Host Sea Anemones Research Articles

Proteomes of native and non-native symbionts reveal responses underpinning host-symbiont specificity in the cnidarian-dinoflagellate symbiosis.

Cellular mechanisms responsible for the regulation of nutrient exchange, immune responses, and symbiont population growth in the cnidarian-dinoflagellate symbiosis are poorly resolved, particularly with respect to the dinoflagellate symbiont. Here, we characterized proteomic changes in the native symbiont Breviolum minutum during colonization of its host sea anemone Exaiptasia diaphana ("Aiptasia"). We also compared the proteome of this native symbiont in the established symbiotic state with that of a non-native symbiont, Durusdinium trenchii. The onset of symbiosis between Aiptasia and Breviolum minutum increased the accumulation of symbiont proteins associated with the acquisition of inorganic carbon and photosynthesis, nitrogen metabolism, micro- and macronutrient starvation, suppression of host immune responses, tolerance to low pH, and management of oxidative stress. Such responses are consistent with a functional, persistent symbiosis. In contrast, D. trenchii predominantly showed elevated levels of immunosuppressive proteins, consistent with the view that this symbiont is an opportunist that forms a less beneficial, less well-integrated symbiosis with this model anemone. By adding symbiont analysis to the already known responses of the host proteome, our results provide a more holistic view of cellular processes that determine host-symbiont specificity and how differences in symbiont partners (i.e. native versus non-native symbionts) may impact the fitness of the cnidarian-dinoflagellate symbiosis.

Fauna of Anemonefishes (Pomacentridae, Amphiprioninae) and Their Host Sea Anemones (Cnidaria, Actiniaria) of the Hon Rom Coral Reefs (Southern Central Vietnam, Nha Trang Bay) and its Changes for the Period from 2003 to 2018

Fauna of Anemonefishes (Pomacentridae, Amphiprioninae) and Their Host Sea Anemones (Cnidaria, Actiniaria) of the Hon Rom Coral Reefs (Southern Central Vietnam, Nha Trang Bay) and its Changes for the Period from 2003 to 2018

Impacts of bleaching on host sea anemones and associated anemonefish in Southeast Asian coral reefs

Impacts of bleaching on host sea anemones and associated anemonefish in Southeast Asian coral reefs

Anemonefish are better taxonomists than humans

The symbiosis between giant sea anemones, algae of the family Symbiodiniaceae, and anemonefish is an iconic example of a mutualistic trio1,2. Molecular analyses have shown that giant sea anemones hosting anemonefish belong to three clades: Entacmaea, Stichodactyla, and Heteractis3,4,5 (Figure 1A). Associations among 28 species of anemonefish and 10 species of giant sea anemone hosts are complex. Some fish species are highly specialized to only one anemone species (e.g., Amphiprion frenatus with Entacmaea quadricolor), whereas others are more generalist (e.g., Amphiprion clarkii)1,2,6. Reasons for host preferences are obscured, among other things, by the lack of resolution in the giant sea anemone phylogeny. Here, we generated a transcriptomic dataset from 55 sea anemones collected from southern Japan to reconstruct these phylogenetic relationships. We observed that the bubble-tip sea anemone E. quadricolor, currently considered a single species, can be separated into at least four cryptic lineages (A-D). Surprisingly, these lineages can be precisely distinguished by observing their association with anemonefish: A. frenatus only associates with lineage D, whereas A. clarkii lives in the other three lineages.

Proteotransciptomics of the Most Popular Host Sea Anemone Entacmaea quadricolor Reveals Not All Toxin Genes Expressed by Tentacles Are Recruited into Its Venom Arsenal.

