摘要:

Under hypoxic environmental conditions, slowly burrowing bivalves such as the pipi (Paphies australis) and cockle (Austrovenus stutchburyi) support anaerobic energy production through the pyruvate reductase enzymes strombine dehydro‐genase and alanopine dehydrogenase. Rapidly digging surf clams such as the tuatua (P. sub‐triangulatum) and trough shell (Mactra discors) do not fare as well at low oxygen levels, but perform better under the functional anaerobiosis generated by burrowing, and energy production is supported by octopine dehydrogenase. Muscle buffering capacity is higher in rapidly burrowing species and is correlated with total pyruvate reductase activity. Anaerobic pathways inP. subtriangulatumled to both D‐lactate and octopine accumulation during environmental hypoxia, but only octopine accumulated during burrowing. Bivalves adapted to environmental hypoxia maintained high adenylate energy charge (AEC) under anaerobiosis, indicating a close matching of ATP production to consumption. AEC fell inP. subtriangulatumduring environmental hypoxia. The significance of these findings is discussed within an ecological context, and in relation to the storage of live clams for the seafood industry.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516649

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The assimilation of nitrate (NO−3), ammonium (NH+4), and urea by size‐fractionated natural assemblages of phytoplankton, as a function of the individual ambient nitrogen (N) nutrient concentrations, was investigated off the west coast of South Island, New Zealand, in February 1989. New production (ρ NO−3) contributed by all three size classes was higher inshore than offshore, and accounted for 40–61% and 19–29% of the total N production (ZpN), respectively. The reverse was true for regenerated production [ρ NH+4+ ρurea], a clear indication of the importance of NH+4and urea in offshore waters. Picoplankton (< 2 μm fraction), both inshore and offshore, was the major user of the regenerated N, and accounted for 43–62% of total regenerated production. The assimilation rates of all three size components achieved saturation at the larger additions of NO−3, NH+4, and urea, and the half‐saturation constants (Ks) of all three N nutrients for the three size classes in summer were higher than the respective ambient N concentrations. Low ambient dissolved nitrogenous nutrients (DNN), low dissolved reactive phosphate (DRP), and low Vamb/Vmaxratios recorded in summer off Westland imply that the natural assemblages of phytoplankton, especially the larger components in inshore waters, were under nutrient stress.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516650

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Measurements of otolith and head dimensions of the ling,Genypterus blacodes, were used to test for morphometric variation in this species in the sea around New Zealand. Canonical discriminant analysis and multivariate analysis of variance showed that ling from the west coast of the South Island and from the Chatham Rise and Canterbury waters generally had longer and narrower heads and thinner otoliths than ling from the southern areas. There was evidence for at least three separate ling stocks in the New Zealand Exclusive Economic Zone.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516651

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Hoki (Macruronus novaezelandiae) have been commercially exploited in New Zealand waters since the early 1970s. During the 1980s there was a considerable expansion of the fishery which in turn created a need for better information on the size of hoki stocks. The fishery is based on large spawning aggregations which form off the west coast of South Island during winter. The size of this spawning stock has been estimated using hydroacoustic techniques. The acoustic equipment and the survey design have evolved during the period 1985–91. Several practical and theoretical problems were overcome: those of acoustically surveying deepwater fish during winter, and achieving an adequate signal‐to‐noise ratio; and the development of a method for estimating the biomass of a transient fish population. The relative spawning biomass indices derived from west coast South Island surveys are now central to the assessment of the western hoki stock.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516652

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The prevalence and abundance of nine species of ectoparasites and seven species of endoparasites found on the snapper,Pagrus auratus, collected from the Hauraki Gulf, New Zealand, is reported. The metazoan fauna ofPagrus auratusin this study was dominated by a single highly prevalent and abundant species,Diphthero‐stomumsp., which accounted for 84% of all the parasites collected during this study and occurred in all snapper older than 2 years. Several other moderately abundant species were highly prevalent, occurring in 50–60% of the snapper sampled. These includedLamellodiscus pagrosomi, Bivagina pagrosomi, Cucullanussp., andUnicolax chryso‐phryenus. The remainder of the parasite fauna comprised rare species of limited prevalence and low abundance, accounting for 7.7% of the individuals collected. These includedChoricotyle australiensis, phyllobothriid and dasyrhynchid plerocercoids,Proctoecessp.,Philometra lateo‐labracis, andAnisakissp. Correspondence analysis indicated that different age classes of the host snapper had distinctive parasitic faunas, with 0+ snapper characterised by low abundance and prevalence of all species exceptC. australiensisand the phyllobothriid plerocercoid. A progressive increase in many of the species of parasites constituted the major faunistic differences between 1+, 2+, and 3+ snapper. The implications for fisheries and aquaculture of the composition of the metazoan parasitic fauna ofP. auratusare discussed.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516653

