Delayed metamorphosis in Florida hermit crabs: multiple cues and constraints (Crustacea: Decapoda: Paguridae and Diogenidae)

Abstract

1 examined the effects of food availablllty, shell availability and the presence of adults on survlval and duration of the megalopal stage of the lntertldal h e r m~t crabs Pagurus maclaughlinae Garcla-Gomez, Paguristes tortugae Schmitt and Cllhananus vlttatus (Bosc) In the laboratory. I also cons~dei-ed the role of substrate avdilability on C. vlttatus. All species delayed metamorphosis significantly in the absence of empty shells; shells also enhanced megalopal survival In P, maclaughlinae and C. vittatus. Water that had previously housed conspeclflc adults significantly improved megalopal survival and shortened time to metamorphosis in P. maclauglilinae and P. tortugae. Shell-less megalopae of C. vittatus delayed metamorphosis when kept in adult-conditioned water, but metamorphosed more quickly in the presence of sediment. Food availability did not affect the duration of the megalopal stage in P. maclaughlinae or P. tortugae, whereas starved C. vittatus megalopae died in 8 d or less. Although food availability was associated with somewhat enhanced survival in P. tortugae, the mechanism underlying this effect is unknown, since P. tortugae was not observed to feed a s either megalopae or zoeae. As in other species of Pagt~rus, megalopae of P. tnaclaughlinae were not observed to feed, whereas zoeae and juveniles did feed. The differences and similarities in the nature and extent of the delay capabilities of P. maclaughlinae, P. tortugae and C. vittatus appear to reflect the interaction among various aspects of the ecology of the adults a n d energetic constraints on the megalopae.

Delayed metamorphosis of a tropical reef fish (Acanthurus triostegus):a field experiment

“…The paucity of evidence for demersal fishes contrasts with an extensive body of invertebrate literature, for which delays in settlement are well documented and experimentally examined (e.g. Richmond 1985, Lipcius et al 1990, Pechenik 1990, Pechenik et al 1993, Davis 1994, Harvey 1996, Stoner et al 1996. The present study is the first to experimentally examine in the field the capacity of a fish species to delay metamorphosis.…”

Effects of substratum and conspecific adults on the metamorphosis of Chasmagnathus granulata (Dana) (Decapoda: Grapsidae) megalopae

“…Substances released by conspecifics should be relevant stimuli indicating an adequate habitat (Jensen, 1989). Also, low salinity and estuarine vegetation (Wolcott and De Vries, 1994;Forward et al, 1994Forward et al, , 1996, or substratumrelated cues (Christy, 1989;Harvey, 1996;Weber and Epifanio, 1996) have been identified as effective cues.…”

“…Recent experiments by Weber and Epifanio (1996) showed that stimuli related to the preferred adult substrata, as well as the presence of adult conspecifics, can induce metamorphosis in competent megalopae of Panopeus herbstii. Also, Harvey (1996) demonstrated that the time to metamorphosis was affected in two hermit crabs, Pagurus maclaughlinae and Paguristes tortugae, by exposure to adultconditioned water and in another hermit crab, Clibanarius vittatus, by the presence of sediment.…”

Duration of the pre-settlement period of the mangrove crab Ucides cordatus (Decapoda: Ocypodidae) under laboratory conditions

“…The main methodological difference between the present study and that of Rodrigues and Hebling (1989) was the presence of the mangrove sediment within the experimental container. The physicochemical characteristics of the substrates might strongly modulate the decapod metamorphosis, such as temperature (Jamieson and Phillips, 1993;McMillan et al, 1995;Anger et al, 2004), salinity (Islam et al, 2005), and conspecific chemical cues (Harvey, 1996;O'Connor and Judge, 1997;Gebauer et al, 1998;Rodríguez and Epifanio, 2000;Gebauer et al, 2002). Future studies, addressing specifically this issue, could provide important information to accelerate the larval development of U. cordatus and to optimize their larviculture.…”