Green leaves enhance the growth and development of a stream macroinvertebrate shredder when senescent leaves are available

Abstract

1. Freshly fallen green leaves and flowers of terrestrial plants enter temperate streams in spring and summer, when senescent leaf litter is often scarce. These resources appear to provide good supplementary food for macroinvertebrate shredders, but have some potential shortcomings as food or case material for caddisflies. 2. To compare suitability of green leaves or flowers and senescent leaves for the growth and development of stream shredders, we reared the caddisfly Lepidostoma complicatum in the laboratory with treatments that provided larvae with senescent (oak) and green (oak or maple) leaves separately, and also together, in case the combined use of both types of leaf may benefit the shredder. 3. Larvae supplied with green leaves alone grew at 65% of the rate of those provided with senescent leaves alone, due to their lower consumption rate. No individuals given green leaves alone developed into adults, whereas 70% of the individuals given senescent leaves alone did. Green leaves may inhibit larval consumption due to their high phenol content, or they may be unsuitable for case material because they are less tough than senescent leaves. 4. Larvae supplied with both senescent and green leaves (or flowers) had a higher growth rate and developed faster, than those given senescent leaves alone, whereas the proportions of successfully emerged individuals did not differ. Lepidostoma probably benefits from the higher nitrogen content of the green leaves when used together with senescent leaves. 5. These results suggest that green leaves (or flowers) cannot serve as an alternative food resource to senescent leaves, but that they can enhance the growth and development of a Lepidostoma stream shredder if senescent leaves are also available.

Physical factors affecting the distribution of leaf litter patches in streams: comparison of green and senescent leaves in a step-pool streambed

“…In summer, senescent leaves from the previous autumn and current-year green leaves serve as food resources and case material for stream caddisflies (Kochi, 2002;Kochi & Kagaya, 2005). For example, the detritivore Lepidostoma complicatum (Kobayashi), which is often a dominant summer shredder in Japanese headwater streams (Kobayashi & Kagaya, 2002), showed the highest developmental performance when provided with both green and senescent leaves, compared to either green or senescent leaves alone (Kochi & Kagaya, 2005).…”

“…For example, the detritivore Lepidostoma complicatum (Kobayashi), which is often a dominant summer shredder in Japanese headwater streams (Kobayashi & Kagaya, 2002), showed the highest developmental performance when provided with both green and senescent leaves, compared to either green or senescent leaves alone (Kochi & Kagaya, 2005). Senescent leaves may serve as case-building material and green leaves as food.…”

Lateral input of particulate organic matter from bank slopes surpasses direct litter fall in the uppermost reaches of a headwater stream in Hokkaido, Japan

“…In forested headwater streams, considerable amounts of coarse particulate organic matter (CPOM) produced in riparian forests enter stream ecosystems. Such organic matter plays important roles as food and habitat for stream macroinvertebrate communities (Cummins 1973;Anderson and Cummins 1979;Cummins et al 1989;Richardson 1991), case-building material for Trichoptera larvae (Kochi and Kagaya 2005), and direct and indirect food resources for fish (Allan and Castillo 2007). Consequently, such organic matter affects the entire stream ecosystem.…”

Shredder colonization and decomposition of green and senescent leaves during summer in a headwater stream in northern Japan

“…Thus, periods arise during which green (current summer) and senescent (previous autumn) leaves exist alone or simultaneously in streambeds. The trichopteran larva Lepidostoma complicatum (growing in spring and summer) emerged when fed only senescent leaves, but not when fed only green leaves, possibly because larvae that consumed only green leaves were negatively affected by phenol and/or green leaves provided unsuitable case material (Kochi and Kagaya 2005). The former explanation is also applicable to other shredder species that grow in Japan during the spring and summer such as Pseudostenophylax ondakensis (Trichoptera; Kochi 2002), Dicosmoecus jozankeanus (K. Kochi, personal observation), and Sternomoera rhyaca (Amphipoda; Kochi et al 2004).…”