Open Access

Sponges are one of the major components of benthic communities and are considered to be a key role organism in marine ecosystems. In addition to their importance in terms of biodiversity, sponges are becoming increasingly attractive to the industry, as they themselves or associated symbionts, produce various kinds of secondary metabolites of pharmaceutical properties. Some of them have already been clinically applied. The taxonomic characters of Porifera are limited to only a few morphological and histological characters. In addition, sponges of the same species often show a wide morphological variability, whereas the latter depends on different ecological parameters such as water depth and current conditions. Thus, the taxonomic classification of sponges often becomes a scientific challenge. The fauna of the Yellow Sea rates among the least studied worldwide. At the same time, according to the UN Atlas of the Ocean, the Yellow Sea is one of the most intensively exploited marine areas in the world. This is not least due to the dense human population living in the entire catchment area of the Yellow Sea region. In order to compile medium- and longterm conclusions about the anthropogenic impact on biota of the Yellow Sea, the knowledge of species and their distribution is of crucial importance, as these data form the baseline for all future conservation efforts. Until now the sponge fauna of the Chinese Yellow Sea is insufficiently investigated. Thus, there is only one publication on sponges from this region that has been released hitherto. This paper is dealing with only a view species. However, there is no reference concerning the present location of the voucher material, on which this publication is based on. Consequently, no scientific collection on Porifera from the Chinese part of the Yellow Sea exists to date. In order to compile a documentation of the recent sponge community of the Chinese Yellow Sea, 12 study sites along the coast of the Liaoning Peninsula, China, Northeast Yellow Sea, were investigated with focus on sponge distribution. The corresponding habitats were characterized in regard to their topographical features, abiotic parameters, and common composition of benthic megafaunal and macroalgal assemblages. Due to the lack of comparable studies, a comprehensive literature research on sponges of the shallow Northwest Pacific Ocean was required. As a result the first compilation of publications is presented, dealing with sponges from shallow depths of the northwestern Pacific Ocean. Abstract 2 In the course of this study, 31 sponge species in total were recorded, which are scientifically processed. With the exception of four all specimens were determined to species- level. Twelve out of the total number of species are new to science and are described and classified according to the recent taxonomic system of the phylum Porifera. The results of this study indicate considerable differences in species composition between investigated sites. It is shown that physical factors (particularly current regime, sedimentation, seasonally related variations in temperatures), as well the availability of suitable substrates are directly related to the diversity and abundance of investigated sponge communities. In this context possible adaptation strategies of the corresponding sponges were discussed in detail. Two sponge species, Clathria (Clathria) asodes and Antho (Acarnia) lithophoenix, formerly known exclusively from the northeastern Pacific Ocean, are now recorded from the Northwest Pacific Ocean for the first time. Furthermore, Penares hongdoensis, Clathria (Clathria) hongdoensis and Celtodoryx girardae were synonymized with Penares cortius, Clathria (Clathria) acanthostyli, and Celtodoryx ciocalyptoides respectively. Moreover, the occurrence of eight sponge species, which were known from previous records from the Yellow Sea, could be confirmed. As a result of this study the Asian origin of a sponge species that is invasive to the French and Dutch coasts of the Northeast Atlantic Ocean since the 1990s could be established. Moreover, it is demonstrated that Celtodoryx girardae from the northeastern Atlantic is in fact conspecific with Cornulum ciocalyptoides described by Burton (1935) from the Posiet Bay, Sea of Japan. Apart from taxonomic remarks, variations between populations from both oceans are examined and discussed thoroughly in regard to possible ecological implications. The community of documented sponges shows overlapping with the one from the Sea of Japan. According to the results it is assumed that the endemic degree of the sponges from the Chinese Yellow Sea is rather low to moderate. The material obtained in the course of this study was integrated in the collection of the Senckenbergischen Naturforschenden Sammlungen. Therefore, it is the first scientific collection of sponges from the Chinese Yellow Sea that can be consulted as a basis for all further studies on sponges of this region. The present study is the only investigation of sponges from Dalian and adjacent waters before the spill occurred in the Dalian harbour in July 2010. Therefore, it provides an essential baseline needed to assess the impact of the oil spill on benthic communities.