Brief description
Exclusions were attached to artificial substrata to investigate the relative effects of predation on the development of epifaunal communities at Portsea. Exclusions were black plastic mesh cages enclosing panels that were attached to rigs under the Portsea Pier. Bare control panels and cage controls where included in the experimental design. Cage controls had the bottom and half of the roof on the cage removed. There were 2 replicate panels of each treatment that were immersed for 2, 4 or 7 months and there were 6 runs of the experiment from October 1975 to November 1977. At the conclusion of each run of the experiment the panels were fixed in 4% formalin-seawater solution. In the laboratory, the number of individuals and percent cover of colonial species on each panel were recorded.Surveys identified that grazing fish were the most abundant predator of the epifaunal community at Portsea during the experiment. Predation significantly affected the pattern of establishment of the epifaunal community. There were fewer ascidian recruits and more diverse communities on bare control panels because fish predation prevented monopolisation of space by dominant ascidian competitors. On caged panels were there was no fish grazing, the survival of colonial ascidians was greater and the panels were dominated by arborescent bryozoans and ascidians.
Lineage
Statement: FISH SURVEYS:Estimates of the fish population size around the Portsea Pier was estimated using visual surveys by SCUBA divers. Surveys were conducted at approximately 1-2 week intervals over a 4-year period from November 1975 to December 1979. The survey covered a 15 x 5m area surrounding the experimental rigs. Fish species were identified, and the number of individuals and their total lengths were estimated. A small number of fishes were speared and taken back to the laboratory for gut analysis.
PANEL SAMPLING:
Percentage surface cover of epifaunal species on panels was estimated using a point sampling technique. This technique involved a thin pane of glass (180x180mm) divided into four 90x90mm quadrats. Twenty-five random points were placed in each quadrat. The glass was placed horizontally above the panel. A replicate pane of glass was placed 10mm below the first. Both panes of glass were held in place by a specifically designed 'slotted holder' approximately 30mm above the panel. A point on the upper glass pane was lined up with a point on the lower pane and the species beneath the 2 points on the panel was identified and given a score of 1. Twenty-five random points per quadrat were used for Run 1 and 2 of the experiment and either 50 or 100 random points per quadrat were used for the remaining runs.
Notes
CreditMartin, A.A., Dr
Issued: 25 02 1981
Data time period: 1975-10 to 1977-11
text: westlimit=144.727; southlimit=-38.327; eastlimit=144.727; northlimit=-38.327
text: uplimit=4.2; downlimit=1
Subjects
10 000000 |
11 000000 |
20 000000 |
22 000000 |
27 558003 |
28 401000 |
35 000000 |
35 013002 |
37 465002 |
ANIMALS/VERTEBRATES |
Ascidiacea |
BIOLOGICAL CLASSIFICATION |
BIOSPHERE |
Biosphere | Aquatic Habitat | Benthic Habitat | artifical substrata | pier piling |
Biosphere | Aquatic Habitat | Benthic Habitat | rocky substrata |
Biosphere | Ecological Dynamics | Competition |
Biosphere | Ecological Dynamics | Predation |
Biosphere | Ecological Dynamics | Succession |
Biosphere | Zoology | Invertebrates |
Bryozoa |
COMMUNITY DYNAMICS |
Community Structure |
Didemnum augusti |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
Elminius modestus |
Fish |
Hydrozoa |
Oceans | Marine Biology | Marine Invertebrates | epifauna |
Penicipelta vittiger |
Phyoxocephalidae |
Polychaeta |
Porifera |
Port Phillip Bay |
Portsea Pier |
Species Recruitment |
biota |
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Other Information
global : 9a56cc90-e354-11dc-97b4-00188b4c0af8
Identifiers
- global : fd9aa0f0-e4c2-11dc-9b6b-00188b4c0af8
