Hemimysis Anomala Research Articles

Evaluation of eDNA qPCR monitoring as an early detection tool for a non-native mysid in Great Lakes Waters

Early detection of aquatic invasive species (AIS) is vital to cost-effective prevention of their spread in the Great Lakes. Unfortunately, AIS surveillance has been generally too slow and geographically limited to support this purpose. Environmental DNA (eDNA) detection using quantitative polymerase chain reaction (qPCR) offers more rapid and affordable detection of likely AIS presence, but it does not directly discern live/dead status. Vital status verification using conventional surveys following positive eDNA qPCR detections could resolve this barrier, but only if the latter are adequately reliable and sensitive. Here we explore the reliability and sensitivity of eDNA qPCR monitoring for the bloody red shrimp (Hemimysis anomala), an AIS established in the southern Great Lakes but not yet widely distributed in Lake Superior, against conventional microscopy-based methods. We conducted this comparison using 1) harbor water from Muskegon Lake, MI where H. anomala is established, and 2) raw ballast water from ships transporting ballast from lower Lake Michigan to western Lake Superior. Our studies showed positive eDNA qPCR detections of H. anomala in all harbor and ballast samples for which conventional detection results were positive, and in some samples for which conventional results were negative. These results suggest that qPCR assays with adequate specificity could be an important tool in support of more effective and affordable early detection of target species in Great Lakes water, especially when combined with confirmatory conventional monitoring.

Functional responses correspond to stable isotope-based trophic positions among four invasive Ponto-Caspian mysid species (Crustacea, Mysida)

Determining the consumptive effects of non-native predators, for which several direct and indirect methods have been applied, is a common goal in invasion biology. Functional responses and stable isotope analysis are among the most widely used approaches; however, they are rarely used in combination. In this study, we used these two complementary methods to compare the predatory impacts of four invasive Ponto-Caspian mysids on zooplankton in a habitat (Danube River) where all four species coexist. The order of the species based on the attack rates of the functional response models matched with their mean δ15N values, indicating a correspondence between their predatory potentials and trophic positions in their invaded habitat. Hemimysis anomala had the highest attack rate on zooplankton presumably due to its higher degree of specialization linked to its pelagic lifestyle. Contrary to our expectations, the largest species, Paramysis lacustris, had an intermediate predatory efficiency and trophic position, similar to those of Limnomysis benedeni but higher than those of the smallest species, Katamysis warpachowskyi. Nevertheless, all of the four species exhibited a considerable predatory potential, suggesting that any of them can contribute significantly to their combined predatory impact depending on their densities. The congruence between the results of the two methods shows that the species can realize their different predatory potentials in their invaded environment, indicating favorable conditions (i.e., food availability and spatial heterogeneity) which allowed dietary differentiation. We recommend the combined use of functional responses and stable isotope analysis, which might allow robust conclusions to be drawn on the trophic ecology of the species and also provide further insights into the studied ecosystem.

First occurrence of the mysid Hemimysis anomala G.O. Sars, 1907 in Lake Stechlin, Germany

First occurrence of the mysid Hemimysis anomala G.O. Sars, 1907 in Lake Stechlin, Germany

Tracking the real-time behavior of Hemimysis anomala’s winter swarms using acoustic camera

Tracking the behavior of invasive alien species (IAS) is challenging due to logistical constraints that hinder high frequency surveys. Real-time automated recorders offer a promising solution, but their feasibility needs testing and validation. The acoustic camera is an efficient method to obtain real-time records of the behavior of Hemimysis anomala, a mysid that has invaded a variety of aquatic ecosystems. This approach is also a valuable tool for high-quality video recordings of mysid swarms in shallow habitats. The feasibility of this device to record the continuous behavior, including exit and entry (hereafter referred to as emergence and homing) from a shelter over a diel cycle was validated. Emergence consistently correlated with the onset of civil twilight, while homing displayed more intricate temporal trends. Homing events were longer than emergence events, but both were significantly influenced by light conditions. The termination of emergence was concomitant to the onset of the light preference as already shown by past studies. However, homing showed an earlier onset before light conditions exceeded the preference values, possibly due to inter-individual variability and/or information sharing in swarm behavior. The survey also captured the collapse in the targets number detected by the end of March, underlining the termination of the winter swarm. Furthermore, we demonstrated the importance of high-frequency temporal resolution, with a sampling frequency of at least 10-min, to accurately capture the swarm behavior. Overall, we provide original new insights characterizing H. anomala ecology and encourage the development of real-time automated recorders to track the behavior of IAS.

Seasonal variations of the trophic niche width of Hemimysis anomala in Lake Geneva

Seasonal variations of the trophic niche width of Hemimysis anomala in Lake Geneva

Are warm temperatures the key factor to prevent winter swarms of Hemimysis anomala in peri-alpine lakes?

The invasive bloody red mysid, Hemimysis anomala, has recently colonised peri-alpine lakes in Western Europe. During the last decade, scuba divers have regularly reported observations of substantial winter swarms of this animal in Lakes Bourget (France) and Geneva (Switzerland-France). During the last four years, we have regularly dived and observed such phenomena in a variety of habitats, revealing thousands to millions of individuals during the period between December and March, with maximal densities occurring in the water column and small open wrecks in January or February. Surprisingly, however, no swarm was observed during the winters of 2022–2023. This led to the hypothesis that temperature could be the main direct or indirect factor responsible for this lower abundance, resulting in the absence of significant gatherings. Some possible explanations are discussed.

On optimal harvesting policy for two economically beneficial species mysida and herring: a clue for conservation biologist through mathematical model

ABSTRACT In this paper, we have studied the dynamics of two species, ecological model, considering two economically beneficial marine species herring (Clupea harengus) as predator and mysida (Hemimysis anomala) as its prey with Beddington–DeAngelis functional response, the effect of prey refuge and linear harvesting in both populations. The local and global stability of the equilibrium points has been established here. The axial equilibrium point goes through transcritical bifurcation depending on the harvesting effort of both species. The interior equilibrium point goes through super critical Hopf bifurcation depending on prey intrinsic growth rate. Additionally, we have determined the suitable value of the MSY policy for the harvesting and find suitable harvesting level using the optimal control theory, such that both the species persist simultaneously. Finally, numerical simulations have been performed to justify the theoretical findings. It is clear from the numerical simulations that the prey refuge and mutual interference between predators stabilized the unstable system to a stable one. This finding could give some clue to the experimental biologist and business personnel for making management decisions in controlling the harvesting strategies of the two economic beneficial fish populations, mysida and herring.

Elevated methylmercury concentration and trophic position of the non-native bloody red shrimp (Hemimysis anomala) increase biomagnification risk in nearshore food webs

The establishment of non-native species can result in complex shifts in food-web structure and ecosystem function that alter the bioaccumulation, transfer, and biomagnification of contaminants. Hemimysis anomala (the bloody red shrimp), a mysid native to the Ponto-Caspian region that is now established throughout the Laurentian Great Lakes region (North America) and Europe, is characterized by high densities and a trophic ecology that may be consequential to mercury fluxes and bioaccumulation. We combined methylmercury (MeHg) and stable isotope (δ15N and δ13C) analyses of invertebrates from Seneca Lake (NY, USA) to test the hypotheses that mercury concentrations differ among (1) H. anomala and native or naturalized analogs due to food-web position and (2) stages of H. anomala due to ontogenetic diet shifts. The MeHg concentration and δ15N of H. anomala exceeded other littoral invertebrates (such as amphipods, dreissenid mussels, and zooplankton >153 μm) and were as high as the pelagic, native Mysis diluviana. These taxa-specific patterns indicate intensified biomagnification of MeHg is possible in nearshore and reef-spawning fish following the establishment of H. anomala, an energy-dense prey item for economically and ecologically important fish. Larger, adult H. anomala had higher MeHg concentrations and more enriched δ15N than juveniles, and H. anomala collected at a littoral site had higher MeHg than a canal site. These intraspecies contrasts are consistent with the shift toward zooplanktivory in adult H. anomala. As both putative prey for fish and competitors for shared zooplankton resources, H. anomala may impact fish in compounding ways.

