Menidia Menidia Research Articles

Genetic and maternal variation in early growth in the Atlantic silverside Menidia menidia

In the early life histories of many fish species, larger individuals have lower mortality rates and, as a consequence, growth is thought to be a primary determinant of recruitment. Although much is known about environmental influences on growth in the early life history, far less is known about genetic and maternal contributions. As the relative contributions of maternal, genetic, and environmental effects determine how populations respond to selective harvest, evaluating their magnitudes is an important step in constructing evolutionarily sustainable harvest strategies. Using Atlantic silversides Menidia menidia as a model organism, we conducted a fullfactorial breeding study to measure maternal and genetic contributions to size at age through the first 2 wk of life. A total of 418 fulland half-sib families were raised in a common environment, and body lengths were recorded at 1, 5, 10, and 15 d post-hatch. Maximum likelihood was used to estimate the genetic and maternal variance components. Heritability for size at age was between 0.10 and 0.25, and increased with age. At hatch, non-genetic maternal contributions were ~7 times greater than the genetic contributions to size, but decreased with age. These significant genetic and maternal contributions to size at age indicate substantial potential to respond to selection, with subsequent population dynamic consequences.

Validating Back‐Calculation Models Using Population Data

AbstractOtolith back‐calculation, an estimation of size and growth at some previous age, is a valuable and widely used method of tracking the traits of surviving individuals. Although numerous back‐calculation models have been developed, the accuracy of model prediction is rarely assessed before using a model on wild populations. Using the Atlantic Silverside Menidia menidia, we tested the precision of four commonly used back‐calculation models (body proportional hypothesis, modified Fry, biological intercept, and time‐varying growth). We calculated the moments of the observed length frequency distribution (mean, variance, skewness, and kurtosis) and compared them with the moments of the back‐calculated length frequency distribution predicted by each model. We also compared how the most accurate back‐calculation model changed under various scenarios of size‐selective mortality and found that bias in back‐calculation could not be explained by size‐selective mortality. The differences between functional forms over a wide range of fish sizes were slight for the biological intercept and modified Fry models, whereas the time‐varying growth and body proportional hypothesis models differed considerably. We found that all models performed well for at least one measure of accuracy. However, the modified Fry model was the most accurate overall when back‐calculating to the observed population moments.

Variability in Beach Seine Samples at Small Spatial and Temporal Scales in a Near-Shore Estuarine Environment

Abstract Fish communities at nine sites in three estuaries, all emptying into Charlottetown Harbour, PE, Canada, were sampled with beach seines to assess variability at small spatial (at the same sites, between sites within estuaries, between adjacent estuaries) and temporal (minutes, hours, days, months, ebb and flood tides) scales. A total of 11 species were identified, of which two (Fundulus heteroclitus [Mummichog] and Menidia menidia [Atlantic Silverside]) made up more than 90% of the individuals captured. Samples from the same sites taken 20–30 min apart did not differ with respect to number of individuals, number of species caught, or species diversity. However, the cumulative number of species continued to increase over the first five of six samples with repeated sampling at the same location. On larger spatial scales, communities (as measured by the Global R coefficients) differed more between sites within estuaries than between adjacent estuaries. Temporal variability in fish community compositi...

Contrasting Latitudinal Variations in Vertebral Number and Sex Determination in Pacific Versus Atlantic Silverside Fishes

Organisms that are distributed across spatial climate gradients often exhibit adaptive local variations in morphological and physiological traits, but to what extent such gradients shape evolutionary responses is still unclear. Given the strong natural contrast in latitudinal temperature gradients between the North-American Pacific and Atlantic coast, we asked how increases in vertebral number (VN, known as Jordan's Rule) with latitude would differ between Pacific (Atherinops affinis) and Atlantic Silversides (Menidia menidia), two ecologically equivalent and taxonomically similar fishes with similar latitudinal distributions. VN was determined from radiographs of wild-caught adults (genetic + environmental differences) and its genetic basis confirmed by rearing offspring in common garden experiments. Compared to published data on VN variation in M. menidia (a mean increase of 7.0 vertebrae from 32 to 46°N, VN slope = 0.42 lat−1), the latitudinal VN increase in Pacific Silversides was approximately half...

