Distributions and associations of benthic invertebrates in a sheltered water soft‐bottom environment (Marlborough sounds,New Zealand)

Distribution patterns of benthic invertebrates in the Marlborough Sounds are related to depth and sediment grade. The assemblage of species found living in this sheltered water soft‐bottom area is characterised by two species of polychaete of the genus Asychis, Echinocardium cordatum, and Amphiura rosea The relationship of this association in the Marlborough Sounds to similar associations in other areas is briefly discussed.     

Do predatory fish of benthic crustaceans vary between kelp and barren reef habitats in northeastern New Zealand?

Fish assemblages that included known predators of benthic crustaceans were compared between kelp and barren habitats in northeastern New Zealand using baited underwater video census methods. The benthic-feeding fish were observed in winter, spring/summer and autumn, as well as during night-time in spring/summer. Overall, the fish assemblages varied between barren and kelp habitat, being most marked in winter. Individual benthic-feeding species, such as grey mao mao (Scorpis lineolatus) and leatherjacket (Meuschenia scaber) were associated with barren habitat, while the spotted wrasse (Notolabrus celidotus) was more strongly associated with kelp habitat. The results suggest that changes in habitats on coastal reefs affect populations of species that are benthic predators, which may in turn influence the distribution and abundance of their prey species, such as juvenile spiny lobsters.     

Relationship between long‐term changes in algal community structure and herbivore diet at the Three Kings Islands,New Zealand

We examined temporal changes at the Three Kings Islands, New Zealand in 1993 and 2002 in the diet of the endemic herbivorous fish Odax cyanoallix (Family Labridae) and in habitat‐forming macroalgae, and compared these with published accounts from 1979. The diet of O. cyanoallix predominantly comprised the laminarian Ecklonia radiata in 1993, and the fucoids Sargassum johnsonii and Landsburgia quercifolia in 2002. In depths <10 m, the endemic fucoid S. johnsonii was dominant in 1979 and 2002 and absent in 1993. E. radiata was absent in 1979, abundant in 1993, and rare in 2002. A period of significantly lower sea‐surface temperatures (SST) at the Three Kings Islands in 1990–95 corresponded to an unusually long El Niño event. The low SST may have resulted in the failure of S. johnsonii to grow and/or recruit during the El Niño event, leading to the observed changes. This study demonstrates variability in fucoid and laminarian assemblages over large time scales that are reflected in diet shifts in a species of herbivorous fish.     

Albacore off the north‐west coast of New Zealand,February 1972

During two trolling surveys in February 1972, albacore, Thunnus alalunga (Bonnaterre), were located between Cape Reinga and Cape Egmont, but were more abundant between Kaipara Harbour and Albatross Point. Fish catches and associated hydrological data are presented. Albacore were caught only in areas where the sea surface temperatures were between 18.5°c and 21.3°c, and usually in areas where the water was blue and the bottom depth between 45 m and 80 m. The albacore were mainly of the 2‐ and 3‐year age‐groups. Of the 665 fish landed, 449 were tagged and released, but no recoveries have been made.

Commercial vessels located albacore within 20 km of New Plymouth during the summers of 1970 and 1971 when sea surface temperatures were 1.5–2.5°c higher than in February 1972, probably because of a more southward extension of the West Auckland Current in 1970 and 1971.     

Land use effects on habitat,water quality,periphyton, and benthic invertebrates in Waikato,New Zealand,hill‐country streams

Water quality, habitat, and biota were compared during spring amongst c. 100 m reaches on 11 streams draining pasture, native (podocarp‐broadleaf) forest, and exotic pine forest established on pasture 15 years previously. Differences were greatest between the pasture and native forest streams. Only 1–3% of incident light reached native and pine forest streams whereas 30% reached pasture streams. Pasture streams had 2.2°C higher mean temperature than the native streams, and 5‐fold higher nitrate, 30‐fold higher algal biomass, and 11‐fold higher gross photosynthesis. Native streams were 60% wider than pasture, with pine streams intermediate. Pine and pasture streams had 3‐fold higher suspended solids and fine sediment stored in the streambed than native streams. Woody debris volume was 17‐fold greater in pine than pasture streams, with native streams intermediate. Invertebrate taxa richness did not differ between land uses. Community composition differed most between pasture and native forest, with pine forest streams intermediate. Invertebrate densities were 3‐fold higher in pasture than native streams, mainly because of more chironomids and snails, but mayflies, stoneflies, and caddisflies densities were 2–3‐fold higher in forest streams than pasture.     