While the unique symbiotic relationship between anemonefishes and sea anemones is iconic, it is still not fully understood how anemonefishes can withstand and thrive within the venomous environment of their host sea anemone. In this study, we used a proteotranscriptomics approach to elucidate the proteinaceous toxin repertoire from the most common host sea anemone, Entacmaea quadricolor. Although 1251 different toxin or toxin-like RNA transcripts were expressed in E. quadricolor tentacles (0.05% of gene clusters, 1.8% of expression) and 5375 proteins were detected in milked venom, only 4% of proteins detected in venom were putative toxins (230), and they only represent on average 14% of the normalised protein expression in the milked venom samples. Thus, most proteins in milked venom do not appear to have a toxin function. This work raises the perils of defining a dominant venom phenotype based on transcriptomics data alone in sea anemones, as we found that the dominant venom phenotype differs between the transcriptome and proteome abundance data. E. quadricolor venom contains a mixture of toxin-like proteins of unknown and known function. A newly identified toxin protein family, Z3, rich in conserved cysteines of unknown function, was the most abundant at the RNA transcript and protein levels. The venom was also rich in toxins from the Protease S1, Kunitz-type and PLA2 toxin protein families and contains toxins from eight venom categories. Exploring the intricate venom toxin components in other host sea anemones will be crucial for improving our understanding of how anemonefish adapt to the venomous environment.

Physiological responses of the symbiotic shrimp Ancylocaris brevicarpalis and its host sea anemone Stichodactyla haddoni to ocean acidification

In this study, the physiology of symbiotic ‘peacock-tail’ shrimp Ancylocaris brevicarpalis and its host ‘Haddon's carpet’ sea anemone Stichodactyla haddoni were tested under lowered pH (7.7) and control (8.1) conditions. The biochemical responses such as digestive enzyme (AP), organic acids (lactate and succinate), oxidative damages (MDA), antioxidants metabolites/enzymes (ASC, GSH, SOD, CAT, APX, GPX, GR, POX, and PHOX), and detoxification enzyme (GST) were measured. The AP showed insignificantly reduced values in both the organisms in lowered pH conditions compared to control indicating the effect of abiotic stress. The hierarchical clustering analysis indicated low MDA in sea anemone can be explained by higher POX, APX, GR, ASC, and GSH levels compared to shrimps. However, the detoxification enzyme GST showed less activity in sea anemones compared to shrimps. The results suggest that A. brevicarpalis and sea anemone S. haddoni may have deleterious effects when exposed to short-term acidification stress.

Habitat limits the poleward establishment of anemonefishes in a climate change hotspot

Climate change is modifying marine species' distribution with consequences for the structure and function of ecosystems. The warming and strengthening East Australian Current (EAC) is driving the tropicalisation of subtropical marine ecosystems through changing overwinter survival of tropical species. However, this can be complex for obligate symbionts, such as anemonefishes. Here, we documented fine-scale temporal changes in the density of anemonefishes and assessed the influence of latitude, temperature, and host sea anemone availability. Juvenile, subadult and adult Amphiprion akindynos and Amphiprionlatezonatus occurred at all study locations: North Solitary Island (equatorward), South Solitary Island, and Fish Rock (poleward). While the sea anemone Heteractis crispa was readily available at Fish Rock, we found that a lack of another sea anemone Entacmaea quadricolor hindered the establishment of adult A. akindynos and A. latezonatus populations. Minimum water temperature was also a bottleneck for the tropical anemonefish A. akindynos but not for the subtropical A. latezonatus. Our findings suggest anemonefishes are capable of contributing to the tropicalisation of the east coast of Australia. However, poleward establishment is currently limited by the absence of the preferred host sea anemone.

Large host anemones can be shelters of a diverse assemblage of fish species, not just anemonefish.

The mutualistic relationships between anemonefish (Amphiprion; Pomacentridae) and host sea anemones are well known, but host anemones are also used as shelter by damselfish (Pomacentridae), wrasses (Labridae) and cardinalfish (Apogonidae). The threespot dascyllus Dascyllus trimaculatus (Pomacentridae) is known to live on or near host anemones in their immature phase. Nonetheless, detailed studies on the use of host anemones by other fish species have not yet been conducted. To understand the factors that influence the use of host anemones by other fish species, this study investigated the fish biota around host anemones in the Ryukyu Archipelago. Other than Amphiprion spp. and D. trimaculatus, 10 additional species of fish (9 species of damselfish and 1 species of cardinalfish) were confirmed to temporarily use host anemones as shelter, and five species of wrasse including Labroides dimidiatus came to clean anemonefish. Logistic regression analyses (independent variable: presence or absence of other species of fish; dependent variables: anemonefish aggressiveness, size of host anemone, number of D. trimaculatus) indicated that the size of host anemones is important for the presence of fish, both in species using the anemone as temporary shelter and in cleaner species. Large host anemones can provide shelter and food resources for other species of coral reef fish as well as for anemonefish.

Ocean temperature, but not acidification, causes sea anemone bleaching under a near-future climate scenario

Climate change is causing ocean temperature and partial pressure of carbon dioxide (pCO2) to increase. For sea anemones that have Symbiodiniaceae, high temperatures induce bleaching, whereas rises in pCO2 can enhance photosynthesis and increase host growth and abundance. It is, however, not clear how the interaction of these two stressors impacts sea anemones that provide habitat for anemonefishes. Here, we investigated the bleaching response of the sea anemone Entacmaea quadricolor, under four conditions: (i) current temperature and current pCO2 (control); (ii) future pCO2; (iii) future temperature; and (iv) future temperature and future pCO2. After 16 days of exposure, future temperature, but not pCO2 nor their interaction, significantly reduced the Symbiodiniaceae density and total chlorophyll Symbiodiniaceae cell−1. Colour score was lower in the sea anemones exposed to future temperature than current temperature from day 4 onwards. In contrast, total chlorophyll symbiont cell−1 increased in the future temperature treatments, and light-adapted effective quantum yield remained similar in all treatments. Although pCO2 had no impact within the time frame of our experiment, the predicted future temperature induced bleaching in E. quadricolor. As bleaching events increase in frequency and severity, this will likely impact the abundance of host sea anemones and their symbiotic anemonefishes.

Anemonefish facilitate bleaching recovery in a host sea anemone

Ocean warming is causing the symbioses between cnidarians and their algal symbionts to breakdown more frequently, resulting in bleaching. For sea anemones, nutritional benefits derived from hosting anemonefishes increase their algal symbiont density. The sea anemone-anemonefish relationship could, therefore, facilitate bleaching recovery. To test this, bleached and unbleached sea anemones, both with and without anemonefish, were monitored in the laboratory. At the start of our experiment, algal symbiont density and colour score were lower in the bleached than unbleached sea anemones, whereas total chlorophyll remained similar. After 106 days, bleached sea anemones with anemonefish had an algal symbiont density and colour score equal to the controls (unbleached sea anemones and without anemonefish), indicating recovery had occurred. Furthermore, total chlorophyll was 66% higher in the bleached sea anemones with anemonefish than the controls. In contrast, recovery did not occur for the bleached sea anemones without anemonefish as they had 78% fewer algal symbionts than the controls, and colour score remained lower. Unbleached sea anemones with anemonefish also showed positive changes in algal symbiont density and total chlorophyll, which increased by 103% and 264%, respectively. Consequently, anemonefishes give their host sea anemones a distinct ecological advantage by enhancing resilience to bleaching, highlighting the benefits of symbioses in a changing climate.

