Dataset: Green crab (Carcinus maenas) density from intertidal surveys in the Gulf of Maine during 1973, 2003, 2017-2018 and 2021

This dataset contains measurements of green crab (Carcinus maenas) density from rocky intertidal sites throughout the Gulf of Maine. Data were compiled from multiple sampling efforts conducted in 1973, 2003, 2017–2018, and 2021. Crab density is reported as the number of individuals observed per person-hour of standardized survey effort.

This dataset is part of a broader study conducted in the Gulf of Maine to investigate phenotypic plasticity of prey species in response to predator invasion and warming oceans:

1. Green crab surveys plus historical crab density data (this dataset) 
2. Green crab density from field studies at rocky intertidal sites from April 2019 to December 2021 (dataset 911365) 
3. Latitudinal (clinal) variation in Littorina obtusata shell thickness and tissue mass (dataset 990839)
4. Field experiment outplanting Littorina obtusata with predators (green crabs) to examine local and regional geographic variation in inducible defenses conducted from April to August 2021 (dataset 911221)
5. Morphological data from reciprocal transplant experiment in the field (dataset 990830)