Scale effect of spatial pattern for Antarctic krill (Euphausia superba) distribution around Antarctic Peninsula based on changepoint analysis

As a key species in the Antarctic ecosystem, distribution of Antarctic krill (Euphausia superba) resources demonstrates significant spatial-temporal heterogeneity. Different spatial scales may give different results when analyzing the spatial pattern of Antarctic krill. In order to analyze the influence of different spatial scales on the spatial pattern of Antarctic krill, based on the biomass data of Antarctic krill in the waters near the Antarctic Peninsula from 1996 to 2011, Moran’s I, Geary’s C and Ripley's K value were calculated to analyze the spatial pattern of Antarctic krill resources, and to detect changepoints of various spatial indicators at different spatial scales. The results showed that the value of global Moran’s I decreased as the increasing of spatial scales, the value of Geary’s C increased but then decreased. The results of the generalized estimation equation showed that both spatial scale and distance had a significant impact on the K′ value. In general, Antarctic krill around the Antarctic Peninsula had a high-density cluster distribution. and the aggregation degree of Antarctic krill around Antarctic Peninsula decreased with the increasing of the spatial scales. The changepoint detection showed that 25'×25' was the spatial scale where multiple spatial indicators qualitative change. Therefore, this study suggests 25'×25' can be considered as the scale threshold for comparing the results of such studies within the scale of 1′×1′~60′×60′. This study explored the scale effect of the spatial distribution of Antarctic krill resources, which can provide a scientific basis for further research on the spatial and temporal distribution of local krill resources and the formation mechanism of fishing grounds.