Triggering larval settlement behaviour and ...

CSIRO PUBLISHING

Marine and Freshwater Research http://dx.doi.org/10.1071/MF14326

Triggering larval settlement behaviour and metamorphosis of the burrowing ghost shrimp, Lepidophthalmus siriboia (Callianassidae): do cues matter? Ka´cia Letı´cia de Noronha Campos A, Fernando Arau´jo Abrunhosa A and Darlan de Jesus de Brito Simith A,B,C A

Laborato´rio de Carcinologia, Instituto de Estudos Costeiros (IECOS), Universidade Federal do Para´ (UFPa), Campus Universita´rio de Braganc¸a, Alameda Leandro Ribeiro s/n, Aldeia, 68600-000, Braganc¸a, Para´, Brazil. B Laborato´rio de Ecologia de Manguezal (LAMA), Instituto de Estudos Costeiros (IECOS), Universidade Federal do Para´ (UFPa), Campus Universita´rio de Braganc¸a, Alameda Leandro Ribeiro s/n, Aldeia, 68600-000, Braganc¸a, Para´, Brazil. C Corresponding author. Email: [email protected]

Abstract. Larval settlement and metamorphosis of many estuarine decapod crustaceans are triggered by environmental cues and chemical substances produced by the conspecific population. Here, we examined the influence of substrata and conspecific cues on the stimulation of the megalopal stage of the burrowing ghost shrimp (Lepidophthalmus siriboia) in the following five treatments: (1) adult-conditioned seawater (ACSW), (2) filtered seawater (FSW) þ sand, (3) FSW þ muddy sand (MS), (4) ACSW þ MS and (5) FSW without cues (control). All megalopae settled and exhibited burrowing behaviour in the treatments containing substratum. The percentage of metamorphosis to juvenile was high ($96%) in all treatments. Megalopae developed significantly faster in the control (5.7 days, 0.9 s.d.) than in the remaining treatments (6.8–7.3 days). These findings demonstrated that settlement of L. siriboia megalopae is strongly induced by substrata, whereas their metamorphosis occurs irrespective of the presence or type of exogenous cues associated with estuarine habitat and conspecific adults. This suggests certain flexibility concerning the ontogenetic stage at which recruitment to the benthos occurs. The independence of metamorphic inducers should be important for colonisation of new estuarine areas as well as for recovery and maintenance of viable populations in disturbed habitats where callianassid ghost shrimps are heavily exploited. Additional keywords: Axiidea, burrowing activity, cryptic behaviour, juvenile, megalopa, recruitment. Received 14 October 2014, accepted 2 February 2015, published online 22 June 2015

Introduction Many marine and estuarine invertebrates exhibit a complex life cycle involving a meroplanktonic larval and a definitive sessile or motile benthic juvenile–adult phase. For these organisms, the larval settlement in a favourable benthic microhabitat and metamorphosis to first juvenile stage represent critical events during the plankton-to-benthos transition (Chia and Rice 1978; Anger 2001, 2006; Heyland and Moroz 2006). These two processes are extremely important in the context of supply-side ecology, by affecting the likelihood of successful recruitment, maintenance and stability of benthic marine populations and communities (Underwood and Fairweather 1989; Grosberg and Levitan 1992; Rodrı´guez et al. 1993; Anger 2001, 2006). In several marine invertebrate taxa including decapod crustaceans, the larval settlement behaviour and metamorphosis are induced by natural physicochemical or biological stimuli (i.e. cues) that are typically found in the habitat where the Journal compilation Ó CSIRO 2015

conspecific populations live (see review in Pawlik 1992; Rodrı´guez et al. 1993; Anger 2001; Forward et al. 2001; Hadfield and Paul 2001). Studies have shown, for example, that natural substrata (e.g. sand, mud, stone), water-soluble chemical substances (i.e. referred to as ‘odours’ in the literature) emitted by conspecific (or interspecific) adults and benthic microbial biofilms attached to abiotic surfaces may play an important role on the stimulation of the last larval stage (i.e. megalopa) of decapod species, such as, for instance, Chasmagnathus (Neohelice) granulata (see Gebauer et al. 1998), Hemigrapsus sanguineus (see Kopin et al. 2001; Steinberg et al. 2007, 2008; O’Connor 2008; Anderson and Epifanio 2009), Panopeus herbstii (see Weber and Epifanio 1996; Rodriguez and Epifanio 2000; Andrews et al. 2001), Sesarma curacaoense (see Gebauer et al. 2002), Uca pugnax (see O’Connor and Van 2006), U. vocator (see Simith et al. 2010) and Ucides cordatus (see Diele and Simith 2007; Simith and Diele 2008b). The presence www.publish.csiro.au/journals/mfr

B

Marine and Freshwater Research

of environmental and conspecific cues significantly enhances larval survival and accelerates the developmental time of megalopae through metamorphosis (Forward et al. 2001). Moreover, multiple environmental cues working in synergism may result in a stronger larval response than do cues alone (e.g. O’Connor 1991; Gebauer et al. 1998; O’Connor and Van 2006; Diele and Simith 2007; Anderson and Epifanio 2009). In the absence of suitable environmental cues that indicate an appropriate habitat for the early juvenile development, competent larvae of decapod crustaceans can delay their settlement and metamorphosis from hours to months, which may cause an increased mortality before changing to the benthic life style (see review in Pechenik 1990; Forward et al. 2001; Gebauer et al. 2003). Furthermore, a delay of larval metamorphosis may carry highly significant costs to the early post-larval performance of benthic juveniles (i.e. reduced survival and low growth rate; see Pechenik et al. 1998; Gebauer et al. 1999, 2003; Pechenik 2006; Simith et al. 2013). In addition, a prolonged larval life may enhance the risk of predation because of the time spent in the planktonic environment (Morgan 1995). Although numerous studies have been conducted to investigate the importance of suitable habitat cues on the larval settlement and metamorphosis of diverse marine and estuarine invertebrate phyla (reviewed by Pawlik 1992; Rodrı´guez et al. 1993; Anger 2001, 2006; Forward et al. 2001; Gebauer et al. 2003), few investigations have been conducted with burrowing shrimps (Decapoda) belonging to the Callianassidae family. Callianassid ‘ghost’ shrimps are important components of benthic macrofaunal assemblages; they have a key ecological role by promoting sediment turnover (e.g. bioturbation) and nutrient cycling in marine costal ecosystems (Suchanek 1983; Berkenbusch and Rowden 1999; Felder 2001; Webb and Eyre 2004). Laboratory investigations have shown, for example, that larval settlement of the burrowing ghost shrimps Callichirus major and C. islagrande is triggered in response to substratum originating from the parental estuarine habitat (Strasser and Felder 1998, 1999a, 1999b). These studies also demonstrated that the last larval stage of these species exhibits a burrowing behaviour in the presence of sand substratum (Strasser and Felder 1998, 1999a, 1999b). However, for the callianassid Lepidophthalmus siriboia (Felder and Rodrigues 1993), the influence of estuarine cues on the induction of larval settlement and metamorphosis has not been investigated. Also, the burrowing activity and cryptic life style of the settlement stage of this species have not yet been described in the scientific literature. L. siriboia is a semi-terrestrial burrowing ghost shrimp widely distributed along the tropical Atlantic coast of The Americas, ranging from the State of Florida (USA) to the States of Para´, Maranha˜o, Paraı´ba and Bahia (Brazil) (Rodrigues and Shimizu 1998; Melo 1999). Its meroplanktonic development consists of three lecithotrophic zoeae and a last planktotrophic larval stage termed as megalopa (i.e. decapodid; Abrunhosa et al. 2005, 2008). According to some authors, newly hatched zoea-larvae of L. siriboia from the northern Brazilian population are dispersed outside the parental estuaries to complete their development in higher-salinity conditions (Oliveira et al. 2012; D. R. F. Arau´jo, F. A. Abrunhosa, and D. J. B. Simith, unpubl. data). If L. siriboia larvae are in fact ‘exported’, the megalopal stage subsequently migrates back upstream to the estuarine system. Hence, the

