Phosphorus and nitrate run‐off in hill pasture and forest catchments,Taita, New Zealand

Abstract

Phosphorus and nitrogen were measured in stream run‐off from the four catchments of the Taita Experimental Basin (41° 11′ S, 174° 58′ E). The land is used as exotic conifer forest, native forest, and hill pasture. Multiple regression analysis was used to estimate chemical losses per unit area in floods and at low flows.

At low flows, the hill pasture (fertilised with lime at 630 kg·ba^?1·y^?1, and superphosphate at 380 kg·ha^?1·y^?1) tended to lose more phosphorus and nitrate than the forested land, but differences were small, and not always significant. During large floods, the hill pasture (No. 5 Catchment) lost about 3 times as much reactive phosphate and 2–5 times as much total phosphorus as the forested land, and 130–190 times as much nitrate as land in the Exotic Forest and Native Forest 2 Catchments. Nitrate losses from land in the No. 4 Catchment (mainly native forest) were as high as those from the hill pasture, so high nitrate loss is not associated solely with agriculture.

Losses of total phosphorus via the catchment streams were estimated as: No. 5 Catchment (hill pasture), 293 g·ha^?1·y^?1; Native Forest 2 Catchment, 201 g·ha^?1·y^?1; No. 4 Catchment, 124 g·ha^?1·y^?1; Exotic Forest Catchment, 71 g·ha^?1.y^?1. Nitrate‐N losses were estimated to have been 1356 g·ha^?1·y^?1, 11.5 g·ha^?1·y^?1, 1436 g·ha^?1·y^?1, and 44 g·ha^?1·y^?1 respectively. Phosphorus and nitrate concentrations were similar in the Exotic Forest and Native Forest 2 streams, but the Exotic Forest tended to lose smaller amounts because it yielded about 50% less water per unit area.

Over the 2‐y study, an estimated 47–70% of phosphorus losses and up to 83% nitrate losses occurred in large floods; 31% and 48% respectively were apparently lost from the hill pasture catchment in a single flood. Less than 20% of estimated phosphorus losses and as little as 1% of nitrate losses occurred at low flows.

Run‐off of phosphorus and nitrate was spasmodic, and this should be considered in assessing the impact of surface run‐off on the biology and chemistry of receiving waters.     

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.     

Parasitic barnacles (Cirripedia: Rhizocephala) from New Zealand off‐shore waters

Nine genera and species of rhizocephalans were recorded from the off‐shore waters around New Zealand. Mitochondrial and nuclear gene sequences were used to examine base differences between the European and New Zealand species of Parthenopea. Serial sections to study the internal structures of the reproductive organs were made for the genera Thylacoplethus and Thompsonia. Two species, Parthenopea australis n. sp. and Thylacoplethus novaezealandiae n. sp. are new to science and described in detail. Parthenopea australis n. sp. is the first rhizocephalan species recorded from the vicinity of active cold seeps. Three rhizocephalans could not be identified as they were parasitised by hyperparasitic cryptoniscine isopods. The decapodhost species comprised the taxa Paguridae, Lithodidae, Galatheidae, Chirostylidae, and Callianassidae.     

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.     

Icebergs south‐East of New Zealand in 1967 (note)

Sightings of 85 icebergs south‐east of New Zealand in February and March 1967 are reported, with associated sea surface temperatures.     

Spawning hoki (Macruronus novaezelandiae Hector) concentrations in Cook Strait and off the east coast of the South Island,New Zealand,August‐September 1987

Abstract

In September 1986, dense concentrations of freshly spawned hoki (Macruronus novaezelandiae) eggs were located in eastern Cook Strait. A follow‐up exploratory trawl survey of Cook Strait and the east coast of the South Island, in August and September 1987, located concentrations of spawning hoki in canyon features in Cook Strait, off the Kaikoura coast, and off Banks Peninsula. The largest concentration, 14 km long, 4 km wide, and up to 150 m thick occurred in Cook Strait Canyon, with catch rates of hoki up to 48 t h^?1. Gonad conditions of male and female hoki showed they were actively spawning. Catch rates in Cook Strait Canyon were comparable to the main fishery on the west coast of the South Island but were much lower off Kaikoura and Banks Peninsula. Hoki associated with spawning concentrations were not feeding. Bycatch species were mostly ling (Genypterus blacodes) and spiny dogfish (Squalus acanthias), and both were preying on hoki. Spiny dogfish were also feeding on spawned fish eggs. The possible stock structure of hoki is discussed.     

