Species-specific diets and spatial variation in the feeding habits of mud crabs Scylla spp. in Thailand

Abstract

This study examined the dietary compositions of three sympatric mud crab species-Scylla olivacea, S. tranquebarica, and S. paramamosain-across six coastal provinces of Thailand, encompassing the Andaman Sea and the Gulf of Thailand. A total of 4,112 individuals, mainly S. olivacea, were collected monthly from June 2022 to June 2023, and stomach contents were analyzed volumetrically. Prey compositions, vacuity index (VI), fullness index (FI), diet breadth, and diet overlap were quantified. Fish constituted the predominant prey item for all three species, representing 56.0%, 57.8%, and 42.5% of the diet in S. olivacea, S. tranquebarica, and S. paramamosain, respectively. Secondary prey items exhibited interspecific variation: crabs for S. olivacea (15.1%), and bivalves for both S. paramamosain (22.7%) and S. tranquebarica (24.8%). Gastropods contributed significantly to the diet of S. paramamosain (9.1%). Multivariate analyses revealed distinct dietary separations between the three Scylla species. Significant site-specific variation in the diet of S. olivacea was observed between Gulf of Thailand and the Andaman Sea (P < 0.05). In contrast, no significant differences in dietary composition were detected between male and female crabs for either S. olivacea or S. paramamosain. These findings elucidate species-specific dietary preferences and the influence of habitat on the trophic ecology of these mud crab species, providing pertinent insights for aquaculture practices and sustainable resource management strategies.

Keywords:
Diet breadth; Diet overlap; Fullness index; Stomach content; Habitat influence

INTRODUCTION

Feeding ecology is a fundamental basis for understanding and explaining spatial roles of different organisms in the marine ecosystem (Blaber, 1997; Hajisamae et al., 2022; Iqbal et al., 2023; Islam et al., 2018; Soe et al., 2021; Wootton, 1998).

Crustaceans, especially crabs, play a crucial role in the food web and support nutrient cycling as scavengers (Tewfik et al., 2016; Vale et al., 2022). Mud crabs (Scylla spp.) are large portunid crabs inhabiting coastal habitats across the Indo-West Pacific region (Keenan et al., 1998; Viswanathan and Raffi, 2015) and are commercially important in both fisheries and aquaculture sectors (Fazhan et al., 2017a; Hamasaki et al., 2011; Imai et al., 2004; Le Vay, 2001; Nurdiani and Zeng, 2007). Due to their fleshy taste, status as a local delicacy, and high market demand in both domestic and international markets (Sathiadhas and Najmudeen, 2004; Waiho et al., 2018), they are widely and heavily harvested in many Asian countries (Azra and Ikhwanuddin, 2016). Although considered top benthic predators, primarily preying on slow-moving micro-invertebrates, detailed information on the food and feeding habits of some Scylla species is scarce. They have been reported as omnivorous, with diets including crustaceans, gastropods, mollusks, fish, seagrass, and mangrove plants (Alberts-Hubatsch et al., 2016; Ikhwanuddin et al., 2014; Sara et al., 2007). Scylla serrata, the widest studied species, has been found to feed on various items including sand, shell, unidentified organic matter, meat, wood remains, mollusks, gastropods, crustaceans, fish meat, fish hard parts, plant leaf fragments, Sargassum, and eelgrass (Sara et al., 2007). S. tranquebarica has been reported to feed on crustaceans, molluscan remains, fish remains, detritus, and debris (Nesakumari and Thirunavukkarasu, 2014). Recently, Soe et al. (2024) found that approximately 22% of mud crabs (Scylla spp.) ingested plastic particles. Likewise, research on other portunid crabs revealed that Portunus pelagicus consumes bivalves, gastropods, cephalopods, shrimp, crabs, polychaetes, echinoderms, fish, unidentified animal tissue, seagrass, seaweed, and digested material (Hajisamae et al., 2015). Studies on ghost crabs (Ocypode quadrata) have also identified insects, unidentified organic matter, and crustaceans as key dietary components (Vale et al., 2022).

Generally, several factors contribute to dietary variations in aquatic fauna including mud crabs. Ontogenetic dietary shifts are also evident in mud crabs, with small crabs being omnivorous (including smaller crabs and plants/scavenging), and larger crabs becoming carnivorous, feeding on benthic invertebrates (Prasad and Neelakantan, 1988; Webley, 2008). Paralleling observations in P. pelagicus, Hajisamae et al. (2015) reported that larger crabs exhibited higher feeding intensity. Diel feeding patterns are another factor affecting the feeding behavior of crabs. It is reported that S. serrata exhibits nocturnal feeding behavior by being active at night and remaining buried during the day (Hill, 1979). Moreover, the environment in which crabs live significantly affects their diet. For instance, crabs inhabiting different water depths or levels of habitat complexity have distinct diets. This pattern is also observed in certain fish species, where habitat and the time of year are the primary drivers of their feeding habits (Hajisamae et al., 2004; Iqbal et al., 2023; Soe et al., 2021). However, the combined effects of species, sex, and habitat on the food and feeding habits of Scylla spp. have not been documented simultaneously.

Investigating feeding role is essential for assessing ecosystem’s structure and function (Krebs, 1989), contributing to an effective fisheries management (Viswanathan and Raffi, 2015), and application to domestication or aquaculture practices of the concerned species (Hernández-Téllez et al., 2024). This study specifically investigated how diet varies among species, between sexes, and across different habitats in the Gulf of Thailand (Pacific Ocean) and the Andaman Sea (Indian Ocean). The data provide crucial insights for aquaculture practices and the management of crab resources.

METHODS

Study site and sample collection

A total of 4,112 individual mud crabs belonging to three Scylla species were sampled across six coastal provinces of Thailand, comprising 3,746 Scylla olivacea, 314 S. paramamosain, and 52 S. tranquebarica. Sampling locations were strategically selected to represent both the Andaman Sea (Satun (ST), Trang (TR), and Ranong (RN) provinces), for the Indian Ocean, and the Gulf of Thailand (Pattani (PN), Songkhla (SK), and Surat Thani (SR) provinces), for the Pacific Ocean (Figure 1), thereby encompassing key fishing grounds for mud crabs along the Thai coastline. Specimens were obtained monthly from local fishermen between June 2022 and June 2023 using standard crab traps (2.5-3.0 cm mesh size) baited with fish, set 10-15 m apart during spring tides following Maae et al. (2025). Upon arrival at the laboratory of the Faculty of Science and Technology, Prince of Songkla University, for subsequent analysis, the crab samples were anesthetized by immersion in iced water and later frozen in a refrigerator to confirm death.

Figure 1
Map illustrating the study areas along Thailand’s coastal waters, including locations in the Gulf of Thailand (Pacific Ocean)-Pattani (PN), Songkhla (SK), and Surat Thani (SR)-and the Andaman Sea (Indian Ocean), comprising Satun (ST), Trang (TR), and Ranong (RN).