K. L. de Noronha Campos et al.

larval responsiveness to environmental cues should be ecologically important during re-immigrations by facilitating habitat selection and gregarious settlement near conspecific shrimp populations. In the field, small burrows with early juveniles of L. siriboia are frequently found close to large conspecific adult burrows, indicating a gregarious settlement of this species (D. J. B. Simith, pers. comm.). In other species, e.g. Callianassa japonica, newly settled recruits are also found within the burrows of conspecific adults (see Tamaki et al. 1992). Thus, on the basis of the life-cycle history and ecological traits of callianassid ghost shrimps, we hypothesised that settlement and metamorphosis of L. siriboia megalopae are mediated by exogenous cues originating from the parental estuarine habitat. As reported in other studies with decapod species (see Anger 2001; Forward et al. 2001; Gebauer et al. 2003), these cues could also include chemical odours released by conspecific adult shrimps working as settlement- or metamorphosis-stimulating cues. In several parts of the world, including the Brazilian Atlantic coast, ghost shrimps are intensively harvested for utilisation as live baits in artisanal and sport fisheries (e.g. C. major (see Borzone and Souza 1996; Souza and Borzone 2003), L. manningi (see Felder and Staton 2000), Upogebia africana (see Hodgson et al. 2000), Trypaea australiensis (see Contessa and Bird 2004)). In the northern Brazilian estuaries, information regarding the exploitation of L. siriboia is scarce; however, there are recent remarks about the utilisation of this species during recreational and artisanal fisheries. Thus, experimental studies on the larval settlement and metamorphosis of callianassid ghost shrimps could reveal how and whether affected populations are being naturally recovered in estuarine habitats affected by human harvestings. Therefore, in the present laboratory study, we experimentally investigated the influence of potential habitat cues (sand, muddy sand) and conspecific adult odours (shrimpconditioned seawater) on the induction of settlement and metamorphosis of L. siriboia megalopae. We also examined whether muddy-sand substratum plus conspecific cues act synergistically on the larval stimulation of this species. Knowledge about larva– environment interactions is important for a better understanding of the biphasic life cycle and patterns of larval recruitment and settlement. These events are, therefore, strongly related to the structure, dynamic and maintenance of marine soft-sediment communities (Underwood and Fairweather 1989; Grosberg and Levitan 1992; Rodrı´guez et al. 1993; Anger 2001, 2006). Materials and methods Seawater for larval rearing Seawater (salinity 35) utilised for larval rearing of Lepidophthalmus siriboia was collected 50 km off the Braganc¸a coastal region (northern Brazil; 08310 41.3700 S, 468150 55.3000 W) to avoid chemical cues carried from the Caete´ estuary. The water was filtered (Eheim and Diatom Filter: 1 mm) and stored in tanks (500 L) with constant aeration in the laboratory. The seawater was diluted with appropriate amounts of distilled tap water to obtain a salinity of 30 for larval culture. Salinity was measured with a WTW-LF 197 probe and a hand-held refractometer (S/Mill-E, Atago, Ribeira˜o Preto, Sa˜o Paulo, Brazil) to the nearest 0.1 and 1 respectively. The pH of the diluted seawater was adjusted to values between 7.5 and 8.0 by using biological

Settlement and metamorphosis of ghost shrimp larvae

filters (i.e. biofilters) basically composed of crushed oyster shells. This calcareous substratum provides sodium carbonate and sodium bicarbonate ions (buffering substances), which are slowly dissolved into the water, thus increasing and stabilising pH. The pH values were measured with a pH-710 probe (Instrutherm, Sa˜o Paulo, Brazil). Prior to the beginning of the experimental treatments (see below), the seawater was biologically filtered (with biofilters) under constant aeration to keep ammonium and nitrite concentrations low. Biofilters have been used to keep the water quality favourable for the culture of crustacean larvae (Valenti et al. 2010, and references cited therein). The biofilters were built with crushed oyster shells that were previously sterilised at 1208C (1 kg cm2) in an autoclave (Prismatec-CS, Sa˜o Paulo, Brazil). Thereafter, these substrata were enclosed in buckets (20 L) containing a PVC system that promoted the continuous water circulation throughout the substratum layer, using strong aeration provided by small-bore rubber tubes. The aeration also provided a source of dissolved oxygen to supply the nitrifying bacteria. After a period of ,20–30 days, the substratum was entirely colonised by microbial biofilms composed of two groups of nitrifying bacteria; the first group converts ammonium to nitrite and the second one converts nitrite to nitrate. Detailed information about construction, functioning and types of biofilters can be found in Valenti et al. (1998, 2009, 2010), New (2002) and Timmons et al. (2002). Two biofilters were then submerged within 500-L tanks and the seawater was filtered for a period of 20 days before larval culture. Larval origin and rearing conditions Lepidophthalmus siriboia zoea-larvae were obtained from three ovigerous females (body length 5.9 cm, 0.4 s.d.) collected in the intertidal zone of the Caete´ estuary (northern Brazil; 08500 06.8500 S, 468360 06.4300 W) on 3 March 2012. The ghost shrimps were extracted from their galleries with a hand-operated suction pump (‘yabby’ pump; 1-m height and 5-cm diameter) and conditioned in aquaria filled with local seawater (salinity 30) and muddy-sand substratum to avoid stress and physical damage to the egg mass. Thereafter, the egg-bearing females were transported to the laboratory where they were kept separately in glass aquaria (15 L) containing filtered seawater, under constant aeration. The females were maintained in the laboratory for 3 days at an ambient temperature of 26.08C (1.0 s.d.),

