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.