摘要:

Description of striped trumpeter(Latris lineata(ForsterinBloch and Schneider 1801)) eggs and larvae, previously described in summary only, is provided and illustrated from laboratory‐reared material. Laboratory fertilised eggs are round, 1.26–1.44 mm diameter, with a single, pigmented oil globule 0.27–0.29 mm diameter in an unsegmented yolk. Early‐stage embryos are pigmented on trunk and tail dorso‐laterally, forming a dorsal and ventral pigment band in late‐stage embryos. Hatching occurs 7–8 days post‐fertilisation in 12°C. Larvae are 2.8–3.5 mm body length (BL) at hatching with a voluminous finfold, large yolk sac with centrally‐placed oil globule, distinct pigmentation pattern, and no head spines. Flexion occurs from 5.6 to 8.7 mm BL. Fin formation commences from 6.6 mm BL in the sequence caudal, dorsal and anal (simultaneously), pectorals and pelvics. Myomeres number 33–39. Larvae are pigmented predominantly on the head, dorsal and ventral surfaces of trunk and tail, and gut ventrally, with melanophores also on upper and lower jaws. Larvae survived to 45 days post‐fertilisation, 11.9 mm BL, with complete fin‐formation of the caudal fin only. Similarities are noted betweenL. lineatalarvae and aplodactylid, bovichtid, cheilo‐dactylid, chironemid, sillaginid, and tetragonurid larvae. A small number ofL. lineatalarvae were also caught inshore and at shelf edge on the Tasmanian west coast in late winter/early spring (September/ October).

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516865

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Litter fall was measured at two intertidal levels within two stands of the mangroveAvicennia marina(Forsk.) Vierh. var.australasica(Walp.) Moldenke in Rangaunu Harbour, New Zealand (34° 57'S, 173° 15'E). The seasonal pattern of litter fall was typical ofA. marinaat high latitudes. Flowering occurred in March‐April and fruit fell 9 months later during December‐January. Leaf fall was highest from November to February and was positively correlated with temperature and negatively correlated with sediment water availability (total rainfall minus total evaporation). Total annual litter fall ranged from 1.81 ha‐1yr‐1to 6.21 ha‐1yH and was proportional to mean tree height at each site. Leaves constituted on average 73% of the total litter fall and were the only litter component to show significantly lower magnitude at both elevated sites. The largest litter collections were made during the summer months coincident with peak falls of leaves and fruit. The possible contribution of mangrove litter to es‐tuarine food chains in northern New Zealand estuaries is discussed.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516866

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The rates of photosynthesis of the seagrassSyringodium isoetifolium(Aschers.) Dandy were measured by a gas‐release technique with whole shoots incubated in the field. Greater than 95% of the variation of the photosynthetic data could be accommodated by the Photosythesis‐Irradiance (PI) model presented here. As expected, the shape of the Pi‐curves differed between shoots. The different shapes resulted from the different photosynthetic maxima and the efficiency with which shoots used light but not the amount of light required by the shoot to reach saturating light intensities. Irrespective of the units (whole shoot, leaf chlorophyll content, or leaf surface area) used to generate the PI‐curves, there was no significant(P >0.05) difference between saturating light intensities (Ik), the mean value was 180 ± 33 μmol m‐2s‐1. The quantity and quality of light available to these plants can modify leaf surface and chlorophyll content of seagrass shoots. Presenting the rates of photosynthesis as a function of chlorophyll or leaf surface area diminishes the ability to observe differences between plants. Hence, the health of seagrass plants may be more obvious and quantifiable if seagrass productivity data are expressed as a function of whole seagrass shoots rather than on the basis of chlorophyll content or leaf surface. During the 20‐day study, the photoperiod ranged from 6.2 to 10.8 h and gross productivity estimates ranged from 10 to 18 g C day‐1m‐2. These estimates were more than 10 times greater than thein situnet leaf daily productivity of 0.9 g C day‐1m‐2that was measured with a traditional leaf marking technique. This result implies that most of the production was directed below ground. The health of seagrasses is related to the productivity of the whole plant not just the tissue that appears above ground. In comparative studies that are used to determine the habitat requirements of seagrasses and the impacts of pollutants on seagrass survival whole plant productivity measurements would appear to provide a better indicator of seagrass health.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516867