Laboratory analysis

Up to 30 crab samples per month were randomly selected for Scylla olivacea, whereas all monthly specimens of the other two species, due to limited number, were examined. Average carapace width (CW) of crabs examined (mean±SD) were 93.3±14.5, 107.6±21.3, and 115.7±18.5 for S. olivacea, S. paramamosain, and S. tranquebarica, respectively. Sex of male and female crabs was morphologically identified based on the abdominal flap, which is wider and more rounded in mature females (Hill, 1975; Robertson and Kruger, 1994), and triangular in male crabs (Keenan et al., 1998). Subsequently, the stomachs of all specimens were removed and preserved in 70% ethanol (Hajisamae et al., 2025) for further analysis.

The stomach was cut open with the aid of surgical scissors, and the entire gut was removed and examined on a Petri dish (Figure 2). Stomach fullness was then assessed on a scale from 0 (empty) to 4 (fully distended with food), which was expressed as empty, 1/4 full, 1/2 full, 3/4 full, and full stomachs (Pillay, 1952). Each individual prey item was examined under a stereo microscope and recorded to the lowest possible taxon. Next, the composition of each food item was determined visually using the modified-volumetric method (V%) on a scaled Petri dish by a single observer to avoid estimating bias (Hyslop, 1980). Altogether, sixteen types of dietary items, namely gastropod, fish, polychaete, crab, bivalve, sand, shrimp, plant materials, plastics, annelids, sipuncula, nemertea, nematodes, cephalopods, sponge, and metal, were categorized (Figure 3). Subsequently, the average number of food items for each species by site and sex was calculated.

Figure 2
Three species of the genus Scylla, (a) S. olivacea, (b) S. paramamosain, (c) S. tranquebarica, and (d) examination of stomach content of crabs during laboratory works (scale bar = 1 cm).

Figure 3
Food items in mud crab stomach; (a) gastropod, (b) fish, (c) crab, (d) bivalve, (e) sand, (f) plant material, (g) plastic, (h) shrimp, (i) annelid, (j) polychaete, (k) sipuncula, (l) nemertea, (m) cephalopod, (n) sponge, (o) nematode, and (p) metal. Scale bar 1 mm.

Diet attribute analysis

For each crab species, sexes, and habitats, the Vacuity Index (VI) and Fullness Index (FI) were determined. VI is defined as the percentage of empty stomachs relative to the total number of stomachs investigated. FI is defined as the average relative stomach fullness observed in the non-empty stomachs. Broadness of food was estimated by calculating the diet breadth index (Bi) using Levin’s standardized index (Krebs, 1989; Labropoulou and Papadopoulou-Smith, 1999) in the following formula:

$\mathrm{Bi}=(1/(n-1\left)\right)\left(\right(1,\sum _{i,j=1}^n\equiv P_{i{j}^2})-1)$

In which Bi is Levin’s standard index for predator i, Pij is the proportion of the diet of crab i that is composed of food j and n is the number of food items.

To understand the dietary overlap between species of the genus Scylla, the simplified Morisita-Horn index (Horn, 1966), based on %V data, was calculated as follows:

$CH=\frac{2\left(\sum _{i,j,k=1}^{n}Pij*Pik\right)}{\sum _{i,j=1}^{n}Pi{j}^2+\sum _{i,k=1}^{n}Pi{k}^2}$

In which CH is the Morisita-Horn index of diet overlap between species j and k; Pij is the percentage of food item i contributed by species j; Pik is the percentage of food item i used by species k; and n is the total number of food items. The degree of diet overlap was classified as low overlap (0.0-0.29), moderate overlap (0.30-0.59), and high overlap (between 0.60 and 1.00) according to Langton (1982).

Statistical analysis

One-way ANOVA was used to test the differences in the stomach fullness index (FI) and the average number of food items (AF) among the three Scylla species and between sites. A t-test was used to calculate the difference between male and female crabs. Prior to analysis, the raw data were log-transformed using Log (x+1) to reduce non-normality.

For multivariate analysis, the gut contents of 10-30 crab samples were randomly separated into groups, referred to as dietary samples for each species, habitat, and sex. Multi-dimensional scaling (MDS) was conducted using the PRIMER statistical package version 5.0 (Clarke and Gorley, 2001), with Bray-Curtis similarity, to assess the differences in diet compositions between the three Scylla species, study sites, and sex, based on square-rooted transformation of dietary sample data. Analysis of similarity (ANOSIM) determined the difference between those parameters. Once significant differences were identified, similarity percentage (SIMPER) was employed to examine which food items contributed most to the formation of each feeding factor.

RESULTS

Food compositions

Fish was the most dominant food item in the diets of all three Scylla species, at 56.0%, 57.8%, and 42.5% for Scylla olivacea, S. tranquebarica, and S. paramamosain, respectively. The second most dominant food item varied between species: crab for S. olivacea (15.1%) and bivalves for both S. paramamosain (22.7%) and S. tranquebarica (24.8%). Table 1 details the diet compositions for each species, collected from different sites and sexes.

Further analysis revealed that the dietary composition varied notably by sex and sampling location. Regarding sexual dimorphism, male S. olivacea exhibited a slightly higher proportion of crabs in their diet than females, accounting for 15.9% and 14.1% of total food items, respectively. Conversely, females consumed slightly more bivalves (13.4%) than males (12.4%) (Table 1). In S. paramamosain, the consumption of bivalves was higher compared with S. olivacea, with males and females consuming 20.8% and 24.6%, respectively. In contrast, consumption of crab as food was markedly higher in females (13.4%) than in males (4.1%) (Table 1). For S. tranquebarica, males consumed the highest proportion of bivalves (34.2%), while females fed only 2.9%. However, females ingested a higher proportion of crabs (15.9%) compared with males (6.2%) (Table 1).

Spatial variation in diet was also evident. S. olivacea generally exhibited a relatively consistent proportion of bivalves and crabs in their diet across most sites, except for Satun, Trang, and Ranong provinces. Additionally, this species consumed a higher percentage (>5%) of gastropods in Pattani, Surat Thani, and Trang provinces compared with other sampling locations. This contrasts with the dietary patterns observed in S. paramamosain, where a higher contribution of shrimp and crab items was noted in specimens from Satun province. In S. tranquebarica, bivalves (52.3%) predominated in the diet of individuals collected from Songkhla province (Table 1).

Table 1
Descriptive analysis of the dietary contribution of mud crabs (Scylla spp.) in the coastal waters of Thailand, by sex and site. (CW = carapace width, VI = vacuity index, FI = fullness index, Bi = diet breadth, AF = average number of food items, TF = total food items, UOM = unidentified organic materials).

