Amitriptyline and imipramine inhibit the release of acetylcholine from parasympathetic nerve terminals in the rat iris

The electrically stimulated release of [3H]acetylcholine from the parasympathetic nerve terminals of the rat iris in vitro is increased in a dose-dependent manner by scopolamine but is decreased by the tricyclic antidepressants amitriptyline and imipramine. The increased release in the presence of scopolamine seems to be due to the blockade of a presynaptic muscarinic autoreceptor that, in the drug-free state, inhibits the release of acetylcholine. However, at drug concentrations that should have comparable antimuscarinic potency, the antidepressants inhibit the release of acetylcholine. This suggests that the anticholinergic side effects of the antidepressants may be due to the reduced release of acetylcholine from parasympathetic nerve terminals as well as a possible direct postsynaptic muscarinic receptor blocking action. Whatever the mechanism of this action, the antidepressants do not have the same effect as scopolamine at the presynaptic muscarinic autoreceptor in the rat iris. </jats:p

Patch dynamics driven by wave exposure in subtidal temperate seaweeds are exacerbated by warming oceans

Over the past decades, ocean temperatures have been steadily increasing and are projected to continue to do so, stressing many temperate marine organisms. Changing temperatures do not affect ecosystems in isolation, but interact with many other factors in shaping ecological communities. We investigated the changes over 2 decades in subtidal temperate seaweed communities over a wave exposure gradient in Western Australia, a global warming hotspot. We found higher diversity in the seaweed community and a higher proportion of biomass of species with a warm affinity (expressed as the tropicalization index: TI) over time. There was no decline in biomass of the dominant habitat-forming kelp Ecklonia radiata on low wave exposure reefs, while it was patchier and comprised a lower proportion of the total seaweed biomass on the medium and high wave exposure reefs. Furthermore, the presence of E. radiata was disproportionally associated with low abundances of seaweeds with warm affinity. The increasing patchiness of E. radiata likely provided a competitive release for other seaweeds, and the increase in abundance of Scytothalia dorycarpa likely provided a compensatory effect which resulted in a lower than expected TI. We found no indication of an ameliorating effect by wave exposure, and conclude that the patch dynamics driven by wave exposure are more likely exacerbated by increasing ocean temperatures on subtidal temperate reefs. If this continues, the reduction in E. radiata and increase in warm affiliated seaweeds will result in a more diverse seaweed community, but one with a lower standing biomass.</jats:p

Reef benthos of Seychelles - a field guide

Background During the 2019 First Descent: Seychelles Expedition, shallow and deep reef ecosystems of the Seychelles Outer Islands were studied by deploying a variety of underwater technologies to survey their benthic flora and fauna. Submersibles, remotely operated vehicles (ROVs) and SCUBA diving teams used stereo-video camera systems to record benthic communities during transect surveys conducted at 10 m, 30 m, 60 m, 120 m, 250 m and 350 m depths. In total, ~ 45 h of video footage was collected during benthic transect surveys, which was subsequently processed using annotation software in order to assess reef biodiversity and community composition. Here, we present a photographic guide for the visual identification of the marine macrophytes, corals, sponges and other common invertebrates that inhabit Seychelles’ reefs. It is hoped that the resulting guide will aid marine biologists, conservationists, managers, divers and naturalists with the coarse identification of organisms as seen in underwater footage or live in the field. New information A total of 184 morphotypes (= morphologically similar individuals) were identified belonging to Octocorallia (47), Porifera (35), Scleractinia (32), Asteroidea (19), Echinoidea (10), Actiniaria (9), Chlorophyta (8), Antipatharia (6), Hydrozoa (6), Holothuroidea (5), Mollusca (2), Rhodophyta (2), Tracheophyta (2), Annelida (1), Crinoidea (1), Ctenophora (1), Ochrophyta (1) and Zoantharia (1). Out of these, we identified one to phylum level, eight to class, 14 to order, 27 to family, 110 to genus and 24 to species. This represents the first attempt to catalogue the benthic diversity from shallow reefs and up to 350 m depth in Seychelles

Assessing coral reef biodiversity at the Glorieuses Islands Marine Park (Scattered Islands, SW Indian Ocean) with identification of priority zones for conservation

International audienc

Assessing coral reef biodiversity at the Glorieuses Islands Marine Park (Scattered Islands, SW Indian Ocean) with identification of priority zones for conservation

International audienc