The role of the circadian time-keeping system in regulation of locomotor activity and certain aspects of reproduction has been investigated in wild Polynesian rats, Rattus exulans. Locomotor activity is under circadian control and data are consistent with a general model of the pacemaker mechanism as a weakly interacting population of circadian oscillators. Experimental studies and field observations indicate that the action of light in entrainment of this rhythm is primarily non-parametric. Female R. exulans continue to ovulate during prolonged periods in constant conditions and undergo a pattern of change in vaginal cytology through the estrous cycle which closely resembles that of laboratory R. norvegicus. These findings are consistent with the hypothesis that the estrous cycle in R. exulans is regulated by a similar circadian mechanism to that controlling the timing of ovulation, and hence the duration of estrous cycle, in laboratory rats. Female R. exulans do not exhibit regular fluctuations in either the period of the activity rhythm or intensity of the active phase in association with the estrous cycle. Ovariectomy also has no significant effect on the period of the activity rhythm and no discernible effect on the distribution or intensity of activity. It is therefore concluded that there is no feedback action of the ovaries or estradiol on the circadian pacemaker regulating locomotor activity in R. exulans, which thus differs from laboratory rodents. This proposition is further supported by the observation that there are no significant changes in either period or variability of the activity rhythm in association with the degenerative changes that occur in the female reproductive system in old age. The adaptive significance of these findings is considered. Field studies on breeding patterns of R. exulans throughout its distribution provide several lines of indirect evidence in support of the hypothesis that the onset of breeding in this species in temperate latitudes is regulated by seasonal changes in photoperiod. Accelerated attainment of puberty occurs in juvenile females collected during the non-breeding part of the year and housed in LD 16:8. Juvenile females collected at the same times but housed in LD 8:16 for an identical duration remain immature. Groups of mature females collected during the breeding season do not show a differential response to these light regimes. These results are discussed in relation to field data on breeding patterns in the population from which experimental animals were collected. It is concluded that the onset of breeding in this population is controlled primarily by a photoperiodic mechanism regulating the attainment of reproductive maturity in females. Information on the physiological organization of circadian systems in mammals is reviewed, with particular emphasis on the relationships between locomotor activity rhythms, the estrous cycle, and the effects of photoperiod on reproductive function in rodents.

The thesis answers the general question of whether the quality of artificially reared insect species should be based on performance tests for intended use or whether quality should be based on a more holistic biological approach. The empirical research is carried out using the lepidopteran leafroller 'Cnephasia' jactatana (Walker). The thesis defines biological performance and quality in terms of the success of an insect population in survival and reproduction and regards the laboratory environment as an artificial habitat that insects must colonise in order to survive and reproduce. Changes in biological performance that occurred during 12 successive generations of laboratory rearing were due to selection, acclimatisation and domestication and not adaptation. Artificial colonisation is theoretically successful within a limited range of environmental factors. As the inherent genetic variability of the founder population determines the resilience of the population to changes in performance, the ranges of environmental factors during colonisation should be wide to 'capture' much of the variability. Using body size (weight) as an aspect of overall quality, the thesis presents evidence that the final instar larva of C. jactatana has a threshold mechanism (larval critical weight, LCW) that determines pupal and adult size. There is a proportionate decrease in weight from the maximum weight that a larva attains in the final instar (LMW) to pupa ( described as constant DP ) and to adult (DA). There is a direct relation between the latent feeding period (period between attaining an LCW and LMW), LMW, pupal and adult size, and the reproductive performance (fecundity ). Within the experimental conditions diet quality, temperature, photoperiod and artificial selection had no effect on the larval critical weight, DP or DA, the larval threshold mechanism in C. jactatana is probably a mechanical trigger that initiates pupation. Diet quality, temperature and thermophotoperiods affected pupal size, adult size and reproductive performance. Photoperiod had no significant effects on size and reproductive performance. Positive assortative selections for slow development and low pupal weight significantly decreased pupal and adult size, and reproductive performance. Selection for fast development and heavy pupal weight for three generations had no significant effect on size or reproductive performance. Larval critical weight is demonstrated as useful to define quality indices and predict the performance of laboratory reared insects. The general conclusion of the thesis is that insect quality should be defined more in terms of the success in survival and colonising ability rather than solely on the success for 'intended role' or 'fitness for use'.