Marine and Freshwater Research

C

salinity 30, pH 8.0, natural light cycle and without food until the larval release. After spawning, the females were returned to their natural habitat of origin. After hatching (6 March 2012, at 1900 hours), the zoealarvae originating from the three different females were mixed in a glass beaker (5000 mL) and transferred (using wide-bore pipettes) to polyethylene aquaria (1 L) where they were cultivated at a density of ,100 larvae L1. The larvae were reared under natural conditions of temperature (26.58C, 0.5), salinity 30 (a favourable salinity condition for culture of decapod larvae from northern Brazil, see Diele and Simith 2006; Simith and Diele 2008a; Simith et al. 2012, 2014), pH 8.0, photoperiod regime (12 h light/12 h dark) and constant aeration in the culture media. The L. siriboia zoea-larvae (ZI–ZIII) were not fed as they exhibit a lecithotrophic behaviour during their development (see Abrunhosa et al. 2005, 2008). Larvae were checked daily for mortality. After reaching the ZIII stage, larvae were monitored three times a day for moults to the megalopal stage. The culture medium was renewed every 2 days. Experimental design for megalopal rearing In order to verify the influence of two different substrata and chemical substances from conspecific adults on the larval settlement and metamorphosis of Lepidophthalmus siriboia, 250 freshly moulted megalopae originating from laboratory-reared zoeae were randomly distributed in four experimental treatments and a control group (see Table 1). Each treatment was conducted with 50 megalopae that were individually reared in 150-mL plastic recipients until metamorphosis to first juvenile stage (JI). All larvae originating from the three different females developed along three lecithotrophic zoeal stages (ZI–ZIII) and were 4 days old when they synchronously moulted to megalopa. The abiotic conditions (e.g. temperature, salinity, pH) during the megalopal rearing were the same as for zoeae, but without aeration in the culture media. Megalopae were fed ad libitum with newly hatched brine shrimp Artemia sp. (at a density of ,3 nauplii mL1) because this stage has already a feeding behaviour in contrast to the previous zoeal stages (Abrunhosa et al. 2008). The rearing water and food were changed every second day. At the same time, newly collected substrata and fresh shrimp-conditioned seawater were provided (for experimental setup and descriptions, see Table 1). For conditioning the seawater, only recently captured and intact

Table 1. Experimental design and description of treatments for rearing of burrowing ghost shrimp (Lepidophthalmus siriboia) megalopae Treatment

Description

1. Adult-conditioned seawater (ACSW)

Filtered seawater that was previously conditioned for a 24-h period with 20 adults of L. siriboia (body length 6.2 cm, 0.3 s.d.) in a glass aquarium (20 L). Thereafter, the shrimps were removed; the conditioned water was sieved (100-mm mesh size) and immediately used for rearing of megalopae. Rearing of megalopae in filtered seawater (not conditioned with shrimps) and in the presence of 200 g of sand that was homogeneously added in the bottom of the rearing recipients. The sand was collected from the upper 3 cm of substratum surface in the habitat where the conspecific population lives. Megalopae were reared in filtered seawater and in the presence of 200 g of a natural mixing of mud and sand (referred here as muddy sand). The substratum was homogeneously added in the bottom of each rearing recipient. The muddy sand was collected from the upper 3 cm of substratum surface in the parental adult habitat. Rearing of megalopae in ACSW plus MS. Rearing in pure filtered seawater without any external cues (substratum or substances from conspecific adult shrimps).

2. Sand substratum (S)

3. Muddy-sand substratum (MS) 4. ACSW þ MS 5. Control (C)

Marine and Freshwater Research

respective data were performed following standard techniques described by Sokal and Rohlf (1995). The percentage of settled and metamorphosed larvae were analysed by means of contingency tables (rows  columns) followed by Chi-Square test. For DTTM data, normality and homogeneity of variance were checked a priori through the Kolmogorov–Smirnov test and Levene test respectively. Because data did not show the prerequisites for parametrical statistics, despite numerous transformations, the non-parametric one-way ANOVA (Kruskal– Wallis H-test) was employed for the analyses. Multiple a posteriori comparisons were performed using the Dunn test for dataset of different sample sizes or Mann–Whitney U-test to identify pair-wise differences between the respective treatments and also with the control group. Significant differences in the average density of larval and post-larval burrows among the respective treatments containing substratum (S, MS and ACSW þ MS) were also tested through the Kruskal–Wallis H-test. The critical level (a) to reject the null hypothesis was fixed at 0.05. Differences were then considered significant when P , 0.05. Data were presented as average values  standard deviation (s.d.). Results Larval settlement behaviour Settlement of ghost shrimp, Lepidophthalmus siriboia, megalopae was significantly induced when substrata (e.g. sand and muddy sand) were available in the culture media (Treatments S, MS and ACSW þ MS; Fig. 1). Furthermore, burrow constructions (1.6 burrows cm2, 0.6; pooled data from S, MS and ACSW þ MS; no significant difference was found among treatments; Kruskal–Wallis H ¼ 1.7, n ¼ 1037, d.f. ¼ 2, P ¼ 0.4374) by megalopae were also consistently observed throughout the period of rearing experiment. In Treatments S, MS and ACSW þ MS, the presence of megalopae in the culture media was rarely recorded. Larvae were observed only when a

100

a

a

80 60 40 20

C

AC

SW

⫹

M

S

M S

S

SW

0 AC

adult shrimps of L. siriboia were used (n ¼ 60 individuals). The specimens used for seawater conditioning were released back to their respective habitat of origin. The density of adult shrimps used at each seawater renewal in ACSW and ACSW þ MS (see Table 1) was chosen on the basis of the fact that the magnitude of stimulatory effects of conspecific cues on the induction of larval metamorphosis in decapod crustaceans is dose-dependent and proportional to the weight and density of the organisms (e.g. Fitzgerald et al. 1998; Andrews et al. 2001; Kopin et al. 2001; O’Connor 2005; Anderson et al. 2010). The respective treatments, including the control group, were carefully conducted to avoid contamination. In all treatments, megalopae were monitored daily for mortality, settlement and metamorphosis to JI stage. The day of moulting to megalopa was defined as Day 0 for determination of megalopal age and developmental time to metamorphosis (DTTM). In the treatments with substratum (S, MS and ACSW þ MS), the location of the megalopal exuvia after moulting to JI stage was recorded (e.g. on top or within substratum). Larval settlement was determined by the presence of burrows in the provided substratum (e.g. sand, muddy sand) and absence of larvae in the culture media as well. Metamorphosis to JI stage was recorded by the presence of megalopal exuvia. When it was not possible to find the respective exuviae, the specimens (JI) were identified through morphological inspections with a stereomicroscope (ZEISS), following descriptions given by Abrunhosa et al. (2005). The DTTM was defined as the period between the day of moulting to megalopa (¼Day 0) and the respective day when larvae moulted to JI stage. Treatments with different types of substratum (S and MS) were performed because adults and juveniles are typically found in environments containing exclusively sand and muddy sand in the Caete´ estuary. Thus, these environmental factors could be a good indicator of a suitable habitat for definitive settlement in the benthic habitat. The experimental and control treatments were conducted until the last megalopae had either died or metamorphosed to juvenile shrimp. However, to compare the burrowing and swimming behaviour between the megalopa and JI stages, newly metamorphosed juveniles were individually reared in the presence (Treatments S, MS and ACSW þ MS) and absence (ACSW, C) of substrata until moulting to JII stage. The specimens in JI stage were reared at the same conditions as used for rearing megalopae (see above). The average density of larval and juvenile (JI) burrows (burrows cm2) in the respective treatments was obtained daily for each rearing recipient (initial n ¼ 50 individuals). The counting of burrows was performed every day because they were destroyed during the search of the exuviae and buried specimens. Burrows belonging to megalopae and early juveniles were easily observable in the surface of substrata. After the end of the experiment, the juveniles (JII) were released in the habitat where the conspecific population lives.

