Amphipod Species Research Articles

Microsporidian Parasites Found in the Hemolymph of Four Baikalian Endemic Amphipods.

At present, approximately 187 genera and over 1300 species of Microsporidia have been described, among which almost half infect aquatic species and approximately 50 genera potentially infect aquatic arthropods. Lake Baikal is the deepest and one of the oldest lakes in the world, and it has a rich endemic fauna with a predominance of arthropods. Among the arthropods living in this lake, amphipods (Crustacea) are the most dominant group and are represented by more than 350 endemic species. Baikalian amphipods inhabit almost all depths and all types of substrates. The age and geographical isolation of this group creates excellent opportunities for studying the diversity, evolution and genetics of host-parasite relationships. However, despite more than 150 years of study, data investigating the microsporidia of Lake Baikal remain incomplete. In this study, we used molecular genetic analyses to detect microsporidia in the hemolymph of several endemic species of amphipods from Lake Baikal. We provide the first evidence that microsporidian species belonging to three genera (Microsporidium, Dictyocoela and Nosema) are present in the hemolymph of Baikalian endemic amphipods. In the hemolymph of Eulimnogammarus verrucosus, we detected SSU rDNA of microsporidia belonging to the genus Nozema. In the hemolymph of Pallasea cancellous, we found the DNA of Microsporidium sp. similar to that in other Baikalian endemic amphipods; Dictyocoela sp. was found in the hemolymph of Eulimnogammarus marituji and Acanthogammarus lappaceus longispinus.

Temporal variation of the gammaridean fauna (Crustacea, Amphipoda) associated with the sponge Mycale angulosa (Porifera, Demospongiae) in southeastern Brazil

Marine sponges are advantageous microhabitats because of their complex architecture. The system of internal canals provides circulation of water and deposition of particulate organic matter, ensuring availability of food and shelter. Diminutive amphipods have little difficulty penetrating the spaces of sponges and remain in their aquiferous systems as one of the most abundant taxa in this association. This study evaluated the temporal variation of the gammaridean amphipod species associated with the sponge Mycale angulosa. Sponge samples were collected every three months over one year at Pontal da Cruz Beach, Sao Sebastiao Channel, southeastern Brazil. The amphipod assembly varied over time, while the amphipod density and sponge biomass remained approximately constant. Six species contributed to the temporal variation infaunal composition, highlighting the importance of the natural history of each species.

Host-shift speciation in Antarctic symbiotic invertebrates: further evidence from the new amphipod species Lepidepecreella debroyeri from the Ross Sea?

Lepidepecreella debroyeri n. sp. (Amphipoda, Lysianassoidea) is described from specimens collected at Terra Nova Bay (Ross Sea, Antarctica) in the framework of several scientific expeditions of the Italian National Antarctic Research Program. This amphipod is an obligate parasite of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) and also occurs at diving depths. L. debroyeri n. sp. shares with Lepidepecreella andeep Berge, Vader & Lockhart, 2004, an abyssal species described for the Weddell Sea, an almost identical morphology and ecological traits, being both associated with sea urchins of two different families. This close relationship could be the result of a host-shift phenomenon that occurred during the high number of glacial cycles, possibly rendering the preferred host unavailable. L. debroyeri n. sp. shows a high degree of variation in terms of sex ratio and population structure between different host specimens, a fact that could be related to a great mobility of this small parasitic amphipod. The new amphipod species is itself the subject of a hyperparasitic interaction, carrying tantulocarid crustaceans on the pleopods. This represents the first record of a symbiotic interaction between a tantulocarid and an amphipod for the Southern Ocean.

A new amphipod species (Peracarida: Amphipoda: Ampithoidae) collected from Cenote Aerolito, Cozumel Island, Quintana Roo

A new species of amphipod belonging to the family Ampithoidae was collected from Cenote Aerolito, Cozumel Island, Quintana Roo associated with a macroalgae bed. The main differences between the new species and the previously recorded species in the Gulf of Mexico and Caribbean Sea, Cymadusa compta and Cymadusa setosa respectively, are also presented. The new species increases the globally described number of Cymadusa species to 33.

