Crecimiento en función de la densidad de poliquetos Diopatra aciculata

Effects of intraspecific density on growth of the tube-building polychaete Diopatra aciculata (Onuphidae) were examined over a three-month period within a marine worm aquaculture facility. Three polychaete densities (500, 1000 and 2000 worms/m2) were represented within triplicate 0.30 m2 boxes containing late juvenile D. aciculata, sandy sediment and recirculating seawater. Daily food ration per worm was held constant across all density levels. Total length, weight and number of segments were recorded for 20 polychaetes randomly removed from each of nine treatment boxes at weeks 1, 7 and 14. Mean daily growth was higher during weeks 1-7 than during weeks 7-14 for all growth variables at each density level. Polychaetes at the highest density level exhibited lower rates of growth and more broken and/or regenerating posterior segments than those at low density. High D. aciculata density was also associated with reduced dissolved oxygen concentrations and high polychaete mortality (20%). At medium polychaete density (1000/m2), D. aciculata exhibited low levels of apparent stress and high biomass return per unit area, both of which are important considerations in the aquaculture rearing of this species. We suggest that further studies focus on age- and size-related factors contributing to density effects on polychaete growth.Durante un período de más de tres meses se examinaron en instalaciones de acuicultura de gusanos marinos los efectos de la densidad interespecífica en el crecimiento del poliqueto tubícola Diopatra aciculata (Onuphidae). Se utilizaron tres niveles de densidad de poliquetos (aproximadamente 500, 1000 y 2000 gusanos/m2) en cajas experimentales de 0,30 m2 replicadas, conteniendo ejemplares juveniles avanzados de D. aciculata y sedimento arenoso, todo ello con recirculación de agua marina. La ración diaria de alimento por gusano se mantuvo constante en todos los niveles de densidad. Se registró la longitud total, el peso, y el número de segmentos en 20 poliquetos extraídos aleatoriamente para cada tratamiento durante las semanas 1, 7, y 14. Para cada uno de los niveles de densidad estudiados, el crecimiento diario promedio durante el período entre la semana 1 y la 7 fue mayor que durante el período entre la semana 7 y la 14 en todas las variables de crecimiento. Los poliquetos cultivados a mayores densidades poblacionales exhibieron menores tasas de crecimiento y un mayor número de segmentos posteriores fragmentados y/o regenerados que aquellos cultivados a menores densidades de población. Asimismo, la alta densidad de D. aciculata provocó menores concentraciones de oxígeno disuelto y un mayor índice de mortalidad de poliquetos (20% promedio). Al nivel medio de densidad de poliquetos (1000/m2), los ejemplares de D. aciculata presentaron un bajo nivel de estrés aparente y una elevada producción de biomasa por unidad de área, dos factores importantes en la crianza mediante técnicas de acuicultura de esta especie. Para posteriores estudios, se propone concentrarse en los efectos de la densidad en el comportamiento interactivo y en la competencia por el alimento. &nbsp

Lack of Support for the Association between GAD2 Polymorphisms and Severe Human Obesity

The demonstration of association between common genetic variants and chronic human diseases such as obesity could have profound implications for the prediction, prevention, and treatment of these conditions. Unequivocal proof of such an association, however, requires independent replication of initial positive findings. Recently, three (−243 A>G, +61450 C>A, and +83897 T>A) single nucleotide polymorphisms (SNPs) within glutamate decarboxylase 2 (GAD2) were found to be associated with class III obesity (body mass index > 40 kg/m(2)). The association was observed among 188 families (612 individuals) segregating the condition, and a case-control study of 575 cases and 646 lean controls. Functional data supporting a pathophysiological role for one of the SNPs (−243 A>G) were also presented. The gene GAD2 encodes the 65-kDa subunit of glutamic acid decarboxylase—GAD65. In the present study, we attempted to replicate this association in larger groups of individuals, and to extend the functional studies of the −243 A>G SNP. Among 2,359 individuals comprising 693 German nuclear families with severe, early-onset obesity, we found no evidence for a relationship between the three GAD2 SNPs and obesity, whether SNPs were studied individually or as haplotypes. In two independent case-control studies (a total of 680 class III obesity cases and 1,186 lean controls), there was no significant relationship between the −243 A>G SNP and obesity (OR = 0.99, 95% CI 0.83–1.18, p = 0.89) in the pooled sample. These negative findings were recapitulated in a meta-analysis, incorporating all published data for the association between the −243G allele and class III obesity, which yielded an OR of 1.11 (95% CI 0.90–1.36, p = 0.28) in a total sample of 1,252 class III obese cases and 1,800 lean controls. Moreover, analysis of common haplotypes encompassing the GAD2 locus revealed no association with severe obesity in families with the condition. We also obtained functional data for the −243 A>G SNP that does not support a pathophysiological role for this variant in obesity. Potential confounding variables in association studies involving common variants and complex diseases (low power to detect modest genetic effects, overinterpretation of marginal data, population stratification, and biological plausibility) are also discussed in the context of GAD2 and severe obesity