A Hemimysis-driven novel ecosystem at a modified rubble-mound breakwater: An Engineering With Nature® Demonstration Project.

The US Army Corps of Engineers (USACE) repairs aging breakwater structures as part of routine maintenance to maintain safe navigation in Great Lakes commercial ports. A USACE repair to an existing breakwater structure in Milwaukee Harbor (WI) implementing Engineering With Nature (EWN) principles created complex rocky habitat by strategically placing cobble-sized stone over conventional 5.4 to 9.1 metric ton boulders, thus creating "control" (boulder) and "treatment" (cobble) habitats. We evaluated the resultant nature-based breakwater (NBBW) developing food web versus an adjacent referencesite on the same breakwater and determined that, unexpectedly, locally abundant Hemimysis anomala were impacting the food-web dynamics and feeding ecology of fishes occupying the structure. Fish and forage communities were sampled using gillnets, night scuba diving surveys, rock collections, and a novel trap to capture invertebrates. The resultant NBBW became home to a prolific population of nonindigenous Hemimysis, with indications that they were more abundant on cobble versus boulders,based on rainbow smelt feeding. This lithophilic/cave swelling mysid provided an important new food resource in Milwaukee Harbor for two introduced pelagic prey fishes: alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax). Gillnetting and night scuba diving surveys confirmed that rainbow smelt preferred to forage on the cobble section (p < 0.05). Hemimysis were also the primary food item consumed by nearshore game fishes such as young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris). We propose that those breakwaters that harbor abundant Hemimysis constitute novel ecosystems (ecosystems that include both native and non-native biota) that might benefit harbor fisheries if well-managed. This project demonstrated how a low-cost design modification could be applied during the repair of rubble-mound, breakwater structures to achieve benefits beyond safe navigation. Integr Environ Assess Manag 2022;18:49-62. Published 2021. This article is a US Government work and is in the public domain in the USA.

Metabarcoding of native and invasive species in stomach contents of Great Lakes fishes.

As aquatic invasive species (AIS) proliferate worldwide, a better understanding of their roles in invaded habitats is needed to inform management and introduction prevention strategies and priorities. Metabarcoding of stomach content DNA (scDNA) shows considerable promise in such regard. We thus metabarcoded scDNA from two non-native fish species (alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax)), and three native ones (bloater (Coregonus hoyi), ninespine stickleback (Pungitius pungitius), and slimy sculpin (Cottus cognatus)). Fishes (N = 376) were sampled in spring 2009 and 2010 from 73–128 m depths at three Lake Michigan sites. Four mitochondrial cytochrome oxidase 1 (CO1) primer sets designed to target five potential AIS prey, and a universal aquatic invertebrate CO1 primer set targeting both native and AIS prey were used. Quality controlled prey amplicons were matched to three AIS prey: Bythotrephes longimanus (mean percent frequency occurrence, all samples = 7%), Cercopagis pengoi (5%), and Dreissena rostriformis bugensis (11%). Neither invasive prey Dreissena polymorpha nor Hemimysis anomala were detected. Native prey Leptodiaptomus sicilis, Limnocalanus macrurus, and Mysis diluviana were relatively common in scDNA (respective mean percent occurrences, all samples: 48%, 25%, 42%). Analysis of variation in prey occurrences for sample site, predator species, sample year, sample depth, and predator total length (TL) indicated site and predator species were most important. However, B. longimanus occurrence in scDNA depended upon predator TL, perhaps indicative of its unique defensive spine limiting susceptibility to predation until fishes exceed species-specific gape-based limitations. Our analysis of native and invasive prey species indicated possible indirect AIS impacts such as native predators switching their diet due to AIS-driven losses of preferred native prey. Metabarcoding demonstrated that AIS are integrated components of the offshore Lake Michigan food web, with both native and non-native predators, and both invasive and native prey are affecting species interactions across multiple trophic levels.

