INCIDENTAL CATCH OF HECTOR'S DOLPHIN IN INSHORE GILLNETS

The incidental catch of Hector's dolphins (Cephalorhynchus hectori) in gillnets in Pegasus Bay and Canterbury Bight, New Zealand is assessed. From 1984 to 1988, at least 230 Hector's dolphins were killed in groundfish gillnets by commercial and amateur fishermen. Approximately 91% of entanglements occurred from November to February. Seasonality of catch corresponded to increased commercial gillnetting inshore in spring and summer. Most entanglements (89%) occurred within 4 nautical miles (7.4 km) of the shore, and most dolphins (86%) were caught in water less than 20 m deep. The dolphin's summer inshore movement also coincided with high levels of inshore gillnetting by amateur fishermen. The age-frequency of net-caught dolphins suggested that young animals were particularly vulnerable to entanglement.     

SURVIVAL RATES OF PHOTOGRAPHICALLY IDENTIFIED HECTOR'S DOLPHINS FROM 1984 TO 1988

Re-sightings of photographically identified individuals were used to estimate survival rates for a free-living population of Hector's dolphins Cephalorhynchus hectori , a species endemic to New Zealand waters. Most individuals were identified from injuries to the dorsal fin. Consequently, the photographic catalog contained very few young individuals. Our analysis included no newborn calves or yearlings, and provided estimates of survival rates only after the first year of life. We used two complementary methods for calculating survival rates: a modified Jolly-Seber model, and a simpler method which corrects in a more explicit way for individual dolphins being alive but not sighted. Selection of the most reliable subset of the data had a greater effect on computed survival rates than did the difference between the two methods. We conclude that careful inspection of resighting data before analysis, and, if necessary, selection of a subset, is very important in studies of this kind. Survival rate estimates came from a population which was subject to relatively heavy mortality from gillnet entanglement. Standard errors of the survival rate estimates have been used to assess the conditional probability of population decline given three fertility scenarios. The high probability that the Banks Peninsula Hector's dolphin population was decreasing during the study period (0.78 to 0.99) suggests that gillnet entanglement constituted a serious risk to this population.     

<Emphasis Type="Italic">Coprinopsis austrophlyctidospora</Emphasis> sp. nov., an agaric ammonia fungus from Southern Hemisphere plantations and natural forests

A new ammonia fungus, Coprinopsis austrophlyctidospora, is described from Nothofagus and Pinus forests in New Zealand and from Eucalyptus forest in Australia. In ecology and macro-morphology, this species is similar to the Northern Hemisphere species C. phlyctidospora, but the new species differs in morphological characters of the basidiospore, i.e., in having a plage, more minute surface warts, and the smaller size of the basidiospore.     

Assessing the ecological value of small testate amoebae (<45 μm) in New Zealand peatlands

Methodological advances are essential for robust ecological research. Quantitative reconstructions of environmental conditions using testate amoebae rely on sound taxonomy. While the taxonomy of large species is relatively well resolved, this is not the case for most small taxa (typically <45 μm long). In New Zealand, peatlands contain a diversity of both cosmopolitan and characteristic large southern endemic taxa, but also have a high abundance of small taxa. The latter are often lumped into morphotypes reducing their value as ecological indicators. In this study, we demonstrate how (a) lumping small taxa versus splitting them into unique types, and (b) including or excluding them from community analysis influenced their ecological inference. We assessed testate amoeba composition in six peat bogs from New Zealand, three that were moderately-to-highly impacted, and three that were non-impacted. Environmental variables were measured at each sampling site and the surface testate amoeba community patterns and community-environment relationships compared. We found a clear division between impacted and non-impacted sites. Several distinct small taxa were more strongly related to water-table depth and conductivity, while the larger taxa were more correlated to pH. These results show that improved taxonomic resolution of small taxa can provide more informed environmental assessment.     

Testing for seasonality in alpine streams: How does altitude affect freshwater insect life cycles?

1. Altitudinal offset in adult emergence has been well characterised for terrestrial insects, but remains poorly understood for freshwater insect assemblages. Stream insects, like their terrestrial counterparts, are expected to exhibit phenology gradients, with delayed emergence associated with increasing altitude (Hopkins' Law).
2. We analysed the collection records of the entire endemic stonefly fauna from New Zealand's mainland (99 species, 19 genera, four families) to test for intraspecific and interspecific correlations between altitude and adult emergence.
3. Intraspecific analyses of widespread New Zealand plecopteran taxa indicate that high‐altitude populations emerge substantially later than those at lower elevations, with 25 of 31 widespread stonefly taxa yielding significant positive associations between altitude and emergence date. Similar patterns were detected for interspecific comparisons, even when phylogenetic relationships were considered, with high‐altitude taxa emerging substantially later than lowland counterparts.
4. In a number of species, delays in emergence (mean: 5.3 ± 2.0 days/100 m) exceeded those previously reported for terrestrial insect taxa and also exceeded values originally predicted under Hopkins' Law. These findings suggest that stream‐insect life cycles have potential to be highly sensitive to temperature shifts and thus raise questions about their response to anthropogenic climate impacts.