DOI: 10.5061/dryad.tdz08kq9t
title: Data from: Long term marine biodiversity monitoring in coastal Antarctica: Are fewer rare species recruiting?

description: The physical environment of nearshore Southern Ocean (coastal Antarctica)
 is altering rapidly in response to climate change, but also has other long
 cyclicity due to El Nino Southern Oscillation and Southern Annular Mode.
 Detecting biological responses to such physical change, which is complex
 in time and space, is very challenging not least because of remoteness,
 difficulty of access, frequency of iceberg destruction and short funding
 cycles but also the paucity of research stations with SCUBA (or ROV)
 facilities. At one of those few, Rothera, Adelaide Island on the West
 Antarctic Peninsula, we immersed arrays of artificial substrata
 (settlement panels) for 1 year repeatedly for over two decades. Whilst
 many ‘mature assemblages’ monitored at nearshore sites around the world,
 there are few of similar duration for recruitment and colonisation. We
 report the variability in annual biodiversity descriptive statistics with
 the crucial context of also recording adjacent long (here defined as
 &gt;1 decade) term seabed disturbance and biophysical oceanography at
 Rothera. We ask how variable is annual colonisation, recruitment and early
 community development in Antarctica's shallows, what aspect of
 recruitment changes over two decades and in what way? Of 40 recorded, most
 species recruiting to our panels at 12 m depth at Adelaide Island (67.568°
 S, 68.127° W) were rare, comprising cheilostome and cyclostome bryozoans,
 polychaetes, calcarea and demosponge sponges, hydroid cnidarians and
 ascidians. The most striking finding was a sustained decrease in total
 richness of recruits over time, mainly due to loss of rare species. Unlike
 losses of seasonal sea ice, iceberg disturbance and benthos mortality,
 such findings are unlikely to be climate-forced responses. This raises
 important questions of whether this is a chance finding, (the data only
 spans 20 years), driven by a recent complex of stressors and most of all
 is losing rare species a wider polar problem?
description: # Data from: Long term marine biodiversity monitoring in coastal
 Antarctica: Are fewer rare species recruiting? Dataset DOI:
 [10.5061/dryad.tdz08kq9t](10.5061/dryad.tdz08kq9t) ## Description of the
 data and file structure **This is a data set describing monitoring of
 marine biodiversity colonization on the seabed near Rothera station
 Antarctica from 2004-2024.** Between four and six high density perspex
 panels of size 14 cm x 14 cm were immersed and positioned on rocky
 substrata at 12 m depth at Adelaide Island, Antarctica (67.568° S, 68.127°
 W) using SCUBA diving. These were positioned next to large boulders in an
 attempt to offer some protection from iceberg scour. Such replicate panels
 were immersed across nine of the last 21 years up to 2024 (placed
 underwater for 12 months each beginning in the austral summer. Panels were
 all emersed at the same site (South Cove, Ryder Bay) for the same period
 (1 year) at 1 to 5 year intervals between 2004-2024.  All panels were
 immersed in the same down facing orientation, fixed to leave just 5 mm
 between the panel surface and the rocky substratum (thus excluding
 macro-predators). At the end of each year that the 4-6 replicate panels
 were immersed, they were recovered for analysis, to give a sample size of
 4-6 for each study year. All macroscopic life was identified to the
 highest taxonomic resolution from the central area of 10 cm x 10 cm of
 each panel by eye using high powered light microscopy (Leica M165c). Only
 biota in the central 10 cm x 10 cm area was recorded to minimise so-called
 edge effects influence by turbulent eddies at the periphery of the panel.