The influence of light, substrate, and fish on the habitat preferences of the invasive bloody red shrimp, Hemimysis anomala

The invasive bloody red shrimp, Hemimysis anomala, is a novel organism in the Laurentian Great Lakes region that utilizes benthic and open-water habitat. Hemimysis is predicted to impact nearshore fish communities in the Northeastern USA where its range is expanding, either negatively through predation of shared zooplankton prey or positively as high-calorie prey. In this experimental study, we examined the factors influencing Hemimysis’ benthic habitat selection, vertical distribution, and susceptibility to fish predation. In the presence of fish cues, Hemimysis preferred cobble over other benthic substrates (Dreissena mussels, pebble, or sand) regardless of light conditions; in dark conditions without a fish present, Hemimysis preferred open waters with sand habitat. Light and fish cues also interacted to influence the vertical distribution of Hemimysis, with the majority of mysids selecting depths that minimized perceived cumulative risk. The mean feeding rates of young-of-year (YOY) alewife (Alosa pseudoharengus), adult round goby (Neogobius melanostomus), YOY yellow perch (Perca flavescens), adult pumpkinseed sunfish (Lepomis gibbosus), and YOY lake trout (Salvelinus namaycush) varied among species, prey densities, and substrate (range = 0.77–57 mysids/fish/h). In general, feeding rates were highest for alewife, a non-native species in the Great Lakes basin, and in refuge-free conditions for all species, except for non-native round goby, which fed at similar rates regardless of prey refuge availability. Collectively, our results suggest that fish feeding success is contingent upon the interaction of light and Hemimysis refuge availability due to behavioral modifications of Hemimysis in the presence of fish and adverse light conditions.

Tests of disinfection methods for invasive snails and zooplankton: effects of treatment methods and contaminated materials

De Stasio BT, Acy CN, Frankel KE, Fritz GM, Lawhun SD. Tests of disinfection methods for invasive snails and zooplankton: effects of treatment methods and contaminated material. Lake Reserv Manage. 35:156–166.The spread of aquatic invasive species (AIS) in lakes and reservoirs is a major issue that will grow in importance due to possible economic, environmental, and human health impacts of AIS as the number of potentially harmful invasive species continues to increase. There is a pressing need for scientific information on which procedures can effectively decontaminate and disinfect sampling gear against multiple AIS. We determined effectiveness of cleaning methods on 4 recent AIS in WI: New Zealand mud snail (NZMS; Potamopyrgus antipodarum), faucet snail (Bithynia tentaculata), spiny water flea (Bythotrephes longimanus), and bloody-red mysid shrimp (Hemimysis anomala). We tested mortality in the laboratory following total immersion and spraying procedures, as well as the effects of 5 types of materials likely to be contaminated. Freezing was effective, but not practical for large sampling equipment and boats. Desiccation did not result in 100% mortality for NZMS or faucet snail. Bleach (500 ppm) was effective on spiny water flea and bloody-red mysid, but not on either snail. Immersion in Virkon (2%) was effective on all species within 20 min. Spraying was less effective than total immersion, especially on some materials. Our results provide rigorous data for establishing practical guidelines on disinfection methods for managers, researchers, and citizen scientists battling the spread of AIS in lakes and reservoirs.

Temporally variable niche overlap and competitive potential of an introduced and a native mysid shrimp

Temporal patterns of interspecific interactions and their correspondence with life history events are of key significance for community dynamics, but often overlooked in characterising the mechanisms of species invasions and predicting competitive outcomes. Here, we examine the role of seasonality in moderating interactions between a globally important invasive mysid shrimp (Hemimysis anomala) and an ecologically similar native species (Mysis salemaai) by combining distribution and diet surveys with experimental quantification of comparative resource exploitation rates and mutual aggressive interactions. We found partial overlap in winter, but not summer horizontal distributions of the two species. Diets were highly similar in the seasonally overlapping range, potentially resulting in competition for the high-quality, but seasonally scarce, zooplankton prey in invaded lakes. Despite its smaller size, H. anomala had similar feeding rates to M. salemaai on three key zooplankton prey species. H. anomala was more aggressive toward M. salemaai than M. salemaai was toward H. anomala, although there was no evidence for intraguild predation. Our findings indicate that spatio-temporal niche partitioning permitted invasion by H. anomala and coexistence with M. salemaai, in spite of their high trophic similarity.