K. L. de Noronha Campos et al.

Larval settlement (%)

D

Statistical analysis The effects of the different experimental conditions were primarily analysed comparing the percentage of settled and metamorphosed specimens, and average DTTM (days) of the megalopal stage of L. siriboia between the respective treatments and control group. All statistical analyses of the

Treatments Fig. 1. Settlement (%) of the burrowing ghost shrimp (Lepidophthalmus siriboia) megalopae in the experimental and control treatments. See Table 1 for abbreviations and descriptions. Initial n ¼ 50 megalopae individually reared per treatment. Same letters above bars indicate statistically homogeneous groups (P . 0.05).

Settlement and metamorphosis of ghost shrimp larvae

Marine and Freshwater Research

they were in feeding activity. After the feeding period, megalopae excavated new burrows or returned to the previously constructed burrows. After metamorphosis, specimens in the first juvenile stage (JI) also showed a cryptic life style and burrowing behaviour. For JI stage, the average density of burrows was 2.2 burrows cm2, 0.7 (pooled data from the Treatments S, MS and ACSW þ MS; no significant difference was detected among treatments; Kruskal–Wallis H ¼ 1.3, n ¼ 1637, d.f. ¼ 2, P ¼ 0.5227). In the treatments with adult-conditioned seawater (ACSW) and filtered seawater (Control C) both without substratum, megalopae and juveniles showed a high frequency of swimming activity and, in rare occasions, the specimens were observed sitting on the bottom of the rearing vials. Larval metamorphosis to juvenile ghost shrimp All the different experimental conditions of the respective treatments resulted in high moulting rates ($96%) to JI stage of L. siriboia (Fig. 2a). However, no significant (P . 0.05) difference was found between the experimental treatments and the

Larval metamorphosis (%)

(a) 100

a

a

a

a

a

a

a

80

60

40

20

0

(b) 10 a

a

b 6

4

2

C

AC SW

⫹

M

S

M S

S

0 AC SW

Control group C (filtered seawater) where 100% of the megalopae successfully metamorphosed to JI in the absence of chemical substances emitted by the conspecific adult shrimps (adult-conditioned seawater) or benthic substrata (e.g. sand and muddy sand; Fig. 2a). When larvae were reared in the presence of sand and muddy sand (S, MS and ACSW þ MS), 95.3% (1.5) of the megalopal exuviae resulting from the metamorphic process were found within the larval burrows constructed in the respective substrata. The average DTTM of L. siriboia megalopae did not show significant differences among the respective experimental treatments (Kruskal–Wallis H ¼ 6.4, n ¼ 198, d.f. ¼ 3, P ¼ 0.0923; Fig. 2b). However, pair-wise comparisons through post hoc tests revealed that the average DTTM differed significantly (P , 0.001) between the respective experimental treatments and the Control group C (Fig. 2b). Megalopae developed significantly faster (P , 0.01) when reared without cues in the filtered seawater Control C (5.7 days, 0.9) than in the experimental treatments containing adult-conditioned seawater or substrata (averages ranging from 6.8 to 7.3 days; Fig. 2b). The developmental time of L. siriboia megalopae through metamorphosis varied from 4 to 9 days (Fig. 3). In three of the four experimental treatments (ACSW, S and MS), the first events of moulting from megalopa to JI stage (8–12%) were recorded by Day 5 (Fig. 3). In such treatments, the highest percentage of larvae undergoing metamorphosis to juvenile (38–44%) occurred by Day 6 (Fig. 3). In ACSW þ MS, the first juveniles (30%) only appeared on Day 6 (Fig. 3). In all experimental treatments, the last specimens underwent metamorphosis by Day 9 of megalopal rearing (Fig. 3). In contrast to the treatments above, in the Control group C, the first juveniles appeared by Day 4 and the last by Day 8 (Fig. 3). In this treatment, the highest daily percentages of successfully metamorphosed larvae were recorded by Days 5 (46%) and 6 (36%) of megalopal development (Fig. 3). Discussion

8

DTTM (in days)

E

Treatments Fig. 2. (a) Percentage of successful metamorphosed megalopae and (b) developmental time to metamorphosis (DTTM, days, average  s.d.) of the burrowing ghost shrimp (Lepidophthalmus siriboia) in the experimental and control treatments. See Table 1 for abbreviations and descriptions. Initial n ¼ 50 megalopae individually reared per treatment. Different letters above bars indicate significant (P , 0.05) differences between average values after pair-wise comparisons using the Dunn test or Mann–Whitney U-test.

Megalopal settlement and metamorphosis of many marine and estuarine decapod crustaceans are triggered in response to natural physicochemical or biological stimuli characteristics of the specific habitat where the conspecific juveniles and adults are found (reviewed by Anger 2001; Forward et al. 2001; Gebauer et al. 2003). In the present laboratory study, over 90% of the burrowing ghost shrimp, Lepidophthalmus siriboia, megalopae successfully metamorphosed to the first juvenile stage when reared in seawater that was previously conditioned with conspecific adult shrimps (ACSW) and when they were kept in contact with sand (S) and muddy-sand substrata (MS). Furthermore, all megalopae also underwent metamorphosis to the juvenile stage in filtered seawater Control (C) and, therefore, in the absence of such cues. These findings demonstrated that the induction of larval metamorphosis of L. siriboia may occur irrespective of the presence or type of exogenous stimuli associated with substrata originating from the parental benthic habitat or chemical substances (i.e. ‘odours’) produced by the conspecific adult shrimps. Similar results were also reported for megalopae of two other callianassid shrimps, e.g. Callichirus major and C. islagrande, when reared without conspecific adult odours or sand substratum (Strasser and

F

Marine and Freshwater Research

K. L. de Noronha Campos et al.

50

50

ACSW ⫹ MS

Larval metamorphosis (%)

ACSW 40

40

30

30

20

20

10

10

0

0 4

5

6

7

8

9

4

5

6

7

8

9

50

50

S

C

40

40

30

30

20

20

10

10

0

0 4

5

6

7

8

9

4

5

6

7

8

9

50

Larval metamorphosis (%)

MS 40

30

20

10

0 4

5

6

7

8

9

Days of megalopal culture Fig. 3. Frequency of larval metamorphosis to first juvenile stage of the burrowing ghost shrimp (Lepidophthalmus siriboia) during the days of megalopal rearing in the experimental and control treatments. See Table 1 for abbreviations and descriptions. Initial n ¼ 50 megalopae individually reared per treatment.

Felder 1998, 1999a, 1999b). In some brachyuran crab species, e.g. Callinectes sapidus (see Forward et al. 1994), Carcinus maenas (see Zeng et al. 1997) and Menippe mercenaria (see Krimsky and Epifanio 2008), the moulting to juvenile was not influenced by the presence of conspecific adult odours. In contrast to the species above, several other decapod crustaceans exhibit an increased larval mortality in the absence of suitable habitat cues (see review in Forward et al. 2001; Gebauer et al. 2003, and papers cited therein). However, for callianassid

species, it appears that chemical odours are not recognised by the megalopae or, probably, the conspecific adults do not produce them. In contrast, megalopae could identify conspecific odours released by the adults, but these cues do not seem to play an important role in triggering the larval metamorphosis. Such hypothesis is strengthened by the fact that no significant difference was found between the moulting rates of L. siriboia recorded in the respective treatments ACSW, ACSW þ MS and the Control group C.

