|Witman, Jon D.||Brown University||Principal Investigator, Contact|
|Smith, Franz||Brown University||Contact|
|York, Amber D.||Woods Hole Oceanographic Institution (WHOI BCO-DMO)||BCO-DMO Data Manager|
This dataset contains percent cover of the barnacles (Megabalanus sp.) per 0.25 m2 area photo quadrat at 12 sites (6 m depth) in January 2015 and January 2016 in rocky subtidal habitats of the Galapagos Islands, Ecuador.
Percent cover data were obtained by the random dot method (200 dots per quadrat, Witman et al. 2010) with 18 replicate quadrats sampled per site. January 2016 data not worked up yet for 2 sites (Pinzon, Roca Cousins). Barnacle percent cover values have an upper bound of 100.
For more information about these sampling methods see:
Witman, J. D., Brandt, M. and Smith, F. (2010), Coupling between subtidal prey and consumers along a mesoscale upwelling gradient in the Galapagos Islands. Ecological Monographs, 80: 153–177. doi:10.1890/08-1922.1
Data are raw percent cover values, with no processing.
BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* split yy-MMM column into year (yyyy) and numeric month (MM)
* rounded percent cover to two decimal places
* changed some site names to be consistent with site location list (e.g. Baltra -> North Baltra)
* data were sorted alphabetically by site after naming modifications
* added lat lon from site list
|lon||Longitude of sampling site||decimal degrees|
|lat||Latitude of sampling site; west is negative||decimal degrees|
|year||Year sampling occured||unitless|
|month||Month sampling occurred||unitless|
|depth||Depth sampling occured||unitless|
|quadrat_num||Replicate quadrat number||unitless|
|barnacle_percent_cover||Percent cover of quadrat by barnacles (100% upper bound)||unitless|
|Dataset-specific Instrument Name|
|Generic Instrument Name|| |
|Generic Instrument Description|| |
All types of photographic equipment including stills, video, film and digital systems.
Subtidal sites surveyed: Champion -1.23683 -90.38498 Cousins -0.23696 -90.57309 Cuatro_Hermanos -0.84787 -90.74908 Daphne_Menor -0.39446 -90.35375 Islote_Gardner -1.32879 -90.29429 Guy_Fawkes -0.49897 -90.51222 La_Botella -1.28992 -90.49900 Las_Cuevas -1.26508 -90.35641 North_Baltra -0.41155 -90.27445 Pinzon -0.59087 -90.68595 Rocas_Beagle -0.41240 -90.62917 Rocas_Gordon -0.56596 -90.14065
Subtidal sites were surveyed. See measurement sites for more details.
The question addressed in this project is: Does the 2014-2015 El Niño cause a regime shift in Galapagos subtidal ecosystems? And if so, what thresholds are crossed to drive the change from rocky subtidal communities with abundant corals to a barnacle dominated regime? Regime shifts are non-linear "ecological surprises" in the sense that the endpoint is not predictable as a linear outcome of a driver variable. The working hypothesis for this project is that the forthcoming 2014-2015 El Niño will create non-linear effects that are negative for corals which bleach during extreme temperature variability of the El Niño Southern Oscillation (ENSO), but are positive for the benthic (bottom dwelling) food chain dependent on barnacles for food. The specific work in the Galapagos will contribute to the general understanding of non-linear effects of climate stress in marine ecosystems, which has been highlighted as a critical information gap needed to understand the effects of climate change on ecosystems. The study will also inform best practices for the conservation of corals, which are threatened worldwide by multiple stressors and cumulative direct, and indirect impacts.
Perturbations such as El Niños can drive ecosystems to a tipping point as thresholds are exceeded and a sudden transition to a different state (regime) occurs. Since the frequency of extreme El Niños is projected to increase with climate change, there is a pressing need to develop a more comprehensive understanding of how ENSOs affect marine communities in the context of climate change. Currently, the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center predicts a 70-80 % chance of an El Niño occurring during the northern hemisphere summer-winter of 2014-2015. This project leverages an existing quantitative baseline on benthic community structure in the Galapagos subtidal to address 12 predictions about community-ecosystem level impacts of the oncoming 2014-2015 El Niño. The research employs an observational-experimental approach to test the predictions and to discern if additional bleaching stress to corals and further increases in barnacles associated with this ENSO ultimately leads to an ecosystem state (regime) characterized by declining coral populations and increasing barnacles and their predators.