Historical biomonitoring of pollution trends in the North Pacific using archived samples from the Continuous Plankton Recorder Survey.

First started in 1931, the Continuous Plankton Recorder (CPR) Survey is the longest-running and most geographically extensive marine plankton sampling program in the world. This pilot study investigates the feasibility of biomonitoring the spatiotemporal trends of marine pollution using archived CPR samples from the North Pacific. We selected specimens collected from three different locations (British Columbia Shelf, Northern Gulf of Alaska, and Aleutian Shelf) in the North Pacific between 2002 and 2020. Comprehensive profiling of the plankton chemical exposome was conducted using liquid and gas chromatography coupled with tandem mass spectrometry (LC-MS/MS and GC-MS/MS). Our results show that phthalates, plasticizers, persistent organic pollutants (POPs), pesticides, pharmaceuticals, and personal care products were present in the plankton exposome, and that many of these pollutants have decreased in amount over the last two decades, which was most pronounced for tri-n-butyl phosphate. In addition, the plankton exposome differed significantly by regional human activities, with the most polluted samples coming from the nearshore area. Exposome-wide association analysis revealed that bioaccumulation of environmental pollutants was highly correlated with the biomass of different plankton taxa. Overall, this study demonstrates that exposomic analysis of archived samples from the CPR Survey is effective for long-term biomonitoring of the spatial and temporal trends of environmental pollutants in the marine environment.

Daytime variability in carotid baroreflex function in healthy human subjects.

Variability of blood pressure is limited by arterial baroreceptors, yet blood pressure still shows circadian changes. This study was undertaken to examine if the responses to the carotid baroreflex also change throughout the day. Responses of cardiac interval (RR), mean arterial pressure (MAP) and vascular resistance (VR) to carotid baroreflex stimulation and inhibition using pressures and suction applied to a neck chamber, were measured in 14 healthy, normotensive subjects. Studies were carried out at three hourly intervals between 09:00 and 21:00 hours. Stimulus-response curves were defined and the first differential of the curve was calculated to establish reflex sensitivity (maximal slope) and "operating" point (estimated carotid sinus pressure at point of maximum slope, OP). The principal findings are: (1) baroreflex sensitivity for the control of VR was at its highest at 09:00 (-3.4 +/- 0.6 units) compared to 12:00 (-1.9 +/- 0.4 units), 15:00 (-2.0 +/- 0.4 units) and 18:00 (-1.9 +/- 0.3 units) (all P < 0.05); (2) baroreflex OP for the control of MAP was at its lowest at 09:00 (P < 0.01); (3) baroreflex sensitivity for control of VR was significantly correlated with prevailing mean pressure (P < 0.05) and OP for the control of MAP (P < 0.02); (4) OP for control of RR, MAP and VR are all highly correlated to prevailing MAP (P < 0.0001). Our results suggest that baroreflex function varies throughout the day and this favors higher sensitivity and lower blood pressure in the mornings. We speculate that this may be of importance in long-term blood pressure regulation.