Spiral valve parasites of blue and common thresher sharks as indicators of shark feeding behaviour and ecology

This study documented the parasite faunas of the spiral valves of blue sharks Prionace glauca (L. 1758) and common thresher sharks Alopias vulpinus (Bonnaterre, 1788) caught in the California Current Large Marine Ecosystem (CCLME) north of the Mexican border. The spiral valves of 18 blue and 19 thresher sharks caught in the CCLME from 2009 to 2013 were examined for parasites. Seven parasite taxa were found in blue sharks and nine in threshers. The tetraphyllidean cestode Anthobothrium sp. (78% prevalence) was the most common parasite in blue sharks, and the phyllobothriid cestode Paraorygmatobothrium sp. (90% prevalence) was the most common in threshers. An adult nematode of the genus Piscicapillaria was found in threshers for the first time and may be a new species. Adult individuals of Hysterothylacium sp. were found in both shark species. The adult acanthocephalan Rhadinorhynchus cololabis and remains of the parasitic copepod Pennella sp. – both parasites of Pacific saury, Cololabis saira – were found in the intestines of threshers, indicating recent feeding on saury. This study paves the way for a more comprehensive examination, including more samples and a wider variety of shark species, to provide a greater understanding of shark feeding behaviour and possibly provide information on shark population biology.     

Vertebrate diets derived from trophically transmitted fish parasites in the Bothnian Bay

Parasites that are transmitted through predator–prey interactions may be used as indicators of trophic relationships between organisms. Yet, they are rarely used as such in the construction of topological (predator–prey) food webs. We constructed food webs of vertebrate trophic interactions using observed diet alone, trophically transmitted parasites alone, and the combination of the two based on data from 31 species of fish from the Bothnian Bay, Finland. The fish food web contained 530 links derived from observed diet, 724 links inferred from parasitism, and 1,058 links calculated from a combination of both stomach contents and parasites. This sub-web constructed from stomach contents had a mean of 17.1 links per fish species, while that using parasites had 23.4 links per fish. Combining the two diet indicators yielded 34.1 links per fish species, illustrating the complementarity of the two methods. Mean number of prey species per fish species was 12.5 using observed diet items, 15.8 using parasites, and 24.5 using both measures together. Mean number of predators per fish species was 7.4 using observed diet, 11.7 using parasites and 15.0 using both. A positive correlation was found between the mean number of parasites and the number of prey taxa in the diet among the fishes. Omnivorous fish had the highest diversity of both parasite species and prey items, while benthophagous fish had among the lowest. Mean total abundance and mean total prevalence of parasites correlated positively with fish size, with piscivores being the largest with the highest abundance and prevalence, while planktivores and benthivores had the lowest. Trophically transmitted parasites may be used to help construct vertebrate sub-webs and derive information about food web processes. Parasites alone provided equivalent if not more information than observed diet. However, resolution is improved by using parasites and observed diet together.     

Metazoan parasite communities and diet of the velvet belly lantern shark Etmopterus spinax (Squaliformes: Etmopteridae): a comparison of two deep‐sea ecosystems

By combining an examination of stomach contents yielding a snapshot of the most recent trophic niche and the structure of parasite communities reflecting a long‐term feeding niche, this study aimed at gaining more comprehensive information on the role of the small‐sized deep‐water velvet belly lantern shark Etmopterus spinax in the local food webs of the Galicia Bank and the canyon and valley system of the Avilés Canyon, which have been both proposed for inclusion in the Natura 2000 network of protected areas. As far as is known, this study provides the first comparative parasite infracommunity data for a deep‐sea shark species. Component parasite communities in E. spinax were relatively rich, whereas the infracommunities were rather depauperate, with similar low diversity at both localities. The significant differences in the composition and structure of both parasite communities and prey assemblages indicate differential effects of the two deep‐sea ecosystems on both long‐term and most recent trophic niches of E. spinax. These results underline the importance of the use of multivariate analyses for the assessment of geographical variation in shark populations based on parasites and diet data.     

Diet of the Worm Lizard,Diplometopon zarudnyi (Nikolsky, 1907), in Riyadh province,Saudi Arabia (Reptilia: Trogonophidae)

We analysed the diet composition of 133 specimens of the Worm Lizard, Diplometopon zarudnyi, in Riyadh province, Saudi Arabia. Analysis of stomach contents revealed that 90 specimens (66.6%) had prey items in their gut. The stomach content consisted mainly of small invertebrate prey (beetles), mainly larvae of Dermestes sp., but also imagines of Dermestes maculatus and Rhynchophorus ferrugineus. Dermestes sp. constitutes over 99% of the total food items, showing a high selectivity in food intake. The high number of beetles in the stomach contents indicates that this lizard forages very frequently. Specimens collected during winter had empty stomachs. The high proportion of fossorial prey items and the occasional records of other stomach contents show that D. zarudnyi only occasionally forages on the surface.     