Symbiont population control by host-symbiont metabolic interaction in Symbiodiniaceae-cnidarian associations

In cnidarian-Symbiodiniaceae symbioses, algal endosymbiont population control within the host is needed to sustain a symbiotic relationship. However, the molecular mechanisms that underlie such population control are unclear. Here we show that a cnidarian host uses nitrogen limitation as a primary mechanism to control endosymbiont populations. Nitrogen acquisition and assimilation transcripts become elevated in symbiotic Breviolum minutum algae as they reach high-densities within the sea anemone host Exaiptasia pallida. These same transcripts increase in free-living algae deprived of nitrogen. Symbiotic algae also have an elevated carbon-to-nitrogen ratio and shift metabolism towards scavenging nitrogen from purines relative to free-living algae. Exaiptasia glutamine synthetase and glutamate synthase transcripts concomitantly increase with the algal endosymbiont population, suggesting an increased ability of the host to assimilate ammonium. These results suggest algal growth and replication in hospite is controlled by access to nitrogen, which becomes limiting for the algae as their population within the host increases.

Comparative phylogeography of three host sea anemones in the Indo‐Pacific

AbstractAimThe mutualistic relationship between anemones and anemonefishes is one of the most iconic examples of symbiosis. However, while anemonefishes have been extensively studied in terms of genetic connectivity, such information is lacking entirely for host sea anemones. Here, we provide the first information on the broad‐scale population structure and phylogeographical patterns of three species of host sea anemone, Heteractis magnifica, Stichodactyla mertensii and Entacmaea quadricolor. We evaluate if there is concordance in genetic structure across several distinct biogeographical areas within the Indo‐Pacific region and to what extent the observed patterns may concur with those found for anemonefishes.LocationIndo‐Pacific, including the Red Sea.TaxonHeteractis magnifica, S. mertensii and E. quadricolorMethodsMicrosatellite markers and a combination of statistical methods including Bayesian clustering, isolation by distance (IBD), analysis of molecular variance (AMOVA) and principal components analysis (PCA) were used to determine population structure. The congruence among distance matrices (CADM) method was used to assess similarity in spatial genetic patterns among species.ResultsSignificant population structure was identified in the three host anemone species. Each species is likely composed of at least two genetic clusters corresponding to two biogeographical regions, the Red Sea and the rest of the Indo‐Pacific. Two of the three anemone species seem to be experiencing admixture where the two main clusters overlap (the Maldives). IBD analyses in the Red Sea revealed differences in gene flow among species, suggesting more limited dispersal potential for E. quadricolor than for S. mertensii and H. magnifica. Clonality is documented in S. mertensii for the first time.Main conclusionsThis research documents the genetic population structure for three ecologically important host sea anemones across the Indo‐Pacific and provides valuable insights regarding their biogeography and evolution. Specifically, we found high levels of genetic divergence between populations across different biogeographical regions, suggesting different evolutionary lineages within species. At the same time, common geographical overlap of population structures suggests similar evolutionary histories among all three species. Interestingly, the observed patterns are congruent to some extent with structure reported for several anemonefish species, reflecting their close ecological association.

Social behavior of the Pederson cleaner shrimp Ancylomenes pedersoni (Chace, 1958) (Decapoda: Caridea: Palemonidae) in the Caribbean Sea: size- and gender-based dominance hierarchy

AbstractSocial interactions among Pederson cleaner shrimp Ancylomenes pedersoni (Chace, 1958), an associate of sea anemones, likely affect cleaning services to reef fishes, but major aspects of their social group structure and behavior remain unknown. We hypothesized that Pederson shrimp form dominance hierarchies expressed through size- and gender-based behavioral interactions. Observation of 116 shrimp on coral reefs at St. Thomas, US Virgin Islands, revealed that they formed social groups of ~3 or 4 individuals (range 1–9) per host sea anemone, as a mix of large females, medium-size males, and/or small juveniles. Social groups were not rigidly size-structured, in that body size ratio between adjacent individuals did not differ significantly from random. Individuals, however, were spatially structured such that distance between shrimp and the tentacles of the host anemone decreased significantly with shrimp body size; large individuals occupied the anemone tentacle crown, whereas smaller shrimp perched on reef or sand substrates adjacent to the anemone. During laboratory experiments, shrimp exhibited five types of exploitation competition behaviors toward client fish models (signal, approach, clean, no response, retreat), and four types of interference competition behaviors toward conspecific shrimp (approach, attack, no response, retreat). Large females more frequently signaled toward, approached, and cleaned fish models than did males and juveniles, which did not respond or retreated. Females also approached and attacked conspecifics more than did males and juveniles, which retreated at frequencies that increased with decreasing body size. We conclude that Pederson shrimp form gender and size-based hierarchies in which large females monopolize food resources (ectoparasites on client fishes), and interfere with resource access by smaller males and juveniles. These behaviors cause them to spatially partition microhabitats on anemones, and hypothetically could lead to males and juveniles dispersing among anemones more frequently than females. These shrimp social interactions may thus enhance spatial and temporal variation among cleaning stations, with consequences for the health and mobility of reef fishes.

