Brief description
Predation on newly settled individuals has been shown to shape sessile invertebrate communities of the northeast coast of North America. This study tests if this response can also be observed at other geographic locations that support different assemblage of sessile invertebrates. The effects of predation in early post-settlement assemblages were tested at two locations in Victoria; Workshops Pier, Williamstown and Queenscliff Pier, Queenscliff during the summer of 2005-2006. At each site, early post-settlement assemblages of sessile invertebrates were established and subsequently exposed to a series of predation exclusion treatments of varying durations. This dataset gives the abundances of sessile invertebrates on plates at Williamstown Pier after the initial 4 day settlement period, and after subsequent exposure to 3, 15 and 35 days exposure to three predation exclusion treatments. The predation treatments were i) uncaged, no predator exclusion, ii) full 2 mm mesh cage, total predator exclusion and iii) full 10 mm mesh cage, exclusion of large predators only. In addition two cage control treatments were established to identify if the cages themselves caused a change in the sessile invertebrate assemblages. Cage controls were partial cages constructed from both 2 mm and 10 mm mesh. The results indicated that, although predators were common, predation did not exert a strong influence on sessile invertebrate communities at Williamstown.Lineage
Maintenance and Update Frequency: notPlanned
Statement: Roughened black Perspex plates (110 x 110 x 15 mm) were used to establish sessile invertebrate assemblages. During the initial settlement period plates were bolted onto PVC panels (800 x 800 x 5mm) at least 6 mm apart and suspended in the water column with the developing colonies facing the sediment surface. Plates were then transferred to pylons where they could be accessed by predators, and given caging treatments. Square cages (130 mm x 130 mm x 150 mm height) were constructed using either 10 mm mesh plastic Gutter Guard TM or 2 mm mesh flyscreen. Unlike the Gutter Guard TM the flyscreen was not rigid so an internal frame was built with the Gutter Guard TM which was then completely covered with the 2 mm mesh flyscreen. Partial cages had half of the roof and half of two side walls removed to allow predators access to plates whilst leaving as much of the cage intact as possible. Species identification and counts were made using a binocular dissecting microscope.
Statement: This dataset gives the abundances of sessile invertebrates on plates deployed at Workshops Pier, Williamstown, Victoria. Abundances are given after the initial 4 day settlement period and 3, 15 and 35 days after these initial assemblages were exposed to five predation exclusion treatments: i) no cage, no exclusion of predators; ii) full 2 mm mesh cage, total exclusion of predators; iii) full 10 mm mesh cage, exclusion of large predators only; iv) partial 2 mm mesh cage, cage control; v) partial 10 mm mesh cage, cage control. The cage control treatments were established to identify if the cages themselves caused a change in the sessile invertebrate assemblages. Studies were carried out between mid December 2005 and late January 2006
Sessile invertebrate assemblages were established on roughened Perspex plates (110 x 110 x 15 mm) attached to a PVC backing panel (800 x 800 x 5mm) and suspended in the water column at a minimum depth of 1-3 m. To minimise sedimentation on the assemblages the panels were positioned so that the developing colonies faced the sediment. Panels were suspended in the water column to restrict assess of benthic predators to the plates during the initial settlement period.
After four days, six plates were removed to assess the initial assemblage and the remaining plates were randomly allocated to the 5 predation exclusion treatments. Each of the 5 treatments was applied to 6 replicate plates. The plates were then randomly assigned to one of 14 pylons and attached at 1, 2 or 3 m below the water surface at low tide. The experiment was repeated three times, exposing plates to the experimental treatment for 3, 15 or 35 days.
At the end of each experiment the plates were retrieved and immediately sealed and returned to the laboratory for identification and enumeration of sessile invertebrates or mobile animals on each plate using a binocular dissecting microscope. The number of individuals on the entire plate was counted, excluding the 5 mm perimeter of the plate. The abundance of colonial species was quantified as percentage cover for plates that had been deployed for 35 days in each of the experimental treatments. This was done by placing a 100 x 100 mm grid of 100 equal sized squares above the plate and counting the number of times the intersecting lines overlaid a portion of a colonial species.
The data columns in the dataset are: Pylon (1-14); Depth (1, 2, 3 m); Treatment (UC, uncaged; C2, 2 mm mesh full cage; C10, 10 mm mesh full cage, PC2, 2 mm mesh partial cage; PC10, 10 mm mesh partial cage control); Duration (Initial, 3, 14, 35). The remaining columns give the number of individuals per plate for each identified taxa. Percentage cover rather than abundance is reported for colonial taxa at day 35, as individual colonies could no longer be distinguished.
Note that this dataset includes rare taxa not analysed in the associated publication (Sams and Keough, 2007).
For more details on the methods and experimental design see
Sams, M.A and Keough, M.J. (2007) Predation during early post settlement varies in importance for shaping marine sessile invertebrate communities, Marine Ecology Progress Series. 348:85-101.
Sams, M.A. Predation during early post settlement: an important process shaping marine sessile communities? HonoursThesis, University of Melbourne.
b. Scale: counts are expressed as either number of individuals per plate or as percentage cover
c. Media Types: Not Relevant
d. Date:
e. Dates of various parts of the process:
Colonies established over 4 days in mid December 2005 at Williamstown
2. Processing Steps:
a. Intermediate processing steps (after data capture): Nil
b. Methods used to generate final product: Not Relevant
Notes
CreditParks Victoria gave permission to use Workshops Pier, Williamstown, and Queenscliff Pier, Queenscliff. Various people provided assisted in the field including A. O'Brien, K. Blackman, D. Semmens, E. Bone and E. Broughton, and B. Loughman provided assistance in the laboratory.
Purpose
To assess the effects of predation on recently settled sessile invertebrate assemblages at Williamstown, Victoria
To assess the effects of predation on recently settled sessile invertebrate assemblages at Williamstown, Victoria
Created: 14 03 2007
Data time period: 2006-12-15 to 2007-01-30
text: westlimit=144.90797; southlimit=-37.86094; eastlimit=144.90797; northlimit=-37.86094
text: uplimit=6; downlimit=1
Subjects
20 000000 |
20 331013 |
20 331032 |
20 332029 |
20 432002 |
22 085000 |
35 000000 |
35 002020 |
35 010001 |
35 013000 |
35 013019 |
35 032041 |
35 033006 |
Ascidiacea |
Ascidiella aspersa |
BIOSPHERE |
Biosphere | Ecological Dynamics | Predation |
Botryllus schlosseri |
Bryozoa |
Bugula flabellata |
Bugula neritina |
Bugula stolonifera |
COMMUNITY DYNAMICS |
Community Structure |
Ciona intestinalis |
Didemnidae |
Diplosoma listerianum |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
Oceans | Marine Biology | Marine Invertebrates |
Post-settlement mortality |
Pyura stolonifera |
Species Recruitment |
Serpulidae |
Tricellaria porteri |
Watersipora subtorquata |
Williamstown, Victoria |
biota |
depth |
duration |
experimental_treatment |
pylon |
taxonomic_group_count |
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Identifiers
- global : 7b2e2280-189f-11dc-a8fb-00188b4c0af8
