Cyrtograpsus Angulatus Research Articles

Agonistic Behaviour and Sound Production during Male–Male Varunid Crabs (Cyrtograpsus angulatus, Dana 1851) Encounters

Crustacean sounds are the main contributor to shallow water soundscape biophonic components. Here, we investigate the sound production of Cyrtograpsus angulatus, one of the most important intertidal decapods of the Southwestern Atlantic Ocean. Underwater audio and video were recorded during encounters among male pairs. Two kinds of experimental settings were conducted involving same size (SS) and different-size (DS) male crabs. Behavioural states, behavioural events and sound emission were investigated. SS spent more time in contact and still behaviour and showing competitive interactions than did DS. Crabs presented body displays involving chelae, legs, and maxillae movements with the same frequency in both settings. Our results demonstrate the production of impulsive sounds in male C. angulatus with high rates during contact and still behaviour (specifically during agonistic interactions and body displays without contact between individuals). Furthermore, we were able to describe behaviour-related variability within impulsive sounds. These outcomes provide a better understanding of the role and behavioural context of these sounds in the natural soundscape.

Tracking synthetic microdebris contamination in a highly urbanized estuary through crabs as sentinel species: An ecological trait-based approach.

Synthetic microdebris (particles of <5 mm) are a worldwide concern because they can affect the community structure of the aquatic ecosystems, organisms, and even food webs. For the biomonitoring of synthetic microdebris (especially microplastics, MPs), mainly benthic invertebrates are used, but crabs have been less studied in the literature. We studied the synthetic microdebris contamination in water, sediments, and three representative intertidal crabs (Neohelice granulata, Cyrtograpsus angulatus and Leptuca uruguayensis) with different lifestyles from the Bahía Blanca estuary, Argentina. The results obtained show the presence of cotton-polyamide (PA), polyethylene (PE), and polyethylene terephthalate (PET) in surface waters. In sediments, we identified cellulose modified (CE), polyester (PES), polyethylene (PE), and alkyd resin, while in crabs, cotton-PA and CE were the predominant ones. The MPs abundance ranged from 8 to 68 items L-1 in surface water, from 971 to 2840 items Kg-1 in sediments, and from 0 to 2.58 items g-1 ww for the three species of crabs. Besides, paint sheets ranged from 0 to 17 in the total samples, with Cr, Mo, Ti, Pb, Cu, Al, S, Ba and Fe on their surface. There were significant differences between the microdebris abundances in the abiotic matrices but not among crabs species. The ecological traits of the different crabs helped to understand the accumulation of synthetic microdebris, an important characteristic when determining the choice of a good biomonitor.

Dietary bioaccumulation of UV-absorbing compounds, and post-ingestive fitness in larval planktotrophic crustaceans from coastal SW Atlantic

Increased ultraviolet radiation (UVR) is a major environmental stressor for marine organisms. The response of planktotrophic larvae of holo- and meroplanktonic crustaceans fed dietary algae grown under different light regimes and contents of UV-absorbing compounds (UACs), was experimentally evaluated. Paracalanus parvus copepodites and Cyrtograpsus angulatus zoeae were fed diatoms grown under two radiation treatments: PAR (400–700 nm, produced by 40 W cool-white fluorescent bulbs) and PAR + UVR (280–700 nm; adding Q-Pannel UV-A-340 lamps to PAR fluorescent bulbs). An absorption peak at 337 nm (UVR range) was observed only for larvae fed UVR-irradiated diatoms. After 144 h of ad libitum feeding, larvae were exposed to UVR for 24 h. Mortality rates were ~80% in individuals fed PAR-reared microalgae, and ~10% for those fed UV-irradiated microalgae. Results point to the importance of UACs conferring some tolerance to planktotrophic larvae under increased environmental UVR stress. Yet, acquired tolerance is differential among larvae, with implications for zooplankton ecology.