Spatial scale and divergent patterns of variation in adapted traits in the ocean

The geography of adaptive genetic variation is crucial to species conservation yet poorly understood in marine systems. We analyse the spatial scale of genetic variation in traits that broadly display adaptation throughout the range of a highly dispersive marine species. We conducted common garden experiments on the Atlantic silverside, Menidia menidia, from 39 locations along its 3000 km range thereby mapping genetic variation for growth rate, vertebral number and sex determination. Each trait displayed unique clinal patterns, with significant differences (adaptive or not) occurring over very small distances. Breakpoints in the cline differed among traits, corresponding only partially with presumed eco-geographical boundaries. Because clinal patterns are unique to each selected character, neutral genes or those coding for a single character cannot serve as proxies for the genetic structure as a whole. Conservation plans designed to protect essential genetic subunits of a species will need to account for such complex spatial structures.

Egg Deposition by Atlantic Silverside, Menidia menidia: Substrate Utilization and Comparison of Natural and Altered Shoreline Type

Egg deposition by the intertidal spawning fish Atlantic silverside (Menidia menidia) was compared among six shoreline types (Spartina alterniflora, Phragmites australis, sandy beach, riprap, riprap-sill, and bulkhead) and various substrates. In spring 2010, M. menidia egg density was measured daily near Roosevelt Inlet, Delaware Bay, USA. Over 3,000,000 eggs were collected during 50 sampling days. Eggs were deposited at all six shoreline types, with >93 % of eggs collected from S. alterniflora shorelines. Choice of substrate for egg attachment was similar across shoreline types with >91 % of eggs collected from filaments of the green alga Enteromorpha spp., a disproportionately high utilization rate in comparison with Enteromorpha spp.'s relative coverage. This study demonstrates that S. alterniflora shoreline, in association with Enteromorpha spp., is the preferred spawning habitat for M. menidia and that hardened shorelines and shorelines inhabited by P. australis support substantially reduced egg densities.

Lead (Pb) in Biota and Perceptions of Pb Exposure at a Recently Designated Superfund Beach Site in New Jersey

The Raritan Bay Slag Site (New Jersey) was designated a Superfund site in 2009 because the seawall, jetties, and sediment contained lead (Pb). Our objective was to compare Pb and mercury (Hg) levels in biota and public perceptions of exposure at the Superfund and reference sites. Samples (algae, invertebrates, fish) were collected from the Raritan Bay Slag Site and reference sites and analyzed for Pb and Hg. Waterfront users were interviewed using a standard questionnaire. Levels of Pb in aquatic organisms were compared to ecological and human health safety standards. Lead levels were related to location, trophic level, and mobility. Lead levels in biota were highest at the western side of the West Jetty. Mean Pb levels were highest for algae (Fucus = 53,600 ± 6990 ng/g = ppb [wet weight], Ulva = 23,900 ± 2430 ppb), intermediate for grass shrimp (7270 ± 1300 ppb, 11,600 ± 3340 ppb), and lowest for fish (Atlantic silversides 218 ± 44 ppb). Within species, Pb levels varied significantly across the sampling sites. Lead levels in algae, sometimes ingested by individuals, were sufficiently high to exceed human safety levels. Mercury levels did not differ between the Superfund and reference sites. Despite the fence and warnings, people (1) used the Superfund and reference sites similarly, (2) had similar fish consumption rates, and (3) were not concerned about Pb, although most individuals knew the metal was present. The fish sampled posed no apparent risk for human consumers, but the algae did.

The response of correlated traits following cessation of fishery‐induced selection

The application of evolutionary principles to the management of fisheries has gained considerable attention recently. Harvesting of fish may apply directional or disruptive selection to key life-history traits, and evidence for fishery-induced evolution is growing. The traits that are directly selected upon are often correlated (genetically or phenotypically) with a suite of interrelated physiological, behavioral, and morphological characters. A question that has received comparatively little attention is whether or not, after cessation of fishery-induced selection, these correlated traits revert back to previous states. Here, we empirically examine this question. In experiments with the Atlantic silverside, Menidia menidia, we applied size-selective culling for five generations and then maintained the lines a further five generations under random harvesting. We found that some traits do return to preharvesting levels (e.g., larval viability), some partially recover (e.g., egg volume, size-at-hatch), and others show no sign of change (e.g., food consumption rate, vertebral number). Such correlations among characters could, in theory, greatly accelerate or decelerate the recovery of fish populations. These results may explain why some fish stocks fail to recover after fishing pressure is relaxed.