Trophic Structure of One Deep-sea Benthic Fish Community in the Eastern Canadian Arctic: Application of Food, Parasites and Multivariate Analysis

Synopsis As new arctic marine fisheries develop there is need for a comprehensive ecosystem approach to long-term management. This approach recognizes the importance of community interactions such as food web structure and trophic patterns. We determined whether hierarchical clustering (guild formation) is an effective method of trophic evaluation in deep-sea Artic fish communities using stomach content and parasite data with size class, and evaluated the application of endohelminth communities (parasite species transmitted in the food) as indicators of trophic status. Cluster analysis using food group abundance with size class of fish revealed the presence of 11 guilds within the community, however the same analysis using parasite data showed little correlation between food and parasites. Redundancy analysis (RDA) within the 11 guilds also revealed no significant correlations between food group and parasite abundance suggesting that this type of ordination is not suited for environments containing mainly generalist feeders. RDA of individual taxa without a priori guild designation found that taxa in benthic deep-sea communities are defined by their ability to exploit prey species in more than one habitat zone. Benthic fish species were significantly correlated with benthic food groups and parasites that utilize benthic intermediate hosts whereas benthopelagic–pelagic species fed on a higher diversity of prey species and were infected by a larger number of non-host specific parasites. Eigenanalysis and Monte Carlo results showed that parasites and food groups are highly correlated, indicating that parasite community analysis is an effective tool for predicting feeding strategies in Arctic marine environments. It also suggests that in most cases endoparasite infections alone could be used for trophic evaluation in the absence of stomach content data.     

Diet composition of the Thornback Ray,Raja clavata Linnaeus, 1758 (Elasmobranchii: Rajidae) in the Turkish Aegean Sea

The diet of Raja clavata (Thornback Ray) was studied in 2008–2009 in S??ac?k Bay in the eastern Mediterranean, based on 187 stomach contents obtained by commercial trawl operations. 40 different prey species were found. Mysidacea, Parapenaeus longirostris and Plesionika sp. were the most abundant prey items. The results indicate that the main prey varies considerably depending on the ecological characteristics of the habitat.     

Parasite fauna and food contents of Notothenia c.f. angustata Hutton, 1875 (Pisces: Nototheniidae) from two intertidal localities of the Arauco Gulf,Chile

We studied the parasite fauna and food contents of 38 juvenile of Notothenia c.f. angustata specimens captured in the intertidal of Island Santa María and Maule, in the Arauco Gulf, Chile. Trophic habits of Notothenia c.f. angustata were not different between localities, which was mainly algae. A total 11 parasitic taxa among were found with the digenean Lecitasther macrocotyle, cestode larvae Tetraphyllidea and Diphyllidea and nematode Ascarophis sp. being the dominant taxa. The abundance of parasites was similar in the two localities, although the infracommunity richness was higher in fish from Maule. The most abundant parasite was L. macrocotyle in hosts from Isla Santa María, while those from Maule they were the Diphyllidea larvae and nematodes Ascarophis sp. The body length of the hosts was not a good predictor of the variations in abundance and richness at infracommunities, probably because of the early ontogenetic stage of fishes.     

Feeding strategy of the Deepwater Goby,Chasar bathybius,in the Southern Caspian Sea (Osteichthyes: Gobiidae)

Eleven animal taxa were identified as prey of the Deepwater Goby, Chasar bathybius (Kessler, 1877), by analysing stomach contents: these were some species of Gobiidae, Clupeidae, Atherina boyeri, Carassius gibelio, Liza sp., Cardium sp., and Rhithropanopeus sp. With a frequency of 66%, Neogobius fluviatilis was the most prevalent food item, and was the dominant prey taxon in all seasons and age groups. C. bathybius exhibited a specialist feeding strategy on this fish and the other prey types. The dietary breadth is highest in spring according to the Shannon index.     

