Foraminifera in Samples Taken Mainly from Eniwetok Atoll in 1956*

SYNOPSIS. The foraminiferal distribution in samples from the Western Pacific collected in the summer of 1956 is presented, particularly those of the islets comprising Eniwetok Atoll. Some information is based upon samples taken shortly after atomic tests had been conducted. The distribution of foraminifera from northern islets where the tests were conducted is compared with that from the southern islets of Eniwetok Atoll. Collections from Eniwetok Atoll are compared with those made the same summer from other locations in the Southern and Western Pacific. A comparison is also made with the survey made by Cushman et al. of the Marshall Islands prior to bomb testing.     

Effect of Fluctuations in Temperature on the Metabolism of Intertidal Invertebrates

SVNOPSIS. Compensatory changes in the level of activity of intertidalorganisms may occur in response to the thermal conditions whichprevail in the habitat. These involve an increase in the activityof those animals subjected to low temperatures and a correspondingsuppression of activity in those animals subjected to high temperaturesso that organisms with a wide geographical range, or livingover a range of shore levels, have comparable rates of activity.However, the rate of activity varies markedly with short-termfluctuations in temperature, as does the rate of respirationof active animals. Recent evidence suggests that the rate ofrespiration of quiescent animals is relatively independent oftemperature over the normal environmental range, and thus themetabolism is well-suited to an environment where rapid fluctuationsin temperature occur. Further, the extent of the thermal rangeover which metabolism is relatively independent of temperatureis modifiable according to season and storage-temperature. Similarchanges occur in the respiration of cell-free homogenates ofcertain intertidal organisms. Acclimation in such organismsinvolves not only a modification in the level of the activeand standard rates of metabolism but also an alteration in theform of the rate/temperature curve such that the range of temperature-independentmetabolism is appropriate to the thermal conditions prevailingin the habitat.     

A Race for Space? How Sphagnum fuscum stabilizes vegetation composition during long‐term climate manipulations

Strong climate warming is predicted at higher latitudes this century, with potentially major consequences for productivity and carbon sequestration. Although northern peatlands contain one‐third of the world's soil organic carbon, little is known about the long‐term responses to experimental climate change of vascular plant communities in these Sphagnum‐dominated ecosystems. We aimed to see how long‐term experimental climate manipulations, relevant to different predicted future climate scenarios, affect total vascular plant abundance and species composition when the community is dominated by mosses. During 8 years, we investigated how the vascular plant community of a Sphagnum fuscum‐dominated subarctic peat bog responded to six experimental climate regimes, including factorial combinations of summer as well as spring warming and a thicker snow cover. Vascular plant species composition in our peat bog was more stable than is typically observed in (sub)arctic experiments: neither changes in total vascular plant abundance, nor in individual species abundances, Shannon's diversity or evenness were found in response to the climate manipulations. For three key species (Empetrum hermaphroditum, Betula nana and S. fuscum) we also measured whether the treatments had a sustained effect on plant length growth responses and how these responses interacted. Contrasting with the stability at the community level, both key shrubs and the peatmoss showed sustained positive growth responses at the plant level to the climate treatments. However, a higher percentage of moss‐encroached E. hermaphroditum shoots and a lack of change in B. nana net shrub height indicated encroachment by S. fuscum, resulting in long‐term stability of the vascular community composition: in a warmer world, vascular species of subarctic peat bogs appear to just keep pace with growing Sphagnum in their race for space. Our findings contribute to general ecological theory by demonstrating that community resistance to environmental changes does not necessarily mean inertia in vegetation response.