In 1993 I initiated a long-term study of the ecology and behaviour of the European bitterling, Rhodeus sericeus. This species has an obligate spawning relationship with living freshwater mussels, Unionidae. Males defend territories around mussels, and attract females, which insert an ovipositor through the exhalent siphon of the mussel to deposit a few eggs into the mussels’ gills. The male fertilises the eggs by releasing sperm over the inhalent siphon. After repeated spawnings by many females, mussels may contain over 100 eggs. These remain inside the mussels for several weeks until the yolk sacs of the embryos have been resorbed, whereupon the young fish leave via the exhalent siphon. Various people have joined this project as postdocs and PhD students, including Marc Naura, Henri Guillaume, Carl Smith, Suzie Mills and Ulrika Candolin.
Related articles (see Publications page):
Mills, S.C., Taylor, M.I., & Reynolds, J.D. (2005) Benefits and costs to mussels from ejecting bitterling embryos: a test of the evolutionary equilibrium hypothesis. Animal Behaviour 70, 31-37.
Mills, S.C. & Reynolds, J.D. (2004) The importance of species interactions in conservation: the endangered European bitterling, Rodeus sericeus and its freshwater mussel hosts. Animal Conservation 7, 257-263.
Mills, S.C. & Reynolds, J.D. (2003a) Operational sex ratio and alternative reproductive behaviours in the European bitterling, Rhodeus sericeus. Behavioral Ecology & Sociobiology 54, 98-104.
Mills, S.C. & Reynolds, J.D. (2003b) The bitterling-mussel interaction as a test case for co-evolution. Journal of Fish Biology 63(Supplement A), 84-104.
Candolin, U. & Reynolds, J.D. (2002) Adjustments of ejaculation rates in response to risk of sperm competition in a fish, the bitterling (Rhodeus sericeus). Proceedings of the Royal Society of London B. 269, 1459-1553.
Candolin, U. & Reynolds, J.D. (2002) Why do males tolerate sneakers? Tests with the European bitterling, Rhodeus sericeus. Behavioral Ecology & Sociobiology 51, 146-152.
Mills, S.C. & Reynolds, J.D. (2002) Host preferences by bitterling (Rhodeus sericeus) spawning in freshwater mussels and consequences for offspring survival. Animal Behaviour 63, 1029-1036.
Mills, S.C. & Reynolds, J.D. (2002) Mussel ventilation rates as a proximate cue for host selection by bitterling, Rhodeus sericeus. Oecologia 131, 473-478.
Candolin, U. & Reynolds, J.D. (2001) Sexual signaling in the European bitterling: females learn the truth by inspecting the resource. Behavioral Ecology 12, 407-411.
Smith, C., Reynolds, J.D. & Sutherland, W.J. (2000) Population consequences of reproductive decisions. Proceedings of the Royal Society of London B 267, 1327-1334.
Smith, C., Reynolds, J.D., Sutherland. W.J. & Jurajda, P. (2000) Adaptive host choice and avoidance of superparasitism in the spawning decisions of bitterling (Rhodeus sericeus). Behavioral Ecology and Sociobiology 48, 29-35.
Reynolds, J.D. & Guillaume, H.P. (1998) Effects of phosphate on the reproductive symbiosis between bitterlings and freshwater musseals: implications for conservation. Journal of Applied Ecology 35, 575-581.
Reynolds, J.D., Debuse, V.J. & Aldridge, D.C. (1997) Host specialisation in an unusual symbiosis: European bitterlings spawning in freshwater mussels. Oikos 78, 539-545