Nickel uptake in Symbiodynium spp. and host cnidarian -assessment using the model cnidarian Exaiptasia pallida

Start Nickel (Ni) is common marine pollutant and derived from discharge of industries, mining and agriculture. Elevated Ni concentrations, could be harmful the organisms in marine environment such as corals reef. The sea anemones Exaiptasia pallida has been widely used for toxicity tests in the laboratory because it is easy to maintain and culture in contained aquarium conditions. To understand the pathway of uptake and storage of elevated Ni between the sea anemone host and symbiotic algae, and the model sea anemone E. pallida was exposed to three different Ni concentrations (500 xg/L, 1000 xg/L, 2000 xg/L) and control treatment over 9 days and 18 days. Ni accumulation was assessed in both the host anemone tissues and the Symbiodinium spp. The concentration of Ni was measured using Perkin Elmer NexION 300D ICPMS (Inductively Couple Plasma Mass Spectrophotometry) after sampel digestion. The statistical analysis was completed using R version 3.5.0 (R core team 2013) R Foundation for Statistical Computing, Vienne, Austria. The model was chosen by Akaike Information Criterion (AIC) after to comparing between model options. Shapiro-Wilks test was used to verify the normal distribution of the date set to be analysed.The overall result showed the accumulation of nickel was highest in Symbiodinium spp. (212.62 + 50.12 mg/Kg) after a 9 days exposure period in concentration 2000 xg/L while 18 days exposure period was less ( 129.66 + 31,94 mg/Kg) in concentration 2000 xg/L. The lower uptake of Ni in Symbiodinium spp. in the longer exposure time of 18 days compare to 9 days exposure might be due to the ability of Symbiodinium spp. to release the Ni through their metabolism or the Ni dose may have inhibited normal function of the algae, although the accumulation of both times period was significantly higher than the control treatments. Meanwhile, host anemones accumulated 77.43 + 6.28 mg/Kg Ni over 9 days exposure period and the 2000 xg/L treatment and increased after 18 days exposure in concentration 2000 xg/L (45.54 + 4.12 mg/Kg).The result of these finding highlight the importance of understanding the metal accumulation in host and cnidarian. This is particularly important if these species are used in biomonitoring studies where bleaching may occur due to stress, but may in effect be a depuration pathway for metal load, masking the biological uptake and interaction between metal and organisms.

Global Shifts in Gene Expression Profiles Accompanied with Environmental Changes in Cnidarian-Dinoflagellate Endosymbiosis.

