See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/227217309 Holocene Adélie penguin diet in Victoria Land, Antarctica Article in Polar Biology · July 2009 DOI: 10.1007/s00300-009-0607-4 CITATIONS READS 20 176 5 authors, including: Sandra Lorenzini Silvia Olmastroni Università di Pisa Università degli Studi di Siena 9 PUBLICATIONS 74 CITATIONS 35 PUBLICATIONS 709 CITATIONS SEE PROFILE SEE PROFILE Francesco Pezzo Maria Cristina Salvatore Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Ozzano Emili… Università di Pisa 43 PUBLICATIONS 481 CITATIONS 149 PUBLICATIONS 1,107 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Argentina View project PNRA2013 AZ1.22 Conservation of a polar mesopredator species susceptible to ecosystem change. View project All content following this page was uploaded by Carlo Baroni on 17 May 2014. The user has requested enhancement of the downloaded file. Polar Biol DOI 10.1007/s00300-009-0607-4 ORIGINAL PAPER Holocene Ade´lie penguin diet in Victoria Land, Antarctica Sandra Lorenzini Æ Silvia Olmastroni Æ Francesco Pezzo Æ Maria Cristina Salvatore Æ Carlo Baroni Received: 17 November 2008 / Revised: 13 February 2009 / Accepted: 25 February 2009 Ó Springer-Verlag 2009 Abstract Ornithogenic soils (N = 97) dated up to 7000 Possible explanations of the variations of the abundance of Before Present (BP) were sampled in 16 relict and modern the fish prey in the diet are discussed in the context of the breeding colonies of Ade´lie penguin along the Victoria paleoclimatic events and as possible consequences of die- Land coast (Ross Sea, Antarctica). Taxonomic identifica- tary shifts due to the temporal variation of prey availability tion of fish otoliths (N = 677) recovered in these soils in the Ross Sea ecosystem. allowed to identify the Antarctic silverfish as the most eaten prey (90.1%) throughout the investigated period. A Keywords Ade´lie penguin Á Ornithogenic soils Á morphometric analysis of the otoliths revealed that the Prey remains Á Paleodiet Á Victoria Land Ade´lie penguin primarily selected prey averaging 67.23 ± 23 mm of standard length. Temporal distribution of Pleuragramma antarcticum showed a peak between Introduction 2,000 and 4,000 years BP, a period corresponding to the maximum spread of Ade´lie penguin in the Victoria Land. First defined by Syroechkovsky (1959), ornithogenic soils (bird guano-formed) represent the biggest resource of organic matter in both maritime and continental Antarctica. Since their discovery, these soils have represented an S. Lorenzini (&) Á C. Baroni excellent opportunity to study pedogenetic processes (i.e. Dipartimento di Scienze della Terra, soil formation), nutrient cycling and chemistry in very Universita` di Pisa, extreme environmental conditions (Ugolini 1972; Speir Via S. Maria 53, 56126 Pisa, Italy e-mail: [email protected] and Cowling 1984; Heine and Speir 1989; Tatur and Myrcha 1989; Zhu et al. 2005; Barrett et al. 2006; Michel C. Baroni e-mail: [email protected] et al. 2006; Liu et al. 2006; Simas et al. 2007). In conti- nental Antarctica, ornithogenic soils are provided by a S. Olmastroni Á F. Pezzo single animal source: the Ade´lie Penguin (Pygoscelis Dipartimento di Scienze Ambientali ‘‘G. Sarfatti’’, adeliae Hombron and Jacquinot 1841). In a long-term Universita` degli Studi di Siena, Via P. A. Mattioli 4, 53100 Siena, Italy occupied colony, penguin guano seeps through the per- meable pebbly nests and accumulates at their base to form S. Olmastroni e-mail: [email protected] ornithogenic soils. Thanks to the dry and cold Antarctic conditions, ornithogenic soils also preserve a long-dated F. Pezzo e-mail: [email protected] heritage of the Ade´lie penguin community (Spellerberg 1970; Stonehouse 1970; Bochenski 1985; Baroni 1994; M. C. Salvatore Baroni and Orombelli 1994a; Emslie 1995; Emslie et al. Dipartimento di Scienze della Terra, 1998). The extension of the organic layers is a function of Universita` di Roma ‘‘La Sapienza’’, P.le A. Moro 5, 00185 Rome, Italy the size, the age of establishment, and the persistence of the e-mail: [email protected] colony (Baroni 1994). Accurate stratigraphic sections of 123 Polar Biol ornithogenic soils have revealed different guano layers (up conditions inhibited the presence and settling of Ade´lie to five) that record multi-occupational phases of the colo- penguin colonies (Hall et al. 2006). nies (Baroni and Orombelli 1991, 1994a; Baroni and Hall Ornithogenic soils also well preserve hard parts of die- 2004). Radiocarbon-dated penguin remains, such as bones, tary remains, such as fish otoliths, bones, teeth, and squid guano, and eggshell fragments collected from these organic beaks. Calcareous fish otoliths and chitinous squid beaks in soils, provide a multi-millenary record of Ade´lie Penguin particular have demonstrated a strong preservation power. colonization that has been revealed to be particularly Taxonomic identification of such remains allows us to interesting for paleoenvironmental studies (Baroni and define a long-term Ade´lie penguin paleodietary record Orombelli 1991, 1994a;Baroni1994;Emslie2001; Lambert (Emslie et al. 1998; McDaniel and Emslie 2002; Emslie et al. 2002; Emslie et al. 2003; Shepherd et al. 2005; and McDaniel 2002; Polito et al. 2002; Emslie and Hall et al. 2006; Emslie and Patterson 2007; Emslie et al. Woehler 2005). 