The Role of Submerged Aquatic Vegetation in Structuring the Nearshore Fish Community Within an Estuary of the Southern Gulf of St. Lawrence

Artificial fertilizers are contributing to the replacement of eelgrass (Zostera marina) by sea lettuce (Ulva lactuca) in estuaries of Prince Edward Island (PEI), Canada. In this study, we found that the nearshore fish community differed between areas dominated by these two vegetations within an estuary in every month sampled (April–August). Adult northern pipefish (Syngnathus fuscus), threespine stickleback (Gasterosteus aculeatus), blackspotted stickleback (Gasterosteus wheatlandi), and Atlantic silverside (Menidia menidia) were most strongly associated with eelgrass, while mummichog (Fundulus heteroclitus), ninespine stickleback (Pungitius pungitius), and American eel (Anguilla rostrata) were often more numerous in sea lettuce. Sea lettuce stations tended to have more young-of-the-year mummichog, fourspine stickleback (Apeltes quadracus), and Gasterosteus sp. than eelgrass stations but fewer young-of-the-year northern pipefish and Atlantic silverside. Fish richness and abundance were significantly lower in the sea lettuce than eelgrass habitat during August when benthic hypoxia occurred. We conclude that the loss of eelgrass from PEI estuaries will result in significant declines in fish biodiversity.

Ten polymorphic microsatellite loci for the Atlantic Silverside, Menidia menidia

Ten polymorphic microsatellite loci were isolated from the Atlantic Silverside (Menidia menidia) in order to test hypotheses regarding the role of adaptive phenotypic variation in structuring estuarine populations along coastal North America. Loci were amplified in three multiplex panels requiring a total of four individual PCRs. All loci were highly polymorphic in individuals screened from an estuary in Nova Scotia, and none exhibited significant departures from Hardy–Weinberg equilibrium. The results suggest that these loci will be sensitive to low levels of neutral divergence among populations across M. menidia populations.

Adaptation to climate change: contrasting patterns of thermal-reaction-norm evolution in Pacific versus Atlantic silversides

How organisms may adapt to rising global temperatures is uncertain, but concepts can emerge from studying adaptive physiological trait variations across existing spatial climate gradients. Many ectotherms, particularly fish, have evolved increasing genetic growth capacities with latitude (i.e. countergradient variation (CnGV) in growth), which are thought to be an adaptation primarily to strong gradients in seasonality. In contrast, evolutionary responses to gradients in mean temperature are often assumed to involve an alternative mode, 'thermal adaptation'. We measured thermal growth reaction norms in Pacific silverside populations (Atherinops affinis) occurring across a weak latitudinal temperature gradient with invariant seasonality along the North American Pacific coast. Instead of thermal adaptation, we found novel evidence for CnGV in growth, suggesting that CnGV is a ubiquitous mode of reaction-norm evolution in ectotherms even in response to weak spatial and, by inference, temporal climate gradients. A novel, large-scale comparison between ecologically equivalent Pacific versus Atlantic silversides (Menidia menidia) revealed how closely growth CnGV patterns reflect their respective climate gradients. While steep growth reaction norms and increasing growth plasticity with latitude in M. menidia mimicked the strong, highly seasonal Atlantic coastal gradient, shallow reaction norms and much smaller, latitude-independent growth plasticity in A. affinis resembled the weak Pacific latitudinal temperature gradient.

Population differences in otolith chemistry have a genetic basis in Menidia menidia

The number of studies using otolith chemistry as a tool to reconstruct the environmental history of fishes and to detect population structure continues to rise, despite the fact that factors influencing otolith deposition are not fully understood. Many studies have examined the influence of environmental parameters on otolith composition, but none to date have tested the possible influence of intrinsic factors. Using lab broodstock populations, we examined the influence of genetics and temperature on Mg:Ca, Mn:Ca, Sr:Ca, and Ba:Ca concentrations and partition coefficients in the otoliths of juvenile Atlantic silversides, Menidia menidia . Fish from two populations, South Carolina, USA, and Nova Scotia, Canada, were reared in 15, 21, and 27 °C. We found significant (p < 0.05) differences in otolith Mg:Ca, Mn:Ca, and Ba:Ca ratios as well as in Mg, Mn, and Ba partition coefficients among populations. Such genetic influences on otolith elemental concentrations have important implications for understanding the physiological mechanisms underlying otolith deposition and enhance the utility of otolith chemistry as a marker of fish population structure in the wild.