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Stable carbon and nitrogen isotopes have been used to characterise sewage discharge and effects on seaweed(Ulva lactucaL.), blue mussels (Mytilus galloprovinialis), and limpets(Cellana denticulata)from Moa Point Bay, New Zealand. The nitrogen (15N/14N) ratio is shown to be a good tracer of sewage pollution inUlva lactucaand associated grazers (Cellana denticulata)as a result of the increased contribution of urea and ammonia to the surrounding marine environment from the sewage outfall. The carbon (13C/12C) ratio is suggested as a more appropriate sewage tracer for mussels(Mytilus galloprovinialis), which filter feed the particulate organic matter from the effluent. Lower carbon : nitrogen ratios were found inU. lactucasampled from the outfall region, compared to uncontaminated control sites, however carbon: nitrogen ratios do not vary significantly amongst shellfish species.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516868

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Arenigobius bifrenatus(Kner 1865) is a burrowing coastal and estuarine goby from temperate areas of Australia. One specimen was captured from the Whangateau Harbour, north‐eastern New Zealand, on 1 April 1998, constituting the first record of this species from New Zealand. Further intensive beach seining at Pollen Island, within the Waitemata Harbour (Auckland), yielded two further specimens which were females in breeding condition. We suggest that the species is an adventive, and its presence in northern New Zealand waters is the result of accidental transport in shipping ballast water.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516869

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The day‐time cover preferences of three size groups (small = <100; medium = 100–199; large = 200–299 mm total length (TL)) of juvenile shortfinned eels(Anguilla australis)and longfinned eels(A. dieffenbachii)were tested during summer in replicate channels provided with natural (macro‐phytes, woody debris, cobbles) and artificial (shade, plastic pipes) cover types. Tests on the longitudinal distribution of all three size groups of shortfinned eel (with no cover in the channels) revealed no significant bias in the distribution of small and medium eels, but did so for large eels which favoured the ends of the channels. Similar bias occurred in the actual cover preference tests, which was adjusted for by the Poisson log‐linear model used in analysing the data. When the species were tested separately, small and medium eels of both species preferred cobbles and macrophytes more or less equally, whereas large eels showed a clear preference for macrophytes and a minor attraction for cobbles. When tested together, species cover preferences differed significantly, with a greater proportion of all sizes of longfins in the cobbles and shortfins in the macrophytes and woody debris. Artificial cover was an unattractive alternative to natural cover for all sizes of both species of eel. The results of these experiments suggest that both size and species interactions influence the distribution of juveniles of both species in the wild.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516870

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Rainbow trout(Oncorhynchus mykissRichardson) and chinook salmon(O. tshawytschaWalbaum) fry and 0+ fingerlings entered Lake Coleridge, a deep, oligotrophic lake in the Southern Alps of New Zealand, in spring and early summer and dispersed throughout the shallow littoral. In contrast, most juvenile brown trout(Salmo truttaLinnaeus) remained in the tributaries for 1–2 years before migrating down stream to the lake. Juvenile salmonids (<35Omm) were more abundant in the shallow littoral (<10 m), especially near tributaries, than in the deep littoral (10–40 m), or the surface layers (0–16 m) of the limnetic zone which were populated by yearling (>150 mm) and adult salmon and rainbow trout (>210 mm). The abundance of 0+ rainbow trout in the littoral zone declined rapidly from February to August and stocks were supplemented by a migration of yearling fish from the tributaries in spring. The shallow littoral zone and tributaries are both important for juvenile trout rearing in this lake.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516871