Settlement and metamorphosis of ghost shrimp larvae

Although metamorphosis of L. siriboia megalopae was not dependent on external cues, their settlement behaviour and burrowing, by contrast, were significantly induced by sand and muddy-sand substrata in our cultures (S, MS and ACSW þ MS). Furthermore, 95.3% (1.5) of the megalopal exuviae resulting from the metamorphosis to juvenile were consistently found within their burrows. The same was also observed in megalopae of C. major and C. islagrande when reared with sand substratum (Strasser and Felder 1998, 1999a, 1999b). This larval behaviour could be explained by the fact that callianassid ghost shrimps are extremely dependent on their burrows and galleries for protection, reproduction and feeding (Griffis and Suchanek 1991) and, hence, their cryptic life style and burrowing behaviour are transmitted to offspring and activated early in ontogeny when larvae reach the megalopal stage. This would explain why callianassid megalopae are strongly attracted and stimulated to settle in response to substrata from the estuarine environment. Also, the cryptic larval behaviour should be adaptively important to reduce the risk of predation essentially during the metamorphosis to juvenile, a period in which decapod larvae become more susceptible to pelagic and benthic predators. In addition, the burrowing behaviour seems to be important to decrease the energy loss caused by swimming as well as to avoid the larval re-exportation from the estuaries to offshore waters by ebb tide currents. Stimulation by natural settlement cues could be extremely important during recruitment to the parental estuarine habitat. Recently, Oliveira et al. (2012) suggested that L. siriboia larvae are transported downstream for completing their ontogenesis in high salinities found in fully marine waters. When megalopae migrate back upstream to the estuarine system, the settlementstimulating cues could aid during the location of an appropriated microhabitat for the early post-metamorphic development and growth of young benthic recruits. However, the present finding that high numbers of megalopae moulted to juvenile when reared without cues (Control C) suggests that larval metamorphosis of L. siriboia may also occur in the planktonic environment before settlement in the benthic habitat. In the laboratory, we observed that freshly moulted juveniles exhibit an active swimming behaviour similar to the conspecific megalopae. These findings implicate that first juveniles could also be an ontogenetic stage of recruitment and settlement of this species. Therefore, our results suggest that L. siriboia may exhibit two different strategies of recruitment which could be determined by the (1) spatial extent and magnitude of the larval transport towards adjacent coastal or fully marine waters, which are influenced by the local hydrodynamic and climatic conditions (e.g. surface current speed during ebb tides, coastal currents, winds), (2) duration of the larval (zoeal) development period to megalopa, and (3) presence or absence of natural settlement inducers (e.g. sand and muddy-sand substrata) from the parental adult habitat (Fig. 4). Similarly to the moulting rates, the DTTM of L. siriboia megalopae did not differ among the experimental treatments containing the natural cues tested. However, pair-wise comparisons showed that megalopae developed significantly faster in the Control C than in the remaining treatments. In contrast to L. siriboia, larvae of many other decapod species delay their

Marine and Freshwater Research

G

metamorphosis when suitable habitat cues or conspecific adult odours are absent (e.g. Chasmagnathus (Neohelice) granulata (see Gebauer et al. 1998), Sesarma curacaoense (see Gebauer et al. 2002), Hemigrapsus sanguineus (see Kopin et al. 2001; Steinberg et al. 2007, 2008; O’Connor 2008), Uca pugnax (see O’Connor and Gregg 1998; O’Connor and Van 2006), Ucides cordatus (see Diele and Simith 2007; Simith and Diele 2008b)). Here, it remains unclear why L. siriboia megalopae had a fast DTTM in filtered seawater devoid of cues; however, this result again suggests that freshly moulted juveniles are also able to reimmigrate to the parental estuaries after metamorphosing in the planktonic environment. It could also be argued that burrowing activity by the megalopae in the presence of substratum (S, MS and ACSW þ MS) may have caused an energy expenditure, resulting in an increased developmental time of this stage and, thus, delaying the metamorphosis to juvenile. However, this possibility could be excluded by the fact that megalopae reared in ACSW (without substratum) had a DTTM similar to those of specimens cultured in Treatments S, MS and ACSW þ MS. The same was also observed in other species such as C. (Neohelice) granulata (see Gebauer et al. 1998) and Panopeus herbstii (see Rodriguez and Epifanio 2000). In our experimental results, no significant difference was found in the moulting rates and DTTM of L. siriboia among Treatments ACSW, MS and ACSW þ MS, indicating that the combination of adult-conditioned seawater and muddy sand do not have a synergistic effect on the larval stimulation. In other decapod crustaceans, by contrast, the survival rate was enhanced and development of the megalopal stage was accelerated when they were exposed to substrata associated with conspecific adult odours or colonised by biofilms (e.g. U. pugilator (see Christy 1989; O’Connor 1991), C. (Neohelice) granulata (see Gebauer et al. 1998), P. herbstii (see Weber and Epifanio 1996; Rodriguez and Epifanio 2000), U. pugnax (see O’Connor and Van 2006), U. cordatus (see Diele and Simith 2007), M. mercenaria (see Krimsky and Epifanio 2008), H. sanguineus (see Steinberg et al. 2008; Anderson and Epifanio 2009)). According to some authors, the combination of multiple environmental cues has a strong influence on the larval ‘decision’ for an appropriated habitat for their settlement and subsequent juvenile development in the benthic environment (see Anger 2001, 2006, and papers cited therein). In L. siriboia megalopae, the recognition of a suitable habitat for definitive settlement seems to be more related to substrata typical for the estuarine benthic habitat than to other types of environmental factors involved. In summary, our experimental study demonstrated that mediation of megalopal metamorphosis of the burrowing ghost shrimp, L. siriboia, may occur without external cues associated with the parental estuarine habitat or conspecific adult shrimps. However, their larval settlement and burrowing behaviour were induced in response to sand and muddy-sand substrata when available in the culture, indicating that this species has already a cryptic life style during the megalopal stage. The finding that megalopae moulted to juvenile without cues suggests that L. siriboia may have two strategies or developmental stages of recruitment which could be selected by the (1) extent of the larval dispersal, (2) duration of zoeal development, and (3) presence of natural settlement cues. In addition, the independence of metamorphosis-stimulating cues and the observed

H

Marine and Freshwater Research

K. L. de Noronha Campos et al.

(I) Larval dispersal near coastal marine waters

(I) Larval dispersal to fully marine waters

(II) Larval development period synchronised with re-

(II) Fast larval development in offshore waters before

immigrations of the megalopae to the estuarine system

returning of the megalopae to the estuaries

(Ill) Presence of natural settlement cues from adult

(III) Absence of natural settlement cues from adult

habitat

habitat

Larval settlement in the benthic environment of the

Larval metamorphosis to juvenile occurs in the

estuaries followed by metamorphosis to juvenile within

planktonic environment before settlement of the

the megalopal burrows

megalopae in the benthic habitat of the estuaries

Megalopa as recruitment and

Juvenile as recruitment and

settlement stage

settlement stage

Fig. 4. Hypothetical strategies and conditions for selecting the recruitment and settlement stage of the burrowing ghost shrimp (Lepidophthalmus siriboia).

larval attractiveness by benthic substrata should be ecologically important for colonisation of new estuarine areas as well as for recovery and maintenance of viable populations in disturbed habitats where callianassid ghost shrimps are intensively harvested (e.g. Borzone and Souza 1996; Botter-Carvalho et al. 2002, 2007; Souza and Borzone 2003; Skilleter et al. 2005). Acknowledgements This work was supported by the ‘Programa Institucional de Bolsas de Iniciac¸a˜o Cientı´fica’ (PIBIC) and the ‘Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo´gico’ (CNPq). The authors thank the three anonymous reviewers for their helpful comments.