Ampithoidae and Maeridae amphipods from Timor-Leste (Crustacea: Peracarida)

Five known and four new species of amphipod are documented from Timor-Leste. The species biodiversity of the region shows a close affinity to what is known from tropical north Australia. Although records of amphipods from the Lesser Sunda Region are limited, the species recorded have distributions throughout the broader Indo-Pacific. The new species Ampithoe atauro, Elasmopus tibarensis, Linguimaera christorei and Quadrimaera metinaro are described herein.

An integrated study on Gammarus elvirae (Crustacea, Amphipoda): perspectives for toxicology of arsenic-contaminated freshwater.

The Italian region Latium is characterized by extensive quaternary volcanic systems that contribute greatly to arsenic (As) contamination of freshwater, including drinking water supplies. However, knowledge of the possible toxic effects in these aquatic environments is, despite being highly relevant to public health, still limited. In this paper, we approach this issue using Gammarus elvirae, an amphipod species that inhabits rivers and streams in central Italy, including Latium. We explored the possibility of using G. elvirae in the toxicology of freshwater by addressing the most relevant issues. First, we tested the usefulness of hemocytes from G. elvirae in determining non-specific DNA damage by means of the Comet assay after exposure (24 h and 7 days) to different river water samples in Latium; second, we provided an interpretative overview of the usefulness of hepatopancreatic epithelial cells of G. elvirae as a means of assessing toxicity after long-term exposure to As and other pollutants; third, the LC (50-240 h) value for G. elvirae was estimated for arsenate, which is usually the dominant arsenic species in surface waters. Our study sheds light on G. elvirae at different levels, providing a background for future toxicological research of freshwater.

Corophiine amphipods of the genera Chelicorophium and Paracorophium from the lower Gulf of Thailand (Crustacea, Amphipoda, Corophiidae, Corophiinae).

Two species of corophiine amphipods from Songkhla Lake, in the lower Gulf of Thailand, are described and illustrated. Chelicorophium madrasensis (Nayar, 1950), found in the mangrove forest, has not previously been observed in Thai waters. Paracorophium angsupanichae sp. n. is characterized by its chelate male gnathopod 2, obtuse palm with subrectangular distomedial elevation, and urosomites 1-3 free. This is the first record of the genus Chelicorophium and Paracorophium in Thai waters. All specimens are deposited in the Princess Maha Chakri Sirindhorn Natural History Museum, Prince of Songkla University, Thailand and the Museum für Naturkunde, Berlin.

Attachment ability of two invasive amphipod species may promote their spread by overland transport

Abstract Amphipods are very successful invaders in European inland waters including lakes. There are several vectors identified as responsible for amphipod species introductions and spread, with overland transport increasingly recognized as particularly important, especially in conjunction with transport between sites of sailing and/or angling activity. In this study two species of invasive gammarids with a wide distribution range in Europe, Dikerogammarus haemobaphes and Pontogammarus robustoides, were tested for their ability to attach and remain adhered to sailing rope. The results of the experiment show that both species may have high potential to be transported with sailing/angling equipment, as the percentage of individuals remaining attached to the rope after 30 s of ‘holding’ followed by 30 s of ‘shaking’ was very high (24% and 17%, for D. haemobaphes and P. robustoides, respectively). The necessity for preventative measures to stop translocation of these species between European water bodies is emphasized and discussed. Copyright © 2015 John Wiley & Sons, Ltd.

Abundance and diversity of amphipods (Crustacea: Peracarida) on shallow algae and seagrass in lagoonal ecosystem of the Mediterranean Tunisian coast

Bizerte lagoon is a semi-enclosed marine ecosystem, where various types of human activities have been developed. To investigate the distribution and temporal variation of amphipod assemblage, monthly sampling was conducted at the Menzel Jemil site from October 2009 to September 2010. Atotal number of 3,620 specimens were collected from floating algae and seagrass allowing the identification of 10 amphipod species. Moreover, several indices, species richness, dominance, mean density, and diversity index were estimated to characterize the amphipode assemblage. Gammarusaequicauda wasthe most dominant species in all seasons. In addition, the minimum and maximum values of species richness of amphipod were observed in January (3 species) and April (8 species), respectively. The mean density and species richness were negatively correlated with plant biomass. Mean Shannon index (H')and evenness (J')were 1.62 ± 0.34 and 0.67 ± 0.16, respectively. Non-metric multidimensional scaling (MDS) analysis based on the mean species density showed three seasonal groups of samples. Therefore, canonical correspondence analysis (CCA) made it possible to summarize the overall situation for the species, monthly sampling, and environmental parameters on a single graph. Thus, the temperature, turbidity, and chlorophyll a content are the most often reported factors for the distribution and structure of amphipods in the Bizerte lagoon.