This thesis describes the behavioural ecology of the tui, Prosthemadera novaeseelandiae, a member of the Meliphagidae (honeyeaters), in the suburban Auckland region of the mainland of New Zealand. Tui are highly nectarivorous but observations show differences in degree of importance between the three food categories; nectar, fruit and insects according to season. when foraging for nectar tui are not responsive to flower colour but use all flowers with nectar concentrations greater than 7% (wt. per wt.) and use fruit when nectar availability falls. Foraging observations are significantly different for male and female tui with males taking more nectar and females taking more insects, in response to greater protein requirement as well as a result of status affecting foraging. There is also a seasonal difference in method of prey capture with the more energetically expensive hawking occurring in times of greater nectar availability or when very few insects in relation to nectar are taken. Colour-banded tui are shown to move in family groups over distances ranging from 5 to 35km in search of nectar for much of the year, but are localised into small foraging areas during breeding when nectar is abundant. Group members remain together and nest near each other, female offspring nesting closer to parents than male offspring. There is differential access to both natural and artificial food resources and the various asymmetries of sex, age and residency determine relative status at food sources but are not absolute. Loud song is the most conspicuous behaviour and is used to mediate avoidance between individuals and between groups. An artificial food source is partitioned temporally and spatially during breeding with the local higher status birds that use the feeders having significantly greater breeding success. Unlike results published for most passerines, both sexes of tui sing throughout the year and songs in their repertoire show sexual, seasonal, behavioural and individual variation. Pairs duet and both sexes will match songs with mates and with neighbours; resulting in apparent dialect areas corresponding with group boundaries. Avian spirochaetosis is identified as one of the causes of death in a population with 13-30% annual loss. Losses are readily compensated for as the nesting cycle is short and the breeding season is long. This, together with an opportunistic foraging strategy, great mobility and prolonged association in family groups explains the continued presence of tui in suburban areas.

Endogeneity of valve movement rhythms was demonstrated for the Pacific oyster Crassostrea gigas under constant conditions of temperature, light, salinity, water level and food availability. Rhythms continued for up to 6 weeks until the experiments were terminated. The rhythms showed a high degree of temperature compensation between 13 - 24˚C, but at 4˚C the free-running period was abnormally long. The length of the “open", or active phase decreased with temperature. Oysters collected from subtidal sites, as opposed to intertidal sites, also exhibited endogenous rhythms when held under constant condition. Oysters that received no food during a starvation trial were also rhythmic. Oysters subjected to artificial tidal cycles (HL 6:6h), show very precise synchronization of valve opening and closing to the cycles. Oysters were also be entrained to water disturbance cycles (6:6h) and light cycles (LD 12:12h), but the synchronization was not as precise. Rhythms were characterized by (1) split rhythms (2) spontaneous changes in the free-running period (3) spontaneous changes in rhythm clarity (4) spontaneous phase changes (5) and a Lot of "noise". These characteristics suggest that the underlying pacemaker controlling the rhythm may consist of more than one oscillator or more than one group of oscillators. No conclusive evidence could be found for semilunar or lunar rhythmicity. Cycles in the rate of algal cell clearance over a 24h period were shown by individual oysters. As a consequence of the variability between individuals combining the data tended to hide the existence of the rhythms. No evidence for rhythms in assimilation efficiency was found. Cell clearance rates were also affected by rising temperature over the range 4 - 25˚C, reaching a peak value at 17˚C. The rate of cell clearance fell sharply after 60 - 90min of feeding in a closed system, indicating that the rate was significantly affected by the decline in food availability. The time taken to open the valves and to start faeces production fell with increasing temperature. The amount of faeces production followed a similar trend. Assimilation efficiency fell with increasing temperature and many negative values were evident, suggesting contamination. However the total weight of faeces produced was less than that of food available implying that the oysters were assimilating inorganic material. The time taken to open the valves and the % oysters that opened their valves was adversely affected by declining salinity over the range 8.5 - 34‰. The time taken to start faeces production and. the % of oysters that produced faeces followed a similar trend. Assimilation efficiency was not significantly different at 25.5 and 34‰. AE% could not be measured at 8.5 and 17‰ due to a lack of normal faeces. Individual oysters showed cycles in the rate of oxygen uptake, but these were not synchronized to the tides or to each other. Pooling the data to calculate means cancelled out the individual rhythmicities. The presence or absence of food did not affect the expression of the cycle. The rate of oxygen uptake was positively correlated to oyster dry weight, temperature and salinity. Though for salinity the rate of oxygen uptake fell sharply below a critical salinity occurring between 10 - 13‰. Oysters held in sealed respirometers maintained a constant rate of oxygen uptake until a critical level of oxygen availability was reached, the rate of oxygen uptake dropped .significantly below this level. The slope of the regression lines (˚b˚), prior to reaching the critical oxygen level, increased with temperature, salinity and food concentration. But the time taken to reach the critical oxygen level, and the level of oxygen availability at which this occurred, was not significantly correlated with temperature, salinity or food concentration. The pattern of valve movement corresponded to the level of oxygen available. Valve movements became very frequent as the critical oxygen level was approached. Activity was reduced to occasional periods of valve movement after it was reached. The level of activity was adversely affected by declining salinity, but was not affected by the level of food availability.

