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M. J. Kramer - One of the best experts on this subject based on the ideXlab platform.
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Foraging and microhabitat use by Crustacean-feeding wrasses on coral reefs
Marine Ecology Progress Series, 2016Co-Authors: M. J. Kramer, Orpha Bellwood, David R. BellwoodAbstract:Crustaceans are an important component of coral reef ecosystems, occupying a broad range of microhabitats, but achieving the greatest biomass in dead coral and coral rubble. These 2 microhabitats are therefore hypothesised to be focal foraging locations for Crustacean-feeding fishes. The present study investigated the relationship between foraging in wrasses (Labridae), a major group of Crustacean predators, and 5 major microhabitats on a coral reef: live coral, dead coral, coral rubble, sand and the epilithic algal matrix (EAM). Although the greatest biomass of Crustaceans typically occurs in dead coral and coral rubble, Crustacean-feeding wrasses displayed positive selection for a more diverse range of microhabitats. In contrast, sand and live coral were not positively selected by any taxa. The relationships between Crustacean predators and their prey appear to be more complicated than previously assumed, and may be mediated by habitat structure, preferred prey, predation risk and behavioural and morphological adaptations.
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Crustacea on coral reefs: habitat associations and trophic relationships
2015Co-Authors: M. J. KramerAbstract:Crustaceans are one of the most widespread and speciose marine groups, performing key ecological roles to many ecosystems. On coral reefs they are part of one of the most diverse and complex ecosystems on Earth. It would be reasonable to expect that Crustaceans are important coral reef organisms, yet the body of work concerning coral reef Crustaceans pales in comparison to other popular groups, such as fishes and corals. To rectify this, I investigated the importance of Crustaceans as a component of the coral reef faunal assemblage, quantifying their distribution and abundance across a range of reef microhabitats, comparing the tropical assemblage to the better-understood temperate assemblage, and examining the role of reef Crustacea as a dietary resource for fishes. To determine the community structure, abundance, biomass and productivity of benthic Crustacea on a typical coral reef, I investigated 5 major microhabitats: dead coral, coral rubble, sand, epilithic algal matrix (EAM) and fine-branching live coral at Lizard Island, a mid-shelf reef on the Great Barrier Reef, Australia (Chapter 2). Crustacean communities differed significantly among habitats. Dead coral was by far the most important microhabitat type in terms of Crustacean abundance (7838 ± 628 ind. 100 cm⁻², mean± SE), biomass (0.75 ± 0.13 g m⁻², wet weight) and estimated productivity (0.92 ± 0.13g100 cm⁻² yr⁻¹ ash-free dry weight). These values were 2 to 3 orders of magnitude greater than those for the least important habitats (EAM and fine-branching live coral). The average Crustacean body length was just 0.79 ± 0.32 mm, largely due to the dominance of relatively small harpacticoid copepods. In contrast, decapods exhibited very low abundances, but yielded the greatest biomass and productivity and were particularly abundant in dead coral and coral rubble. The results highlighted the importance of small Crustaceans and dead coral microhabitats as valuable contributors to the trophic structure of coral reefs. Although it is well established that fish, coral and algal assemblages vary across large spatial scales, very little is known of the differences in Crustacean assemblages across similar scales. To determine whether Crustaceans had similar spatial patterns to other reef organisms, I investigated the EAM cryptofaunal community, dominated by Crustacea, at three locations on the Great Barrier Reef: two inner shelf locations - Orpheus Island and the Turtle Island group - and a mid-shelf location, Lizard Island (Chapter 3). Although the EAM appears to be a relatively simple and consistent habitat, significant differences in cryptofaunal assemblages were found between locations. EAM assemblages from Orpheus Is land were markedly different to those from the Turtle Island group and Lizard Is land. This appears to be a function of the sediment profile (grain size >60 μm) at Orpheus Island, as many cryptofaunal taxa displayed a positive relationship with sediment volume. However, sediment volumes did not differ significantly between the three locations, highlighting the possibility of cyclonic activity affecting the sediment profile at Orpheus Island in the months preceding the study, in addition to the nutrient input from major terrigenous sources. The results show that EAM cryptofaunal assemblages are not uniform across the Great Barrier Reef and suggest that dissolved nutrients, sediment loads