How to detect polymorphisms undergoing selection in marine fishes? A review of methods and case studies,including flatfishes

Populations of marine organisms are potentially affected by numerous selective pressures such as temperature and salinity, or anthropogenic pressures such as xenobiotics that may preclude adaptation to particular habitats. Such selective pressures may also affect their demography. Examples include modifications of the population dynamics through shifts in growth rate, and in life history traits affecting fitness such as size or age of first reproduction. However, the documentation of variation in phenotypically plastic traits specific to distinct environments cannot be taken as the ultimate proof that natural selection has occurred. Measurement of the impact of selection and subsequent local adaptation of fish populations based exclusively on morphological or physiological characters is one of the most difficult things to achieve because it depends on the use of phenotypic characters that closely match the genotype. Molecular markers can help to overcome this problem and, under some circumstances, can record the footprints of selection. A combination of polymorphisms that are under selection and those that are not can provide complementary information. In this paper, we review how and why selection can be detected at the molecular level, using genetic markers analysed in a population genetic framework. We then report and discuss case studies in fish.     

Distribution and abundance of demersal fish from trawl stations in the bay of plenty,New Zealand, 1961–63

Between March 1961 and January 1963 trawling surveys were carried out in the Bay of Plenty. Seasonal comparisons of catch weight were made for the four commercially important species, snapper, tarakihi, trevally, and gurnard, during 1962–63. Only trevally showed any marked seasonal variation in total catch. Tarakihi were most abundant in waters over 50 fathoms and snapper, trevally, and gurnard were most abundant in shallower depths. The best return for fishing effort came from the middle sector of the Bay. There was a marked absence of undersized tarakihi and trevally from the catches. A species composition list for the Bay of Plenty waters and a table of species abundance at the stations sampled has been compiled from the trawl catch data.     

Trawl fisheries,catch shares and the protection of benthic marine ecosystems: Has ownership generated incentives for seafloor stewardship?

Proponents of catch share-based fisheries have claimed ecological stewardship can result from the assignment of individual catch quotas. This claim is examined by analyzing the distribution of benthic habitat protection measures adopted by quota-owning industry sectors within the exclusive economic zones (EEZs) of the U.S. (Alaska), New Zealand, and high seas seamounts within the Southern Indian Ocean Deepsea Fishers Association (SIODFA) competence area. Results suggest the protection of both benthic ecosystems and essential fish habitat (EFH) are marginal at best when quota owners have primacy in determining the boundaries of bottom trawl closures. The majority of the areas in these three regions that are closed to trawling are too deep to fish, may not contain vulnerable marine ecosystems, and do not have high abundances of commercially important species. “Freezing the footprint” of bottom trawling is not the best method for benthic habitat protection in areas where the fishing industry is actively fishing vulnerable habitats. Analytical methods should be applied to help determine boundaries of future bottom trawl closures rather than allowing the fishing industry to place benthic protection areas (BPAs) in areas where they are not interested in fishing.     

Seasonal hydrology of waters off the Otago peninsula,South‐Eastern New Zealand

Variations of temperature and salinity were observed off the Otago Peninsula from October 1966 to December 1967. In‐shore temperatures were more variable than those seawards and variability decreased with increasing depth. Temperatures over the continental shelf and down to 200 m in the open sea varied seasonally. Below 200 m temperature variations were small and non‐seasonal. Salinities were depressed in the shallow coastal waters by land run‐off, this tendency being more pronounced in autumn and winter. Seawards of this coastal zone seasonal variations of salinity were small. Over the outer shelf a zone of higher salinities was always present. Beyond this zone salinities decreased with increasing distance from shore and with increasing depth. A salinity minimum was sometimes present between 500 and 1,000 m.

