Thermodynamic effects drive countergradient responses in the thermal performance of Littorina saxatilis across latitude.

Thermal performance curves (TPCs) provide a powerful framework to assess the evolution of thermal sensitivity in populations exposed to divergent selection regimes across latitude. However, there is a lack of consensus regarding the extent to which physiological adjustments that compensate for latitudinal temperature variation (metabolic cold adaptation; MCA) may alter the shape of TPCs, including potential repercussion on upper thermal limits. To address this, we compared TPCs for cardiac activity in latitudinally-separated populations of the intertidal periwinkle Littorina saxatilis. We applied a non-linear TPC modelling approach to explore how different metrics governing the shape of TPCs varied systematically in response to local adaptation and thermal acclimation. Both critical upper limits, and the temperatures at which cardiac performance was maximised, were higher in the northernmost (cold-adapted) population and displayed a countergradient latitudinal trend which was most pronounced following acclimation to low temperatures. We interpret this response as a knock-on consequence of increased standard metabolic rate in high latitude populations, indicating that physiological compensation associated with MCA may indirectly influence variation in upper thermal limits across latitude. Our study highlights the danger of assuming that variation in any one aspect of the TPC is adaptive without appropriate mechanistic and ecological context

Larval distribution of commercial fish species in waters around Ireland

In April 2000 a base line survey was conducted on the larval distribution of commercial fish species off the west, north and south coasts of Ireland. Ichthyoplankton samples and in situ CTD data were collected, whilst simultaneously capturing remote sensing images of chlorophyll and sea surface temperatures. The survey sampling area covered the Celtic Sea from the Irish south coast to 49 degree N, the western shelf including the Porcupine Bank and the northern shelf up to the Stanton Bank. The sample grid design was based on the international mackerel & horse mackerel egg survey with station spacings of 0.5 degree latitude and 0.5 degree longitude. Ichthyoplankton samples were collected with a Gulf III plankton sampler, which was deployed on oblique tows from the surface to within 5 metres of the bottom (200m max). A self-logging CTD sensor (Promonitor) was attached to the Gulf and recorded depth, temperature and salinity profiles for each deployment. Results from the Promonitor CTD showed that strong temperature and salinity gradients were encountered during the survey. Lowest temperatures coincided with lowest salinity in the North Channel of the Irish Sea while highest salinities and temperatures were found to the south west of Ireland.Thermal fronts were found in the eastern Celtic Sea and on the north west coast of Ireland.The AVHRR images showed a progressive increase in surface temperatures in the Celtic Sea and west of Ireland. Highest surface chlorophyll concentrations were associated with cooler less saline water in the Irish Sea and the coastal areas around Ireland. In the western Celtic Sea surface chlorophyll concentrations increased as the survey progressed to form a phytoplankton bloom towards the end of the survey. Larvae of interest showed distinct distribution patterns, with some species being confined to particular areas or spawning grounds while others were spread over the whole survey area. The survey identified two important larval hotspots: Cod larvae were concentrated in the eastern Celtic Sea, where other gadoid species such as haddock, whiting, pollack and saithe were also found in high numbers.This area is associated with the Celtic Sea front and shows increased primary productivity, which could present a favourable environment for successful larval survival. Stations in the southwest of Ireland sustained high concentrations of hake, megrim and mackerel larvae. The waters with high numbers of these three species stretched from shallow inshore stations to deeper ones along the continental shelf and were characterised by high temperatures and salinities. SeaWIFS satellite images suggest the formation of a phytoplankton bloom within this larval hotspot, which would provide the necessary resources for successful larval growth.Funder: Marine Institut

Factors predicting hospital length-of-stay and readmission after colorectal resection: a population-based study of elective and emergency admissions

<p>Abstract</p> <p>Background</p> <p>The impact of developments in colorectal cancer surgery on length-of-stay (LOS) and re-admission have not been well described. In a population-based analysis, we investigated predictors of LOS and emergency readmission after the initial surgery episode.</p> <p>Methods</p> <p>Incident colorectal cancers (ICD-O2: C18-C20), diagnosed 2002-2008, were identified from the National Cancer Registry Ireland, and linked to hospital in-patient episodes. For those who underwent colorectal resection, the associated hospital episode was identified. Factors predicting longer LOS (upper-quartile, > 24 days) for elective and emergency admissions separately, and whether LOS predicted emergency readmission within 28 days of discharge, were investigated using logistic regression.</p> <p>Results</p> <p>8197 patients underwent resection, 63% (n = 5133) elective and 37% (n = 3063) emergency admissions. Median LOS was 14 days (inter-quartile range (IQR) = 11-20) for elective and 21 (15-33) for emergency admissions. For both emergency and elective admissions, likelihood of longer LOS was significantly higher in patients who were older, had co-morbidities and were unmarried; it was reduced for private patients. For emergency patients only the likelihood of longer LOS was lower for patients admitted to higher-volume hospitals. Longer LOS was associated with increased risk of emergency readmission.</p> <p>Conclusions</p> <p>One quarter of patients stay in hospital for at least 25 days following colorectal resection. Over one third of resected patients are emergency admissions and these have a significantly longer median LOS. Patient- and health service-related factors were associated with prolonged LOS. Longer LOS was associated with increased risk of emergency readmission. The cost implications of these findings are significant.</p