Trophic model of the subtropical headwater stream habitat of Formosan landlocked salmon Oncorhynchus formosanus 

Abstract

Using the Ecopath approach and a network analysis, a mass-balance trophic model was constructed to analyze the structure and energy flows of a high-altitude subtropical headwater stream, Chichiawan Stream, the only habitat of the Critically Endangered Formosan landlocked salmon Oncorhynchus formosanus. Natural abundances of carbon and nitrogen isotopes (δ 13 C and δ 15 N) were used as a complementary method to stomach content analysis to trace food sources of consumers in the stream. Riparian C 3 plants were the major food source of dominant gatherer and filterer aquatic insects, while diatoms were the major food source of scraper aquatic insects. Lindeman trophic analysis indicated that the flows of detritivory and herbivory were quantitatively equally important as food sources for consumers in the stream, suggesting a close terrestrial−aquatic linkage. The trophic model of Chichiawan Stream comprised 13 compartments and 4 integer trophic levels with the highest trophic level of 3.12 for birds. The pedigree index for the trophic model was 0.71, indicating a high-quality model. The mixed trophic impacts indicated that the biomass of Formosan salmon was unlikely constrained by food sources or predation pressure by birds. In a comparative analysis with other trophic models of temperate mountain streams, the total consumer biomass and mean trophic transfer efficiency were relatively low in this subtropical mountain stream, which is characterized by high precipitation, steep channels, rapid current velocity, and changing flow regime. To conserve the Formosan salmon, the first priorities are agricultural runoff control and maintaining a well-vegetated riparian zone.

Does <i>Culicoides</i> spp. (Diptera: Ceratopogonidae) Not Suck Human Blood in Riparian Habitat of a National Park

“…The original long term ecological research in Wuling area is a bimonthly investigation, from 7:30 to 19:30, we set up and retreat multiple ecological collecting traps [7] of the study area is situated at 24˚23'N, 121˚18'E and denoted both in Figure 1 and in the text as well according to our previous work [8].…”

Trans-Disciplinary Education for Sustainable Marine and Coastal Management: A Case Study in Taiwan

“…Such changes are a threat to national security, the livelihood of residents, tourism and sightseeing, ecosystem preservation and sustainable development of fishery [35]. In addition, warm water temperatures related to climate change is well documented to increase the rate of coral bleaching [36].…”

Dietary variation and food selection by mayfly grazers in a subtropical mountain stream

“…Due to the Formosan salmon's critically endangered status (Chung et al 2008), there is an urgent need to identify the energy sources supporting the stream food web. Lin et al (2012) identified mayfly grazers as an important food source for the Formosan salmon in the stream. Nevertheless, the diet of mayfly grazers in the Chichiawan Stream is still unclear.…”

“…Autochthonous algae may be more important than allochthonous organic matters to stream consumers in tropical forested headwater streams (March and Pringle 2003). An open forest canopy can lead to autochthonous algae becoming the dominant food source for herbivores in rainforest streams (Brito et al 2006) and tropical Asia (Salas and Dudgeon 2001;Mantel et al 2004;Yam and Dudgeon 2005;Lin et al 2012). Autochthonous algae are the main energy source in some shaded tropical headwater streams (Mantel et al 2004;Lau et al 2008;2009;Li and Dudgeon 2008).…”