Species	Sample (n)	CW	VI	FI	Bi	AF	TF	Gastropod	Fish	UOM	Crab	Bivalve	Sand	Shrimp	Plant material	Plastics	Polychaete	Annelid	Sipuncula	Nemertea	cephalopod	Sponge	Nematode	Metal
Scylla olivacea	3746 (2585)	89.6±15.6	69.0	2.3±1.1	0.12	1.6±0.9	16	4.1	56.0	6.1	15.1	13.1	0.4	2.2	0.6	1.7	0.1	0.1	0.2	0.03	0.004	0.03	0.2	0
Pattani	1504 (1043)	93.2±14.5	69.3	2.2±1.1	0.13	1.8±0.9	13	5.7	59.3	6.1	11.7	14.5	0.4	1.2	0.5	0.4	0.03	0.02	0	0	0	0.01	0.2	0
Songkhla	293 (162)	100.4±13.0	55.3	2.2±1.1	0.16	1.9±0.9	11	2.9	58.3	4.2	15.3	12.4	0.5	2.5	1.2	2.2	0	0	0	0	0	0.2	0.2	0
Surat Thani	126 (66)	99.6±14.8	52.4	1.8±0.9	0.21	1.9±1.1	11	7.1	52.3	4.7	15.8	13.1	1.2	3.8	0.9	0.4	0.3	0	0	0	0	0	0.3	0
Satun	478 (378)	83.3±16.4	79.1	2.4±1.1	0.09	1.9±0.8	13	0.9	67.8	3.2	17.5	2.6	0.4	3.2	0.4	2.7	0.3	0	0.6	0.3	0	0.01	0	0
Trang	530 (412)	86.2±17.2	77.7	2.8±1.1	0.26	1.7±0.9	12	6.1	35.0	9.8	11.6	32.4	0.3	2.8	0.8	0.4	0.2	0	0	0	0.02	0	0.5	0
Ranong	815 (524)	84.9±12.3	64.3	1.9±1.0	0.13	1.9±1.0	13	1.5	57	5.9	22.9	2.7	0.4	2.8	0.8	4.7	0.1	0.5	0.5	0	0	0.1	0	0
Male	1960 (1337)	89.8±15.4	68.2	2.2±1.1	0.12	1.8±0.9	16	3.7	56.6	5.7	15.9	12.4	0.4	2.0	0.7	1.9	0.1	0.1	0.1	0.1	0.01	0.1	0.2	0
Female	1786 (1248)	92.0±10.2	69.9	2.3±1.1	0.15	1.8±1.0	13	4.4	56.3	6.2	14.1	13.4	0.5	2.2	0.7	1.5	0.1	0.1	0.3	0.0	0.0	0.0	0.1	0.0
S. paramamosain	314 (157)	107.2±19.2	50.0	1.8±0.8	0.26	1.6±0.9	12	9.1	42.5	11.6	7.9	22.7	1.1	2.9	1.3	0.1	0.5	0	0	0	0	0	0.03	0.03
Pattani	152 (72)	107.8±21.2	47.4	1.8±0.8	0.19	1.5±0.9	10	9.8	55.8	7.5	5.8	19.6	0.1	1.3	0.01	0.1	0.1	0	0	0	0	0	0	0
Songkhla	86 (46)	106.6±13.8	53.5	1.7±0.8	0.40	1.6±0.9	11	10.2	29.6	19.3	8.3	23.5	1.3	3.7	3.9	0.1	0	0	0	0	0	0	0.04	0.1
Surat Thani	62 (32)	110.5±17.9	51.6	1.6±0.8	0.35	1.9±1.4	11	7.9	28.0	9.4	11.3	33.5	3.5	3.0	0.8	0.3	2.3	0	0	0.1	0	0	0	0
Satun	6 (4)	86.0±39.9	66.7	2.8±0.9	0.83	1.0±0	3	0	50	0	25	0	0	25	0	0	0	0	0	0	0	0	0	0
Trang	7 (3)	96.8±5.2	42.9	2.3±1.5	0.80	1.0±0	2	0	66.7	33.3	0	0	0	0	0	0	0	0	0	0	0	0	0	0
Male	188 (95)	105.2±18.4	50.5	1.7±0.8	0.19	1.6±0.9	12	8.1	51.5	10.4	4.1	20.8	0.5	3.7	0.7	0.1	0.03	0	0	0	0	0	0.02	0.1
Female	126 (62)	108.4±14.1	49.2	1.8±0.9	0.40	1.7±1.1	11	10.7	30.2	13.7	13.4	24.6	2.3	2.0	2.0	0.2	1.2	0.0	0.0	0.1	0.0	0.0	0.0	0.0
S. tranquebarica	52 (30)	116.6±20.4	57.7	1.6±0.9	0.21	1.6±0.9	8	4.5	57.8	1.1	10.7	24.8	0.4	0	0.7	0.03	0	0	0	0	0	0	0	0
Pattani	39 (22)	115.7±18.5	56.4	1.7±0.9	0.19	1.6±0.9	8	6.1	62.0	1.5	14.5	14.8	0.5	0	0.5	0.05	0	0	0	0	0	0	0	0
Songkhla	12 (8)	118.9±26.1	66.7	1.3±0.5	0.35	1.6±0.7	4	0	46.3	0	0	52.3	0.3	0	1.3	0	0	0	0	0	0	0	0	0
Surat Thani	1 (0)	121.8	0.0	-	-	-	-	-	-	-	-	-	-	-	-		-	-	-	-	-	-	-	-
Male	35 (21)	118.2±20.2	60.0	1.4±0.8	0.19	1.6±0.9	8	1.2	55.9	1.6	6.2	34.2	0.1	0	0.7	0.04	0	0	0	0	0	0	0	0
Female	17 (9)	118±12.8	52.9	1.9±1.1	0.19	1.8±0.4	6	10.0	69.2	0.0	15.9	2.9	1.7	0.0	0.4	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0

Diet attributes

The highest fullness index was recorded in Scylla olivacea (FI = 2.3 ± 1.1). Similarly, this species showed a higher vacuity index (VI = 69.0) compared with S. paramamosain (FI = 1.8 ± 0.8 and VI = 50.0) and S. tranquebarica (FI = 1.6 ± 0.9 and VI = 57.7) (Table 1).

Spatially, S. olivacea samples from Trang province exhibited the highest FI value. Conversely, S. paramamosain appeared to have the greatest FI in Satun province, while the lowest FI values of these two species were recorded in Surat Thani province. The highest FI of S. tranquebarica was recorded in Pattani province, while the lowest FI was found in Songkhla province. Statistical analysis revealed that the FI of S. olivacea varied significantly across sites (P < 0.001) and between sexes (P < 0.05). In contrast, no significant differences in FI were observed for S. paramamosain and S. tranquebarica either across sites or between sexes (P > 0.05) (Table 2).