Historical background: Study of plankton communities of New Zealand waters has been neglected in the past. The various expeditions which have collected in the area have mostly concentrated on dredging, shore collecting and bathypelagic programmes. Even the earliest expeditions, dateing from the voyages of Cook, recorded superficial observations of plankton organisms. However, the first serious observations were the descriptions by Dana (1850's), of pelagic crustaceans from the collections of the U.S. Exploring Expeditions (1840). Then in the winter of 1874, H.M.S. "Challenger" made a number of tow-nettings in the Tasman Sea and the reports of the expedition together comprise the first comprehensive account of the plankton of the area.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / The structure and function of benthic invertebrate communities in the Waitakere River, a kauri forest stream ecosystem, was studied in association with physicochemical parameters from May 1973 until March 1976. Emphasis was placed upon life histories of the dominant species, so that changes in community structure along the stream could be characterised. Analysis of vegetation along the forested watercourse showed a predominance of podocarps and kauri (Agathis australis) in the canopy, with tree ferns dominating in the subcanopy. As the stream flowed into open farmed areas, algal blooms, which were mainly present in summer in some forested sites, became more widespread and persistant. These appeared to influence the composition of the invertebrate communities. Physicochemical analyses of water from several sites in the Waitakere River and its tributaries (from January to December 1974, and in July 1975 and February 1976) provided no evidence that algal blooms could be associated with nutrients derived from agriculture. In the classification of Williams (1964) the waters were "calcium poor" (generally <8.0 g/m3) and intermediate between "soft" and "medium hard" (alkalinity 15-44 g/m3). However, they were comparatively rich in silica (14-35 g/m3), sodium (17-25 g/m3) and chloride (25-39 g/m3). The association between physicochemical variables was tested by correlation matrix analysis. Two distinct groups were formed. Group A variables (temperature, sodium, conductivity, alkalinity, hardness, chloride and potassium) were positively correlated with each other, but negatively correlated with precipitation, whereas group B variables (manganese, iron and sulphate) were positively correlated with turbidity. A summer groundwater influence appeared to provide maximum values for group A variables, and increased turbidity during high rainfall (winter) produced maximum values for group B variables. The invertebrate fauna was surveyed throughout the watershed, and studied intensively at four sites (two in open farmland and two in forest) for 12 months. Separation of most invertebrate groups to species level provided 144 taxa, almost three times the number in previously published faunal lists for New Zealand streams, but comparable with those obtained in the Northern Hemisphere. Aspects of the life histories of the following 19 taxa were investigated: Potamopyrgus antipodarum (Gastropoda : Hydrobiidae), Paracalliope fluviatilis, (Amphipoda : Eusiridae), Coloburiscus humeralis (Ephemeroptera : Siphlonuridae), Zephlebia nodularis, Atalophlebioides sepia, Deleatidium lillii, D. myzobranchia, Deleatidium sp C, Deleatidium sp E (Ephemeroptera : Leptophlebiidae), Zelandobius furcillatus (Plecoptera : Gripopterygidae), Hydora nitida (Coleoptera : Elmidae), Maoridiamesa harrisi,? Austrocladius sp., Paratanytarsus agameta (Diptera : Chironomidae), Austrosimulium australense (Diptera : Simuliidae), Aoteapsyche colonica (Trichoptera : Hydropsychidae), Oxyethira albiceps (Trichoptera : Hydroptilidae), Pycnocentrodes spp and Olinga feredayi (Trichoptera : Sericostomatidae). Most of these had poorly synchronised, indistinct life cycles which could not be classified using the system of Hynes (1970) for temperate Northern Hemi sphere streams The most diverse communities occurred in the rapidly flowing, cool tributaries of the Waitakere River, dominated by insects with long life cycles. Downstream the communities were dominated by non-insect species, or insect species with rapid life cycles and a seasonal occurrence. Many of these appeared to be associated with algal blooms. A black polythene artificial canopy (44 m2) was placed over an area of the lower Waitakere River prone to algal blooms, to investigate the effect of algal removal induced by shading. Groups which declined in abundance under the canopy were Chironomidae and Hydroptilidae, while drift filtering species (Aoteapsyche colonica and Austrosimulium australense) increased in number under the canopy. Other taxa (Pycnocentrodes spp., Potamopyrgus antipodarum and Elmidae larvae) remained equally abundant in shaded and non-shaded areas. The possible contribution of species colonizing such "new" habitats through drift and adult flight was investigated. Invertebrates of the Waitakere River and its tributaries differed from those of temperate Northern Hemisphere streams in taxonomic composition, trophic structure (relative lack of "shredding" species), life history patterns and the presence of spatial and temporal overlap of related species (members of the genus Deleatidium). It is suggested that most of these characteristics occur throughout New Zealand, and are related to the types of detritus entering New Zealand streams, and the effects of long geological isolation.

