Brief description
Interactions between native and introduced species can help to elucidate the impact of exotic species on the broader community. This work examines utilisation of an introduced gastropod, the New Zealand screwshell (Maoricolpus roseus) by native hermit crabs in eastern Tasmania. Variation in shell occupancy by hermit crabs was examined across different depths (10, 20, 30 and 40m) within a single site (Dennes Point, SE Tasmania). Sediment cores were taken from 10 and 20 m to compare sediment size structure. A sediment preference trial using the hermit crab Paguristes tuberculatus was also carried out (using sediment from 10m and 20m) to try and determine the low level of hermit crab occupancy at 20m (compared with that at 10m).Lineage
Maintenance and Update Frequency: notPlanned
Statement: Maoricolpus roseus were collected from 1 site in south eastern Tasmania using a modified scallop dredge towed at an average speed of 1 knot for a period of 5 minutes:
Dennes Point 43°03.618 S 147°19.703 E
(taken at 10, 20, 30 and 40m)
Statement: Sediment size
4 sediment cores of 150mm diameter x 100mm deep were taken from both the 10m and 20m depths at Dennes Point by SCUBA divers.
Cores were passed over a standard sieve series ranging from 2mm to 63µm. The relative abundance of each fraction was determined after drying samples at 55°C for 48 hours.
Statement: A sub-sample of approx 300 Maoricolpus roseus shells were used from each site.
Shell length and width were measured to the nearest 0.1 mm using Vernier callipers (shell length = longest distance of the shell from apex to anterior and width = widest part, below aperture).
Shell weight was measured to the nearest 0.01g after drying at 110°C for 24 hours.
Spire damage was given a relative score of 0-3.
Shells were also scored as live, dead and available or dead and unavailable.
Shells were broken, and if hermit crabs were present, they were identified to species, sexed and carapace measured with Vernier callipers to the nearest 0.1mm.
Statement: Sediment preference trial using the hermit crab Paguristes tuberculatus
Two substrate types (sediment taken at 10m and 20m) were placed in a plastic container (165x110x55mm) separated by a 15mm plastic divider in the middle of the container. Seawater at 14°C was added to each of the 28 replicate containers. Individual P. tuberculatus were placed in the middle of each container. The substratum type occupied was recorded at 1,2,3,4,5,6,12,24 and 48 hours - with the final sediment type occupied classified as preferred.
Notes
CreditSchool of Zoology, University of Tasmania
Credit
Natural Heritage Trust (NHT) Grant
Natural Heritage Trust (NHT) Grant
Purpose
To examine the association between Maoricolpus roseus and hermit crabs - and thereby identify potential impacts of this introduced screwshell on native populations of hermit crabs in eastern Tasmania - specifically looking at depth-related variation in occupancy and utilisation of M. roseus shells by hermit crabs.
To examine the association between Maoricolpus roseus and hermit crabs - and thereby identify potential impacts of this introduced screwshell on native populations of hermit crabs in eastern Tasmania - specifically looking at depth-related variation in occupancy and utilisation of M. roseus shells by hermit crabs.
Created: 27 05 2008
Data time period: 2003 to 2003
text: westlimit=147.2; southlimit=-43.1; eastlimit=147.5; northlimit=-42.7
text: uplimit=40; downlimit=10
Subjects
24 079001 |
ANIMALS/INVERTEBRATES |
ARTHROPODS |
BIOLOGICAL CLASSIFICATION |
Biological Sciences |
Crustaceans |
EARTH SCIENCE |
Ecological Applications |
Ecology |
Environmental Sciences |
Hermit crab occupancy |
Invasive Species Ecology |
Mollusks |
Maoricolpus roseus |
Marine and Estuarine Ecology (Incl. Marine Ichthyology) |
Shell length |
Shell weight |
Shell width |
biota |
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Other Information
Identifiers
- global : 2a78d8d0-2c58-11dd-bcd1-00188b4c0af8