Occurrence of gravel in the stomachs of two New Zealand stream‐dwelling fish (note)

Gravel occurred in. the stomachs of 17.8% of 924 Galaxias vulgaris and 2.8% of 430 Philypnodon breviceps taken from the Glentui River, Canterbury, between June 1970 and November 1971. It is suggested that differences in feeding habits and feeding locality are responsible for the difference in occurrence of gravel in the stomachs of the two fish species. Galaxias vulgaris feeds in the water column in riffles and, being a drift feeder, is more likely to ingest inedible material by accident than is P. breviceps, which feeds on the bottom in sheltered or quiet stretches of the river.     

Further evidence for the existence of sub‐littoral populations of toheroa,Amphidesma ventricosum Gray (eulamelli‐branchiata), off the west coast of New Zealand

The finding of shells of toheroa (Amphidesma ventricosum Gray) which had been drilled by gastropods absent from the littoral zone, is presented as evidence for the existence of sub‐littoral populations of toheroa.     

New records of distribution and co‐occurrence of freshwater calanoid copepods in New Zealand (note)

Calamoecia lucasi was found with Boeckella propinqua in the Kaihoka Lakes, Nelson, and Boeckella hamata with Boeckella triarticulata in Lake Elterwater, Marlborough. These are the first records of C. lucasi in the South Island, New Zealand, and of B. hamata co‐occurring with B. triarticulata.     

Early recoveries of fin‐clipped quinnat Salmon in New Zealand (note)

Early Marine Department records (1930–42) show that of about 100,000 parr, of quinnat salmon Oncorhynchus tshawytscha (Walbaum), fin clipped at the Marine Department's Hakataramea Salmon Hatchery in south Canterbury, only 3 were positively recovered; later independent readings of scales from these fish agreed with the known age. A further 11 scale samples (for 1937 and 1939) of fin clipped fish have been read, but details of their recovery and of their fin‐clip combinations cannot be found. Thus, from approximately 100,000 fin clipped parr, only 14 recoveries can be substantiated.     

Melanistic southern right‐whale dolphins (Lissodelphis peronii) off Kaikoura,New Zealand,with records of other anomalously all‐black cetaceans

Reports of anomalously pigmented cetaceans, including melanistic (all‐black) individuals are infrequent. We observed four melanistic southern right‐whale dolphins (Lissodelphis peronii) including a calf, off Kaikoura (42°34'S, 173°50'E), New Zealand. We also compiled records of melanistic individuals from five other species of cetaceans. The ecological context of melanistic pigmentation of cetaceans is not well understood; however, it may increase heat absorption, affect ability to capture prey, impair visual/social communication, and/or increase conspicuousness to predators.     

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.     

Within‐colony variation in skeletal mineralogy of Adeonellopsis sp. (Cheilostomata: Bryozoa) from New Zealand

Three colonies of the erect, robust branching, cheilostome bryozoan Adeonellopsis sp. were collected from Doubtful Sound, New Zealand, to investigate within‐colony variation in carbonate mineralogy. One‐hundred‐and‐twenty‐one sections from 9 branches were found to contain mostly aragonite, with calcite ranging from 1.1 to 7.3 wt% (mean ± SD = 2.4 ± 1.2 wt%, n = 120). The magnesium (Mg) content in calcite ranged from 5.3 to 13.1 wt% magnesium carbonate (8.8 ± 1.0 wt% MgCO₃; n = 120). Calcite content decreased with increasing age proximally along the branch, indicating that secondary thickening is achieved with aragonite. In contrast, an oscillating trend in Mg content along branches suggests that seasonal or interannual environmental parameters may influence this geochemical parameter. Mineralogical variability highlights the need for multiple samples from the same colony to be measured when determining quantitative carbonate mineralogy in bryozoans. Bimineralic bryozoans such as Adeonellopsis sp. may have lower preservation potential than monomineralic bryozoans, and consequently may not survive diagenesis to become fossils. Bimineralic species may also be more vulnerable to dissolution pressure and possible ocean acidification than monomineralic calcitic taxa.     

First identification of the cylindrospermopsin‐producing cyanobacterium Cylindrospermopsis raciborskii in New Zealand

Cylindrospermopsis raciborskii is a planktonic freshwater cyanobacterium that is becoming increasingly prevalent in water bodies worldwide. During a survey of toxic cyanobacteria in New Zealand, C. raciborskii was identified in a sample collected from Lake Waahi (Waikato). This is the first identification of this species in New Zealand. Liquid chromatography‐mass spectrometry and liquid chromatography‐tandem mass spectrometry were used to confirm the presence of the cyanotoxins cylindrospermopsin (CYN) and deoxy‐cylindrospermopsin (do‐CYN). Detection of CYN and do‐CYN demonstrates that C. raciborskii is a now a species of concern in recreational, stock drinking, and potable water supplies in New Zealand.     

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.     

