Consequences of detritus type in an aquatic microsystem: effects on water quality, micro‐organisms and performance of the dominant consumer

Abstract

SUMMARY1. Variation in detritus quality and quantity can have significant effects on aquatic invertebrate food webs. Allochthonous inputs of detritus are the principal energy source for organisms in aquatic tree hole microsystems. We compared the effects of two major detritus types found in tree holes, senescent leaves (Sugar Maple and White Oak) and invertebrate carcasses (dead adult fruit flies and crickets), on several water quality characteristics of laboratory microcosms as well as on mass, survival and population performance of the dominant tree hole consumer, Ochlerotatus triseriatus (Diptera: Culicidae). To date, no study has documented the effects of animal detritus in tree hole microsystems or on resident consumers.2. Aquatic environments receiving invertebrate carcasses had significantly greater total nitrogen, total reactive phosphorus and higher pH, than leaf-based environments. Decay rate of invertebrate carcasses was greater compared to leaf material. Consumption of O 2 by micro-organisms increased with increasing detritus amounts, but we detected no difference between detritus types.3. Ochlerotatus triseriatus larvae grew faster in animal-based treatments, and mean mass of larvae was significantly greater when more animal detritus was used. The effect of animal-based treatments on larvae translated into higher performance for adults, which were three times heavier than counterparts from plant-based containers. Survivorship and estimated population growth rates were significantly greater for O. triseriatus reared on animal-based versus plant-based detritus.4. We hypothesise two mechanisms for the pronounced effect of invertebrate carcasses on mosquito performance relative to that associated with leaf detritus: (i) invertebrate carcasses decompose more quickly and release nutrients more effectively into the aquatic environment; or (ii) O. triseriatus larvae may directly ingest nutrient-rich components of invertebrate carcasses. Because even relatively small animal detritus additions can have strong effects on O. triseriatus populations, studies need to be conducted to explore the overall role of animal detritus in tree holes in nature.

Larval mosquito communities in discarded vehicle tires in a forested and unforested site: detritus type, amount, and water nutrient differences

“…Autumn inputs of senescent leaves, which would have occurred after our sampling had ended, would have caused our tires in the forested site to receive substantial inputs of leaves and other plant-derived detritus. Animal detritus, which has been shown to provide greater nutrition to container mosquito larvae (Yee and Juliano 2006), and which attracts more species and individuals to container habitats (Yee and Juliano 2007), did not differ between sites on any date (Table 1). Because animal detritus decomposes at a faster rate than plant-derived detritus (Yee and Juliano 2006), and because of the relatively long time between our surveys, additions of animal detritus to these tires may be underestimated.…”

“…The relatively high levels of TP relative to TN encountered in these tires suggests nitrogen limitation. Addition of detritus-derived nitrogen has been shown to be important for mosquito growth (Carpenter 1982,Walker et al 1991,Kaufman et al 2002,Yee and Juliano 2006. Besides nitrogen, labile carbon is much more likely to limit production of basal microbial food resources than is phosphorous in some mosquito systems (Kaufman et al 2002,Kaufman and.…”

“…Thus, these data suggest that some of the variation in mosquito populations between sites may be attributable to variation in detritus inputs into tires. Tree holes represent another mosquito-dominated aquatic system that is based on allochthonous inputs of terrestrial detritus (Daugherty et al 2000, Kitching 2001, Yee 2006, and where inputs of detritus type and amount affect community and populations of invertebrates (Jenkins et al 1992, Srivastava and Lawton 1998, Yee and Juliano 2007.…”

“…Conductivity values were obtained using a Cole-Parmer conductivity meter. These nutrients have been shown to be related to the size or performance of populations of container mosquitoes (Beier et al 1983, Yee and Juliano 2006, Yee and Juliano 2006, 2007. On 27 July and 5 September we also removed an additional 100 ml sample for quantification of water-column algae via measurements of chlorophyll a (mg m −3 ).…”

“…Growth and survival of container mosquitoes are affected by detritus type and dissolved nutrients (e.g., Walker et al 1997, Léonard and Juliano 1995, Paradise and Dunson 1997, Yee and Juliano 2006. Although detritus inputs and their effect on mosquitoes in tree holes have been investigated (e.g., Lounibos et al 1993, Léonard and Juliano 1995, Walker et al 1997 ), little is known about detrital inputs into discarded vehicle tires, how such inputs affect populations and communities of invertebrate, or species interactions that may shape these communities.…”