Nematodes Infect, But Do Not Manipulate Digging By, Sand Crabs, Lepidopa benedicti (original) (raw)
Related papers
PeerJ, 2017
Two digging decapod crustaceans, the sand crab species Lepidopa benedicti and the mole crab species Emerita benedicti, both live in the swash zone of fine sand beaches. They were examined for two parasites that infect decapod crustaceans in the region, an unidentified nematode previously shown to infect L. benedicti, and cestode tapeworm larvae, Polypocephalus sp., previously shown to infect shrimp (Litopenaeus setiferus). Lepidopa benedicti were almost always infected with both parasite species, while E. benedicti were rarely infected with either parasite species. This difference in infection pattern suggests that tapeworms are ingested during sediment feeding in L. benedicti, which E. benedicti avoid by filter feeding. Larger L. benedicti had more Polypocephalus sp. larvae. The thoracic ganglia, which make up the largest proportion of neural tissue, contained the largest numbers of Polypocephalus sp. larvae. Intensity of Polypocephalus sp. infection was not correlated with how long L. benedicti remained above sand in behavioural tests, suggesting that Polypocephalus sp. do not manipulate the sand crabs in a way that facilitates trophic transmission of the parasite. Litopenaeus setiferus may be a primary host for Polypocephalus sp., and L. benedict may be a secondary, auxiliary host.
Parasite infection and sand coarseness increase sand crab (Emerita analoga) burrowing time
Behavioural Processes, 2011
Parasites with indirect life cycles require trophic transmission from intermediate hosts to definitive (vertebrate) hosts. Transmission may be facilitated if parasite infection alters the behavior of intermediate hosts such that they are more vulnerable to predation. Vulnerability to predation may also be influenced by abiotic factors; however, rarely are the effects of parasites and abiotic factors examined simultaneously. The swash zone of sandy beaches is a particularly harsh environment. Sand crabs (Emerita analoga) burrow rapidly in the swash zone to avoid predators and dislodgment. We examined prevalence and abundance of the acanthocephalan parasite Profilicollis altmani in sand crabs, and investigated the synergistic effects of sand grain size (an important abiotic factor), parasite infection, body size and reproductive condition on burrowing speed in females, from three California sites. More heavily parasitized crabs burrowed more slowly, making them potentially more vulnerable to predation by marine bird definitive hosts. Ovigerous females harbored more parasites than non-ovigerous females, but burrowed more quickly. All crabs burrowed slowest in the coarsest sand, and burrowing times increased with repeated testing, suggesting that it is energetically costly. Abiotic and biotic factors influence burrowing, and behavioral variation across sites may reflect the response to natural variation in these factors.
Anais da Academia Brasileira de Ciências, 2013
We investigated if the differences in density and nematode communities of intertidal sediments from two Brazilian sheltered sandy beaches were related to environmental characteristics. The upper tide level (UTL) and the low tide level (LTL) of both beaches were surveyed in January (austral summer) and June 2001 (austral winter) during low-spring tides, by collecting samples of nematodes and sediments. Differences in density between beaches, tidal level and seasons, and nematode community structure were investigated. Sediments from both beaches were composed of medium to very coarse sand. The highest nematode densities were found at the UTL, and significant differences between beaches, tidal levels and months were found. A total of 54 genera were found and the genera composition on both sheltered beaches was similar to other exposed worldwide sandy beaches. The density and structure of the nematode community at both beaches clearly varied along the spatial and temporal scales. Gravel percentage was the most important variable explaining the spatial distribution of the nematodes, determining the four sub-communities; this suggests that the sediment characteristics influence the nematode community, rather than physical hydrodynamic forces. Temperature and salinity were suggested to be important variables affecting the temporal variation.