Table 2
Statistical results for the fullness index (FI) and the average number of food items (AF) in three Scylla species by site (one-way ANOVA) and sex (t-test).

species	Site			Sex
				male	female
	n	FI	AF	n	n	FI	AF
Scylla olivacea	2598	<0.001	<0.001	1346	1252	<0.05	>0.05
S. paramamosain	159	>0.05	>0.05	96	63	>0.05	>0.05
S. tranquebarica	30	>0.05	>0.05	21	9	>0.05	>0.05

Moreover, the total number of food items varied between species (8-16 items), but the average number of food items (AF) for crabs was relatively similar (AF = 1.6 ± 0.9). Statistical analysis revealed significant variation in AF only among sites for S. olivacea (P < 0.001). No significant differences were observed between sexes for S. olivacea, nor between site and sex for S. paramamosain and S. tranquebarica (P > 0.05) (Table 2). Spatially, the Tukey HSD test indicated a significantly higher AF in Ranong compared to Pattani and Trang provinces (P < 0.05) (Table 1).

Levin’s standardized index (Bi) revealed low values for all three species (highest = 0.26, lowest = 0.12), suggesting specialized feeding habits. S. olivacea exhibited the narrowest dietary breadth (Bi = 0.12), indicating a particularly specific foraging strategy. In contrast, S. paramamosain and S. tranquebarica displayed slightly broader, yet still relatively low, Bi values of 0.26 and 0.21, respectively (Table 1).

Dietary overlap, assessed using the Morisita-Horn index of diet overlap (CH), was high (CH > 0.9) among the Scylla species, indicating substantial overlap in their consumed food resources. Notably, the highest degree of overlap was consistently observed between S. olivacea and S. tranquebarica (0.98) across all sampling locations. This significant overlap in dietary composition suggests the potential for intense intraspecific competition for food resources within shared habitats (Table 3).

Table 3
Diet overlaps (CH) between Scylla spp. across all six study areas in the coastal waters of Thailand.

All sites	Sample (n)	Scylla olivacea	S. paramamosain	S. tranquebarica
Scylla olivacea	2585	-
S. paramamosain	157	0.94	-
S. tranquebarica	30	0.98	0.94	-

Dietary variation between species, site, and sex

Multidimensional scaling (MDS) analysis of dietary samples from Scylla olivacea, S. paramamosain, and S. tranquebarica revealed a clear separation between the three species. S. olivacea was distinctly separated from S. paramamosain and S. tranquebarica, whereas S. paramamosain and S. tranquebarica showed some degree of overlap (Figure 4). Differences were tested and confirmed by Analysis of Similarities (ANOSIM), which indicated significant variation in the stomach contents of the three species (Global R = 0.524; P < 0.005) (Table 4). Moreover, pairwise tests confirmed that the dietary compositions differed significantly between the three species (P < 0.005). Similarity percentage analysis (SIMPER) further showed that the diet composition of S. olivacea was primarily contributed by crabs, fish, bivalves, and gastropods, with percentage contributions of 25.25%, 21.35%, 14.62%, and 10.96%, respectively. S. paramamosain diet was primarily composed of fish, bivalves, crabs, and gastropods, with percentage contributions of 32.00%, 27.05%, 14.05%, and 11.58%, respectively. In contrast, S. tranquebarica diet was mainly composed of two major food groups, fish and bivalves, with percentage contributions of 59.46% and 33.04%, respectively (Table 4).

Figure 4
Non-metric multidimensional scaling (MDS) ordination of the mean percentage volumetric contribution of dietary groups from ten dietary samples of three mud crab species (Scylla spp.: SO = Scylla olivacea, SP = S. paramamosain, and ST = S. tranquebarica), collected from six different sampling sites along the Thai coastal waters.

Table 4
Results of ANOSIM and SIMPER analyses for Scylla spp. comparing species (SO = Scylla olivacea, SP = S. paramamosain, and ST = S. tranquebarica), sex (M = males and F = females), and site (PN = Pattani, SK = Songkhla, SR = Surat, ST = Satun, TR = Trang, and RN = Ranong).

Species	Sex	Site	Contribution of food items (%)					Statistical value
			Fish	Crabs	Bivalves	Gastropods	Plastics	Global R	P value
SO			21.35	15.25	14.62	10.96	-	0.524	<0.005
SP			32.00	14.05	27.05	11.58	-
ST			59.46	-	33.04	-	-
SO	M		22.54	16.05	14.87	10.97	-	0.011	>0.05
SO	F		22.81	15.73	15.51	11.60	-
SP	M		43.48	3.95	31.88	12.18	-	-0.005	>0.05
SP	F		36.05	13.20	28.86	12.87	-
SO		PN	25.58	16.27	17.66	13.31	-	0.412	<0.005
		TR	21.86	15.97	21.53	13.32	-
		SK+SR*	26.94	18.89	17.47	12.51	-
		ST+RN*	25.79	18.92	10.64	-	11.69
SP		PN	49.62	-	28.81	16.09	-	0.017	>0.05
		SK	38.19	9.13	34.25	11.23	-
		SR	34.51	9.24	37.54	9.26	-

• * Since the ANOSIM test showed no significant difference (P > 0.05) between sites SK and SR, as well as ST and RN, the SIMPER analysis was conducted to evaluate the contribution of food items.

MDS analysis between male and female crabs showed no clear separation of groups for either S. olivacea (Figure 5a) or S. paramamosain (Figure 5b). ANOSIM analysis confirmed the absence of significant difference in diet contribution between male and female crabs of both species (S. olivacea, Global R = 0.011; P > 0.05; S. paramamosain, Global R = -0.005; P > 0.05) (Table 4).

Figure 5
Non-metric multidimensional scaling (MDS) ordination of the mean percentage volumetric contribution of dietary groups from 10 dietary samples of male (M) and female (F) mud crabs Scylla spp. including Scylla olivacea (a) and S. paramamosain (b), collected from six different sampling sites along the Thai coastal waters.

