Wellington Harbour Research Articles

Reproductive biology of female big‐bellied seahorses

In this study, ovarian morphology, reproductive condition and sex steroid levels were investigated in the big‐bellied seahorse Hippocampus abdominalis, collected by snorkel and SCUBA diving in Wellington Harbour, New Zealand. Within the ovary, oocytes were contained between an outer muscular wall and an inner layer of luminal epithelium. Two germinal ridges ran along the entire length of the ovary. In cross‐section, oocytes were arranged in sequential order of development beginning at the germinal ridges and ending at the mature edge. Ovarian lamellae were absent. Vitellogenic and advanced cortical alveoli oocytes were elongated in shape, whereas maturing oocytes were distinctively pear‐shaped. Mature oocytes were large (2·6 – 4·4 mm in length) and aligned with the animal pole towards the muscular wall. Reproductively mature females were found throughout the year indicating a protracted reproductive season. The gonado‐somatic index was significantly different between all ovarian stages, but the hepato‐somatic index was not. Females with previtellogenic ovaries had significantly higher plasma concentrations of testosterone than females with vitellogenic or maturing ovaries. There was no significant difference in plasma concentrations of testosterone between females with vitellogenic or maturing ovaries, or in plasma concentrations of 17β‐oestradiol between females in all ovarian stages. This study contributes to the knowledge on the reproductive biology of female syngnathids.

Cyst and radionuclide evidence demonstrate historic Gymnodinium catenatum dinoflagellate populations in Manukau and Hokianga Harbours, New Zealand

Between May 2000 and February 2001, a major bloom of the toxic dinoflagellate Gymnodinium catenatum (a causative organism of Paralytic Shellfish Poisoning, PSP) affected over 1500 km of coastline of New Zealand’s North Island. As this was the first record of this species in New Zealand, we aimed to resolve whether this represented a recent introduction/spreading event or perhaps an indigenous cryptic species stimulated by environmental/climatic change. To answer this question, we analysed for G. catenatum resting cysts in 210Pb dated sediment cores (18–34 cm long; sedimentation rates 0.34–0.69 cm per year) collected by SCUBA divers from Manukau Harbour, where the species was first detected, and from Hokianga Harbour, where the highest shellfish toxicity was recorded, while using Wellington Harbour as a well-monitored control site. The results of this study conclusively demonstrate that abundant G. catenatum has been in northern New Zealand at least since the early 1980s, increasing up to 1200 cysts/g around the year 2000, but with low cyst concentrations possibly present since at least 1937. In contrast, Wellington Harbour cores contained only very sparse G. catenatum cysts (8 cysts/g), present only to a depth of 7 cm (surface mixed layer depth), reflecting an apparent recent range expansion of this dinoflagellate in New Zealand, possibly stimulated by unusual climatic conditions associated with the 2000 La Nina event. The significant increases since the early 1980s also of Protoperidinium cysts at Hokianga Harbour and of Gonyaulax, Protoperidinium and Protoceratium cysts at Manukau Harbour suggest a broad scale environmental change has occurred in Northland, New Zealand.

Natural diet of the seahorse Hippocampus abdominalis

This investigation examined the diet of adult wild seahorses, Hippocampus abdominalis Leeson 1827, from Wellington Harbour, New Zealand. Diet of seahorses (n = 59) collected from shallow subtidal macroalgal stands consisted largely of crustaceans, in particular amphipods (e.g., caprellid and ischyrocerid amphipods), caridean shrimp (i.e., Hippolyte bifidirostris), and peracarids (i.e., the mysid Tenagomysis similis). There were no differences in diet between male and female seahorses. Smaller seahorses consumed a greater amount of crustaceans than larger seahorses, as a result of the greater proportion of amphipods in their gut contents. There were some seasonal differences in diet, with amphipod consumption peaking in spring and summer, and decapod consumption lowest in autumn.