Interactions between nematodes and their microbial enemies in coastal sand dunes
2012
8 Abstract European foredunes are almost exclusively 9 colonised by Ammophila arenaria, and both the natural 10 succession and the die-out of this plant have been linked to 11 populations of plant-parasitic nematodes (PPN). The 12 overarching aim of this study was to investigate top-down 13 control processes of PPN in these natural ecosystems 14 through comparative analyses of the diversity and 15 dynamics of PPN and their microbial enemies. Our specific 16 aims were, first, to identify and quantify PPN microbial 17 enemies in European sand dunes; second, to assess their 18 life history traits, their spatial and temporal variation in 19 these ecosystems, and third, to evaluate their control 20 potential of PPN populations. This was done by seasonal 21 sampling of a range of sites and making observations on 22 both the nematode and the microbial enemy communities 23 in rhizosphere sand. Nine different nematode microbial 24 enemies belonging to different functional groups were 25 detected in European sand dunes. Their high diversity in 26 these low productivity ecosystems could both result from 27 or lead to the lack of dominance of a particular nematode 28 genus. The distribution of microbial enemies was spatially 29 and temporally variable, both among and within sampling 30 sites. Obligate parasites, either with low host-specificity or 31 having the ability to form an environmentally resistant 32 propagule, are favoured in these ecosystems and are 33 more frequent and abundant than facultative parasites. 34 Three microbial enemies correlated, either positively or 35 negatively, with PPN population size: Catenaria spp., 36 Hirsutella rhossiliensis and Pasteuria penetrans. Micro-37 bial-enemy supported links in the food-web may be 38 involved in the control of PPN populations through indirect 39 effects. The endospore-forming P. penetrans was the most 40 successful top-down control agent, and was implicated in 41 the direct control of Meloidogyne spp. and indirect facili-42 tation of Pratylenchus spp. Overall, our findings suggest 43 strong and diverse top-down control effects on the nema-44 tode community in these natural ecosystems. 45 46
Journal of Coastal Conservation
Nematode functional traits and community structure approaches are receiving attention and being debated regarding the similarity in gained information. This work applied two nematode methods (i.e. functional traits, community structure) and sex ratios to investigate sandy beaches experiencing physical disturbances and anthropogenic stressors along the Alexandrian coast of Egypt. It is the first study to identify the Egyptian marine benthic nematodes to genus level yielding fourteen genera. This study addressed the following questions. (A) Which analyses of functional traits, community structure, or sex ratio could distinguish beaches experiencing natural disturbances from anthropogenic stressors? (B) What are the driving forces that govern nematode assemblages? Designated beaches were high pollution and energy (HPHE), high pollution but low energy (HPLE), and clean high energy (CHE). The study was conducted in March 2014, applying a stratified random sampling design and advanced mul...
The role of a dominant macrobenthic polychaete, Scolelepis squamata, in the colonisation of defaunated tropical sediments by sandy-beach nematodes was investigated and compared with a previous colonisation experiment carried out on a temperate sandy beach. Experimental cylinders, equipped with lateral windows allowing infaunal colonisation, were filled with defaunated sediment containing two treatments, with and without S. squamata. These cylinders were inserted into microcosms containing sediment with indigenous meiofauna collected from the field. The treatments were incubated in the laboratory at ambient temperature and salinity for 7, 14 and 21 days. The nematode assemblages in both treatments did not differ in composition between treatments and from the natural assemblages, suggesting that all the species were equally able to colonise the experimental cores. The presence of the polychaete did not affect the development of the nematode community composition, in contrast to the results from a previous temperate-beach experiment. However, our results did not indicate whether the difference in results was caused by the different behaviour of the polychaete specimens, or by the different composition and response of the present nematode community.
