Results of zoobentos research in river Sotka, PINEZHSKY STATE RESERVE (Arkhangelsk region, Russia)

В статье рассмотрен качественный состав (видовое и таксономическое разнообразие) и количественные показатели (встречаемость, численность и биомасса) зообентоса р. Сотка в пространственном аспекте. Выявлены участки реки с минимальной и максимальной численностью и биомассой. Определены доминирующие группы донных животных по численности (личинки хирономид и малощетинковые черви) и биомассе (двукрылые, олигохеты и двустворчатые моллюски). На основе кластерного анализа (по видовому сходству) станции отбора бентосных проб объединены в 2 группы. Качество вод оценено как условно чистое - слабо загрязненное. Проведенные исследования зообентоса в уникальной реке на территории заповедника Пинежский будут использованы при ведении комплексного мониторинга качества вод и биотической части ее экосистемы (фито- и зоопланктон, зообентос, ихтиофауна), включая и приточную систему. The article considers the qualitative composition (species and taxonomic diversity) and quantitative indicators (occurrence, number and biomass) of zoobenthos of river Sotka in the spatial aspect. The sections of the river with the minimum and maximum abundance and biomass were identified. The dominant groups of benthic animals were determined by their numbers (chironomid larvae and small-bristle worms) and biomass (dipterans, oligochaetes and bivalve mollusks). Comparison of quantitative indicators in the annual aspect revealed a significant increase in biomass and relative stability of abundance over a 20-year period at the Filippovskoye site, as well as a decrease in numbers and biomass at the Moiseev Nos site. Based on cluster analysis (by species similarity), benthic sampling stations are combined into 2 groups. Water quality is assessed as conditionally pure, slightly polluted. Studies of zoobenthos in a unique river on the territory of the Pinezhsky reserve will be used to conduct a comprehensive monitoring of water quality and the biotic part of its ecosystem (phyto- and zooplankton, zoobenthos, ichthyofauna), including the inflow system.

Four new deep-water flabelligerid species from Pacific Costa Rica (Annelida, Sedentaria, Flabelligeridae)

The discovery of four undescribed flabelligerid species from deep-water in Pacific Costa Rica resulted in the restriction of Diplocirrus Haase, 1915. As currently understood, Diplocirrus and Pherusa Oken, 1807 are separated after their morphological pattern. The species belonging in Diplocirrus have two types of branchiae, poorly developed cephalic cages and multiarticulate neurochaetae, whereas Pherusa species have branchiae of one type, well-developed cephalic cages and completely anchylosed neurochaetae. Benthic sampling and processing usually damage cephalic cages and if chaetae are completely broken, one could regard specimens without them, when they actually have it, but lost after sieving. Sampling using Alvin deep-sea submarine at methane seeps off Costa Rica resulted in some well-preserved specimens, and some of them fall between these two genera because they have well developed cephalic cages, and multiarticulate neurochaetae. Saphobranchia Chamberlin, 1919, with Stylarioides longisetosa von Marenzeller, 1890, as type species, is herein reinstated for some species previously included in Diplocirrus, restricted. The transferred species, including three ones newly described herein, have branchiae of a single type, long cephalic cage and body chaetae, and neurochaetae basally anchylosed and medially and distally articulated; some species currently included in Diplocirrus described from Arctic or deep water sediments are transferred into it. A key to identify all species in Saphobranchia, and another key to identify species in the restricted Diplocirrus are also included. The three new Saphobranchia species are S. canela n. sp., S. ilys n. sp. and S. omorpha n. sp. The fourth species belongs in Lamispina Salazar-Vallejo, 2014, and it is herein described as L. polycerata n. sp. after the presence of some long papillae along anterior margin of chaetiger 1.

Lepidepecreoides stoddartae sp. nov. from the Falkland Islands (Amphipoda: Tryphosidae)

Lepidepecreoides stoddartae sp. nov. is described from the Falkland Islands. Previous reports of Lepidepecreoides K.H. Barnard, 1931 species usually include only a few specimens. The material examined is considered a large collection, with 12 individuals collected during benthic sampling by commercial oil and gas exploration. Lepidepecreoides stoddartae sp. nov. is the seventh species described in the genus, and can be presently defined by the gnathopod 1 propodus palm acute, pereopod 7 basis posterior margin serrations, and variation in the position, size and sculpturing of the projections on the pereopods 5 basis, pleonites and urosomite 1. An updated world key to the known species of Lepidepecreoides K.H. Barnard, 1931 is provided.

Estimating densities of larval Salmonflies (Pteronarcys californica) through multiple pass removal of post-emergent exuvia in Colorado rivers

Traditional methods of collecting and sorting benthic macroinvertebrate samples are useful for stream biomonitoring and ecological studies; however, these methods are time consuming, expensive, and require taxonomic expertise. Estimating larval densities through collection of post-emergent exuvia can be a practical and time efficient alternative. We evaluated the use of multiple pass depletion techniques of the post-emergent exuvia of Pteronarcys californica to estimate larval densities at ten sites in three Colorado rivers. Exuvia density was highly correlated with both final-instar larval density (R2 = 0.90) and total larval density (R2 = 0.88) and the multiple pass removal technique performed well. Exuvia surveys found P. californica at three low density sites where benthic sampling failed to detect it. At moderate and high density sites the exuvia surveys always produced lower density estimates than benthic surveys. Multiple pass depletion estimates of exuvia proved to be an accurate and efficient technique at estimating larval densities and provided an effective alternative for traditional benthic sampling when objectives are monitoring P. californica and detecting populations, especially at low density sites.

On some rare Oplophoridae (Caridea, Decapoda) from the South Mid-Atlantic Ridge

The Mid-Atlantic Ridge (MAR) divides the Atlantic Ocean longitudinally into two halves, each with a series of major basins delimited by secondary, more or less transverse ridges. Recent biological investigations in this area were carried out within the framework of the international project Mar-Eco (Patterns and Processes of the Ecosystems of the Mid-Atlantic Ridge). In 2009 (from October, 25 to November, 29) 12 benthic sampling events were conducted on the R/V Akademik Ioffe, during the first oceanographic cruise of South Atlantic Mar-Eco. As a result we report some rare Oplophoridae species collected during the cruise. This family includes 73 species occurring strictly on the meso- and bathypelagic zones of the oceans. Five Oplophoridae species were sampled: Acanthephyra acanthitelsonis Bate, 1888; A. quadrispinosa Kemp, 1939; Heterogenys monnioti Crosnier, 1987; Hymenodora glacialis (Buchholz, 1874) and Kemphyra corallina (A. Milne-Edwards, 1883). Among these, H. monnioti and K. corallina are considered extremely rare, both with very few records. Of the sampled species, only A. quadrispinosa and H. glacialis were previously recorded to southwestern Atlantic, so the Oplophoridae fauna of the South MAR seems more related with the fauna from the eastern Atlantic and Indian oceans.