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118 results for “freshwater amphipods”
Spatiotemporal dynamics in freshwater amphipod assemblages are associated with surrounding terrestrial land use type - Dataset
<p>Biological assemblages are the result of dynamic processes that have explicit temporal and spatial dimensions. While biodiversity patterns can be directly inferred from the structure of these assemblages, an assessment of changes through time and space is needed to understand how organisms initially assembled and how they are responding to local environmental and biotic factors. Small freshwater streams are particularly affected by contemporary anthropogenic activities and biological invasions, yet are commonly less studied, as studies often focus on lakes and large streams. Here, we conducted a spatially explicit analysis of keystone shredder assemblages across eight years in twelve replicated small tributary streams. In each stream, we monitored multiple sites per km stream length. By assessing temporal beta diversity dynamics, defined by the gain or loss of species or abundance-per-species at individual sites, we show that changes in amphipod assemblages occur within the context of the surrounding terrestrial matrix and reflect recent amphipod colonization history. While amphipod composition was mostly constant in streams located in forested catchments, streams embedded in catchments with more extensive agricultural land use displayed more pronounced temporal changes, either driven by colonization of unoccupied upstream locations, or by more pronounced but undirected fluctuations in gains and losses of species or abundance-per-species. Our study thus suggests that agricultural landscapes might destabilize aquatic amphipod assemblages, causing higher temporal changes in community structures, and highlighting the vulnerability of aquatic ecosystems to terrestrial land use drivers.</p>
Figure 2 in Redescription of the freshwater amphipod Austrochiltonia australis (Sayce) (Crustacea: Amphipoda, Chiltoniidae)
Figure 2. Austrochiltonia australis (Sayce), NMV J46778, large male morphotype, 10.5mm: A, gnathopod 1; B, gnathopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 7; F, pereopod 5; G, pereopod 6; H, telson; I, left and right uropod 3; J, uropod 2; K, uropod 1; L, pleopod 1. Scales: a(A-G), 0.5mm; b(I), 0.1mm; c(H, J-K), 0.1mm; d(L), 0.5mm.
Figure 4 in Redescription of the freshwater amphipod Austrochiltonia australis (Sayce) (Crustacea: Amphipoda, Chiltoniidae)
Figure 4. Austrochiltonia australis (Sayce), NMV J46780, ovigerous female, 8.6mm: A, antenna 1; B, antenna 2; C, inner plate of maxilliped; D, gnathopod 1; E, gnathopod 2; F, left and right uropod 3; G, telson; H, pereopod 4 coxa; I, uropod 2; J, uropod 1; K, oostegite on coxa 2; L, oostegite on coxa 3; M, oostegite on coxa 4; N, oostegite on coxa 5. Scales: a(A-B), 0.5mm; b(F), 0.1mm; c(D-E), 0.5mm; d(I-J), 0.1mm; e(G), 0.1mm; f(K-N), 0.5mm
Figure 1 in Redescription of the freshwater amphipod Austrochiltonia australis (Sayce) (Crustacea: Amphipoda, Chiltoniidae)
Figure 1. Austrochiltonia australis (Sayce), NMV J46778, large male morphotype, 10.5mm: A, Lateral view of body; B, maxilla 1; C, Antenna 1; D, antenna 2; E, maxilliped; F, maxilla 2; G, right mandible; H, left mandible; I, upper lip; J, lower lip. Scales: a(A), 0.5mm; b(C-D), 0.5 mm; c(B,E-H), 0.1mm.
Figure 3 in Redescription of the freshwater amphipod Austrochiltonia australis (Sayce) (Crustacea: Amphipoda, Chiltoniidae)
Figure 3. Austrochiltonia australis (Sayce), NMV J46779, small male morphotype, 4.7mm: A, antenna 1; B, antenna 2; C, lateral view of body; D, uropod 2; E, uropod 1; F, left and right uropod 3; G, pleopod 1. Scales: a(A-B), 0.5mm; b(C), 0.5mm; c(D-E), 0.1mm; d(F), 0.1mm; e(G), 0.5mm.
Figure 7 in Gammarus baysali sp. nov., a new freshwater amphipod species from Turkey (Amphipoda: Gammaridae)
Figure 7. Gammarus baysali sp. nov. Allotype female: A) pereopod 5; B) pereopod 7; C) pereopod 6; D) antenna 1; E) telson; F) uropod 3; G) uropod 2; H) uropod 1; I) pereopod 5; J) uropod 3; K) telson; L) pereopod 7; M) pereopod 6.
Figure 5 in Gammarus baysali sp. nov., a new freshwater amphipod species from Turkey (Amphipoda: Gammaridae)
Figure 5. Gammarus baysali sp. nov. Holotype male: A) pereopod 5; B) pereopod 6; C) pereopod 7; D) pereopod 3; E) pereopod 4; F) epimeral plates.
Figure 4 in Gammarus baysali sp. nov., a new freshwater amphipod species from Turkey (Amphipoda: Gammaridae)
Figure 4. Gammarus baysali sp. nov. Holotype male: A) uropod 2; B) uropod 1; C) antenna 2; D) gnathopod 1 (inner view); D') detail of gnathopod 1 (outer view); E) gnathopod 2 (inner view); E') detail of gnathopod 2 (outer view); F) antenna 1; F') accessory flagellum; G) uropod 3; G') tip of uropod 3.
Figure 2 in Gammarus baysali sp. nov., a new freshwater amphipod species from Turkey (Amphipoda: Gammaridae)
Figure 2. Gammarus baysali sp. nov. Holotype male. Lateral view.
Figure 1 in Gammarus baysali sp. nov., a new freshwater amphipod species from Turkey (Amphipoda: Gammaridae)
Figure 1. Geographical location of Cumayanı Cave.
Origin of the natural variation in the storage of dietary carotenoids in freshwater amphipod crustaceans
<p>Carotenoids are diverse lipophilic natural pigments which are stored in variable amounts by animals. Given the multiple biological functions of carotenoids, such variation may have strong implications in evolutionary biology. Crustaceans such as <i>Gammarus </i>amphipods store large amounts of these pigments and inter-population variation occurs. While differences in parasite selective pressure have been proposed to explain this variation, the contribution of other factors such as genetic differences in the gammarid ability to assimilate and/or store pigments, and the environmental availability of carotenoids cannot be dismissed. This study investigates the relative contributions of the gammarid genotype and of the environmental availability of carotenoids in the natural variability in carotenoid storage. It further explores the link of this natural variability in carotenoid storage with major crustacean immune parameters. We addressed these aspects using the cryptic diversity in the amphipod crustacean <i>Gammarus fossarum</i> and a diet supplementation protocol in the laboratory. Our results suggest that natural variation in <i>G. fossarum</i> storage of dietary carotenoids results from both the availability of the pigments in the environment and the genetically-based ability of the gammarids to assimilate and/or store them, which is associated to levels of stimulation of cellular immune defences. While our results may support the hypothesis that carotenoids storage in this crustacean may evolve in response to parasitic pressure, a better understanding of the specific roles of this large pigment storage in the crustacean physiology is needed.</p>
Ancient volcanos as species pumps: A case study of freshwater amphipods in Northeast Asia
<p>Volcano-tectonic processes have been viewed as primary divers in the formation of present-day diversity. Volcanos associated with mountain uplifts drives allopatric speciation through vicariance and may impact the surrounding areas like species pump or species attractor. However, the application of these hypotheses to aquatic fauna has rarely been tested explicitly. We conducted this research in the Changbai Mountains (Mts), which are one of the most typical, active volcanic ranges in Northeast (NE) Asia with a long and turbulent geological history. The <i>Gammarus nekkensis</i> species complex of amphipod crustaceans, widely distributed throughout NE Asia with poor dispersal abilities and a long evolutionary history, is a suitable model for testing these hypotheses. Phylogenetic and ancestral range reconstructions demonstrated that the studied amphipod originated from the Changbai Mts approximately 27 Ma and diverged into eastern (Clade I) and western (Clade II) clades, which corresponds well with the initial volcanic eruption of the Changbai Mts in the Late Oligocene. The subsequent diversifications of subclades CI-3, CII-1a and CII-2a were likely driven by second and third eruptions of the Changbai Mts during the Miocene. In particular, the Changbai lineages had spread to the Russian Far East multiple times since the Early Miocene, and widely colonized the region during the Pleistocene. Our discoveries suggest that the ancient volcanos of the Changbai Mts act as species pumps in NE Asia, resulted in burst of diversification around the Changbai Mts and subsequent dispersals into adjacent regions.</p>
Ancient volcanos as species pumps: A case study of freshwater amphipods in Northeast Asia
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Origin of the natural variation in the storage of dietary carotenoids in freshwater amphipod crustaceans
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Data from: Ecological effects on metabolic scaling amphipod responses to fish predators in freshwater springs
Metabolic rate is commonly thought to scale with body mass to the 3/4-power as a result of universal body-design constraints. However, recent comparative work has shown that the metabolic scaling slope may vary significantly among species and higher taxa, apparently in response to different lifestyles and ecological conditions, though the precise mechanisms involved are not well understood. To better understand these under-appreciated ecological effects and their causes, it is important to control for extraneous phylogenetic and environmental influences. We demonstrate how this may be done by comparing the ontogenetic scaling of resting metabolic rate among populations of the same species (the amphipod Gammarus minus) in mid-Appalachian freshwater springs with similar, relatively constant environmental conditions, except for the varying presence of the predatory fish Cottus cognatus. We found that populations of G. minus exhibit significantly lower metabolic scaling slopes (0.54 to 0.62) in three freshwater springs with C. cognatus than in two springs without these fish (0.76 to 0.77). We tested multiple hypothetical causes for these population differences. Our results best supported the hypothesis that metabolic scaling was influenced by the effects of size-selective predation on the ontogeny of growth, a metabolically expensive process. The body-size scaling of growth is significantly less steep in the populations inhabiting springs with versus without fish, thus paralleling the interpopulation differences in metabolic scaling. Prematurational growth of G. minus is as high or higher in the fish springs, whereas postmaturational growth is significantly lower, often approaching zero. Similarly the amphipods in the fish springs tend to have higher metabolic rates at small sizes, but lower metabolic rates at large sizes, compared to those in the fishless springs. Our results do not support other hypothetical causes of the interpopulation variation in metabolic scaling, including differential scaling of cell size or low-metabolism body components (fat and mineralized exoskeleton), or possible effects of other environmental factors associated with the presence of fish. However, fish-induced population differences in adult behavioral activity may influence metabolic scaling in G. minus, a possibility under current study. We conclude that ecological factors may significantly influence metabolic scaling, contrary to common belief.
