The late Holocene demise of a sublittoral oyster bed in the North Sea

A fossil oyster bed (Ostrea edulis) was recently encountered offshore Helgoland (German Bight). Oysters are important filter feeders in marine environments and their habitat structure supports a large associated biodiversity. The European flat oyster Ostrea edulis has historically occurred in vast populations in the North Sea, but declined massively in the early 20th century. The ecological restoration of Ostrea habitats is a current focal point in the North Sea. To better understand the mechanisms that caused the local collapse of the oyster population, this study investigated the size structure, weight, and age of the shells, along with the spatial dimensions, seafloor properties, and environmental context of the oyster bed. The results show that the demise of the population occurred around 700 CE, ruling out excessive harvest as a driver of decline. Synchronicity of increased geomorphological activity of rivers and concurrent major land use changes in early medieval Europe suggest that increased sedimentation was a viable stressor that reduced the performance of the oysters. The shells provided no indication of a demographically poor state of the oyster bed prior to its demise, but manifested evidence of the wide-spread occurrence of the boring sponge Cliona sp. Our study challenges the assumption of a stable preindustrial state of the European flat oyster in the North Sea, and we conclude that the long-term variability of environmental conditions needs to be addressed to benchmark success criteria for the restoration of O. edulis.

The relationship between fish abundance and benthic community structure on artificial reefs in the Mid-Atlantic Bight, and the importance of sea whip corals Leptogorgia virgulata

Autogenic engineers (i.e., biogenic structure) add to habitat complexity by altering the environment by their own physical structures. The presence of autogenic engineers is correlated with increases in species abundance and biodiversity. Biogenic structural communities off the coast of Delaware, Maryland, and Virginia (Delmarva) are comprised of multiple species including boring sponge Cliona celata, various hydroids (i.e., Tubularia sp., Obelia sp., Campanular sp.), northern stone coral Astrangia poculata, sea whips Leptogorgia virgulata, and blue mussels Mytilus edulis. Sea whips are soft corals that provide the majority of vertical height to benthic structure off the coast of the Delmarva peninsula. The mid-Atlantic bight is inhabited by several economically valuable fishes; however, data regarding habitat composition, habitat quality, and fish abundance are scarce. We collected quadrat and sea whip images from 12 artificial reef sites (i.e., shipwrecks) ranging from 10 to 24 m depth to determine proportional coverage of biogenic structures and to assess habitat health, respectively. Underwater video surveys were used to estimate fish abundances on the 12 study sites and determine if fish abundance was related to biogenic coverage and habitat health. Our results showed that higher fish abundance was significantly correlated with higher proportional sea whip coral coverage, but showed no significant relationship to other biogenic structure. Assessment of sea whip condition (as a damage index) showed that sea whip corals on artificial reefs off the Delmarva coast exhibited minor signs of degradation that did not differ significantly among study sites.

Relationships between boring sponge assemblages and the availability of dead coral substrate on Mexican Pacific coral reefs

Boring sponges are an important component of bioeroder assemblages in tropical coral reefs. They are considered as a potential threat for coral reef health, and the increase of dead corals is expected to promote their abundance. The relationship between the availability of dead coral substrata and the development of boring sponge assemblages was evaluated during El Niño 2015–16 at five reefs from Zihuatanejo, Guerrero, Mexico. Environment and substrate quality were assessed. Overall, environment conditions remained normal in relation to previous studies in the area. Only water temperature showed unusually high records at all sites and coincided with bleaching and mortality of corals, possibly caused by the effects of the El Niño event. Abundance of boring sponges in dead corals and coral rubble was lower than during previous studies. Although sponge abundance was not directly related to cover of both dead corals and coral rubble, cover of dead corals showed a high correlation with the variation in the structure of sponge assemblages across sites.Cliona vermiferadominated sponge assemblages at all sites, and its abundance was high under conditions of high cover of live corals and low cover of bleached corals. Since overall sponge abundance responded in a similar way, these results suggest that boring sponge assemblages dominated byC. vermiferaare enhanced by conditions favourable for corals. Our results imply that El Niño events in the Mexican Pacific are not likely to cause immediate population outbreaks of boring sponges.

Potensi antitumor dari beberapa spons laut asal teluk Manado

Screening of antitumor for the extract and fraction from the marine sponges ofManado Gulf, Aaptos sp., Acervochalina sp., Gelliodes sp., Theonella sp., and orangeboring sponge have been done by use P388 murine leukemia cell. Activity test resultshowed IC50 of the extract and fraction from Aaptos sp were: MeOH extract 5938ng/mL and BuOH extract 125000 ng/mL; Acervochalina sp: EtOH extract 125000ng/mL, PE extract 125000 ng/mL, EtOAc extract 4251 ng/mL, BuOH extract125000 ng/mL; Gelliodes sp: EtOH extract 125000 ng/mL; Theonella sp: EtOHextract 125000 ng/mL, PE extract 9282 ng/mL, EtOAc extract 3273 ng/mL, BuOHextract 125000 ng/mL; orange boring sponge: MeOH extract 1422 ng/mL. Based onthe IC50 value, it could be concluded that MeOH extract of Aaptos sp., EtOAc extractof boring sponge could be a sources for cytotoxic compounds.

Excavating sponges from the Adriatic Sea: description ofCliona adriaticasp. nov. (Demospongiae: Clionaidae) and estimation of its boring activity

Boring sponge diversity in the area of the Conero Promontory, the most important rocky emergence on the west coast of the Adriatic Sea (Italy), was assessed. Four species were recorded; one of them,Cliona adriatica, is new and is described here. The new species differs from all the other excavating sponge species, characterized by yellow papillae and lacking or scarcity of microscleres, in the large size of the boring chambers and the presence of numerous styles.Cliona adriaticais present on about 12% of the surface of rocky bottoms in the Conero Promontory area. The impact of this highly destructive species on the carbonatic micritic rock of the promontory was evaluated calculating a relationship between the volume of the boring chambers and the surface of the epilithic portions. Consequently, it was estimated that 1 cm2of epilithic tissue corresponds to 8.5 g of excavated rock. The recorded correlation between the excavated volume and the area of the papillar zone (roughly the area of the substratum affected by the erosion) allows an estimation of the substratum removed by a boring sponge, using only visually oriented, non-destructive, sampling methods.

Pione angelae sp. nov. (Porifera: Hadromerida: Clionaidae) a new species of boring sponge inhabiting pagurized shells from the south-western Atlantic

A new species of the clionaid genus Pione is described from the south-western Atlantic in Argentine waters. Pione angelae sp. nov. is the first record of the genus from southern South America. It occurs on shells of Olivancillaria urceus and Buccinanops monilifer, two common gastropods living off Mar del Plata, Buenos Aires, Argentina (38°01′41″S 57°31′07″W) that are inhabited by the hermit crab Loxopagurus loxochelis. Pione angelae sp. nov. is visible on the shell surfaces as circular papillar perforations of 312 μm on average with regular diameters. They lead directly into interconnected chambers from both sides of the shell. The chambers form well-defined galleries in dense substratum. Straight tylostyles in two size-classes (defined by their length: width ratio) occur: 158.6 μm length×2.1 μm width and 185.0×4.5 μm, with spherical heads. Microscleres are more common than tylostyles, with microspined acanthoxeas of 91 μm length, slightly bent in the centre, as well as spirasters of 12 μm length with spines more concentrated on the crests of the spirals; rarely they are straight (microrhabd like). The present samples are compared to similar valid species of the same genus and it is concluded that they represent a new species.