and distance from river systems may be significant drivers of cryptobenthic faunal compositions. Tropical and temperate marine habitats have long been recognised as fundamentally different systems; yet, comparative studies are rare, particularly for small organisms such as Crustacea. I investigated the ecological attributes (abundance, biomass and productivity) of benthic Crustacea in selected microhabitats from a tropical and a temperate location, revealing marked differences in the structure of Crustacean assemblages (Chapter 4). In general, microhabitats from the tropical location (dead coral, the EAM and sand) supported high abundances of small individuals (mean size = 0.53 mm vs. 0.96 mm in temperate microhabitats), whilst temperate microhabitats (the brown seaweed Carpophyllum sp., coralline turf and sand) had substantially greater biomasses of Crustaceans and higher estimated productivity rates. In both locations, the most important microhabitats for Crustaceans (per unit area) were complex structures: tropical dead coral and temperate Carpophyllum sp. It appears that the differences between microhabitats are largely driven by the size and abundance of key Crustacean groups. Temperate microhabitats have a higher proportion of relatively large Peracarida (Amphipoda and Isopoda), whereas tropical microhabitats are dominated by small detrital and microalgal feeding Crustaceans (i.e. harpacticoid copepods and ostracods). These differences indicate the vulnerability of tropical systems, especially to the loss of complex benthic structures and the associated Crustacean assemblages as a result of habitat degradation. Crustaceans are one of the most influential groups in aquatic trophic networks by providing a major connection between primary production and higher consumers. Although coral reefs support a high diversity and abundance of Crustaceans, and Crustacean predators, their trophic interrelationships remain unclear. Using predator gut content analyses, I investigated trophic relationships between Crustacea and adult fishes of the family Labridae, which are one of the most abundant and diverse families of marine Crustacean predators (Chapter 5). Crustaceans were present within the guts of 93 % of the 30 wrasse genera investigated. I found a distinct division between micro- and macro-Crustacean predators: wrasses 90 mm SL displayed a predominantly macro - Crustacean diet. Notably, micro-Crustacean predators tended to specialise on certain Crustacean taxa, whereas macro-Crustacean predators consumed mostly brachyurans. My findings highlight complex patterns of feeding diversity within Crustacean predators that prompt a more detail-oriented approach to defining the role of Crustacean-feeding fishes in coral reef trophodynamics. Having established Crustacea as an important component in coral reef ecosystems, occupying a broad range of coral reef microhabitats, with the greatest biomass in dead coral and coral rubble, I investigated the relationship between foraging in wrasses and the major reef microhabitats occupied by Crustacea (Chapter 6). Although the greatest biomass of Crustaceans is in dead coral and coral rubble, Crustacean-feeding wrasses displayed strong selection for a broader range of microhabitats. Of the 14 macro Crustacean predators, only 6 selectively foraged in dead coral or coral rubble. The 10 micro-Crustacean predators likewise displayed a wide range of microhabitat fo raging associations, reflecting specific prey type preferences. The relationships between Crustacean predators and their prey appear to be more complicated than previously assumed, and may be mediated by other morphological and behavioural factors. This thesis represents an important contribution to the relatively new, emerging field of coral reef Crustacean ecology. By establishing key baseline information about the contribution of Crustaceans to the overall coral reef faunal assemblage, I have confirmed the long-held assumptions that Crustaceans are highly abundant and potentially very important on coral reefs. However, Crustacean assemblages differ considerably across large spatial scales due to local environmental factors. I also present the first tropical-temperate comparison of Crustaceans within comparable microhabitats, which has given a new perspective on the trophic functioning of each ecosystem. Importantly, Crustaceans are a major component of the diet of coral reef fishes; wrasses are a key example and provide evidence for a trophic division within Crustacean-feeding taxa. However, the relationship between Crustaceans and their fish predators appears to be complex, mediated by various factors including microhabitat, fish morphology and behaviour. Crustaceans have often been perceived as a group of organisms that are simply 'present' on coral reefs, yet this thesis demonstrates that their importance in reef trophodynamics cannot be underestimated. Crustacea have a pivotal role in coral reef ecology.