Effect of biological and anthropogenic sound on the orientation behavior of four species of brachyuran crabs

The settlement phase of crustaceans is critical and can ultimately affect their population structure. Underwater sound has been proposed as one of the most important sensory cues used by these animals during this phase because it can provide direction and habitat quality information. Here, we evaluated the effect of different acoustic signals (biological and anthropogenic) on the orientation response of different stages (megalopae and juveniles) of 4 brachyuran crabs (Cyrtograpsus angulatus, C. altimanus, Neohelice granulata, Leptuca uruguayensis) from Mar Chiquita coastal lagoon in Argentina. A binary choice chamber system was used, and different sound sources (crustacean, fish and motorboat signals) selected from recordings of the lagoon soundscape were reproduced. C. angulatus megalopae and juveniles responded positively towards crustacean signals, while juveniles responded negatively towards fish sounds. N. granulata juveniles orientated negatively towards crustacean, motorboat and fish signals. C. altimanus and L. uruguayensis juveniles did not respond to fish signals. The results support the idea that invertebrates can discriminate among conspecific signals and highlight the role of sound on prey-predator relationships. The behavioral orientation response to the motorboat sound evidences a presumably negative effect of anthropogenic sound on the biological interactions of species. This information is important, given the urgent need to increase knowledge about coastal marine lagoons to enhance their protection, especially considering the role of the key species of crabs in this habitat.

Reproductive anatomy and receptivity of the female Cyrtograpsus angulatus (Brachyura: Varunidae): Implications for the mating system

The study of the functional anatomy of the female reproductive organs of Brachyura is often used in the classification and establishment of phylogenetic relationships. Besides, it allows us to draw inferences about the reproductive strategies and mating systems of crabs. Using histology and scanning electron microscopy we assessed the reproductive biology of Cyrtograpsus angulatus females by studying: the vulvae morphology, the receptive period duration, the spawning capacity and its relation to the seminal receptacle weight or carapace width, and the anatomy of the seminal receptacle. The vagina was of the concave type with an operculate vulva whose hinge became mobile when the female was receptive. The presence of striae in the vulvae hinge were related to the carapace width and maturity stage. Receptivity occurred during the intermolt period and lasted from 5 to 7 days. The duration of receptivity was independent of the seminal receptacle weight. Large females had seminal receptacles full of sperm and more frequently spawned a brood of eggs compared to small females. The seminal receptacle showed a threshold filling capacity. The histological anatomy of the seminal receptacle corresponds to the general pattern described for other Brachyura. A ventral connection of the ovary to the seminal receptacle was found. The presence of an oviduct valve at the junction of the ovary and the seminal receptacle was evident in non receptive females, but not evident in receptive ones. The seminal receptacle contained an unstructured mass of sperm with no evidence of separate ejaculates. As a result, a female centered competitive mating system is suggested in this species.

Paleoenvironmental implications of the first fossil record of Cyrtograpsus angulatus (Decapoda: Brachyura: Varunidae) from the mid-holocene of Argentina (northeastern Buenos Aires)

The estuarine crab Cyrtograpsus angulatus is an important burrower found in intertidal muddy and rocky shores along the modern coasts of northern Patagonia to southern Brazil on the Atlantic side and from Chile to Perú on the Pacific side. This species is commonly associated with populations of the crab Neohelice granulata in modern sites, with variable impacts of their interactions in the environment. When they become agonistic, the latter species always wins the battle for space and burrows. The previous fossil record of crabs from the mid-Holocene of Buenos Aires was restricted to Neohelice granulata, with no mention of any fossil exoskeletal elements of C. angulatus along its distribution. Herein i describe the first unambiguous fossils of C. angulatus, comprising six almost complete to isolated specimens from the mid-Holocene of Buenos Aires, Pereyra Iraola Park, taphonomic and paleoenvironmental implications of the bispecific assemblage are discussed.

Presence of Cyrtograpsus angulatus Dana, 1851 (Decapoda, Brachyura) on the Chilean northern Patagonian coast

The marine fauna of decapod Crustacea, in all its diversity, can be negatively affected as a result of environmental changes, both on a local or a global scale. The present study aims to report the existence ofCyrtograpsus angulatusDana, 1851, on the northern Patagonian coast, while concurrently describing some other decapod species associated with the various habitats.C. angulatuswas originally described from the Chilean coast north of 36°43′S, and the present study revealed its presence down to 44°S. In the estuaries investigated,C. angulatusis the exclusive decapod species, whereas in coastal zones it can coexist with other species of marine decapods. Nevertheless, according to the null model of the co-occurrence of species, the species associations tested did not show any structured pattern. Some ecological and biogeographical patterns in relation to this species and its biocoenoses are discussed.

