Brief description
The distribution of three sea cucumbers (H. whitmaei (Bell 1887), H. atra (Jaeger 1933) and S. chloronotus (Brandt 1835) in the vincinity of Coral Bay, Ningaloo Reef, Western Australia was measured. There was an emphasis on factors that may contribute to the heterogeneous distribution of H. whitmaei within broadly defined habitats and reasons for variable density estimates reported in the literature.Lineage
Maintenance and Update Frequency: notPlanned
Statement: -Distribution analysis-
The geographic position of individual sea cucumbers was determined using a modification of the manta tow - a rapid quantitative survey technique used to determine the abundance and/or densities of marine organisms. In this study manta tows were conducted in the traditional sense; however, instead of counting individual specimens, the position of each was recorded as a single global positioning system (GPS) way-point. To record geographic information relevant to individual species, two operators each holding a hand held GPS entered the postion of sea cucumber when the appropriate signal was given by the diver. In this case, the diver signaled the presence of one species by raising a green glove, or similarly the presence of another by raising a red glove. In situations where animals were too numerous to record individually, the GPS way-point was noted and the diver estimated the number of specimens according to the following categories: <10; <20 or <30 animals. This was typically the case for S. chloronotus which tended to maintain a concentrated pattern of distribution relative to H. whitmaei and H. atra. For geographic information software (GIS) purposes, an appropriate number of way-points were entered, so that on the aerial photographs the animals appear as a group of tightly clustered points.
Statement: Surveys conducted between August 2002 and April 2003, encompassed all sections of the inner-reef, including broadly defined habitats such as the inner lagoon (including open sand), the reef-flat (inner and outer), the inner reef slope and, where possible, the reef-crest. Certain sections including the deeper zones adjacent to Pt. Maud and the area west of the reef crest were not included in the surveys. Each of the areas included in the distribution surveys were determined prior to embarking and marked in the field with floating reference buoys. Within the zone identified by the buoys, parallel manta tow transects were conducted approximately every 30 to 50 m. This stratified sampling design enabled the survey to cover all habitats within an area encompassing approximately 750 ha of coral reef habitat.
On return to the laboratory, each of the way-points was plotted on a digitally recified aerial photograph to determine the extent and range of the distribution of the sea cucumber species.
Statement: -Population densities-
Traditional manta tow surveys consisting of 9 to 10 transects were conducted in three pre-determined locations between September 2001 and January 2002 (prior to the GPS modified surveys). Manta tows were conducted on the reef flat adjacent to Lotty's Lagoon, the outer reef at Glass Botton Boats (GBB) and adjacent to the reef crest at Pt. Maud. Each of the areas included in the survey were initially chosen based on the preferred habitats of H. whitmaei but nevertheless included habitats occupied also by H. atra and S. chloronotus. Each of the three species were surveyed (by manta tow) over distances of approximately 240 to 300 m, depending on the shape of the habitat under investigation. The area included in the final density estimates was calculated as the length of the transect by the width of the viewing area i.e. 1.5 m either side of the tow line to give a total width of 3 m.
In addition to the density measures obtained by traditional manta tow, densities based on the results of GPS modified surveys were estimated using ESRI ArcView 3.3 at two habitat scales: i) within areas of species aggregation (identified by Kernal Home Range analysis in Animal Movement), and ii) over the full extent of the habitats occupied.
Created: 25 07 2007
Data time period: 2001-10 to 2003-04
text: westlimit=113.73; southlimit=-23.21; eastlimit=113.78; northlimit=-23.1
Subjects
25 416003 |
25 416033 |
25 417001 |
AQUATIC ECOSYSTEMS |
BIOSPHERE |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
Habitat selection |
Holothuria (Halodeima) atra |
Holothuria whitmaei |
Oceans | Marine Biology | Marine Invertebrates |
Population Dynamics |
Population density survey |
Range Changes |
Reef Habitat |
SPECIES/POPULATION INTERACTIONS |
Spatial distribution |
Stichopus chloronotus |
black teatfish |
green fish |
lolly fish |
oceans |
User Contributed Tags
Login to tag this record with meaningful keywords to make it easier to discover
Other Information
global : 1fb514f0-3045-11dc-95ce-00188b4c0af8
Identifiers
- global : d5593420-3a50-11dc-8d63-00188b4c0af8
