Spatial niche differentiation of branchiopods (Crustacea: Branchiopoda) and light influence in an ephemeral pool
Date Issued
2010
Date
2010
Author(s)
Wang, Chun-Chieh
Abstract
Siangtian Pond, located in the Yangmingshan National Park, is an ephemeral pool that typically forms after the torrential rains of a typhoon. The inundation period is highly unpredictable, short-lived, and with pronounced variation. Three species of branchiopods inhabit the pool, including Branchinella kugenumaensis, Eulimnadia sp. and Lynceus biformis. This study focused on how the sympatric branchiopods achieved coexistence by reducing the interspecific competition stress. There are two major parts: the first one focused on the distribution patterns of these three branchiopods in the field, and investigated the possibility and mechanism of spatial niche differentiation among them (Chapter Two). The results showed that there was significant separation in spatial distribution in both horizontal and vertical views. Random hot-spotting that changed with time was observed in the horizontal dimension, but relative fixed stratification in the vertical dimension. While fairy shrimp B. kugenumaensis gathered in the superficial layer, clam shrimp L. biformis increased dominance in the bottom layers. The second part explored the influence of light intensity on the spatial distribution of these branchiopod populations (Chapter Three). In addition, we conducted laboratory experiments to clarify their phototaxis reactions. The results demonstrated that both B. kugenumaensis and E. sp. showed significantly positive phototaxis under the laboratory culture setting with illumination ranged from 20 to 22,610 Lux. However, the photo-responses were more complicated when analyzing the branchiopods’ spatial distribution in natural light intensity (ranging from 1,548 to 96,000 Lux). B. kugenumaensis mainly aggregated in higher illuminations, while E. sp. and L. biformis clumped more in lower illuminations. To conclude, we discussed the mechanisms that might result in the spatial distribution of these branchiopods and considered the directions of future studies.
Subjects
SYMPATRIC
BRANCHIOPOD
COMPETITION
DISTRIBUTION
LIGHT
PHOTO-RESPONSE
Type
thesis
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