Phytoplankton biornass in relation to the surface hydrography of southern New Zealand and possible effects on the food chain

Abstract

The surface distribution of salinity, temperature, nitrate‐nitrogen (N0₃‐N), and chlorophyll a in the southern New Zealand, Foveaux Strait region in February 1977, 1978, 1979, and 1980 was highly variable. The source of new nitrogen appears to be incursions of high‐salinity water west and east of Stewart Island. Although it seems likely that the source of this high‐nutrient, high‐salinity water is vertical, a horizontal advective source cannot be ruled out The chlorophyll a content of surface waters was not related directly to the NO3‐N concentrations. This lower food chain variability may be linked to variability in economically important species. Oysters grew twice as fast in the summer of 1978/79 as they did in 1979/80. But the mean chlorophyll a values were very similar for February of both years (2.5 and 2.2 μg 1^?1, respectively). The elevated NO₃‐N levels in 1979 may have resulted in much higher phytoplankton levels later that summer and resulted in the higher oyster growth rate that year. The mechanisms driving this variability have yet to be determined.     

Diurnal variation in vertical distribution of pelagic copepods off Kaikoura,New Zealand

The vertical distribution of 55 species of copepods at levels 0–100 m, 100–250 m, 250–500 m, over 21 hours on 20–21 September 1967 at a station 39 km east of Kaikoura (central east coast), New Zealand, is reported, and changes in the night : day biomass ratio at the three depth levels are discussed.

Most copepod species counted showed diurnal vertical migratory movements generally similar to those recorded by other workers, but differences between sexes were noted. Modifications to the usual diurnal migratory pattern were observed and are thought to be caused by the animal's physiological state or by changes in the environment.

In the surface 250 m, the night : day biomass ratio was >2 but at 250–500 m it was <1.     

Summer distribution of the pelagic copepod Centropages aucklandkus in New Zealand waters

The quantitative distribution of Centropages aucklandicus in summer is described. This coastal species, endemic to New Zealand, is found round the whole country except in the north. It has a northern limit coincident with the 19°c isotherm. Possible factors operating to conserve C. aucklandicus in coastal waters, temperature, salinity, food and behaviour, are discussed.     

Archaeological geophysics investigation of the Wright Brothers 1910 hangar site

An archaeological geophysics investigation was conducted at the site of the Wright Brothers' 1910 hangar near Dayton, Ohio. The hangar was destroyed as part of base renovation during the buildup to World War II, and its exact location is unknown. The purpose of the investigation is to confirm the exact location of the hangar and to locate any buried artifacts from the Wright Brothers occupation of the site. Ground penetrating radar (GPR), electromagnetic, and magnetic surveys were conducted over a 68 × 100 m area, approximately centered on the suspected location of the hangar. Localized anomalies as well as areal anomalies are identified in the geophysical data. Rectangular anomalous areas are identified that are generally consistent with the suspected location of the hangar. A 1924 aerial photograph showing the hangar was digitally scanned and georeferenced to the site survey area. Two of the rectangular geophysical anomalous areas are consistent with the hangar location from the aerial photograph location. A third rectangular area, defined from GPR survey data, is immediately adjacent to the aerial photograph location. It is postulated that base engineers may have bulldozed the hangar debris onto an area adjacent to its original location and either burned it there or buried it in a trench. A prioritized exploratory program is proposed for investigating the sources of the geophysical anomalies. © 1994 John Wiley & Sons, Inc.