Although the upper 200 m were seasonally stratified, the same water masses could always be recognised. Two water masses were present near the surface, the Southland Current, here interpreted as being subtropical in origin, being located in shore of Subantarctic Surface Water. These two water masses are separated by the clearly defined Southland Front. Along the shore, neritic conditions develop through modification of Southland Current water by coastal and climatic effects. Seawards, beneath Subantarctic Surface Water, the core of Antarctic Intermediate Water could sometimes be recognised as a salinity minimum.     

A study of the chemical composition and transport of marine aerosols over the ocean near China

In this paper the authors cite the aerosol samples collected with a KA-200 Anderson cascade Impactor and a KB-120 sampler during the first cruise of the Kuroshio investigation operated by the People's Republic of China and Japan cooperative program, from July 23 to August 21, 1987. The concentration size distributions and composition of marine aerosols over the Kuroshio area are analyzed. Neutron activation analysis is used to determine the elemental composition of the aerosols. The authors also discuss some characteristics of marine aerosols relating to long-range transport of crustal and anthropogenic elements from the continent to the remote ocean. Analytical results indicate that elements Al, Fe, Sc and Sb over this area are obviously influenced by the continent of Asia, and the size distributions are changed after long-range transport. The concentration of large particles increase. The concentrations of the elements C1 and Na are closely related to ocean conditions; the source of the elements Cl an     

Land‐use impacts and water quality targets in the intensive dairying catchment of the Toenepi Stream,New Zealand

Water quality monitoring in Toenepi Stream, New Zealand, started in 1995 in a study of dairy farming influences on lowland stream quality and has continued since then with brief interruptions. Surveys have provided information about changes in farm and soil management practices as they relate to environmental sustainability. Although average water quality in Toenepi Stream has changed little during 1995–2004, there have been some notable improvements. Water clarity measured by black disc has improved from 0.6m to 1.5m, and median ammonia‐N and nitrate‐N concentrations have declined by 70% and 57%, respectively. The frequency and magnitude of extreme concentrations have declined—most notably for nitrogen (N) forms, which also had decreased mean values. Specific yields for suspended solids (SS) and phosphorus (P) forms in 2002–04 were 47–67% of 1995–97 values, mainly because of lower water yields. Reduced specific yields for N forms in 2002–04 (34–37% of 1995–97 yields) were also attributable to lower mean concentrations in stream water. Faecal bacteria concentrations have not abated and are on average 2–3 times recommended guideline values for contact recreation. Fewer dairy farms and an increased proportion irrigating dairyshed effluent to land, rather than discharging it to the stream via two‐pond systems, were likely causes of improvement in water quality. Water quality targets were developed for Toenepi Stream to achieve contact recreation criteria for the Piako River (downstream) and for intrinsic habitat values for Toenepi Stream. A range of mitigation measures has been formulated to meet these targets, but substantial uptake of sustainable farming practices is needed to improve water quality in Toenepi Stream.     

Nature and quantity of net‐seston exported from Lake Taupo to the Waikato River,New Zealand

Over a diel cycle, the concentration in Waikato River water of negatively buoyant seston and of some animals from the littoral of Lake Taupo was significantly correlated with the velocity of wind over the lake. Riverine abundance of several littoral, lacustrine animals was significantly correlated with the weight of negatively buoyant seston. A significant negative correlation existed between the densities of negatively buoyant and positively buoyant seston in the river. In qualitative comparisons, eulimnetic species were sometimes over‐represented and sometimes under‐represented in river water, with no consistent pattern. Concentrations of eulimnetic species in river water were usually greatly less (down to 10^‐2) than those in the lake. The range of densities of zooplankters (> 160 μm in size) in the river was c. 20–2000 ind. m^‐3. Significant differences in the density of eulimnetic species in the river occurred at different times of the day, but on only 1 occasion was this probably linked to diel vertical migration in the lake. An increased rate of discharge from the lake may cause an increase in the density of some taxa in the river. The mean daily export of Botryococcus from the lake was at least 230 kg dry weight Forty‐five animal taxa derived from the littoral region of the lake were collected from the river including many not hitherto recorded from Lake Taupo.     

A note on the fauna of a ripple‐marked sandy sediment in western cook strait,New Zealand

Photographs of a ripple‐marked sea bed are reproduced together with the results of a mechanical analysis of the sediment and a list of the animals found. The sparseness of the fauna is attributed to the mobility of the substrate.     

