Search

Unidad de excelencia María de Maeztu CEX2019-000940-M

A multiproxy approach was applied to a sediment core retrieved from the deep crater Lake Funda, located in the middle of the North Atlantic Ocean on Flores Island, Azores archipelago (Portugal). The purpose of this study was to determine how this ecosystem responded to natural and anthropogenic forces over the last millennium. We distinguished three main phases in lake evolution using multiproxy reconstructions and documentary sources. (A) Climate and lake catchment processes, as well as internal ones, were the main drivers of ecosystem variability before 1335 CE, when human disturbances were absent in the Lake Funda catchment. (B) The second phase is marked by unprecedented changes in all studied proxies between 1335 and 1560 CE, including abrupt changes in the composition and diversity of diatom and chironomid assemblages. Synergistic effects from high climate variability and the onset of human disturbances in the catchment (e.g., introduction of livestock) during the Medieval Climate Anomaly-Little Ice Age transition, led to an increase in lake trophic state from mesotrophic to eutrophic conditions. (C) In the last phase (1560 CE to the present), the eutrophic conditions in Lake Funda were maintained through a positive feedback loop between lake productivity and in-lake phosphorous recycling. Variability within the lake ecosystem was mainly associated with climate variability and internal lake dynamics (e.g., phosphorus remobilization). Our results show that a paleoecological approach is crucial to understanding lake ecological states in the present-day in order to develop locally adapted management and restoration strategies. A long-term perspective enables us to understand the harmful consequences of ongoing climate change and human disturbances on lake ecosystems

Islands are among the last regions on Earth settled and transformed by human activities, and they provide replicated model systems for analysis of how people affect ecological functions. By analyzing 27 representative fossil pollen sequences encompassing the past 5000 years from islands globally, we quantified the rates of vegetation compositional change before and after human arrival. After human arrival, rates of turnover accelerate by a median factor of 11, with faster rates on islands colonized in the past 1500 years than for those colonized earlier. This global anthropogenic acceleration in turnover suggests that islands are on trajectories of continuing change. Strategies for biodiversity conservation and ecosystem restoration must acknowledge the long duration of human impacts and the degree to which ecological changes today differ from prehuman dynamics.

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos (Coua). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios (87Sr/86Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar.

Previous studies on lacustrine sedimentary sequences in the Azores show that climate variability and vulcanism along with the arrival of humans played a signi#12;cant role in the recent development of these insular Azorean ecosystems. However, the timing and rate of anthropogenic impacts on these lakes is poorly constrained. Paleoecological research allows us to reconstruct ecological conditions prior to and after human settlement, thereby contributing to our understanding of how species and island ecosystems responded to both natural and anthropogenic disturbances. To assess both types of impacts over the last 1000 years, we analysed the elemental geochemistry on bulk organic matter, diatoms, and chironomid remains in a 994 cm-long sediment core recovered from Lake Funda (Flores Island, Azores) in 2017. Preliminary results from Lake Funda show that human colonization was the main driver of ecological changes. We identi#12;ed three major ecological phases: (1) 950-1350 yr AD, a pristine lake ecosystem with mesotrophic diatom taxa, including benthic and tychoplanktonic life-forms, and free-living chironomids species representing an undisturbed environment; 2) 1350-1450 yr AD, the release of cattle and gradual forest clearance lead to an increase in nutrient inputs and the start of the human-impacted phase; and, (3) after Portuguese settlement, from 1450 yr AD to present, a second human-impacted phase resulted in lake eutrophication and the development of an anoxic hypolimnion due to an increase of nutrient loading. The #12;rst anthropogenic phase resulted in a drastic 50% decline of the overall biodiversity with a shift to planktonic diatom species and free-living chironomids, while the second was characterised by a substantial reduction in the density of chironomids and diatom assemblage shifts towards the dominance of Aulacoseira granulata and A. ambigua suggesting a shift in lake trophy. Other external drivers like major climate oscillations likely play a role wit

The discovery and colonization of islands by humans has invariably resulted in their widespread ecological transformation. The small and isolated populations of many island taxa, and their evolution in the absence of humans and their introduced taxa, mean that they are particularly vulnerable to human activities. Consequently, even the most degraded islands are a focus for restoration, eradication, and monitoring programmes to protect the remaining endemic and/or relict populations. Here, we build a framework that incorporates an assessment of the degree of change from multiple baseline reference periods using long-term ecological data. The use of multiple reference points may provide information on both the variability of natural systems and responses to successive waves of cultural transformation of island ecosystems, involving, for example, the alteration of fire and grazing regimes and the introduction of non-native species. We provide exemplification of how such approaches can provide valuable information for biodiversity conservation managers of island ecosystems.

Aims: The 50th anniversary of the publication of the seminal book, The Theory of Island Biogeography, by Robert H. MacArthur and Edward O. Wilson, is a timely moment to review and identify key research foci that could advance island biology. Here, we take a collaborative horizon-scanning approach to identify 50 fundamental questions for the continued development of the field. Location: Worldwide. Methods: We adapted a well-established methodology of horizon scanning to identify priority research questions in island biology, and initiated it during the Island Biology 2016 conference held in the Azores. A multidisciplinary working group prepared an initial pool of 187 questions. A series of online surveys was then used to refine a list of the 50 top priority questions. The final shortlist was restricted to questions with a broad conceptual scope, and which should be answerable through achievable research approaches. Results: Questions were structured around four broad and partially overlapping island topics, including: (Macro)Ecology and Biogeography, (Macro)Evolution, Community Ecology, and Conservation and Management. These topics were then subdivided according to the following subject areas: global diversity patterns (five questions in total); island ontogeny and past climate change (4); island rules and syndromes (3); island biogeography theory (4); immigration–speciation–extinction dynamics (5); speciation and diversification (4); dispersal and colonization (3); community assembly (6); biotic interactions (2); global change (5); conservation and management policies (5); and invasive alien species (4). Main conclusions: Collectively, this cross-disciplinary set of topics covering the 50 fundamental questions has the potential to stimulate and guide future research in island biology. By covering fields ranging from biogeography, community ecology and evolution to global change, this horizon scan may help to foster the formation of interdisciplinary research netw

Raposeiro, P. M., Hernández, A., Pla-Rabes, S., Gonçalves, V., Bao, R., Sáez, A., . . . Giralt, S. (2021). Climate change facilitated the early colonization of the Azores Archipelago during medieval times. In Proceedings of the National Academy of Sciences (article e2108236118). US National Academy of Sciences. https://doi.org/10.1073/pnas.2108236118

Raposeiro, P. M., Hernández, A., Pla-Rabes, S., Gonçalves, V., Bao, R., Sáez, A., . . . Giralt, S. (2022). Reply to Elias et al.: Multiproxy evidence of widespread landscape disturbance in multiple Azorean lakes before the Portuguese arrival. Proceedings of the National Academy of Sciences, 119(4), article e2120107119. https://doi.org/10.1073/pnas.2120107119

Fire was rare on Mauritius prior to human arrival (AD 1598); subsequently three phases of elevated fire activity occurred: ca 1630–1747, 1787–1833, and 1950–modern. Elevated fire frequency coincided with periods of high human impact evidenced from the historical record, and is linked to the extinction of island endemics.

Fire was rare on Mauritius prior to human arrival (AD 1598); subsequently three phases of elevated fire activity occurred: ca 1630–1747, 1787–1833, and 1950–modern. Elevated fire frequency coincided with periods of high human impact evidenced from the historical record, and is linked to the extinction of island endemics.

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos (Coua). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios (87Sr/86Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar.