Giuseppe Orombelli

Abandoned penguin rookeries as Holocene paleoclimatic indicators in Antarctica

Penguins are sensitive indicators of the Antarctic climate and of the environmental parameters that limit their presence and distribution. Paleoenvironmental data, obtained from the study of abandoned penguin rookeries ( Pygoscelis adeliae ) along the Victoria Land coast in Antarctica, indicate 14C date of 11-13 ka for the oldest abandoned rookery and supply new information about the timing of glacier retreat in southern Victoria Land after the last glacial maximum. The continuous presence of the Adelie penguins is documented from 7 ka. According to our data, the limiting factors that control the presence of penguins along the coast of Victoria Land changed during the Holocene. Whereas several colonies were occupied for very long periods, other sites were used for more or less extended periods and then abandoned. The greatest diffusion of rookeries occurred between 3 and 4 ka, a period of particularly favorable environmental conditions that has never been repeated. It was followed by a sudden decrease in the number of penguin rookeries shortly after 3 ka. This event has been attributed to an increase of the sea-ice extension and may have been correlated to a worldwide phase of climate change near the Subboreal-Subatlantic boundary. A minor phase of penguin reoccupation occurred locally in the eighth to fourteenth centuries (A.D.). Because the presence and number of penguins reflect the state of health of the Antarctic marine ecosystem, it is important to evaluate the variations in their distribution in the past, in the absence of human-induced changes.

Holocene raised beaches at Terra Nova Bay, Victoria Land, Antarctica

Abstract More than 40 14C dates for raised beaches at Terra Nova Bay ranging from the present to 7505 ± 230 yr B.P. supply minimum or maximum limiting ages that bracket a relative sea-level curve for this part of Victoria Land. Most samples consist of guano and penguin remains collected from abandoned nesting sites on beach deposits. Up to four 14C dates in stratigraphic sequence have been obtained in two soil profiles. Other samples consist of marine shells collected both within and on the surface of raised beaches. All 14C ages for organisms that lived or fed in circumantarctic waters were corrected for a large reservoir effect. The calibrated ages delimit a first relative sea-level curve for Victoria Land. Rates of uplift ranged from about 10 mm/yr following deglaciation to about 2 mm/yr in the last 3 millennia. Widespread presence of Adelie penguin nesting sites suggests that Terra Nova Bay was deglaciated before 7065 ± 250 yr B.P. ( 7059 6439 cal yr B.P.), when environmental conditions in the coastal area were similar to the present ones.

Glacier contraction during the middle Holocene in the western Italian Alps: Evidence and implications

Radiocarbon dates of peat from the top and base of a bog exposed by recent retreat of Rutor Glacier show that the glacier front terminated upvalley from the bog from 8400 until at least 6000 B.P. The evidence is consistent with botanical data that point to a high tree line during the interval and to reconstructed mean July temperatures at least 4 °C warmer than present temperatures. If the mass-balance history of the glacier is typical of other glaciers in this region, it is likely that average equilibrium-line altitudes during the interval of contraction remained above those of the present and well above those of subsequent neoglacial ice advances.

Holocene glacier variations in the Terra Nova Bay area (Victoria Land, Antarctica)

Information on Holocene glacier variations in Antarctica is limited and sometimes contradictory. However, if the behaviour of the glaciers during the recent past can be clarified, their sensitivity to climatic changes can be evaluated and their contribution to the sea level variation may be predicted. Through the study of local glaciers and floating ice shelves in the Terra Nova Bay area, new information has been gathered. Between 7500 and 5000 yr B.P., after the glacial retreat which followed the Last Glacial Maximum, the Nansen Ice Sheet and the Hells Gate ice shelf were a few kilometres less extensive than they are now. During the second half of the Holocene, both the local glaciers and the ice shelves advanced to positions that were more extensive than their present ones, although not all the variations are adequately dated. A retreat phase of the Edmonson Point glacier occurred during late Middle Ages between 920–1050 A.D. and 1270–1400 A.D. as documented by ten 14 C dates obtained from shells in ice-cored moraines. A subsequent advance occurred after the 15th century in a period corresponding to the Little Ice Age .