Revegetation and its Effect on the Ground‐Dwelling Beetle Fauna of Matiu‐Somes Island, New Zealand

AbstractA study of beetle (Coleoptera) communities was conducted in three revegetated sites of different ages (5, 17, and 100 years) and in a remnant coastal habitat dominated by Muehlenbeckia complexa (a liane) on Matiu‐Somes Island, Wellington Harbor, New Zealand. The 25‐ha island has had a 110‐year history as a pastoral agricultural quarantine station. Beetles were surveyed from May 1997 to April 1998 using pitfall traps. We collected a total of 3,430 adult beetles from 78 beetle species belonging to 22 families. Various environmental factors influencing the distribution of beetles in revegetated habitats were investigated. The most important factors were canopy height and canopy density (functions of vegetation age). Overall, results suggest that as habitat/vegetational heterogeneity increases at a site, beetle diversity and abundance also increase. Thus, older replanted sites contained a greater species richness and abundance of beetles than newly replanted sites. Revegetation is, thus, successfully facilitating the establishment and recolonization of the beetle fauna on Matiu‐Somes Island.

Occurrence and distribution of Karenia brevisulcata (Dinophyceae) during the 1998 summer toxic outbreaks on the central east coast of New Zealand

Massive mortality of marine life and algal blooms around central New Zealand during January and March 1998 have been attributed to the toxic dinoflagellate, Karenia brevisulcata (= Gymnodinium brevisulcatum). Phytoplankton surveys in January and February 1998 showed the presence of K. brevisulcata both offshore, in the relatively warm, southwards-directed East Auckland and East Cape Currents, and inshore, in the relatively cold, northwards-directed Wairarapa Coastal Current, along the entire east coast of the North Island. Small numbers of this species (200 cells 1−1) were also recorded on the southwest coast of North Island. A bloom of K. brevisulcata occurred in Wellington Harbour during February–March 1998. Reports of human respiratory distress progressed northwards along the Wairarapa Coast at about the same speed (0.23 m s−1) as observed for the Wairarapa Coastal Current, suggesting the passage of a bloom along the coast. We relate the timing of these events to local oceanographic conditions.

Biological effects of the toxic algal bloom of February and March 1998 on the benthos of Wellington Harbour, New Zealand

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 218:63-76 (2001) - doi:10.3354/meps218063 Biological effects of the toxic algal bloom of February and March 1998 on the benthos of Wellington Harbour, New Zealand Robert G. Wear*, Jonathan P. A. Gardner Island Bay Marine Laboratory, School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand *E-mail: bob.wear@vuw.ac.nz ABSTRACT: Wellington Harbour is a large (~85 km2), semi-enclosed temperate ecosystem. We used unpublished baseline data from 6 subtidal and 1 intertidal harbour stations to quantify the ecological effects of the naturally occurring toxic bloom of the naked dinoflagellate Karenia brevisulcata (Chang) G. Hansen & Moestrup during February and March 1998. Species richness decreased at 6 stations and increased at 1 station, numbers of individuals decreased at 4 of 4 stations, species diversity decreased at 5 of 5 stations, evenness decreased at 2 and increased at 2 stations, and biomass decreased at 2 of 3 stations. These data indicate that the K. brevisulcata bloom of late summer 1998 resulted in a mass die-off of the subtidal benthic invertebrates over a large area of Wellington Harbour, as well as of the flora and fauna at 1 intertidal location studied. Four major phyla (echinoderms, molluscs, polychaetes and crustaceans) were equally affected by the bloom, although different species within each phylum were differentially affected (regardless of phylum, small and shallow-burrowing individuals were most affected). Multivariate statistical analyses of these data identified 3 clusters composed of 4 subtidal stations which showed the highest level of impact by the bloom and were based on a spatial/environmental component (location in the northern harbour; greater depth; low current/wave energy) as well as a temporal component (pre- vs post-bloom). The remaining 3 subtidal stations were less affected by the bloom and each formed a separate cluster according to spatial/environmental rather than temporal effects. This event has permitted us to quantify, for the first time, the effects of a natural toxic bloom on a large-scale temperate harbour ecosystem and to relate the magnitude of these effects to the geographic and environmental properties of different locations within that ecosystem. KEY WORDS: Toxic algal bloom · Karenia brevisulcata (Chang) G. Hansen & Moestrup · Community die-off · Mass mortality · Community structure · Wellington Harbour · New Zealand Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 218. Online publication date: August 20, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Where are the mussels on Cook Strait (New Zealand) shores? Low seston quality as a possible factor limiting multi-species distributions

