FABREGA-CLIMENT, J*; VENN, C; HRANITZ, JM; Bloomsburg University of Pennsylvania; Bloomsburg University of Pennsylvania; Bloomsburg University of Pennsylvania: Subsurface distribution of the pedunculate barnacle Conchoderma virgatum in the Tropical Pacific

Distribution records indicate that the pedunculate barnacle Conchoderma virgatum is a cosmopolitan species, fouling ships and offshore structures worldwide, that is abundant in tropical waters. We analyzed the distribution of this species on a three-dimensional array of fixed platforms on a basin-wide scale. Barnacles were collected from 34 moorings of the TAO array in 1994 in the tropical Pacific Ocean between 95&degW and 180&deg and from 9&degN to 8&degS, from the surface to a depth of 500 meters. Barnacles were collected from uniformly-sized pods housing temperature sensors that were spaced at intervals to 500 m depth on each mooring and which provided a continuous record of ocean temperature at each depth. Barnacles settling on the temperature pods were almost exclusively the species C. virgatum. The geographic distribution of total C. virgatum per subsurface mooring (from 20 to 500 m) was analyzed by dividing the sampling area into 9 sectors and then comparing the number of barnacles recovered from moorings in each sector. Barnacle abundance varied among sectors (X²=1237.9, df=8, P<0.01), with the greatest number of barnacles in the equatorial and southeastern sectors. Barnacles were not found at depths of 300 meters or greater. Depth of the thermocline was estimated using the depth of the 20&degC isotherm. Abundance of C. virgatum on the temperature pods above and below the maximum thermocline depth was analyzed in each sector. In almost all cases, barnacles were most abundant above the maximum depth of the thermocline (X²=603.4, df=1, P<0.01). Our results indicate that C. virgatum may be cosmopolitan, but has a clumped distribution in the tropical Pacific Ocean.