Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Spatial variation in environmental conditions can elicit predictable size and morphological responses in marine organisms through influences on physiology. Thus, spatial and temporal variation in marine organism size and shape are often used to infer paleoenvironmental conditions, such as dissolved oxygen concentrations. Benthic foraminifera commonly serve as a tool for reconstructing past ocean oxygen levels. For example, benthic foraminiferal species assemblages, within‐ and among‐species patterns of test morphology, and geochemical analyses of carbonate tests are often employed to reconstruct past marine conditions. In this study, we measured the sizes and shapes of modern foraminifera representing four species that inhabit a steep oxygen gradient in the Santa Monica Basin on the Southern California Borderland with the aim of quantifying the influence of oxygen availability on foraminiferal morphology, both within and among species. Most foraminifera rely on aerobic respiration, but the four benthic foraminifera from the Santa Monica Basin do not show the predicted size and morphological responses to variations in dissolved oxygen concentrations based on first principles of cell physiology: Bolivina spissa shows no volume or volume‐to‐surface area response, Uvigerina peregrina increases in both test volume and volume‐to‐surface area ratio with decreasing dissolved oxygen concentrations, and both Bolivina argentea and Loxostomum pseudobeyrichi decrease in test volume, but only L. pseudobeyrichi shows a decrease in test volume‐to‐surface area ratio with decreasing oxygen concentrations as expected from physiological predictions. These findings imply that the morphological responses of individual foraminiferal species are not necessarily representative of the responses of other foraminiferal species within the community. Our findings further suggest that these species use physiological strategies such as depressed metabolic rates and alternative energy metabolisms to persist in low oxygen environments and, therefore, cannot be used in any simple way as paleo‐oxygen indicators. Should Proterozoic (1,000–542 million years ago) protists have possessed metabolic strategies similar to foraminifera, the sizes and shapes of protists in the fossil record may not usefully constrain ambient oxygen conditions during the appearance and initial taxonomic radiation of heterotrophic eukaryotes.     

天津地区含水层类型判别与参数分析

根据含水层数学模型的降深-时间双对数和半对数曲线特征,可以确定含水层类型;依据选定的含水层模型,调整其中水文地质参数以拟合抽水试验中观测井降深-时间实测数据,可以反演水文地质参数。将以上方法应用于天津地区6组工程抽水试验,获得试验含水层类型及其水文地质参数。该方法可用于其他相关工程,天津地区和工程建设有关的50m埋深范围内含水层属性及其水文地质参数取值范围,可参考借鉴本文计算结果。     

Comparative descriptions of some oyster larvae from New Zealand and Chile,and a description of a new genus of oyster,Tiostrea

Detailed comparisons of the larvae of four species of New Zealand oyster (Saccostrea glomer‐ata, Crassostrea gigas, Ostrea lutaria, and a new species of Ostrea) and one Chilean oyster (Ostrea chilensis) showed that larvae of species other than O. lutaria and O. chilensis share certain features. One conspicuous feature is a distinct tract, termed here the posterior dorsal sulcus, which runs from the posterior margin of prodissoconch I to the valve margin of prodissoconch II; other characteristic features are an umbonate, inequivalve shell and a provinculum bearing distinct teeth. The larvae of O. lutaria and O. chilensis, in contrast, lack the posterior dorsal sulcus, are nonumbonate, and have nearly equal valves with an edentulous provinculum. These distinctive features, together with other adult features, suggest that the two species are more appropriately included in a separate genus. The name Tiostrea is proposed for the new genus. Certain supraspecific groupings within the Ostreinae need to be re‐examined in the light of breeding experiments.     

