Marisa Fernandes-de-Castilho’s research while affiliated with Federal University of Paraná and other places

In this study, we evaluated the capacity of the Biotic Ligand Model (BLM) to predict copper toxicity in white-waters of the Solimões-Amazon River. LC50 tests using the species Otocinclus vittatus (Regan, 1904) were performed with Solimões-Amazon river water (100%) at 20%, 40%, 60%, and 80% dilutions. A sevenfold decrease in both dissolved and total Cu toxicity was observed in the experiment conducted with 100% when compared to 20% white-water, indicating that physicochemical characteristics of white-water attenuate Cu toxicity. There was agreement between the observed LC50 and the LC50 predicted by the BLM after the adjustment of critical accumulation concentration (LA50) for O. vittatus. BLM modeling indicated that dissolved organic carbon (DOC) and pH were the most important water parameters influencing Cu toxicity, followed by Ca(2+). Our results highlight the first evidence that the BLM presents potential to predict Cu toxicity to aquatic organisms in the white-water of the Solimões-Amazon River.

Os ácidos biliares são potentes estimulantes olfatórios e gustatórios em peixes. Registros em eletro-olfactograma foram usados para testar se o epitélio olfatório de Pseudoplatystoma corruscans, pintado, é sensível aos ácidos biliares, alguns dos quais têm sido propostos como feromônios. Foram selecionados cinco de uma lista de trinta ácidos biliares previamente testados em atividade olfatória em peixes. Testes de adaptação cruzada demonstraram que a sensibilidade aos ácidos biliares se dá por 3 classes independentes de sites de receptores olfatórios. O ácido taurocólico (TCA) e o ácido tauroquenodesoxicólico (TCD) foram os compostos mais potentes. Em testes de evasão/preferência, P. corruscans prefere água contendo o ácido TCA. Os ácidos biliares são discriminadas por epitélio olfatório de pintado, evidenciando que estes compostos podem funcionar como feromônios.

Chemical communication is widely used in aquatic environments, where visual or auditory signals may not be always effective. Fish of the superorder Ostariophysi are known to display epidermal cells (club cells) that produce and store alarm substances, which are released to the water when the skin is damaged. Responses to alarm substances range widely, between active searches for refuge to a complete stop in any locomotor activity. In this study a large number of binucleated club cells (average density of 11 cells /mu m(2)) were histologically observed in the skin of the catfish Rhamdia quelen (known as jundia). Skin extract (2, 5, and 10% w/v) applied for 15 minutes to conspecifics elicited increase in swimming activity and in the area visited by the fish inside the tank. However, exposure to the epithelial alarm cue did not evoke any stress response: plasma osmolality, ions (sodium, chloride, magnesium, and potassium), glucose and cortisol remained unchanged. In conclusion, the conspecific alarm cue of the jundia induces behavioral responses but not an acute stress response upon short-term exposure, compatible with its role in fostering physical integrity without representing major stress activation. Considering that in the natural environment such stimuli must quickly disappear due to dilution and that rapid protection responses may be necessary upon the possibility of an approaching predator, a faster mechanism to assure survival may come into play, such as sympathetic nervous system activation.

Después de una breve retrospectiva histórica de la ciencia del bienestar animal, en este artículo reconocemos la capacidad de sentir en animales no-humanos; pero enfatizamos que un problema crucial aun persiste al definir y medir el bienestar animal. Desalentamos el uso de medidas fisiológicas para evaluar el bienestar. Argumentamos que hay bases teóricas suficientes para tales patrones en el caso del estrés, pero no en el caso del bienestar, porque en este caso la vida puede no estar en riesgo. En contrapartida, defendemos un abordaje basado en la preferencia o escogencia de los animales, la cual está basada en la decisión del animal. Por tal razón, el bienestar es discutido y contrastado con enfermedad, salud, estrés y destres. Además de esto, la importancia de capacidades prospectivas es discutida en relación al bienestar de animales humanos y no-humanos.

