Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Project Information
• Funding

The parameters TidBitID, Block, TrtGroup, HerbivoreTreat, TempTreat, NutrientTreat are only available for the period 2019-06 to 2019-08.

Temperature data collected by automated temperature dataloggers deployed in the bottoms of intertidal rock tide pools, set to sample at 15 minute intervals. Sensors were secured with screws in rock anchors, and remained submerged in pools at all times.

Latitude and longitude values for each of the tide pools used in the field experiment carried out at Bodega Marine Reserve, Bodega Bay in northern California, USA (38.31633326339228, -123.07227140000002). The locations were collected with a Garmin eTrex handheld GPS, using the WGS84 coordinate system.

TrtGroup - Coding variable for treatment type. A numeric value indicating each of 8 unique combinations of HerbivoreTreat, TempTreat, and NutrientTreat.

HerbivoreTreat - Coding variable for herbivore density treatment (Low or High). The High treatment level contains approximately twice the normal number of mobile grazers (limpets and littorine snails) as unmanipulated pools based on preliminary surveys. The Low treatment pools contained a near-zero number of mobile grazers maintained by repeated visits to the pool to manually pick out mobile grazers.

TempTreat - Coding variable for temperature treatment (Ambient or Warmed). Warmed treatment pools had a 60W heating element that heated the pool during daytime low tides, with a targeted 1-2 degree Celsius increase above ambient temperature conditions. Ambient treatment pools did not have temperature manipulated.

NutrientTreat – Coding variable for nutrient treatment (Control or Increased). The Increased treatment received slow-release nitrogen fertilizer to mimic increased coastal ocean nutrient supply. Control treatments were unmanipulated.

HOBOware 3.7.13 was used to download data from the sensors, and data were collated into CSV files using scripts written in R version 3.5.

Humans are modifying marine food webs both from the top-down, by reducing consumer abundances, and from the bottom-up, by adding nutrients to coastal habitats. Predicting these impacts is complicated because herbivores affect primary producers both from the top-down, by eating them, and from the bottom-up, by recycling nutrients and facilitating the recruitment of algae into local marine ecosystems. This project uses experimental manipulations along a natural gradient in nutrient availability on the California coast to evaluate the complex interactions between top-down and bottom-up processes in marine communities. This project includes experiments and outreach in a location with substantial exposure to the public, and the investigators will work with community and university outreach personnel to communicate this research to broader audiences. Specifically, the project includes mechanisms for curriculum development and outreach and will train undergraduate and graduate students in marine science.

The investigators are implementing a suite of innovative approaches to understand the multiple roles that herbivores play in marine systems. Traditional experimental methods for herbivore removal result in the loss of both the consumptive and facilitative effects of herbivores. In contrast, the investigators' experimental design allows them to partition the different effects of herbivores on marine primary producers. These methods, including observations, experiments, and modeling approaches, allow researchers to (i) calculate the relative importance of herbivores' consumptive and facilitative effects on algal diversity and abundance; (ii) determine the effects of temperature, nutrients, and herbivores on the microbial community; and (iii) evaluate the relative importance of internal processes and spatial subsidies.