When and how? Freshwater mussel recolonization in Lake Orta

Thanks to a video posted on a social network, live mussels of Unio elongatulus, have been recorded from Lake Orta (Italy) over one century after the last (and only) report. With its long and well documented history of pollution, Lake Orta offers the opportunity to document the post-extirpation recovery of freshwater unionid mussels. This case evidences that recovery/recolonization is possible despite a high devastation in the past, and permits to evaluate how fast recolonization may occur, in which way, and in what conditions. The answer to the \u27how fast\u27 was sought by estimating the age of the larger and seemingly older individuals of the population. To address the \u27in which way\u27 we compared the haplotypes of Lake Orta specimens of Unio elongatulus (the only species present) with those of surrounding populations. We concluded that, since Lake Orta lacks a direct connection with the putative source populations, colonizing mussels were almost certainly transported by fish carrying glochidia that were used for lake restocking after liming. Data from the long-term monitoring of water chemistry and sediments have allowed defining what conditions proved to be suitable for survival making possible the start of mussels recovery. But not only water and sediment quality matters for mussels recovery, which was delayed by nearly ten years after the reappearance of fish. This delay reflects the need of the whole trophic chain to be reestablished to allow the survival of the suitable and healthy host-fish populations necessary for mussels reproduction

TROMBOSE AÓRTICA – UMA MANIFESTAÇÃO SINGULAR DA DOENÇA DE CROHN

Aortic thrombosis (AT) is an unusual extraintestinal manifestation of Crohn’s disease (CD). We present a case of a male submitted to supracondylar amputation of the right lower limb due to irreversible acute ischemia. During the post-operative period, he developed signs of contralateral limb ischemia and performed complementary diagnostic tests which revealed a thrombus in the aortic bifurcation, a terminal ileum thickening, compatible with CD, and a polypoid lesion in the distal rectum. After patient staging and colorectal surgery, the complete resolution of AT was demonstrated.A trombose aórtica (TA) é uma manifestação extraintestinal rara da doença de Crohn (DC). Reporta-se um caso de um doente submetido a amputação supra-condiliana do membro inferior direito por isquémia aguda irreversível. No período pós-operatório desenvolveu sinais de isquémia do membro inferior contralateral, tendo realizado vários exames complementares de diagnóstico que revelaram a presença de um trombo na bifurcação aórtica, um espessamento do íleo terminal, compatível com DC, e uma lesão polipóide no reto distal. Após estadiamento do doente e realização de cirurgia colorretal, verificou-se a resolução completa do TA

The role of adaptive resistance in a widespread freshwater mussel species

Organism features, such as size, weight, sex and age, among others, can influence the success of parasitism. For species that depend on a host to complete their life cycle, such as freshwater mussels (Bivalvia, Unionida), understanding how these traits influence parasitism can help guide management actions aimed at improving their reproductive success, ultimately benefitting their conservation. In this study, the physiological compatibility between the duck mussel Anodonta anatina and its host fish was investigated in a simultaneous infestation experiment on four (three native and one non-native) fish species using sympatric and allopatric host strains. The success of glochidia metamorphosis in juvenile mussels was evaluated as a function of host species, strain and fish length. Successful metamorphosis was achieved in almost all fish species tested and differences were detected between allopatric and sympatric strains, with higher values found in allopatric hosts. Allopatric strains of primary hosts produce more juveniles than marginal hosts and non-native species. In addition, larger fish have lower rates of metamorphosis. The results confirm recent findings showing high variation in the metamorphosis success of A. anatina glochidia among different native and non-native hosts, both in the natural environment and in artificial laboratory infestations. Allopatric hosts were more suitable for encystment, demonstrating potential adaptive immunity, not yet observed in A. anatina. Nevertheless, A. anatina may temporarily exploit the naivety of smaller fish regardless of strain. Overall, the results suggest that mussel propagation, reproduction and reintroduction efforts should consider the mechanisms that influence adaptive immunity in fish, including differences in compatibility within and between populations of sympatric and allopatric host strains. This situation should be taken into account, as successful metamorphosis is an important factor in the selection of hosts for juvenile development, especially in efforts to propagate endangered mussel species.The authors are grateful to Fernando Miranda—Polytechnic University of Bragança for their support in the host samples and daily monitoring of the experiment. This research was supported by Portuguese FCT— Foundation for Science and Technology, Project FRESHCO: Multiple implications of invasive species on freshwater mussel co-extinction processes (contract PTDC/AGR-FOR/1627/2014-04/SAICT/2015) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2019). FCT also supported Manuel Lopes-Lima (2020.03608.CEECIND). Rogério C. Lima dos Santos was supported by doctoral grants from the Programa de Doutorado-Sanduíche no Exterior—Coordenaç˜ao de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001.info:eu-repo/semantics/publishedVersio

