Hypersaline Lagoons from Chile, the Southern Edge of the World

Hypersaline lagoons distributed in arid and semiarid regions are unique ecosystems with unique value stemming from their extremophile biodiversity, limnological properties and services, like mining and waterbird habitat. They are natural laboratories to understand how life evolved in extreme environments and how simple ecosystems function to provide waterbird habitat, an essential noneconomic service. Policymakers need this knowledge to protect these ecosystems increasingly affected by climatic change and human-driven perturbations. Hypersaline lagoons from contrasting latitudinal conditions in Chile provide a study case to evaluate how such conditions affect their microscopic and macroscopic diversities. Those in the hyperarid Atacama Desert in northern Chile are an integral part of mineral-rich salars, whereas Patagonian lagoons are unique among freshwater lakes of glacier origin. Despite latitudinal differences, prokaryotic diversity tends to be similar in both extremes. However, genetically distant brine shrimp (Artemia) species, A. franciscana (north) and A. persimilis (Patagonia), inhabit them. This crustacean is a keystone taxon in the food web, and its abundance indicates ecosystem quality and attracts waterbirds. This chapter stresses the need to systematically monitoring Artemia abundance and all factors affecting its fitness (gut microbiota, parasites, environmental conditions). Finally, the need to conserve these unique and extreme ecosystems is highlighted

Parasitismo por cestodos en Artemia spp. y su implicación en la invasión biológica de Artemia franciscana en la región Mediterránea

