Cues for Metamorphosis of Brachyuran Crabs: An Overview

Forward, Richard B.; Tankersley, Richard A.; Rittschof, Dan

doi:10.1093/icb/41.5.1108

Cited by 58 publications

(89 citation statements)

References 63 publications

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“…The ontogenetic transition from a pelagic to a bottom-dwelling lifestyle is in most cases associated with dramatic behavioural and developmental changes, which are generally referred to as settlement and metamorphosis, respectively. While some species may pass spontaneously through these crucial life-history events, following only a genetically fixed and hormonally controlled developmental programme, others also respond to environmental cues that are usually linked to the adult habitat or to the presence of conspecific adults (for recent review, see Forward et al, 2001, Gebauer et al, 2003. When effective external cues are absent, "competent" larvae (i.e., those being physiologically and morphologically prepared for settlement and metamorphosis) may postpone the initiation of these developmental processes, remaining for an additional period in the plankton.…”

Section: Introductionmentioning

confidence: 99%

Temporal window of receptivity and intraspecific variability in the responsiveness to metamorphosis-stimulating cues in the megalopa of a semi-terrestrial crab,Sesarma curacaoense

Gebauer

Paschke

Anger

2005

Invertebrate Reproduction & Development

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SummaryThe larvae of numerous sessile and several motile marine invertebrate species respond to metamorphosis-stimulating cues, usually chemical signals from their benthic habitat. In three series of experiments (I-III), the megalopa larvae of a semi-terrestrial mangrove crab, Sesarma curacaoense de Man, were exposed for differential periods to adult-conditioned water (ACW), which had previously been found an effective cue. In the first experimental series (Exp. I), ACW was added on successively later days of the moulting cycle, while Exp. II comprised treatments in which the cues were provided from the first day (postmoult) and removed on sucessively later days. In Exp. III, the megalopae were exposed to ACW for 3 days at the beginning, in the middle, or near the end of the moulting cycle (days 1-3, 4-6, and 7-9, respectively). All experimental series also comprised a permanently exposed control group (C+) and another one kept in complete absence of the cue (C!), and all experiments were repeated with larvae originating from three different females (F1-F3 in Exps. I and II; F4-F6 in Exp. III). Both the timing and duration of exposure to ACW had a significant influence on the duration of development to metamorphosis, indicating an interaction between the extrinsic signal and the intrinsic (hormonal) control of the moulting cycle. While continuously exposed control megalopae (C+) required on average 7.6 ± 0.5 to 7.7 ± 0.5 d, those in group C! delayed their development by about 3-4 d (or on average by 48%), 7-9 d (119%), and 5-6 d (61%), respectively (F1-F3), indicating a great deal of intraspecific variability among hatches. In Exp. I, the cue had to have been added within about the first 6-7 d to become effective (no significant difference in development time between treatments and control C+), while a later addition of ACW had no more stimulating effect (no difference to C!). In Exp. II, metamorphosis was delayed in all treatments when the cue was removed after an initial exposure of less than 4-5 d, while later removal did not significantly reduce the stimulating effect of ACW. Together, the results from these two experimental series suggest that an exposure approximately during days 4-6 of the moulting cycle may be crucial as a temporal window of receptivity for the cue; this period coincides with the transition between intermoult and premoult (stages C-D 0 of Drach's classification system). Its presumable importance as a critical point was confirmed in Exp. III where development time was consistently shortest in megalopae exposed only during days 4-6 of the moulting cycle (no significant difference to control C+), while an earlier or later exposure prolonged development to metamorphosis. Intraspecific variability in the responsiveness to P. Gebauer et al. / IRD 47 (2005) 39-50 ACW was tested by comparing development time in control groups (C+, C!) among megalopae from 14 different hatches (including F1-F6). These data showed a significant variability both in the delay due to complete absence of the cue and ...

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Section: Introductionmentioning

confidence: 99%

Temporal window of receptivity and intraspecific variability in the responsiveness to metamorphosis-stimulating cues in the megalopa of a semi-terrestrial crab,Sesarma curacaoense

Gebauer

Paschke

Anger

2005

Invertebrate Reproduction & Development

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“…These clear, rapid changes in relative abundance of planktonic megalopae of Uca minax, U. pugnax and U. pugilator may have indicated a direct response of megalopae to salinity in the water column. Megalopae of U. pugilator and U. pugnax may suffer high mortalities at lower salinities or they may settle out of the water column in areas closer to the mouth of the estuary in response to the spatial shift in salinity caused by freshwater influx (Forward et al 2001). This latter scenario is supported by O'Connor & Epifanio (1985), who inferred from their data that megalopae seek out adult conspecific salinity regimes.…”

Section: Discussionmentioning

confidence: 89%

“…Salinity impacts the distribution (Gunter 1956), biodiversity (Duke et al 1998), recruitment (Forward et al 2001) and survival (Sandison 1966) of estuarine organisms. Odum (1988) and Vernberg (1993) noted that freshwater flow from rain events altered the existing assemblage of organisms in an estuary, and stated that more studies need to be conducted on salinity because it affects the vast majority of estuarine biota.…”

Section: Introductionmentioning

confidence: 99%

Effect of summer storms on early life stages of Uca minax, U. pugnax and U. pugilator in North Inlet Estuary, South Carolina, USA

Godley¹,

Brodie²

2007

Mar. Ecol. Prog. Ser.

