Temperature and meal size effects on the postprandial metabolism and energetics in a boid snake

We investigated the combined effect of meal size and temperature on the aerobic metabolism and energetics of digestion in Boa constrictor amarali. Oxygen uptake rates ((V) over dot o(2)) and the. duration of the digestion were determined in snakes fed with meals equaling to 5%, 10%, 20%, and 40% of the snake's body mass at 25degrees and 30 degreesC. The maximum (V) over dot o(2) values attained during digestion were greater at 30 degreesC than at 25 degreesC. Both maximal (V) over dot (o2) values and the duration of the specific dynamic action. (SDA) were attained sooner at 30 degreesC than at 25 degreesC. Therefore, the temperature effect on digestion in Boa is characterized by the shortening of the SDA duration at the expense of increased. Energy allocated to SDA was not affected by meal size but. was greater at 25 degreesC compared to 30 degreesC. This indicates that a postprandial thermophilic response can be advantageous not only by decreasing the duration of digestion but also by improving digestive efficiency. Maximal (V) over dot o(2) and SDA duration. increased with meal size at both temperatures.

Magnetostratigraphy of ODP Leg 107 holes

Apart from Site 650, core disturbance due to rotary drilling severely compromised the quality of the magnetostratigraphic data obtained from Leg 107 sediments. The correlation of polarity zones to the geomagnetic polarity time scale cannot be made solely on the basis of pattern fit. The proposed correlations are consistent between sites, and this consistency is constrained by the biostratigraphic datums. The resulting biomagnetostratigraphic correlations are reviewed in the synthesis section of this volume. The purpose of this paper is to document the magnetic stratigraphies, and present the preferred correlation to the geomagnetic reversal time scale. Four implications of the proposed correlations are: (1) The Mio-Pliocene boundary occurs in the lowest reversed interval of the Gilbert (Chron 3r) at about 4.9 Ma. (2) The thick pre-Pliocene lacustrine sequence recovered at Site 652 appears to have been deposited entirely within a single reversed polarity chron (Chron 3r). (3) The balatino-type gypsum recovered at Site 654 was also deposited entirely within this polarity chron (Chron 3r). (4) The Tortonian-Messinian boundary occurs within a normal polarity zone which is probably correlative to Chron 6 (Chron 3B) giving a boundary age of about 6.4 Ma.

(Table 2) Chemical composition of basalts from the DSDP Leg 74 Walvis Ridge transect

Five sites were drilled along a transect of the Walvis Ridge. The basement rocks range in age from 69 to 71 m.y., and the deeper sites are slightly younger, in agreement with the sea-floor-spreading magnetic lineations. Geophysical and petrological evidence indicates that the Walvis Ridge was formed at a mid-ocean ridge at anomalously shallow elevations. The basement complex, associated with the relatively smooth acoustic basement in the area, consists of pillowed basalt and massive flows alternating with nannofossil chalk and limestone that contain a significant volcanogenic component. Basalts are quartz tholeiites at the ridge crest and olivine tholeiites downslope. The sediment sections are dominated by carbonate oozes and chalks with volcanogenic material common in the lower parts of the sediment columns. The volcanogenic sediments probably were derived from sources on the Walvis Ridge. Paleodepth estimates based on the benthic fauna are consistent with a normal crustal-cooling rate of subsidence of the Walvis Ridge. The shoalest site in the transect sank below sea level in the late Paleocene, and benthic fauna suggest a rapid sea-level lowering in the mid-Oligocene. Average accumulation rates during the Cenozoic indicate three peaks in the rate of supply of carbonate to the sea floor, that is, early Pliocene, late middle Miocene, and late Paleocene to early Eocene. Carbonate accumulation rates for the rest of the Cenozoic averaged 1 g/cm**2/kyr. Dissolution had a marked effect on sediment accumulation in the deeper sites, particularly during the late Miocene, Oligocene, and middle to late Eocene. Changes in the rates of accumulation as a function of depth demonstrate that the upper part of the water column had a greater degree of undersaturation with respect to carbonate during times of high productivity. Even when the calcium carbonate compensation depth (CCD) was below 4400 m, a significant amount of carbonate was dissolved at the shallower sites. The flora and fauna of the Walvis Ridge are temperate in nature. Warmer-water faunas are found in the uppermost Maastrichtian and lower Eocene sediments, with cooler-water faunas present in the lower Paleocene, Oligocene, and middle Miocene. The boreal elements of the lower Pliocene are replaced by more temperate forms in the middle Pliocene. The Cretaceous-Tertiary boundary was recovered in four sites drilled, with the sediments containing well-preserved nannofossils but poorly preserved foraminifera.