Glucose homeostasis in the euryhaline crab Cytograpsus angulatus: Effects of the salinity in the amylase, maltase and sucrase activities in the hepatopancreas and in the carbohydrate reserves in different tissues.

We studied the existence, biochemical characteristics and response to different environmental salinities of amylase, maltase and sucrase activity in the intertidal euryhaline crab Cyrtograpsus angulatus (Dana, 1852) along with the response to distinct salinities of glycogen and free glucose content in storage organs. Amylase, maltase and sucrase activities were kept over a broad range of pH and temperature and exhibited Michaelis-Menten kinetics. Zymography showed the existence of two amylase forms in crabs exposed to 35 (osmoconformation) and low (6-10psu; hyper-regulation) or high (40psu) (hypo-regulation) salinities. Carbohydrases activity in the hepatopancreas and glycemia were not affected in crab exposed to different environmental salinities. In 6 and 40psu, the glycogen content in anterior gills was lower than in 35psu. In 6, 10 and 40psu, glycogen concentration in hepatopancreas, muscle and posterior gills were similar to that in 35psu. Free glucose concentration in chela muscle was higher in 6 and 40psu than in 35psu. The existence and biochemical characteristics of carbohydrases activity and the adjustments in concentration of glycogen in anterior gills and free glucose in chela muscle suggests the ability to perform complete hydrolysis of glycogenic substrates and to keep glucose homeostasis in relation to acclimation to different salinity conditions.

Influence of Reduced Salinity on the Histochemical Fiber Type Composition of the Claw Closer Muscle of Two Estuarine Crab Species, Cyrtograpsus angulatus and Neohelice granulata (Decapoda: Varunidae)

Fil: Longo, Maria Victoria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Trypsin and N-aminopeptidase (APN) activities in the hepatopancreas of an intertidal euryhaline crab: Biochemical characteristics and differential modulation by histamine and salinity

No studies are available about biochemical characteristics and modulation (i.e. by endogenous and/or environmental cues) of trypsin (a key digestive endoprotease) in hepatopancreas of intertidal euryhaline crabs neither on the possible concomitant modulation of key ectoproteases such as aminopeptidase-N (APN) involved in final steps of protein digestion. Furthermore, nothing is still known in decapods crustaceans about the role of histamine as primary chemical messenger for modulation of main components of digestive process (i.e. proteases). We determined biochemical characteristics and investigated the effect of histamine injections; of histamine in vitro and of acclimation of individuals to low and high salinity on trypsin and aminopeptidase-N (APN) activities in the hepatopancreas of the euryhaline crab Cyrtograpsus angulatus (Dana 1851). Trypsin activity was maximal at pH7.4 and at 45°C. APN activity increased from pH6.6 to 7.6–9.0 and was maintained high at 37–45°C. Both activities exhibited Michaelis-Menten kinetics (apparent Km: trypsin=0.36mM; APN=0.07mM). The injection of 10−4M histamine decreased trypsin activity (about 40%) in hepatopancreas while did not affect APN activity. Similarly, in vitro 10-4M histamine decreased trypsin activity (about 52%) in hepatopancreas but not APN activity. Trypsin activity in the hepatopancreas was not affected by acclimation of crabs to low (10psu) or high (40psu) environmental salinity while APN activity was increased (about 200%) in 10psu. The results show the differential modulation of trypsin and APN by distinct cues and point to histamine as modulator of intracellular trypsin by direct action on the hepatopancreas.

Uptake, metabolism and sub-lethal effects of BDE-47 in two estuarine invertebrates with different trophic positions

