With the ongoing worldwide destruction of freshwater habitats, data on biological indicators are necessary to assess their health status and develop appropriate management plans and preserve their biodiversity. Odonata are very effective in that regard. Dragonflies were surveyed during 14 months in five habitats in the South Region of Cameroon. A total of 3595 individuals representing 101 species were recorded. The most abundant species was Pseudagrion kibalense, representing 12 % of all the individuals. On average, the species richness, the Shannon’s index and the evenness varied significantly among the habitats. The highest species richness was found in the open stream (mean 24.07 ± standard deviation (S.D.) = 5.01) and the lowest in the forest swamp (11.21 ± S.D. 2.15). The highest Shannon index was reported in the open stream (2.75 ± S.D. 0.21) and the lowest in the forest stream (1.99 ± S.D. 0.44). The results of the indicator value (IndVal) identified 37 species as indicators of habitat types. The open stream had the highest number of indicator species, with 24 species, followed by the forest stream with seven, the forest swamp with five and the bamboo stream with one. No indicator species was found in the swampy canal. Chlorocypha cyanifrons, Copera rufipes and Agriocnemis forcipata were identified as the strongest ecological indicator species of the forest stream, the forest swamp and the open stream, respectively. The current data provides an insight into the ecology of odonates in tropical Africa and help to understand how the habitats can influence community composition.

The study aimed to characterize the species composition and compare helminth populations and communities in samples of helminths collected from marsh frogs in 3 localities in the city of Kyiv. Twenty helminth species were recorded in total, of which 8 were found in all 3 localities: the nematodes Cosmocerca ornata and Icosiella neglecta, and the trematodes Diplodiscus subclavatus, Haematoloechus asper, Opisthioglyphe ranae, Pleurogenes claviger, Pleurogenoides medians and Prosotocus confusus. In helminth infracommunities, species richness and abundance were the highest in frogs from Olzhyn Island (median 7 and 98, respectively). Helminth species richness was the lowest in the infracommunities from Lake Tiahle (median 4), while the abundance was the lowest in the infracommunities from Lake Telbin (median 51.5). From 3 to 4 species predominated in separate helminth component communities based on their high prevalence and abundance in the studied samples: D. subclavatus, I. neglecta, P. medians and P. confusus in Lake Telbin; Codonocephalus urniger, I. neglecta, O. ranae and P. confusus in Lake Tiahle; C. urniger, O. ranae and Tylodelphys excavata in Olzhyn Island. According to our observations, intense urbanization of Lake Telbin affects rather the abundance than the species richness in helminth communities of the marsh frog. On the other hand, the relatively low abundance of helminths in the infrapopulations from Lake Telbin resulted in comparatively higher diversity indices for the helminth component community in this locality. Moderate urbanization, on the contrary, results in the strong predominance of some helminth species and low values of the diversity indices.

Interest in cover crops is increasing but information is limited on integrating them into crop rotations especially in the relatively short growing season on the northern Great Plains. A 3-yr research project, initiated in 2009 near Mandan, North Dakota, USA, evaluated (1) what impact cover crops may have on subsequent cash crops yields and (2) whether cover crop mixtures are more productive and provide additional benefits compared to cover crop monocultures. The study evaluated 18 different cover crop monocultures and mixtures that were seeded in August following dry pea (Pisum sativum L.). The following year, spring wheat (Triticum aestivum L.), corn (Zea mays L.), soybean (Glycine max L.) and field pea were seeded into the different cover crop treatments and a non-treated control. A lack of timely precipitation in 2009 resulted in a low cover crop yield of 17 g m2 compared to 100 and 77 g m2 in 2008 and 2010, respectively. Subsequent cash crop yield was not affected by late-seeded cover crops. Cool-season cover crop monocultures were more productive than warm-season monocultures and some mixtures in 2008 and 2010. Relative yield total did not differ from one in any cover crop mixture suggesting that overyielding did not occur. Species selection rather than species diversity was the most important contributor to cover crop yield. Cover crops can be grown following short-season cash crops in the northern Great Plains, but precipitation timing and species selection are critical.

The biodiversity and composition of endoparasites in fish obtained from the Antarctic and subantarctic zones are compared in this study. Several fish were collected in the summer from Antarctica (King George Island) and the Southern Pacific coast (Strait of Magellan and Almirante Montt Gulf). This database was complemented with published information on fish endoparasite communities from both zones, with specimens of fish sample size n ≥ 15. Thus, 31 fish species were analysed in this study, which altogether had 79 parasite species. Diversity indices were calculated for the parasite community of each fish species. Then they were compared between the Antarctic and subantarctic zones. Parasite species composition and host specificity (as the number of fish species used by a parasite species) were also analysed and compared between zones. The diversity indices and the abundance of parasites were significantly higher in the Antarctic than the subantarctic fish. Few parasite species (7.6%) were shared between fish from both zones, showing significant differences in parasite composition. Antarctic parasites were less host-specific than subantarctic parasites, which allowed the coexistence of several parasite species in the fish. The high parasite abundance in Antarctic fish could trigger sympatric speciation in certain parasitic lineages or the exploitation of new resources, resulting in more parasite species than those in subantarctic environments. The high abundance of Antarctic parasites implies different methods and rates of transmission than those of subantarctic parasites. In addition, more alternative fish hosts were used by the Antarctic than subantarctic parasites. This altogether indicates that host–parasite interaction dynamics significantly differ between the Antarctic and subantarctic systems.

Studies of species assemblages and community structure are of vital importance in the deep-sea realm. Data for the present study were collected during the research expedition of FORV ‘Sagar Sampada’ in the latitude 8.02°N and 11.58°N, longitude 74.16°E and 78.35°E. High Speed Demersal Trawl – Crustacean Version (HSDT-CV) was used for the operations at a depth of 200 and 1000 m. The total catch came to 2148.35 kg from 10 stations. An analysis of the catch composition was made. Total catch was dominated by Priacanthus hamrur (27.66%) followed by Neoepinnula orientalis (15.57%), Psenopsis cyanea (10.05%), Glyptophidium oceanium (3.55%), Lamprogrammus niger (3.17%), Narcine timlei (3.08%), Lamprogrammus sp. (2.6%), Pterigotrygla hemisticta (2.17%). About 76 species recorded from 22 orders were identified. The diversity indices, Cluster analysis, k-dominance plot were analysed using PRIMER v6 software. The diversity indices including Margalef richness index (d), Shanon index (log e2), Pielou's evenness index (J′) and Simpson diversity index (1 − λ) were calculated. Diversity indices were compared with the previous studies in the same area, and this can be a reference point for future studies.