La presente Tesis Doctoral trata del fenómeno del parasitismo en el crustáceo Artemia y la implicación de los cestodos en el proceso de invasión biológica de la especie americana Artemia franciscana Kellogg, 1906 en la región Mediterránea. El crustáceo Artemia (Branchiopoda, Anostraca) es el invertebrado más conspicuo de los ecosistemas acuáticos hipersalinos de todo el mundo y un valioso recurso trófico para las poblaciones de aves acuáticas que residen en dichos ecosistemas. El uso generalizado de la especie americana A. franciscana en la acuicultura y acuariofilia han provocado su introducción y expansión fuera de su área nativa, localizándose en la actualidad en todos los continentes y siendo reconocida como una especie acuática invasora a nivel global. En la región del Mediterráneo Occidental, esta especie ha eliminado a muchas poblaciones nativas de Artemia salina y Artemia parthenogenetica y ha invadido humedales de gran importancia como sitios Ramsar y zonas de especial protección para las aves (ZEPA), lo que ha originado un grave problema de conservación. Artemia, además de servir como fuente de alimento para las aves, desempeña un papel esencial para los parásitos intestinales de éstas al actuar como hospedador intermediario en el ciclo biológico de helmintos, principalmente, de la clase Cestoda orden Cyclophyllidea. Esta Tesis consiste en un estudio parasitológico en las especies de Artemia bajo el contexto de una invasión biológica, con un enfoque taxonómico y ecológico, y tratando aspectos relacionados con las interacciones parásito-hospedador en el sistema Cestodos-Artemia-Aves. Los objetivos principales de esta Tesis son: 1) Evaluar el papel de los estados tempranos del desarrollo de A. parthenogenetica (diploide) en la circulación de cestodos de aves acuáticas, 2) Estudiar los factores intrínsecos y extrínsecos que influyen sobre los patrones de infección, 3) Determinar la composición de la comunidad de helmintos parásitos en A. franciscana en origen y describir sus dinámicas espacio-temporales de infección. Comparar estos aspectos con los hallados en las poblaciones introducidas en la Cuenca Mediterránea, 4) Estudiar el papel de la especie exótica A. franciscana como hospedador de los parásitos nativos de las especies de Artemia del Paleártico en un ecosistema invadido, 5) Comparar las interacciones parásito-hospedador entre cestodos nativos y las distintas especies de Artemia en la región Mediterránea, y su implicación en la competencia congenérica, especialmente entre el hospedador exótico A. franciscana y la especie bisexual nativa A. salina. Nuestro trabajo se basó en el examen de las infecciones naturales por cestodos en poblaciones de Artemia del litoral mediterráneo español: A. parthenogenetica (Laguna de La Mata, Alicante), A. salina y A. franciscana-introducida (salinas del Delta del Ebro, Tarragona); así como en la población nativa A. franciscana de Great Salt Lake (Utah, EEUU). Determinamos las comunidades de cestodos y cuantificamos los niveles de infección en las distintas especies de Artemia, evaluamos las variaciones temporales de las infecciones y los efectos de los parásitos sobre el color y la reproducción del hospedador intermediario. Además se exploró la influencia del estado de desarrollo y el sexo de Artemia, la diversidad de hospedadores intermediarios en el caso de poblaciones en coexistencia (nativa-invasora), así como la abundancia y distribución de las aves hospedadores finales sobre los patrones de infección. El estudio sobre la helmintofauna de A. franciscana en Great Salt Lake nos ha permitido aportar los primeros datos sobre el papel de esta especie como hospedador intermediario de sus parásitos naturales y poder comprender mejor su papel como hospedador exótico en el rango mediterráneo invadido. Los resultados de este estudio muestran que A. franciscana en su área nativa participa en el ciclo biológico de, al menos, cinco especies de helmintos pertenecientes a dos grupos: nematodos de la familia Acuariidae y cestodos de las familias Hymenolepididae (Confluaria podicipina, Hymenolepis sensu lato californicus y Wardium sp.) y Dilepididae (Furhmannolepis averini). Para esta última especie este hallazgo supone su primer registro en el Neártico. Se trata de parásitos de zampullines, gaviotas y aves limícolas. Esta población de A. franciscana presenta una mayor prevalencia, intensidad y abundancia total de cestodos comparada con las poblaciones de esta misma especie introducidas en la región Mediterránea. Esto sugiere que la especie exótica A. franciscana está sometida a una menor regulación por los parásitos en los ecosistemas invadidos, lo que explicaría, al menos en parte, su crecimiento demográfico en el área mediterránea donde se ha convertido en una especie invasora. En los diferentes estudios realizados observamos una correspondencia entre la composición de especies de cestodos en el hospedador intermediario Artemia y la comunidad de aves que sirven de hospedadores definitivos y, en general, de su abundancia y distribución en el ecosistema. Con respecto a la influencia de determinados factores en las infecciones, nuestros resultados indican que el estado de desarrollo de Artemia influye en los patrones de su infección por cestodos. En general, se observaron unas tasas de infección más altas en los adultos, lo que sugiere que existe un efecto acumulativo de los parásitos con la edad en el hospedador intermediario. Por otro lado, se observó una infección específica diferencial entre los estadíos tempranos de Artemia y los adultos, lo que parece estar fuertemente relacionado con la estrategia trófica (filtradora o visual) de las aves hospedadores finales. Los metanauplios y juveniles de Artemia son eficientes hospedadores intermediarios en el ciclo de vida de cestodos como Flamingolepis liguloides y F. flamingo, parásitos de aves filtradoras como los flamencos. Nuestros resultados revelan que A. franciscana acumula nuevos parásitos tras su introducción. De hecho, la especie invasora que habita en las salinas del delta del Ebro presenta una amplia diversidad de especies de cestodos comparada con la hallada en otras áreas invadidas, o en su rango nativo. Se registraron 10 especies: Flamingolepis liguloides, Flamingolepis