The effects of cadmium exposure on both environment exploration and behavioral responses induced by alarm substance in matrinxã (Brycon amazonicus), a fish species endemic to the Amazon basin, were investigated. Fish exposed to 9.04+/-0.07 microg/L waterborne cadmium for 96h followed by 24h depuration period in clean water, were video-recorded for 15 min, followed by immediate introduction of conspecific skin extract to the tank and a new 30 min period of fish video-recording. Cd-exposed matrinxã showed a significantly lowered locomotor activity (t-test t(12)=2.7; p=0.025) and spatial distribution (t-test t(12)=2.4; p=0.03) relative to the unexposed control fish prior to the alarm substance introduction, and did not present any significant reaction when the skin extract was introduced. The control fish, in opposite, showed a higher level of activity and spatial distribution prior the skin extract contact and significantly decreased their response after the chemical stimulus (locomotion-repeated-measure ANOVA F(1,11)=5.6; p=0.04; spatial distribution F(1,11)=19.4; p=0.001). In conclusion, exposure to a low level of cadmium affects both the environment exploration performance and the conspecific chemical communication in matrinxã. If the reduced environmental exploration performance of Cd-exposed fish is an adjustment to the compromised chemical communication or an independent effect of cadmium is the next step to be investigated.

No Brasil, assim como em outras partes do mundo, a preocupação com o bem-estar dos peixes encontra-se em seus passos iniciais. O bem-estar de peixes, se comparado com o bem-estar de outras espécies de animais de produção, é um tópico praticamente ausente para consumidores, produtores e legislação vigente. Porém, as evidências anatômicas, fisiológicas, comportamentais,evolutivas e farmacológicas sugerem que os peixes experimentam sentimentos como dor, medo e outros de maneira similar aos demais vertebrados. Isso sugere que os peixes têm potencialmente a capacidade de sofrer e apresentar outros sentimentos, ou seja, que os peixes são seres sencientes. Esta revisão teve como objetivo discutir aspectos referentes à dor e à presença de consciência nos peixes, visando colaborar com o entendimento da senciência nesses animais. Uma vez reconhecida a senciência em peixes, estes animais são incluídos nas considerações éticas acerca de não serem submetidos a sofrimento.

The effect of chronic social stress on growth, energetic substrates and hormones was tested in rainbow trout, Oncorhynchus mykiss. After a 14-day isolation period, the fish were paired for 8 days. In order to expose fish to chronic intermittent social contact during pairing, they were maintained in direct contact with each other during the first day. After that, a black plastic screen partition was introduced in each tank, preventing direct contact between animals. Every day the partition was removed for 30 min, allowing physical interaction between fish. At the end of pairing period, they were isolated again for 13 days. Fish were weighed and blood was sampled frequently during the experiment. Plasma levels of cortisol, growth hormone, glucose, total protein and free amino acids were quantified. Both dominants and subordinates had specific growth rate decreased during the pairing period, but only subordinates increased when the stressor was abolished (dominants: 0.32+/-0.21 and 0.24+/-0.41, subordinates: -0.77+/-0.29 and 0.37+/-0.31, respectively). Dominants showed a higher cortisol level one week after pairing condition had been abolished than subordinates (dominants: 56.76+/-13.26, subordinates: 31.89+/-13.36). We conclude that chronic condition of intermittent social stress represents a stressful condition for animals of both hierarchical ranks and a treatment of one daily short direct contact between conspecifics does not promote habituation in fish, as mentioned for other stressors.

Fish welfare issues are predicated on understanding whether fish are sentient beings. Therefore, we analyzed the logic of the methodologies used for studying this attribute. We conclude that empirical science is unable to prove or to disprove that fish are sentient beings. Thus, we propose a combined ethical-scientific approach for considering fish as sentient beings. The most difficult ongoing question is to determine which conditions fish prefer. Approaches to assess fish preferences should be rigorously and cautiously employed. In light of these considerations, attempts to establish physiological standards for fish welfare are discouraged, and a preference-based definition of fish welfare is proposed.

In Brazil, as well as in other parts of the World, the concern about fish welfare is in its initials steps. Fish welfare, if compared to the welfare of other species of farm animals, is practically an absent topic for consumers, producers and current law. However, anatomic, physiologic, behavioral, evolutive and pharmacologic evidences suggest that fish experience feelings such as pain, fear and others, in ways that are similar to other vertebrates. This suggests that fish are potentially capable of experiencing suffering and other feelings; in other words, that fish are sentient. The objective of this review was to discuss pain and consciousness in fish, in order to collaborate with sentience understanding in these animals. Once fishes are recognized as sentient beings, these animals are then included into ethical considerations regarding the avoidance of suffering infliction.