MDS analysis of S. olivacea across six different sampling sites revealed a distinct grouping pattern in the ordination. Notably, the dietary composition of S. olivacea from these six sites showed clear separations, with PN and RN, RN and TR, as well as RN and SR being distinctly separate. In contrast, PN, SK, and TR exhibited a slight overlap, whereas SR appeared more dispersed compared with the other sites (Figure 6a). Differences in dietary composition were significant, as confirmed by ANOSIM (Global R = 0.412; P < 0.005) (Table 4). Moreover, pairwise tests revealed significant differences (P < 0.005) in dietary composition across the six sites, except for SK and SR, as well as ST and RN, where no significant differences were observed (P > 0.05). Results from the SIMPER analysis indicated that diet compositions of S. olivacea from PN and TR were primarily composed of a combination of fish, bivalves, crabs, and gastropods, with percentage contributions of 25.58%, 17.66%, 16.27%, and 13.31% for PN, and 21.86%, 21.53%, 15.97%, and 13.32% for TR. Meanwhile, SK and SR were primarily composed of a combination of fish, crabs, bivalves, and gastropods, with percentage contributions of 26.94%, 18.89%, 17.47%, and 12.51%, respectively. ST and RN were primarily composed of a combination of fish, crabs, and bivalves, with percentage contributions of 25.79%, 18.92%, and 10.64% (Table 4). S. paramamosain from PN and SK mainly fed on fish, bivalves, and gastropods, with percentage contributions 49.62%, 28.81%, and 16.09% in PN, and 38.19%, 34.25%, and 11.23% in SK, respectively. In contrast, crabs from SR primarily consumed bivalves, fish, and gastropods, with percentage contributions of 37.54%, 34.51%, and 9.26%, respectively (Table 4).

Figure 6
Non-metric multidimensional scaling (MDS) ordination of the mean percentage volumetric contribution of dietary groups from ten dietary samples of mud crabs. Scylla olivacea (a) were collected from six sampling sites along the Thai coastal waters, including the Pacific Ocean: Pattani (PN), Songkhla (SK), Surat Thani (SR); and the Indian Ocean: Satun (ST), Trang (TR), and Ranong (RN). S. paramamosain (b) were collected from three sampling sites along the Thai coastal waters: Pattani (PN), Songkhla (SK), and Surat Thani (SR).

Conversely, MDS analysis of S. paramamosain from three sampling sites along the Gulf of Thailand-Pattani (PN), Songkhla (SK), and Surat Thani (SR)-revealed no clear separation of groups (Figure 6b). ANOSIM results confirmed no significant difference in dietary composition among the S. paramamosain from these three sites (Global R = 0.017; P > 0.05).

DISCUSSION

Scylla spp. are previously known to be omnivores and feed on a variety of food items (Quinitio and Parado-Estepa, 2008). During ontogeny, their diet changes from zooplankton during the larval stage to crustaceans, mollusks, worms, fish, and plants during the juvenile stages, and to burrowing organisms items, attached bivalves, small crabs, benthic invertebrates, or opportunistic scavenging when they reach sub-adult and adult stages (Thimdee et al., 2001; Webley, 2008). This study indicates that fish, crabs, bivalves, gastropods, and shrimp are the main food items consumed by three species of mud crabs, Scylla spp., from different regions across the coastal areas of Thailand. Fish was the most dominant food source for all crab species, with proportions ranging from 42.5% to 56.0%. However, all crab samples caught by crab traps were baited with fish, so the presence of fish in the diet in such large amounts may not fully reflect their natural consumption, though it remains an essential food item. In contrast, bivalves were the most dominant food item for Scylla paramamosain in SR, which could be associated with the physical characteristics of the environment and the availability of food sources in that area (Abdullah and Lee, 2016). This is because abundance and types of available food are important factors influencing feeding preference among crabs (Viswanathan and Raffi, 2015). Diet composition data of Scylla spp. suggests that they are primarily carnivorous, with relatively specialist predation, as they tend to choose only specific food items, mostly animal-based. Diet breadth values indicated that S. olivacea (0.12) is the most specialist predator, whereas S. paramamosain consumes a broader range of dietary components (0.26). Mud crabs are well known for their cannibalistic behavior (Kawamura et al., 2020). Notably, the consumption of crabs by these three species points to cannibalism. The proportions of 15.1%, 10.7%, and 7.9% crab components in the diets of S. olivacea, S. tranquebarica, and S. paramamosain, respectively, suggest different rates of cannibalism between the species. This observation may also support the consideration of S. paramamosain, which exhibits the least cannibalistic behavior, as a candidate for domestication or aquaculture development.

The diet components of mud crabs found align with those previously reported from different regions for other mud crab species. For example, Sara et al. (2007) reported that S. serrata in Lawele Bay, Southeast Sulawesi, Indonesia, fed on a variety of materials, including sand, shell, wood remains, mollusks, gastropods, crustaceans, fish meat, fish hard parts, plant leaf fragments, Sargassum, and eelgrass. Another study on S. serrata in Chilika Lagoon, India, reported that this species fed on mollusk, fish, crustacean, mixed food, plant material, detritus, and unidentified substances (Mohapatra et al., 2005). Similarly, Nayak et al. (2014) found that both S. serrata and S. tranquebarica in the same lagoon consumed crustaceans, mollusks fish, detritus, plants, and unidentified materials. However, S. olivacea fed more on crustaceans, mollusks, fish, detritus, mud, sand, and miscellaneous (Viswanathan and Raffi, 2015). Moreover, S. tranquebarica was reported to feed on crustaceans, molluscan remains, fish remains, detritus, and other debris (Nesakumari and Thirunavukkarasu, 2014).

For species-specific diet compositions, despite the considerable dietary overlap or a shared range of consumed foods between the three Scylla species, the results of diet breadth and multivariate statistical analyses reveal some degree of differences in their food and feeding habits. Specifically, S. olivacea exhibited a clear separation from S. paramamosain and S. tranquebarica in the MDS ordination, coupled with a lower diet breadth value compared with the latter two species. This divergence indicates differential dietary preferences, potentially reflecting their respective habitat utilization and food availability in the respective ecosystems (Campbell et al., 2021; Kunsook et al., 2014). S. olivacea predominantly inhabits lower salinity regions of mangrove ecosystems characterized by muddy substrates, whereas S. paramamosain and S. tranquebarica tend to favor higher salinity environments with finer sandy substrates (Fazhan et al., 2017b; Keenan et al., 1998). Consequently, the availability of accessible food resources is likely not uniform for these three species across these habitats, leading to variations in the types of food items consumed.

Knowledge of the dietary composition of different sexes of crabs is crucial for developing aquaculture and farming techniques for candidate species, particularly in formulating artificial diets (Amin-Safwan et al., 2019; Ikhwanuddin et al., 2009). Sex is considered another biological factor that influences the feeding habits of certain aquatic species. For example, variations in food and feeding habits have been reported between males, females, and the transient period of the hermaphrodite threadfin fish Eleutheronema tetradactylum (Iqbal et al., 2023). During its sex-transient period, the fish primarily consumed other fish (87.2%), whereas male and female fish predominantly fed on penaeid shrimp (66.5%) and other fish (51.3%), respectively. However, there is no existing record on the feeding habits of mud crabs of different sexes to date, and no variation in diet composition was found in this present study for S. olivacea and S. paramamosain, based on sex variation. This is confirmed by the average number of food items, which did not differ between the sexes of either species. Additionally, the results of the MDS analysis revealed no clear separation in grouping based on sex in the ordination, and ANOSIM confirmed that male and female crabs of both species consumed similar food compositions. These results indicate no variation in the food items ingested by male and female S. olivacea and S. paramamosain, which is consistent with the study of Viswanathan and Raffi (2015). Contributing factors to the similar diet between the two sexes may include comparable nutritional requirements, physiological characteristics, or possibly behavioral factors (Bauld et al., 2022; Winkler and Janicke, 2022).