flamingo, Wardium stellorae, Branchiopodataenia gvozdevi y Fimbriarioides tadornae (familia Hymenolepididae); Eurycestus avoceti, Anomotaenia tringae y Anomotaenia microphallos (familia Dilepididae); Gynandrotaenia stammeri y Gynandrotaenia sp. (familia Progynotaeniidae), destacando W. stellorae (parásito de gaviotas) por ser su primer registro conocido en A. franciscana. Observamos diferencias en la tasa de infección y en la distribución de las especies de cestodos entre los individuos juveniles y los adultos, lo que sugiere un efecto de la edad y una posible relación con la estrategia alimenticia del hospedador final. Para este hospedador exótico E. avoceti (parásito de aves limícolas) y F. liguloides (parásito de flamencos) son los cestodos más prevalentes y abundantes en adultos y juveniles, respectivamente. Comparado con su rango nativo (EEUU), los bajos niveles de infección registrados en esta población introducida sugiere que A. franciscana presenta una menor susceptibilidad a los parásitos de las especies nativas de Artemia del Paleártico, siendo muy evidente para el caso de los cestodos de flamencos (como F. liguloides), lo que puede responder a la ausencia de coevolución entre parásitos y hospedadores. Las bajas tasas de infección detectadas en este hospedador exótico pueden comprometer la viabilidad de las poblaciones de algunos de los parásitos. La infección por cestodos causa coloración roja y castración en A. salina y A. franciscana, sin embargo ambos efectos fueron menos notables en el hospedador exótico. Los bajos niveles de infección y la menor castración y coloración roja se traducen en una menor regulación y manipulación por parte de los parásitos y, probablemente, en una menor predación por las aves, lo que puede contribuir al éxito invasor de A. franciscana en el rango mediterráneo invadido. La gran cantidad de muestras analizadas nos permitieron establecer una asociación entre efecto-parásito, principalmente en el caso del hospedador exótico. Pudimos detectar efectos de color para los cestodos de flamencos (F. liguloides, F. flamingo y G. stammeri) y de aves limícolas (E. avoceti, A. tringae y A. microphallos), y efectos de castración para F. liguloides y E. avoceti, aportando las primeras evidencias de la capacidad castradora de los cestodos dilepídidos en Artemia. Los resultados de esta tesis resaltan el papel fundamental de Artemia como hospedador intermediario de helmintos parásitos de aves acuáticas, tanto A. salina y A. parthenogenetica (diploide) en el Paleártico como A. franciscana en el Neártico, y contribuyen a ampliar el conocimiento del parasitismo en Artemia spp., aportando los primeros datos en América. Por otro lado, esta Tesis Doctoral aporta información relevante desde un punto de vista conservacionista. Considerando la importancia de Artemia en la red trófica de los humedales hipersalinos, el conocimiento aportado sobre la capacidad invasora de este crustáceo americano en condiciones naturales y la implicación de los cestodos en su éxito invasor, resulta importante para vislumbrar las consecuencias de la invasión biológica por la especie A. franciscana. En resumen, esta Tesis nos ha permitido contribuir al conocimiento de las interacciones parásito-hospedador bajo el contexto de las invasiones biológicas acuáticas y, en concreto, entender mejor el proceso invasor de A. franciscana en la región Mediterránea. La invasión de esta especie no sólo ha provocado la pérdida de biodiversidad de sus congéneres nativos, sino que los impactos pueden extenderse a la biota nativa global de los ecosistemas hipersalinos, afectando a distintos niveles de interacciones bióticas: parásito-hospedador y predador-presa. Las graves consecuencias de la invasión por esta especie americana ponen en evidencia la necesidad de establecer medidas urgentes de control y manejo para evitar su expansión. Por otro lado, esta tesis propone un nuevo modelo de estudio a considerar dentro del ámbito parasitológico.The aim of this Doctoral Thesis is to study parasitism in the crustacean Artemia and cestodes implication in the biological invasion process of the American species Artemia franciscana Kellogg, 1906 in the Mediterranean region. Artemia is the most conspicuous invertebrate in the aquatic hypersaline ecosystems throughout the world, and an important food source for aquatic birds. The use of the American species A. franciscana in aquaculture and pet industries has resulted in their introductions into ecosystems outside of their native range. Consequently, A. franciscana has invaded many hypersaline wetlands all over the world, and it has been recognized as an aquatic global invasive species. In the Western Mediterranean area, this brine shrimp species has become a threat for the native biodiversity (A. salina and A. parthenogenetica), and it has invaded important wetlands as Ramsar sites and Special Protection Areas for birds, provoking a serious conservation problem. Also, Artemia has an essential role for helminth parasites of aquatic birds, mainly cestode cyclophyllidean. This research is a parasitological study in the context of an invasion, with a taxonomical and ecological perspective, and considering aspects related to host-parasite interactions in the Cestodes-Artemia-Birds system. Our work is based in the natural infections by cestodes in Artemia populations from the Mediterranean coast of Spain: A. parthenogenetica (La Mata lagoon, Alicante), A. salina and A. franciscana-introduced (Ebro Delta salterns, Tarragona); and the native A. franciscana population from Great Salt Lake (Utah, USA). We determined the cestode communities and quantified infection levels in the Artemia spp., evaluated the temporal variations of the infections and parasite effects on Artemia colour and reproductive activity. In addition, we explored the influence of several factors as developmental stage, sex and diversity of intermediate host, as well as abundance and distribution of bird final hosts, on the infection patterns. The study on the helminth infections in A. franciscana in Great Salt Lake allowed us to provide the first data of the role of this species as intermediate host for its natural parasites and to compare with the invaded Mediterranean area. Results of this study