Forty-five species of harpacticoid copepod (twenty-eight of them new), from sixteen genera and seven families, are described from New Zealand. The species were collected from a wide variety of freshwater habitats as well as from coastal and inland brackish water bodies and from terrestrial habitats with thin water films. Two new genera, Australomoraria and Taneroa, are described from within the Family Canthocamptidae, a family which contains the majority of species, and the genus Antipodiella Brehm, 1928, is resurrected, Keys to families, genera and species are given where applicable. The origins and relationships of the freshwater harpacticoid fauna are considered, together with its ecological and geographical distribution within New Zealand. / Whole document restricted, but available by request, use the feedback form to request access.

The static and dynamic distribution patterns of ichthyoplankton were investigated over a 4 year period (1981 - 1985) off the coast of Leigh, on the northeastern coast of New Zealand. Emphasis was given to horizontal and vertical distributions, and these were described on scales encompassing broad areas of the outer Hauraki Gulf and smaller areas of 1 - 100m. The ages of these small fish were also investigated by examining daily increments in the otoliths, and this allowed a more complete interpretation of distribution patterns. Sampling that was carried out at different distances from the mainland identified major differences in the distribution patterns of individual species. For example, pilchards were caught in high densities right across the continental shelf, whereas morid cod were restricted to the outer edge of the shelf. The most intensive investigations were carried out over the Summer months and these revealed large differences in the abundances of species. For instance, few bothids and triglids were captured in December, while large numbers were caught in January. The spawning activity of adults and broad scale differences between water masses were probably responsible for these distance and time related patterns. Large differences in the densities of ichthyoplankton were found at different localities within each area of the continental shelf (e.g. close to the mainland). Furthermore, detailed investigations of abundances at a single locality over a three day period showed large changes. These changing distribution patterns were related to the dynamics of localized hydrological features (e.g. tidally induced gyres). The presence of islands over the continental shelf also influenced the distribution of small fish. Some species were only found near land, regardless of the distance from the mainland. From ichthyoplankton hauls and direct observations made using SCUBA, it is argued that the behaviour of ichthyoplankton may have a strong influence on their distribution patterns. For example, tripterygiids and gobiesocids of a variety of ontogenetic forms were observed to aggregate and maintain their position in the shallow areas of rocky reefs. Large differences were found in the vertical distributions of fish and this was true in water columns from 1 - 40m in depth. Ichthyoplankters of a number of species had different depth distributions. Some species were consistently found near the surface (e.g. hemiramphids & mugilids) or near the bottom (e.g. eleotrids). For species found throughout the water column during the day, it was suggested that biological and physical stratification (e.g. thermoclines) strongly influenced relative densities at each depth stratum. Some species (especially engraulids & scombrids) migrated toward the surface at night. Migration patterns varied for each species and among times. The latter patterns were related to ambient light levels which changed with the phase of the moon. Small scale structure in the pelagic environment influenced the distribution of fish. Large numbers of fish were found around drift algae and when experimental algae were left to drift, small fish of several species (e.g. Monacanthids) were quickly attracted to it. A number of species were abundant in surface waters, but did not associate with drift algae (e.g. engraulids). For fish that were found around drift algae, the association may be important as a source of shelter and food. There was considerable seasonality in the occurrence of fish species around algae, and the abundance of total drift algae. Drift algae were most abundant over Spring and early Summer. The movements and accumulation of algae are discussed in relation to the potential influence it has on recruitment patterns of fish in nearshore environments. The distribution patterns of small fish were strongly influenced by the surface slicks of internal waves. Densities of small fish, drift algae, and zooplankton were higher in slicks than in rippled water adjacent to them. Slicks moved at 0.5 - 1.25 km per hour in the direction of shore. A consequence of aggregation in slicks, therefore, is that small fish may be transported onshore. It is suggested that the accumulation of zooplanktonic food in slicks may be important for the feeding of ichthyoplankters. Many of the fish found in surface waters, be it in open water or around drift algae, had adult fin-ray counts and were not considered to be larvae, according to current definitions. From information on the age and size of these fish it is suggested that the capacity of fish to settle at a variety of ages and sizes has probably been underestimated. Furthermore, the occurrence of physical processes such as slicks may influence the duration of the planktonic phase and subsequent settlement rates of fish into nearshore environments. The major findings were used to provide an overall picture of what happens during the planktonic phase of some species (Chrysophrys auratus, Parika scaber & tripterygiids), and these case histories are discussed in relation to current hypotheses concerning the ecology of ichthyoplankton.