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Refining the invertivore: diversity and specialisation in fish predation on coral reef Crustaceans
Marine Biology, 2015Co-Authors: M. J. Kramer, Orpha Bellwood, Christopher J. Fulton, David R. BellwoodAbstract:Crustaceans are one of the most influential groups in aquatic trophic networks by providing a major connection between primary production and higher consumers. Although coral reefs support a high diversity and abundance of Crustaceans and Crustacean predators, their trophic interrelationships remain unclear. Using predator gut content analyses, we investigated trophic relationships between Crustacea and adult fishes of the family Labridae, which are one of the most abundant and diverse families of marine Crustacean predators. Crustaceans were present within the guts of 93 % of the 30 wrasse genera investigated. We found a distinct division between micro- and macro-Crustacean predators: wrasses 90 mm SL displayed a predominantly macro-Crustacea diet. Notably, micro-Crustacean predators tended to specialise on certain Crustacean taxa, whereas macro-Crustacean predators consumed mostly brachyurans. Our findings highlight complex patterns of feeding diversity within Crustacean predators that prompt a more nuanced approach to defining the role of Crustacean-feeding fishes in coral reef trophodynamics.
David R. Bellwood - One of the best experts on this subject based on the ideXlab platform.
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Foraging and microhabitat use by Crustacean-feeding wrasses on coral reefs
Marine Ecology Progress Series, 2016Co-Authors: M. J. Kramer, Orpha Bellwood, David R. BellwoodAbstract:Crustaceans are an important component of coral reef ecosystems, occupying a broad range of microhabitats, but achieving the greatest biomass in dead coral and coral rubble. These 2 microhabitats are therefore hypothesised to be focal foraging locations for Crustacean-feeding fishes. The present study investigated the relationship between foraging in wrasses (Labridae), a major group of Crustacean predators, and 5 major microhabitats on a coral reef: live coral, dead coral, coral rubble, sand and the epilithic algal matrix (EAM). Although the greatest biomass of Crustaceans typically occurs in dead coral and coral rubble, Crustacean-feeding wrasses displayed positive selection for a more diverse range of microhabitats. In contrast, sand and live coral were not positively selected by any taxa. The relationships between Crustacean predators and their prey appear to be more complicated than previously assumed, and may be mediated by habitat structure, preferred prey, predation risk and behavioural and morphological adaptations.
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Refining the invertivore: diversity and specialisation in fish predation on coral reef Crustaceans
Marine Biology, 2015Co-Authors: M. J. Kramer, Orpha Bellwood, Christopher J. Fulton, David R. BellwoodAbstract:Crustaceans are one of the most influential groups in aquatic trophic networks by providing a major connection between primary production and higher consumers. Although coral reefs support a high diversity and abundance of Crustaceans and Crustacean predators, their trophic interrelationships remain unclear. Using predator gut content analyses, we investigated trophic relationships between Crustacea and adult fishes of the family Labridae, which are one of the most abundant and diverse families of marine Crustacean predators. Crustaceans were present within the guts of 93 % of the 30 wrasse genera investigated. We found a distinct division between micro- and macro-Crustacean predators: wrasses 90 mm SL displayed a predominantly macro-Crustacea diet. Notably, micro-Crustacean predators tended to specialise on certain Crustacean taxa, whereas macro-Crustacean predators consumed mostly brachyurans. Our findings highlight complex patterns of feeding diversity within Crustacean predators that prompt a more nuanced approach to defining the role of Crustacean-feeding fishes in coral reef trophodynamics.
