DOI: 10.5281/zenodo.14885586
title: Giant kelp forests act as natural barriers to motorboat noise: Dataset

description: Description of the data and file structure

The "GiantKelpForestData" dataset includes the following sheets:



"SPL": Contains sound pressure level (SPL) data along with the following variables:



"year"; "area"; "transect"; "distance_hydrophone_boat" for LMM 



"HydrophoneCalibration": Contains SPL values for each boat pass recorded by each hydrophone to compare the hydrophones with an ANOVA

"KelpDensity": Includes the number of individual kelp counted in each quadrant (2 per transect point) to estimate density

"N°Pneumatocyst": Records the height of kelp plants where pneumatocysts were counted to estimate density


The "PSD_kelp" and "PSD_control" files contain power spectral density (PSD) values for each area (kelp forest and control) for the years 2022 and 2024. For visualization, the PSD values expressed in dB were used.

Files and variables

File: PSD_kelp.csv

Description: 
Variables



year: year of data collection

area: study area (kelp forest/control area)

transect: transect number 

point: point transect where measurements were taken

frequency: frequency in Hz 

psd (uPa): psd value in uPa

psd (dB): psd value in dB


File: PSD_control.csv

Description: 



year: year of data collection

area: study area (kelp forest/control area)

transect:  transect number 

point: point transect where measurements were taken

frequency:  frequency in Hz 

psd (uPa): psd value in uPa

psd (dB): psd value in dB


File: GianKelpForestData.xlsx

Description: 
Variables



year:  year of data collection

area:  study area (kelp forest/control area)

transect:  transect number

point: point transect where measurements were taken

superficial_distance: surface distance between the boat and the hydrophone's location

depth: hydrophone depth



distance_hydrophone_boat: Distance between the hydrophone and the boat, calculated using depth data and the surface distance between the boat and the hydrophone's location ("superficial_distance"). This value represents the hypotenuse.




SPL: sound pressure level value
description: The world’s coastal areas are threatened by a variety of pollutants, including anthropogenic noise. To mitigate adverse effects of noise pollution on marine life, artificial bubble curtains are used in industrial contexts, such as offshore construction, to reduce noise propagation. In this study, we evaluate whether the giant kelp Macrocystis pyrifera, which possesses airbladders that aid flotation, effectively attenuates motorboat noise and could act as a natural sound barrier. We use hydrophones to compare motorboat noise attenuation along 60 m transects in a M. pyrifera forest and an adjacent control area without kelp in Algarrobo, central Chile. We found a significant reduction in the sound pressure level (SPL) of motorboat noise within the kelp forest, with a 6.02 dB difference at 60 m distance from the boat's passage compared to the control area. Motorboat noise was attenuated by M. pyrifera from 0.19 kHz to the maximum frequency measured (24 kHz). The peak frequencies of the motorboat noise signal in both areas (0.05–5 kHz), overlapped with the sensitivity frequency range of fish invertebrates and marine mammals, such as sea lions. Our results show, for the first time, the role of M. pyrifera in attenuating motorboat noise. Thus, highlighting an unexpected ecosystem function of kelp that may contribute to creating quieter environments for species associated with them, thus offering a nature-based solution to manage motorboat noise in temperate coastal areas.