DOI: 10.7280/d1m39b
title: Data from: Accounting for variation in temperature and oxygen availability when quantifying marine ecosystem metabolism

description: Given human modification of Earth’s ecosystems, it is essential to
 understand how these changes are influencing ecosystem functioning,
 including net and gross community production and community respiration.
 These responses are often estimated by measuring oxygen production in the
 light (net community production) and consumption in the dark (community
 respiration). These values can then be combined to estimate gross
 community production. However, the method used to create “dark” conditions
 – either experimental darkening during the day or conducting measurements
 at night – could result in different estimates of respiration and
 production. These data were used to test this prediction and
 include measurements of oxygen concentrations under daytime
 “ambient” light conditions, in darkened tide pools during the day, and
 during nighttime low tides. We made measurements every 1-3 months over one
 year in southeastern Alaska. We found that daytime respiration rates were
 substantially higher than those measured at night. These differences were
 associated with higher temperature and oxygen levels during the day and
 led to major differences in estimates of gross community production
 calculated using daytime versus nighttime respiration measurements. Our
 results highlight the need to measure respiration rates during both day
 and night to account for effects of temperature and oxygen.
description: During each sampling event, two complementary sets of data were
 collected to evaluate changes in O<sub>2</sub> concentrations
 in the pools. The first consisted of daytime and nighttime (Day-Night)
 sampling, where pools were left uncovered and light varied naturally on a
 diel cycle. During one daytime and one nighttime low tide event, we took
 in-situ<i> </i>measurements and collected water samples.
 Initial readings of O<sub>2</sub> (DSS optical DO meter, YSI,
 Inc., Yellow Springs, Ohio, USA), temperature (YSI DSS), and light (MQ 210
 Underwater Quantum Meter, Apogee Instruments, Logan, Utah, USA) were taken
 in each pool as soon as the pool was isolated by the receding tide. After
 a minimum of 1 hr (median = 1.5 hr, max = 3.5 hr), pools were resampled,
 and a second set of O<sub>2</sub>, temperature, and light
 measurements were taken. Daytime measurements were taken on days when
 irradiance levels were high enough to saturate photosynthetic rates of the
 most widespread and abundant seaweed species in the tide pools,
 <i>Neorhodomela oregona</i> (&gt; 47 umol photons
 m<sup>-2</sup> s<sup>-1</sup>; M. Bracken,
 unpublished data). Nighttime samples were collected on nights when the
 pools were isolated by the tide after dark (measured irradiance levels of
 0 umol photons m<sup>-2</sup>
 s<sup>-1</sup>). The second set of
 measurements consisted of light and dark (Light-Dark) sampling during the
 daytime. Our protocols were similar to those used to calculate light-dark
 bottle estimates of productivity in oceanographic and limnological
 applications, modified for in-situ measurements of oxygen fluxes in tide
 pools to estimate net community production, community respiration, and
 gross community production. Measurements were started shortly after pools
 were isolated by the receding tide, when irradiance levels were sufficient
 to saturate photosynthesis by <i>N. oregona </i>(see above).
 Immediately after initial measurements of O<sub>2</sub>,
 irradiance, and temperature (see above), pools were covered with an opaque
 black plastic sheet (6-mil black polyurethane plastic sheeting, Film Gard,
 Berry Plastics, Evansville, Indiana, USA), which was anchored to the
 substratum with beach cobbles to ensure that no light entered the pool
 during the “Dark” incubation. Irradiance levels beneath the opaque plastic
 sheet were uniformly 0.0 mmol photons m<sup>-2</sup>
 s<sup>-1</sup>, and the presence of the plastic sheet did not
 appreciably alter tide pool temperatures during the “Dark” incubation
 (mean ± s.e.m. = -0.04 ± 0.16 °C; <i>t</i> = 0.2<i>,
 d.f.</i> = 4, <i>p </i>= 0.832). After an incubation
 period of at least 30 min (median = 45 min, maximum = 80 min), a second
 set of measurements was made, and the plastic sheet was removed,
 initiating a “Light” incubation of at least 30 min. At the end of the
 “Light” incubation, a final set of O<sub>2</sub>, irradiance,
 and temperature measurements was made.
description: <strong>Overview</strong> This
 dataset consists of two .csv files: Bracken_NCP_CR_20210722.csv,
 containing data on net community production (NCP) and community
 respiration (CR) and Bracken_GCP_20210722, containing data on gross
 community production (GCP).  <strong>Columns in
 Bracken_NCP_CR_20210722.csv include the
 following:</strong> Pool (categorical): These are
 the specific tide pools at John Brown's Beach, Sitka, Alaska, USA
 used in this study. Specific pool locations are as follows: (7)
 Lat 57.05597, Lon -135.37256; (10) Lat 57.05591, Lon -135.37274; (25)
 Lat 57.0555, Lon -135.3728; (30) Lat 57.0553, Lon -135.37279; (31) Lat
 57.05517, Lon -135.37256. Month (categorical): Months
 are numbered (Jan = 1, Feb = 2, ..., Dec = 12), reflecting sampled dates
 in 2018 and 2019: 3-12 Sep 2018; 16-21 Jan 2019; 26-31 Mar 2019; 28 Apr -
 2 May 2019; 11-14 Jun 2019; 7-11 Jul 2019; 5-7 Aug 2019; and 19-22 Sep
 2019. Note that 9A represents September 2018, whereas 9 represenents
 September 2019; 9B samples are an additional set of September 2019 samples
 that were not analyzed as part of the dataset in the paper.
 Category (categorical): These are the intervals analyzed. ID =
 Initial Dark, daytime dark sample for light-dark calculation; DR = Dark
 Recovery, daytime light sample for light-dark calculations; NightT = night
 sample for day-night calculation; DayT = day sample for day-night
 calculation. Delta_O2 (continuous): These are rates of
 change in dissolved oxygen concentrations in mg O2 per L per hr. Positive
 values represent increases in O2, and negative values represent decreases
 in O2. Light (continuous): These are initial
 photosynthetically active radiation irradiance measurements for each
 sampled interval in umol photons per m2 per second. DO
 (continuous): These are initial dissolved oxygen measurements for each
 sampled interval in mg O2 per L. Temp (continuous):
 These are initial temperature measurements for each sampled interval in
 deg C. <strong>Columns in
 Bracken_GCP_20210722.csv include the following:</strong>
 Pool (categorical): These are the specific tide pools at John
 Brown's Beach, Sitka, Alaska, USA used in this study. Specific pool
 locations are as follows: (7) Lat 57.05597, Lon -135.37256; (10)
 Lat 57.05591, Lon -135.37274; (25) Lat 57.0555, Lon -135.3728; (30)
 Lat 57.0553, Lon -135.37279; (31) Lat 57.05517, Lon -135.37256.
 Month (categorical): Months are numbered (Jan = 1, Feb = 2, ...,
 Dec = 12), reflecting sampled dates in 2018 and 2019: 3-12 Sep 2018; 16-21
 Jan 2019; 26-31 Mar 2019; 28 Apr - 2 May 2019; 11-14 Jun 2019; 7-11 Jul
 2019; 5-7 Aug 2019; and 19-22 Sep 2019. Note that 9A represents September
 2018, whereas 9 represenents September 2019. Category
 (categorical): These are the comparisons made in calculating estimates of
 gross community production (GCP), including LD (light-dark) and DN
 (day-night). GCP (continuous): These are calculated
 estimates of gross community production in mg O2 per L per hr.