shown that A. franciscana participates in the life cycle of, at least, five helminth parasites. Four of them are cestodes: three hymenolepidids i.e. Confluaria podicipina (adult parasitic in grebes), Hymenolepis sensu lato californicus (adult parasitic in gulls), Wardium sp. (definitive host unknown, probably charadriiforms birds), and one dilepidid, Furhmannolepis averini (adult parasitic in phalaropes). For the last species, this is the first record in the Nearctic. In addition, an unidentified nematode of the family Acuariidae was recorded. The overall cestode infection in this native population of A. franciscana in Great Salt Lake is much higher than in the introduced populations of the same host in the Palaearctic region. This result is in agreement with the hypothesis that A. franciscana has a lower susceptibility to the Palaearctic cestode parasites than to cestode parasites in its native range. It suggests that the American brine shrimp is lower regulated by parasites, explaining (at least partially) its higher demographic growth in invaded habitats where it become an invasive species. The species composition of helminth parasites and the spatial variations in their prevalence and abundance may reflect the abundance and distribution of aquatic birds serving as definitive hosts. Concerning the influence of certain factors in the infections, our results indicate that age (in terms of developmental stage) of the intermediate host determines patterns of infection. We found cestode cysticercoids in all developmental stages of brine shrimps except in nauplii. In general, overall infection rates are higher in adults than in metanauplii and juvenile individuals, suggesting an accumulative effect of parasites with advancing host development. In fact, we demonstrated that earlier developmental stages of Artemia have an important role for the circulation of certain parasites species, particularly flamingo parasites (Flamingolepis liguloides and Flamingolepis flamingo). This is probably associated with the feeding behaviour of definitive hosts (filtering versus picking predators), and, also, with the size of parasite eggs and the filtering ability of brine shrimps. Our results demonstrate that A. franciscana has accumulated novel parasites following its introduction. In fact, the invasive species A. franciscana inhabiting the Ebro Delta salterns is characterized by a more diverse assemblage than those observed in other areas of the introduced or native range. We recorded ten cestode species: Flamingolepis liguloides, Flamingolepis flamingo, Wardium stellorae, Branchiopodataenia gvozdevi, Fimbriarioides tadornae (Hymenolepididae); Eurycestus avoceti, Anomotaenia tringae, Anomotaenia microphallos (Dilepididae); Gynandrotaenia stammeri, Gynandrotaenia sp. (Progynotaeniidae). This is also the first record for W. stellorae (a cestode specific of gulls) in this alien brine shrimp. We found a differential infection rate and distribution of cestode species between age groups, suggesting age effect and a relation with final host feeding behaviour. For this exotic host, E. avoceti (parasite of shorebirds) and F. flamingo (flamingo parasite) were the most prevalent and abundant cestodes in adult and juveniles, respectively. Comparing with native range (USA), overall rate of cestode infection in this exotic brine shrimp was much lower. The lower burden of parasites in introduced host suggests A. franciscana is resistant to several native cestode species (such as F. liguloides). Also, when comparing cestode infections between native A. salina and invader A. franciscana from syntopic populations, we found that native host had consistently higher infection parameters, largely because the dominant cestode in A. salina (F. liguloides) was much rarer in A. franciscana. The abundance of E. avoceti and F. liguloides was higher in the A. franciscana population coexisting with A. salina species than when alone, possible because native shrimp provides a better reservoir for parasite circulation. Infection by cestodes caused red colouration and castration in A. salina and A. franciscana, however both these effects were significantly stronger in the native host. The reduced levels of infection and reduced castration effects in A. franciscana suggest that cestodes may not be able to infect or manipulate the alien host to a sufficient extent to ensure viability of parasite populations. The reduced redness suggests that cestode are less likely to reach final hosts (through bird predation) when infecting alien Artemia. The lower regulation and manipulation by parasites likely help A. franciscana outcompete native Artemia species. Resistance to cestodes could be explaining its invasiveness in the Ebro Delta salterns and other invaded ecosystems across the Old World. The results of this Doctoral Thesis highlight the essential role of Artemia as intermediate host for helminth parasites of aquatic birds, A. salina and A. parthenogenetica in the Palaearctic as well A. franciscana in the Nearctic, and contribute to better knowledge of parasitism in Artemia spp., providing first data in America. In other hand, we provide significant information under a conservationist point of view. Considering the importance of Artemia in the trophic web of hypersaline wetlands, the provided knowledge on the invasiveness of this American crustacean in natural conditions and the implications of cestodes in the successful invasion, shed light on the ecological consequences of this biological invasion. In summary, this Thesis allowed us to provide knowledge of host-parasite interactions in the context of the aquatic invasions, in particular, to understand the invasion process of A. franciscana in the Mediterranean region. The invasion of this alien brine shrimp has provoked a biodiversity loss of the genus Artemia, but its impacts may extend to native biota of aquatic hypersaline ecosystems, affecting different levels of biotic interactions: host-parasite and prey-predator. Dramatic consequences of this biological invasion reveal the need to establish urgent measures of control and management to avoid the A. franciscana expansion. In other hand, this Thesis proposes a new study model to be considered in parasitological field