Zoosystematics and Evolution, 2016
Parasites, by definition, can affect mortality of their host, making parasitism an important biotic determinant of animal population dynamics and community structure. Reduction in the number of larger, reproductive age females in populations of the Pacific sand crab, Emerita rathbunae (Decapoda, Hippidae), was observed in studies of the helminth community of this host. The aim of this study was to determine if high abundance of the metacercaria of the trematode, Microphallus nicolli (Microphallidae), causes mortality in this host. Females of E. rathbunae were collected from four sandy beaches in Guerrero State, Mexico, and helminths were collected from each crab. An analysis of variance (Anova) was applied to these data in order to identify differences in abundance between sizes of crabs, and an analysis of covariance (Ancova) was applied to identify differences in the abundance of metacercariae between locations. Parasite-related mortality was inferred by a decrease in abundance in older hosts. Linear and polynomial regressions of mean abundance of helminths (log x+1 transformed data) vs. cephalothorax length of crabs were significant for the four populations of E. rathbunae, indicating increased mortality of older, more heavily infected female crabs and resultant removal from the population. Encapsulation and melanization of cysts by crabs was observed, indicating that an immune response by crabs also killed a portion of the cysts from subsequent exposures. Mortality of hosts through behavioral modification favoring transmission of highly infected crabs was suggested as the driving force behind this process.
New Zealand Journal of Marine and Freshwater Research , 2006
Talorchestia quoyana is the most abundant sand hopper (Amphipoda: Talitridae) on New Zealand's beaches. These supralittoral detritivores are host to a parasitic mermithid nematode, Thaumamermis zealandica. In other systems, mermithids have been found to manipulate host behaviour to facilitate the continuation of their lifecycle. The aim of the present study was to determine if the burrowing behaviour of T. quoyana showed evidence of manipulation by T. zealandica. Two studies were conducted to assess the spatial and temporal patterns in sand hopper burrowing under field and laboratory conditions. Sand hopper burrowing behaviour showed considerable variation, related to sand hopper length, sand hopper distribution, month of collection, and experimental moisture conditions. The presence of parasites was not a significant factor in determining sand hopper burrowing behaviour, a result contrary to previous laboratory findings for this system. This study illustrates the benefits of combining both field and laboratory experiments to evaluate whether or not parasites alter host behaviour.
2022
Host behaviour can be influenced by parasitic risk and infection through a variety of direct and indirect mechanisms. We can expect individuals expressing different phenotypes to also differ in the ways their behaviour is altered by parasites. We used the land snail Cepaea nemoralis, a species with various shell colour morphs differing in behaviour and physiology, as a model to study the link between parasite response and individual behaviour variation. We analysed metazoan parasite abundance and its relation to behaviour (movement and food intake) in snails from three shell morphs (from light unbanded to darker five-banded) and from two neighbouring populations from contrasted environments. Snails were parasitized by mites, trematodes and nematodes, from rarest to most frequent. We confirm that terrestrial gastropods can defend against infection by trapping parasitic nematodes in their shell. We show that nematode encapsulation can uncover past infections even when a population is ...
Estuarine Coastal and Shelf Science, 2011
The effect of an abundant sandy beach polychaete, Scolelepis squamata, on the colonisation of defaunated sediments by marine nematodes indicates that sandy beach fauna can be partially controlled by biological interactions within and across size groups. Experimental cores, equipped with windows allowing infaunal colonisation, were filled with defaunated sandy beach sediment containing two different treatments with and without S. squamata. These cores were inserted into microcosms filled with sediment with indigenous meiofauna collected from the field. The treatments were incubated in the laboratory at ambient temperature and salinity for 2, 7, 14 and 21 days, in order to follow the colonisation process of the defaunated sediments by the indigenous nematode fauna over time. Nematodes initially colonised both treatments, with abundances of up to 10% of the densities in the control; after 2 weeks, nematode densities in the cores without S. squamata surpassed the control densities. Nematode assemblages in both treatments were not species rich, and also differed in composition from the natural assemblages. The most successful colonising species, Enoplolaimus litoralis, was rare in the surrounding sediment, suggesting that colonisation was determined by species-specific characteristics such as body size, motility and feeding strategy. Initially the presence of macrofauna did not affect the nematode community composition, but after 2 weeks of the experiment, the presence of the polychaete seemed to facilitate the earlier establishment of non-opportunistic species.