Breeding,growth, and aestivation of the Canterbury mudfish,Neochanna burrowsius (Salmoniformes: Galaxiidae)

Neochanna burrowsius (Phillipps) breeds in late winter and spring. Eggs are widely scattered, and adhere to leaves, stems, and suspended roots of aquatic and bankside vegetation in the sluggish or still waters of the adult habitat. Fish were successfully bred in ponds and tanks; hatching time for eggs varied greatly under different conditions of light and temperature. Fry are free swimming until they adopt the nocturnal, cryptic habits of adults when 30–50 mm long. Growth in the first year is rapid, sexual maturity being reached at 1 year old; subsequent growth is slow. Aestivation occurred successfully in shaded vegetable detritus or gravel. Holes were sometimes used, but fish did not make their own burrows for aestivation. When dissolved oxygen was low, captive fish left the water if able to do so without leaving     

Morphologic investigation of “uncharted” seamount from central Indian basin revisited with multibeam sonar system

Morphology of a seamount at 12°35'E and 76°18.5’ and two abyssal hills in its vicinity is described using the Hydrosweep multibeam‐swath bathymetric system. The height of the seamount is 1350 m, and it occupies an area of 330 km². Its basal width is 22.5 km, and the mount has a gentle and longer western flank and a steep and shorter eastern flank. There is a characteristic terracelike feature on the western flank, about 300 m from the top. A caldera is also observed on top of the seamount. Slope angles in this area are high (over 35"). Results of morphologic studies of the seamount from the multibeam survey are comparable to those from a narrow‐beam echosounding survey. The origin of the seamount may be related to the presence of a fracture zone at 75°45'E.     

The proposed introduction of the large‐mouth black bass micropterus salmoides (lacepede) into New Zealand

Known characteristics of the largemouth black bass, Micropterus salmoides (Lacépède), in its natural habitats in North America and as an introduction in other areas are discussed in relation to the suggestion that the fish should be introduced into New Zealand. It is concluded that much more research on the New Zealand ecosystems is necessary before a realistic assessment can be made of the likely effects of the predatory bass on indigenous fish and on trout fisheries.     

Dinoflagellates of the genus Dinophysis Ehrenberg from New Zealand coastal waters

Eight marine species of the Dinoflagel‐late genus Dinophysis are recorded from New Zealand coastal waters. Some notes are given on the morphology and range of variation in the New Zealand specimens as seen in the scanning electron microscope.     

Adaptations of the chiton Sypharochiton pelliserpentis to rocky and estuarine habitats

Various morphological and physiological features of Sypharochiton pelliserpentis (Quoy & Gaimard, 1835) were examined in relation to the different physico‐chemical characteristics experienced at 4 sites on Kaikoura Peninsula and 2 sites in the Avon‐Heathcote Estuary. Body water content of chitons from high‐shore exposed and estuarine rocky sites was significantly greater (P<0.005) and desiccation rates were significantly less (P<0.05) than those of chitons from low‐shore marine sites and an estuarine mudflat. The percentage of body water loss causing death was greatest for high‐shore marine chitons and least for estuarine chitons. Estuarine chitons had relatively more gill tissue than marine individuals. Body shape appeared to be correlated with intensity of wave action, and narrow animals were found in more wave‐exposed areas. Variations in radula length showed no clear‐cut trends among localities.     

The distribution and morphology of tintinnids (ciliate protozoans) from the coastal waters around New Zealand

Tintinnids from the surface plankton of New Zealand coastal waters are illustrated with scanning electron micrographs. Brief notes are given on their taxonomy, and their use of silica grains, diatom valves, and coccoliths in construction of the lorica is discussed. Distributional data are given for each species and these are related to the hydrological regime.     

Larval development of Boccardia knoxi,a shell‐infesting spionid polychaete

Larvae of Boccardia knoxi (Rainer) were reared in the laboratory after dissection from brood capsules extracted from the outer shell and perio‐stracum of Cookia sulcata and Haliotis iris collected from Tasman Bay, New Zealand. All the eggs within each brood capsule developed into embryos. The dissected larvae had provisional setae and fed on phytoplankton. Larval development is described through to metamorphosis.