Examination of the physiological ecology of 3 sympatrically occurring mytilids (the ribbed, blue and greenshell mussels, Aulacomya maoriana, Mytilus galloprovincialis and Perna canaliculus, respectively) was carried out during summer and winter at 2 sites which differ markedly in their environmental characteristics (Mahanga Bay inside Wellington Harbour, where mussels are abundant, and Island Bay on the exposed Cook Strait shore, where mussels are absent). Seston components (particle counts per ml in the size range 2.5 to 63 μm, total particulate matter [TPM], particulate organic matter [POM], and percent organic matter [PCOM]) all varied significantly between sites and between seasons. Mahanga Bay seston exhibited characteristics typical of productive temperate coastal waters, whereas Island Bay seston was characterised by low POM and low PCOM values. Weight-standardised clearance rate (CR S ), net absorption efficiency (AE) and Scope for Growth (SFG) values were determined for all 3 mussel species at both sites during both seasons. At Island Bay there was no evidence of seasonal differences in CR S whereas at Mahanga Bay species-specific CR S values were all highest in the winter. Regardless of season, CR S estimates for all 3 species were higher at Mahanga Bay than at Island Bay. At both sites, AE estimates were highest in the winter, and AE estimates were higher at Mahanga Bay than at Island Bay during each season. SFG estimates mirrored AE estimates, with SFG at both sites being highest in winter, and higher at Mahanga Bay than at Island Bay during each season. The SFG data support the hypothesis that mussels are absent from sites along Cook Strait shores because they do not enjoy a positive energy balance for long periods of time, consistent with the low seston organic matter levels at such locations. The SFG data also indicate that mussels inside Wellington Harbour can maintain a large, positive net energy balance throughout the year, consistent with the considerable biomass and very large size of all 3 species in this environment.

Gymnodinium brevisulcatum sp. nov. (Gymnodiniales, Dinophyceae), a new species isolated from the 1998 summer toxic bloom in Wellington Harbour, New Zealand

Morphological characters of Gymnodinium brevisulcatum F.H. Chang sp. nov. are described from specimens collected during the 1998 summer toxic bloom in Wellington Harbour and cultures developed from the bloom. The new species, which dominated the early 1998 bloom, is very toxic and killed a large variety of micro- and macroalgae, invertebrates, and vertebrates in the harbor. Human respiratory distress was experienced from aerosols apparently originating from the bloom. Isolates of G. brevisulcatum were examined using both light and scanning electron microscopy. Gymnodinium brevisulcatum may be separated from G. mikimotoi Miyake et Kominami ex Oda (= G. nagasakiense) and other closely related species by several features: it has a very short apical groove on the ventral surface of the epicone; it is the smallest species within the Gymnodinium mikimotoi group; and the nucleus is either spherical and located in the left lobe of hypocone or at the division stage, it is horizontally elongated, extending left to right in the hypocone.

The effects of multiple trap spacing, baffles and brine volume on sediment trap collection efficiency

