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- Olfactory sensitivity to conspecific bile fluid and skin mucus in the European eel Anguilla anguilla (L.)Publication . Huertas, Mar; Hubbard, Peter; Canario, Adelino V. M.; Cerda, J.The present study assessed the olfactory potency of conspecific bile fluid and skin mucus in the European eel Anguilla anguilla by the electro-olfactogram. Immature males showed high olfactory sensitivity to conspecific bile, giving large amplitude responses in a concentrationdependent manner with estimated thresholds of detection of <1:107 (n = 6). Mucus also proved to contain highly potent odorants with thresholds of detection of c. 1:106 (n = 6). Crude solidphase extraction of bile fluid (C-18 and C-2/ENV+ cartridges) showed that the majority of olfactory activity in bile fluid was contained in the eluate of C-18 cartridges (n = 6). There were quantitative differences, however, between the sexes; female bile fluid had a higher proportion of activity in this fraction. Similar solid-phase extraction of mucus showed that it contains a higher proportion of odorants in the C-18 filtrate than bile fluid. Mucus from mature eels, however, had a higher proportion of olfactory activity in the eluate than immature fish (n = 6). Cross-adaptation experiments suggest that there are qualitative differences in the odorants contained in bile and mucus depending on both the sex and state of sexual maturation of the donor (n = 6). These results are consistent with a role for chemical communication in the reproduction of the European eel and suggest that both bile and mucus are potential sources of the odorants involved.
- Evidence for involvement of chemical communication in reproduction of the eel Anguilla anguillaPublication . Huertas, Mar; Hubbard, Peter; Scott, A. P.; Canario, Adelino V. M.; Cerda, J.The European eel (Anguilla anguilla) is characterised by long transoceanic migration to spawning sites during which the fish become sexually mature. A previous study demonstrated that mature eels may induce physiological and behavioural changes in immature conspecifics. This raises the possibility that chemical communication may be involved in this process. The aim of the current study was, therefore, to assess the olfactory sensitivity of eels to conspecific-derived odours and to establish whether these odours differ according to sex and/or state of maturity.
- Chemical communication in the Genus Anguilla: a minireviewPublication . Hubbard, Peter; Canario, Adelino V. M.; Huertas, MarEels of the Genus Anguilla are important fish in both scientific and economic terms. Unfortunately, current stocks of the European eel in particular (Anguilla anguilla L.) are becoming increasingly endangered. Chemical communication plays important roles in several key aspects of fish biology. Due to its complex life-cycle, the eel offers a unique opportunity to study various aspects of olfactory biology and chemical communication almost in isolation, feeding (during freshwater ‘yellow’ stage), adaptation to seawater, migration and, finally, reproduction. The aim of this brief review is to summarise what is known about chemical communication in the eel (during reproduction in particular) and, more importantly, stimulate further research. To date, eels have been shown to have high olfactory sensitivity to substances released by conspecifics. Both the bile fluid and skin mucus have been implicated as the routes of release of these odorants but other routes, such as the urine, cannot be excluded. Furthermore, the nature of these odorants depends on both the sex and reproductive status of the donor; exposure to water conditioned by mature con-specifics causes a stimulation of sexual maturation in immature eels. These results are consistent with a role for chemical communication in eel reproduction. The European eel is, therefore, proposed as a model species for studies on olfaction and chemical communication in fish because of its ancestral status, its high olfactory sensitivity and its physiological plasticity. However, more research is necessary; specifically, identification of the key odorants involved, their behavioural and physiological effects and how the olfactory system may change at various stages of its life-cycle.