Steffen Harzsch - One of the best experts on this subject based on the ideXlab platform.
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Crustacean olfactory systems: A comparative review and a Crustacean perspective on olfaction in insects.
Progress in neurobiology, 2017Co-Authors: Steffen Harzsch, Jakob KriegerAbstract:Abstract Malacostracan Crustaceans display a large diversity of sizes, morphs and life styles. However, only a few representatives of decapod taxa have served as models for analyzing Crustacean olfaction, such as crayfish and spiny lobsters. Crustaceans bear multiple parallel chemosensory pathways represented by different populations of unimodal chemosensory and bimodal chemo- and mechanosensory sensilla on the mouthparts, the walking limbs and primarily on their two pairs of antennae. Here, we focus on the olfactory pathway associated with the unimodal chemosensory sensilla on the first antennal pair, the aesthetascs. We explore the diverse arrangement of these sensilla across malacostracan taxa and point out evolutionary transformations which occurred in the central olfactory pathway. We discuss the evolution of chemoreceptor proteins, comparative aspects of active chemoreception and the temporal resolution of Crustacean olfactory system. Viewing the evolution of Crustacean brains in light of energetic constraints can help us understand their functional morphology and suggests that in various Crustacean lineages, the brains were simplified convergently because of metabolic limitations. Comparing the wiring of afferents, interneurons and output neurons within the olfactory glomeruli suggests a deep homology of insect and Crustacean olfactory systems. However, both taxa followed distinct lineages during the evolutionary elaboration of their olfactory systems. A comparison with insects suggests their olfactory systems o especially that of the vinegar fly o to be superb examples for “economy of design”. Such a comparison also inspires new thoughts about olfactory coding and the functioning of malacostracan olfactory systems in general.
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Engrailed-like immunoreactivity in the embryonic ventral nerve cord of the Marbled Crayfish (Marmorkrebs)
Invertebrate Neuroscience, 2008Co-Authors: Kathia Fabritius-vilpoux, Sonja Bisch-knaden, Steffen HarzschAbstract:The homeobox transcription factor Engrailed is involved in controlling segmentation during arthropod germ band formation but also in establishing individual neuronal identities during later embryogenesis. In Crustacea, most studies analysing the expression of Engrailed so far have focussed on its function as segment polarity gene. In continuation to these previous studies, we analysed the neuronal expression of the Engrailed protein by immunohistochemistry in the embryonic nerve cord of a parthenogenetic Crustacean, the Marbled Crayfish (Marmorkrebs). We paid particular attention to the individual identification of Engrailed expressing putative neuroblasts in the crayfish embryos. Engrailed positive cells in the neuroectoderm were counted, measured and mapped from 38 to 65% of embryonic development. That way, several Engrailed positive putative neuroblasts and putative neurons were identified. Our findings are compared with earlier studies on Engrailed expression during germ band formation in Crustacea. Recent data on neurogenesis in an amphipod Crustacean have provided compelling evidence for the homology of several identified neuroblasts between this amphipod and insects. The present report may serve as a basis to explore the question if during Crustacean neurogenesis additional communalities with insects exist.
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Muscle precursor cells in the developing limbs of two isopods (Crustacea, Peracarida): an immunohistochemical study using a novel monoclonal antibody against myosin heavy chain
Development Genes and Evolution, 2008Co-Authors: Sabine Kreissl, Amy Uber, Steffen HarzschAbstract:In the hot debate on arthropod relationships, Crustaceans and the morphology of their appendages play a pivotal role. To gain new insights into how arthropod appendages evolved, developmental biologists recently have begun to examine the expression and function of Drosophila appendage genes in Crustaceans. However, cellular aspects of Crustacean limb development such as myogenesis are poorly understood in Crustaceans so that the interpretative context in which to analyse gene functions is still fragmentary. The goal of the present project was to analyse muscle development in Crustacean appendages, and to that end, monoclonal antibodies against arthropod muscle proteins were generated. One of these antibodies recognises certain isoforms of myosin heavy chain and strongly binds to muscle precursor cells in malacostracan Crustacea. We used this antibody to study myogenesis in two isopods, Porcellio scaber and Idotea balthica (Crustacea, Malacostraca, Peracarida), by immunohistochemistry. In these animals, muscles in the limbs originate from single muscle precursor cells, which subsequently grow to form multinucleated muscle precursors. The pattern of primordial muscles in the thoracic limbs was mapped, and results compared to muscle development in other Crustaceans and in insects.
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embryonic development of the histaminergic system in the ventral nerve cord of the marbled crayfish marmorkrebs
Tissue & Cell, 2008Co-Authors: Verena Rieger, Steffen HarzschAbstract:The embryonic development of neurotransmitter systems in Crustaceans so far is poorly understood. Therefore, in the current study we monitored the ontogeny of histamine-immunoreactive neurons in the ventral nerve cord of the Marbled Crayfish, an emerging Crustacean model system for developmental studies. The first histaminergic neurons arise around 60% of embryonic development, well after the primordial axonal scaffold of the ventral nerve cord has been established. This suggests that histaminergic neurons do not serve as pioneer neurons but that their axons follow well established axonal tracts. The developmental sequence of the different types of histaminergic neurons is charted in this study. The analysis of the histaminergic structures is also extended into adult specimens, showing a persistence of embryonic histaminergic neurons into adulthood. Our data are compared to the pattern of histaminergic neurons in other Crustaceans and discussed with regard to our knowledge on other aspects of neurogenesis in Crustacea. Furthermore, the possible role of histaminergic neurons as characters in evolutionary considerations is evaluated.
Jens Brockmeyer - One of the best experts on this subject based on the ideXlab platform.
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New High-Performance Liquid Chromatography Coupled Mass Spectrometry Method for the Detection of Lobster and Shrimp Allergens in Food Samples via Multiple Reaction Monitoring and Multiple Reaction Monitoring Cubed.
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Robin Korte, Jean-marc Monneuse, Elodie Gemrot, Isabelle Metton, Jens BrockmeyerAbstract:Crustacean shellfish allergy ranks among the most frequent and severe food allergies for adults, demanding rugged and sensitive analytical routine methods. The objective of this study was therefore to develop a mass spectrometric approach for the detection of contamination with shrimp and lobster, two economically important types of Crustaceans, in complex food matrices. Following a biomarker approach, we identified proteotypic peptides and developed a multiple reaction monitoring (MRM) method allowing for the identification and differentiation of shrimp and lobster in the food matrix at concentrations down to 0.1%. To further enhance sensitivity, we employed the MRM-cubed (MRM3) mode, which allowed us to detect Crustaceans down to concentrations of 25 μg/g (Crustacean/food, 0.0025%). We hereby present the first mass spectrometric method for the detection of shrimp and lobster in food matrices.
Amir Sagi - One of the best experts on this subject based on the ideXlab platform.