Structure of a mudflat diatom community in the Avon‐Heathcote Estuary,New Zealand

Parameters of community structure (species composition and relative abundance, number of taxa, diversity, evenness, and cell density) were measured for a mudflat diatom community in the Avon‐Heathcote estuary, New Zealand. Fifty three diatom species were identified: 25 taxa (species and varieties) are new New Zealand records. The Shannon‐Wiener information index (H') was 3.46, indicating high diversity. Evenness (J') ranged from 0.57–0.67. The association between the biomass of the pulmonate gastropod, Amphibola crenata, and benthic diatom community structure was studied using large open enclosures (4.0 m²) to manipulate snail biomass. Community structure was compared at 0, 5 (natural biomass), and 10 g A. crenata dry weight per m. A similarity index (SIMI=0.88–0.95), as well as H’ and J’ indicated close similarity between the diatom assemblages within all enclosures, but number of taxa increased from 33 to 49 with increasing snail biomass. Cell densities were significantly lower at high snail biomass (6088 valves per mm²) compared to enclosures with no snails (10 110 valves per mm ). A. crenata had a higher ratio of diatom fragments to whole diatom valves in its faeces (2.42) than in its crop (0.55), indicating that it is capable of fragmenting diatoms.     

Postal surveys of anglers fishing for sea‐run Chinook salmon on the Rakaia River,Canterbury, New Zealand, 1973/74 and 1974/75.

Postal probability surveys were used to estimate the angler catch of salmon, and the number of anglers fishing for salmon, on the Rakaia River, Canterbury, New Zealand, for the seasons 1973/74 and 1974/75. Response levels of over 97% were obtained. An estimated 3531 fish were caught by an estimated 4405 anglers in 1973/74 and 4875 fish by 5332 anglers in 1974/75. The sample catch frequency distributions returned were highly positively skewed with few anglers catching most of the fish. The effect of this skewness on the estimate of total catch was investigated by bootstrapping and confidence intervals thus set were compared to those derived from the Gaussian assumption. Confidence limits were obtained for the estimate of number of anglers.     

A study on benthic community structure in west of the Taiwan Strait and near the Taiwan Shoals

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Physical characterisation and a biologically focused classification of “seamounts” in the New Zealand region

The physical, biological, and oceano‐graphic characteristics of seamounts of the New Zealand region of the South Pacific Ocean are poorly known. The aim of this study was to present a synopsis of the physical characteristics of seamounts within the region, and to present a preliminary classification using biologically meaningful variables. Data for up to 16 environmental variables were collated and used to describe the distribution and characteristics of the c. 800 known seamounts in the New Zealand region. Seamounts span a wide range of sizes, depths, elevation, geological associations and origins, and occur over the latitudinal range of the region, lying in different water masses of varying productivity, and both near shore and off shore. As such, it was difficult to generally describe New Zealand seamounts, as there is no “typical” feature. Thirteen environmental variables were included in a multivariate cluster analysis to identify 12 seamount similarity groupings, for a subset of over half the known seamounts. The groupings generally displayed an appreciable geographic distribution throughout the region, and were largely characterised by a combination of four variables (depth at peak, depth at base, elevation, and distance from continental shelf). In the future, the findings of the present study can be tested to determine the validity and usefulness of the approach for directing future biodiversity research and informing management of seamount habitat.     

Velocity measurements in the East Auckland Current north‐east of North Cape,New Zealand

Flow in the East Auckland Current (EAUC) system to the north‐east of North Cape, New Zealand is examined using data from two current meter mooring arrays, with supporting data from conductivity/temperature/depth (CTD) and satellite altimetry. Variable currents up to 45 cm s_–1 were observed. The variability was partly attributable to changes in position and strength of the North Cape Eddy whose centre lies some 150 km offshore. The observed flows across the mooring line correlate well with those estimated from satellite altimetry. This gives confidence in the use of the satellite data to estimate the transport variability in the EAUC in the 1992–2001 period. No seasonal cycle was found in the volume transports but rather broadband variability at periods longer than 100 days.