Stable endosymbiotic relationships between cnidarian animals and dinoflagellate algae are vital for sustaining coral reef ecosystems. Recent studies have shown that elevated seawater temperatures can cause the collapse of their endosymbiosis, known as ‘bleaching’, and result in mass mortality. However, the molecular interplay between temperature responses and symbiotic states still remains unclear. To identify candidate genes relevant to the symbiotic stability, we performed transcriptomic analyses under multiple conditions using the symbiotic and apo-symbiotic (symbiont free) Exaiptasia diaphana, an emerging model sea anemone. Gene expression patterns showed that large parts of differentially expressed genes in response to heat stress were specific to the symbiotic state, suggesting that the host sea anemone could react to environmental changes in a symbiotic state-dependent manner. Comparative analysis of expression profiles under multiple conditions highlighted candidate genes potentially important in the symbiotic state transition under heat-induced bleaching. Many of these genes were functionally associated with carbohydrate and protein metabolisms in lysosomes. Symbiont algal genes differentially expressed in hospite encode proteins related to heat shock response, calcium signaling, organellar protein transport, and sugar metabolism. Our data suggest that heat stress alters gene expression in both the hosts and symbionts. In particular, heat stress may affect the lysosome-mediated degradation and transportation of substrates such as carbohydrates through the symbiosome (phagosome-derived organelle harboring symbiont) membrane, which potentially might attenuate the stability of symbiosis and lead to bleaching-associated symbiotic state transition.

Phylogenetic relationships among the clownfish-hosting sea anemones

The clownfish-sea anemone symbiosis has been a model system for understanding fundamental evolutionary and ecological processes. However, our evolutionary understanding of this symbiosis comes entirely from studies of clownfishes. A holistic understanding of a model mutualism requires systematic, biogeographic, and phylogenetic insight into both partners. Here, we conduct the largest phylogenetic analysis of sea anemones (Order Actiniaria) to date, with a focus on expanding the biogeographic and taxonomic sampling of the 10 nominal clownfish-hosting species. Using a combination of mtDNA and nuDNA loci we test (1) the monophyly of each clownfish-hosting family and genus, (2) the current anemone taxonomy that suggests symbioses with clownfishes evolved multiple times within Actiniaria, and (3) whether, like the clownfishes, there is evidence that host anemones have a Coral Triangle biogeographic origin. Our phylogenetic reconstruction demonstrates widespread poly- and para-phyly at the family and genus level, particularly within the family Stichodactylidae and genus Stichodactyla, and suggests that symbioses with clownfishes evolved minimally three times within sea anemones. We further recover evidence for a Tethyan biogeographic origin for some clades. Our data provide the first evidence that clownfish and some sea anemone hosts have different biogeographic origins, and that there may be cryptic species of host anemones. Finally, our findings reflect the need for a major taxonomic revision of the clownfish-hosting sea anemones.

First draft genome of an iconic clownfish species (Amphiprion frenatus).

Clownfishes (or anemonefishes) form an iconic group of coral reef fishes, principally known for their mutualistic interaction with sea anemones. They are characterized by particular life history traits, such as a complex social structure and mating system involving sequential hermaphroditism, coupled with an exceptionally long lifespan. Additionally, clownfishes are considered to be one of the rare groups to have experienced an adaptive radiation in the marine environment. Here, we assembled and annotated the first genome of a clownfish species, the tomato clownfish (Amphiprion frenatus). We obtained 17,801 assembled scaffolds, containing a total of 26,917 genes. The completeness of the assembly and annotation was satisfying, with 96.5% of the Actinopterygii Benchmarking Universal Single-Copy Orthologs (BUSCOs) being retrieved in A.frenatus assembly. The quality of the resulting assembly is comparable to other bony fish assemblies. This resource is valuable for advancing studies of the particular life history traits of clownfishes, as well as being useful for population genetic studies and the development of new phylogenetic markers. It will also open the way to comparative genomics. Indeed, future genomic comparison among closely related fishes may provide means to identify genes related to the unique adaptations to different sea anemone hosts, as well as better characterize the genomic signatures of an adaptive radiation.

