The annual pattern of feeding, growth, and sexual reproduction in Cyanea (Cnidaria: Scyphozoa) in the Niantic River Estuary, Connecticut
Brewer, R.H. (1989). The annual pattern of feeding, growth, and sexual reproduction in Cyanea (Cnidaria: Scyphozoa) in the Niantic River Estuary, Connecticut. Biol. Bull. 176(3): 272-281. https://dx.doi.org/10.2307/1541985
In: The Biological Bulletin. Marine Biological Laboratory: Lancaster. ISSN 0006-3185; e-ISSN 1939-8697, more
|   |
| Keywords |
Cyanea Péron & Lesueur, 1810 [WoRMS]
Brackish water |
| Abstract |
The seasonal occurrence, population dynamics, feeding, growth, reproduction, and timing of planular deposition was determined for a semelparous annual population of Cyanea medusae in the Niantic River estuary, Connecticut, which was sampled for 14 years. The annual pattern was highly predictable. Their ephyrae appear shortly after ice-out in late February, medusae with gonads occur in late April-early May, and are reproductive (bearing planulae on their oral folds) by late May-early June. At this time (early to mid-June), the medusae deteriorate, disappearing from the plankton in late June-early July. Population size, similarly, exhibits small variation, showing only a 5-fold difference in anbundance. With deterioration, the frequency of feeding medusae declines; otherwise, they are opportunistic predators on seasonally numerous zooplankton, including fish. Growth shows two phases: first, a three month period of rapid exponential growth when medusae mature; and second, a one and one half month period of decline in average size of individuals as the larger medusae die. Medusae exhibit a sequence of "organ" loss prior to death: first, the tentacles, then the oral folds, and last, the gonads. Coincident with the disappearance of these organ-deficient medusae from the water column, their planulae first appear attached to shells in the benthos. The deterioration of medusae, and in particular the loss of planulae-bearing oral folds, may be requisite for the mass release of their planulae. |
|