Aquatic pollution may favor the success of the invasive species A. franciscana

The genus Artemia consists of several bisexual and parthenogenetic sibling species. One of them, A. franciscana, originally restricted to the New World, becomes invasive when introduced into ecosystems out of its natural range of distribution. Invasiveness is anthropically favored by the use of cryptobiotic eggs in the aquaculture and pet trade. The mechanisms of out-competition of the autochthonous Artemia by the invader are still poorly understood. Ecological fitness may play a pivotal role, but other underlying biotic and abiotic factors may contribute. Since the presence of toxicants in hypersaline aquatic ecosystems has been documented, our aim here is to study the potential role of an organophosphate pesticide, chlorpyrifos, in a congeneric mechanism of competition between the bisexual A. franciscana (AF), and one of the Old World parthenogenetic siblings, A. parthenogenetica (PD). For this purpose we carried out life table experiments with both species, under different concentrations of the toxicant (0.1, 1 and 5. μg/l), and analyzed the cholinesterase inhibition at different developmental stages. The results evidence that both, AF and PD, showed an elevated tolerance to high ranges of chlorpyrifos, but AF survived better and its fecundity was less affected by the exposure to the pesticide than that of PD. The higher fecundity of AF is a selective advantage in colonization processes leading to its establishment as NIS. Besides, under the potential selective pressure of abiotic factors, such as the presence of toxicants, its higher resistance in terms of survival and biological fitness also indicates out-competitive advantages. © 2015This research was supported by the Spanish Ministry for Science and Innovation projects (CGL2005-02306 and CGL2008-04737-E) “Biodiversidad de Artemia (Branchiopoda, Anostraca) en el Mediterráneo Occidental, archipiélagos Balear y Canario. Efectos de A. franciscana como especie invasora. Implicaciones ecológicas y de interés en acuicultura” y “Biodiversidad amenazada en salinas mediterráneas”. S. Redón was supported by a Ph.D grant (FPI) from the Spanish Ministry of Science and Innovation. D. Guinot was supported by BANCAJA contract.Peer Reviewe

Comparing cestode infections and their consequences for host fitness in two sexual branchiopods: alien Artemia franciscana and native A. salina from syntopic-populations