Two microcosm types -sediment-biota and biota-biota- were constructed to simulate different pathways of BDE-47 uptake, metabolism and oxidative stress effects in two key estuarine invertebrates (polychaete Laeonereis acuta and crab Cyrtograpsus angulatus). In the sediment-biota experiment, both species were exposed to spiked sediments; an environmentally reported and a high concentration of BDE-47 for 2 weeks. In the biota-biota experiment, crabs were fed with polychaetes pre-exposed to BDE-47 in the sediment-biota experiment. The sediment-biota experiment first revealed that polychaetes significantly accumulated BDE-47 (biota-sediment accumulation factor >2; p < 0.05) to a much greater extent than the crab organs (muscle, hepatopancreas, gills) at both sediment concentrations. For oxidative stress responses, polychaete and crab tissues exposed to spiked sediment showed a significant increase (p < 0.05) of only glutathione S-transferase (GST) activity with respect to controls in both BDE-47 concentrations. No lipid peroxidation (TBARS) or total antioxidant capacity (ACAP) changes were evident in the species or organs exposed to either BDE-47 sediment concentration. The biota-biota experiment showed that feeding crabs with pre-exposed polychaetes caused BDE-47 accumulation in organs as well as significant amounts of BDE-47 eliminated through feces (p < 0.05). Unlike the sediment-biota exposure, crabs fed with pre-exposed BDE-47 polychaetes showed the most conspicuous oxidative stress responses. Significant changes in GST and ACAP in both hepatopancreas and gills, in addition to enhanced TBARS levels in the hepatopancreas with respect to controls (p < 0.05), revealed that BDE-47 assimilated by invertebrates represents a potential source of toxicity to their predators. No methoxylated metabolites (MeO-PBDEs) were detected during BDE-47 metabolism in the invertebrates in either of the two different exposure types. In contrast, hydroxylated metabolites (OH-PBDEs) were detected in polychaetes and crab organs/feces in both experiments. Our results demonstrate that PBDE hydroxylation is one of the main biotransformation routes of BDE-47 in estuarine animals, which could be associated with the oxidative stress responses found.

Interaction between a mobile and a sessile species in SW Atlantic mudflats: Lack of negative effects of the mud crab Cyrtograpsus angulatus Dana, 1851 on filtration rate and growth of the infaunal clam Tagelus plebeius (Lightfoot, 1786)

Biogenic modifications of benthic environment by organism's activities like feeding, burrowing or excretion have in general negative implications for cohabiting sessile infauna, especially for suspension-feeders. However, the outcome of these interactions depends on several biological and physical characteristics and thus, it is not easily predictable in soft bottom environments. The stout razor clam Tagelus plebeius, an estuarine, infaunal and sessile filter feeder species, coexists in Mar Chiquita coastal lagoon (Argentina, 37° 32′S, 57° 19′W) with the mud crab Cyrtograpsus angulatus, a very mobile benthic consumer. Due to the intense crab activity and consequent habitat transformation, we predicted negative effects on clams' filtration rate and their growth. However, an inclusion experiment showed that T. plebeius filtration rate was higher in enclosures when crabs were present responding to enhanced turbidity and chlorophyll a. Additionally, another experiment showed that mean condition index as well as mean shell growth increment of clams was not negatively affected by crabs, although maximum values of shell growth increments (mm) were smaller in crab inclusions. Our findings suggest that the clams can exploit the increased food availability (i.e., Chl a) generated by resuspension and are also not affected by the disturbance that crabs can make over sediment surface. In conclusion, contrary to the generalized outcome proposed for this kind of interaction, crabs do not have a negative effect on T. plebeius.

Carriage of Clostridium perfringens by benthic crabs in a sewage-polluted estuary

The Estuary of Bahía Blanca (EBB), Argentina, is an important wetland under intense sewage pollution. We investigated the occurrence of Clostridium perfringens (CP) in populations of two benthic crabs (Neohelice granulata and Cyrtograpsus angulatus) and in sediment from the EBB. CP was found in 49.1% of the crabs and all of the isolates were identified as type A. The alpha (cpa) and enterotoxin (cpe) encoding genes were identified. Genetic analyses identified 13 novel sequence types, and found no clustering among isolates, suggesting that CP is not part of the crabs’ commensal flora. CP carriage was 51 times more likely in crabs from the area nearest sewage outfalls compared with crabs from a reference site. Our in vitro experiments suggest that the carriage of CP in crabs is transient. The use of these benthic crabs as monitoring organisms of sewage pollution in coastal habitats is proposed.

Histological and Histochemical Study of the Hepatopancreas of Two Estuarine Crab Species, Cyrtograpsus angulatus and Neohelice granulata (Grapsoidea, Varunidae): Influence of Environmental Salinity.

