The influence of artificial light at night (ALAN) on algal phenol concentrations can mediate herbivore-alga interactions

Artificial light at night (ALAN) is a human-induced factor affecting various biological complexity levels and species. Research on ALAN impact has focused on vertebrates and invertebrates, with less attention on primary producers like marine algae. The aim of our study was to evaluate the effect of ALAN on production of phenolic compounds in the red alga, Mazzaella laminarioides, and their indirect impact on the feeding behavior of the marine snail Tegula atra. Algae were exposed to the following treatments: natural day/night cycles, ALAN, and continuous darkness. We observed a higher phenolic concentration during high tide, in according with periods of feeding activity of herbivores. In comparison to algae exposed to natural day/night conditions, those exposed to ALAN showed the lowest concentrations of phenols. Tegula atra consumed significantly more algae than those exposed to ALAN, a result that is consistent with the preference trials, where algae exposed to ALAN was consumed more ..., Sampling and acclimation: Experimental organisms were collected during spring 2024 at “Las Conchitas” beach, Isla Negra, Valparaíso-Chile (33º26'19.8\" S, 71º41'19.9\" W). Blades of red algae (M. laminarioides; hereafter algae) of similar size were collected by hand and quickly brought to the laboratory. To avoid potential biases associated with reproductive stage or sex (65 - 67), and possible fragmentation, all the algae used were non-reproductive (i.e., vegetative thalli) and individual blades came from separate holdfasts. Black snails (T. atra, hereafter snails) were also collected manually, targeting a small size range (1.75 ± 0.19 cm shell height), which prevented potential biases associated with reproductive status. Snails were placed in coolers with seawater and contact aeration. Both organisms are abundant and can be found in the mid-intertidal zone, the algae typically on top of the rocks whereas the snails typically at the base of rocks, cracks and pools. In the laboratory..., , # The influence of artificial light at night (ALAN) on algal phenol concentrations can mediate herbivore-alga interactions

[https://doi.org/10.5061/dryad.wh70rxwz6](https://doi.org/10.5061/dryad.wh70rxwz6)

## Description of the data and file structure

This study focused on the influence of ALAN on the production of secondary metabolites (phenolic compounds) by the red alga*Mazzaella laminarioides*, and its indirect effects on the feeding behavior of consumers, the snail*Tegula atra*. We followed the variation of phenolic compounds in the alga, and then studied their variation when algal were exposed to: natural daylight/night, ALAN, and darkness. Algae were then used as food sources to assess snails’ food behavior

### Files and variables

#### File: DATA.xlsx

##### Description: 

**Sheet one:** Consumption assays (without choice of feed). Where we can find the following treatments (Column 2 “Treatment”):

LL: ALAN, DD: Complete dark, and LD: Natural light/night cycle

During 24 and...,