The American brine shrimp Artemia franciscana is invasive in the Mediterranean region where it has displaced native species (the sexual A. salina, and the clonal A. parthenogenetica) from many salt pond complexes. Artemia populations are parasitized by numerous avian cestodes whose effects have been studied in native species.We present a study from the Ebro Delta salterns (NE Spain), in a salt pond where both A. franciscana and native A. salina populations coexist, providing a unique opportunity to compare the parasite loads of the two sexual species in syntopy. The native species had consistently higher infection parameters, largely because the dominant cestode in A. salina adults and juveniles (Flamingolepis liguloides) was much rarer in A. franciscana. The most abundant cestodes in the alien species were Eurycestus avoceti (in adults) and Flamingolepis flamingo (in juveniles). The abundance of E. avoceti and F. liguloides was higher in the A. franciscana population syntopic with A. salina than in a population sampled at the same time in another pond where the native brine shrimp was absent, possibly because the native shrimp provides a better reservoir for parasite circulation. Infection by cestodes caused red colouration in adult and juvenile A. salina, and also led to castration in a high proportion of adult females. Both these effects were significantly stronger in the native host than in A. franciscana with the same parasite loads. However, for the first time, significant castration effects (for E. avoceti and F. liguloides) and colour change (for six cestode species) were observed in infected A. franciscana. Avian cestodes are likely to help A. franciscana outcompete native species. At the same time, they are likely to reduce the production of A. franciscana cysts in areas where they are harvested commercially.Peer reviewe

Influence of developmental stage and sex on infection of the American brine shrimp Artemia franciscana Kellogg, 1906 by avian cestodes in Ebro Delta salterns, Spain

The American brine shrimp Artemia franciscana Kellogg, 1906 is invasive in the Mediterranean region where it has displaced native populations of sexual A. salina and clonal A. parthenogenetica from many hypersaline wetlands. Brine shrimps are intermediate hosts of several cyclophyllidean avian cestodes, whose effects have been studied in native Artemia. However, determinants of these infections in the alien invader remain unknown. We present the most detailed study to date of parasitism of A. franciscana by cestodes in its invasive range, conducted in the Ebro Delta salterns (NE Spain) over a 33 month period, when a total of 9,293 A. franciscana adults and 8,902 juveniles were studied. We examined for first time whether host age and sex influence infection rates. Ten cestode species were recorded, with a total prevalence of 11.1% in adults and 2.7% in juveniles. The most abundant cestodes were Eurycestus avoceti (in adults) and Flamingolepis flamingo (in juveniles). Prevalence, abundance and intensity of infection were significantly higher in adults for four cestode species (Flamingolepis liguloides, Wardium stellorae, E. avoceti and Anomotaenia microphallos), and significantly higher in juveniles for F. flamingo. Mean cestode species richness was four times higher in adults. One cestode species (F. liguloides), was significantly more abundant in adult females than in adult males. Host age influences infection patterns which seem to be strongly related to the feeding behaviour of avian final hosts (filtering versus picking), suggesting complex ecological interactions among predators, prey and their parasites, with important implications for native biodiversity and ecosystem stability.Peer reviewe

Widespread invasion of American brine shrimp in Mediterranean salt ponds - Enemy release versus Enemy protection

Trabajo presentado en la Annual Meeting British Ecological Society, celebrada en Liverpool del 11 al 14 de diciembre de 2016.The invasion of the American brine shrimpArtemia franciscanais causing a dramatic loss ofArtemiabiodiversity in salt ponds across the lberian Península and the rest of the Mediterranean. In coastal salinas across most of Portugal. Andalusia. Cataluña and France it has excluded the native species (the sexuaiA. salinaand the clonaiA. parthenogenetica) since 1980. Greater efficiency when fi lter-feeding phytoplankton seems to partly explain how the alien outcompetes the native taxa so quickly. Native shrimps are also intennediate hosts for 15 species of avian cestodes, and "enemy release" aids the alien, which has low rates of cestode infection. Dominant cestode species modify the life-history and behaviour of native shrimps ín a manner that changes their functional role within the ecosystem. lnfection induces a switch from benthic to surface feeding with a diet switch that changes isotopic signatures. lnfected shrimps are castrated but accumulate carotenoids and more haemoglobin, and their red coloration attracts final hosts such as na mingos, grebes and shorebirds. Owing to the combination of host castration. increased predation risk and reduced filtering rates, cestodes reduce the capacity of native shrimps te control phytoplankton density in the field, as indicated by chlorophyll concentration. On the other hand, a study from the highly contaminated Tinto and Odie! estuary shows that cestodes provide a paradoxical benefit to native shrimps by increasing their toleran ce to Arsenic and heavy metals. Cestode infection has much less impact on shrimp ecology in the alien speciesA. franciscana, and cestode species differ greatly in their capacity to infect the alien host. We discuss the implications of the invasion for the carrying capacity of waterbirds owing to changes in foraging success.Peer reviewe