The aim of this study was to analyze the histology and the histochemical distribution of glycoproteins (GPs) and lipids of the hepatopancreas of Cyrtograpsus angulatus and Neohelice granulata acclimated to salinities of 10 psu (hyperregulation) and 35 psu (osmoconformation). Sections of the hepatopancreas of adult male crabs were treated with hematoxylin-eosin; Masson trichrome; Alcian Blue (pHs 2.8, 1.0, 0.5); Toluidine Blue (pHs 5.6, 4.2); periodic acid Schiff; Sudan Black and Red. At salinity 35 psu, the hepatopancreas of both species exhibited typical histological features, whereas at salinity 10 psu, detachment of the basal lamina, desquamated epithelium, disrupted brush border, loss of intercellular cohesion, hypertrophied tubular lumen, and hemolymph infiltration between cells were observed in some zones. Resorptive cells (R-cells) and vacuoles of blister-like cells (B-cells) of both species show a higher glycogen content at 35 psu than at 10 psu. At lower salinities, the cytoplasm of the different cell types evidence higher contents of carboxylated GPs in N. granulata and of su If at ed GPs in C. angulatus. At both salinities, and at the two pHs in N. granulata and at pH 5.6 in C. angulatus, the brush border, the vacuoles of B-cells and the peritrophic membrane show metachromasia. R-cell vacuoles and the cytoplasm of all cell types--except for the E-cells--at all salinities in both species show abundant lipid droplets. The results of the present study contribute significant data to the histophysiology of crustacean decapods, favoring the comprehension of the complex adjustment mechanisms facing saline stress in euryhaline crabs.

Population dynamic of two digenean species parasitizing the grass shrimp Palaemonetes argentinus Nobili 1901 (Decapoda: Palaemonidae) in a lentic environment from Argentina.

The microphallids Microphallus szidati and Levinseniella cruzi parasitized at least three crustacean species as second intermediate host in Mar Chiquita coastal lagoon: the crabs Neohelice granulata and Cyrtograpsus angulatus and the grass shrimp Palaemonetes argentinus. Palaemonetes argentinus acts as host for both metacercariae in brackish and freshwater environments; however the seasonal variations of these digeneans in freshwater habitats remain unexplored. The aim of the present study was to analyze the seasonal dynamic of the larval digenean populations parasitizing P. argentinus in a lentic environment. From the total sample of 600 P. argentinus collected seasonally, 28.370 and 194 metacercariae of M. szidati and L. cruzi, respectively, were recovered. Microphallus szidati was characterized by high prevalence, 100% in all seasons. In contrast, L. cruzi presented low prevalence values, which increased towards summer. The two species of digeneans exhibit seasonal fluctuations in intensity of infection, which was related to host size. Temporal variation of larval digenean assemblage in the crustacean host is probably associated with the presence of the other hosts included in their life cycles. The high values of prevalence found for M. szidati in Nahuel Rucá lagoon suggest that P. argentinus could favor the contact between the larval digenean and the definitive hosts, establishing the presence of M. szidati also in freshwater environments and, thus, increasing the presence of the parasite in different areas of Mar Chiquita coastal lagoon.

Morphology of the Claw Closer Muscle in Two Estuarine Crab Species (Crustacea, Varunidae): An Ultrastructural Study

We analyzed the ultrastructural features of the claw closer muscles in two estuarine crabs, Cyrtograpsus angulatus and Neohelice granulata, by transmission electron microscopy. Adult male crabs at intermolt stage were collected in the Mar Chiquita Coastal Lagoon (Buenos Aires, Argentina). The muscle fibers of both species showed evident striations, peripheral and intermyofibrillar nuclei, clefts in continuity with T and Z tubules, sarcoplasmic reticulum and T tubules forming dyads and triads usually located between the A and I bands, and mitochondria located mainly beneath the sarcolemma. Glycogen was observed as diffuse, small particles among myofilaments. The claw closer muscle of C. angulatus exhibited two fiber types: one with relatively fast-contracting fibers (shorter sarcomeres, myofilaments with an ordered arrangement, lineal Z discs, a well-developed sarcotubular system) and fatigue-resistant (numerous large mitochondria); and the other type, with slower-contracting fibers (longer sarcomeres, less orderly arranged myofilaments, wavy Z discs, a less developed sarcotubular system) and less resistant to fatigue (lower mitochondrial density). N. granulata showed only the slow, less resistant to fatigue type. The fibers less resistant to fatigue and more slowly contracting would presumably be used primarily for displays and agonistic interactions, whereas fast fibers with abundant mitochondria would be associated with continuous movements during feeding and grooming.