Diet and foraging opportunism of the Guiana dolphin (Sotalia guianensis) in the Abrolhos Bank,Brazil

Diet analysis allows exploring how coastal dolphins interact with the environment and their role in the marine food webs. We studied the diet and feeding ecology of the Guiana dolphin, Sotalia guianensis, through analysis of stomach content from 42 animals stranded on the eastern coast of Brazil. A total of 1,336 semidigested prey items (fish, otoliths, cephalopod beaks, and crustaceans) were identified. Teleost fish comprised the most frequent food item (92% of the total), followed by cephalopods, and crustaceans. Prey belonged to 34 taxa and richness in individual stomachs varied from 1 to 15 prey taxa. Prey were generally small, but showed a significant trend to increase in size with dolphin length. The main prey of Guiana dolphins were demersal, estuarine, and sound-making fish such as catfish and sciaenids. No sex-related differences in diet were found. Diet composition varied seasonally and occurrence of prey items was coherent with breeding or high abundance periods of some fish species and squids. Our study shows the importance of demersal prey from estuarine and soft-sediment habitats to Guiana dolphin in the Abrolhos Bank and reveals that feeding habits are generalist and opportunistic, with diet reflecting the seasonal abundance and availability of prey.     

Stomach content analysis of juvenile, scalloped hammerhead shark Sphyrna lewini captured off the coast of Mazatlán, Mexico

We quantified the diet of juvenile, scalloped hammerhead shark Sphyrna lewini in the area off Mazatlan, Sinaloa, Mexico, to understand their feeding ecology this shark. The prey species of Sphyrna lewini were identified and quantified from stomach content analysis. In addition, we determined the variations between genders. During two fishing seasons (2000–2001 and 2001–2002), we analyzed 232 stomachs, of which 85% contained food. The trophic spectrum was composed of three species of cephalopods, six of crustaceans and 19 species of fish from mainly pelagic and benthic habitats. According to the Index of Relative Importance (%IRI), the cephalopod Loliolopsis diomedeae with IRI = 18%, fish of the family Carangidae IRI = 25% and family Synodontidae IRI = 19% constituted the main prey in general. The trophic niche width was <0.4, which indicated that S. lewini juveniles in this area feed on a wide range of prey items, though they showed a preference for a few prey items.     

The occurrence of some metazoan parasites of Atlantic cod, Gadus morhua L., in relation to age and sex of the host in Balsfjord (70°N), North Norway

Age and sex differences in the occurrence of some metazoan parasites were investigated in 243 cod (Gadus morhua L.) from Balsfjord, a subarctic fjord in northern Norway. Thirteen species of parasite were studied, comprising seven nematodes, three parasitic copepods, one acanthocephalan, one cestode and one digenean. The nematode Anisakis simplex showed significant increases in both prevalence and mean abundance with host age, while the digenean Hemiurus levinseni showed a significant increase in mean abundance with age. The increases probably result from a long parasite life-span for A. simplex and changes in the feeding pattern of cod with age for H. levinseni. Prevalence of the nematode Contracaecum sp. and mean abundance of the acanthocephalan Echinorhynchus gadi were significantly higher in male than in female cod, whereas mean abundance of H. levinseni was significantly higher in female cod. These results suggest that there may be differences in feeding behaviour between male and female cod in Balsfjord. Accepted: 14 November 1999     

Determinants and consequences of interspecific body size variation in tetraphyllidean tapeworms

Tetraphyllidean cestodes are cosmopolitan, remarkably host specific, and form the most speciose and diverse group of helminths infecting elasmobranchs (sharks, skates and rays). They show substantial interspecific variation in a variety of morphological traits, including body size. Tetraphyllideans represent therefore, an ideal group in which to examine the relationship between parasite body size and abundance. The individual and combined effects of host size, environmental temperature, host habitat, host environment, host physiology, and host type (all likely correlates of parasite body size) on parasite length were assessed using general linear model analyses using data from 515 tetraphyllidean cestode species (182 species were included in analyses). The relationships between tetraphyllidean cestode length and intensity and abundance of infection were assessed using simple linear regression analyses. Due to the contrasting morphologies between shark and batoid hosts, and contrasting physiologies between sharks of the Lamnidae family and other sharks, analyses were repeated in different subsets based on host morphology and physiologies (“sharks” vs. batoids) to determine the influence of these variables on adult tetraphyllidean tapeworm body size. Results presented herein indicate that host body size, environmental temperature and host habitat are relatively important variables in models explaining interspecific variations in tetraphyllidean tapeworm length. In addition, a negative relationship between tetraphyllidean body size and intensity of infection was apparent. These results suggest that space constraints and ambient temperature, via their effects on metabolism and growth, determine adult tetraphyllidean cestode size. Consequently, a trade-off between size and numbers is possibly imposed by external forces influencing host size, hence limiting physical space or other resources available to the parasites.     

