We present 1.4 and 2.5 GHz Australia Telescope Compact Array ( ATCA ) observations of the galaxy cluster A3158 ( z=0.0597 ) which is located within the central part of the Horologium-Reticulum Supercluster ( HRS ) .
Spectroscopic data for the central part of the HRS suggest that A3158 is in a dynamically important position within the supercluster and that it is moving toward the double cluster system A3125/A3128 which marks the centre of the HRS .
A total of 110 radio galaxies are detected in a 35 arcminute radius about the cluster at 1.4 GHz , of which 30 are also detected at 2.5GHz .
We examine the source counts and compute the Radio Luminosity Function ( RLF ) at 1.4 GHz from the subset of 88 sources found within the full-width half-power area of the ATCA beam .
Comparison of the source counts in the area over the background , as computed by Prandoni et al .
( 2001 ) , shows some evidence of an excess of galaxies with L _ { 1.4 GHz } \leq 2 \times 10 ^ { 22 } WHz ^ { -1 } .
This result seems to indicate a star forming population and is a result similar to that found recently by Owen et al .
( 2005 ) for the merging cluster A2125 .
In addition we find that the radio luminosity function for early-type galaxies ( E and S0 ) below log P _ { 1.4 } \sim 22.5 is lower than that found for a composite cluster environment ( Ledlow & Owen , 1996 ) but is similar to the early-type RLF for clusters in the centre of the Shapley Super cluster ( Venturi et al .
2000 ) which are believed to be in the latter stages of merging .
This result implies that the cores of superclusters are environments where radio emission , particularly resultant from AGN , is suppressed in the later stages of merging .
Thus , radio observations of clusters might be sensitive indicators of the precise merger stage of the cluster but more observational evidence is still required to establish this trend .