The hydrodynamic effects on trapping efficiency of sediment trap cross-frame position, baffles and brine volume were evaluated in three short-term (<I week) experiments in a temperate shallow marine environment (Evans Bay, Wellington Harbour, New Zealand). The effects of trap position and brine were further investigated during two open ocean, free-floating sediment trap deployments (1-2 days) near the Subtropical Front (STF), east of New Zealand. In the Evans Bay experiments (numbered I-III), cross-frames, each holding 12 cylindrical traps (inside diameter 9 cm, height 95 cm), were moored 3 meters above the seafloor in 15-18 m water depths at three randomly selected inner harbor sites. Triplicate subsamples from each cylinder were analyzed for total dry weight and mass fluxes calculated. The STF deployments utilized JGOFS MULTI-traps (inside diameter 7 cm, height 58 cm) attached to cross-frames moored at three depths (120, 300 and 550 m) on drifting arrays (Experiments IV and V). MULTI-trap samples were analyzed for total particulate mass, carbon and nitrogen. Results from Experiments I and V indicate that a spacing of about 3-trap diameters was sufficient to minimize inter-trap interactions and maintain trapping efficiency among traps suspended on a cross-frame at the same depth. Furthermore, baffles had no effect on trapping efficiency and an undetectable impact on zooplankton swimmer' populations also collected in traps (Experiment II). In Experiment III, traps that were filled completely with high-density salt brine (50‰ excess NaCl) collected 2-3 times less material than traps with a basal brine height equivalent to 1- and 2.5-trap diameters. In contrast, high levels of inter-site variability confounded the STF MULTI-trap deployments during Experiment IV. However, variability in flux measurements from both Experiments III and IV increased 2 to 3-fold in brine-filled traps. Thus, the potential for brine-filled traps to undercollect material with higher levels of variability could possibly explain previously reported inaccuracies in the sediment trap method.

New species of benthopelagic copepods of the genus Stephos (Calanoida: Stephidae) from Wellington Harbour, New Zealand

Two new species of benthopelagic calanoid Copepoda are decribed from Evans Bay, Wellington Harbour, New Zealand. The species Stephos hastatus n. sp. and S. angulatus n. sp. (Family: Stephidae) are the first records of this family and genus from New Zealand.

Acid leached analyses of stormdrain and harbor sediments, New Zealand

Sediments from stormdrain catchments in Wellington city and sediment traps from Wellington Harbor were sampled for trace metal content. Samples were analyzed for acid leached metal content by extraction with 0.11 mol acetic acid l–1 and using ICP-MS. Cu and Zn levels in harbor sediment traps increased towards the periphery of the harbor, while Pb levels adjacent to a road almost doubled. In general, areas of light industry in the Inner City stormdrain catchments exhibited higher acid leached metal concentrations. However, large-scale renovation work probably contributed to point sources of high metal levels. The proximity of stormdrain outlets to recreational activities, such as wharf fishing and shellfish gathering, should be of prime concern to local authorities.

A contemporary contamination record of stormdrain and harbour sediments, Wellington, New Zealand

Sediments from stormdrain catchments and outlets in Wellington city and sediment traps from Wellington Harbour were sampled for trace metal content. Samples were analysed for total metal content using XRF and ICP-MS. High values of Pb and Zn were found in stormdrain catchments and outlets, decreasing to elevated background rock levels in the harbour. Maximum values were recorded in an inner city stormdrain catchment, with levels of Pb (4605 ppm), Cu (2981 ppm) and Zn (3572 ppm) all higher than the biological probable effects levels (PEL). Concentrations of As, Cr, Cu, Pb, Ni and Zn concentrations in all harbour sediment trap samples were below the PEL. The mean values for each harbour sediment trap sample can be used as an accurate historical baseline in future studies. Stormdrain samples with high trace metal levels were close to industrial and construction sites. The proximity of these outlets to recreational areas should be of concern to local authorities.

Size-dependent, spatial and temporal genetic variation at a leucine aminopeptidase (LAP) locus among blue mussel ( Mytilus galloprovincialis ) populations along a salinity gradient

