Food sources of dominant macrozoobenthos between native and non-native mangrove forests: A comparative study

Abstract

The macrozoobenthos is an important link of the food web in coastal wetlands. Diet-habitat relationships may significantly depend on qualitative differences and seasonal availability of food sources. Increasing interest has been shown in food web structure altered by non-native plants. In particular, however, a non-native mangrove species from Bangladesh, Sonneratia apetala, has been widely planted in China, but little is known about its possible impact on food sources of macrozoobenthos living in these non-native mangrove forests. Therefore, in this study, we used fatty acid analysis to compare the food sources of one littorinid snail and two grapsid crab species between two native mangrove forests and one non-native S. apetala plantation in the Zhanjiang Mangrove National Nature Reserve of China. We found that the sediment of all three forests had high diatom and bacteria signals, but low mangrove leaf signals, while the opposite patterns were detected in the three macrozoobenthos. Specifically, the gastropod Littoraria melanostoma relied mainly on mangrove leaves and brown algae as food sources, with significant differences among the three mangrove forests, and showed significant seasonal variation in its diet. The grapsidae species (Perisesarma bidens and Parasesarma plicatum) mainly grazed on mangrove litter, brown and green algae, and occasionally consumed diatoms and bacteria, also showing significant seasonal variation in their diet. Overall, Principle Components Analysis (PCA) of the fatty acid profiles showed a significant overlapping in food sources among the macrozoobenthos living in the non-native and native mangrove forests, but significant seasonal variations in their food sources. This suggests that the planting of non-native S. apetala near original mangrove forests has had little effect on the feeding behavior of macrozoobenthos some 10 years after planting.