. These results are consistent with most or all of ammonium uptake being due to passive diffusion of NH3. In addition, of 3 other species investigated, Pterocladia capillacea, Porphyra sp. and Enteromorpha sp., only P. capillacea exhibited saturation kinetics. KEY WORDS: Seaweed · Nutrient uptake · Ammonium · Diffusion · New Zealand Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 169. Publication date: August 06, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.

Seismic refraction studies in the northern Hauraki Gulf, New Zealand

Abstract The seismic velocity structure of sediments and basement rocks underlying the continental shelf between Cape Rodney and the Moko Hinau Islands has been determined by seismic refraction measurements. A penetration of some 5 km was achieved along a 50 km reversed profile using 80 explosions on the sea floor. Jurassic greywacke rocks occur at shallow depths of 100–200 m beneath most of the central part of the profile. These basement rocks are downfaulted by about 2 km to the south-west in the south-western part of the profile; the 13-km-wide fault-angle depression between the coast and the major fault is infilled by a sequence of unconsolidated (?) Quaternary sediments and consolidated, older sediments. The unconsolidated sediments, which are characterised by a seismic velocity of 1.61 km/s, reach a thickness of more than 650 m in the eastern part of the depression and are underlain by a 500–800-m-thick layer of consolidated sediments with a mean velocity of 3.3km/s. The highstanding basement rocks in the central part are dissected by a graben 5 km wide and 250 m deep, infilled with unconsolidated sediments. The volcanic Pleistocene-Pliocene Moko Hinau Islands at the north-eastern end of the profile rest upon a 430-m-thick pedestal of volcanic rocks with a velocity of 3.1–4.0 km/s. The highstanding greywacke rocks in the central part have a rather high velocity of 5.0 km/s which increases to 5.95 km/s at 2.4 km depth. It is likely that the fault-angle depression and the graben are features belonging to the northern extension of the Hauraki Rift.

Juvenile slender tuna from New Zealand (note)

Abstract Two juvenile slender tuna Allothunnus fallai Serventy, 278 mm and 282 mm fork length, were identified from a catch by a purse seiner 23 km off the Moko Hinau Islands, New Zealand, on 23 January 1974. As the slender tuna were observed to school in association with skipjack tuna Katsuwonus pelamis L., it is probable that adults also school, and could be available as a yet unexploited resource to New Zealand fishermen, especially to the south‐east of New Zealand.