Symbolic Computation of Variational Symmetries in Optimal Control

We use a computer algebra system to compute, in an efficient way, optimal control variational symmetries up to a gauge term. The symmetries are then used to obtain families of Noether's first integrals, possibly in the presence of nonconservative external forces. As an application, we obtain eight independent first integrals for the sub-Riemannian nilpotent problem (2,3,5,8).Comment: Presented at the 4th Junior European Meeting on "Control and Optimization", Bialystok Technical University, Bialystok, Poland, 11-14 September 2005. Accepted (24-Feb-2006) to Control & Cybernetic

The role of social networks and citizen science in environmental research: the unexpected revival of freshwater mussels in Lake Orta

Social networks are increasingly used for many conservation and environmental educational purposes. The usefulness for ecological studies is exemplified by the casual discovery of the recovery of freshwater mussels in Lake Orta. Mussels were extirpated by severe industrial pollution soon after 1926 and over the following decades their recovery was prevented by acidification and increase of metal concentrations. Even after the improvement of water conditions obtained by limning, the lack of mussels was taken for granted based on the legacy effects of accumulated toxins in the sediments, and on the limited potential for most extirpated species of mussels to naturally recolonize. The probability of mussel\u27s recovery in Lake Orta was considered poor also for the apparent lack of access to restocking populations, which is essential to start the natural recolonization of an area. Because of the assumption that mussels were absent and of the difficulties of locating mussels their recolonization went unnoticed for about 15 years. Only in 2014 the casual discovery of mussels in Lake Orta was made possible thanks to an amateur video posted on YouTube and delivered to one of us through Facebook: this highlights once more the potential role of social networks for conservation and environmental issues. Freshwater mussels are challenging to locate because they are often rare, spatially clustered, and difficult to detect. The recolonization of Lake Orta went unnoticed probably due to the limited extent of the colonized area, low density and, at least initially, the small size of individuals. In such cases the contribution of citizen science can be crucial to provide the reporting even of small populations present in restricted areas and/or not easily accessible. An extensive search along the lake perimeter is being performed through the volunteer collaboration of local SCUBA divers and an online survey through social networks

Phytoplankton survey of “Barrinha”lagoon (Mira – Portugal)

This work reports a one year survey (October 2008 to October 2009) where limnology and plankton data from Barrinha lagoon (Mira-Portugal - 40° 27′ 22″ N, 8° 48′ 7″ W) were analyzed. This lagoon shows peculiar geochemical features being one of the few places in Portugal where the freshwater bivalve Anodonta cygnea can be found. This study consisted on monthly collections of water samples, with identification and quantification of the planktonic communities found in the water. Physical-chemical parameters of the water were also analyzed (temperature, dissolved oxygen, conductivity, pH, nitrites, nitrates, ammonia) as well as organic and inorganic particles and bacteria in the water. The importance of plankton and of phytoplankton in particular is unquestionable; it is the base of the food chain, source of oxygen and can also be used as bio-indicator of water quality. A total of 75 taxa of plankton were identified in the water samples, being 71 of phytoplankton and 4 of zooplankton. The most abundant taxon was Chlorophyceae with 30 taxa (abundances vary from 25% to 75%), then by Bacillariophyceae with 20 taxa (abundances vary from 10% to 75%), followed by the Cryptophyceae represented dominantly by only one genus the Crypotmonas (abundances vary from 10% to 35%) and Cyanophyceae 10 taxa (which reach up a maximum of 7.5% of total abundances of phytoplankton). Among the zooplankton, that was always very scarce, the Protozoa were the main group found. In term of physical-chemical parameters of the water the data were quite uniform except in the end of summer, in this period the lagoon begins to show some signs of eutrophication: decay of nutrients concentration, organic and inorganic particles, followed by oxygen depletion, which favours a simple algae to growth (Cryptomonas) in detriment of all other species of plankton, that in this period reach its minimums. Escherischia coli, Enterococci and total aerobic mesophilic (TAM) microorganisms were indentified and quantified in the water, their abundances change throughout the year, their occurrence are human correlated and they give a good scenario about the water quality in the habitat

