Larval Length Research Articles

Influence of parasitoid Paravilla sp. (Diptera, Bombyliidae) on the development of larvae of Myrmeleon brasiliensis (Návas, 1914) (Neuroptera, Myrmeleontidae)

Parasitoids manipulate the host metabolism for their own benefit by influencing its development and the direct or indirect result of it is the host death. This study aimed to observe the influence of parasitoidism of Paravilla sp. (Diptera, Bombyliidae) on the development of antlion larvae Myrmeleon brasiliensis (Návas, 1914) (Neuroptera, Myrmeleontidae). The specific objectives were to verify in which larval instars the parasitoid oviposition occurs, the influence of the parasitoid on the larval and pupal development time of M. brasiliensis, the differences in body length of the antlion larvae, as well as of the sex ratio of M. brasiliensis adults. For this, the larvae were differentiated in 1st, 2nd and 3rd instar and measures on body length (head-abdomen) and accompanied until the emergence of the adult. It was observed that the parasitoid Paravilla sp. attacked only the 2nd and 3rd instar larvae. The parasitoid Paravilla sp. oviposited only in 2nd and 3rd instars larvae. No significant differences were observed on larval development time, in the larval body length and in the adult sex ratio between groups of parasitized and non-parasitized M. brasiliensis larvae, however, was observed differences in the pupal development time of these two groups. Thus, we can conclude that the parasitoid Paravilla sp. influences the development time of M. brasiliensis pupal.

Spatial variability in post-larval traits of Sicyopterus lagocephalus Pallas 1770 around Reunion Island

The spatial variability of S. lagocephalus post-larval traits, in February 2015, was investigated through comparison of pelagic larval duration (PLD), standard length (SL), body mass (BM) and condition factor among 6 rivers around Reunion Island. The variability of the same traits was also investigated within a recruitment event in another river, in January 2015. Our results showed homogeneity of the PLD both between sites during the recruitment of February 2015, and during the recruitment event of January 2015 at a given site. The other traits were different between the eastern and the western rivers. The post-larvae from the East were characterised by higher BM and condition factor whereas on the West they were longer. These differences can be explained by different environmental conditions experienced by larvae in the coastal oceanic water before they entered the river, but also by different migration routes during their marine dispersal. The coastal water on the eastern side, more turbid and probably trophically richer, could have induced a better growth of the post-larvae compared to those at the same age on the western side. A singularity was highlighted concerning the Marsouins River, located East of the island, where post-larvae were at a more advanced stage of their metamorphosis, characterised by both a smaller size and a lighter weight. This particularity was related to the location of the fishermen trapnet, positioned farther up river compared to all the other rivers, either West or East of the island.

Variation in Pond Hydroperiod Affects Larval Growth in Southern Leopard Frogs, Lithobates sphenocephalus

Size at metamorphosis is an important correlate of amphibian fitness. Several, often interrelated factors, such as hydroperiod, competition, and food availability, determine metamorph size. Hydroperiod is a defining characteristic of ponds, but pond drying is not always a deterministic process, and refilling can occur prior to complete drying. We conducted an experiment to test if a recurring four-week partial drying/filling cycle affected amphibian growth and size using a population of overwintering larval Lithobates sphenocephalus (Southern Leopard Frogs). Effects of the drying/filling cycle varied over time on larval mass, but this cycle had no overall effect on other measures of larval or metamorph size. Metamorph size covaried with both survival and larval period length: individuals were larger at metamorphosis when survival was lower and among individuals with longer larval periods. We observed the first reported instance of prolonged larval periods across multiple winters in L. sphenocephalus, wherein some of our larvae exposed to the drying/filling cycle required 18 months to reach metamorphosis. Individuals that overwintered as larvae for a second winter were larger at metamorphosis than those that metamorphosed at the end of the previous summer. Lithobates sphenocephalus maximize metamorphic size rather than optimize metamorphic timing, and metamorph size can also be affected by larval survival.

Lethal and sublethal effects of metal-polluted sediments on Chironomus sancticaroli Strixino and Strixino, 1981.

The Cantareira Complex is one of the most important water supplies of the metropolitan region of São Paulo, Brazil. Previously, it was demonstrated that the sediments in this complex were polluted with metals and that Paiva Castro Reservoir-the last reservoir in the sequence, which receives water from the five previous reservoirs-was the reservoir with the greatest concentration of pollutants. Based on field data, it was noticed that copper concentrations in sediments were related to morphological alterations in chironomids. The present study provides novel monitoring methods and results for the complex by isolating the environmental and biological sources of variation. An adaptation of the in situ assay proposed by Soares et al. (Arch Environ Contam Toxicol 49:163-172, 2005), which uses a native tropical Chironomus species and low-cost materials, is also provided. The aim of this study was to isolate the effects of sediments from Paiva Castro on controlled populations of C. sancticaroli larvae using an in situ assay. A seven-day experiment was performed in triplicate. Third instar larvae were inoculated in chambers containing sediments from two distinct regions of Paiva Castro reservoir and a control site with sand. Five biological responses were considered: mouthpart alterations, larval length, width of cephalic capsule, mortality and total damage. The results suggest the effects of sediment toxicity on larvae include a reduction in length and a higher occurrence of total damage.

The Effect of Burned Liver on the Length, Weight and Development of Megaselia scalaris (Loew) (Diptera: Phoridae) – A Preliminary Assessment and Implications in Forensic Entomology

Development of insects in laboratory for minimum post mortem interval estimation (mPMI) or time of colonisation (TOC) in forensic entomology can be affected by the type and quality of food consumed during larval period. Since mPMI estimation also involves analysis of larval specimens collected from burned human remains, it is important to study if burned tissues could affect growth of sarcosaprophagous larvae. This study investigated the effect of burned tissues on the size and developmental period of Megaselia scalaris (Loew) (Diptera: Phoridae), a species of forensic importance. Development of M. scalaris on 75 g burned cow’s liver was compared with control liver in three study replicates. Mean larval length (2.87 ± 0.11 mm) and weight (0.81 ± 0.08 mg) of M. scalaris larvae in burned liver diets were significantly lower than larval length (5.03 ± 0.15 mm) and weight (2.85 ± 0.21 mg) of control liver diets (p < 0.001) whilst mean pupal length (2.53 ± 0.06 mm) and weight (0.92 ± 0.06 mg) in burned liver diets were significantly lower than pupal length (3.52 ± 0.06 mm) and weight (2.84 ± 0.16 mg) in control liver diets (p < 0.001). Development of larvae in burned liver was 5-9 hours slower than those feeding on control liver based on single observation. Although the assessment is preliminary, the findings indicate physical growth of larvae feeding on burned animal tissues was affected and entomological specimens recovered from burned remains should be evaluated carefully to avoid errors in mPMI/TOC estimation. Limitations and suggestions for further research are also presented herein. DOI : http://dx.doi.org./10.17576/JSKM-2018-1601-04

Characterizing larval swordfish habitat in the western tropical North Atlantic

AbstractSwordfish Xiphias gladius (Linnaeus, 1758) are a circumglobal pelagic fish targeted by multiple lucrative fisheries. Determining the distribution of swordfish larvae is important for indicating reproductive activity and understanding the early life history of swordfish. We identify and characterize larval swordfish distributions during peak swordfish spawning throughout the Gulf of Mexico and western Caribbean Sea with generalized additive models (GAMs) using catches of swordfish larvae during ichthyoplankton surveys in April and May of 2010, 2011, and 2012. The best fit GAM, as determined by stepwise, backward Akaike Information Criterion selection, included both physiochemical (temperature at 5 m, sea surface height anomaly (SSHA), eddy kinetic energy (EKE)), temporal (lunar illumination, hour of sampling) and spatial (location) variables, while near surface chlorophyll a concentration residuals remained as a random effect. The highest probability of larval swordfish catch occurred at sub‐surface temperatures, SSHA, and EKE values indicative of boundary currents. Standard lengths of larvae were larger further downstream in the boundary currents, despite high variability in length with location due to multiple spawning locations of swordfish near these currents. Probability of larval swordfish catch also peaked during the crescent and gibbous moons, indicating a lunar periodicity to swordfish spawning. These results suggest that swordfish may spawn during select moon phases near boundary currents that transport their larvae to larval and juvenile habitat including the northern Gulf of Mexico and coastal waters of the southeast United States.

Impact of Ocean Acidification and Warming on the bioenergetics of developing eggs of Atlantic herring Clupea harengus.

Atlantic herring (Clupea harengus) is a benthic spawner, therefore its eggs are prone to encounter different water conditions during embryonic development, with bottom waters often depleted of oxygen and enriched in CO2. Some Atlantic herring spawning grounds are predicted to be highly affected by ongoing Ocean Acidification and Warming with water temperature increasing by up to +3°C and CO2 levels reaching ca. 1000 μatm (RCP 8.5). Although many studies investigated the effects of high levels of CO2 on the embryonic development of Atlantic herring, little is known about the combination of temperature and ecologically relevant levels of CO2. In this study, we investigated the effects of Ocean Acidification and Warming on embryonic metabolic and developmental performance such as mitochondrial function, respiration, hatching success (HS) and growth in Atlantic herring from the Oslo Fjord, one of the spawning grounds predicted to be greatly affected by climate change. Fertilized eggs were incubated under combinations of two PCO2 conditions (400 μatm and 1100 μatm) and three temperatures (6, 10 and 14°C), which correspond to current and end-of-the-century conditions. We analysed HS, oxygen consumption (MO2) and mitochondrial function of embryos as well as larval length at hatch. The capacity of the electron transport system (ETS) increased with temperature, reaching a plateau at 14°C, where the contribution of Complex I to the ETS declined in favour of Complex II. This relative shift was coupled with a dramatic increase in MO2 at 14°C. HS was high under ambient spawning conditions (6-10°C), but decreased at 14°C and hatched larvae at this temperature were smaller. Elevated PCO2 increased larval malformations, indicating sub-lethal effects. These results indicate that energetic limitations due to thermally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.

Survey of museum beetle (Dermestes sp.) damage to the scorpion collection in the Health Faculty of Kashan University of Medical Sciences

The result showed that all the drawers containing the scorpion preservation boxes were found damaged by Dermestes sp. Totally, 210 Dermestes larvae were collected. On a average 15 larvae were collected from each drawer. The length of the mature larva was 10–12 mm. The larvae were oval shaped with bodies covered hearly by strands of hair. The incurred damages to the collections were huge because of lack of supervision.

Influence of some polygonaceous plants on biology of Galerucella placida baly (Coleoptera: Chrysomelidae)

Biology of leaf beetle, Galerucella placida Baly was studied on eight polygonaceous plants, which indicated that body length and width of 1st-3rd instar larvae was maximum on Polygonum hydropiper (L.) Spach. and minimum on Polygonum perfoliatum L. Pupal length and width was maximum (4.58 mm and 2.37 mm) on P. hydropiper (L.) Spach. and minimum (4.10 mm and 2.05 mm) on P. perfoliatum L. The maximum length and width of male (5.60 mm and 2.35 mm) and female (6.25 mm and 2.50 mm) was recorded on P. hydropiper (L.) Spach. and minimum (5.10 mm and 2.00 mm) for male and (5.50 mm and 2.15 mm) for female on P. perfoliatum L. Similarly, shortest larval (13.12 days) and pupal duration (4.46 days), and highest fecundity (431.60 eggs/female) was recorded on P. hydropiper (L.) Spach. The maximum larval (17.25 days) and pupal duration (4.76 days), and lowest fecundity (163.00 eggs/female) were observed with P. perfoliatum L. These observations indicate the scope for use of G. placida as a biocontrol agent against P. hydropiper, since it was found the most suitable host plant in comparison to other polygonaceous plants.

Ảnh hưởng của việc bổ sung hàm lượng lecithin khác nhau trong thức ăn đến sự biến thái và tỉ lệ sống của cua biển (Scylla paramamosain) từ giai đoạn zoea 3 đến cua 1

The study was conducted to deterimne the suitable supplementation level of lecithin in formulated feeds for larvae of mud crab, Scylla paramamosain consisting of two rearing phases. (1) From zoea 3 to megalopal stage, (2) From megalopal stage to crablet 1. The experiment was completely randomized with 5 replications of five feeding treatments. The test diets had isonitrogenous (53%), isolipid (12%), were supplemented with different lecithin levels of 0% (control diet), 1%, 2%, 3% and 4%. Crab larvae were co-fed Artemia and experimental feeds during larval rearing period. The results showed that when rearing from zoea 3 to megalop stage, which received the diet supplemented with 3% lecithin gave significantly higher larval stage index, survival, length and weight) of megalopa than those in the control diet. When rearing from megalopal stage, the carapace width, weight and survival of crablet1 inthe 3% lecithin group were highest and significantly different from other feeding treatments except the 2% and 4% lecithin treatments for survival. These results suggested that formulated feeds supplemented with 3% lecithin could be considered the suitable level for larval rearing of mud crab S. paramamosain.

Do models parameterized with observations from the system predict larval yellow perch (Perca flavescens) growth performance better in Lake Erie?

Growth performance can influence survival during early life. As such, a range of statistical to mechanistic modeling approaches has been used to predict growth performance, with few studies evaluating prediction accuracy. We tested the ability of three models to estimate observed larval yellow perch (Perca flavescens) growth and length in western Lake Erie (United States – Canada). We found that a general linear model developed using yellow perch data from western Lake Erie performed best followed closely by a semimechanistic individual-based model (IBM) specific to Lake Erie yellow perch and worse by a general multispecies IBM. We suspect that the statistical model performed better because, unlike IBMs, it does not require prey availability data, probably poorly represented by zooplankton samples, and because the IBMs are imperfectly parameterized. Our findings indicate that caution should be exercised when using general IBMs given that the models parameterized with observations from the system of interest outperformed the general IBM in providing accurate fish growth and length estimates, pointing to the need for research that can improve existing mechanism-based models of larval growth.

The Regulatory Effect of Low-Intensity Radiation in the Near-Infrared Region on the Early Development of Zebrafish (Danio rerio)

The effects of exposure to low-intensity continuous radiation in the red and near-infrared regions of the spectrum, as well as to infrared pulsed radiation, on the early development of zebrafish (Danio rerio) were studied. It was found that the use of continuous radiation at the red and infrared wavelengths (633 nm, 930 nm, dose 24 mJ/m2) leads to accelerated development of the embryo. In contrast, exposure to low-intensity single pulsed infrared radiation (864 nm) in the entire range of the doses studied (2.4–2400 mJ/cm2) negatively affected the early development of zebrafish, resulting in a significant dose-dependent delay in the hatching time of embryos and a reduction in the body length of larvae.

Biology of potato tuber moth Phthorimaea operculella on potato varieties

Laboratory evaluation was carried out in the Department of Entomology, College of Agriculture, Central Agricultural University, Imphal to study the biology and ovipositional preference of Phthorimaea operculella on five potato varieties namely, Kufri Girdhari, Kufri Himalini, Kufri Jyoti, Kufri Kanchan and Kufri Sindhuri. The results revealed that the fecundity was maximum when moths were reared as larvae on Kufri Kanchan, followed by K. Jyoti> K. Girdhari> K. Himalini>K. Sindhuri. The total lifecycle was maximum when larvae were fed on K. Himalini and the least with K. Sindhuri. The larval length varied with the varieties: larvae fed on Kufri Kanchan were longer (11.76 mm) and those fed on Kufri Sindhuri were short (6.48 mm). The egg size, larval breadth, pupal size and adult length did not show any significant variation. Amongst the varieties, K. Jyoti and K. Kanchan were the most preferred ones for oviposition, while the moderately preferred were K. Girdhari and K. Himalini and the least preferred was K. Sindhuri.

Temporal variability in offspring quality and individual reproductive output in a broadcast-spawning marine fish

AbstractThe protracted spawning period of broadcast-spawning marine fishes has potential to generate considerable variability in metrics of individual reproductive output. We undertook a temporally detailed genetic study of larvae produced by Atlantic cod (Gadus morhua) from two spatially proximate populations spawning under controlled semi-natural conditions over 94 days. Based on daily samples of larvae (n = 4489 in total), we document fine-scaled temporal changes in, and correlates of, offspring phenotype and reproductive output (egg batches produced or fertilized). Larval length and standardized yolk-sac volume declined 11 and 49% over the spawning period, respectively. The adaptive significance of these trends is unclear. Longer, heavier females produced longer, better-provisioned larvae. Body size affected the number of egg batches to which an individual contributed genetically but not spawning duration. Males contributed gametes to a greater number of egg batches (19.5 vs. 9.2), and spawned over a longer period of time (48.9 vs. 30.8 days), than females. After accounting for body size and condition, egg batch number and spawning duration differed between adjacent populations separated by &amp;lt; 10 km. Our work highlights the need to understand the environmental and adaptive causes of temporal variability in offspring quality and its consequences to individual fitness and per capita population growth in batch-spawning fishes.

Early Development of the Threespine Stickleback in Relation to Water pH

Ocean acidification is a growing environmental problem, and there is a need to investigate how the decreasing pH will affect marine organisms. Here we studied the effects of lowered pH on the growth and development of the threespine stickleback (Gasterosteus aculeatus) eggs. Adult fish, collected from the natural environment, were allowed to mate in aquaria and the newly produced eggs were incubated in an experiment. Eggs and larvae from ambient conditions (produced in the laboratory) were reared at three different pH concentrations (control: pH 7.8; and reduced pH treatments: pH 7.5 and 7.0) for 21 days in the laboratory. Dissolved oxygen concentration (8.1 ± 0.1 mg l-1) and temperature (18.6 ± 0.02°C) were monitored regularly. Then, egg diameter, larval length, weight and survival were measured. There was no relationship between egg diameter and pH or oxygen, but a negative relationship was found with temperature. Survival of larvae was not affected by pH or temperature, whereas dissolved oxygen concentration had a positive effect on number of survivors. The pH did not have a significant effect on the final larval length on day 21, but interacted significantly with dissolved oxygen. Higher temperatures were found to have a positive effect on the final larval length and weight. Larval weight, on the other hand, was not related to pH nor oxygen. Coastal zones are characterized by pH levels that fluctuate due to natural processes, such as upwelling and river runoff. Our results suggest that the threespine stickleback larvae are well adapted to the different pHs tested, and egg development will likely not be affected by decreasing pH, but even slight temperature and oxygen changes can have a great impact on the threespine stickleback development.

Development of Chrysomya megacephala at constant temperatures within its colony range in Yangtze River Delta region of China

ABSTRACTChrysomya megacephala (Fabricius, 1794) is the most abundant and predominant species which arrives and colonizes a cadaver first in most parts of China. Therefore, its growth and development patterns have great implications in the estimation of the minimum postmortem interval (PMImin). In this study, C. megacephala was collected from the Yangtze River Delta region and reared at seven constant temperatures ranging from 16 °C to 34 °C. The developmental duration and accumulated degree hours, larval body length and morphological changes of C. megacephala were examined. Furthermore, we constructed three developmental models, isomorphen diagram, isomegalen diagram and thermal summation model, which can be used for estimating PMImin. The developmental durations of C. megacephala at 16 °C, 19 °C, 22 °C, 25 °C, 28 °C, 31 °C and 34 °C are (794.8 ± 14.7), (533.2 ± 10.1), (377.8 ± 16.8), (280.8 ± 15.1), (218.9 ± 8.5), (190.8 ± 10.1) and (171.8 ± 6.8) h, respectively. The developmental threshold temperature D0 is (11.41 ± 0.32) °C, and the thermal summation constant K is (3 418.7 ± 137.0) degree hours. Regression analysis was conducted to obtain equations of the variation in larval body length with time after hatching, and variation in time after hatching with body length. Moreover, our study divides the intra-puparial morphological changes of C. megacephala into 11 sub-stages, and provides the time range experienced by each sub-stage. The results of this study provide fundamental development data for the use of C. megacephala in PMImin estimations.

Effects of the antidepressant, mianserin, on early development of fish embryos at low environmentally relevant concentrations

Pharmaceuticals have been considered as emerging organic contaminants in the environment that might pose huge risk to the non-target aquatic organisms. Mianserin, a tetracyclic antidepressant, is present at low detectable concentrations in the aquatic environment; however, limited attention has been devoted to its potential adverse effects on the aquatic animals. In the present study, we first performed an acute toxicity test for mianserin exposure using zebrafish (Danio rerio) embryos during 4–124h post fertilization (hpf). Time-dependent lethal concentrations of mianserin exposure on the zebrafish embryos were firstly determined at mg/L levels. Then, a series of sublethal concentrations of 0.01, 0.1, 1, 10, 100, and 1000μg/L of mianserin were prepared for the short-term exposure of zebrafish embryos for 120h. The results showed that mianserin exposure reduced the body length of zebrafish larvae, in addition to altering multiple physiological and biochemical parameters in the exposed embryos/larvae. A dose-dependent inhibition of the total antioxidant capacity and total cholinesterase activity was revealed in the exposed fish larvae upon increasing the concentrations of mianserin exposure. A U-shaped concentration-dependent response curve was observed for the adrenocorticotropic hormone; however, an inversed U-shaped response curve was obtained for the monoamine oxidase level in response to mianserin exposure. Activities of the total adenosine triphosphatase (T-ATPase), Na+/K+-ATPase, and Ca2+/Mg2+-ATPase were significantly increased in the fish larvae exposed to relatively high doses of mianserin; interestingly however, low dose of mianserin at 10ng/L inhibited their Na+/K+-ATPase and T-ATPase activities. Additionally, the coordinated regulation of cyclic adenosine monophosphate and protein kinase A was observed in the mianserin-exposed fish larvae, implying a reserved signaling pathway involved in the fish response to the antidepressant. Therefore, our study demonstrated that mianserin exposure significantly affected the early development of fish embryos at environmentally relevant concentrations, and suggested that the risk of pharmaceutical contamination of the aquatic environment, even at low doses, should receive more attention.

Post-cooling survival, growth and deformity rates in zebrafish embryos (Danio rerio).

This study investigated and analysed survival, growth and macro- and microscopic damage during the development of zebrafish embryos up to the adult stage after undergoing cooling. The embryos at 50% epiboly stage were selected, submerged in cryoprotectant solution of methanol and sucrose, cooled gradually to 0 ± 2°C temperature, and divided into two groups with different storage times (6 and 18 h). Subsequently, the embryos were reheated, rehydrated and incubated normally. The experiment lasted 5 months and, from hatching onward, the larvae were examined, collected and processed at pre-established time intervals. The hatching rate was significantly higher for the larvae stored for 18 h compared with the 6-h group. However, embryos from this group gave rise to a larger number of malformations, and these were much more severe compared with those in the 6 h group, which led to a higher mortality in the long term. Regarding larval length, the animals of the 6 h group had higher mean total length compared with the 18 h group, but both treatments were inferior to the control. Numerous macro- and microscopic malformations were observed and, in both treatments, only the morphologically normal individuals were able to develop to the adult stage, with organ development similar to the control, except for the gonads that were still undifferentiated in treated animals.

Morphological Development of Eggs, Larvae and Juveniles of the Far Eastern Catfish, Silurus asotus in Korea (Pisces: Siluridae).

ABSTRACTThis study was conducted to investigate egg development and larvae morphological development of catfish and to provide basic data to clarify the genetic relationship with Siluriformes fish. The mother fish that was used in this study was caught in the stream of Nakdong River in Uiseong-gun, Gyeongbuk. The temperature range of the breeding was 23.0-25.0℃ (mean 24.0±1.0℃) and egg size was 1.62-1.70 mm (mean 1.66±0.05, n=30). Eggs of catfish began hatching at 54 hours and 40 minutes after fertilization. Immediately after hatching, the total length of larvae was 3.60-3.65 mm (mean 3.62±0.03, n=5) and had an egg yolk without swimming ability. On the third day after hatching, the larvae at the medium stage was 8.00-8.65 mm (mean 8.32±0.45) in total length, and two pairs of whiskers formed around the mouth were elongated. On the 12th day after hatching, the larvae at the juvenile stage was 16.5-17.0 mm (mean 16.7±0.35) in total length, and the stem of each fin was in the range, and the juvenile at this period was morphologically similar to the mother fish.

Spatial and Ontogenetic Variation in Mercury in Lake Superior Basin Sea Lamprey (Petromyzon marinus).

Mercury concentrations were measured in eggs, larvae, and adult spawning-phase sea lampreys (Petromyzon marinus) collected in tributaries of Lake Superior to investigate spatial and ontogenetic variation. There were significant differences in mercury concentrations between all three life stages, with levels highest in adults (mean = 3.01µg/g), followed by eggs (mean = 0.942µg/g), and lowest in larvae (mean = 0.455µg/g). There were no significant differences in mercury concentrations by location for any life stage or by sex in adults. Mercury was not correlated with adult or larval lamprey length or mass. Mercury levels in adult lampreys exceeded U.S. and Canadian federal guidelines for human consumption. Mercury concentrations in all life stages exceeded criteria for the protection of piscivorous wildlife, posing a threat to local fish, birds, and mammals. High mercury levels in adult lampreys combined with their semelparous life history make them a potential source of lake-derived mercury to spawning streams.