Brief description
A combination of surveys and experiments were used to determine the size distribution, recruitment, mortality and growth rates of Siphonaria diemenensis in 2 zones on the rocky shore at Griffith Point, San Remo, Victoria. One zone was in the high intertidal (Zone 2) and one was in the low intertidal area on the shore. There were 3 sites in Zone 1 and 2 sites in Zone 2 (see parent record for more details).A size frequency distribution was constructed for each site from surveys that recorded the size of all individuals every 2 months from October 1979 to December 1981. In addition to the sites in Zone 1 there were 12 permanent quadrats (50 x 50cm) which were surveyed in the same manner from December 1980 to December 1981. The sizes of recruits were similar in both Zones but the sizes of adults were significantly greater in Zone 2. In both years, the maximum density of recruits in Zone 1 was greater than in Zone 2. The mortality rate of adult limpets in Zone 2 was lower compared to limpets in Zone 1.
The growth rates (mm per month) of marked individuals were calculated for 3 time intervals; January-March, March-May and May-late July (Zone 2) and Mary-early August (Zone 1) in 1981. Limpets in Zone 2 grew faster (average 0.63 mm per month) than the limpets in Zone 1 (average 0.11mm per month).
In addition, an experiment was conducted in Zone 1 from May to July in 1981 to determine the effects of adult density and macroalgal cover on limpet recruitment. It was found that there was no effect of adult density but a significant interactive effect of algal cover and sampling date on the number of limpet recruits.
Lineage
Statement: SIZE DISTRIBUTION:Sizes were measured after all individuals in the vicinity of the sites had ceased movement during a low tide. The size frequency distribution for each site and survey date was converted to a cumulative frequency percentage distribution and plotted against size on probability paper. Points of inflexion in the cumulative frequency curves were determined and age cohorts extracted using the methods established by Cassie (1954).
MORTALITY:
Linear regressions of logarithm (base 10) of cohort numbers against time (months) were calculated for each study site and quadrat. Instantaneous mortality rates were determined from the slopes of these regressions in units of deaths per individual per month.
GROWTH RATE:
Individuals were marked and the size of each recaptured individual was measured to the nearest 0.1mm every 2 months from 25 January 1981 to 22 July 1981 (Zone 2) and to 4 August 1981 (Zone 1).
RECRUITMENT EXPERIMENT:
This experiment was set up in Zone 1 in enclosures that incorporated densities of 5, 15 and 30 adult limpets per enclosure (see parent record for enclosure details). Each density treatment had 3 replicate enclosures that had normal (< 10% cover) or zero algal cover. The number of new recruits in each enclosure was recorded every 2 weeks. Colour photographs were taken of each enclosure at the beginning and end of the experiment. Percent algae cover was estimated from the photographs using an image analyzer.
Notes
CreditLittlejohn, Murray, Dr
Purpose
The aim of this study was to describe the vertical distribution of Siphonaria diemenensis at Griffith Point and compare the population structure, growth, mortality and recruitment in Zone 1 and Zone 2.
The aim of this study was to describe the vertical distribution of Siphonaria diemenensis at Griffith Point and compare the population structure, growth, mortality and recruitment in Zone 1 and Zone 2.
Issued: 30 05 1985
Data time period: 1981-01 to 1981-12
text: westlimit=145.4; southlimit=-38.55; eastlimit=145.4; northlimit=-38.55
Subjects
24 488001 |
BIOSPHERE |
Biosphere | Aquatic Habitat | Benthic Habitat | rocky shore |
Biosphere | Ecological Dynamics | Competition | intraspecific |
Biosphere | Ecological Dynamics | Feeding Habitat | food availabiltiy |
Biosphere | Ecological Dynamics | Life History |
Biosphere | Zoology | Invertebrates |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
Griffith Point |
Oceans | Marine Biology | Marine Invertebrates |
Oceans | Marine Biology | Marine Invertebrates | gastropoda | limpet |
Population Dynamics |
SPECIES/POPULATION INTERACTIONS |
San Remo |
Siphonaria diemenensis |
biota |
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Other Information
global : 7423cda0-e59a-11dc-a14a-00188b4c0af8
Identifiers
- global : d008e890-e981-11dc-825d-00188b4c0af8