The potential use of Atlantic silverside (Menidia menidia) for monitoring estuarine pollution

Monitoring chronic impacts of nearshore pollution on fish in Atlantic marine systems is challenging due to the mobility and seasonal nature of most habitat use. We evaluated Atlantic silverside (Menidia menidia) as a potential indicator of pollution across a gradient of contaminated sites in the Saint John River Estuary, New Brunswick, Canada. Fish returning from offshore in the spring showed no differences in length, weight, or condition factor between sites, but a graded response in condition factor appeared gradually, consistent with levels of contamination. Gonad size peaked in early June, however no differences in GSI were found among sites. By September, most fish collected were young of the year, with a significant bias towards female juveniles at the exposed site. These results indicate that Atlantic silverside are locally resident during their onshore period, and demonstrates their potential as a sentinel species. Sampling should focus on early June prior to the full moon to ensure maximal exposure periods before spawning, or in late October to evaluate growth as fish grow rapidly prior to offshore movement.

High connectivity among locally adapted populations of a marine fish (Menidia menidia)

Patterns of connectivity are important in understanding the geographic scale of local adaptation in marine populations. While natural selection can lead to local adaptation, high connectivity can diminish the potential for such adaptation to occur. Connectivity, defined as the exchange of individuals among subpopulations, is presumed to be significant in most marine species due to life histories that include widely dispersive stages. However, evidence of local adaptation in marine species, such the Atlantic silverside, Menidia menidia, raises questions concerning the degree of connectivity. We examined geochemical signatures in the otoliths, or ear bones, of adult Atlantic silversides collected in 11 locations along the northeastern coast of the United States from New Jersey to Maine in 2004 and eight locations in 2005 using laser ablation inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratio monitoring mass spectrometry (irm-MS). These signatures were then compared to baseline signatures of juvenile fish of known origin to determine natal origin of these adult fish. We then estimated migration distances and the degree of mixing from these data. In both years, fish generally had the highest probability of originating from the same location in which they were captured (0.01-0.80), but evidence of mixing throughout the sample area was present. Furthermore, adult M. menidia exhibit highly dispersive behavior with some fish migrating over 700 km. The probability of adult fish returning to natal areas differed between years, with the probability being, on average, 0.2 higher in the second year. These findings demonstrate that marine species with largely open populations are capable of local adaptation despite apparently high gene flow.

Regional differentiation and post-glacial expansion of the Atlantic silverside, Menidia menidia, an annual fish with high dispersal potential.

The coastal marine environment of the Northwest Atlantic contains strong environmental gradients that create distinct marine biogeographic provinces by limiting dispersal, recruitment, and survival. This region has also been subjected to numerous Pleistocene glacial cycles, resulting in repeated extirpations and recolonizations in northern populations of marine organisms. In this study, we examined patterns of genetic structure and historical demography in the Atlantic silverside, Menidia menidia, an annual marine fish with high dispersal potential but with well-documented patterns of clinal phenotypic adaptation along the environmental gradients of the Northwest Atlantic. Contrary to previous studies indicating genetic homogeneity that should preclude regional adaptation, results demonstrate subtle but significant (F ST = 0.07; P < 0.0001) genetic structure among three phylogeographic regions that partially correspond with biogeographic provinces, suggesting regional limits to gene flow. Tests for non-equilibrium population dynamics and latitudinal patterns in genetic diversity indicate northward population expansion from a single southern refugium following the last glacial maximum, suggesting that phylogeographic and phenotypic patterns have relatively recent origins. The recovery of phylogeographic structure and the partial correspondence of these regions to recognized biogeographic provinces suggest that the environmental gradients that shape biogeographic patterns in the Northwest Atlantic may also limit gene flow in M. menidia, creating phylogeographic structure and contributing to the creation of latitudinal phenotypic clines in this species. Electronic supplementary materialThe online version of this article (doi:10.1007/s00227-010-1577-3) contains supplementary material, which is available to authorized users.