Despite advances of recent years no stable higher order classification of the Porifera has yet emerged. To address this problem, relationships at various taxonomic levels within the Order Hadromerida have been evaluated. Descriptions of new species of. Tethya, Aaptos and Polymastia from northern New Zealand are given in conjunction with a review and redefinition of specific diagnostic characters for these genera. A range of species, genera and families within the Hadromerida have been subjected to 18S rRNA sequencing. Using morphological and molecular sequence data together in phylogenetic analysis, the existing familial groups of the Hadromerida are confirmed and some rearrangement of genera is indicated following sequence alignment and comparison. These data serve as a baseline for molecular approaches to resolving relationships between other sponge groups. / Thesis now published as papers. Whole document restricted at the request of the author, but available by individual request, use the feedback form to request access.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / The fatty acid content of 30 species of Porifera, including samples of Hexactinellida and Lithistida for which no fatty acid data previously existed, have been examined. Sponges are unique among animal phyla in diversity of fatty acids with generally high levels of LCFAs (C24-30), high unsaturation (mainly polyunsaturation), and high incidence of branched and odd chain fatty acids. Further, peculiarities in the proportions of individual acids of particular chain lengths distinguish the phylum. Hexactinellid fatty acid traits corresponded closely to those of Demospongiae while the calcareous species was atypical in exhibiting comparatively low levels of LCFAs and unsaturation. Seasonal and geographical influences on components of the fatty acid profile limit the extent to which this information can be utilised in a chemotaxonomic sense. The major trends in seasonal variation of fatty acid content were in an increase in the levels of unsaturated fatty acids and a decrease in the levels of LCFAs during winter. The effects were less pronounced in a subtidal than intertidal species and are considered to be related to environmental temperature. LCFAs predominated in the phospholipids but also were present in high amounts in neutral lipids. The major changes in fatty acid content of the total lipid with season were reflected in the fatty acids of the phospholipids. Also, LCFAs were concentrated in cellular membranes of the sponge. Temperature-induced seasonal changes in LCFA and UFA composition could be explained as an attempt to maintain .the membranes from which these acids originate, in an optimal state of physico-chemical function across the environmental temperature range. This interpretation is supported by observation of an increased content of higher melting point lipids in the sponge in summer. The sensitivity of sponge membranes to temperature was demonstrated by thermal-induction of phase separations in membrane lipids. A major phase separation in both isolated lipids and membranes occurred within a ca. 8 °C of the normal growth temperature range of the sponge. It indicated that membrane lipids exist in a fluid state in the living sponge so that any variation in environmental temperature would affect the lipid fluidity of the membrane and hence physiological membrane processes. This also lends support for some control being exerted on the lipid fluidity of sponge membranes. Any such control must be non-behavioural since sponges are poikilotherms. Minor changes in the proportions of different phospholipids with season were indicated and are also likely to affect the physical properties of membranes which contain them. In general, the lipid yield from sponges as a proportion of the total dry weight is highly dependent on the skeletal composition, specifically the ratio of the structural to living tissue. Therefore lipid yield is not a reliable parameter for classifying sponges. The occurrence of terpenoid metabolites has proved more informative taxonomically and characterised those groups with a low sterol content, e.g. Dictyoceratida. A coincidence of occurrence of terpenoids and high levels of C25 of fatty acids was noted.