Evidence of early settlement of the Azores archipelago using a high-resolution paleolimnological approach
XX Congress of the Iberian Association of Limnology (AIL-2020), Online Congress 26-29 October Mur... more XX Congress of the Iberian Association of Limnology (AIL-2020), Online Congress 26-29 October Murcia (Spain)is generally attributed to the Portuguese during the XVth century, but recent insights have raised questions about whether the islands were discovered earlier. Paleolimnological data from São Miguel suggest that the island was settled 150 years before the official Portuguese arrival date. To pinpoint the date of first human arrival in the archipelago, we performed multiproxy characterizations (e.g. pollen, diatoms, chironomids, XRF geochemistry, faecal related organic compound) using long continuous sequences of natural lacustrine sedimentary archives to reconstruct past environmental changes for the last millennium across four of the nine islands of the Azores archipelago. We have found evidence of livestock introduction (incl. spores of coprophilous fungi, sterols), extractive forestry, and cereal cultivation around 1150 CE in two islands of the archipelago. After this first human impact period an extensive deforestation and the largescale introduction of exotic species have reshaped the lake and island ecosystems and sedimentary dynamics to present-day status. Hence, our results suggest that the human impact in the Azores archipelago started approximately three centuries prior to the official occupation of the archipelago
Cyanobacteria are among the most diverse morphological microorganisms that inhabit a great variet... more Cyanobacteria are among the most diverse morphological microorganisms that inhabit a great variety of habitats. Their presence in the Azores, a volcanic archipelago of nine islands in the middle of the North Atlantic Ocean, has already been reported. However, due to the high diversity of cyanobacteria habitats, their biodiversity is still understudied, mainly in extreme environments. To address this, a total of 156 cyanobacteria strains from Azores lakes, streams, thermal and terrestrial habitats were isolated. Identification was made based on a polyphasic approach using classical taxonomy (morphological characteristics and environmental data) and phylogeny among 81 strains assessed by maximum likelihood and Bayesian analysis of 16S rDNA partial sequences. The 156 isolates showed a high genera diversity (38) belonging to the orders Chroococcales, Nostocales, Oscillatoriales, and Synechococcales. Eleven new genera for the Azores habitats are here reported, reinforcing that cyanobacte...
Freshwater communities on remote oceanic islands can be depauperate due to the influence of bioge... more Freshwater communities on remote oceanic islands can be depauperate due to the influence of biogeographic processes that operate over a range of spatial scales, influencing the colonization of organisms, and events that shape local freshwater assemblages. The consequences of this paucity in organism diversity for the functioning of these ecosystems are, however, not well understood. Here, we examine the relative decomposition rate of leaf litter of native vs. exotic origin by aquatic macroinvertebrates and microbial communities in an isolated and depauperate oceanic environment. Bags containing a standard amount of leaf litter of each of 10 tree species (5 native and 5 non-native species) were deployed on two streams. Two types of bags differing in mesh size were used to allow or prevent the access of leaf litter to macroinvertebrates, respectively. Over a period of 28 days, mass loss of leaf litter was similar in the two bag types suggesting that macroinvertebrates had little influence on the break down of leaf litter in this system. In addition, there was no difference in mass loss of leaf litter of native and exotic origin. Decomposition rates were highly species-specific suggesting that decomposition rates were related to inhibitory substance specific of each leaf species. Our results add to the wider literature by showing that in depauperate and isolated ecosystems, and in contrast to temperate continental ecosystems, decomposition of plant litter by aquatic macroinvertebrates is negligible.
O presente trabalho surge no âmbito da XIV Expedição Científica a Santa Maria/2009, do Departamen... more O presente trabalho surge no âmbito da XIV Expedição Científica a Santa Maria/2009, do Departamento de Biologia da Universidade dos Açores. Durante esta expedição foram amostrados habitats cavernícolas de duas grutas litorais da Ilha de Santa Maria: Furna Velha (ou das Pombas) e Gruta de Santana (ou dos Anjos). As amostragens consistiram, maioritariamente, em amostras de biofilmes nos locais em que estes foram detectados a olho nu. Amostras complementares de água, sedimentos e material encrostante foram recolhidas em algumas áreas. O estudo realizado insere-se no objectivo geral de caracterização da biodiversidade microbiana troglóbia do arquipélago, em particular, neste trabalho, das comunidades microbianas associadas às grutas resultantes da erosão marinha da ilha mais antiga dos Açores.
RESUMO O presente trabalho surge no âmbito da Expedição Científica do Departamento de Biologia da... more RESUMO O presente trabalho surge no âmbito da Expedição Científica do Departamento de Biologia da Universidade dos Açores à ilha de Santa Maria, durante a qual foram amostrados diversos ambientes aquáticos para o estudo da sua biodiversidade. O trabalho realizado possibilitou a actualização da lista de espécies de Chironomidae para a ilha de Santa Maria, tendo sido encontrados quatro novos registos para esta ilha.
A list of the terrestrial and marine biota from the Azores
The Azores is a remote oceanic archipelago of nine islands which belongs to the Macaronesia bioge... more The Azores is a remote oceanic archipelago of nine islands which belongs to the Macaronesia biogeographical region and is among the richest regions concerning fungi, plant and animal diversity in Europe. This checklist lists all the species of the most important terrestrial and marine taxonomic groups. The total number of terrestrial and marine taxa (species and subspecies) in the Azores is estimated in about 8047. The marine organisms currently listed make up about 23% of the Azorean biodiversity. The total number of terrestrial and marine endemic taxa (species and subspecies) in the Azores is estimated of about 491.