Predators and trematode parasites jointly affect larval anuran functional traits and corticosterone levels

Non‐consumptive predator effects may have dramatic consequences for host–parasite interactions by influencing the ability of prey items to avoid, resist, or tolerate infection. Both predators and parasites can affect host traits, such as growth rates and behavior, and these effects may in part be mediated through shared physiological pathways (e.g. the glucocorticoid stress hormone, corticosterone [CORT]). Here, we examined the effects of trematode parasites (Digena: Echinostomatidae) and predator (larval odonate) exposure on larvae of two amphibian species (Rana sylvatica and R. clamitans) in laboratory experiments. First, we measured behavior and CORT responses of tadpoles exposed to predator chemical cue in combination with parasite cue or under direct exposure to parasites. We then measured the combined effects of predator cue and parasite infection on survival and traits. Evidence for effects of parasite cue in our study was equivocal, but we found novel interactive effects of parasites and predators on larval frogs. Parasites and predators had antagonistic effects on CORT, behavior, and morphology, and negative synergistic effects on development. In addition, parasite infection and predator cues additively reduced activity levels of both species and growth in wood frogs. Negative effects of parasite infection on survival and traits were dose‐dependent for both species, although wood frogs generally experienced stronger effects of infection than green frogs. Our results emphasize the importance of considering effects of parasites as well as predators, since both can have strong effects on survival and the combination can have both additive and non‐additive effects on key traits. These effects likely have important implications for amphibian population dynamics, community structure, and conservation.     

Ontogenetic and seasonal feeding habits of the annular seabream (Diplodus annularis L.) in Zostera sp. beds, eastern Adriatic Sea

The ontogenetic and seasonal feeding habits of 489 individuals of Diplodus annularis L. in Zostera sp. beds were studied using frequency of occurrence, numeric percentage, percentage by weight and an index of relative importance (IRI). The Schoener overlap index was used to compare diets by fish size and seasons. Diet composition including 18 different prey taxa was evidently heterogenous among annular seabream size groups, with no significant dietary overlap. In relation to body size, juveniles were omnivorous and preferred algae and plants, while adults were omnivorous and preferred animals. Principal prey items by decreasing importance were Chlorophyta (dominant taxa Cladophora sp. and Enteromorpha flexuosa), Decapoda (dominant species Upogebia pusilla), Gastropoda (important species Rissoa ventricosa and Alvania sp.), Bivalvia and Spermatophyta, as well as other food items (mostly unidentified Crustacea and fish eggs). Differences in diets among seasons were not significant.     

Helminth parasite diversity discloses age and sex differences in the foraging behaviour of southern lapwings (Vanellus chilensis)

Parasites with heteroxen cycles are important sources of information on the trophic relations of hosts. This is particularly instructive for species whose age‐based or sex‐based differences are hardly detected by behavioural observations. Here, we describe the helminth community of the omnivorous southern lapwing (Vanellus chilensis) and evaluate whether it is affected by the host's sex, age and body size. The species is sexually monomorphic in body length, but males are slightly heavier than females. We analysed 112 individuals collected in Curitiba, Brazil, in March 2010. All hosts were parasitized. The helminth community was composed of 10 species (the digeneans Leucochloridium parcum and Athesmia sp., the cestode Infula macrophallus, the acantocephalans Plagiorhynchus sp., Centrorhynchus sp., Mediorhynchus sp., and an unidentified Gigantorhynchida, and the nematodes Heterakis psophiae, Dispharynx nasuta and an unidentified Capillariidae), seven of which were novel reports for this host species. Prevalence ranged from <1% to 99%. Whereas I. macrophallus was the most prevalent species, D. nasuta showed the highest mean intensity and abundance of infection. The former was found in most hosts as single male–female pairs, suggesting the occurrence of intrasexual competition. The infracommunities of juvenile birds showed a higher parasite species richness than those of adult males and females, suggesting the exploitation of a wider array of prey. However, the three classes harboured seven parasite species. Differences in parasite diversity (lower in juveniles, intermediate in adult males and higher in adult females) reflect the evenness in the distribution of parasite specimens among taxa in each age–sex class and are compatible with differences in their foraging strategy. Finally, we conclude based on the cycles of the heteroxen species that southern lapwings preyed upon molluscs, coleopterans, woodlice and earthworms.     