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The Mineralized Exoskeletons of Crustaceans
Extracellular Composite Matrices in Arthropods, 2016Co-Authors: Shmuel Bentov, Shai Abehsera, Amir SagiAbstract:The Crustaceans constitute one of the oldest arthropod taxa, from which insects later evolved (Giribet et al., Nature 413:157–161, 2001; Regier et al., Nature 463:1079–U1098, 2010; Giribet and Edgecombe, Annu Rev Entomol 57:167–186, 2012). A typical feature that characterizes the Crustacea is their mineralized chitinous exoskeleton. The reinforcement of the chitinous exoskeleton with calcium salts and the formation of inorganic-organic composite materials by the Crustaceans represent one of the oldest biomineralization mechanisms to have evolved in animals. The basic function of mineralization is to enhance the mechanical strength of the skeleton. When compared to other animals with mineralized skeletons, Crustaceans face two distinct challenges inherent in the fact that their skeleton is external: first, the animal’s locomotion abilities must not be compromised by its mineralized exoskeleton, and second, the growth mode by periodic molting requires intensive mobilization of minerals during the resorption of the old cuticle and the rapid recalcification of the new cuticle. These two demands are among the prime determinants that govern the various calcification patterns in Crustacea. This review focuses on the mineralogical aspects of the Crustacean exoskeleton with emphasis on the controllable parameters of the mineral phase properties, namely, the degree of mineralization, the degree of crystallization, the phosphate/carbonate ratio, and the involvement of proteins. It also explores potential biomimetic applications inspired by the Crustacean exoskeleton against the background of similarities between Crustaceans and vertebrates, namely, both groups are the only groups in the animal kingdom that combine advanced locomotion with jointed mineralized skeletons. In addition, many Crustaceans have the ability of calcium phosphate mineralization, like vertebrates. These similarities provide unique opportunities to compare different evolutional solutions to similar functional challenges that, in turn, can inspire biomimetic approaches to the development of synthetic bio-composites for various skeleton-related medical applications.
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Gene Silencing in Crustaceans: From Basic Research to Biotechnologies
Genes, 2013Co-Authors: Amir Sagi, Rivka Manor, Tomer VenturaAbstract:Gene silencing through RNA interference (RNAi) is gaining momentum for Crustaceans, both in basic research and for commercial development. RNAi has proven instrumental in a growing number of Crustacean species, revealing the functionality of novel Crustacean genes essential among others to development, growth, metabolism and reproduction. Extensive studies have also been done on silencing of viral transcripts in Crustaceans, contributing to the understanding of the defense mechanisms of Crustaceans and strategies employed by viruses to overcome these. The first practical use of gene silencing in aquaculture industry has been recently achieved, through manipulation of a Crustacean insulin-like androgenic gland hormone. This review summarizes the advancements in the use of RNAi in Crustaceans, and assesses the advantages of this method, as well as the current hurdles that hinder its large-scale practice.
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from the discovery of the Crustacean androgenic gland to the insulin like hormone in six decades
General and Comparative Endocrinology, 2011Co-Authors: Tomer Ventura, Ohad Rosen, Amir SagiAbstract:Over the past six decades, a unique Crustacean endocrine organ, the androgenic gland (AG), has occupied the minds of groups researching Crustacea the world over. Unlike male sexual differentiation and maintenance of sexual characteristics in other arthropods, in Crustaceans these processes are regulated by the unique male AG. Crustaceans present a particular case in which the gametogenic organ (testis) is clearly separated from the organ regulating sex differentiation (the AG), enabling endocrine manipulations. The AG was first discovered in a decapod species and later investigated in detail not only in decapods but also in amphipods and isopods. The key role of the AG in regulating sex differentiation was subsequently validated in a number of representative species of a wide array of Malacostraca. It was in an isopod species that the AG hormone was first discovered. Later, orthologous genes were found in isopods and decapods, with all these genes sharing the key features of the insulin-like superfamily of peptides. This review unfolds the story of the AG and AG-specific insulin-like factors (IAGs) from a historical perspective, highlighting the main achievements in the field and giving a glimpse of future challenges to be addressed.
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Sexual differentiation in decapod Crustaceans: role of the androgenic gland
Invertebrate Reproduction & Development, 1997Co-Authors: Amir Sagi, Eviatar Snir, Isam KhalailaAbstract:Summary In male Crustaceans—unlike vertebrates—the endocrine and gametogenic functions are clearly separated into distinct organs, the androgenic gland and the testis, respectively. The androgenic gland is thought to be the exclusive source of hormone responsible for sex-differentiation and sexual characteristics in Crustaceans. Information on this unique Crustacean organ is revised with respect to its structure, secretion and role in the regulation of the expression of sexual characteristics, and intersexuality. Several decapod models are presented for research on sexual differentation in higher Crustaceans.