\u3ci\u3eAquastella gen. nov.\u3c/i\u3e: A new genus of saprolegniaceous oomycete rotifer parasites related to \u3ci\u3eAphanomyces\u3c/i\u3e, with unique sporangial outgrowths

The oomycete genus Aquastella is described to accommodate two new species of parasites of rotifers observed in Brooktrout Lake, New York State, USA. Three rotifer species – Keratella taurocephala,Polyarthra vulgaris, and Ploesoma truncatum – were infected, and this is the first report of oomycete infection in these species. Aquastella attenuata was specific to K. taurocephala and Aquastella aciculariswas specific to P. vulgaris and P. truncatum. The occurrence of infections correlated with peak host population densities and rotifers were infected in the upper layers of the water column. Sequencing of 18S rRNA and phylogenetic analysis of both species placed them within the order Saprolegniales, in a clade closely related to Aphanomyces. The Aquastella species were morphologically distinct from other rotifer parasites as the developing sporangia penetrated out through the host body following its death to produce unique tapered outgrowths. Aquastella attenuata produced long, narrow, tapering, finger-like outgrowths, whilst A. acicularis produced shorter, spike-like outgrowths. We hypothesize that the outgrowths serve to deter predation and slow descent in the water column. Spore cleavage was intrasporangial with spore release through exit tubes. Aquastella attenuata produced primary zoospores, whereas A. acicularisreleased spherical primary aplanospores, more typical of other genera in the Aphanomyces clade

Potential loss and rehabilitation of stream longitudinal connectivity: fish populations in urban streams with culverts

Riverine connectivity is important to the persistence of fish communities, but culverts may impede fish movements to varying degrees and in both directions. Baffles can be installed in culverts to mitigate upstream connectivity loss; however, evaluation of their effectiveness is limited. To examine the potential impacts of culverts and their potential rehabilitation with baffles, we sampled fish populations in 26 streams that contained either (i) nonbaffled culverts or (ii) baffled culverts or (iii) lacked culverts (reference streams) in Metro Vancouver, British Columbia, Canada. Using mixed effects models, we compared fish responses across these three stream types to infer effects at the whole-stream scale (i.e., over both upstream and downstream positions equally), the within-stream scale (i.e., upstream versus downstream of culverts), and the interaction of scales. Densities (n·m−2) of coastrange sculpin (Cottus aleuticus) and prickly sculpin (Cottus asper) were significantly lower in nonbaffled and baffled stream types than in reference stream types, while densities of cutthroat trout (Oncorhynchus clarkii) and rainbow trout (Oncorhynchus mykiss) were significantly lower in reference stream types, indicating whole-stream differences. Using multivariate statistics, we similarly found that fish community compositions were significantly different across stream types. For our various fish responses, we found no interaction between stream type and upstream or downstream position. Further, we found reaches directly downstream of baffled culverts had greater fish biomass and that overall species richness increased with age of baffles. These data suggest that culverts may drive changes in fish populations at whole-stream scales, and restoration of these effects with baffles may take decades. </jats:p

Steelhead Ration Schedule

This file shows the sequence of high and low ration treatments for each tank and the date at which changes in ration occurred

Data from: Separating intrinsic and environmental contributions to growth and their population consequences

Among-individual heterogeneity in growth is a commonly observed phenomenon that has clear consequences for population and community dynamics yet has proved difficult to quantify in practice. In particular, observed among-individual variation in growth can be difficult to link to any given mechanism. Here, we develop a Bayesian state-space framework for modeling growth that bridges the complexity of bioenergetic models and the statistical simplicity of phenomenological growth models. The model allows for intrinsic individual variation in traits, a shared environment, process stochasticity, and measurement error. We apply the model to two populations of steelhead trout (Oncorhynchus mykiss) grown under common but temporally varying food conditions. Models allowing for individual variation match available data better than models that assume a single shared trait for all individuals. Estimated individual variation translated into a roughly twofold range in realized growth rates within populations. Comparisons between populations showed strong differences in trait means, trait variability, and responses to a shared environment. Together, individual- and population-level variation have substantial implications for variation in size and growth rates among and within populations. State-dependent life-history models predict that this variation can lead to differences in individual life-history expression, lifetime reproductive output, and population life-history diversity

Steelhead Size Data

This file contains length and weight time series for individual steelhead trout raised in tanks in Santa Cruz California during 2006. Individual fish were measured on a series of days starting in spring 2006 to spring 2007. The fish were derived from two hatcheries (Scott Creek Hatchery and Coleman National Fish Hatchery, denoted as "Scott" and "Coleman" respectively) and raised in set of tanks. The tank number in which each fish grew is noted in the file. The fish were fed two rations levels (high or low) and the ration associated with each time is noted in the column labeled "Ration." The sequence of feeding treatments determine the "Treatment" column which has four levels (1,2,3, or 4). See the publication for more detailed information

Aquastella gen. nov.: A new genus of saprolegniaceous oomycete rotifer parasites related to Aphanomyces, with unique sporangial outgrowths

International audienceThe oomycete genus Aquastella is described to accommodate two new species of parasites of rotifers observed in Brooktrout Lake, New York State, USA. Three rotifer species - Keratella taurocephala, Polyarthra vulgaris, and Ploesoma truncatum - were infected, and this is the first report of oomycete infection in these species. Aquastella attenuata was specific to K. taurocephala and Aquastella acicularis was specific to P. vulgaris and P. truncatum. The occurrence of infections correlated with peak host population densities and rotifers were infected in the upper layers of the water column. Sequencing of 18S rRNA and phylogenetic analysis of both species placed them within the order Saprolegniales, in a clade closely related to Aphanomyces. The Aquastella species were morphologically distinct from other rotifer parasites as the developing sporangia penetrated out through the host body following its death to produce unique tapered outgrowths. Aquastella attenuata produced long, narrow, tapering, finger-like outgrowths, whilst A. acicularis produced shorter, spike-like outgrowths. We hypothesize that the outgrowths serve to deter predation and slow descent in the water column. Spore cleavage was intrasporangial with spore release through exit tubes. Aquastella attenuata produced primary zoospores, whereas A. acicularis released spherical primary aplanospores, more typical of other genera in the Aphanomyces clade. (C) 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved