Demography and dynamics of Giant Kelp cohorts across four decades: Lessons for conservation and resilience planning

Kelp forests throughout many temperate zones are in decline due to various human stressors, chiefly marine warming. Conservation measures, including restoration, are presently of great interest and focus on both historical and novel methodologies. Of paramount importance for these efforts is an understanding of the mechanics of kelp decline to identify the factors and triggers leading to stepwise declines and thus support the development and spatial priorities of strategic intervention to facilitate resilience. Here, we utilized a unique dataset documenting the demographic dynamics of giant kelp, Macrocystis pyrifera, in response to multiple disturbances across >40 years off San Diego (California, USA). The recruitment and life history of >14,000 individuals were used to evaluate cohort structure, size, and longevity forced by algal community structure and disturbance. Cohort dynamics varied spatially by depth and study subregion, thus aiding the identification of areas to priorit..., , # Demography and dynamics of Giant Kelp cohorts across four decades: Lessons for conservation and resilience planning

Dataset DOI: [10.5061/dryad.fttdz096d](https://doi.org/10.5061/dryad.fttdz096d)

## Description of the data and file structure

This dataset includes algal data collected across 20 sites off San Diego, CA, USA. The data were collected from 1984 to 2024 at depths between 8 and 21 meters along permanent leaded transect lines. The transect lines are described in the article text. Each site consists of 4 leaded lines (A, B, C, D) that are 25 meters long and 4 meters wide. Data are recorded in 10 quadrats (sampling units) that are 5 meters along the line and 2 meters on each side of the line. Therefore, 400 square meters are sampled at each site along 4 transects that are each 100 square meters in area. Transect lines are oriented perpendicular to the shore, and ‘A’ lines are located at the northern end, with lines ‘B’, ‘C’, and ‘D’ located progressively to the south. The ze...,