Morphological evolution of coexisting amphipod species pairs from sulfidic caves suggests competitive interactions and character displacement, but no environmental filtering and convergence.

Phenotypically similar species coexisting in extreme environments like sulfidic water are subject to two opposing eco-evolutionary processes: those favoring similarity of environment-specific traits, and those promoting differences of traits related to resource use. The former group of processes includes ecological filtering and convergent or parallel evolution, the latter competitive exclusion, character displacement and divergent evolution. We used a unique eco-evolutionary study system composed of two independent pairs of coexisting amphipod species (genus Niphargus) from the sulfidic caves Movile in Romania and Frasassi in Italy to study the relative contribution and interaction of both processes. We looked at the shape of the multifunctional ventral channel as a trait ostensibly related to oxygenation and sulfide detoxification, and at body size as a resource-related trait. Phylogenetic analysis suggests that the sulfidic caves were colonized separately by ancestors of each species. Species within pairs were more dissimilar in their morphology than expected according to a null model based on regional species pool. This might indicate competitive interactions shaping the morphology of these amphipod species. Moreover, our results suggest that the shape of the ventral channel is not subject to long-term convergent selection or to the process of environmental filtering, and as such probably does not play a role in sulfide tolerance. Nevertheless, the ancestral conditions reconstructed using the comparative method tended to be more similar than null-model expectations. This shift in patterns may reflect a temporal hierarchy of eco-evolutionary processes, in which initial environmental filtering became later on superseded by character displacement or other competition-driven divergent evolutionary processes.

An assessment of Putative Sexually Antagonistic Traits in a Freshwater Amphipod Species

AbstractSexual conflict can result in an ‘evolutionary arms race’ between males and females, with the evolution of sexual antagonistic traits used to resolve the conflict in favor of one sex over the other. We assessed the resolution of sexual conflict in a Hyalella amphipod species by manipulating putative sexually antagonistic traits in males and females and used mate‐guarding duration as our metric of conflict resolution. We discovered that large male posterior gnathopod size increased mate‐guarding duration, which suggests that it is a sexually antagonistic trait in this species. In contrast, female and male body size did not significantly affect mate‐guarding duration. Given that male posterior gnathopods show heightened condition dependence, future investigations should explore the interactive effects of sexual conflict and ecological context on trait evolution, phenotypic divergence, and speciation to elucidate the complex mechanisms involved in the evolution of biological diversity.

Melita mirzajanii n. sp. (Crustacea: Amphipoda: Melitidae), a puzzling new member of the Caspian fauna.

Described is Melita mirzajanii n. sp. (Melitidae) from the southwestern corner of the Caspian Sea. It shows no particular similarity to any species known from the Mediterranean Sea. It inhabits, as the only amphipod species, dense growths of Amphibalanus cf. improvisus (Darwin 1854) in a port, at low and highly fluctuating salinities. Its most striking characters are: absence of any pleonal or urosomal dorsal teeth (projections), elongated distal article of the mandibular palp, hind margin of last pereopod bases strongly narrowed distad, and epimera posterodistally rectangular. An identification key for the species group of Melita without dorsal teeth and without article 2 on the exopodite of the third uropod is provided.

