Distribution of Stream Macroalgae in Four High Arctic Drainage Basins

Eighty-three stream reaches were sampled from four drainage basins in the central portions of Axel Heiberg and Ellesmere Islands. The stream included small snowmelt tributaries, those flowing through wetlands, pond outflows, glacial meltwaters, and large trunk rivers, some of which had become braided in their lower portions. Larger channels tended to be quite turbid, and macroscopic algae were negligible in these reaches because they lack adequate light and hard substrata for attachment. The overall stream macroalgal flora was relatively small (15 species) compared to that of other regions of the North American tundra. Cyanobacteria and Chlorophyta accounted for all but one species. The most widespread species was the colonial cyanobacterium, Nostoc commune. Only Scytonema mirabile (Cyanophyta) was a new addition to the stream macroalgal flora of arctic North America. The numbers of species per stream reach ranged from 0 to 5, with a mean of 1.3. The amount of stream bottom covered by macroalgae was 0 to 75%, with an average of ca. 5%. Both species number and percent cover per reach are relatively low.On a procédé à des échantillonnages de 83 tronçons de cours d'eau situés dans quatre bassins de drainage au centre de l'île Axel Heiberg et de l'île d'Ellesmere. Les cours d'eau comprenaient de petits affluents alimentés par la fusion nivale, ceux qui traversaient des terres humides, des émissaires d'étangs, des eaux de fonte glaciaires et d'importants cours d'eau principaux, dont certains étaient devenus anastomosés en aval. Les chenaux larges avaient tendance à être relativement troubles et on ne trouvait que peu d'algues macroscopiques dans ces tronçons en raison du manque de lumière adéquat et des substrats de soutien. La flore macroalgale globale des cours d'eau était assez réduite (15 espèces) par rapport à celle d'autres régions de la toundra nord-américaine. Toutes les espèces sauf une appartenaient aux cyanobactéries et aux chlorophycées. L'espèce la plus répandue était la cyanobactérie coloniale, Nostoc commune. Seule Scytonema mirabile (cyanophycée) était une nouveauté dans la flore macroalgale de l'Arctique nord-américain. Le nombre d'espèces par cours d'eau allait de 0 à 5, avec une moyenne de 1,3. De 0 à 75 p. cent de la superficie du fond des cours d'eau était couverte par les macroalgues, avec une moyenne d'environ 5 p. cent. Le nombre d'espèces comme le pourcentage de leur couverture par tronçon étaient relativement bas

Parasites of non-native freshwater fishes introduced into england and wales suggest enemy release and parasite acquisition

When non-native species are introduced into a new range, their parasites can also be introduced, with these potentially spilling-over into native hosts. However, in general, evidence suggests that a high proportion of their native parasites are lost during introduction and infections by some new parasites from the native range might occur, potentially resulting in parasite spill-back to native species. These processes were investigated here using parasite surveys and literature review on seven non-native freshwater fishes introduced into England and Wales. Comparison of the mean numbers of parasite species and genera per population for each fish species England andWaleswith their native ranges revealed\9 % of the native parasite fauna were present in their populations in England and Wales. There was no evidence suggesting these introduced parasites had spilled over into sympatric native fishes. The non-native fishes did acquire parasites following their introduction, providing potential for parasite spill-back to sympatric fishes, and resulted in non-significant differences in overall mean numbers of parasites per populations between the two ranges. Through this acquisition, the non-native fishes also had mean numbers of parasite species and genera per population that were not significantly different to sympatric native fishes. Thus, the non-native fishes in England and Wales showed evidence of enemy release, acquired new parasites following introduction providing potential for spill-back, but showed no evidence of parasite spill-over

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Stream Macroalgae of the Fiji Islands: A Preliminary Study

Twenty-seven stream segments sampled in August 1994 on the three largest Fiji Islands ranged considerably in channel size (maximum width 1-20 m, maximum depth 20->100 cm) and mean current velocity (1-118 cm sec-1 ). Water temperatures tended to be warm (23-30°C), pH was neutral to slightly alkaline (7.2-8.6), and specific conductance was quite variable (40-510 mS cm-1 ). Mean number of species per stream segment was 2.6 and ranged from one to five. In the 71 populations of stream macroa1gae sampled, only 15 species were identified: seven Cyanophyta, six Chlorophyta, and two Rhodophyta. All of these species represent new records for the freshwater algal flora of Fiji. Macroalgal cover ranged from 76% (mean ca. 36%) of the stream bottom and was positively correlated to maximum depth and mean current velocity. The most widespread species that occurred on all three islands were the cyanophytes Phormidium retzii (C.Ag.) Gom. and P. subfuscum Klitz. and the chlorophyte Spirogyra sp. 2 (17, 9, and 19 segments, respectively). Morphological forms included nine mats, three free filaments, and one each of gelatinous colonies, crusts, and tufts. Eleven of the 15 species were in the vegetative state. There were nine species of stream macroalgae on Vitu Levu and eight each on Vanua Levu and Taveuni. The Sorenson's similarity index was highest for the last two islands and lowest for the first two islands

Stream Macroalgae of the Hawaiian Islands: a Preliminary Study

Thirty-four stream segments sampled on the four largest Hawaiian Islands had water temperatures ranging from 20 to 27°C, neutral to alkaline pH (6.7-8.0), and relatively low ion content (30-360 uS cm-l). Mean species number per stream segment was 3.4 and ranged from one to seven. Macroalgal cover varied considerably from 76% (mean, ca. 27%) of the stream bed. In the 114 populations of stream macroalgae collected, 34 species were found: 16 Chlorophyta, 11 Cyanophyta, five Rhodophyta, and two Chrysophyta, of which 25 are new records for Hawai'i; the morphological forms were 16 mats, eight free filaments, seven tufts, one colony, one crust, and one gelatinous filament. The most widespread species was the cyanophyte Phormidium retzii (C.Ag.) Gom., occurring in 18 stream segments. In terms of reproductive status of the populations sampled, 75% were vegetative, 25% were asexual, and < 1% was sexual. Only one new species was collected, the rhodophyte Batrachospermum spermatiophorum, belonging to the Section Contorta and having unique colorless spermatiophores and large whorls, carposporophytes, and carposporangia