Habitats are known to be an important factor influencing the feeding habits of many animals, such as fish (Hajisamae et al., 2004; Iqbal et al., 2023; Soe et al., 2021) and portunid crabs (Hajisamae et al., 2015). Variations in the food compositions of two mud crab species, S. olivacea and S. paramamosain, based on samples collected from different coastal areas, were recorded. For S. olivacea, samples collected from both the Andaman Sea (the Indian Ocean) and the Gulf of Thailand (the Pacific Ocean) clearly indicate that crabs from the same coastal area are likely to consume a similar range of food compositions compared with those from different oceans. This geographical difference may reflect the availability of food and the crabs’ ability to forage in each region. However, an identical food composition pattern was recorded for S. paramamosain inhabiting coastal habitats in the provinces of Pattani, Songkhla, and Surat Thani. This study enhances the understanding of mud crab feeding habits, which is a fundamental basis for aquaculture development and the management of mud crab resources. Additionally, it contributes to a better understanding of the ecological context via the feeding behavior of mud crabs.

CONCLUSION

In conclusion, this study revealed distinct dietary preferences among three sympatric mud crab species, Scylla olivacea, S. tranquebarica, and S. paramamosain, within Thai coastal ecosystems. Notably, habitat significantly influenced the diet of S. olivacea, emphasising the importance of regional ecological factors, whereas sex did not have a significant effect. The observed species-specific dietary variations and the identification of key prey items, such as fish, crabs, and bivalves, provide crucial insights for developing effective aquaculture practices and sustainable resource management strategies. Moreover, understanding these dietary patterns contributes to a broader comprehension of the trophic interactions within these valuable coastal ecosystems. These findings fulfil the need for considering both species-specific traits and environmental context when managing mud crab populations.

Acknowledgments

The authors would like to extend their heartfelt appreciation to the PSU-TUYF Charitable Trust Fund and Prince of Songkla University for their generous support of this project. We are also deeply grateful to the Faculty of Science and Technology at Prince of Songkla University for granting access to the laboratories and equipment vital to the success of our research. Sincere thanks are due to the fishermen from Pattani, Songkhla, Surat Thani, Satun, Trang, and Ranong for their invaluable assistance in data collection. Special appreciation is extended to Mr. Arun Lohem, Ms. Husneya Rensep, and colleagues for their dedication to field sampling and laboratory work.

Data Availability:

All data are available from the corresponding author upon reasonable request.

SUPPLEMENTARY MATERIAL

No supplementary materials are provided.