References Abrunhosa, F. A., Pires, M. A., Lima, J. F., and Coelho-Filho, P. A. (2005). Larval development of Lepidophthalmus siriboia Felder and Rodrigues, 1993 (Decapoda: Thalassinidea) from the Amazon region, reared in the laboratory. Acta Amazonica 35, 77–84. doi:10.1590/S004459672005000100012 Abrunhosa, F. A., Simith, D. J. B., Palmeira, C. A. M., and Arruda, D. C. B. (2008). Lecithotrophic behaviour in zoea and megalopa larvae of the ghost shrimp Lepidophthalmus siriboia Felder and Rodrigues, 1993 (Decapoda: Callianassidae). Annals of the Brazilian Academy of Sciences 80, 639–646. doi:10.1590/S0001-37652008000400005

Anderson, J. A., and Epifanio, C. E. (2009). Induction of metamorphosis in the Asian shore crab Hemigrapsus sanguineus: characterization of the cue associated with biofilm from adult habitat. Journal of Experimental Marine Biology and Ecology 382, 34–39. doi:10.1016/J.JEMBE.2009. 10.006 Anderson, J. A., Valentine, M., and Epifanio, C. E. (2010). Characterization of the conspecific metamorphic cue for Hemigrapsus sanguineus (De Haan). Journal of Experimental Marine Biology and Ecology 382, 139–144. doi:10.1016/J.JEMBE.2009.10.005 Andrews, W. R., Targett, N. M., and Epifanio, C. E. (2001). Isolation and characterization of the metamorphic inducers of the common mud crab, Panopeus herbstii. Journal of Experimental Marine Biology and Ecology 261, 121–134. doi:10.1016/S0022-0981(01)00268-4 Anger, K. (2001). ‘The Biology of Decapod Crustacean Larvae. Crustacean Issues. Vol. 14.’ (A. A. Balkema: Lisse, Netherlands.) Anger, K. (2006). Contributions of larval biology to crustacean research: a review. Invertebrate Reproduction & Development 49, 175–205. doi:10.1080/07924259.2006.9652207 Berkenbusch, K., and Rowden, A. A. (1999). Factors influencing sediment turnover by the burrowing ghost shrimp Callianassa filholi (Decapoda: Thalassinidea). Journal of Experimental Marine Biology and Ecology 238, 283–292. doi:10.1016/S0022-0981(99)00019-2 Borzone, C. A., and Souza, J. R. B. (1996). A extrac¸a˜o de corrupto Callichirus major (Decapoda: Callianassidae) para uso como iscas em praias do litoral do Parana´: caracterı´sticas da pesca. Nerı´tica 10, 67–79. Botter-Carvalho, M. L., Santos, P. J. P., and Carvalho, P. V. V. C. (2002). Spatial distribution of Callichirus major (Say 1818) (Decapoda,

Settlement and metamorphosis of ghost shrimp larvae

Callianassidae) on a sandy beach, Piedade, Pernambuco, Brazil. Nauplius 10, 97–109. Botter-Carvalho, M. L., Santos, P. J. P., and Carvalho, P. V. V. C. (2007). Population dynamics of Callichirus major (Say, 1818) (Crustacea, Thalassinidea) on a beach in northeastern Brazil. Estuarine, Coastal and Shelf Science 71, 508–516. doi:10.1016/J.ECSS.2006.09.001 Chia, F. S., and Rice, M. E. (1978). ‘Settlement and Metamorphosis of Marine Invertebrate Larvae.’ (Elsevier: North-Holland, NY.) Christy, J. H. (1989). Rapid development of megalopae of the fiddler crab Uca pugilator reared over sediment: Implications for models of larval recruitment. Marine Ecology Progress Series 57, 259–265. doi:10.3354/ MEPS057259 Contessa, L., and Bird, F. L. (2004). The impact of bait-pumping on populations of the ghost shrimp Trypaea australiensis Dana (Decapoda: Callianassidae) and the sediment environment. Journal of Experimental Marine Biology and Ecology 304, 75–97. doi:10.1016/J.JEMBE.2003. 11.021 Diele, K., and Simith, D. J. B. (2006). Salinity tolerance of northern Brazilian mangrove crab larvae, Ucides cordatus (Ocypodidae): Necessity for larval export? Estuarine, Coastal and Shelf Science 68, 600–608. doi:10.1016/J.ECSS.2006.03.012 Diele, K., and Simith, D. J. B. (2007). Effects of substrata and conspecific odour on the metamorphosis of mangrove crab megalopae, Ucides cordatus (Ocypodidae). Journal of Experimental Marine Biology and Ecology 348, 174–182. doi:10.1016/J.JEMBE.2007.04.008 Felder, D. L. (2001). Diversity and ecological significance of deep-burrowing macrocrustaceans in coastal tropical waters of the Americas (Decapoda: Thalassinidea). Interciencia 26, 440–449. Felder, D. L., and Rodrigues, S. A. (1993). Reexamination of the ghost shrimp Lepidophthalmus louisianensis (Schmitt, 1935) from the northern Gulf of Mexico and comparison to L. siriboia, a new species, from Brazil (Decapoda: Thalassinidea: Callianassidae). Journal of Crustacean Biology 13, 357–376. doi:10.2307/1548981 Felder, D. L., and Staton, J. L. (2000). Lepidophthalmus manningi, a new ghost shrimp from the southwestern Gulf of Mexico (Decapoda: Thalassinidea: Callianassidae). Journal of Crustacean Biology 20, 157–169. Fitzgerald, T. P., Forward, R. B., and Tankersley, R. A. (1998). Metamorphosis of the estuarine crab Rhithropanopeus harrisii: effect of water type and adult odor. Marine Ecology Progress Series 165, 217–223. doi:10.3354/MEPS165217 Forward, R. B., Frankel, D. A. Z., and Rittschof, D. (1994). Molting of megalopa from the blue crab Callinectes sapidus: effects of offshore and estuarine cues. Marine Ecology Progress Series 113, 55–59. doi:10.3354/MEPS113055 Forward, R. B., Tankersley, R. A., and Rittschof, D. (2001). Cues for metamorphosis of brachyuran crabs: an overview. American Zoologist 41, 1108–1122. doi:10.1668/0003-1569(2001)041[1108:CFMOBC]2.0. CO;2 Gebauer, P. I., Walter, I., and Anger, K. (1998). Effects of substratum and conspecific adults on the metamorphosis of Chasmagnathus granulata (Dana) (Decapoda: Grapsidae) megalopae. Journal of Experimental Marine Biology and Ecology 223, 185–198. doi:10.1016/S0022-0981 (97)00159-7 Gebauer, P. I., Paschke, K., and Anger, K. (1999). Costs of delayed metamorphosis: reduced growth and survival early juveniles of an estuarine grapsid crab, Chasmagnathus granulata. Journal of Experimental Marine Biology and Ecology 238, 271–281. doi:10.1016/S00220981(98)00219-6 Gebauer, P. I., Paschke, K., and Anger, K. (2002). Metamorphosis in a semiterrestrial crab, Sesarma curacaoense: intra- and interespecific settlement cues from adult odors. Journal of Experimental Marine Biology and Ecology 268, 1–12. doi:10.1016/S0022-0981(01)00360-4 Gebauer, P. I., Paschke, K., and Anger, K. (2003). Delayed metamorphosis in decapod crustaceans: evidence and consequences. Revista Chilena de Historia Natural 76, 169–175. doi:10.4067/S0716-078X2003000200004

Marine and Freshwater Research

I

Griffis, R. B., and Suchanek, T. H. (1991). A model of burrow architecture and trophic modes in thalassinidean shrimp (Decapoda: Thalassinidea). Marine Ecology Progress Series 79, 171–183. doi:10.3354/MEPS079171 Grosberg, R. K., and Levitan, D. R. (1992). For adults only? Supply-side ecology and the history of the larval biology. Trends in Ecology & Evolution 7, 130–133. doi:10.1016/0169-5347(92)90148-5 Hadfield, M. G., and Paul, V. J. (2001). Natural chemical cues for settlement and metamorphosis of marine-invertebrate larvae. In ‘Marine Chemical Ecology’. (Eds J. B. McClintock and B. J. Baker.) pp. 431–460. (CRC Press: Boca Raton, FL, USA.) Heyland, A., and Moroz, L. L. (2006). Signaling mechanisms underlying metamorphic transitions in animals. Integrative and Comparative Biology 46, 743–759. doi:10.1093/ICB/ICL023 Hodgson, A. N., Allanson, B. R., and Cretchley, R. (2000). The exploitation of Upogebia africana (Crustacea: Thalassinidae) for bait in the Knysna Estuary. Transactions of the Royal Society of South Africa 55, 197–204. doi:10.1080/00359190009520444 Kopin, C. Y., Epifanio, C. E., Nelson, S., and Stratton, M. (2001). Effects of chemical cues on metamorphosis of the Asian shore crab Hemigrapsus sanguineus, an invasive species on the Atlantic Coast of North America. Journal of Experimental Marine Biology and Ecology 265, 141–151. doi:10.1016/S0022-0981(01)00326-4 Krimsky, L. S., and Epifanio, C. E. (2008). Multiple cues from multiple habitats: effect on metamorphosis of the Florida stone crab, Menippe mercenaria. Journal of Experimental Marine Biology and Ecology 358, 178–184. doi:10.1016/J.JEMBE.2008.02.010 Melo, G. A. S. (1999). ‘Manual de Identificac¸a˜o dos Crustacea Decapoda do Litoral Brasileiro: Anomura, Thalassinidea, Palinuridea, Astacidea.’ (Editora Pleˆiade/Fadesp: Sa˜o Paulo, Brazil.) Morgan, S. G. (1995). Life and death in the plankton: larval mortality and adaptation. In ‘Ecology of Marine Invertebrate Larvae’. (Ed. L. R. McEdward.) pp. 279–321. (CRC Press: Boca Raton, FL, USA.) New, M. B. (2002). ‘Farming freshwater prawns: a manual for the culture of the giant freshwater prawn (Macrobrachium rosenbergii). FAO Fisheries Technical Paper 428.’ (FAO: Rome, Italy.) O’Connor, N. J. (1991). Flexibility in timing of the metamorphic molt by fiddler crab megalopae Uca puligator. Marine Ecology Progress Series 68, 243–247. doi:10.3354/MEPS068243 O’Connor, N. J. (2005). Influence of extracts of adult crabs on molting of fiddler crab megalopae (Uca pugnax). Marine Biology 146, 753–759. doi:10.1007/S00227-004-1472-X O’Connor, N. J. (2008). Stimulation of molting in megalopae of the Asian shore crab Hemigrapsus sanguineus: physical and chemical cues. Marine Ecology Progress Series 282, 229–236. O’Connor, N. J., and Gregg, A. S. (1998). Influence of potential habitat cues on duration of megalopal stage of the fiddler crab Uca pugnax. Journal of Experimental Marine Biology and Ecology 18, 700–709. O’Connor, N. J., and Van, B. T. (2006). Adult fiddler crabs Uca pugnax (Smith) enhance sediment-associated cues for molting of conspecific megalopae. Journal of Experimental Marine Biology and Ecology 335, 123–130. doi:10.1016/J.JEMBE.2006.03.012 Oliveira, D. B., Silva, D. C., and Martinelli, J. M. (2012). Density of larval and adult forms of the burrowing crustaceans Lepidophthalmus siriboia (Callianassidae) and Upogebia vasquezi (Upogebiidae) in an Amazon estuary, northern Brazil. Journal of the Marine Biological Association of the United Kingdom 92, 295–303. doi:10.1017/S002531541100097X Pawlik, J. R. (1992). Chemical ecology of the settlement of benthic marine invertebrates. Oceanography and Marine Biology – an Annual Review 30, 273–335. Pechenik, J. A. (1990). Delayed metamorphosis by larvae of benthic marine invertebrates: does it occur? Is there a price to pay? Ophelia 32, 63–94. doi:10.1080/00785236.1990.10422025 Pechenik, J. A. (2006). Larval experience and latent effects: metamorphosis is not a new beginning. Integrative and Comparative Biology 46, 323–333. doi:10.1093/ICB/ICJ028

