Are meiofauna a standard meal for macroinvertebrates and juvenile fish?

Abstract The primary goal of this study was to investigate the possibility of using early life stages of white sturgeon (Acipenser transmontanus) (eggs, larvae and fry) as a species relevant to the Fraser River, B.C., for the acute and sublethal toxico-logical testing of forest industry effluents. Here we report the first successful acute toxicity tests for 8-day-old larvae and 42-day-old fry exposed to several chemicals known to be released into the Fraser River (i.e., 6 monochlorovanillin [6 MVAN], 4,5 dichloroguaiacol [4,5 DCG], 4,5 dichlorocatechol [4,5 DCAT], pentachlorophenol [PCP], and didecyldimethylammonium chloride [DDAC]). In most cases, white sturgeon fry were at the lower end of the range for acute toxicity values for chlorinated phenolic compounds, when compared with other juvenile fish species, and they were extremely sensitive to DDAC. The larval stage was usually more sensitive than the fry stage. Acute toxicity tests with fertilized eggs were unsuccessful. A postexposure growth study was inconclusive because neither control nor toxicant-exposed larvae and fry withstood the additional handling used for measuring body mass. At 62-days-old, fry were more tolerant of handling. This allowed measurement of their swimming performance. Although we have concerns about the reliability of using larvae for acute toxicity testing at this time, 60-day-old white sturgeon fry would appear to be both a sensitive and relevant species for assessing environmental impacts relevant to the Fraser River.

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Juvenile fish assemblages in the Jinju Bay region, Korea

Fisheries and Aquatic Sciences ◽

10.1186/s41240-020-00175-6 ◽

2020 ◽

Vol 23 (1) ◽

Author(s):

Se Hun Myoung ◽

Seok Nam Kwak ◽

Jin-Koo Kim ◽

Won-Chan Lee ◽

Jeong Bae Kim ◽

...

Keyword(s):

Dominant Species ◽

Fish Assemblages ◽

Juvenile Fish ◽

Young Fish ◽

Monthly Basis ◽

Southern Korea ◽

Pleuronichthys Cornutus ◽

Pennahia Argentata ◽

Hemitripterus Villosus ◽

Number Of Individuals

AbstractAssemblages of juvenile fish and associated abiotic parameters were investigated inside and outside Jinju Bay in southern Korea, on a monthly basis from December 2014 to November 2015. Fluctuations in water temperature and salinity were larger inside than outside the bay. In total, 534,657 individuals per square kilometre from 81 fish species and 47 families were collected during the study period. The most dominant species was Nuchequula nuchalis both inside (25.6%) and outside (26.9%) the bay. The next dominant species were Thryssa kammalensis (17.9%) and Zoarces gillii (16.0%) inside the bay and Liparis tanakae (16.9%) and T. kammalensis (9.0%) outside the bay. Forty species (33% of total number of individuals) of young fish were recorded inside the bay and 47 species (52%) outside the bay. Therefore, it appears that a diversity of fish use nursery grounds inside and outside Jinju Bay. In particular, the following six species appeared: Z. gillii, Pleuronichthys cornutus, L. tanakae, Hemitripterus villosus, Pennahia argentata, and Xenocephalus elongates. Due to assemblage differences for fishes within Jinju Bay and outside the bay, management of both areas is required to maintain current diversity of species in the region.

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The diet and growth of juvenile fish in a gravel pit lake

SIL Proceedings 1922-2010 ◽

10.1080/03680770.1987.11898092 ◽

1988 ◽

Vol 23 (3) ◽

pp. 1719-1723

Author(s):

M. P. Cook ◽

M. J. Burgis

Keyword(s):

Juvenile Fish ◽

Pit Lake ◽

Gravel Pit

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The β-oxidation pathway is downregulated during diapause termination in Calanus copepods

Scientific Reports ◽

10.1038/s41598-019-53032-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Elise Skottene ◽

Ann M. Tarrant ◽

Anders J. Olsen ◽

Dag Altin ◽

Mari-Ann Østensen ◽

...

Keyword(s):

Current Knowledge ◽

Juvenile Fish ◽

Sampling Site ◽

Geographical Location ◽

Keystone Species ◽

Calanoid Copepods ◽

Diapause Termination ◽

Molecular Events ◽

High Lipid ◽

Field Samples

Abstract Calanus copepods are keystone species in marine ecosystems, mainly due to their high lipid content, which is a nutritious food source for e.g. juvenile fish. Accumulated lipids are catabolized to meet energy requirements during dormancy (diapause), which occurs during the last copepodite stage (C5). The current knowledge of lipid degradation pathways during diapause termination is limited. We characterized changes in lipid fullness and generated transcriptional profiles in C5s during termination of diapause and progression towards adulthood. Lipid fullness of C5s declined linearly during developmental progression, but more β-oxidation genes were upregulated in early C5s compared to late C5s and adults. We identified four possible master regulators of energy metabolism, which all were generally upregulated in early C5s, compared to late C5s and adults. We discovered that one of two enzymes in the carnitine shuttle is absent from the calanoid copepod lineage. Based on the geographical location of the sampling site, the field-samples were initially presumed to consist of C. finmarchicus. However, the identification of C. glacialis in some samples underlines the need for performing molecular analyses to reliably identify Calanus species. Our findings contributes to a better understanding of molecular events occurring during diapause and diapause termination in calanoid copepods.

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