Stomach contents and stable isotopes analysis indicate Hemimysis anomala in Lake Ontario are broadly omnivorous

Abstract Hemimysis anomala is a recent invader to North American aquatic ecosystems and is spreading rapidly throughout the Great Lakes region. This is the first littoral mysid in the North American Great Lakes; and, as such, the ecosystem effects are unknown and could be substantial. These effects depend on the role of Hemimysis in the food web and, therefore, on its diet. We examined the stomach contents of two life stages of Hemimysis from two sites in Lake Ontario during the growing season (May–November 2010). We also report the relationship between zooplankton hard parts and size for a number of potential prey species to allow the back-calculation of prey lengths from stomach contents. Both juvenile (2–5 mm) and adult Hemimysis (5–11 mm) were omnivorous, consuming phytoplankton, zooplankton, and benthos when available. However, adults appeared slightly more carnivorous and incorporated larger prey in their diets. Hemimysis were able to consume zooplankton prey up to 30% of their own length, including Bythotrephes longimanus and Cercopagis pengoi. Daphnia and Bosmina were selected over other prey by both juvenile and adult Hemimysis and were most common in stomachs during July and September when their abundances in the zooplankton were highest. Measurements of δ13C and δ15N corroborated stomach content materials, indicating an omnivorous diet which included benthic and pelagic sources. Omnivory by Hemimysis is typical of mysids in general and makes them less sensitive to seasonal dynamics of preferred prey items.

What is the invasiveness of Hemimysis anomala (Crustacea, Mysidae) in the large deep Lake Bourget, France?

Non-native species are a major threat to aquatic ecosystems and the assessment of their invasiveness may be limited by the diverse ecological features needed to be accounted for. In this study, we combined complementary features of the autoecology and trophic ecology of Hemimysis anomala in a large deep lake (Lake Bourget) to assess its invasiveness. It was present in more than 80% of the 23 sites explored, indicating an extensive colonization of the lake. The mysid exhibited at least two generations per year, and the median individual growth rate was ~ 0.04 mg dry mass day−1 and ~ 0.09 mg dry mass day−1 for juveniles and adults, respectively. Consequently, the daily production for a typical reproductive swarm could reach more than 250 mg dry mass day−1 m−2 representing an important hotspot of secondary production. Individual measurements of stable carbon (δ13C) and nitrogen (δ15N) isotopes highlighted a trophic ontogenetic shift and indicated that subpopulations of H. anomala could mainly rely either on benthic or pelagic resources depending on the slope of the site. Because of its extensive colonization, its high growth rate, and trophic plasticity, H. anomala exhibits a high invasiveness and may strongly alter the food web of Lake Bourget.

Tissue-specific turnover and diet-tissue discrimination factors of carbon and nitrogen isotopes of a common forage fish held at two temperatures.

The application of stable isotopes to foraging ecology is dependent on understanding life-history and environmental factors unrelated to diet that may influence isotopic composition. Diet-tissue discrimination factors (DTDFs) and turnover rates will increase the accuracy of isotope-based studies. Furthermore, little consideration has been given to the effects of temperature or life-history stage on isotopic ratios despite the prevalence of variation in temperature and growth rates throughout life. We measured δ13 C and δ15 N values with an elemental analyzer coupled to a continuous flow isotope ratio mass spectrometer. These values were used to estimate turnover and DTDFs for Emerald Shiners (Notropis atherinoides), a common North American freshwater forage fish. Fish were assigned to a temperature treatment, either 10°C (Low) or 20°C (High), and provided one of three diets (commercial pellet, Artemia salina, or Hemimysis anomala). At regular intervals fish were sampled and the isotopic compositions of whole body and liver tissues were determined. Tissue turnover rates for fish fed Artemia were faster for liver than for whole body, but were also influenced by temperature. Turnover occurred faster at higher temperatures for body and liver δ15 N values, but not for δ13 C values. The pellet and Hemimysis treatments were in isotopic equilibrium from the start of the experiment and estimated DTDFs based on these treatments were lower than assumed for Δ15 N (+0.6 to 2.7‰) and variable, but within expected ranges for Δ13 C (-1.9 to +1.5‰). The results for Emerald Shiners differed from commonly made assumptions for applying stable isotopes to ecological questions, possibly related to a bias in the use of juveniles in studies of turnover and DTDFs and assumptions regarding thermal-independence of isotopic relationships. The species-specific DTDF and tissue turnover estimates provided here will inform interpretations of stable isotope data for smaller fish species and improve food-web studies.