Biochemical genetic variation at a leucine aminopeptidase (LAP) locus is related to salinity variation in several marine bivalve molluscs. This paper details an investigation of the Long Island Sound model of LAP selection (LAP genotype-dependent mortality occurring among newly settled Mytilus edulis mussels) carried out in 1997 among three M. galloprovincialis mussel populations along the salinity gradient of Wellington Harbour, New Zealand. Significant LAP genotypic heterogeneity was observed at the LAP locus between small ( 25 mm shell length) M. galloprovincialis from Petone and Eastbourne (the two sites experiencing the greatest salinity variation), whereas genotypic heterogeneity was not significantly different between small and large mussels from Seatoun (the site experiencing the least salinity variation). The Lap3 allele decreased in frequency and the Lap4 allele increased in frequency at Petone and Eastbourne, whereas the Lap3 and Lap4 allele frequencies remained effectively constant at Seatoun. Both these findings are consistent with the Long Island Sound model of selection. At all three locations, the Lap3,3 genotype decreased in frequency from small to large mussels, whereas the Lap3,4 genotype increased in frequency from small to large mussels. All other LAP genotypes occurred at low frequencies (<0.10) at all three locations and showed no evidence of frequency change from small to large-size mussels nor evidence of clinal change among the three locations. These genotype frequency data possibly indicate that the Lap3,3 genotype is at a selective disadvantage compared to the Lap3,4 genotype at all three locations, and that this selective disadvantage is related to the extent of salinity variation which exists at each location. Further investigation is required before it can be determined if the Long Island Sound model of selection best describes the size-dependent and location-specific changes in LAP allele and genotype frequencies along this salinity gradient. Comparison of the population genetic structure at the LAP locus in 1995 and in 1997 revealed a profound change from heterozygote excesses to heterozygote deficiencies for all three M. galloprovincialis populations. The reason for the change is unknown, but the change indicates that population genetic structure at the LAP locus is highly variable in time, but consistent in space, among these M.␣galloprovincialis populations.

Tests for Mate and Nest Fidelity in Birds with Application to Little Blue Penguins (Eudyptula minor)

In a study of little blue penguins (Eudyptula minor) in Wellington Harbour, we wished to test for mate and nest site fidelity. Previous penguin work had only given descriptive statistics such as percentages. Given that each little blue penguin returns to a very small area for breeding, its choice of mate and nest site is extremely limited. A test of randomness of mating and nest site selection was therefore required in the context of this very restricted choice. This paper provides such a test for randomness versus mate or nest site fidelity, based on the rencontre probability problem. It combines information from several sites and requires data over at least two successive seasons. For this study, the test was powerful enough to detect nonrandomness of mate and nest site selection with a very small amount of data.

Holocene pollen stratigraphy and sedimentation, Wellington Harbour, New Zealand

Pollen and spore spectra obtained from within, and around, Wellington Harbour provide a record of climate and land‐use change from early Holocene to the present day. Samples of four cores from Wellington Harbour show that Nothofagus group pollen has increased six‐fold relative to Dacrydium cupressinum since c. 10 000 years ago. From A.D. 1840 there is evidence of land clearance and the introduction of exotic species by European settlers. Historical records show that 80–90?% of the native forest was replaced with grassland between A.D. 1840 and 1900, a far greater land‐use change than that indicated by the pollen record. Palynomorphs from the modern harbour floor contain assemblages similar to those obtained from contemporary forested terrestrial sites. Both are dominated by Nothofagus group, Dacrydium cupressinum pollen, and fern spores. In contrast, assemblages from non‐forested areas are dominated by the local pollen source and contain considerable grass and shrub spores. There is a uniform, mixed nature to the palynomorph spectra in Wellington Harbour. It is concluded that almost all pollen entering Wellington Harbour does so via the Hutt River from reworked forested parts of the upper river catchment.

Biochemical genetic variation at a leucine aminopeptidase (LAP) locus in blue ( Mytilus galloprovincialis ) and greenshell ( Perna canaliculus ) mussel populations along a salinity gradient

In several marine bivalve species, biochemical genetic variation at a leucine aminopeptidase (LAP) locus is associated with environmental variability, primarily salinity fluctuation. Population genetic variation at a LAP locus was investigated here in two sympatric mussel species (Mytilus galloprovincialis and Perna canaliculus) from three locations along a salinity gradient in Wellington Harbour, New Zealand. The data for M. galloprovincialis and P. canaliculus do not support the hypothesis that the LAP polymorphism in either species is associated with salinity variation among adult mussels. Due to the absence of small mussels among the samples it is not possible to discount the hypothesis that selection acts primarily against juveniles, as it does for M. edulis in Long Island Sound, USA. Wellington Harbour populations of M. galloprovincialis exhibited large and often highly significant heterozygote excesses at the LAP locus, whereas populations of P. canaliculus from the same locations exhibited large and highly significant heterozygote deficiencies. The reason for this inter-specific difference in population structure is unknown. If it is the result of selection, this suggests that selection acts differentially upon the two species, because demographic attributes and reproductive biology are very similar in the two species. For both M. galloprovincialis and P. canaliculus, significant levels of population genetic heterogeneity were recorded among three locations separated by only 8 to 12 km. Neither species exhibited shell length-dependent genetic variation at the LAP locus, suggesting that for these two species the LAP polymorphism is not associated with variation in shell length.