Fish introduction may have marked effects on the trophic dynamics and ecological state of former ... more Fish introduction may have marked effects on the trophic dynamics and ecological state of former fishless lakes, but due to scarcity of historical data this can seldom be documented. We used remains of cladoceran, chironomid and pigment assemblages in the sediment archive to unravel the effect of introduction of carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss) and a cyprinid (Chondrostoma oligolepis) in Lake Fogo, the Azores (Portugal). The stratigraphical record showed two major shifts in community assemblage coinciding with the time of introduction of carp (AD ca. 1890) and trout (AD 1941), respectively. Carp introduction was followed by an abrupt and major decline in the abundance of chironomids, a shift in the cladoceran community from a benthic to a more pelagic dominated community, and Daphnia size was significantly reduced. Pigment assemblages also indicated a shift from a benthic to a pelagic dominated ecosystem, as cryptophytes became markedly more abundant at the expense of benthic diatoms. Trout introduction was followed by a return to a more benthic cladoceran and benthic algae (pigments) dominated state, which we attribute to trout predation on carp leading to improved water clarity. A steady increase in the abundance of pigments and cladoceran remains followed, suggesting enhanced productivity, which may be attributed to enhanced atmospheric nitrogen deposition and introduction of C. oligolepis. We conclude that fish introduction has profoundly altered the trophic dynamics and the relative importance of benthic and pelagic production in this species poor and natural fishless lake in the Azores, and likely in most others lakes at the
Lake ecosystems are nowadays often subjected to multi-stressors, such as eutrophication, climate ... more Lake ecosystems are nowadays often subjected to multi-stressors, such as eutrophication, climate change, and fish manipulations, the effects of which can be difficult to disentangle, not least from the usual short-term limnological time-series that are available. However, multi-proxy paleoecological approaches may offer such opportunities, especially in the study of remote island lakes characterized by being species poor and buffered somewhat against the recent climate change. We
Subfossil biotic assemblages in surface sediments of lakes have been used to infer ecological con... more Subfossil biotic assemblages in surface sediments of lakes have been used to infer ecological conditions across environmental gradients.. Local variables are usually the major drives of assemblage composition, but in remote oceanic islands biogeographic filters may play a significant role. To assess the contribution of local and regional filters in the composition of subfossil diatoms and chironomid assemblages in surface sediments forty-one lakes in Azores archipelago ()were studied and related to environmental variables. Ordination techniques were used to identify the drivers that best explain the composition of these assemblages. Both assemblages are influenced by multiple limnological variables (conductivity, pH, nutrients). However, diatom assemblages differed mainly in the proportion of planktonic versus benthic species along the lakes' depth gradient while Chironomids differed significantly between islands but not between lake depths.. Thus, biogeographic filters play an important role in shaping islands freshwater communities, particularly insect ones, more influenced by geographic variables. Results demonstrate the accuracy and potential of biotic remains in sediments for applied studies of lake ecology, trophic status, climatic trends and ecological reconstruction and evolution of lakes. In the Azores, the application of this information in the development of inference models, is envisaged as further step to accomplish these goals.
We investigate the macroecological patterns of the terrestrial biota of the Azorean archipelago, ... more We investigate the macroecological patterns of the terrestrial biota of the Azorean archipelago, namely the species-range size distributions, the distance decay of similarity, and the island species-area relationship (ISAR). We use the most recent up-to-date checklists to describe the diversity at the island level for nine groups (Lichens, Fungi, Diatoms, Bryophytes, Vascular Plants, Nematodes, Molluscs, Arthropods, Vertebrates). The particularities of the Azorean biota result in some differences to the patterns commonly found in other oceanic archipelagos. Strikingly, bryophytes, molluscs and vertebrates show a bimodal species-range size distribution, and vascular plants a right unimodal distribution due the high numbers of widespread species. Such high compositional homogeneity between islands also results in non-significant or even negative decays of similarity with distance among islands for most groups. Dispersal ability, together with other particular characteristics of each taxon, also shapes these distributions, as well as the relationships between island species richness, and area and time. Strikingly, the degree of departure of the richness of the whole archipelago from the SAR of its constituent islands largely depends on the dispersal ability of each group. Comparative studies with other oceanic archipelagos of the globe are however needed to understand the biogeographical and evolutionary processes shaping the remarkably low diversity of the Azorean biota.
The identification of higher scale geographical processes (e.g., island location) that shape regi... more The identification of higher scale geographical processes (e.g., island location) that shape regional (catchment and landscape patterns) and local factors (e.g., water quality, microhabitat) is crucial to a correct understanding of diatom distribution, especially in isolated oceanic islands'. To assess the contribution of these processes in the composition of diatom assemblages in insular permanent streams, a total of 316 samples were studied from 37 sites along 14 permanent streams in Azores archipelago and related to environmental variables. Ordination techniques were used to identify the forcing factors that best explain the composition of diatom assemblages. The results revealed how individual and collective patterns emerging from local, regional, and geographic factors, and their shared variance, provided us with more detailed insight into what factors determine the structure of insular diatom assemblages in Azorean streams. The variance explained by local factors (24.3%) dominated over the regional (20.9%) and geographic fractions (18.5%). This result supports the notion that insular stream ecosystems and their communities are under strong abiotic control, as well as their continental counterparts. The results of this study provide support for current and future stream ecosystem research and baseline information for developing integrated freshwater management strategies for streams on the Azorean archipelago.
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