REFERENCES

• Abdullah, M. M. & Lee, S. Y. 2016. Meiofauna and crabs in mangroves and adjoining sandflats: is the interaction physical or trophic?.Journal of Experimental Marine Biology and Ecology, 479, 69-75. DOI: http://dx.doi.org/10.1016/j.jembe.2016.03.004
  » https://doi.org/10.1016/j.jembe.2016.03.004
• Alberts-Hubatsch, H., Lee, S. Y., Meynecke, J.O., Diele, K., Nordhaus, I. & Wolff, M. 2016. Life-history, movement, and habitat use of Scylla serrata (Decapoda, Portunidae): current knowledge and future challenges. Hydrobiologia, 763, 5-21. DOI: 10.1007/ s10750-015-2393-z
  » https://doi.org/10.1007/ s10750-015-2393-z
• Amin-Safwan, A., Nurazira, A., Syafiqah-Nurain, K. S., Mardhiyyah, M. P., Muhd-Farouk, H., Mahsol, H. H., Syahnon, M. & Ikhwanuddin, M. 2019. Comparison on natural diets dietary composition and foregut fullness between sexes of crenate swimming crab, Thalamita crenata (Rüppell, 1830) from Setiu Wetlands, Terengganu coastal waters, Malaysia. Journal of Sustainability Science and Management, 14(4), 25-37.
• Azra, M. N. & Ikhwanuddin, M. 2016. A review of maturation diets for mud crab genus Scylla broodstock: Present research, problems and future perspective. Saudi Journal of Biological Sciences, 23(2), 257-267. DOI: http://dx.doi.org/10.1016/j.sjbs.2015.03.011
  » https://doi.org/10.1016/j.sjbs.2015.03.011
• Bauld, J. T., Abernethy, K. A., Newton, J., Lehmann, D., Jones, I. L. & Bussière, L. F. 2022. Can diet niche partitioning enhance sexual dimorphism?.Ecology and Evolution, 12(12), e9599. DOI: 10.1002/ece3.9599
  » https://doi.org/10.1002/ece3.9599
• Blaber, S. J. M. 1997. Fish and fisheries of tropical estuaries London, Chapman & Hall.
• Campbell, T. I., Tweedley, J. R., Johnston, D. J. & Loneragan, N. R. 2021. Crab diets differ between adjacent estuaries and habitats within a sheltered marine embayment.Frontiers in Marine Science, 8, 564695. DOI: https://doi.org/10.3389/fmars.2021.564695
  » https://doi.org/10.3389/fmars.2021.564695
• Clarke, K. R. & Gorley, R. N. 2001. Primer v5: user manual/tutorial. Plymouth, PRIMER-E Ltd.
• Fazhan, H., Waiho, K. & Ikhwanuddin, M. 2017a. Non-indigenous giant mud crab, Scylla serrata (Forskål, 1775) (Crustacea: Brachyura: Portunidae) in Malaysian coastal waters: a call for caution. Marine Biodiversity Records, 10, 1-7. DOI: 10.1186/s41200-017-0128-8
  » https://doi.org/10.1186/s41200-017-0128-8
• Fazhan, H., Waiho, K., Norfaizza, W. I. W., Megat, F. H. & Ikhwanuddin, M. 2017b. Inter-species mating among mud crab genus Scylla in captivity. Aquaculture, 471, 49-54. DOI: http://dx.doi.org/10.1016/j.aquaculture.2017.01.005
  » https://doi.org/10.1016/j.aquaculture.2017.01.005
• Hajisamae, S., Chou, L. M. & Ibrahim, S. 2004. Feeding habits and trophic relationships of fishes utilizing an impacted coastal habitat, Singapore. Hydrobiologia, 520, 61-71. DOI: https://doi.org/10.1023/B:HYDR.0000027727.90956.a9
  » https://doi.org/10.1023/B:HYDR.0000027727.90956.a9
• Hajisamae, S., Fazrul, H. & Pradit, S. 2015. Feeding ecology of Portunus pelagicus (Linnaeus, 1758) (Brachyura, Portunidae) in the southern Gulf of Thailand: influences of habitat, season, size class, shell stage and ovigerous condition. Crustaceana, 88(10-11), 1163-1180. DOI: https://doi.org/10.1163/15685403-00003475
  » https://doi.org/10.1163/15685403-00003475
• Hajisamae, S., Soe, K. K., Pradit, S., Chaiyvareesajja, J. & Fazrul, H. 2022. Feeding habits and microplastic ingestion of short mackerel, Rastrelliger brachysoma, in a tropical estuarine environment. Environmental Biology of Fishes, 105(2), 289-302. DOI: https://doi.org/10.1007/s10641-022-01221-z
  » https://doi.org/10.1007/s10641-022-01221-z
• Hajisamae, S., Soe, K. K., Maae, S., Chaymongkol, S. & John, A. 2025. Population structure and feeding habits of Carcinoscorpius rotundicauda in the bay environment, Southern Gulf of Thailand. Fisheries Research, 281, 107216. DOI: https://doi.org/10.1016/j.fishres.2024.107216
  » https://doi.org/10.1016/j.fishres.2024.107216
• Hamasaki, K., Matsui, N. & Nogami, M. 2011. Size at sexual maturity and body size composition of mud crabs Scylla spp. caught in Don Sak, Bandon Bay, Gulf of Thailand. Fisheries Science, 77, 49-57. DOI: https://doi.org/10.1007/s12562-010-0307-6
  » https://doi.org/10.1007/s12562-010-0307-6
• Hernández-Téllez, A. R., Cajas-Flores, J. M., Ordiano-Flores, A., Calle-Morán, M. D. & Bucheli-Quiñonez, R. J. 2024. Feeding habits of the South Pacific hake, Merluccius gayi, in Ecuador, Tropical Eastern Pacific Ocean. Ocean and Coastal Research, 72, e24034.
• Hill, B. J. 1975. Abundance, breeding and growth of the crab Scylla serrata in two South African estuaries. Marine Biology, 32, 119-126. DOI: https://doi.org/10.1007/BF00388505
  » https://doi.org/10.1007/BF00388505
• Hill, B. J. 1979. Biology of the crab Scylla serrata (Forskål) in the St Lucia system. Transactions of the Royal Society of South Africa, 44(1), 55-62. DOI: https://doi.org/10.1080/00359197909520079
  » https://doi.org/10.1080/00359197909520079
• Horn, H. S. 1966. Measurement of «overlap» in comparative ecological studies. The American Naturalist, 100(914), 419-424.
• Hyslop, E. J. 1980. Stomach contents analysis: a review. Journal of Fish Biology, 17(4), 411-429. DOI: https://doi.org/10.1111/j.1095-8649.1980.tb02775.x
  » https://doi.org/10.1111/j.1095-8649.1980.tb02775.x
• Ikhwanuddin, M., Shabdin, M. L. & Abol-Munafi, A. B. 2009. Natural diet of blue swimming crabs found in Sarawak coastal water. Journal of Sustainability Science and Management, 4(1), 85-92.
• Ikhwanuddin, M., Liyana, A. N., Azra, M. N., Bachok, Z. & Abol-Munafi, A. B. 2014. Natural diet of blue swimming crab, Portunus pelagicus at Strait of Tebrau, Johor, Malaysia. Sains Malaysiana, 43(1), 37-44.
• Imai, H., Cheng, J. H., Hamasaki, K. & Numachi, K. I. 2004. Identification of four mud crab species (genus Scylla) using ITS-1 and 16S rDNA markers. Aquatic Living Resources, 17(1), 31-34. DOI: https://doi.org/10.1051/alr:2004007
  » https://doi.org/10.1051/alr:2004007
• Iqbal, T. H., Hajisamae, S., Lim, A., Jantarat, S., Wang, W. X. & Tsim, K. W. 2023. Feeding habits of four-finger threadfin fish, Eleutheronema tetradactylum, and its diet interaction with co-existing fish species in the coastal waters of Thailand. PeerJ, 11, e14688. DOI: https://doi.org/10.7717/peerj.14688
  » https://doi.org/10.7717/peerj.14688
• Islam, R., Hajisamae, S., Pradit, S., Perngmak, P. & Paul, M. 2018. Feeding habits of two sympatric loliginid squids, Uroteuthis (Photololigo) chinensis (Gray, 1849) and Uroteuthis (Photololigo) duvaucelii (d’Orbigny, 1835), in the lower part of the South China Sea. Molluscan Research, 38(3), 155-162. DOI: https://doi.org/10.1080/13235818.2017.1409066
  » https://doi.org/10.1080/13235818.2017.1409066
• Kawamura, G., Yong, A. S. K., Roy, D. C. & Lim, L. S. 2020. Shelter colour preference in the purple mud crab Scylla tranquebarica (Fabricius). Applied Animal Behaviour Science, 225, 104966. DOI: https://doi.org/10.1016/j.applanim.2020.104966