 The % cover was measured by covering all biota with an inelastic net
 marked out in mm2 so that the total number of mm2 occupied by each
 colonising species could be summed. Although these panel surfaces were
 very small areas relative to the size bay, they contained most of the
 encrusting species ever reported there, suggesting they are representative
 of the richness of the epifaunal assemblage. Here we report variability in
 annual biodiversity descriptive statistics of those panels in the context
 of seabed disturbance and biophysical oceanography at the same location
 and timing. Also shown are show weekly mean sea temperature (°C) at 15 m
 depth, the number of days the sea surface was frozen into ‘fast ice’ (sea
 ice duration), the ice scour anomaly (compared with mean ice scour over
 the study period) and duration of phytoplankton abundance (how many months
 each year that the biomass of phytoplankton at 15 m depth exceeded 200 mg
 per m3). The anomaly of ice scour was calculated using the formula (the
 value of ice scour in a given year – mean ice scour across study years) /
 mean ice scour across study years. ### Files and variables #### File:
 LTM_seabed_colonizarion_Antarctica_Barnes.xlsx **Description:** Three data
 sheet contain the raw and formatted data to reproduce the analyses.
 Datasheet (Tab) 1 contains the recruitment / colonization of 40 named
 marine species to panels in Antarctica by year. Datasheet (Tab) 2 is
 summary of associated biodiversity and environmental data. Datasheet (tab)
 3 is raw biodiversity and environmental data by replicate.
 1_LTM_panel_data_Rothera__Antarctica.csv is taxonomic group and species by
 replicate by year. * Group: taxonomic group of colonists. * species:
 Identification of each individual. * 2004 (C-H), 2005 (I-M) etc: number of
 colonists per replicate per year. 2_LTM_panel_data_Rothera__Antarctica.csv
 summary of associated biodiversity and environmental data * Year; year
 each panel with encrusting biodiversity was immersed in Southern Ocean *
 Density; number of recruits per cm2 per panel per stated year (in rows) *
 Abundance; abundance of recruits per panel per stated year (in rows) * %
 cover; space occupation of recruits per panel per stated year (in rows) *
 Richness; number of morphospecies per panel per stated year (in rows) *
 Rarity; number of species with &lt;1 per thousand recruits per panel per
 stated year (in rows) * Year of environmental records * Sea (fast) ice
 duration in days per year * Ice scour; number of iceberg-seabed collisions
 per year (out of 225 maximum possible) * Ice scour anomoly; sum of ((ice
 scour for given year)-(across year ice scour average)/(across year ice
 scour average) * Phytoplankton; number of months in which phytoplankton
 density exceeded 200mg per m3 at 15 m depth per year * Month for sea
 temperature records * Year for sea temperature records * Maximum sea
 temperature (degress C) at 15 m depth in stated year * Number of months in
 which sea temperature &gt;0C per year * Micro-algae phytoplankton duration
 (months &gt;0.2g m3) at 15 m per year
 3_LTM_panel_data_Rothera__Antarctica.csv is raw biodiversity and its
 matched environmental data. Each replicate panel is a seperate row * Year;
 year each panel with encrusting biodiversity was immersed in Southern
 Ocean * Density; number of recruits per cm2 per panel per stated year *
 Abundance; abundance of recruits per panel per stated year * % cover;
 space occupation of recruits per panel per stated year * Richness; number
 of morphospecies per panel per stated year * Rarity; number of species
 with &lt;1 per thousand recruits per panel per stated year (in rows)Sea
 (fast) ice duration in days per year * Sea ice; Sea (fast) ice duration in
 days per year * ice scour; number of iceberg-seabed collisions for that
 year of panel immersion (out of 225 maximum possible) * Ice scour anomoly;
 sum of ((ice scour for given year)-(across year ice scour average)/(across
 year ice scour average) * Max Sea temp; maximum sea temperature (degrees
 C) the year of panel immersion * Duration; Number of months in which sea
 temperature &gt;0C per year * Phytoplankton; number of months in which
 phytoplankton density exceeded 200mg per m3 at 15 m depth the year of
 panel immersion ## Access information Sea temperature and phytoplankton
 data was derived from the following sources: *
 [https://doi.org/10.5285/50ACB5B7-5B42-44CD-A98E-790BD367F204](https://doi.org/10.5285/50ACB5B7-5B42-44CD-A98E-790BD367F204)