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Estuarine fiddler crabs have a complex life cycle that spans vastly different salinity regimes. Larvae are spawned in estuaries and travel to the coastal ocean where development takes place; after metamorphosing to the megalopal stage, fiddler crabs reinvade estuaries where they settle and metamorphose. In the coastal ocean, larvae experience relatively stable physical conditions; however, upon reinvading estuaries, they are exposed to great fluxes in salinity and temperature. In this study, we measured shifts in the salinity regime caused by storm events, and determined the impact of these changes on species frequencies of megalopae from 3 Uca species in the water column and of their recently settled juvenile crabs on the benthos along a salt marsh creek in South Carolina. Adults of the 3 species examined are found in different salinity regimes: adult Uca pugnax generally occupy areas with relatively high salinity and plant cover, while U. minax are found in low salinity or freshwater areas; U. pugilator are found in open sandy areas over a broad range of salinities, but generally occupy higher salinity environments than U. minax. For megalopal stages in the water column, we found that the relative proportions of the 3 species changed significantly along salinity gradients and in response to storm events. When the salinity regime normalized, species frequencies for megalopae returned to pre-storm proportions. Only U. minax megalopae were present in the water column during a storm event in July, whereas U. pugnax had been the most abundant species in the water column prior to the storm. Although all 3 species were able to survive storm events as juveniles, U. pugnax juveniles survived low salinity conditions significantly better than the other 2 species during the July storm. During a less severe storm in August, which lasted 5 d and altered the existing profile for a week, the benthic juvenile stages did not exhibit significant changes in species frequencies. Our results show that the duration and severity of salinity change are important variables that impact on the presence of these Uca species in the water column, and suggest that the physiology and behavior of the megalopal stage strongly influence where populations occur within estuaries.KEY WORDS: Salinity · Tolerance · Uca spp. · Estuarine crabs 342: 197-204, 2007 this investigation allowed us to explore how changes in species frequencies of early life stages under shifting salinity regimes could lead to changes in the distribution of these species across the marsh landscape. Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerLike most estuarine invertebrates, fiddler crab (Uca spp.) have complex life cycles that include life stages that occupy different habitats. The adults live and spawn in the estuary (salinity range from 0 to 32 psu) and larvae are dispersed into the coastal ocean (salinity ~35 psu) where larval development is completed. Fiddler crab megalopae (also known as post-larvae) reinva...

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“…In this case, the presence of adults can be viewed as an indirect cue of favorable habitat, as suggested by others (e.g. Forward et al, 2001;Donahue, 2006), but, as long as we are aware, information on how early settlers respond to such cues as to improve resource use is still lacking.…”

Section: Introductionmentioning

confidence: 99%

“…It is widely recognized that late larvae of marine invertebrates make extensive use of environmental cues to locate, and remain, in favorable habitat (e.g., Forward et al, 2001;Pineda et al, 2010). Conspecific cues, in particular, can be important by increasing settlement rates of larvae (Burke, 1986;Smith & Peacock, 1990), and stimulating metamorphosis to the juvenile stage (Fitzgerald et al, 1998;Simith & Diele, 2008).…”

Section: Introductionmentioning

confidence: 99%

Conspecific cues affect stage-specific molting frequency, survival, and claw morphology of early juvenile stages of the shore crab Carcinus maenas

Duarte

Flores

et al. 2013

Hydrobiologia

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2014Conspecific cues affect stage-specific molting frequency, survival, and claw morphology of early juvenile stages of the shore crab Abstract Benthic conspecific cues are used by competent larvae of many marine invertebrates to locate and settle on suitable habitat. However, aggregations of conspecifics can generate strong intraspecific competition and inter-cohort cannibalism. We investigated the effects of adult conspecific cues on general fitness parameters of juvenile Carcinus maenas (stages J1-J5), and used geometric morphometrics to investigate patterns of allometric growth indicative of life-history strategies and resource use potential. Cues induced faster metamorphosis and slightly shortened intermolt time in J2 individuals, at the expense of acute mortality in J1 crabs. These effects are cumulative but compensatory processes nullify differences by the end of the experiment. Allometric carapace change toward the adult standard remained unchanged, but conspecific cues induced first a change in size (J1) and then in shape (J5) of claws. In both control and cued juveniles, heterochely was incipient but apparent in J5 crabs. Independently of body side, conspecific cues triggered a very marked increase of the propodus posterior margin, presumably enhancing general strength. Therefore, early benthic stages may grow slightly faster to a size refuge, and develop stronger claws providing competitive advantage for the use of high-value food items when population density-dependent processes are more probable.

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Cues for Metamorphosis of Brachyuran Crabs: An Overview

Cited by 58 publications

References 63 publications

Temporal window of receptivity and intraspecific variability in the responsiveness to metamorphosis-stimulating cues in the megalopa of a semi-terrestrial crab,Sesarma curacaoense

Temporal window of receptivity and intraspecific variability in the responsiveness to metamorphosis-stimulating cues in the megalopa of a semi-terrestrial crab,Sesarma curacaoense

Effect of summer storms on early life stages of Uca minax, U. pugnax and U. pugilator in North Inlet Estuary, South Carolina, USA

Conspecific cues affect stage-specific molting frequency, survival, and claw morphology of early juvenile stages of the shore crab Carcinus maenas

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