Distribution patterns of subtidal macrobenthos in the Tsitsikamma National Park
Citation
Heyns-Veale E, Coetzer W (2019). Distribution patterns of subtidal macrobenthos in the Tsitsikamma National Park. Version 1.8. The South African Institute for Aquatic Biodiversity. Sampling event dataset https://doi.org/10.15468/fa9wst accessed via GBIF.org on 2024-10-06.Description
Subtidal macrobenthos was sampled in the Tsitsikamma National Park between 2009 and 2012 to compare shallow (11–25 m) and deep (45–75 m) sites. The resultant records of sampling events, photographic images of the sea floor, and invertebrate and algal species occurrences constitute this dataset. See Heyns et al. (2016). The following classes of data are represented. DwC Event Core: A parent sampling event represents a sample station in which 30 child sampling events / photoquadrats were randomly selected. There are 6 sample stations / parent events (i.e. 180 child sampling events / photoquadrats) for the deep site and 6 parent events (180 child sampling events / photoquadrats) for the shallow site. A 0.2m^2 photoquadrat on each photo was sampled using Coral Point Count for Excel, using 54 random points. DwC Occurrence Extension: An occurrence record represents the percentage cover of a species calculated from the 54 random points falling in the 0.2m^2 photoquadrat (i.e. the individual species points from each photoquadrat have not been published). DwC Extended Measurement or Fact Extension: Each record represents the percentage cover, in the 0.2m^2 photoquadrat, of the following elements (either Tape/Wand/Shadow), abiotic features (e.g. shells, substrate) or biodiversity that could not be identified, even at a high level. DwC Audubon Media Description: Each record represents the digital photograph containing the 0.2m^2 photoquadrat.Sampling Description
Study Extent
The shallow reef site (11 - 25 m) was situated just east of the Storms River mouth (-34.0198, 23.9034) and the deep reef site (45 - 75 m) was about 1 km south west of the Storms River mouth.Sampling
Prior to sampling, both reef sites were bathymetrically mapped with a GPS-linked echo sounder and a 300 × 300 m grid was overlaid on the mapped sites. Each grid was classified according to profile (high or low), and sampling followed a stratified random approach, with even allocation of sampling effort between reef sites and high and low profile reefs.Method steps
- Assemblage composition The species compositions of the macrobenthic assemblages were determined by estimating percentage cover from photoquadrats collected at six sample stations within each reef site. Photoquadrats on the shallow reef site were obtained by SCUBA divers. From the midpoint of each station, divers swam 25 meters in eight predefined directions. Eight to ten photographs were then haphazardly taken around the 25-m distance mark using a Canon G9 camera (12.1 meg- apixels) mounted on a tripod. The tripod setup maintained a set distance from the substrate and sampled an area of ca. 0.33 m2. On the deep reef, photoquadrats were obtained with a ROV (Falcon Seaeye: 12177) fitted with a 1Cam (SubC Control; 12.3 megapixel HD camera). The 1Cam, which could be orientated to capture benthic images at a 90° angle, was fitted with two laser pointers, thus permitting size approximation of the sampled area. Due to strong currents and restricted maneuverability, sampling at each deep reef station was conducted along a single 100-m transect, in contrast to the method employed at the shallow reef site. Along each transect, the ROV captured between 100 and 150 photoquadrats within 2 m of either side of the transect line. Thirty photographs were selected randomly from each sample station, amounting to 180 photoquadrats per reef site. Photoquadrats were calibrated in Coral Point Count with Excel extensions (CPCe 4.1) and 56 × 31 cm (0.2 m2) blocks were superimposed onto individual images. A species accumulation curve was plotted to estimate the number of points required to identify 95 % of the macrobenthic species per photoquadrat, which indicated that 54 points were required. Under each point, individuals or colonies were identified to the nearest taxon (noting substrate cover where applicable). Environmental variables During November 2011 and February 2012, light intensity (photosynthetically active radiation; 400–700 nm) was measured at three randomly selected sample stations from both the shallow and deep reef sites. Light intensity measurements were taken by employing a LICOR LI-193 Spherical Quantum Sensor. Temperature data were recorded by divers on the shallow reef, and a temperature probe (Onset HOBO Pro v2) was attached to the ROV to obtain temperature data when deep reef photoquadrats were collected. Reef profiles for each sampling station were estimated by divers on the shallow reef and from the ROV footage on the deep reef. The overlay from the ROV provided accurate depth measurements and allowed for estimates of the deep reef profile. Substrate type was estimated as percentage cover obtained from the photoquadrats. Depth was recorded by divers at the beginning and end of each transect. Care was taken to follow a depth contour when conducting all transects with the ROV, thereby standardizing depth during sampling. To summarize, data for temperature, reef profile, depth and substrate type were collected from at each sampling station. In contrast, light intensities were extrapolated according to station depth, from light profiles constructed from data collected during two seasons from three stations per reef, as indicated above.
Taxonomic Coverages
Marine macrobenthos identifiable from photoquadrats
-
Codiaceaecommon name: Green algae rank: family
-
Anthozoarank: class
-
Tunicatacommon name: Acsidians rank: subphylum
-
Bryozoarank: phylum
-
Brachiopodacommon name: Lampshells rank: phylum
-
Hydrozoacommon name: Hydroids rank: class
-
Echinodermatacommon name: Echinoderms rank: phylum
-
Gastropodarank: class
-
Poriferacommon name: Sponges rank: phylum
-
Dictyotaceaecommon name: Brown algae rank: family
-
Florideophyceaecommon name: Red algae rank: class
Geographic Coverages
Photoquadrats were collected just offshore from the Storms River mouth, inside the Tsitsikamma National Park marine protected area, South Africa, between 11 - 25 and 45 - 75 m depth.
Bibliographic Citations
Contacts
Elodie Heyns-Vealeoriginator
position: Researcher
KwaZulu-Natal Museum
237 Jabu Ndlovu Street
Pietermaritzburg
3201
KwaZulu-Natal
ZA
Telephone: + 27 33 3410523
email: eheyns-veale@nmsa.org.za
homepage: http://www.nmsa.org.za/
userId: https://orcid.org/0000-0001-8208-7610
Willem Coetzer
metadata author
position: Biodiversity Information Manager
South African Institute for Aquatic Biodiversity
Somerset Street
Grahamstown
6139
Eastern Cape
ZA
Telephone: +27 46 603 5841
email: w.coetzer@saiab.ac.za
homepage: http://www.saiab.ac.za
userId: https://orcid.org/0000-0003-2214-3910
Willem Coetzer
processor
position: Biodiversity Information Manager
South African Institute for Aquatic Biodiversity
Somerset Street
Grahamstown
6139
Eastern Cape
ZA
Telephone: +27 46 603 5841
email: w.coetzer@saiab.ac.za
homepage: http://www.saiab.ac.za
userId: https://orcid.org/0000-0003-2214-3910
Elodie Heyns-Veale
administrative point of contact
position: Researcher
KwaZulu-Natal Museum
237 Jabu Ndlovu Street
Pietermaritzburg
3201
KwaZulu-Natal
ZA
Telephone: + 27 33 3410523
email: eheyns-veale@nmsa.org.za
homepage: http://www.nmsa.org.za/
userId: https://orcid.org/0000-0001-8208-7610