Habitat‐specific shape variation in the carapace of the crab C yrtograpsus angulatus

Different environmental and sex conditions induce phenotypic responses (behavioural, morphological and physiological) in many species. The crab Cyrtograpsus angulatus inhabits contrasting intertidal habitats, such as rocky shores and salt marshes, where they are exposed to a wide diversity of predators. However, their anti-predator responses differ substantially between these two habitats: while crabs in the salt marshes use or built burrows or they simply hide by burying in the sediment into the tidal channels, on rocky shores they find shelter below rocks, inside crevices or under seaweeds in tidal pools. Considering that refuges in salt marshes can be adjusted by the crabs according to their size and the morphology, while in rocky shores they have to fit in the available refuges, we expect that the body shape differs between individuals from each intertidal habitat. In order to test this hypothesis, we collected male and female crabs from a salt marsh and a rocky shore, separated by 3 km, in San José Gulf, Patagonia, and compared the carapace shapes using geometric morphometric methods. The results showed that carapace shape variation is explained by the interaction between sex and habitats. In both sexes, the mean carapace shape on the rocky shore is more slender and more lengthened than in the salt marsh individuals. Furthermore, the posterior margin of the female carapaces was wider than that of male carapaces, which were slender and more rounded posterolaterally, independent of the intertidal habitat.

Energy density empirical predictor models for three coastal crab species in the Southwestern Atlantic Ocean

Energy density was measured for key intertidal and subtidal crab species in the Southwestern Atlantic Ocean. Empirical models were developed to link energy density to water content (expressed as dry weight) and the fit to data was compared between different taxonomic and gender aggregations. Predictive power of models with different levels of aggregation and the effect of using a model of a surrogate species or group were also evaluated. Neohelice granulata (Dana, 1851) (3728 J/g wet weight) contained the highest energy density followed by Cyrtograpsus angulatus Rathbun, 1914 (3334 J/g wet weight), and C. altimanus Dana, 1851 (3042 J/g wet weight). Females (3645 J/g wet weight) showed higher energy density compared to males (3074 J/g wet weight). Dry weight of whole individuals provided good energy density predictions, with low predictive error when using species or same genus models (6.4-9.6% for the median error). Predictive power improved when more specific levels of taxonomic aggregation were employed. Interestingly, the two congeneric Cyrtograpsus did not differ in their energy density predictor model, suggesting a unique model could be used for this genus. This paper provides valuable inputs for bioenergetic modeling in coastal ecosystems in the Southwestern Atlantic.

Effect of environmental salinity and dopamine injections on key digestive enzymes in hepatopancreas of the euryhaline crab &lt;i&gt;Cyrtograpsus angulatus&lt;/i&gt; (Decapoda: Brachyura: Varunidae)

Fil: Michiels, Maria Soledad. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico - CONICET - Mar del Plata. Instituto de Investigaciones Marinas y Costeras; Argentina; Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina;

Interspecific kleptoparasitism by Brown-headed Gulls (Chroicocephalus maculipennis) on two hosts with different foraging strategies: a comparative approach

Kleptoparasitism is a well known foraging strategy used opportunistically by many seabirds. Our study compares the strategies performed by a facultative kleptoparasite species, the Brown-hooded Gull (Chroicocephalus maculipennis), associated with two hosts with different foraging strategies, the American Oystercatcher (Haematopus palliatus) and Red-gartered Coot (Fulica armillata). In total, 97% of the prey items stolen from Oystercatchers were the clam Tagelus plebeius, and all prey items stolen from Coots were the crab Cyrtograpsus angulatus. The attack rate by Gulls (number of kleptoparasitic attacks per unit time) did not differ significantly between Oystercatchers and Coots, but the success rate of attacks (successful kleptoparasitic attacks as a proportion of total attacks) was greater for attacks on Coots than on Oystercatchers. The mean rate of feeding (number of stolen items ingested per minute) by Brown-hooded Gulls did not differ with host. Gulls strongly selected large prey when stealing food. The comparison of net intake (cost—benefit balance) for each kleptoparasite—host system showed that profitability was 3.5 times higher when kelptoparsitising Coots than when stealing from Oystercatchers. We suggest future work should study in more detail the costs and benefits for kleptoparasites with multiple hosts in similar systems elsewhere.