平底海星(Asterias amurensis)(北太平洋海星) 能在新领域建立庞大的族群。在港口菲利普海湾 (它们第一次被发现的地方) 做的估计，指出在两年内增加高达一千二百万个体。在他们的原产地中，已知他们会周期性地「破灭与繁荣」，达到高丰富度后族群会迅速的下降。(NSW, 2007)
北太平洋海星是一个杂食性捕食者，偏爱贻贝、扇贝与蛤。它几乎吃任何东西它能发现的东西，包括死的鱼与鱼的废弃物.(CSIRO, 2004) 一般认为海星是原生海洋生物的严重害虫。它与极度濒危的斑点棘茄鱼的族群下降有关 (请参阅Brachionichthys hirsutus在 IUCN 红皮书 ) 在塔斯梅尼亚，它吃棘茄鱼的卵团，与/或吃海椿象(海鞘类)，棘茄鱼会把卵产在海椿象上面。(NSW, 2007) 海星也被认为是一个海洋生物养殖业的有害生物，会吸附在扇贝延绳钓、贝卵袋子，贻贝与牡蛎线和鲑鱼笼。(CSIRO, 2004) 在塔斯梅尼亚东南方，一些生产牡蛎的海水养殖场，已经受到海星影响。(NSW, 2007)
在日本，海星族群爆发，使海洋生物养殖业损失数百万元。(NSW, 2007; NIMPIS, 2002)
Derwent Estuary (Australia) (Australia)
改变自然底栖生物群落: The results of an experimental study (Ross et al. 2002) indicate that Asterias amurensis can have a large impact on the survival of juvenile bivalves; effectively arresting mass settlement events. An earlier study (Ross 2001) demonstrated the impact of the seastar on adult bivalve populations, particularly the commercial bivalves Fulvia
tenuicostata and Katelysia rhytiphora. Ross et al. (2002) suggest that these combined results indicate that the seastar is "largely responsible for the decline and subsequent rarity of adult bivalves in the Derwent Estuary".
竞争: The northern Pacific seastar has, since its arrival, become the dominant benthic invertebrate predator in the Derwent Estuary. The native invertebrate predator, the seastar Coscinasterias muricata which is present in the estuary, is unable to attain the densities of the northern seastar and maintain the densities over large areas and long periods. A. amurensis is considered to be a major threat to native assemblages. There are grave concerns of the dispersal of the seastar larvae to areas outside the estuary. The highest concentrations of seastar larvae have been recorded adjacent to the port areas in the estuary (Ross et al 2003).