Does the native predator Trophon geversianus exert top-down control on the invasive barnacle Balanus glandula on Patagonian rocky shores?

2019 ◽  
Vol 70 (11) ◽  
pp. 1552
Author(s):  
María José Pio ◽  
María M. Mendez ◽  
David E. Galván ◽  
Gregorio Bigatti ◽  
Kaydee West ◽  
...  

Trophic interactions between the native gastropod predator Trophon geversianus and the invasive barnacle Balanus glandula may have facilitated the successful expansion of the barnacle along rocky intertidal coastlines in Argentina. In this study, through field observations and a stable isotope reconstruction of the diet of T. geversianus, we assessed whether and how frequently this drilling muricid gastropod consumes the invasive B. glandula on a Patagonian rocky shore. Field observations indicated that B. glandula and T. geversianus co-occur in the middle intertidal. Feeding observations and stable carbon and nitrogen isotope dietary reconstructions showed that T. geversianus readily and successfully consumes B. glandula, but at low rates (4% of diet) relative to native mussel prey, which compete with B. glandula for space. This study shows that T. geversianus exerts little top-down control on this invasive barnacle on Patagonian rocky shores. The success of B. glandula on these shores is plausibly enhanced directly by this weak interaction and indirectly by the preference of T. geversianus for native prey rather than the absence of predators or invader immunity from predation. The results of this study complement previous studies that have shown that tolerance to extreme desiccation stress in harsh intertidal environments is crucial for the establishment of B. glandula.

Author(s):  
Xuan Lu ◽  
Fengxia Zhou ◽  
Fajin Chen ◽  
Qibin Lao ◽  
Qingmei Zhu ◽  
...  

Elemental (total organic carbon (TOC) and total nitrogen (TN)) and stable carbon and nitrogen isotope compositions (δ13C and δ15N, respectively) in the surface sediment of Zhanjiang Bay (ZJB) in spring and summer were measured to study the spatial and seasonal changes of organic matter (OM) and assess the human-induced and environment-induced changes in the area. The OM in the surface sediment of ZJB was a mixture of terrestrial and marine sources, and was dominated by marine OM (54.9% ± 15.2%). Compared to the central ZJB, the channel and coastal ZJB areas had higher δ13C and δ15N values, higher TOC and TN concentrations, and lower TOC/TN ratios, indicating higher primary productivity and higher percentages of marine OM in the latter two subregions. Mariculture activities, sewage inputs, and dredging were responsible for these phenomena. Clear seasonal variations in OM were observed in ZJB. The average proportions of terrestrial OM in summer increased by 10.2% in the ZJB channel and 26.0% in the coastal ZJB area compared with those in spring. Heavy rainfall brought a large amount of terrestrial OM into the channel and coastal ZJB areas, leading to the increase of the terrestrial OM fraction in these two subregions in summer. In summary, anthropogenic influences had a significant influence on the spatial and seasonal variations of sedimentary OM in ZJB.


2019 ◽  
Vol 33 (9) ◽  
pp. 831-838 ◽  
Author(s):  
Michael A. Schillaci ◽  
Jessica Lintlop ◽  
Monika Sumra ◽  
Mark Pizarro ◽  
Lisa Jones‐Engel

2019 ◽  
Vol 105 ◽  
pp. 59-69 ◽  
Author(s):  
Ana Curto ◽  
Patrick Mahoney ◽  
Anne-France Maurer ◽  
Cristina Barrocas-Dias ◽  
Teresa Fernandes ◽  
...  

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