Browsing by Author "Amorim, Katherine"
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- Gelificação dos oceanos – e a culpa não é da alforrecaPublication . Morais, Pedro; Amorim, Katherine; Dias, Ester; Cruz, Joana; Barbosa, Ana; Teodosio, MariaOcean jellification is associated with increasing occurrence of jellyfishes. Jellyfish are gelatinous organisms, with a life cycle composed by sessile stage (polyp) and free living stage (medusa). Blooms jellies, which may have negative impact on fisheries and tourism, are strongly driven by the availability of food, since predators are relatively reduce. The diet of jellies includes small crustacean, egg and fish larvae. Yet, recent UAlg studies showed a much more diverse diet (ex: drifting microbes, terrestrial detritus). Major contributors for ocean jellification are closed connect to men activities and include: (1) excessive input of nutrients (ex: sewage agriculture fertilizers), (2) overfishing of fishes and sea turtles; (3) introduction of artificial structures and (4) changes in hydrological cycle (ex: river dams).
- On the presence of the Ponto-Caspian hydrozoan Cordylophora caspia (Pallas, 1771) in an Iberian estuary: highlights on the introduction vectors and invasion routesPublication . Seyer, Thomas; Morais, Pedro; Amorim, Katherine; Leitão, Francisco; Martins, Flavio; Teodosio, MariaSeveral non-native invertebrate and vertebrate species have been detected in the Guadiana Estuary (SW-Iberian Peninsula, Europe) during the 21st century. In June 2015, the non-native hydroid Cordylophora caspia (Pallas, 1771) was detected for the first time in this estuary, which motivated an assessment of its distribution during late Spring and Summer 2016. The main goals of this paper were to: i) report the presence of Cordylophora caspia and its distribution in the Guadiana Estuary, ii) record the substrates colonized, salinity, and water temperatures at locations where the species was detected, iii) evaluate possible introduction vectors and invasion routes; and iv) discuss the potential impacts and management options. Cordylophora caspia occupied a 25-km stretch of the estuary with salinities between 0.2 and 13.8 and occupied a variety of human-made substrates. Shipping was the most likely introduction vector of C. caspia, which might have originated from populations in the Atlantic Ocean or the Mediterranean Sea. Currently, the potential ecological impacts are likely low since the population size is small due to an apparent shortage of suitable habitat. Economic effects are minimal at present because there are no major industries along the basin extracting water from the estuary. An integrated ecohydrological approach-i.e. freshets released from dams to control the populations of Cnidaria-was proposed to minimize or mitigate the potential negative effects of this species in the Guadiana Estuary.
- The effect of freshwater pulse on Aurelia aurita (Linnaeus 1758) (Cnidaria: Scyphozoa): an ecohydrological solution for controlling jellyfish bloomsPublication . Amorim, Katherine; Teodósio, Maria AlexandraJellyfish blooms are increasingly being reported in coastal areas and have been related to both climate changes and anthropogenic impacts. However, several questions underlying such blooms remain understudied, particularly during their benthic phase (polyps). Salinity is one of the environmental variables that has been linked with blooms occurrence. Reports in Guadiana estuary have correlated high precipitation and high freshwater input to low medusa occurrence. Therefore, we hypothesize that using freshwater pulses from a hydrotechnical structure (Dam) could be a promising ecohydrological approach for controlling jellyfish blooms. To explore this idea, the present study aimed to assess different short term salinity concentrations effects on benthic stages and ephyrae larvae of Aurelia aurita. It also explored the feeding ecology of such stages. It had two set of experiment designs. The first set of experiments focuses on responses of scyphistomae (Experiment I, II ) and ephyrae larvae (Experiment III) under low salinity treatments (3,10,17 and 35(control)). The analyzed variables were survival, asexual reproduction and ecophysiological response (feeding rate and number of swimming pulses). It was found significant difference on scyphistomae survival between control and salinity 3 treatment (p-value < 0,05); on budding reproduction, number of scyphistoma actively budding and feeding response between control and salinity 10; on ephyrae survival between control and salinities 3 and 10 ; and ephyrae swimming pulses between control and salinity 17. It did not present significant difference on the number of strobilating scyphistoma and produced medusa. The second set of experiments investigated diet and feeding strategy of scyphistomae (Experiment IV) and ephyrae (Experiment V). It was used Costello plot method. The present study concluded that short term freshwater pulse may control jellyfish blooms by affecting jellyfish early phases survival, their ecophysiological response, and scyphistomae budding reproduction. It was also concluded that ephyrae and scyphistomae feeding strategy are generalists.