The light at the end of the funnel?: Using light-based traps for the detection and collection of a nearshore aquatic, invasive invertebrate, Hemimysis anomala

Abstract Early detection of aquatic, non-native species can be challenging due to low densities, multiple life stages, and unpredictable conditions. This has led to calls for novel approaches to improve detection as well as facilitate control and eradication of emerging invaders. We explored if subaquatic traps that utilize the behavioral response of organisms to preferred light conditions could effectively capture Hemimysis anomala , an invertebrate that is expanding its range in aquatic systems throughout Europe and North America. Light-based traps provided a reliable alternative to monitoring with plankton nets and traps, as this invertebrate seeks refuge in crevices that are inaccessible to most sampling gear. In the field (Seneca Lake, NY USA), light-based traps of two designs—bucket and funnel traps—were highly effective at capturing Hemimysis , with limited non-target catch. Trap collections were representative of the juvenile-dominated population surveyed by concurrent net tows. In the laboratory, funnel traps were more successful than bucket traps at capturing Hemimysis . Funnel traps attracted 25 to > 80% of organisms introduced into aquaria. Once introduced into the trap, approximately 80% of organisms were retained, with no systematic difference in the demographic characteristics between organisms that remained and those that escaped. Light-based traps are a promising monitoring strategy across a range of densities (7 to nearly 1000 Hemimysis /m 3 based on our laboratory and field studies) for this rapidly expanding Ponto-Caspian invader that has the potential to impact recipient communities. As the behavior and life cycle of many aquatic species are tied to light intensity, the traps we describe for Hemimysis may be applied to the early detection of other species for which light preferences are known.

New cyclopoid copepod (Thermocyclops crassus) reported in the Laurentian Great Lakes

Abstract The cyclopoid copepod Thermocyclops crassus, native to Eurasia and Africa, was detected at two sites in the western basin of Lake Erie in August 2014. T. crassus was subsequently detected in samples collected from two sites in western Lake Erie in August 2015 and four sites in August 2016. Densities of adult T. crassus remained relatively low but increased each year, averaging 1.3 individuals/m 3 in 2014, 12.8 individuals/m 3 in 2015, and 35.5 individuals/m 3 in 2016. The only other documented occurrence of T. crassus in either the United States or Canada has been in Lake Champlain's Missisquoi Bay in 1991. This is the first finding of an exotic species introduced into the Laurentian Great Lakes since the discovery of Hemimysis anomala in Lake Michigan in 2006.

Success factors and future prospects of Ponto–Caspian peracarid (Crustacea: Malacostraca) invasions: Is ‘the worst over’?

Ponto–Caspian peracarids (amphipods, isopods, mysids and cumaceans) represent one of the most successful groups of aquatic invaders comprising several high-impact species, such as Chelicorophium curvispinum, Dikerogammarus villosus, or Hemimysis anomala. In the present study we made the first attempt to compare biological traits and the environmental preferences of invasive and non-invasive members of the group based on both literature and field data (Joint Danube Survey 3, 2013) with the goal of identifying factors linked to invasion success and drawing conclusions on future invasion risks. Both datasets indicated substrate preference as an important factor in spontaneous range expansion; all invasive species are lithophilous, whereas the majority of non-invasives are psammo-pelophilous. The remaining seven presently non-invasive lithophilous species deserve special attention when considering potential future invaders; however, due to their rarity and possible negative interactions with earlier colonists we consider the probability of their expansion in the foreseeable future as low. Their potential expansion could most likely be of minor consequence anyway, since no considerable functional novelty can be attributed to them in addition to species already present. In this limited context (regarding habitats dominated by hard substrates and not considering the potential further spread of already invasive species) it might be justified to conclude that ‘the worst is over’. Nevertheless, impending navigation development projects both in the Danube–Main–Rhine and Dnieper–Pripyat–Bug–Vistula systems might favour the future spread of non-lithophilous species, which might imply a new invasion wave of Ponto–Caspian peracarids.

The Mysidae (Crustacea: Peracarida: Mysida) in fresh and oligohalinewaters of the Mediterranean. Taxonomy, biogeography, and bioinvasion.

A census of Mysidae yielded a total of twelve species plus two non-nominotypical subspecies found so far in fresh and oligohaline waters of the Mediterranean, all belonging to the subfamily Mysinae. Among the nine species in fresh-waters, three are stenoendemics, namely of a single lake (Diamysis lacustris), of two neighbouring river systems (Paramysis kosswigi) or of karstic cave waters (Troglomysis vjetrenicensis). Four species-T. vjetrenicensis, D. lacustris, D. fluviatilis, and Paramysis adriatica sp. nov. described in this paper-are confined to freshwater tributaries of the Adriatic Sea (NE-Mediterranean). This strengthens previous findings about the outstanding role of the Adriatic basin for the endemic diversity of freshwater Mysidae within the Mediterranean. This is possibly related to alternating marine and freshwater-terrestrial phases during the Pliocene-Pleistocene in this semi-enclosed basin. Based on current knowledge, freshwater populations of D. mesohalobia heterandra are also confined to the Adriatic basin; this taxon, however, shows many more populations in brackish waters of the E-Mediterranean and Marmora basins. Two freshwater species (Limnomysis benedeni, Hemimysis anomala) are wide-range invaders of Ponto-Caspian origin, with recent expansion into fresh and brackish waters of the NW-Mediterranean. A further immigrant to this part of the Mediterranean, Neomysis integer, is of NE-Atlantic origin and occurs only marginally in fresh-water. Five among the nine species found at least once in fresh-water were also reported in oligohaline conditions, mostly also at even higher salinities. A total of eight species plus two subspecies were recorded in oligohaline waters (S = 0.5-5). Among these, only one oligohalobious stenoendemic, Diamysis hebraica, inhabits streams at the Levantine coast. In the historical biogeographical context, the current distribution of only one out of nine indigenous species in an- to oligohaline waters of the Mediterranean, namely the mainly meso- to polyhalobious Mesopodopsis slabberi, may date back to the early Pliocene flooding of the Mediterranean by Atlantic waters and to later events. For most species, the biogeographical pattern points to a primary origin in the brackish (Miocene) Paratethys; solely the cave-dwelling T. vjetrenicensis has more ancient roots in the Tethyan (Mesogeic) Sea. Both these hypotheses are supported by chorological data and mainly the mineral composition of statoliths. The statoliths are composed of CaCO₃ as the metastable crystal phase vaterite in nine species plus two subspecies considered versus the otherwise more common CaF₂ (fluorite) in only three species (or in 7 + 2 versus two Mediterranean indigenes). All 12 + 2 Mediterranean taxa are figured and described in detail, particularly regarding P. adriatica sp. nov. and the substantially redescribed T. vjetrenicensis Stammer, 1933. Supplementary descriptions are given for P. kosswigi Băcescu, 1948, D. hebraica Almeida Prado-Por, 1981, and N. integer (Leach, 1814). A key to the 14 taxa is given including additional three species of potential future invaders. The tribe Mysini Haworth, 1825, is revised by detachment of the newly defined tribe Paramysini and of the revalidated Hemimysini Czerniavsky, 1882. A key to the resulting six tribes of the subfamily Mysinae is given.