Estimating vertical tectonic movement using sediment texture

We demonstrate a new method of detecting, and quantifying, vertical sea-floor movements caused by tectonic uplift from a large earthquake, based on grain-size data from two cores from Petone foreshore, Wellington Harbour, New Zealand. An earthquake of magnitude 8+ raised the shores of Wellington Harbour about 2 m in AD 1855, according to historical records. This event has been recognized in two nearshore cores as a sharp decrease in mud content of 15-20% at 3.75 and 4.25 m below the sea floor (bsf). The decrease is attributed to decreased water depth resulting in higher nearshore wave-induced energy levels. The two levels in the core have been dated approximately by 14C, palynology and variations in heavy metal concentrations and are consistent with a date of AD 1855 for the abrupt shallowing of the foreshore. We infer that the mud-depth relationship has probably been affected since European colonization (post-AD 1840) by increased sediment input into the harbour. Chronological markers in the two cores suggest that rates of sediment accumulation have increased by a factor of at least ten, from ∼2 mm yr-1 prior to AD 1855 to 30 mm yr-1 since then.

Seiche modes of Wellington Harbour, New Zealand

Seiche currents were observed in Wellington Harbour, New Zealand, with an Acoustic Doppler Current Profiler (ADCP). A 600 kHz Broad‐Band ADCP was deployed on the sea bed in Evans Bay in an upwards looking configuration for 20 days. The measured seiche periods were 159, 26, 17.3, and 8.3 min and there was evidence for seiching at periods of 15.8 and 14.7 min. These observations are in close agreement with the previous predictions of a finite‐difference numerical model. The seiching occurred during periods of wind with speeds in excess of 10 m s−1 The seiches were found to be barotropic.

A chronology of natural and anthropogenic influences on coastal sedimentation, New Zealand

14C and 137Cs chronologies of sediment accumulation were obtained from five sediment cores taken from Wellington Harbour, New Zealand. A 10,000-year chronology records the Holocene transgression, European colonisation, and variations in the general sediment accumulation rate caused by earthquake uplift and anthropogenic activity. Rates vary from a high of ~ 60 to a low of 0.1 mm a−1. In general, rates increased at the beginning of the Holocene marine transgression, but by ~ 5000 yr BP they reached a stable level. Harbour-wide, these rates remained stable until the second half of the 19th Century when deforestation by European settlers caused order of magnitude increases in sediment accumulation. In the past 40–80 years rates have increased again as a result of urban growth and river channel management, although the effects are less pervasive. Harbour-wide influences can be placed in two categories, natural and anthropogenic, the latter being recent contributions to a sedimentary regime dominated by the Holocene marine transgression.Sediment accumulation rates indicate that two major earthquake uplift events had only a local effect on harbour sediments. Anthropogenic influences are considered to be more significant sedimentologically than earthquake activity.

Records of adventive marine algae in New Zealand:Antithamnionella ternifolia, Polysiphonia senticulosa(Ceramiales, Rhodophyta), andStriaria attenuata(Dictyosiphonales, Phaeophyta)

Abstract Three species of introduced marine macroalgae are reported for Wellington Harbour (North Island, New Zealand). One of these, Polysiphonia senticulosa (Ceramiales, Rhodophyta) is illustrated from New Zealand for the first time, and the known distributional ranges of two species, Striaria attenuata (Dictyosiphonales, Phaeophyta) and Antithamnionella ternifolia (Ceramiales, Rhodophyta), are extended to the North Island.