A revision of Artemia biodiversity in Macaronesia

Abstract In a biogeographical context, the term Macaronesia broadly embraces the North Atlantic archipelagos of the Azores, Madeira, Selvagens, the Canary Islands, and Cape Verde. The peculiar arid climatic conditions in some of these places have led to the development of marine salt exploitations, which can be counted among the hypersaline habitats of the brine shrimp Artemia (Branchiopoda, Anostraca). Parthenogenetic populations of this anostracan were described in the Canary Islands during the last decades of the 20th century, while the American Artemia franciscana species was recently found in the Cape Verde archipelago. Following an invasive pattern, this exotic species has recently reached the Canary Islands, too. This paper reports information dealing with biotope loss (solar saltworks) in this biogeographical region, together with possible consequences concerning the arrival of invasive species, two factors that frequently promote dramatic biodiversity losses. The discussion of this threat focuses mainly on the Canary Islands archipelago where native species of Artemia still exist.This work was supported by the Spanish National Plan I+D+I projects CGL2008-03277 and CGL2008-04737-E. S.R and M.M were supported by Ph D grants from the Spanish Ministerio de Ciencia e Innovación and the Spanish Consejo Superior de Investigaciones Científicas (CSIC), respectively.Peer Reviewe

Phylogenetic Relationships of Avian Cestodes from Brine Shrimp and Congruence with Larval Morphology

Determining molecular markers for parasites provides a useful tool for their identification, particularly for larval stages with few distinguishable diagnostic characters. Avian cestodes play a key role in the food webs and biodiversity of hypersaline wetlands, yet they remain understudied. Using naturally infected Artemia, we identified cestode larvae (cysticercoids), assessed their genetic diversity, and explored phylogenetic relationships in relation to larval morphology and waterbird final hosts. We obtained partial 18S rDNA sequences for 60 cysticercoids of the family Hymenolepidae infecting Artemia spp. from seven localities and three countries (Spain, the USA, and Chile). We present the first DNA sequences for six taxa: Confluaria podicipina, Fimbriarioides sp., Flamingolepis liguloides, Flamingolepis sp. 1, Flamingolepis sp. 2, and Hymenolepis californicus. Intraspecific sequence variation (0.00–0.19% diversity) was lower than intergroup genetic distance (0.7–14.75%). Phylogenetic analysis revealed three main clades: 1—Flamingolepis, 2—Fimbriarioides, 3—Confluaria and Hymenolepis, all of which separated from hymenolepidids from mammals and terrestrial birds. This clear separation among taxa is congruent with previous morphological identification, validating the 18S gene as a useful marker to discriminate at generic/species level. Working with intermediate hosts allows the expansion of knowledge of taxonomic and genetic diversity of cestodes in wildlife, as well as elucidation of their life cycles.Comisión Nacional de Investigación Científica y Tecnológica 3170939Ministerio de Economia, Industria y Competitividad CGL2016-76067-PMinisterio de Ciencia e Innovación CGL2005-02306, FJC2021-046991-

Participation of metanauplii and juvenile individuals of Artemia parthenogenetica (Branchiopoda) in the circulation of avian cestodes