2007). Ade´lie penguins are sensitive indicators of the Previous paleoecological studies have yielded consi- Antarctic climate and of environmental parameters that derable dietary information on non-krill prey thanks to the regulate their presence and distribution (Ainley 2002). excellent preservation of remains found within ornithogenic Where ornithogenic soils are common features, Ade´lie soils. Concentrated in the area of the Antarctica Peninsula penguins have found encouraging ecological conditions for and in the East Antarctica, these studies have confirmed that their colonization. At these sites, the endurance of these from the mid-Holocene to the present day the Antarctic favorable setting environments is related to the thickness of silverfish (Pleuragramma antarcticum Boulenger 1902) these soils: an enduring occupation of a colony drops a and glacial squid (Psychroteuthis glacialis Thiele 1920) thick layer made from nest pebbles, penguin remains and have been important components in the Ade´lie penguin guano, and the older the colony, the thicker the accumu- diet, being the most common species represented in the lation of guano (Ugolini 1972). In particular, well- sediments (Emslie et al. 1998; Emslie 2001; Emslie and developed sequences of ornithogenic soils testify the McDaniel 2002; McDaniel and Emslie 2002, Emslie and ancient availability of ice-free coastal terrains suitable to Woehler 2005). Furthermore, the proportion of these prey nest and breed. In Victoria Land (Ross Sea), radiocarbon items in the past Ade´lie penguin diet varied in accordance dating of penguin guano, bones, and eggshells collected with climatic cooling and warming trends (cfr. Emslie et al. from these soils together with other datable organic mate- 1998; Emslie and McDaniel 2002). In the Ross Sea Region, rials provides data for reconstructing the retreat of glaciers detailed information on long-term Ade´lie penguin paleodiet in coastal areas after the last Glacial Maximum (&18– composition, prey fluctuations and possible environmental 20,000 years Before Present, BP) and the following emer- implications is lacking, with the exception of the southern sion of coastline during the Holocene period (starting about area. At Ross Island, a 1,000-year record of Ade´lie penguin 8000 BP) (Baroni and Orombelli 1991, 1994b; Baroni and diet indicates P. antarcticum as the most abundant non-krill Hall 2004; Hall et al. 2004). Radiocarbon dates from prey species, although it has been decreasing in importance abandoned penguin colonies scattered on the VL coast over the past 600 years, perhaps in response to the Little Ice (from the northernmost site at Cape Adare to the south- Age cooling period (Polito et al. 2002). The present study ernmost sites at Ross Island) indicate that Ade´lie penguins investigates for the first time an up-to-7000 BP Ade´lie occupied colonies in the Terra Nova Bay region since 7200 penguin non-krill paleodiet record, distributed in an about BP (Baroni and Orombelli 1994a). The occurrence of 600-km-long spatial dataset spanning from Cape Adare ornithogenic soils both in the vicinity of currently occupied (71°180S) to Dunlop Island (77°140S) along the Victoria colonies and in areas no longer colonized by penguins Land Coast, Ross Sea. The extent of the investigated spatial attests that, during the Holocene, the penguin population and temporal context allows us to reconstruct the as yet varied according to changing environmental conditions longest and widest Ade´lie penguin paleodietary record of (Baroni and Orombelli 1994a; Lambert et al. 2002; Polito Victoria Land. et al. 2002). Especially after the period between 4500 and 97 previously 14C-dated penguin guano samples, col- 2500 BP, indicated as a ‘‘penguin optimum’’ by Baroni and lected from several locations, have been analyzed through Orombelli (1994a), abrupt environmental changes caused a taxonomic identification and quantification of recovered drastic abandonment of several colonies and a dramatic fish otoliths. Compared to previous studies, the accurate decrease