Scattered CaSO4-crystallites on needle surfaces after simulated acid rain as an indicator of nutrient leaching

Two acid rain experiments were conducted, one at Oulu using transplanted seedlings of Picea abies and Pinus sylvestris, and the other with adult pines at Kevo where test plots were designated in a natural mixed stand of Pinus sylvestris and Betula tortuosa. The acid solution was made by adding H₂SO₄ and HNO3 (vol:vol 2:1, pH adjusted to 3 and 4) to clean water.The Oulu experiment was carried out from 1986 to 1989, and Kevo from 1985 to 1989. No visible injuries related directly to the acid rain treatment could be observed after 3 yr of the experiments, but microscopic examination revealed significant changes in the structure and morphology of the needles. The conifer seedlings treated at pH 3 had significant amounts of scattered CaSO₄ crystallites and characteristic piles and bows on the needle surfaces, as detected with EDS. The number of CaSO₄ crystallites was higher on the surfaces of the spruce needles than those of the pine needles. The current needles had more crystallites than the previous year's needles.     

Peripheral α2-adrenoceptor antagonism affects the absorption of intramuscularly coadministered drugs

Objective

We determined the possible effects of a peripherally acting α₂-adrenoceptor antagonist, MK-467, on the absorption of intramuscularly (IM) coadministered medetomidine, butorphanol and midazolam.

Environmental DNA reveals the temporal and spatial extent of spawning migrations of European shad in a highly fragmented river basin

1. Artificial barriers on lowland rivers impede the spawning migrations of anadromous fishes, preventing access to historical spawning areas. In the cryptic European shads Alosa alosa and Alosa fallax (‘shad’ hereafter), this has resulted in population declines across their range. Conservation programmes aim to facilitate the passage of migrators over these barriers and so require baseline information on the spatial and temporal extent of current migrations.
2. Here, a shad-specific environmental DNA (eDNA) assay was used to quantify the spatial extent of shad spawning migrations in the River Severn basin, western England. This basin is characterized by the presence of multiple barriers in the lower catchment. In 2017, the eDNA assay was piloted in the River Teme, an important shad spawning tributary, and then applied in 2018 and 2019 across the lower Severn basin.
3. In all years, shad DNA was detected between mid-May and mid-June, with the maximum spatial extent of shad distribution being in early June when shad eDNA was detected upstream of weirs that were generally considered as impassable. In 2018, this included the detection of shad above the most upstream weir on the main River Severn that required individual fish to have passed six weirs.
4. Although barriers inhibit the spawning migrations of shad, this eDNA assay showed that some highly vagile individuals might be able to ascend these barriers and migrate considerable distances upstream. This suggests that efforts to increase the permeability of these barriers could result in relatively high numbers of migrating shad reaching upstream spawning areas. These results demonstrate that this eDNA assay could also be used across their range, to further quantify the spatial extent of their spawning, including in highly fragmented rivers and those where shad are believed to spawn only occasionally and are rarely observed.