Environmental forcing of an estuarine gradient of zooplankton abundance and production

Doutoramento em BiologiaOs copépodes são pequenos e frágeis crustáceos que constituem um dos grupos de organismos metazoários mais abundantes do mundo. Em ambientes marinhos e estuarinos, os copépodes assumem um papel de extrema relevância ao nível das cadeias tróficas, nomeadamente na transferência de matéria e energia de níveis tróficos inferiores (fitoplâncton) para níveis tróficos superiores (ex. larvas de peixe). A importância ecológica dos copépodes reflecte-se no elevado número de citações constantes no ISI Web of Knowledge (7716 citações entre 1969 e 2006) e no destaque que os mesmos continuam a possuir em estudos recentes de planctologia marinha e estuarina. Esta dissertação teve como objectivos principais (1) descrever variações espacio-temporais em termos de abundância e biomassa de populações estuarinas de copépodes da Ria de Aveiro (Portugal) e a sua relação com parâmetros hidrológicos (salinidade, temperatura, clorofila a e precipitação; (2) comparar as taxas de crescimento e desenvolvimento de populações alopátricas de copépodes; (3) definir modelos de crescimento dependentes da temperatura para as formas juvenis (nauplius e copepoditos) de Acartia tonsa; (4) avaliar o forçamento ambiental na distribuição e abundância de populações de Acartia e (5) calcular taxas de produção secundária potenciais para as populações de Acartia. Numa primeira fase, foi objecto de estudo a comunidade de copépodes estuarinos, para a qual foram descritos os padrões temporais de abundância e biomassa e obtidas estimativas de produção secundária. Os resultados obtidos neste estudo permitiram concluir que, entre outros aspectos, a abundância e biomassa da comunidade de copépodes da Ria de Aveiro se encontra significativamente correlacionada de modo positivo com a salinidade e com a temperatura da água. As estimativas das taxas de produção secundária derivadas da aplicação de modelos gerais de crescimento mostraram ser algo diferentes, sendo a estimativa dada pelo modelo de Hunthey & Lopez (1992) mais elevada do que a obtida pelo modelo de Hirst & Bunker (2003). O crescimento e desenvolvimento de espécies de Acartia foram estudados sob condições controladas em termos de alimento e temperatura, de forma a serem definidos modelos de crescimento dependentes da temperatura. A partir destes estudos concluiu-se que as populações alopátricas possuem diferentes respostas à temperatura. Além deste aspecto, também se observou que, pelo menos no caso da A.tonsa, as taxas de crescimento das formas juvenis (nauplius e copepoditos) estimadas in situ ou sob condições saturantes de alimento são similares. resumo O forçamento ambiental das populações de Acartia no Canal de Mira foi avaliado através de uma análise de componentes principais (ACP), que permitiu a análise simultânea das alterações espaciais e temporais das diferentes populações. Esta análise identificou três zonas distintas no estuário com base na abundância de Acartia spp.. Para cada zona, análises de correlação com diferentes desfasamentos temporais entre as variáveis ambientais e a abundância de copépodes, permitiram detectar a existência de forçamentos ambientais específicos, assim como um efeito positivo da biomassa fitoplanctónica na abundância do zooplâncton verificada meses mais tarde. Esta tese demonstrou igualmente a grande importância que as populações de Acartia, especialmente a mais abundante – A. tonsa – assumem na transferência de matéria e energia no ambiente planctónico da Ria de Aveiro (Portugal).Copepods are small fragile and tiny crustaceans that form one of the world’s most abundant groups of metazoan organisms. In estuarine and marine environments copepods assume a key role in what trophic chains are concerned, namely in the transfer of matter and energy from lower trophic levels (phytoplankton) to higher trophic levels (ex. fish larvae). Copepods ecological importance is proven by the high number of quotations in ISI Web of Knowledge (7716 quotations between 1969 and 2006) and in the significance that they still have concerning current studies on estuarine and marine planktonic studies. The main goals of the present thesis were (1) to characterize and to describe the spatialtemporal patterns of abundance, biomass and production of the estuarine copepod community from Ria de Aveiro (Portugal) and its relationship with hydrological data (salinity, temperature, chlorophyll a and rainfall regime); (2) to compare growth and developmental rates of allopatric copepod populations; (3) to define temperature dependent growth models for nauplii and copepodites of Acartia tonsa; (4) to evaluate environmental forcing on the distribution and abundance of Acartia populations; and (5) to estimate potential secondary production rates of Acartia populations. In a first stage estuarine copepods community was studied, time patterns of abundance and biomass having been described and estimates of secondary production having been obtained. Results achieved by this study have led us to the conclusion that, among other aspects, abundance and biomass of the copepods community in Ria de Aveiro is positively correlated with water salinity and temperature. Estimates of secondary production rates deriving from the use of general growth models were different, the estimate obtained by Hunthey & Lopez (1992) model being higher than the one resulting from the Hirst & Bunker (2003) one. In order to define specific temperature-dependent copepod growth models, the growth and development of Acartia species were studied under controlled conditions of food and temperature. From those studies it was concluded that allopatric populations have different temperature responses. Additionally, it was also observed that, at least for A.tonsa, the growth rates of nauplii and copepodites at saturated food conditions and in situ conditions of food are similar. Environmental forcing of Acartia populations in Canal de Mira was evaluated by means of 3-mode PCA, which analyses simultaneously spatial and temporal changes of multispecies assemblages. This analysis identified three distinct zones along the estuary based on Acartia spp. abundance. For each zone time-lagged correlations between environmental variables and copepods abundance indicated that different zones were forced by different combinations of variables and the existence of delayed effects of phytoplanktonic biomass on the abundance of A.tonsa. This thesis also demonstrated the high importance that Acartia populations, in particular the most abundant A.tonsa, assume on the transfer of matter and energy in the planktonic realm of Ria de Aveiro (Portugal)