Limited Pliocene/Pleistocene glaciation in Deep Freeze Range, northern Victoria Land, Antarctica, derived from in situ cosmogenic nuclides

The question of how stable the climate in Antarctica has been during the last few million years compared to the rest of the planet is still controversial. This study attempts to add new information to the discussion by reconstructing the timing and spatial extent of glacial advances in northern Victoria Land over tens of thousands to millions of years. In Terra Nova Bay region, surface exposure ages and erosion rates of glacially rounded bedrock and glacial erratics have been determined using the cosmogenic nuclides 3He, 10Be and 21Ne. Three morphological units have been analysed. They yield minimum ages of 11 to 34 ka, 309 ka, and 2.6 Ma, respectively. Erosion rates were as low as 20 cm Ma−1 since middle Pliocene time. Taking erosion into account, the oldest surface is 5.3 Ma old. Pleistocene glacier advances had considerable extent, reaching up to 780 m above modern ice levels, but have been restricted to the valleys since at least mid-Pliocene. The existence of landscapes of mid-Pliocene age in northern Victoria Land implies that the climatic stability of the McMurdo Dry Valleys is not unique within the Transantarctic Mountains, but rather the expression of a constantly cold and hyperarid climate regime in entire Victoria Land.

LICHEN GROWTH CURVES FOR THE SOUTHERN FLANK OF THE MONT BLANC MASSIF, WESTERN ITALIAN ALPS

Growth curves spanning the last two and a half centuries have been constructed for Rhizocarpon geographicum s.l. and Aspicilia cinerea, two ubiquitous lichen species that grow on granitic substrate...

Sustainable management of the Mediterranean

The Mediterranean Sea is both a biodiversity and a political crossroad. Three continents are flanking each other along its shores, with an unparalleled mixture of cultures, economies, religions and political regimes. What human culture divides, however, is joined by ecology. The national boundaries mean nothing, for Nature. The use of the marine space must first of all respond to ecological laws, and these have logical supremacy over economic and political laws. Managing the Mediterranean Sea is one of the most challenging enterprises humans can attempt. The range of disciplines involved is so cross-cutting that the specialists at the extremes of the range often cannot understand each other, due to the complex jargons they use. This volume contains a selection of papers presented at the conference ‘‘Sustainable management of the Mediterranean’’, held in Rome at the Accademia Nazionale dei Lincei on March 21st for the XIV World Water Day 2014. It aims at sketching a conceptual landscape covering many aspects that are crucial for the integrity of the Mediterranean Sea. There is marine ecology, of course, but it is linked to inland ecology, due to the influence of rivers in a semi-closed basin as the Mediterranean one. Microbial communities are reviewed too, because they are changing just as the rest of the biota, and their changes might have great, albeit not immediately perceived, impacts on the functioning of Mediterranean Ecosystems. The Suez Canal connects the Indian with the Atlantic Ocean, enhancing shipping activities in the basin. The regulations of the impacts of these ships are constantly evolving and are worth being considered and revised. Overfishing is a plague for Mediterranean biota, but fisheries are an important portion of Mediterranean culture and must be managed so as to allow fishermen to continue to fish without destroying the resource they rely upon. Fisheries provide proteins to a growing population that, especially in the Mediterranean area, does have ample margins of improvement in its own diet(s). The overexploited populations might be restocked with specific programs, and the first attempts in this direction are taking place. Water circulation connects the various parts of the Mediterranean, transporting propagules (i.e. the propagation phases in the life cycle of all species) throughout the basin. Moreover, the enhanced frequency of extreme events, such as intense storms, is adding further complexity to an already complex landscape. The title of this volume, the fil rouge that connects all its chapters, is the application of a widely employed jargon: F. Boero Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Universita del Salento, 73100 Lecce, Italy e-mail: boero@unisalento.it