Feeding habits of sand smelt (Atherina boyeri, Risso 1810) in Trichonis Lake (Western Greece)

The feeding habits of sand smelt (Atherina boyeri, Risso, 1810) from Trichonis Lake (Western Greece) were investigated. Stomach contents were analyzed from 240 specimens with total lengths ranging from 35 to 112 mm. Samples were taken at monthly intervals (January–December 1997). Of the total number of stomachs examined, 53 were empty (22.1%). However, values varied greatly with season (maximum in January: 50%; minimum in August: 7.6%). Prey analyses of stomach contents identified 15 important items (%Rn > 0.05) belonging to six major groups: crustacean (copepods, cladocera), mollusca (bivalve: larvae), insects (larvae), cestode worms and finfish (fry and eggs). Dominant prey were larvae of the bivalve Dreissena polymorpha (%Rn = 33.8), the copepods Eudiadomus drieschi (%Rn = 26.4) and the cladocera Diaphanosoma brachyurum (%Rn = 24.2). The importance of cladocera and copepods decreased with increasing size of the sand smelt, while the importance of bivalve larvae, fish eggs and finfish fry increased with increasing sand smelt size. Seasonal changes in diet composition and prey abundance in sand smelt stomachs were recorded as coinciding with the seasonal composition and abundance of the zooplankton community in the surface layers of Trichonis Lake. Bivalve larvae were the dominant prey of A. boyeri during January to May, while copepods and cladocera dominated from June to December.     

基于高通量测序的象山港海域黑鲷(Acanthopagrus schlegelii)食性分析

选取象山港黑鲷个体为研究对象,以18S rDNA为靶标,利用Illumina Miseq高通量测序方法研究黑鲷饵料生物组成特征,分析不同龄组黑鲷的食性异同。通过序列比对,共在黑鲷胃含物中鉴定出41个属中的62种饵料生物,分属9个门,其中节肢动物门（Arthropoda）、绿藻门（Chlorophyta）和软体动物门（Mollusca）是黑鲷饵料生物的优势组成门类。从饵料生物相对丰度和出现频率上分析,石莼（Ulva lactuca）、熊本牡蛎（Crassostrea sikamea）、胸刺水蚤（Centropages hamatus）、日本蟳（Charybdis japonica）、毛蚶（Scapharca subcrenata）和褐菖鲉（Sebastiscus marmoratus）是黑鲷的优势饵料物种,所占饵料生物总相对丰度的比重达60.90%。相似性分析检验（ANOSIM）结果显示：1至4龄黑鲷个体的饵料生物组成不存在显著性差异。与传统食性分析方法相比,高通量测序法在黑鲷饵料生物检测灵敏性上显现了较为明显的优势,保障黑鲷等重要物种的种群稳定对于该海域具有重要的生态和经济意义。     

A survey of the helminths of Rattus sordidus,the canefield rat,together with a description of Ancistronema coronatum n. g., n. sp. (Nematoda: Chabertiidae)

The digestive systems of 86 canefield rats from Ingham, Queensland were examined for parasites. One species of cestode and seven species of nematode were found, all but one being new host records. The helminth community was characterised in terms of core, secondary and satellite species. No core species were identified, but Nippostrongylus typicus and Odilia emanuelae were identified as secondary species. All other species were identified as satellite species. The strongyloid nematode Ancistronema coronatum n. g., n. sp. is described. Ancistronema differs from other genera in the Chabertiidae in having a short buccal capsule and in the number and shape of the elements of the internal and external leaf crowns. This is the first record of a strongyle from Australian rodents. It is postulated that it came into Australia with ancestral Rattus sp. hosts which colonised Australia from Indonesia less than a million years ago.     

Dynamics of a parasite assemblage of the Vermilion Rockfish Sebastes miniatus from northwestern Baja California,México

A parasite assemblage of Sebastes miniatus from northwestern Baja California, México, was composed of a total of 12 species: five ectoparasites (two monogeneans and three parasitic copepods) and seven endoparasites (two digeneans, one cestode, three nematodes, and one acanthocephala). Five of these parasites constituted new genera records to the genus Sebastes, and nine were new geographic records. The most abundant species were the endoparasites Parabothriocephalus sagitticeps, Hysterothylacium sp., and Anisakis sp., and the specific richness ranged from 1 to 8 parasite species per host. The most important parasite species in terms of prevalence were Microcotyle sebastis (93 %) and Anisakis sp. (92 %). The mean abundance of parasites found in S. miniatus showed significant variations over the year, with maximum values (31.7 individuals/host) in August, and minimum (0.39 individuals/host) in February. P. sagitticeps showed the highest mean intensity of infection (190.4 parasites/host), followed by Anisakis sp. (127.2 parasites/host) and Hysterothylacium sp. (46.6 parasites/host). The presence of larval stages of the nematodes Anisakis, Pseudoterranova, and Hysterothylacium is particularly important due to their high abundance and prevalence and because they may represent a human health risk (anisakiasis). Rockfishes (family Scorpaenidae) of the genus Sebastes constitute one of the most important groundfish resources in the American and Mexican northern Pacific Ocean, both for recreational and for the commercial fisheries of California and Baja California. These rockfish species makes up a substantial part of the Mexican cuisine.