FRESHCO: multiple implications of invasive species on freshwater mussel decline and coextinction processes

Freshwater mussels (FM) are among the most threatened faunistic groups worldwide. FM depend on fish to complete their life cycle, where mussel larvae (glochidia) use a specifíc range offish hosts. This trait makes them particularly threatened by invasive alien species (IAS) since changes on the host físh populations may eventually lead to the decline or co-extinction ofthe dependent species. The Iberian Península holds a high levei ofthreatened freshwater species, including físh and mussels. Furthermore, Iberian freshwater systems are among the most heavily invaded ecosystems in the world. Under those considerations, FRESHCO project aims to estimate the direct and indirect impacts of selected highly IAS belonging to distinct functional groups (from plants to vertebrates) on the native Iberian FM and its fish host fauna. Five tasks (T) will be executed: Tl will use fíeld and lab experiments to assess the possible competition between the IAS C. fl.uminea and native FM; T2 will be composed ofa series oflab experiments to assess host fish suitability of native FM; T3 will use molecular and classical detection tools to analyze the diets ofselected IAS and assess their predation on FM larvae, juveniles and adults; T4 will use a battery offíeld and lab experiments to assess the impact ofmassive annual die-offs ofthe invasive aquatic plant E. crassipes on the native FM; and in T5, 150 sites ofthe Douro river basin will be surveyed where mussel and fish assemblages and their habitats will be characterized, in arder to evaluate and distinguish the impacts of IAS and habitat degradation on the native fauna. From an ecological point of view, expected results from this project would help to elucidate the real impacts ofthe most prominent IAS on the threatened native FM and fish species in Iberia. From a management point ofview, this project will facilitate a more effective allocation ofresources spent on both native species conservation and IAS management.info:eu-repo/semantics/publishedVersio

FRESHCO project – preliminary results assessing the multiple implications of invasive species on freshwater mussel decline and coexistence processes

The Iberian freshwater ecosystems are highly invaded by a myriad of organisms that threaten their native biodiversity, including fish and mussels. FRESHCO project is evaluating the direct and indirect impacts of selected invasive alien species (IAS) belonging to distinct fuinctional groups (from plants to vertebrates) on the native Iberian freshwater mussels (FM) and its fí.sh host fauna. Preliminary results for the designed tasks (T) were obtained: Tl - based on field and lab experiments, FM exhibited lower growth, lower physiological condition, and higher locomotor activity at higher Corbicula fluminea density, suggesting that FM are negatively affected by C. fluminea and may be displaced to less favourable habitats; T2 - only native Iberian fishes are effective hosts for Unio delphinus and Potomida littoralis, while Anodonta anatína hás a more wide range of host fishes that may include non-native species; T3- molecular and classical detection tools hás been used to analyze the diets of selected IAS (Lepomis gibbosus, Pacifastacus leniusculus, Procambarus clarkii, Neovison vison) and preliminary results showed that ali these IAS predate FM; T4 - 150 sampling sites in Douro basin (Portugal and Spain) were surveyed and mussel and fish assemblages and their habitats characterized. In opposition to salmonid streams, which maintain a good ecológica! status, large number of median-sized and lowland rivers display marked changes in abiotic conditions and biotic composition, including a higher proportion of non-native species presence. From an ecological point ofview, overall results would help to clarify the real impacts of the most prominent IAS on the threatened native FM and íish species in Iberia. From a management point ofview, this project will contribute with information that can be used in a more effective conservation of native species and management of IASMultiple implications of invasive species on freshwater mussel decline and coextinction processes" was funded by FCT - Science and Technological National Portuguese Foundation - Project PTDC/AGR-FOR/1627/2014 - 04/SAICT/2015 and by the Project 3599 -Promoting Scientific Production and Technological Development and the Establishment of Thematic Networks 3599-PPCDT supported by FEDER - European Community Fundinfo:eu-repo/semantics/publishedVersio