Density-dependent growth of the polychaete Diopatra aciculata

Effects of intraspecific density on growth of the tube-building polychaete Diopatra aciculata (Onuphidae) were examined over a three-month period within a marine worm aquaculture facility. Three polychaete densities (500, 1000 and 2000 worms/m2) were represented within triplicate 0.30 m2 boxes containing late juvenile D. aciculata, sandy sediment and recirculating seawater. Daily food ration per worm was held constant across all density levels. Total length, weight and number of segments were recorded for 20 polychaetes randomly removed from each of nine treatment boxes at weeks 1, 7 and 14. Mean daily growth was higher during weeks 1-7 than during weeks 7-14 for all growth variables at each density level. Polychaetes at the highest density level exhibited lower rates of growth and more broken and/or regenerating posterior segments than those at low density. High D. aciculata density was also associated with reduced dissolved oxygen concentrations and high polychaete mortality (20%). At medium polychaete density (1000/m2), D. aciculata exhibited low levels of apparent stress and high biomass return per unit area, both of which are important considerations in the aquaculture rearing of this species. We suggest that further studies focus on age- and size-related factors contributing to density effects on polychaete growth

Winter presence and temperature-related diel vertical migration of Striped Bass (Morone saxatilis) in an extreme high flow passage in the inner Bay of Fundy

During a multi-year fish tracking study, sub-adult and adult life stages of Shubenacadie River Striped Bass (Morone saxatilis) were detected throughout winter in the well-mixed, hypertidal waters of the Minas Passage, Bay of Fundy. Thirty-five percent of the Striped Bass tagged with Vemco V16 transmitters were detected by two Minas Passage receiver arrays. Transmissions were received on 82% of winter days (December to April) and by all receivers spanning the width of the passage. Tagged Striped Bass were detected largely within the top 20-40 m during the day. The extent of vertical migration to shallower waters at night showed a strong relationship with water temperature, however, there was no diel vertical movement pattern observed at water temperaturesThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Atlantic Sturgeon Spatial and Temporal Distribution in Minas Passage, Nova Scotia, Canada, a Region of Future Tidal Energy Extraction.

In the Bay of Fundy, Atlantic sturgeon from endangered and threatened populations in the USA and Canada migrate through Minas Passage to enter and leave Minas Basin. A total of 132 sub-adult and adult Atlantic sturgeon were tagged in Minas Basin during the summers of 2010-2014 using pressure measuring, uniquely coded, acoustic transmitters with a four or eight year life span. The aim of this study was to examine spatial and seasonal distribution of sturgeon in Minas Passage during 2010-2014 and test the hypothesis that, when present, Atlantic sturgeon were evenly distributed from north to south across Minas Passage. This information is important as tidal energy extraction using in-stream, hydrokinetic turbines is planned for only the northern portion of Minas Passage. Electronic tracking data from a total of 740 sturgeon days over four years demonstrated that Atlantic sturgeon used the southern portion of Minas Passage significantly more than the northern portion. Sturgeon moved through Minas Passage at depths mostly between 15 and 45 m (n = 10,116; mean = 31.47 m; SD = 14.88). Sturgeon mean swimming depth was not significantly related to bottom depth and in deeper regions they swam pelagically. Sturgeon predominately migrated inward through Minas Passage during spring, and outward during late summer-autumn. Sturgeon were not observed in Minas Passage during winter 2012-2013 when monitoring receivers were present. This information will enable the estimation of encounters of Atlantic sturgeon with in-stream hydrokinetic turbines

Summary of yearly detections of acoustically tagged Atlantic sturgeon that occurred in Minas Passage during 2010–2014 (n = 132).

<p>Summary of yearly detections of acoustically tagged Atlantic sturgeon that occurred in Minas Passage during 2010–2014 (n = 132).</p

Depth box plots (Line = median, box = 25 and 75% quartiles, whiskers = SD and dots = outliers) distribution for acoustically tagged Atlantic sturgeon recorded on the Ocean Tracking Network, Minas Passage Line, Minas Passage, Nova Scotia, Canada, totals for years 2010–2014.

<p>Depth box plots (Line = median, box = 25 and 75% quartiles, whiskers = SD and dots = outliers) distribution for acoustically tagged Atlantic sturgeon recorded on the Ocean Tracking Network, Minas Passage Line, Minas Passage, Nova Scotia, Canada, totals for years 2010–2014.</p

Results of OTN range test experiment calculated by Sanderson et al. (in preparation).

<p>Probability of detection of Atlantic sturgeon tagged with V16 acoustic tags (158 db, 75 sec average transmission interval) passing the OTN Minas Passage Line. Individual receivers are represented by blue lines with left hand side representing the south (first blue peak = receiver MPS012) and right side (last blue peak = receiver MPS001). Solid black line represents the probability of a tagged sturgeon being detected by at least one of the receivers. Probability of being detected by at least one receiver is nearly identical for the north and south sections of the line, with a small reduction in probability of detection in the middle.</p

Sturgeon day distribution for acoustically tagged Atlantic sturgeon recorded on the Ocean Tracking Network Minas Passage Line, Minas Passage, Nova Scotia, Canada, totals for years 2010–2014.

<p>Sturgeon day distribution for acoustically tagged Atlantic sturgeon recorded on the Ocean Tracking Network Minas Passage Line, Minas Passage, Nova Scotia, Canada, totals for years 2010–2014.</p

Summary of coded acoustic tag models used during Atlantic sturgeon tagging project in Minas Basin during the summers of 2010, 2011, 2012 and 2014 (n = 132).

<p>All models supplied by Vemco Inc., Halifax, NS, Canada.</p