Intraspecific comparisons of metal bioaccumulation in the juvenile Atlantic silverside Menidia menidia

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 10:211-226 (2010) - DOI: https://doi.org/10.3354/ab00276 Intraspecific comparisons of metal bioaccumulation in the juvenile Atlantic silverside Menidia menidia Jessica Dutton*, Nicholas S. Fisher School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794-5000, USA *Email: dutton.jess@gmail.com ABSTRACT: We experimentally assessed the uptake, loss and resulting tissue distribution of Am, Cd, inorganic Hg(II), methylmercury (MeHg), Se and Zn in 2 North American populations (Nova Scotia and South Carolina) of juvenile Atlantic silverside Menidia menidia from aqueous and dietary sources using a radiotracer technique. Northern silversides (Nova Scotia) have a higher rate of ingestion and growth compared to their southern (South Carolina) counterparts to overcome a shorter growing season. Uptake rate constants from the dissolved phase were highest for MeHg and lowest for Cd. Assimilation efficiencies of ingested metals were highest for MeHg (82 to 89%) and lowest for Am (0.3 to 1.9%). No pronounced difference in metal uptake was noted between the 2 populations, except for MeHg after aqueous exposure, and Cd after dietary exposure, where South Carolina fish retained more metal. Elimination rate constants did not vary significantly between populations and exposure routes (except for Hg(II) after a dietary exposure) indicating that both populations process metals at the same rate. The tissue distribution of each metal in the fish varied among metals and exposure routes. Using a metal bioaccumulation model, the calculated steady-state body burden of metal was highest for Zn, and lowest for Am. Calculated body burdens were higher in South Carolina silversides for Am, Cd, and Zn. For all metals except Am, the diet is the dominant exposure route. Of the metals investigated, MeHg and Zn in both populations and Cd in the South Carolina population are expected to biomagnify at this trophic step. KEY WORDS: Metals · Fish · Bioaccumulation · Growth rate · Ingestion rate Full text in pdf format PreviousNextCite this article as: Dutton J, Fisher NS (2010) Intraspecific comparisons of metal bioaccumulation in the juvenile Atlantic silverside Menidia menidia. Aquat Biol 10:211-226. https://doi.org/10.3354/ab00276 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 10, No. 3. Online publication date: September 16, 2010 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2010 Inter-Research.

Size-dependent susceptibility of longfin inshore squid ( Loligo pealeii) to attack and capture by two predators

Cephalopods are primary prey to a wide range of predators in marine food-webs, yet a basic understanding of the mechanisms controlling predation risk and demand on their populations is lacking. Feeding experiments were conducted to evaluate how relative prey size and behavior mediate the susceptibility of squid to predation. Attack and capture of longfin inshore squid ( Loligo pealeii) were quantified using two predators: bluefish ( Pomatomus saltatrix) a pelagic, cruising predator, and summer flounder ( Paralichthys dentatus) a benthic, ambush forager. Predator selectivity, prey susceptibility, and prey profitability were estimated as a function of relative prey size from predator–prey interactions during behavioral trials. Patterns in attack rates suggested that size-selection on squid was constrained by passive processes rather than active choice for both predators. The susceptibility of squid to predation by bluefish was strongly dependent on relative prey size; however, flounder were equally efficient at capturing all sizes of squid offered. Handling times increased exponentially with relative prey size and were the primary constraint on selectivity and profitability in flounder. Prey profitability was a dome-shaped function of relative squid size in both predators. Overall, the relative size and values at which profitability was maximized were higher in bluefish indicating they were the more efficient predator of squid. Squid succumbed to greater time-dependent mortality rates than Atlantic silversides ( Menidia menidia) and mummichogs ( Fundulus sp.) suggesting that when equal amounts of squid and fish are available in the environment, squid will be selectively ingested by bluefish and flounder. In addition to the influence of relative prey size, predator foraging behaviors and size-dependent encounter rates were thought to be important factors affecting selection on squid in the northwest Atlantic ecosystem.

Ontogenesis of gonadal aromatase gene expression in atlantic silverside (Menidia menidia) Populations with genetic and temperature‐dependent sex determination

Cytochrome P450 aromatase (P450arom), an enzyme that converts testosterone to 17beta-estradiol, is an important mediator of sex determination in teleosts with genetic sex determination (GSD) and temperature-dependent sex determination (TSD). We compared the ontogenetic expression of P450arom in two populations of Atlantic silversides, Menidia menidia, which exhibit TSD (South Carolina) or GSD (Nova Scotia, Canada) using quantitative, real-time polymerase chain reaction (qRT-PCR). Embryos and newly hatched larvae were reared at an intermediate sex ratio-producing temperature (21 degrees C), and older larvae and juveniles were reared at temperatures that feminize (15 degrees C) and masculinize (28 degrees C) to assess the temperature response of P450arom during development. Before sex determination, embryos and newly-hatched larvae displayed negligible P450arom expression, indicating minimal upregulation of this gene before sex determination. Gene expression increased in both populations during sex differentiation. Nova Scotia fish with GSD exhibited presumptive male- and female-like expression levels during early sex differentiation that were not influenced by temperature. South Carolina fish displayed low levels of expression at 28 degrees C with significantly heightened expression in some individuals at 15 degrees C, indicating that P450arom is temperature sensitive in the population with TSD. Populations also differed in the timing and maximal levels of P450arom expression, with fish from Nova Scotia exhibiting both the highest and earliest increase in expression in presumptive females. Our results support the hypothesis that P450arom is involved in female sex differentiation in this species, but is only responsive to temperature in M. menidia populations that exhibit TSD.

Feeding tactics of a behaviorally plastic predator, summer flounder ( Paralichthys dentatus)

In a series of laboratory experiments, the feeding behaviors of summer flounder ( Paralichthys dentatus) were examined in response to squid and fish prey. Attack and capture tactics were evaluated for their influence on capture success, handling time, and prey-type selectivity. The ambush tactic was the primary behavior (50.6%) used to attack squid. Secondary attack types included active pursuit (42.7%) and stalking (6.7%). Regardless of the prey species targeted or the type of attack employed, summer flounder were equally efficient in capturing prey; capture success rates ranged from 50%–83%. The majority of prey were swallowed in a headfirst orientation (55.3% of squid), however swallow alignment did not significantly affect handling time. Approach times during ambush attacks were greater overall in comparison to active attacks, and relative prey size significantly affected capture times. Despite additional costs in handling time, summer flounder actively selected for mummichogs ( Fundulus spp.) (attack rate (attacks per minute) = 0.11) over longfin squid ( Loligo pealeii) (0.08) and Atlantic silversides ( Menidia menidia) (0.02). Differential attack rates favoring mummichogs suggests a preference towards demersal prey. In the presence of relatively large, fast-moving, and pelagic prey, summer flounder used a greater diversity of attack tactics than have been observed previously under controlled conditions. The behavioral plasticity exhibited by summer flounder is likely mediated by prey behavior and local availability of prey resources in inshore and offshore environments.

Description of Gyrodactylus notatae n. sp. (Monogenea: Gyrodactylidae) from Menidia menidia (L.) (Actinopterygii: Atherinidae) in Nova Scotia, Canada

Gyrodactylus notatae n. sp. (Monogenea: Gyrodactylidae) is described from the fins and gills of the Atlantic silverside Menidia menidia (L.) (Atherinidae) inhabiting the brackish water of Lawrencetown Lake, Nova Scotia, Canada. G. notatae n. sp. is the first monogenean to be reported from M. menidia. It is characterised by having stout hamuli, a ventral bar with small anterolateral processes and a linguiform membrane, a cylindrical dorsal bar, a male copulatory organ (MCO) with a single large and only three small terminal spines, and a marginal hook sickle that is wider distally than proximally. The new species most closely resembles species of the G. wageneri-group, particularly G. pungitii Malmberg, 1964, but is distinguished by the smaller dimensions of all of its haptoral components. The morphological description of G. notatae is supplemented with 1,028 sequenced base pairs (bp) of ribosomal DNA (rDNA) spanning the ITS-1, 5.8S and ITS-2 regions, with which a BLAST (Basic Local Alignment Search Tool) search failed to provide close matches (c.80%). G. notatae is only the second species of viviparous monogenean to be described from species of Menidia, the other being G. nannus Rogers, 1968 from M. beryllina (Cope) in the southern USA. The two species appear to be from different lineages within Gyrodactylus von Nordmann, 1832.