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Rates of mass loss are important in the choice of tree species used in riparian rehabilitation because leaves that break down fast should contribute to stream food‐webs more rapidly than leaves that break down more slowly. To examine comparative mass‐loss rates of some native evergreen and introduced deciduous trees in a New Zealand stream, fallen leaves were incubated in bags with 2×3 mm mesh openings. The native trees were mahoe(Melicytus ramiflorus), kahikatea(Dacrycarpus dacrydioides), silver beech (Nothofagus menziesii), rewarewa(Knightia excelsa), tawa(Beilschmiedia tawa), and the introduced trees were silver birch(Betula pendula)and alder(Alnus glutinosa). The leaf bags were left in the Mangaotama Stream for 28 days from mid April to mid May 1995 when mean water temperature was 14.5°C, giving a total of 406 degree days. Rates of mass loss followed the sequence: mahoe > silver birch > alder > kahikatea > silver beech > rewarewa > tawa. Mean mass‐loss rate for mahoe, assuming a negative exponential model, was 0.0507kday‐1(0.00350k(degree day)1), and for tawa was 0.0036kday‐1(0.00025k(degree day)1). C:N ratio decreased on average from 45:1 to 35:1, and δ15N increased between 0.7 and 3.0‰ (1.8 ± 0.41%o, mean ±1 standard error), excluding kahikatea. Changes in δ13C were smaller and not consistent in direction. Biomass of invertebrates was greatest in bags that had lost 25–45% of their initial leaf biomass.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516872

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The habitats used by shortfinned eels(Anguilla australis(Richardson)) in Lakes Ellesmere (Canterbury) and Waahi (Waikato), New Zealand, were determined using a variety of capture techniques during the summers of 1994/95–1997/98. The most successful technique used to catch juvenile eels (<300 mm total length (TL)) in Lake Ellesmere was a 2‐m wide beam trawl; larger eels were captured mainly by fine‐meshed fyke nets. Trawl catches during the night exceeded catches during the day by a factor of 2.4. In Lake Ellesmere, juvenile eels were mainly caught in the depth range 0.6–1.2 m, on a gravel and/or mud substrate, and within 1 km of the shore. In contrast, larger eels (>300 mm) preferred sandy substrates, but showed no marked preference for particular depths or distances offshore. The spatial distribution of both size groups was non‐random. Although water temperature did not influence catch rates (CPUE, catch‐per‐unit‐effort) of either size group, catches of the smaller eels were greater during the new moon phase than during the other phases—catches of larger eels were unaffected by lunar phase. Length‐frequency distributions of eels from Lake Ellesmere were strongly bimodal, with eels 200–300 mm poorly represented—this probably reflects poor recruitment for several years, either because lake opening times did not coincide with the availability of glass eels, or because overall numbers of glass eels were low. Juvenile eels in Lake Waahi, caught in fine‐meshed fyke nets and in special brush collectors, were also inshore residents; unlike Lake Ellesmere, juvenile eels could be caught at the lake margins, probably because Lake Waahi is not subject to the same wind‐induced water level fluctuations as Lake Ellesmere. Recruitment into Lake Waahi commenced in mid December, but there was evidence of low recruitment in past years for this lake also. An important outcome of this research is that estimates of the number of juvenile eels to be transplanted during stocking programmes should be made using the area of the shallow littoral rather than the area of the whole lake.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516873

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The arrival season of glass eels of both New Zealand species of freshwater eel, the short‐finned eel(Anguilla australis(Richardson)) and the longfmned eel(A. dieffenbachii(Gray)), was studied by electric fishing of 13 streams/rivers throughout east and west coasts of both North and South Islands at 14‐day intervals. Sites were usually located at the most downstream riffle exposed at low tide, and sampled by single‐pass electro fishing. The species composition was dominated by shortfins, with exceptions being west coast sites, one in the North Island and two in the South Island. From a comparison of species proportions in adjacent catchments, it was concluded that glass eels make choices about entry in particular water‐types. As the stage of pigmentation advanced during the arrival season, “early stage” glass eels were defined and densities of these compared to show seasonal arrival patterns—densities were generally low in August, highest in September‐October, and declined during November‐December. Patterns of arrival varied from almost continuous in some streams to “intermittent” in others. Longfmned glass eels preceded shortfinned glass eels, and probably arrived in the North Island before the South Island; shortfinned glass eels showed the opposite trend. Possible migration routes to New Zealand are discussed.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516874

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor