Are there separate circatidal and circadian clocks in the shore crab Carcinus maenas

Self Cite

Newly recruited early juveniles of the shore crab Carcinus maenas in North Wales are most abundant on the high intertidal of gravelly shores and, unlike adults, they do not undertake upand-down shore migration with tides. Freshly collected first and second instar juvenile crabs showed persistent circatidal rhythms of moulting when maintained in constant laboratory conditions. Peaks of moulting occurred around expected times of high tides, with few crabs moulting at other times. The circatidal moulting patterns were similar in crabs collected at different stages of the neap-spring cycle. Daily monitoring of moulting in the laboratory of 23 batches of early crabs, collected from the high intertidal at 1 to 3 d intervals over 2 spring-neap cycles, further showed a marked circasemilunar moulting pattern superimposed on the tidal moulting rhythms. Significantly more crabs moulted within 24 h after collection when collected during spring tides than when collected at neaps. Moreover, the daily percentage moulting of the crabs on consecutive days after collection clearly followed the trend of predicted tidal height changes. Crabs collected on days of increasing tidal amplitude showed increasing moulting rates on the days after collection, whilst a decreasing trend of daily moulting rate was found if they were collected on days of decreasing tidal amplitude. For crabs collected at minimum neaps, when water did not reach the high intertidal even at high tides, virtually no moulting took place on the following days. Moulting at high tide, particularly during spring high tides, appears to be an adaptation to a high intertidal habitat which is only inundated at certain times during semilunar and tidal cycles. For C. maenas early juveniles, which remain in the high intertidal even when tides recede, anticipation of the rising and falling of tides through endogenous physiological programming to avoid ecdysis at the time exposed to air has clear adaptive value. The coupllng of circatidal and circasemilunar moulting rhythms, and their endogenous control, reported in the present study appears to be the first demonstration of such a phenomenon in a crustacean.

Section: Discussionmentioning

confidence: 99%

Endogenous tidal and semilunar moulting rhythms in early juvenile shore crabs Carcinus maenas: implications for adaptation to a high intertidal habitat

Zeng

Abelló²,

Naylor³

1999

Self Cite

“…Ever since a tidal rhythm in behaviour was first discovered in the green turbellarian Convoluta roscoffensis in 1903(Bohn 1903, Gamble & Keeble 1903, many researchers have observed the circadian and circatidal rhythms in many species of marine animals (Reid & Naylor 1989, Northcott et al 1991, Palmer & Williams 1993, Tankersly & Forward 1994, Akiyama 1995, Zeng & Naylor 1996.…”

Section: Introductionmentioning

confidence: 99%

Endogenous circadian rhythm in the river puffer fish Takifugu obscurus

Ws¹,

Jm²,

Sk³

et al. 1997

Oxygen consumption rate of 8 to 12 mo old river puffer fish Takifugu obscurus was determined using a n automatic intermittent-flow-respirometer (AIFR). During the experiments, the fish were not fed and were kept in constant darkness and at constant temperature to avoid any extrinsic disturbances. It was clearly demonstrated that this species has a strong endogenous circadian rhythm in its instantaneous rates of oxygen consumption, although there were weak mlnor peaks of 11 4 to 11.7 h intervals. This endogenous rhythm appeared to be independent of the number of fish in the experimental chamber. The endogenous rhythm in the oxygen consumption rate observed in the present study may have profound implications for the physiological processes and biological rhythms of this species, and could also b e a good reference in determining the oxygen consumption rates of other aquatic organisms.

“…The first is largely based upon studies of the locomotory activity of Carcinus maenas and asserts that endogenous tidal rhythms are controlled by a 'true' circatidal (≈12.4 h) oscillator that interacts with other biological oscillators (e.g. circadian and circalunidian) to produce the complex activity rhythms often observed in intertidal crustaceans (Reid & Naylor 1989, Naylor 1996. Under this scenario, differences in the swimming patterns of U. pugilator zoeae are the result of the differential expression of 2 oscillators with fundamentally different periods of 12.4 h (circatidal) and 24 h (circadian) or possibly 24.8 h (circalunidian; see Palmer 1995b).…”

Section: Discussionmentioning

confidence: 99%

Circatidal swimming behaviors of fiddler crab Uca pugilator larvae from different tidal regimes

López‐Duarte

Tankersley²

2007

Fiddler crab Uca pugilator larvae are released within estuaries near the time of high tide and are exported offshore to undergo development. Previous studies indicate that zoea-1 larvae use selective tidal-stream transport (STST) to migrate from adult habitats to shelf waters. In areas with semidiurnal tides, this behavior is mediated by a circatidal rhythm that is characterized by upward swimming toward the surface during ebb tide, followed by a descent toward the bottom during flood tide. We tested the hypothesis that U. pugilator zoeae from different tidal regimes possess activity rhythms that match local tidal patterns. Ovigerous crabs with late-stage embryos were collected from areas with semidiurnal, diurnal, and mixed tides and from an area within a microtidal coastal lagoon. Following hatching, swimming activity was monitored under constant conditions for 96 h. Zoeae from semidiurnal and diurnal regimes possessed activity rhythms with free-running periods that matched the tides at the collection sites (≈12.4 and 24.8 h, respectively). Crabs from beaches with mixed tides displayed asymmetrical oscillations in swimming activity with dominant periodicities that corresponded to the semidiurnal and diurnal constituents of the tides. Zoeae from microtidal areas possessed rhythms that were similar to those observed in crabs from areas with semidiurnal tides. At all locations, peaks in activity occurred during the time of expected ebb currents, which is consistent with STST behavior favoring seaward transport. Differences in larval activity patterns suggest that STST behaviors are controlled by separate circatidal and circalunidian clocks or paired circalunidian clocks coupled in antiphase.