Reproductive cycles in tropical intertidal gastropods are timed around tidal amplitude cycles

Abstract

Reproduction in iteroparous marine organisms is often timed with abiotic cycles and may follow lunar, tidal amplitude, or daily cycles. Among intertidal marine invertebrates, decapods are well known to time larval release to coincide with large amplitude nighttime tides, which minimizes the risk of predation. Such bimonthly cycles have been reported for few other intertidal invertebrates. We documented the reproduction of 6 gastropod species from Panama to determine whether they demonstrate reproductive cycles, whether these cycles follow a 2‐week cycle, and whether cycles are timed so that larval release occurs during large amplitude tides. Two of the species (Crepidula cf. marginalis and Nerita scabricosta) showed nonuniform reproduction, but without clear peaks in timing relative to tidal or lunar cycles. The other 4 species show clear peaks in reproduction occurring every 2 weeks. In 3 of these species (Cerithideopsis carlifornica var. valida, Littoraria variegata, and Natica chemnitzi), hatching occurred within 4 days of the maximum amplitude tides. Siphonaria palmata exhibit strong cycles, but reproduction occurred during the neap tides. Strong differences in the intensity of reproduction of Cerithideopsis carlifornica, and in particular, Littoraria variegata, between the larger and smaller spring tides of a lunar month indicate that these species time reproduction with the tidal amplitude cycle rather than the lunar cycle. For those species that reproduce during both the wet and dry seasons, we found that reproductive timing did not differ between seasons despite strong differences in temperature and precipitation. Overall, we found that most (4/6) species have strong reproductive cycles synchronized with the tidal amplitude cycle and that seasonal differences in abiotic factors do not alter these cycles.

Coupling of coastal activity with tidal cycles is stronger in tool-using capuchins ( Cebus capucinus imitator )

“…Additionally, oceans are also seasonal and, as such, resources in the intertidal zone likely vary spatially and temporally across seasons (e.g. snails [ 76 ]). However, for tool-using capuchins, exploitation of intertidal resources might not be driven by a scarcity of terrestrial resources: in the wet season, there is likely peak availability of one of the tool-users most consumed resources, Terminalia catappa, which bears fruit from January to April and from May to September [ 77 ].…”

Seaward migration and larval release of the land hermit crab <i>Coenobita</i> <i>brevimanus</i> Dana, 1852 (Anomura: Coenobitidae) on Iriomote Island, Japan

“…To determine whether intervals of seawardmigration/larval release for C. brevimanus are correlated with lunar (29.5 days) or semi-lunar (14.8 days) cycles or with the size of the spring tides, circular plots of the timing of reproduction with phases of the moon and with the spring-neap tidal cycles (14.8-day cycles of the difference in height between high and low tides taken over a day) were used (Collin et al 2017). The number of crawling/releasing crabs encountered on each date was plotted against dates (degrees) with the new moon or the spring tides as 0°.…”

Coupling of Coastal Activity with Tidal Cycles is Stronger in Tool-using Capuchins (Cebus capucinus imitator)

“…It is important to consider that capuchins are dietary generalists who not only consume fruits but also insects and other invertebrates, which have their own seasonal fluctuations. Additionally, oceans are also seasonal and, as such, resources in the intertidal zone likely vary spatially and temporally across seasons (e.g., snails, Collin et al, 2017). However, for tool-using capuchins, exploitation of intertidal resources might not be driven by a scarcity of terrestrial resources: in the wet season there is likely peak availability of one of the tool-users most consumed resources, Terminalia catappa, which bears fruit from January to April and from May to September (Perez & Condit, n.d.).…”