Adult crustaceans of the genus Artemia (brine shrimps) are intermediate hosts in the life cycle of cestode species parasitic in aquatic birds as their definitive hosts. However, there are no data on the role of larval and juvenile brine shrimps in the transmission of avian helminth parasites. In order to examine the possible role of early developmental stages (nauplii, metanauplii and juveniles) of Artemia for the circulation of avian cestodes, the natural cestode infection in the population of Artemia parthenogenetica from La Mata Lagoon, Mediterranean coast of Spain, was studied. Metacestodes (cysticercoids) of four cestode species were recorded in adult brine shrimps: Flamingolepis liguloides and Flamingolepis flamingo (hymenolepidids parasitic in flamingos), Confluaria podicipina (a hymenolepidid species parasitic in grebes) and Eurycestus avoceti (a dilepidid species parasitic in avocets, stilts, plovers and, to a lesser extent, in flamingos). No cysticercoids were found in nauplii. Two species, F. liguloides and F. flamingo, were found in metanauplii and juvenile brine shrimps. Only 36.3% of the cysticercoids of F. liguloides occurred in adult brine shrimps; the remaining 63.7% were parasitic in metanauplii (39.6%) and juveniles (24.1%). Similarly, the metacestodes of F. flamingo were also distributed among various age groups: in adults (44.4% of cysticercoids), juveniles (27.8%) and metanauplii (27.8%). These results indicate that the early developmental stages of Artemia have an important role for the circulation of certain parasite species. No cysticercoids of C. podicipina and E. avoceti were recorded in larval and juvenile brine shrimps. The selective infestation of larval brine shrimps with flamingo parasites is probably associated with the feeding behaviour of definitive hosts, which are filtering predators; in contrast, grebes and waders pick brine shrimps individually one by one. The possible underlying mechanism for selective infestation of metanauplii and adults by certain cestode species is associated with the size of parasite eggs, allowing only cestode species with small eggs to be ingested by larval brine shrimps.This work was financed by the Spanish National Plan R & D (project CGL-2005- 02306/BOS) and by the EC-funded project WETLANET to the Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences. The first author is supported by a Ph.D. grant (FPI) from the Spanish Ministry of Science and Innovation.Peer reviewe

Explaining Variation in Abundance and Species Diversity of Avian Cestodes in Brine Shrimps in the Salar de Atacama and Other Chilean Wetlands

Further biogeographical studies of parasites are vital to improve our understanding of biodiversity distribution and predict the impacts of global change. Hypersaline lakes are good laboratories to investigate the avian cestode abundance and species diversity given the abundance of hosts (waterbirds and Artemia) and their broad latitudinal distribution. We analysed cestode infection in brine shrimp Artemia franciscana in northern (Atacama) and central Chile and compared them to results from A. persimilis in southern Chile (Patagonia). Thus, we covered a broad latitudinal gradient from 23° to 53° S. Five cestode taxa including two species of the genus Flamingolepis, Gynandrotaenia stammeri, Eurycestus avoceti, and Fuhrmannolepis averini were recorded from A. franciscana in Atacama lagoons (prevalence = 4.1%). In contrast, no cestode infection was detected in central Chile, likely because they are temporary wetlands. Parasites of flamingos and shorebirds were associated with Atacama lagoons (arid and higher salinity), while Confluaria podicipina and Fimbriarioides sp. (parasites of grebes and ducks, respectively) were dominant in Patagonian lagoons (sub-antarctic and of lower salinity). These differences mirror changes in the relative abundance of the respective final hosts. The flamingo parasite Flamingolepis sp. 1 was the most prevalent and abundant cestode in Atacama, where it was recorded only in autumn. Seasonality and habitat effects (especially abundance and phenology of different bird species) appear to override any latitudinal trends in the prevalence, diversity, and distribution of cestodes. Cestode prevalence was higher in larger wetlands but was not related to the sex of either intermediate host. We recorded a greater taxonomic richness at the cestode family level in Atacama, but a greater dominance of a single family of avian hosts (the flamingos). Ours is the first spatio–temporal study of Artemia cestodes at local and regional scales in the southern hemisphere.Fondo Nacional de Desarrollo Científico y Tecnológico 3170939Ministerio de Ciencia e Innovación CGL2016-76067-