Characteristic spatial scale of distribution for Antarctic krill (Euphausia superba) density in the Antarctic Peninsula

Distribution pattern of living resources is spatial scale-dependence, therefore an inappropriate scale may produce misleading results. As a key species in the Antarctic ecosystem, distribution of Antarctic krill (Euphausia superba) demonstrates significant spatial-temporal heterogeneity. The distribution pattern of this species is spatiotemporal complex and cannot be predicted effectively. In order to understand the spatial-temporal distribution pattern of krill resource in the Antarctic Peninsula, an important ecological and commercial-interested regions, the Moran's I value of krill density distribution was calculated at 12 spatial scales (5'×5' - 60'×60') by 5' grid of latitude and longitude. The results showed that the spatial pattern of krill is differed in spatial scales. The distribution of krill density showed a discrete trend at the 25'×25' scale, but the distribution of krill density showed a clustering trend at the other 11 spatial scales. According to the correlogram between the Moran's I value and spatial scale, the characteristic spatial scales of krill density distribution were determined as about 25'×25', which was determined by the Moran's I value inter-crossing the x-axis for the first time, and 15'×15', which was determined by the smallest scale with no significant difference between the Moran's I value and zero in the correlogram, respectively. This study showed that the method with no significant difference between the Moran's I value and zero value was more consistent with the characteristics of krill resource. It was, therefore, recommended that 15'×15' could be the optimum spatial scale for analyzing the distribution of krill density in this region.