Cascading effects of global climate change on near shore benthic communities in the Antarctic

Metadata record for data from ASAC Project 2300

See the link below for public details on this project.

---- Public Summary from Project----

Antarctic reefs, like their tropical counterparts, harbour a high diversity of animal life. For the first time we will determine how global warming will affect food availability to the animals which comprise the structural components of the reefs. Ultimately, we wish to predict the cascading effect through the community as one component changes.

With the confirmation that sponges in Antarctic waters graze on ultraplankton there is now a global overview that sponges are the primary benthic organism that is responsible for linking the pelagic microbial food web to the benthos. Like other shallow water demosponges, sponges in Antarctica are omnivorous sponges that graze nonselectively, consuming both heterotrophic and phototrophic organisms. Retention efficiencies of ultraplankton are similar to other sponges measured using similar techniques from shallow water to the deep sea, the tropics to boreal waters.

The large amounts of water processed by these benthic suspension feeders and their diet places these sponges squarely within the functional group of organisms that link the pelagic microbial food web to the benthos. The number of macroinvertebrates that have been shown to side- step the microbial loop and directly utilize the base of the microbial food web as a primary food source is ever growing and currently includes demosponges, ascidians, soft corals, and bivalves. Dense macroinvertebrate communities dominated by demosponges and corals in shallow water have been shown to remove as much as 90% of the ultraplankton from the water that passes over them. The daily fluxes of ultraplankton to these communities ranges from 9 to 1970 mg C day-1 m-2. We conservatively estimate that this single species of sponge, which comprises only a portion of the benthos, mediates a flux of 444 mg mg C day-1 m-2 from the water column, which places it in the range of shallow-water temperate and boreal systems.

Furthermore, we found that physical disturbance results in changes in community structure. The subtidal rocky coasts near Casey are similar to many of the exposed rocky coasts of the world that support extensive stands of macroalgae that form a strong positive association with understorey encrusting coralline algae. Loss of canopies of algae on temperate coasts often triggers large and predictable changes to the assemblage of understorey taxa. We observed large negative effects of removing canopies of H. grandifolius on encrusting corallines growing beneath, with such effects consistent with predictions of previous research on tropical and temperate coasts. However, elevating concentrations of nutrients did not greatly reduce the magnitude of the negative effects of canopy removal. Nevertheless, our results suggest that disturbance (removal) to canopies of H. grandifolius has large consequences for those organisms associated with this widely distributed (circumpolar) species of canopy-forming algae.

See the full copy of the final report (available for download from the URL given below) for more information.

Also included in the download file, are five Excel spreadsheets. The spreadsheets contain the data collected from the transects, quadrats, etc (see the final report for more information). Where possible the spreadsheets have been converted to csv files.

The fields in this dataset are:

Location

depth

Species

Transect

Quadrat

Irradiance

PAR

Identification info

Alternate title: Cascading effects of global climate change on near shore benthic communities in the Antarctic

Date (Publication): 2007-10-15

Edition: 1

Citation identifier

Dataset DOI

Title: Information and documentation - Digital object identifier system

Date (Publication): 2012-04-23

Citation identifier: ISO 26324:2012

Citation identifier: doi:10.4225/15/5747E5A937DC9

Originator

Pile, A.

Publisher

Australian Antarctic Data Centre

Principal investigator

PILE, ADELE

School Of Biological Sciences

University of Sydney

RM 202A HAYDON-LAURENCE BLDG A08

Sydney

New South Wales

2006

Australia

+61 2 9351 2440

+61 2 9351 2558 (facsimile)

Collaborator

PILE, ADELE

School Of Biological Sciences

University of Sydney

RM 202A HAYDON-LAURENCE BLDG A08

Sydney

New South Wales

2006

Australia

+61 2 9351 2440

+61 2 9351 2558 (facsimile)

Name: CAASM Metadata

Website: https://data.aad.gov.au/metadata/records/ASAC_2300

Status: Completed

Custodian

AU/AADC > Australian Antarctic Data Centre, Australia - AADC, DATA OFFICER (DATA CENTER CONTACT)

Australian Antarctic Division

203 Channel Highway

Kingston

Tasmania

7050

Australia

+61 3 6232 3244

+61 3 6232 3351 (facsimile)

Topic category

Biota
Oceans

Extent

Description: Temporal Coverage

Temporal extent

TimePeriod: 2003-09-30 2005-03-31

Title: The response of encrusting coralline algae to canopy loss: an independent test of predictions on an Antarctic coast.

Date (Publication): 2005

Edition: 144