  » https://doi.org/10.1016/j.applanim.2020.104966
• Keenan, C., Davie, P. J. & Mann, D. L. 1998. A revision of the genus Scylla de Haan, 1833 (Crustacea: Decapoda: Brachyura: Portunidae). The Raffles Bulletin of Zoology, 46(1), 217-245.
• Krebs, C. J. 1989. Ecological methodology New York, Harper and Row.
• Kunsook, C., Gajaseni, N. & Paphavasit, N. 2014. The feeding ecology of the blue swimming crab, Portunus pelagicus (Linnaeus, 1758), at Kung Krabaen Bay, Chanthaburi Province, Thailand. Tropical Life Sciences Research, 25(1), 13-27.
• Labropoulou, M. & Papadopoulou-Smith, K.-N. 1999. Foraging behaviour patterns of four sympatric demersal fishes. Estuarine, Coastal and Shelf Science, 49(1), 99-108. DOI: https://doi.org/10.1016/S0272-7714(99)80014-6
  » https://doi.org/10.1016/S0272-7714(99)80014-6
• Langton, R. W. 1982. Diet overlap between Atlantic cod, Gadus morhua, Silver hake, Merluccius bilinearis, and fifteen other northwest Atlantic finfish [Fish predators]. Fishery Bulletin, 80(4), 745-759.
• Le Vay, L. 2001. Ecology and management of mud crab Scylla spp. Asian Fisheries Science, 14(2), 101-111.
• Maae, S., Chuaduangpui, P., Hajisamae, S., Masniyom, P., Chaymongkol, S., Jantarat, S. & Saengkaew, S. 2025. Distribution and abundance of mud crabs (Crustacea: Portunidae) in Pacific and Indian Ocean coasts of Thailand. Biodiversitas, 26(9), 4534-4544. DOI: https://doi.org/10.13057/biodiv/d260925
  » https://doi.org/10.13057/biodiv/d260925
• Mohapatra, A., Mohanty, R. K., Bhatta, K. S. & Mohanty, S. K. 2005. Food and feeding habits of the mud crab Scylla serrata (Forsskal) from Chilika Lagoon. Journal of the Inland Fisheries Society of India, 37(2), 1-7.
• Nayak, L., Mohapatra, R., Padhi, P. & Sharma, S. D. 2014. Food and feeding habit of Scylla serrata and Scylla tranquebarica from Chilika Lagoon, east coast of India. Journal of International Academic Research for Multidisciplinary, 2(10), 467-478.
• Nesakumari, C. S. A. & Thirunavukkarasu, N. 2014. Food and feeding behaviour of mud crab Scylla tranquebarica (Fabricius, 1798). Indian Journal of Veterinary and Animal Sciences Research, 43(3), 229-235.
• Nurdiani, R. & Zeng, C. 2007. Effects of temperature and salinity on the survival and development of mud crab, Scylla serrata (Forsskål), larvae. Aquaculture Research, 38(14), 1529-1538. DOI: https://doi.org/10.1111/j.1365-2109.2007.01810.x
  » https://doi.org/10.1111/j.1365-2109.2007.01810.x
• Pillay, T. V. R. C. 1952. A critique of the methods of study of food of fishes. Journal of the Zoological Society of India, 4, 185-200.
• Prasad, P. N. & Neelakantan, B. 1988. Food and feeding of the mud crab Scylla serrata Forskal (Decapoda: Portunidae) from Karwar waters. Indian Journal of Fisheries, 35(3), 164-170.
• Quinitio, E. T. & Parado-Estepa, F. D. 2008. Biology and hatchery mangrove crabs Scylla spp. Aquaculture Extension Manual. 2nd ed. Tigbauan, SEAFDEC.
• Robertson, W. D. & Kruger, A. 1994. Size at maturity, mating and spawning in the portunid crab Scylla serrata (Forskål) in Natal, South Africa. Estuarine, Coastal and Shelf Science, 39(2), 185-200. DOI: http://doi.org/10.1006/ecss.1994.1057
  » https://doi.org/10.1006/ecss.1994.1057
• Sara, L., Aguilar, R. O., Laureta, L. V., Baldevarona, R. B. & Ingles, J. A. 2007. The natural diet of the mud crab (Scylla serrata) in Lawele Bay, southeast Sulawesi, Indonesia. Philippine Agricultural Scientist, 90(1), 6-14.
• Sathiadhas, R. & Najmudeen, T. M. 2004. Economic evaluation of mud crab farming under different production systems in India. Aquaculture Economics & Management, 8(1-2), 99-110. DOI: https://doi.org/10.1080/13657300409380355
  » https://doi.org/10.1080/13657300409380355
• Soe, K. K., Pradit, S. & Hajisamae, S. 2021. Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat. Journal of Fish Biology, 99(4), 1430-1445. DOI: https://doi.org/10.1111/jfb.14851
  » https://doi.org/10.1111/jfb.14851
• Soe, K. K., Maae, S., Jaafar, Z., Chuaduangpui, P., Jantarat, S. & Hajisamae, S. 2024. Plastic ingestion by three species of Scylla (Brachyura) from the coastal areas of Thailand. Marine Pollution Bulletin, 198, 115914. DOI: https://doi.org/10.1016/j.marpolbul.2023.115914
  » https://doi.org/10.1016/j.marpolbul.2023.115914
• Tewfik, A., Bell, S. S., McCann, K. S. & Morrow, K. 2016. Predator diet and trophic position modified with altered habitat morphology. PLoS One, 11(1), e0147759. DOI: https://doi.org/10.1371/journal.pone.0147759
  » https://doi.org/10.1371/journal.pone.0147759
• Thimdee, W., Deein, G., Sangrungruang, C. & Matsunaga, K. 2001. Stable carbon and nitrogen isotopes of mangrove crabs and their food sources in a mangrove-fringed estuary in Thailand. Benthos Research, 56(2), 73-80. DOI: https://doi.org/10.5179/benthos1996.56.2_73
  » https://doi.org/10.5179/benthos1996.56.2_73
• Vale, J. G., Barrilli, G. H. C., Chahad-Ehlers, S. & Branco, J. O. 2022. Factors influencing the feeding habits of the ghost crab Ocypode quadrata (Fabricius, 1787) on subtropical sandy beaches. Estuarine, Coastal and Shelf Science, 269, 107817. DOI: https://doi.org/10.1016/j.ecss.2022.107817
  » https://doi.org/10.1016/j.ecss.2022.107817
• Viswanathan, C. & Raffi, S. M. 2015. The natural diet of the mud crab Scylla olivacea (Herbst, 1896) in Pichavaram mangroves, India. Saudi Journal of Biological Sciences, 22(6), 698-705. DOI: https://doi.org/10.1016/j.sjbs.2015.08.005
  » https://doi.org/10.1016/j.sjbs.2015.08.005
• Waiho, K., Fazhan, H., Quinitio, E. T., Baylon, J. C., Fujaya, Y., Azmie, G., Wu, Q., Shi, X., Ikhwanuddin, M. & Ma, H. 2018. Larval rearing of mud crab (Scylla): what lies ahead. Aquaculture, 493, 37-50. DOI: https://doi.org/10.1016/j.aquaculture.2018.04.047
  » https://doi.org/10.1016/j.aquaculture.2018.04.047
• Webley, J. A. C. 2008. The ecology of the mud crab (Scylla serrata): their colonisation of estuaries and role as scavengers in ecosystem processes (Doctor in Philosophy). Brisbane: Griffith University.
• Winkler, L. & Janicke, T. 2022. Diet quality impairs male and female reproductive performance and affects the opportunity for selection in an insect model. Ecology and evolution, 12(11), e9533. DOI: https://doi.org/10.1002/ece3.9533.
  » https://doi.org/10.1002/ece3.9533
• Wootton, R. J. 1998. Ecology of Teleost Fishes 2nd ed. Dordrecht, Kluwer Academic Publishers.

• AI Use disclosure:
  Artificial intelligence tools (e.g., ChatGPT) were used exclusively to refine the English writing of this manuscript. The content was carefully reviewed by the authors to ensure consistency and correctness, and the authors are fully responsible for the final version of the manuscript.
• Funding:
  This research was supported by the PSU-TUYF Charitable Trust Fund, Hong Kong, under the project Sustainable Utilization of Mud Crabs, and by Prince of Songkla University, Thailand.

Edited by

• Editor:
  Rubens Lopes

Publication Dates

• Publication in this collection
  20 July 2026
• Date of issue
  2026

History

• Received
  18 Apr 2025
• Accepted
  22 Mar 2026