J

Marine and Freshwater Research

K. L. de Noronha Campos et al.

Pechenik, J. A., Wendt, D. E., and Jarrett, J. N. (1998). Metamorphosis is not a new beginning: larval experience influences juvenile performance. Bioscience 48, 901–910. doi:10.2307/1313294 Rodrigues, S. A., and Shimizu, R. M. (1998). Malacostraca-Eucarida. Thalassinidea. In ‘Catalogue of Crustacea of Brazil’. (Ed. P. S. Young.) pp. 279–385. (Museu Nacional: Rio de Janeiro, Brazil.) Rodriguez, R. A., and Epifanio, C. E. (2000). Multiple cues for induction of metamorphosis in larvae of the common mud crab Panopeus herbstii. Marine Ecology Progress Series 195, 221–229. doi:10.3354/ MEPS195221 Rodrı´guez, S. R., Ojeda, F. P., and Inestrosa, N. C. (1993). Settlement of benthic marine invertebrates. Marine Ecology Progress Series 97, 193–207. doi:10.3354/MEPS097193 Simith, D. J. B., and Diele, K. (2008a). O efeito da salinidade no desenvolvimento larval do caranguejo-uc¸a´, Ucides cordatus (Linnaeus, 1763) (Decapoda: Ocypodidae) no Norte do Brasil. Acta Amazonica 38, 345–350. doi:10.1590/S0044-59672008000200019 Simith, D. J. B., and Diele, K. (2008b). Metamorphosis of mangrove crab megalopae, Ucides cordatus (Ocypodidae): effects of interspecific versus intraspecific settlement cues. Journal of Experimental Marine Biology and Ecology 362, 101–107. doi:10.1016/J.JEMBE.2008.06.005 Simith, D. J. B., Abrunhosa, F. A., and Diele, K. (2010). Influence of natural settlement cues on the metamorphosis of fiddler crab megalopae, Uca vocator (Decapoda: Ocypodidae). Annals of the Brazilian Academy of Sciences 82, 313–321. doi:10.1590/S0001-37652010000200007 Simith, D. J. B., Souza, A. S., Maciel, C. R., Abrunhosa, F. A., and Diele, K. (2012). Influence of salinity on the larval development of the fiddler crab Uca vocator (Ocypodidae) as an indicator of ontogenetic migration towards offshore waters. Helgoland Marine Research 66, 77–85. doi:10.1007/S10152-011-0249-0 Simith, D. J. B., Diele, K., and Abrunhosa, F. A. (2013). Carry-over effects of delayed larval metamorphosis on early juvenile performance in the mangrove crab Ucides cordatus (Ucididae). Journal of Experimental Marine Biology and Ecology 440, 61–68. doi:10.1016/J.JEMBE.2012. 11.017 Simith, D. J. B., Pires, M. A., Abrunhosa, F. A., Maciel, C. R., and Diele, K. (2014). Is larval dispersal a necessity for decapod crabs from the Amazon mangroves? Response of Uca rapax zoeae to different salinities and comparison with sympatric species. Journal of Experimental Marine Biology and Ecology 457, 22–30. doi:10.1016/J.JEMBE.2014. 03.021 Skilleter, G. A., Zharikov, Y., Cameron, B., and McPhee, D. P. (2005). Effects of harvesting callianassid (ghost) shrimps on subtropical benthic communities. Journal of Experimental Marine Biology and Ecology 320, 133–158. doi:10.1016/J.JEMBE.2004.12.033 Sokal, R. R., and Rohlf, F. J. (1995). ‘Biometry: the Principles and Practice of Statistics in Biological Research’, 3rd edn. (W. H. Freeman and Company: New York.) Souza, J. R. B., and Borzone, C. A. (2003). A extrac¸a˜o do corrupto, Callichirus major (Say) (Crustacea, Thalassinidea), para uso como isca em praias do litoral do Parana´: as populac¸o˜es exploradas. Revista Brasileira de Zoologia 20, 625–630. doi:10.1590/S010181752003000400011 Steinberg, M. K., Epifanio, C. E., and Andon, A. (2007). A highly specific chemical cue for the metamorphosis of the Asian shore crab, Hemigrapsus sanguineus. Journal of Experimental Marine Biology and Ecology 347, 1–7. doi:10.1016/J.JEMBE.2007.02.005

Steinberg, M. K., Krimsky, L. S., and Epifanio, C. E. (2008). Induction of metamorphosis in the Asian shore crab Hemigrapsus sanguineus: effects of biofilms and substratum texture. Estuaries and Coasts 31, 738–744. doi:10.1007/S12237-008-9063-6 Strasser, K. M., and Felder, D. L. (1998). Settlement cues in successive developmental stages of the ghost shrimps Callichirus major and C. islagrande (Crustacea: Decapoda: Thalassinidea). Marine Biology 132, 599–610. doi:10.1007/S002270050425 Strasser, K. M., and Felder, D. L. (1999a). Settlement cues in an Atlantic coast population of the ghost shrimp Callichirus major (Crustacea: Decapoda: Thalassinidea). Marine Ecology Progress Series 183, 217–225. doi:10.3354/MEPS183217 Strasser, K. M., and Felder, D. L. (1999b). Sand as a stimulus for settlement in the ghost shrimp Callichirus major (Say) and C. islagrande (Schmitt) (Crustacea: Decapoda: Thalassinidea). Journal of Experimental Marine Biology and Ecology 239, 211–222. doi:10.1016/S0022-0981(99) 00036-2 Suchanek, T. H. (1983). Control of seagrass communities and sediment distribution by Callianassa (Crustacea, Thalassinidea) bioturbation. Journal of Marine Research 41, 281–298. doi:10.1357/ 002224083788520216 Tamaki, A., Ikebe, K., Muramatsu, K., and Ingole, B. (1992). Utilization of adult burrows by juveniles of the ghost shrimp, Callianassa japonica Ortmann: evidence from resin casts of burrows. Researches on Crustacea 21, 113–120. Timmons, M. B., Ebeling, J. M., Wheaton, F. W., Summerfelt, S. T., and Vinci, B. J. (2002). ‘Recirculating Aquaculture Systems’, 2nd edn. Northeastern Regional Aquaculture Center Publication 01-002. (Cayuga Aqua Ventures: Ithaca, NY.) Underwood, A. J., and Fairweather, P. G. (1989). Supply-side ecology and benthic marine assemblages. Trends in Ecology & Evolution 4, 16–20. doi:10.1016/0169-5347(89)90008-6 Valenti, W. C., Mallansen, M., and Silva, C. A. (1998). Larvicultura em ´ gua Doce: Tecnologia sistema fechado dinaˆmico. In ‘Carcinicultura de A para a Produc¸a˜o de Camaro˜es’. (Ed. W. C. Valenti.) pp. 112–139. (Fundac¸a˜o de Amparo a` Pesquisa do Estado de Sa˜o Paulo – FAPESP, Sa˜o Paulo e Instituto do Meio Ambiente e dos Recursos Naturais Renova´veis – IBAMA: Brası´lia, Brazil.) Valenti, W. C., Mallansen, M., and Barros, H. P. (2009). Sistema de recirculac¸a˜o e rotina de manejo para larvicultura de camaro˜es de a´gua doce Macrobrachium rosenbergii em pequena escala. Boletin do Instituto de Pesca 35, 141–151. Valenti, W. C., Daniels, W. H., New, M. B., and Correia, E. S. (2010). Hatchery systems and management. In ‘Freshwater Prawns: Biology and Farming’. (Eds M. B. New, W. C. Valenti, J. H. Tidwell, L. R. D’Abramo and M. N. Kutty.) pp. 55–85. (Wiley-Blackwell: Oxford, UK.) Webb, A. P., and Eyre, B. D. (2004). Effect of natural populations of burrowing thalassinidean shrimp on the sediment irrigation, benthic metabolism, nutrient fluxes and denitrification. Marine Ecology Progress Series 268, 205–220. doi:10.3354/MEPS268205 Weber, J. C., and Epifanio, C. E. (1996). Response of mud crab (Panopeus herbstii) megalopae to cues from adult habitat. Marine Biology 126, 655–661. doi:10.1007/BF00351332 Zeng, C., Naylor, E., and Abello, P. (1997). Endogenous control of timing of metamorphosis in megalopae of the shore crab Carcinus maenas. Marine Biology 128, 299–305. doi:10.1007/S002270050095

www.publish.csiro.au/journals/mfr