Data from: Parasite-induced inversion of geotaxis in a freshwater amphipod: a role for anaerobic metabolism?
Many parasites with complex life-cycles alter the phenotype of their intermediate hosts in ways that seem to favor transmission to a final host. Although there is a large literature on host manipulation, how parasites alter the phenotype of their hosts remains poorly known. The bird acanthocephalan Polymorphus minutus is known to alter geotaxis in its amphipod host, Gammarus roeseli. Here we examine the potential roles of low oxygen availability and the excretion, by the parasite, of two products from its own anaerobic metabolism (lactate and succinate) in altered geotaxis. Under hypoxia, uninfected Gammarus roeseli showed negative geotaxis and lower metabolic rate, two traits also altered by infection with P. minutus, albeit with different intensities. The injection of a mixture of lactate and succinate in uninfected amphipods mimicked the parasite-induced reversion of geotaxis, without affecting the metabolic rate. In addition, both P. minutus-infected gammarids and uninfected ones conditioned to hypoxia for two days showed elevated levels of lactate in the brain, but not in the hemolymph. Overall, our results indicate that the pathways involved in anaerobic metabolism and hypoxia-signalling might be responsible for the changes in geotaxis and metabolic rate induced by P. minutus infection. Our study emphasizes the need to consider the tight and complex connections between physiological processes and behavioural adjustments, in particular at the brain level, in the understanding of parasitic manipulation, and more broadly of behavioural changes in infected hosts.
FIGURE 5 in Crangonyx islandicus sp. nov., a subterranean freshwater amphipod (Crustacea, Amphipoda, Crangonyctidae) from springs in lava fields in Iceland
FIGURE 5. Crangonyx islandicus sp. nov., female paratype, 6.2 mm, Vatnsvik. A, pereopod 6. B, coxa of pereopod 6. C, pereopod 7. D, spines distally on carpus of pereopod 7. E, pleopod 1. F, pleopod 2. G, pleopod 3. Scale: A–C = 0.5 mm; D = 0.1 mm; E–G = 0.5 mm.
FIGURE 2 in Crangonyx islandicus sp. nov., a subterranean freshwater amphipod (Crustacea, Amphipoda, Crangonyctidae) from springs in lava fields in Iceland
FIGURE 2. Crangonyx islandicus sp. nov., female paratype, 6.2 mm, Vatnsvik. A, antenna 1. B, distal part of flagellum of antenna 1. C, accessory flagellum of antenna 1. D, antenna 2. E, upper lip. F, left mandible, G, lacina mobilis and incisor. H, mandibular palp. I, lower lip. J, maxilla 1. K, maxilla 2. Scale: A, B = 0.5; C–K = 0.1 mm.
FIGURE 7. Sites with C in Crangonyx islandicus sp. nov., a subterranean freshwater amphipod (Crustacea, Amphipoda, Crangonyctidae) from springs in lava fields in Iceland
FIGURE 7. Sites with C. islandicus sp. nov. in Iceland. The large recent glaciers, i.e. Langjökull, Hofsjökull and Vatnajökull, are shown, as well as the large lakes, i.e. Lake Thingvallavatn and Lake Myvatn. Recent lava fields (since last glaciation; <18.000 years, shaded area) are shown as well as the plate boundaries. Source: Institute of Earth Sciences, University of Iceland.
FIGURE 6 in Crangonyx islandicus sp. nov., a subterranean freshwater amphipod (Crustacea, Amphipoda, Crangonyctidae) from springs in lava fields in Iceland
FIGURE 6. Crangonyx islandicus sp. nov., female paratype, 6.2 mm, Vatnsvik. A, uropod 1. B, uropod 2. C, uropod 3. D, uropod 3 and telson. E, telson. Scale: A–D = 0.5 mm; E = 0.1 mm.
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