DOI: 10.5061/dryad.x69p8czqw
title: Colour change and colour phases in Lethrinidae with insights into ecology

description: This dataset was collected using seabed stereo-baited remote underwater
 video systems (Stereo-BRUVS). Seabed stereo-BRUVS consist of two GoPro
 cameras mounted 80 cm apart on a horizontal base bar, each converging at
 an angle of four degrees to a common focal point. A galvanised steel mesh
 bait cage containing ~1 kg of crushed pilchards Sardinops sagax
 is attached to the end of a 1.5-m-long bait arm. Seabed stereo-BRUVS are
 deployed at least 200 m apart for a minimum of 60 minutes.  All
 videos were analysed using Eventmeasure software. Video processing
 commenced once seabed stereo-BRUVS had settled on the seabed, for a period
 of 60 minutes. All animals entering the field of view were identified to
 the lowest possible taxonomic level, and abundance was estimated using the
 conservative abundance metric MaxN, which is the maximum number of
 individuals of a given taxon in a single frame (Cappo et al. 2006). Fork
 length was measured in stereo with individuals measured where they were
 well positioned relative to the camera and not occluded by other
 individuals. An Excel database was then created containing the
 identifications and measurements (where possible) of all
 animals.  All observations of individuals from the family
 Lethrinidae were extracted from this database. These observations were
 reanalysed using EventMeasure to determine frequency of different colour
 phases (number of individuals currently in each colour phase),
 physiological colour change (individuals actively displaying physiological
 colour change while in frame) and the association of physiological colour
 change with feeding behaviour (individuals displaying colour change while
 feeding or approaching to feed). Pictures taken from the videos were
 subsequently processed using Adobe Photoshop 22.2 adjusting brightness,
 saturation and contrast. Distinction was made between two different colour
 phases, light (silver/pale) and any form of dark colour (partly or fully
 dark). No quantitative differentiation of patterns among dark colour
 phases was made, however, different patterns were qualitatively described.
 Individuals displaying any form of dark colour phase were counted at the
 moment of MaxN (maximum number of individuals observed in the frame at one
 time) or the highest cumulative MaxN moment in which physiological colour
 change occurred or dark colour phases were present to avoid multiple
 counts of the same individuals. Individuals that showed active
 physiological colour change were also marked during dark phases.
description: # Colour change and colour phases in Lethrinidae with insights into
 ecology
 [https://doi.org/10.5061/dryad.x69p8czqw](https://doi.org/10.5061/dryad.x69p8czqw) | Column header | Explanation | | ------------- | ----------- | | Metadata Sheet Columns | | | New Opcode | Standardised naming convention, to keep consistency between expeds | | Exped | Place, year and season of survey | | Date | Date of deployment | | Year | Year of deployment | | Month | Month of deployment | | USE? | Will be YES if a sample was recorded, NO if rig was lost, camera died, etc. Used to separate “no fish” from “no sample”. At least 1 camera recording for at least an hour. | | Lat | Latitude of deployment | | Long | Longitude of deployment | | Time in | Time at which the BRUVS rig was deployed | | Time out | Time at which the BRUVS rig was retrieved | | Depth | Depth in metres | | Location | discrete locations within the survey. | | MaxN Sheet Columns | | | New Opcode | Standardised naming convention, to keep consistency between expeds | | Concate | A combination of New Opcode and binomial name of the relevant organism | | Exped | Place, year and season of survey | | Frame | Video frame in which the organism was recorded | | Time (mins) | Time at which the organism was recorded | | Period time (mins) | Time organism was recorded after the start of processing | | Family | Family classification of the organism | | Genus | Genus classification of the organism | | Species | Species classification of the organism | | Binomial | Scientific name of the relevant organism | | Common Name | Common name of the relevant organism | | MaxN | Maximum number of individuals of this organism in a single video frame | | Has fed | Whether or not the organism fed on the bait | | Depth (m) | Depth at which BRUV was deployed | | cat | Taxonomic level to which individual was identified | | Endemics | Whether the individual is endemic to the region | | Colour change | The presence or absence of colour change | | Light Phase | The presence of absence of light colour phase individuals | | Light Phase Length | Measured length of light phase individuals. "n/a" signifies that there were no individuals displaying this colour phase to be measured | | Dark Phase | The presence of absence of dark colour phase individuals | | Dark Phase Length | Measured length of dark phase individuals "n/a" signifies that there were no individuals displaying this colour phase to be measured | | Dark Phase Feeding | Feeding by dark phase individuals | | Active Change | Actively changing colour phase while in field of view | | Changing While Feeding | Actively changing colour phase while feeding | | Behaviour | Notes on behaviour for each record, where relevant. "null" signifies that no behaviour notes were made for this record | ## Description of the data and file structure The main metrics in this dataset are abundance (number of individuals), length (measured fork length of individuals), and colour phase (light or dark). Abundance and length can be analysed at various scales within this dataset: they can be averaged by species, by individual BRUVS rig (labelled as "opcode"), by region (North West or Cocos), by season (month), or by year. How to calculate mean abundance per sample in MS Excel: * Create a pivot table including all relevant factors (MaxN, species, opcode, location, etc.) * Calculate mean TA (sum of MaxN) per sample * Create second pivot table using mean values Determine species composition (of lethrinids) * Create pivot table matrix of MaxN per Species per sample (opcode) * Add in other factors, e.g. exped, year, etc. * Calculate mean MaxN per species per sample (MaxN divided by no. of opcodes)