Preference and avoidance reactions in some Baikalian amphipods and holarctic Gammarus lacustris Sars, 1863 in response to a humic-containing preparation

The reactions of preference and avoidance in response to humic-containing preparation (HCP) have been studied in four species of Baikalian amphipods and in Holarctic Gammarus lacustris Sars, 1863. The differences in the behavioral reactions of amphipods have been revealed. The order of amphipods in terms of the extent of HCP preference is as follows: G. lacustris > Gmelinoides fasciatus Stebbing, 1899 ≥ Eulimnogammarus flavus (Dybowski, 1874). The deepwater Ommatogammarus flavus (Dybowski, 1874) exhibited neither preference nor avoidance reactions in response to HCP. Potential relations between revealed reactions of amphipods, conditions, and depths of their habitats and spread off Lake Baikal are discussed.

Description of Pseudingolfiella possessionis n. sp. (Crustacea, Amphipoda) from sub-Antarctic Île de La Possession, Crozet archipelago: the second freshwater amphipod known from the Antarctic biome, a human introduction of Gondwanan ancestry?

A new species of freshwater amphipod, Pseudingolfiella possessionis n. sp. (Senticaudata, Pseudingolfiellidae), is described from the submerged moss vegetation of small brooklets at sub-Antarctic Île de La Possession, Crozet archipelago. It constitutes the second freshwater amphipod species known for the sub-Antarctic and Antarctic region, and the fourth member of the genus. The main characters distinguishing it from all congeners are: the spine on the posterior margin of the dactylus, incisor and lamina mobilis of mandible each with 5 teeth, the setation of the maxilliped, the vestigial second article of pleopod 3 in the female, the undulate and laterally notched posterolateral margin of the external ramus of uropods 1 and 2 in the male, the spinulate dorsomedian projection of the telson.

Effects of light pollution on the emergent fauna of shallow marine ecosystems: Amphipods as a case study

Light pollution from coastal urban development is a widespread and increasing threat to biodiversity. Many amphipod species migrate between the benthos and the pelagic environment and light seems is a main ecological factor which regulates migration. We explore the effect of artificial lighting on amphipod assemblages using two kind of lights, LED and halogen, and control traps in shallow waters of the Great Barrier Reef. Both types of artificial light traps showed a significantly higher abundance of individuals for all species in comparison to control traps. LED lights showed a stronger effect over the amphipod assemblages, with these traps collecting a higher number of individuals and differing species composition, with some species showing a specific attraction to LED light. As emergent amphipods are a key ecological group in the shallow water environment, the impact of artificial light can affect the broader functioning of the ecosystem.

Indirect effects of predators control herbivore richness and abundance in a benthic eelgrass (Zostera marina) mesograzer community.

Herbivore communities can be sensitive to changes in predator pressure (top-down effects) and resource availability (bottom-up effects) in a wide range of systems. However, it remains unclear whether such top-down and bottom-up effects reflect direct impacts of predators and/or resources on herbivores, or are indirect, reflecting altered interactions among herbivore species. We quantified direct and indirect effects of bottom-up and top-down processes on an eelgrass (Zostera marina) herbivore assemblage. In a field experiment, we factorially manipulated water column nutrients (with Osmocote(™) slow-release fertilizer) and predation pressure (with predator exclusion cages) and measured the effects on herbivore abundance, richness and beta diversity. We examined likely mechanisms of community responses by statistically exploring the response of individual herbivore species to trophic manipulations. Predators increased herbivore richness and total abundance, in both cases through indirect shifts in community composition. Increases in richness occurred through predator suppression of common gammarid amphipod species (Monocorophium acherusicum and Photis brevipes), permitting the inclusion of rarer gammarid species (Aoroides columbiae and Pontogeneia rostrata). Increased total herbivore abundance reflected increased abundance of a caprellid amphipod species (Caprella sp.), concurrent with declines in the abundance of other common species. Furthermore, predators decreased beta diversity by decreasing variability in Caprella sp. abundance among habitat patches. Osmocote(™) fertilization increased nutrient concentrations locally, but nutrients dissipated to background levels within 3m of the fertilizer. Nutrient addition weakly affected the herbivore assemblage, not affecting richness and increasing total abundance by increasing one herbivore species (Caprella sp.). Nutrient addition did not affect beta diversity. We demonstrated that assemblage-level effects of trophic manipulations on community structure are the result of distinct and often indirect responses of herbivore species. These results underscore the importance of understanding herbivore-herbivore interactions in a system commonly subjected to both eutrophication and overfishing.