НАХОДКА БОЛЬШОЙ КЛОНАЛЬНОЙ ГРУППЫ ОБЛИГАТНО СИМБИОТИЧЕСКОЙ АКТИНИИ ENTACMAEA QUADRICOLOR БЕЗ РЫБ-СИМБИОНТОВ – ВЛИЯНИЕ УСЛОВИЙ СРЕДЫ

The large clonal group of the obligate host sea anemone Entacmaea quadricolor (Leuckart in Ruppell et Leuckart, 1828) (Anthozoa, Actiniaria, Actiniidae) was found at the station with coordinates 20°44’09.0’’ N and 107o08’55.8’’ E in the water area of Cat Ba Islands in the Tonkin Gulf. This clonal group was located on stony bottom (surrounded by sands) at a depth of 4 m, had an area of about 15 m², consisted of hundreds of host sea anemones, but was not inhabited by anemonefishes. Large clonal groups of host sea anemone E. quadricolor uninhabited by anemonefishes were not previously noted in other parts of the coastal waters of Vietnam. Comparison of the investigated water area with the waters of Hong Kong showed their similarity in temperature and hydrological parameters with more turbidity in Cat Ba. In the waters of Hong Kong huge fields of host sea anemone E. quadricolor are marked by an extremely low density of anemonefishes: 0.07–0.26 fishes per m². From this it follows that the environmental conditions in the waters of Hong Kong and especially of Cat Ba Islands are extreme for the habitat of anemonefishes, even for Amphiprion clarkii. Probably single specimens of anemonefishes can be found in Cat Ba region when more extended studies of large clonal groups of the host sea anemone E. quadricolor are curried out.

About the Cover

Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverThe cover image is of a Pederson cleaner shrimp, Ancylomenes pedersoni, perched near its host sea anemone on a patch reef at St. Thomas, U.S. Virgin Islands. Individuals of this species are major cleaners of ectoparasites from reef fishes in the Caribbean Sea, yet key aspects of their life history and population structure remain unknown.On pages 190–205, J. A. Gilpin and N. E. Chadwick reveal that the reproductive biology of this shrimp supports predictive models about the evolution of life-history strategies in symbiotic crustaceans. The results also provide a scientific basis for the conservation management of this ecologically important Caribbean reef invertebrate, which is in high demand for the ornamental aquarium trade.Credits: Photo, Jessica A. Gilpin, Auburn University. Cover design, Jeannie Harrell, University of Chicago Press. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 233, Number 3December 2017 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/697756 © 2017 by The University of Chicago. All rights reserved.PDF download Crossref reports no articles citing this article.

Life-History Traits and Population Structure of Pederson Cleaner Shrimps Ancylomenes pedersoni.

Cleaner organisms perform key functional roles in reducing rates of parasitism in marine communities. Pederson cleaner shrimps Ancylomenes pedersoni are major cleaners of reef fishes in the tropical western Atlantic and form obligate symbioses with host sea anemones. Information about their life-history traits would contribute to understanding how symbiosis impacts life-history evolution in crustaceans, but little is known about patterns of growth and reproduction in this anemone shrimp. We quantified growth, sexual reproduction, senescence, and mortality in individuals of A. pedersoni under laboratory conditions and their abundance and population size structure on coral reefs in St. Thomas, U.S. Virgin Islands. Von Bertalanffy growth curves were fitted to the data to determine age-size relationships, and the Beverton-Holt model was used to estimate mortality rates and size at maximum yield. Individuals grew rapidly when young, then slowed their growth after reaching sexual maturity at ~6 months. Individuals were gonochoric, with males attaining significantly smaller body sizes and shorter life spans than did females. Prior to death at <2 years, members of both genders exhibited senescence during which they ceased reproducing, shrank (females only), and decreased their activity levels over ~1-4 weeks. Field populations were abundant and composed mostly of juveniles during both years examined. Populations appeared to be stable but highly dynamic in terms of individuals, reaching maximum yield at 4 months of age. We conclude that obligate symbiosis with large sea anemones and cleaner mutualism with reef fishes both contribute to explaining aspects of the life history of Pederson shrimps, especially their apparent mating system of pure-search polygynandry. This life-history information also provides a scientific basis for sustainable fishery management and aquaculture of this key coral reef organism.