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Planktonic Phases of Symbiotic Copepods: a Review
Full text linkIn symbiotic copepods, most naupliar stages are typically planktonic, playing a primary role in dispersal, while the first copepodid usually represents the infective stage. Later copepodid stages, including adults, are associated with host organisms. Many symbiotic copepods have abbreviated life cycles, with a reduced number of naupliar stages and two different feeding habits. These patterns are presumably related to distinct life cycles strategies. Exceptional cases are exemplified by members of the Monstrillidae and Thaumatopsyllidae, both of which are protelean parasites, with infective nauplii and non-feeding planktonic adults. In the Caligidae, the life cycle follows a generalized pattern, but adults of many species like Caligus undulatus seem to exhibit a dual mode of life involving host switching. Adults leaving the first host become temporarily planktonic before attaching to the final host. This dual mode of life is also found in adults of the Ergasilidae. Abbreviation of the planktonic phase is characteristic for some symbiotic taxa, thus suggesting that they have evolved to become highly efficient in locating and infecting new hosts without needing long-distance larval dispersal. The life cycle of copepods associated with zooplankters is also briefly reviewed. Zooplankters are clearly less used as hosts by copepods than benthic invertebrates. It is likely that symbiotic copepods dynamically utilize planktonic phases in their life cycle, thus maintaining the balance between dispersal, host location, reproduction, and predator-avoidance strategies
Phylogenetic Study of Dioecious and Parthenogenetic Populations of Canthocamptus staphylinus (Crustacea, Copepoda, Harpacticoida)
Full text linkThe phylogenetic relationships of four dioecious populations and one parthenogenetic population of the harpacticoid Canthocamptus staphylinus Jurine were studied. Analysis of the mtCOI gene revealed two main clades as a phylogenetic tree and a network of haplotypes: a clade with Fennoscandian populations in Lake Pääjärvi (Finland) and Lake Vänern (Sweden), and a second clade with populations in Lake Võrtsjärv (Estonia), Orlov Pond in Saint Petersburg (Russia), and the type locality of the species in Lake Geneva (Switzerland).The parthenogenetic population of C. staphylinus showed the smallest nucleotide and haplotype polymorphisms and could have evolved as a reaction to the changing environmental conditions following the Last Glacial Maximum, 20K YBP
Spots on Sides of Giant Sea Bass (Stereolepis gigas Ayres, 1859) are Likely Unique to Each Individual
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Mortality of federally endangered fishes induced by artificial breaching of the Santa Clara River lagoon, Ventura County, southern California
Full text linkFishes of southern California coastal streams and associated coastal lagoons live with a Mediterranean-style hydrological cycle. Winter rains open the lagoons to the ocean; subsequent dry season low flows and changes in sandy beach dynamics closes them for most of the year. Artificial breaching of barrier sand berms can disrupt fish populations and cause mortality. Such breaches have been rarely observed and then only after some time has passed. An artificial breaching at the mouth of the Santa Clara River, Ventura County, CA coincided with an extreme low tide on 17 September 2010. We observed the mortality of thousands of both native and non-native fishes and invasive frogs; including at least thousands of the federally endangered Tidewater Goby (Eucyclogobius newberryi) and seven smolts of the federally endangered southern Steelhead (Oncorhynchus mykiss). Despite the many anthropogenic, faunal, and non-faunally related reasons for breaching, our observations confirm such actions can be detrimental to conservation and recovery of threatened and endangered species as well as to other fauna and flora dependent on such habitats
