Importance of condition factor and the influence of water temperature and photoperiod on metamorphosis of sea lamprey, Petromyzon marinus. Can. j. Fish. Aquat. Sci. 58: 2448-2456.The incidence of metamorphosis of larval sea lamprey, Petromyzon marinus, was strongly affected by water temperature but not photoperiod. In a 1991 experiment, the development of metamorphosing anirnals in 13°C water was retarded about 1 mo relative to animals metamorphosing at 21 "C and to a population from the Chippetva River, Michigan; the minimum length, weight, and condition factor (CF) of metamorphosing experimental animals were 11 7 mm, 2.8 g, and 1.50, respectively, and only 4% metamorphosed at 13°C and 18.9% at 21 "C. In 1992, with a population from the Great Chazy River, New York, 66% of the animals at 13°C and 84% at 21 "C metamorphosed. The higher incidence of metamorphosis in 1992 is partly related to the use of larvae that were larger than the minima established in 1991. We predicted, using criteria defined below, that 74 and 72% of the animals at 13 and 21 "C, respectively, would metamorphose. Our predictions were consistent with observations at 13°C and for five of seven replicate tanks at 21 "C. We suggest that a presumptive metamorphosing sea lamprey in landlocked populations should be at least 120 mrn long, weigh 3.0 g, and have a CF 2 1.58 and that these criteria must be used in conjunction. L'apparition de la metamorphose des larves de la grande lamproie marine, Petromyzon marinus, etait forternent touchee par la tempkrature de I'eau, mais pas par la photoperiode. Lors d'une experience menee en 1991, If6volletion de la metamorphose des anirnaux dans de I'eau & 13 "C a kt6 retardee de 1 mo environ par rapport aux animaux qui se m6tarnorphosaitdans de I'eau a 21 "C et Bsne population de la rivigre Chippewa, Michigan; ia longueur minimale, le poids et le coefficient de condition des animaux subissant une mktarnorphose exp6rimentale btaient respectivernent de 11 7 mm, 2,8 get 1/50 et seulement 4 % des animaux se sont metamorphoses 2 13 "C et 18,9 [YO a 21 "C. En 1992, dans le cas d'une population de Is rivi&re Great Chary, New York, 66 % des animaux se sont rn6tarnorphosks 21 13 "C et 84 O/ O 2 21 'C. La frequence plus 4lev6e de m6tamorphose Fn 1992 est %iee en partie I'utilisation de larves qui 6taient plus grosses que la tailie minimale etablie en 1991. A partir des critPres dkfinis ci-dessous, nous prkvoyons que respectivement 74 et 72 % des animaux placbs respectivement dans de I'eau A 13 et 21 "C se rnetamorphoseront. Nos previsions etaient conforrnes aux observations effectuees 2 13 "C et pour cinq des sept bassiws dr6tude 3 21 "C. Selon nous, dans des populations dulcicoles, une grande lamproie marine entamerait sa rn6tamorphose 3 moins 120 mrn de longueur, pour un poids de 3,0 g et avec un coefficient de condition de 1,5Q et que ces criteres devraient &re utilises ccsnjointement.

Endocrine disruption (ED) effects due to pulp and paper mill effluents extracts involving different industrial procedures and effluent treatments (nontreated, primary, and secondary treated) were evaluated using immature triploid rainbow trout in a pulse-exposure toxicity experiment. The protocol involved the use of intraperitoneal injection of mill extracts (solid-phase extraction [SPE]) corrected for individual fish weight and included several laboratory standards (steroidal hormones and phytosterols). Biological endpoints at two different levels of biological organization were analyzed (molecular and individual organism). Results indicated that nonsignificant changes were observed in the individual physiological indices represented by condition factor, liver somatic index, and gonad somatic index during the experiment. Significant induction of liver ethoxyresorufin-O-deethylase activity was observed between different effluent treatments and experimental controls. Significant endocrine-disrupting effects at the reproductive level were observed in all effluent treatments involving significant increments in plasma vitellogenin (VTG) levels. Fish exposed to untreated effluent extracts had significantly higher VTG levels compared to fish exposed to primary and secondary treatment effluent extracts, indicating a decrease of the estrogenic effect due to the effluent treatment. The present study has shown that for the Chilean pulp and paper mill SPE extracts evaluated, an endocrine disruption effect was induced in immature triploid rainbow, reaffirming the significant estrogenic effects demonstrated previously in laboratory and field experiments.

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Metformin is currently thought to be the highest drug by weight released into the aquatic environment, as a direct result of its widespread use in the treatment of a number of human health disorders. The removal of metformin from wastewaters is directly related to the formation of guanylurea (metformin's only known persistent degradation product), which is generally present at higher concentrations in surface waters than the parent compound. With metformin use rising steadily, it is important to characterize the effects of guanylurea on nontarget aquatic organisms. We recently demonstrated the effects of developmental exposure to environmentally relevant concentrations of metformin on the growth of early life stage (ELS) medaka as well as effects on the body weight of adult male fish following full‐life cycle exposures. In the present study, we describe similar effects of guanylurea exposure on these endpoints and life stages. Guanylurea led to effects on growth in a 28‐d ELS assessment that were similar to those of metformin; however, these effects occurred at concentrations in the ng/L range compared with the μg/L range for metformin. A possible sex‐dependent association with body weight changes was also observed in adults following a 165‐d full‐life cycle exposure to guanylurea alone or in a mixture with metformin. To our knowledge, the present is the first study to report the toxicity of guanylurea to nontarget aquatic organisms. Environ Toxicol Chem 2019;00:1–6. © 2019 SETAC

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