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others

Culturas laboratoriais de Diatomáceas marinhas: perfis de Exopolissacarídeos

Foi objectivo principal deste trabalho a identificação de espécies diatomológicas marinhas produtoras de exopolissacarídeos e a sua caracterização. Para tal, e partindo de amostras de plâncton e de bentos recolhidas no Canal de Navegação da Ria de Aveiro, foram obtidas, após amplificação e isolamento, 19 culturas unialgais. De entre elas, foram escolhidas 6 que sofreram um processo de axenização. Em resultado deste processo, somente se obtiveram culturas axénicas de Navicula directa (W. Smith) Ralfs, Amphora holsatica Hustedt e Melosira nummuloides (Dillwyn) Agardh. Para estes 3 taxa quando cultivados em meio de cultura limitado, foi determinada a respectiva curva de crescimento, e relacionada com a consequente variação da concentração dos nutrientes no meio (NO3-, PO43- e SiO2) ao longo do tempo de cultivo. Para além do modo de crescimento, foram também determinados os padrões de produção de hidratos de carbono celulares e extracelulares elaborados pelos taxa, ao longo do tempo de incubação. Os padrões de produção de hidratos de carbono extracelulares foram posteriormente relacionados com a respectiva curva de crescimento e com a variação da concentração de nutrientes presentes no meio de cultura. Por último, procedeu-se à determinação da composição dos hidratos de carbono extracelulares em termos de açucares simples e conteúdo em ácidos urónicos. Concluiu-se que, os taxa em causa elaboram e exudam quantidades diferentes de hidratos de carbono, que tal exudação ocorre quando a concentração dos nutrientes presentes no meio diminui, e que a máxima produção foi atingida durante a fase estacionária. Através do isolamento e caracterização dos polímeros presentes no meio de cultura de Navicula directa (W. Smith) Ralfs, Amphora holsatica Hustedt e Melosira nummuloides (Dillwyn) Agardh, conclui-se que se tratavam de polissacarídeos (exopolissacarídeos). Estes mostraram ser bastante semelhantes entre si, sendo no geral considerados como um polímero de ácidos urónicos. Poderão existir no entanto certas diferenças em termos de composição em açúcares simples, facto em parte comprovado durante este estudo.The aim of this work was to identify marine diatom species that produce and exudate exopolysaccharides, and also to characterise such polymers. Therefore, plankton and benthos samples were collected in the Canal de Navegação – Ria de Aveiro, and after the amplification and isolation, 19 monospecific algal cultures were obtained. Six of the 19 microalgal cultures maintained in laboratorial conditions, were submitted to an axenic process by the use of an antibiotic solution. Axenic cultures were successfully obtained for Navicula directa (W. Smith) Ralfs, Amphora holsatica Hustedt and Melosira nummuloides (Dillwyn) Agardh. The growth curve of those 3 taxa in batch cultures were then determined and compared with the concentration of nutrients (NO3-, PO43- and SiO2) in the medium, during the experimentation period. The pattern of cellular and extracellular carbohydrate production was also defined in those 3 axenic cultures of marine diatoms. For each culture, the carbohydrate production was compared with the growth curve and with the variation of nutrient concentration in the medium. The analysis of neutral sugars and uronic acids was performed for the exopolysaccharides isolated from the culture media of Navicula directa (W. Smith) Ralfs, Amphora holsatica Hustedt and Melosira nummuloides (Dillwyn) Agardh.It was concluded that the 3 marine diatoms produced and exudated different amounts of carbohydrates, and that the exudation process was more important when the media were almost nutrient-depleted, and also when the species reached the stationary growth phase. The exopolysaccharides produced by the three species, mainly polymers of uronic acids, are very similar. However, the results suggest that certain differences in the composition of neutral sugars may occur.Mestrado em Ciências das Zonas Costeira

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data