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The metazoan parasites of the snapper,Pagrus auratus, collected in the Hauraki Gulf of New Zealand were surveyed and their distribution mapped and examined in relation to the age of the host. Nine species of ectoparasites and seven species of endoparasites were recorded and all were found to exhibit some degree of site‐specificity. The gill monogeneansLamellodiscus pagrosomiandBivagina pagrosomiwere found in well‐defined microhabitats on the gills.L. pagrosomiwas abundant on the middle section of the second gill arch and was found in greater numbers on the distal zone of the gill filaments of the external hemibranch. In contrast,B. pagrosomiwas particularly abundant on the first gill arch and on the basal zone of gill filaments of the external hemibranch. A third gill monogenean,Choricotyle australiensis, was found attached to the gill filaments in snapper of 3 years and older but was largely restricted to the buccal cavity in younger host fish. This suggests that site‐specificity may not be a static attribute but may alter along with other parameters of the host fish such as age and size. The gastro‐intestinal parasites were also found to exhibit habitat partitioning and segregation into specific niches with a highly site‐specific digenean,Diphtherostomumsp., occurring almost exclusively in the lumen of the rectum.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516654

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Sea level variability in the weather band (periods 5–20 days) was examined using 19‐month records at two sites off the west coast of New Zealand. These records were considerably longer than those previously available, allowing investigation of the seasonal changes in wind‐forced coastal‐trapped wave activity. The records show no seasonal changes in long‐wave activity and no propagation of energy from the North Island to the South Island shelf. Dynamical modelling of the New Plymouth record re‐affirmed that most of the variability arose through the alongshore wind stress. In contrast, empirical modelling of the Abut Head (South Island) record required the inclusion of long‐wave generation in the Taranaki Bight/Cook Strait region as well as the alongshore wind stress. The largest event in both records was associated with tropical cyclone Bola, but had different characteristics at each site.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516655

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The population size, distribution, breeding, and onshore habitats of New Zealand fur seals in the Nelson‐northern Marlborough region, New Zealand, were investigated. Breeding occurs at four relatively new rookeries along the southern shores of Cook Strait: at Stephens Island in the outer Marlborough Sounds, at Archway Islands and Pillar Point near Cape Farewell, and at Tonga Island in Tasman Bay. These rookeries were established in about 1970, 1980, 1988, and 1988, respectively. In 1993–94 about 500 pups were born and the extant population breeding or born at the four rookeries was assessed as 2410. There were also 17 hauling grounds, each with 25 or more seals ashore in winter, and about 50 other sites where lesser numbers hauled out regularly. Comparison with earlier estimates indicates that the summer population increased from about 70 in 1973 to about 1000 in 1994—a sevenfold increase of yearling and older seals. The number of pups produced increased at a mean annual rate of 23% since 1970–71. The population in this region is expanding rapidly in both numbers and breeding range, and similar trends have been reported from elsewhere in New Zealand and Australia. These changes relate to a re‐colonisation of traditional breeding grounds following cessation late last century of nearly 1000 years of human exploitation of New Zealand fur seals.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516656

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effluent characteristics of 11 domestic sewage waste stabilisation lagoons designed to national specifications were examined, with emphasis on their optical properties, biochemically active constituents, and receiving water impacts. Measurements of 26 variables were analysed and compared with our previous (1989) survey of lagoon effluent quality in New Zealand. There was considerable variation in effluent composition of the lagoons, although seasonality was not marked (< 3‐fold change between summer and winter). The filterable proportion of total BOD5 appeared to be a useful indicator of lagoon performance. Nutrient levels in lagoon waters were high (overall medians were 5.1 g m−3for dissolved reactive phosphorus and 10.5 g m−3for dissolved inorganic nitrogen). The concentration of ammoniacal‐N, which comprised most of the dissolved inorganic nitrogen, was highly variable (ratio of 95 to 5 percentile = 1900); this is of concern as a toxicant both to algae within lagoons and to aquatic life in receiving streams. Aquatic humus and algal biomass both contribute to the restricted light penetration (median euphotic depth‐0.35 m) into lagoon waters (typically 1.2 m depth), apparently resulting in frequent light limitation of algal photosynthesis. Pond effluent character seems to be influenced strongly by sunlight and wind, via their effects on lagoon solids (largely algal biomass and associated detritus). Dilution of lagoon effluents by 40‐fold would ensure that receiving streams meet existing guidelines for most attributes of concern, but > 100‐fold dilution may be required to prevent visual clarity impacts, and several hundred‐fold dilution to prevent benthic algal proliferations.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516657

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We have madein situobservations of the optical properties of Waikoropupu ("Pupu") Springs, Nelson, New Zealand. Visual clarity was measured in the horizontal direction over a sight path “folded” using a plane mirror so as to accommodate the sighting range within the 35 m wide main springs basin. An average black‐body visibility of 63 m was obtained, the highest yet reported for any fresh water, and close to the theoretical maximum for optically pure water. Measurements with a beam transmissometer were consistent with the visibility observations. As well as ranking among the very clearest waters in the world, these spring waters are virtually indistinguishable from pure water as regards their spectral irradiance attenuation in the ultraviolet and beam attenuation in the green region of the spectrum, undetectably low content of yellow‐coloured organic material, and remarkable blue‐violet colour.

ISSN:0028-8330    

DOI:10.1080/00288330.1995.9516658

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor