Паразиты рыб горных озер бассейна Верхней Колымы. 1. Озера большой и малый Дарпир.

The first data on the parasite fauna of fish from the mountain lakes Bolshoy and Maly Darpir at the southern spurs of the Chersky Ridge (Momsky District, Yakutia) are presented. 7 species of fish have been studied, in which 34 species of parasites have been found: 33 species of helminths and 1 species of parasitic copepods, belonging to 22 genera, 16 families, 12 orders, 7 classes of 4 types of the animal kingdom. Trematodes completely dominate by the number of species among helminths (16 species); cestodes are half as many (8 species); these are followed by nematodes and spiny-headed worms (5 and 4 species, respectively). The greatest variety of parasites was found in the East Siberian grayling (22 species) and the Arctic char (19 species). Next to the latter in terms of the number of parasite species, there went the Kolyma sculpin (13 species), round whitefish (10 species each), sucker (9 species), eelpout, and common minnow (7 species each). Only one parasite species, the Neoechinorhynchus salmonis Ching, 1984 spiny-headed worm, is common for all studied fish. The second species of spiny-headed worms, Pseudoechinorhynchus borealis (Linstow, 1901), not found only in the round whitefish, was first recorded in fish of the Okhotsk-Kolyma area and in the sucker as a new definitive host.

Using DNA barcoding to identify host-parasite interactions between cryptic species of goby (Coryphopterus: Gobiidae, Perciformes) and parasitic copepods (Pharodes tortugensis: Chondracanthidae, Cyclopoida)

Previous work, using morphological characters, identified a generalist copepod parasite (Pharodes tortugensis) at high prevalence on two common gobies (Coryphopterus glaucofraenum and C. dicrus) in the British Virgin Islands (BVI). DNA barcoding subsequently revealed C. glaucofraenum to be three morphologically similar species (C. glaucofraenum, C. venezuelae and C. tortugae), casting doubt on host identities in the BVI and the classification of the parasite as a single species. Mitochondrial cytochrome c oxidase subunit I (COI) data from 67 gobies in the BVI showed that, in addition to C. dicrus, host gobies were a mix of C. glaucofraenum and C. venezuelae, while C. tortugae was unexpectedly absent from the study area. COI data (n = 70) indicated that the copepod infecting all three hosts was a single species, almost certainly P. tortugensis. The pharodes-coryphopterus interaction has a strong impact on host dynamics in the BVI, and a revised understanding of these dynamics must account for any differences among the three newly confirmed hosts in transmission of, and susceptibility to, the shared parasite. No other infected hosts were discovered at our sites, but P. tortugensis is reportedly widespread and infects 12 additional host species elsewhere. Further DNA barcoding is thus needed to test whether P. tortugensis is truly a widespread generalist, or instead represents a group of more specialized cryptic species.

An overview of fish disease and parasite occurrence in the cage culture of Oreochromis niloticus: A case study in Lake Victoria, Kenya

Cage aquaculture has been on a steady rise in Lake Victoria, Kenya, since 2016, resulting in the current culturing of over 3,600 cages of Tilapia (O. niloticus) (Orina et al., 2018). Unfortunately, there has been limited, if any, focus on fish health aspects. Rise in intensification and commercialization predisposes fish stocks to disease due to rise in stress levels and consequent reduction in the fish immunity. Nutrient rich surroundings create a conducive environment for rapid proliferation of bacterial and saprophytic fungal growth leading to net clogging and consequently a low biological oxygen demand. Such conditions predispose the stocks to infections. This study was conducted to provide a baseline analysis of the health conditions/status of the cultured fish in this region. It encompassed studies from 2016 to 2018 on tilapia of the genus O. niloticus using both experimental (using standard procedures and protocols) and socio-economic studies (using structured questionnaires, see annexure 1). Results found the following occurrences; bacterial infections (10%), fungal infestations (12.5%), myxosporean parasites in the gills (5%), parasitic copepods (10%) and fin rot (2.5%) in the stocks. There were no significant differences between abiotic parameters in the cage locations and the wild (p > 0.05). Additionally, 90% of the respondents had no fish disease training or clue on the treatment action necessary whenever fish diseases struck. Findings from this study put to the fore the significance of fish diseases in a cage culture system in light of commercialization of the industry and the importance of biosecurity and maintenance of optimal environmental conditions within the scope of Blue Economy growth in this region. This study did not detect any disease or parasite of zoonotic importance.

Parasitic copepods of the family Lernanthropidae Kabata, 1979 (Copepoda: Siphonostomatoida) from Australian fishes, with descriptions of seven new species

The total number of species of Lernanthropidae previously recorded from Australian waters is 15 (i.e., one species each of Aethon Krøyer, 1837, Lernanthropodes Bere, 1936, and Lernanthropsis Do, in Ho & Do, 1985; 10 species of Lernanthropus de Blainville, 1822; and two species of Sagum Wilson, 1913), and all of these records are reviewed. We report here the presence of three species of Aethon. One species, A. garricki Hewitt, 1968, is reported from Australian waters for the first time and a new species, A. bicamera sp. nov., is described from the latrid, Latris lineatus (Forster, 1801) caught off South Australia. The genus Lernanthropodes is represented by a single species, L. trachinoti Pillai, 1962. We recognize Chauvanium Kazachenko, Kovaleva, Nguyen & Ngo, 2017 as a subjective synonym of Lernanthropodes and transfer its type and only species C. chauvani Kazachenko, Kovaleva, Nguyen & Ngo, 2017 which becomes Lernanthropodes chauvani (Kazachenko, Kovaleva, Nguyen & Ngo, 2017) n. comb. Lernanthropsis mugilii (Shishido, 1898) is reported here from Mugil cephalus Linnaeus, 1758 sampled in Queensland and in New South Wales. The genus Lernanthropus is the most species rich and we report the presence of 20 nominal species on Australian marine fishes. This total includes six new species: L. alepicolus sp. nov. from Alepes apercna Grant, 1987, L. elegans sp. nov. from Atractoscion aequidens (Cuvier, 1830), L. gnathanodontus sp. nov. from Gnathanodon speciosus (Forsskål, 1775), L. paracruciatus sp. nov. from Protonibea diacanthus (Lacepède, 1802), L. pemphericola sp. nov. from Pempheris compressa (White, 1790), and L. selenotoca sp. nov. from Selenotoca multifasciata (Richardson, 1846). In addition, we report the presence of another four species in Australian waters for the first time: L. abitocephalus Tripathi, 1962, L. cadenati Delamare Deboutteville & Nuñes-Ruivo, 1954, L. microlamini Hewitt, 1968, and L. pomadasysis Rangnekar & Murti, 1961. After reexamination of the types of L. paenulatus Wilson, 1922 held in the USNM, we relegate this species to subjective synonymy with L. seriolii Shishido, 1898. Previous records of L. paenulatus from Australian Seriola species should be reassigned to L. seriolii. Lernanthropus ecclesi Kensley & Grindley, 1973 is recognized as a junior subjective synonym of L. micropterygis Richiardi, 1884, and L. delamarei Marques, 1960, which is based on the male only, is tentatively considered to be a junior subjective synonym of L. micropterygis. Males are described for the first time for three species; L. breviculus Kabata, 1979, L. microlamini and L. mollis Kabata, 1979. A member of the genus Mitrapus Song & Chen, 1976, M. oblongus (Pillai, 1964), is reported from Australia for the first time, on Herklotsichthys castelnaui (Ogilby, 1897) caught off Queensland and New South Wales. Finally, two species of Sagum were previously known from Australia and here we add three more. Two of the newly reported species were originally described as species of Lernanthropus but we formally transfer them here to Sagum as S. lativentris (Heller, 1865) n. comb. and S. sanguineus (Song, in Song & Chen, 1976) n. comb. The males of S. lativentris and S. vespertilio Kabata, 1979 are described for the first time. A key to the females of the 31 species of lernanthropids found in Australian waters is provided.

Larval assemblages over the abyssal plain in the Pacific are highly diverse and spatially patchy

Abyssal plains are among the most biodiverse yet least explored marine ecosystems on our planet, and they are increasingly threatened by human impacts, including future deep seafloor mining. Recovery of abyssal populations from the impacts of polymetallic nodule mining will be partially determined by the availability and dispersal of pelagic larvae leading to benthic recolonization of disturbed areas of the seafloor. Here we use a tree-of-life (TOL) metabarcoding approach to investigate the species richness, diversity, and spatial variability of the larval assemblage at mesoscales across the abyssal seafloor in two mining-claim areas in the eastern Clarion Clipperton Fracture Zone (CCZ; abyssal Pacific). Our approach revealed a previously unknown taxonomic richness within the meroplankton assemblage, detecting larvae from 12 phyla, 23 Classes, 46 Orders, and 65 Families, including a number of taxa not previously reported at abyssal depths or within the Pacific Ocean. A novel suite of parasitic copepods and worms were sampled, from families that are known to associate with other benthic invertebrates or demersal fishes as hosts. Larval assemblages were patchily distributed at the mesoscale, with little similarity in OTUs detected among deployments even within the same 30 × 30 km study area. Our results provide baseline observations on larval diversity prior to polymetallic nodule mining in this region, and emphasize our overwhelming lack of knowledge regarding larvae of the benthic boundary layer in abyssal plain ecosystems.