These datasets represent the time to steady state photosynthesis (photosynthetic induction time) of Porites astreoides colonies classified as inside or outside of octocoral canopies. These data were used to test for the potential effect of light regimes created by octocoral canopies on the photophysiology of autotrophic taxa within the understories of octocoral forests. Additionally, these datasets contain information on the octocoral community surrounding each P. astreoides colony. Data was col...
Show moreLocation:
Lameshur Bay St. John, U.S. Virgin Islands at ~ 7.0 ± 0.5-m depth
Research conducted from the University of the Virgin Islands Marine Station in Lameshure Bay during July – August 2019.
Methods & Sampling:
At each site (White Point, Tektite, Cabritte Horn) corals were haphazardly selected and categorized as within "dense" or "sparse" octocoral canopies. Colonies were categorized as within dense canopies if they were shaded by at least one octocoral colony ≥ 25 cm tall when it flexed in routine oscillatory water flow. Preliminary surveys showed that colonies of Porites astreoides (urn:lsid:marinespecies.org:taxname:288889) met this criterion when the distance from the nearest tall octocoral was less than half the height of the octocoral colony. The distance between P. astreoides colonies and the nearest octocoral was measured to categorize colonies of P. astreoides as within or outside the understory habitat. A single induction curve was performed on each P. astreoides on one of 16 days during July and August 2019. Sampled colonies were > 4 cm in diameter to provide space on the colony surface for the placement of the fiber-optic probe (5 mm diameter) attached to the Diving Pulse Amplitude-Modulation (PAM) fluorometer (Heinz Walz, GmbH) that was used to measure induction time. To standardize the light environment of samples all induction curves were performed between 09:00 and 11:00 hrs on clear cloudless days. In this study actinic light from the Diving PAM was set to 896 µmol photons m-2 s-1 during the induction protocol. There was a two-minute rest period between the first saturation pulse assessing Fm and the initiation of actinic light. Once turned-on, actinic light was continuously delivered for 17 minutes with a total of 13 saturating pulses being delivered one every 1.4 minutes.
Instruments:
PVC Quadrats (1 m2)
Transect tapes
Measuring ribbons with mm graduations
Underwater Fluorometer Diving-PAM (Heinz Walz GmbH)
Girard, J., Edmunds, P. J. (2023) Steady state photosynthesis (photosynthetic induction time) from Porites astreoides colonies in St. John, US Virgin Islands from July to August of 2019. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2023-03-21 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.892286.1 [access date]
Terms of Use
This dataset is licensed under Creative Commons Attribution 4.0.
If you wish to use this dataset, it is highly recommended that you contact the original principal investigators (PI). Should the relevant PI be unavailable, please contact BCO-DMO (info@bco-dmo.org) for additional guidance. For general guidance please see the BCO-DMO Terms of Use document.