Acidification of Nova Scotia Lakes

Although water chemistry of precipitation and lakes in Nova Scotia is dominated by C1 from sea salt, correction for marine influence reveals that the dominant anion in acidified lakes is SO₄. Atmospheric deposition of non-marine SO₄ (SO₄) and NO₃- for the period 1977–1980 at 4 stations in southwest Nova Scotia averaged 47 meq SO₄ ^* m^?2 yr^?1 and 21 meq NI₃-m^?2 yr^?1 compared with 38 and 13 meq, respectively, for the average of 3 stations in the northeastern third of the province. Precipitation pH increased from 4.5 to 4.8 along the same axis. Almost 50% of the SO₄ deposition occurred when storms came from the southwest, indicating low pressure tracks which pass south of major Canadian sources of S. SO₄ ^* deposition in metropolitan Halifax (1982 bulk data) was 87 meq m^?2 yr^?1, due to local emissions of ca. 28 300 tonne S in the area, as well as LRTAP. Concurrent deposition of NO₃-N was 15 meq m^?2 yr^?1 (2.1 kg ha^?1 yr ^?1). Loadings from SO₄ deposition in the Halifax area amount to 42 kg ha^?1 yr^?1 and clearly exceed the federal guideline (M.O.I., 1983) of 20 kg ha^?1 yr^?1. Water chemistry of southwest, northeast, and Halifax area lakes show the same general SOI trends as observed for atmospheric deposition. In addition we find a positive relationship between SOI concentrations in the urban lakes and proximity to the center of the urban area.     

Evaluation of soybean germplasm conserved in NIAS genebank and development of mini core collections

Genetic variation and population structure among 1603 soybean accessions, consisted of 832 Japanese landraces, 109 old and 57 recent Japanese varieties, 341 landrace from 16 Asian countries and 264 wild soybean accessions, were characterized using 191 SNP markers. Although gene diversity of Japanese soybean germplasm was slight lower than that of exotic soybean germplasm, population differentiation and clustering analyses indicated clear genetic differentiation among Japanese cultivated soybeans, exotic cultivated soybeans and wild soybeans. Nine hundred ninety eight Japanese accessions were separated to a certain extent into groups corresponding to their agro-morphologic characteristics such as photosensitivity and seed characteristics rather than their geographical origin. Based on the assessment of the SNP markers and several agro-morphologic traits, accessions that retain gene diversity of the whole collection were selected to develop several soybean sets of different sizes using an heuristic approach; a minimum of 12 accessions can represent the observed gene diversity; a mini-core collection of 96 accession can represent a major proportion of both geographic origin and agro-morphologic trait variation. These selected sets of germplasm will provide an effective platform for enhancing soybean diversity studies and assist in finding novel traits for crop improvement.     

Widespread complex flow in the interior of the antarctic ice sheet

It has been suggested that as much as 90% of the discharge from the Antarctic Ice Sheet is drained through a small number of fast-moving ice streams and outlet glaciers fed by relatively stable and inactive catchment areas. Here, evidence obtained from balance velocity estimates suggests that each major drainage basin is fed by complex systems of tributaries that penetrate up to 1000 kilometers from the grounding line into the interior of the ice sheet. This finding has important consequences for the modeled or estimated dynamic response time of past and present ice sheets to climate forcing.     

Assessment of the socio-economic impacts associated with the arrival of apple snail (Pomacea canaliculata) in Mwea irrigation scheme,Kenya

Background

In Kenya, rice (Oryza sativa L.) is mainly produced under irrigation by small-scale farmers. Mwea irrigation scheme (MIS) in Kirinyaga County accounts for 80–88% of rice production. Here, rice is the main source of livelihood and a source of revenue generation for the county. However, a recently established invasive freshwater snail, Pomacea canaliculata (Lamarck) (family: Ampullariidae), a species of apple snail, presents a serious threat to rice production.

Results

Household surveys, focus group discussions and key informant interviews highlight apple snail as a serious problem in MIS. Households that observed at least a moderate level of infestation (>20% of cultivated area) experienced significant reductions in rice yield (~14%) and net rice income (~60%). Farmers reported increased use of chemical pesticides for management of apple snail. In addition, the cost of hired labor for physical removal of egg masses and snails is resulting in substantial negative effects on net income. Farmer age, area of land owned, responsibility for decision-making, receipt of extension advice, training, and membership of a farmer organization, were all statistically significant variables to explain farmers awareness of the need for area-wide apple snail management.

Conclusion

Strategies to limit the spread of apple snail are urgently needed. A Multi-Institutional Technical Team (MITT) has been established to spearhead management efforts and consolidate advice to farmers on how to manage apple snail. However, without action to mitigate spread, the consequences could be disastrous for rice production and food security in Kenya, and for other rice growing regions across Africa. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Foliar lifespan,phenology and seasonal dynamics of the invasive shrub Schinus terebinthifolia

Schinus terebinthifolia is a dioecious tree native to South America that has become an invasive weed in Florida, southern California, southern Arizona, Texas and Hawaii and has been naturalised in over 20 countries. Biological control is considered a viable long-term control option for S. terebinthifolia because release from natural enemies appears to be at least partly responsible for its success in Florida. We examined leaf phenology of S. terebinthifolia over a period of 15 months at five sites in central and southern Florida to provide information that may help in predicting the impacts of potential biocontrol agents for this weed. We documented leaf lifespan, the seasonality of leaf development and abscission and the survivorship of leaves that emerged during either spring, summer or autumn. Average leaf lifespan was >4.5 months at all sites, and leaf phenology followed the seasons closely. Although S. terebinthifolia possesses leaves throughout the year, leaf production was greatest from April to September, and most leaves were abscised in February and March. Spring- and summer-emerging leaves were also longer-lived than leaves produced during autumn. These results suggest that leaves of S. terebinthifolia would be most vulnerable to herbivory during the spring and summer months when newly growing leaf tissue is most plentiful. Biocontrol agents capable of damaging these tissues during spring/summer might be an effective means of controlling this invasive weed.