Distribution, diversity and some ecological characteristics of benthic amphipods in the Kapidağ Peninsula (Marmara Sea, Turkey)

Abstract The aim of this study was to determine the environmental factors affecting the fauna and the distribution of benthic amphipod species occurring on the Kapıdağ Peninsula, which is located in the south of the Marmara Sea. A total of 31 amphipod species were identified during the course of this study. In both seasons, Jassa marmorata (Holmes, 1905) and Protohyale schmidtii (Heller, 1866) were the most abundant species. During the study, temperature varied between 11.0 and 17.8°C, while salinity varied between 12.5 and 18.7 PSU; values of dissolved oxygen and pH ranged from 7.2 to 11.4 mg l-1 and 7.2 to 8.5 respectively at the coastal sites where hard bottom sampling was conducted. However, with regard to other sites where soft bottom sampling was carried out, the temperature varied between 8.0 and 18.0°C, salinity between 17.7 and 29.2 PSU, while values for dissolved oxygen and pH ranged from 5.1 to 11.4 mg l-1 and 7.8 to 8.7, respectively. In addition, the study of the amphipod species distribution revealed that the number of species was higher in spring compared to autumn while the number of individuals was higher in autumn compared to spring.

10-Day survival of Hyalella azteca as a function of water quality parameters

Estuarine systems are among the most impacted ecosystems due to anthropogenic contaminants; however, they present unique challenges to toxicity testing with regard to varying water quality parameters. The euryhaline amphipod species, Hyalella azteca, is widely used in toxicity testing and well suited for testing estuarine water samples. Nevertheless, the influence of relevant water quality parameters on test endpoints must be quantified in order to efficiently use this species for routine monitoring. Here, we studied the influence of five water quality parameters: electrical conductivity, pH, un-ionized ammonia, dissolved oxygen and temperature, on H. azteca survival in a water column toxicity test. A model was developed to quantify and predict the independent and interacting effects of water quality variables on 10-day survival. The model allows simultaneous assessment of multiple potential predictors recorded during the tests. Data used for modeling came from 1089 tests performed on ambient water samples over a period of three years (2006–2008). The final model reflects significant effects of predictors and their two-way interactions. The effect of each level of all predictors on survival probability of H. azteca was examined by comparing levels of each predictor at a time, while holding all others at their lowest (reference) level. This study showed that predictors of survival in water column tests should not be evaluated in isolation in the interpretation of H. azteca water column tests. Our model provides a useful tool to predict expected control survival based on relevant water quality parameters, and thus enables the use of H. azteca tests for toxicity monitoring in estuaries with a wide range of water quality conditions.

Debroyerella gen. nov. and Ulladulla gen. nov., two new lysianassoid genera (Crustacea, Amphipoda, Lysianassoidea)

Two new genera and a new species of lysianassoid amphipods are described. Debroyerella gen. nov. is described for three Antarctic species previously assigned to the genus Cheirimedon. Ulladulla gen. nov. is described to accommodate the new species U. selje, from Australian waters. Diagnostic descriptions are given for the genera and all species are described in full.

An empirical test of stable species coexistence in an amphipod species complex.

The ability of phenotypically similar species to coexist at local scales is paradoxical given that species that closely resemble each other should compete strongly for resources and thus be subject to competitive exclusion. Although theory has identified the key requirements for species to stably coexist, empirical tests of coexistence have rarely been conducted. We explored a key requirement for species to stably coexist: a species can invade a community when it is initially rare. We also assessed whether primary productivity (manipulated using phosphorus availability) affected invasion success by increasing the amount of resources available. Using two mesocosm experiments and an assemblage of phenotypically similar amphipod species in the genus Hyalella, we found no evidence for invasion success among the three Hyalella species. Further, patterns of species exclusions differed among the species, which suggests that one species is an especially poor competitor. Finally, these patterns were consistent regardless of whether mesocosms were fertilized with low or high levels of phosphorus. Our results, suggest that species differences in resource competition and predator avoidance ability found in previous studies using these Hyalella species may not be sufficient to allow for coexistence. Moreover, our study demonstrates the importance of using a variety of empirical approaches to test species coexistence theory.