Niche partitioning of fish assemblages in a mountain stream with frequent natural disturbances – an examination of microhabitat in riffle areas

Abstract

Microhabitat usage by different species of fish was studied to examine the potential for niche partitioning in riffle areas of a mountain river characterised by frequent natural disturbances. We randomly sampled 96 riffle-area plots (mostly 1 m · 1 m) in a stream in south-western Taiwan for fish abundance and microhabitat characteristics during the dry season from November 2008 to March 2009. Density and electivity values associated with microhabitat usage indicate the presence of niche partitioning among four major species of fish based largely on flow velocity and water depth. Hemimyzon formosanum, a herbivore, prefers higher velocity and shallower water but avoids sandy substrate. Onychostoma alticorpus, a herbivore, prefers lower velocity and deeper water. Rhinogobius nantaiensis, an omnivore, prefers higher velocity, shallower water and gravel-sized substrate but avoids boulder substrate. Acrossocheilus paradoxus, an omnivore, prefers lower velocity and deeper water but avoids pebble-sized substrate. The existence of differentiation of microhabitat preference and overlap of microhabitat usage suggests that interspecific competition is a factor affecting the structure of this fish assemblage, which may remain at early successional stages because of frequent disturbances in the stream. Study results also show that density and electivity detect preference differently. Density detects microhabitat preference for two herbivores while electivity detects microhabitat preference for two omnivores.

The Importance of Providing Multiple-Channel Sections in Dredging Activities to Improve Fish Habitat Environments

“…A. paradoxus and O. alticorpus are less rheophilous fish species that they prefer deeper water, and H. formosanus and R. nantaiensis are the more rheophilous fish species that they are prefer shallow water [51]. In our study, the mean water depths were 33.4 cm and 26.6 cm in the main channel and secondary channel, respectively ( Table 2).…”

“…Flow velocity and salinity affected distribution of A. paradoxus and R. nantaiensis whereas salinity had a low CV. A. paradoxus prefers slower-moving water [51], so it was difficult to catch A. paradoxus in the main channel. However, R. nantaiensis prefers fast-moving water [51].…”

“…A. paradoxus prefers slower-moving water [51], so it was difficult to catch A. paradoxus in the main channel. However, R. nantaiensis prefers fast-moving water [51]. Our reason for drawing this conclusion is that R. nantaiensis is a small-sized fish species so the body of the adults and young fish are very similar.…”

“…This indirectly suggests that no environmental factors significantly affect the distribution of fish species in the single-channel sections, as compared to the multiple-channel sections. Four fish species eat algae [51], but chlorophyll a could have a great deal of influence on A. paradoxus and R. nantaiensis in the main channel and on R. nantaiensis in the single-channel sections. The food of A. paradoxus and R. nantaiensis includes algae, small fish and invertebrates [52].…”

Application of the physical habitat simulation for fish species to assess environmental flows in an Atlantic Forest Stream in South-eastern Brazil

“…According to Wootton (1998) heterogeneous systems supply a large variety of microhabitats with sites where fish species can shelter against predators and find a wide variety of feeding resources and places for reproduction. Recently, some studies using habitat simulation models have reinforced that physical habitat variables and cover availability determine patterns of habitat use in rivers and streams (Lee & Suen, 2012;Costa et al, 2012;Teresa & Casatti, 2013;Costa et al, 2013). However, the capability of prediction of these models depends on the understanding of how the species respond to environmental gradient conditions.…”