Stock structure of bluenose (Hyperoglyphe antarctica) off the north‐east coast of New Zealand based on the results of a detachable hook tagging programme

In late 1987, bluenose (Hyperoglyphe antarctica) were tagged with streamers attached to fish hooks, at six commercial fishing grounds between Gisborne and Cape Palliser, New Zealand. The tagged hooks were fished on commercial trot lines, but were attached with traces of 5.5 kg breaking strain nylon that broke when the fish took the hook and struggled to escape. Based on catches from full strength control lines fished simultaneously with the detachable gear, 1971 bluenose were tagged. In the subsequent 8.5 years, 44 tagged bluenose (where both the sites of tagging and recapture where known) were recaptured. All but seven of these returns occurred in the first year after tagging, indicating that the rate of long‐term tag retention was not good. Bluenose appeared to be relatively sedentary in the short term, but were capable of quite rapid and extensive movement. Four tagged fish had travelled distances in excess of 450 km, with movements to both the north and south of the tagging area. These data indicate that bluenose off the eastern coast of New Zealand between North Cape and Kaikoura probably comprise a single biological stock.     

Geographic and sex‐specific variation in growth of yellow‐eyed mullet,Aldrichetta forsteri,from estuaries around New Zealand

Survival and reproductive rates in fish are often a function of body size. Consequently, spatial‐ and sex‐specific variation in somatic growth rates can have important consequences for population growth and resilience. We used otolith‐based approaches to estimate geographic‐ and sex‐specific growth rates of yellow‐eyed mullet (Aldrichetta forsteri) collected from 14 estuaries and harbours around New Zealand. Aldrichetta forsteri is an abundant and dominant component of New Zealand's estuarine fish fauna. We extracted otoliths from 511 fish, validated daily and annual increments, and prepared transverse thin sections of otoliths to determine age. “Size‐at‐age” relationships were estimated using both linear‐ and non‐linear (von Bertalanffy) growth models, and model performance was evaluated using Akaike's Information Criterion. Because growth rates of sampled fish were best approximated by linear functions, we used ANCOVA to test the null hypothesis that growth rates of A. forsteri were homogeneous between sexes and among geographic locations around New Zealand. Our analyses suggest heterogeneous growth rates between sexes and among locations. Interestingly, relative growth rates between sexes appeared to vary across separate latitudinal gradients for North Island and South Island. Within each island (but not across islands), female A. forsteri generally grew faster than males at the lowest latitudes; relative growth rates of females declined progressively below males with increasing latitude.     

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.     

Plankton of lake Ototoa,a sand‐dune lake in Northern New Zealand

The seasonal cycles of abundance of the phytoplankton and zooplankton in Lake Ototoa, Northland, at 36° 31 S, 174° 14 E, are described. Concentrations of chlorophyll a were low (range 0.04–4.61 mg.m^‐3; mean 0.97 mg.m^‐3), and highest values were in winter. Phytoplankton densities were also low; an oligo‐trophic diatom‐desmid assemblage associated with Botryococcus, Dinobryon, and Svhaerocyslis was found.

The zooplankton was dominated by the calanoid copepod Calamoecia lucasi whose numbers remained fairly constant throughout the year, and the only other copepod found was the cyclopoid Mesocyclops leuckarti which was present in very low numbers. Bosmina meridionalis was the only limnetic cladoceran and was most abundant during autumn and spring. A number of rotifer species were also common.     

Physico‐chemical features of lake Ototoa,a sand‐dune lake in northern New Zealand

Lake Ototoa is a warm monomictic lake at 36° 31’ S, 174° 14'E. During a year's study (March 1969‐March 1970), the lake became thermally stratified in November, the metalimnion being between depths of 12 m and 16 m. Surface temperatures ranged between 10.2°c (in August) and 25.2°c (in late January), and bottom temperatures between 9.7°c and 17.5°c. The annual heat budget was calculated to be 642 354 KJ.m^‐2 (15 500 cal.cm^‐2) and the work of the wind in distributing the heat income 1.730 KJ.m^‐2 (1766 g.cm.cm^‐2). Secchi disc transparencies ranged between 5 m and 9.2 m (mean 7.07 m) and were greatest in the summer. Light transmission per metre was also high, ranging between 61% and 87%. Surface waters were normally supersaturated with oxygen, but during summer stratification oxygen concentrations in the bottom waters dropped to a minimum of 2.3 mg.litre^‐2 and a positive heterograde distribution of oxygen with depth was found. The oxygen deficit was 0.015 mg.cm^‐2.day^‐1 and showed the lake to be oligotrophic. Mean surface pH was 7.82, and the ionic composition of the waters was similar to that of other small New Zealand and Australian lakes located near the sea. Compared with other New Zealand lakes PO4‐P concentrations (range 1.00–10.20 μg.litre^‐1) were low and NO3—N concentrations (range 0.12–0.60 mg.litre^‐1) high.