Spatial and temporal variation in invertebrate consumer diets in forested and herbaceous wetlands

Abstract

Macroinvertebrates have important functional roles in wetland ecosystems, but these roles are not always well understood. This study assessed which foods invertebrate consumers assimilate within a set of wetland habitats. During 2006 and 2007, non-Tanypodinae chironomid larvae and select crustaceans (Crangonyx amphipods, Caecidotea isopods, Simocephalus cladocerans) were sampled, along with their potential food sources, from forested and herbaceous areas in wetland habitats (depression, floodplain, swamp complex) across the southeastern U.S.A. Invertebrate and food source samples were processed for carbon and nitrogen isotope signatures. These data were analyzed with the U.S. Environmental Protection Agency's IsoSource mixing model, to estimate the potential relative contributions of different food items and to highlight both important and unlikely food sources. In the forested habitats, litter from trees (leaves, wood, fruit), epiphyton, detrital FPOM (fine particulate organic matter), sediment, and macrophyte litter were found to be major foods for midges and crustaceans, although considerable spatial and temporal variation existed in consumption. In the herbaceous habitats, algae (epiphyton, periphyton, metaphyton, phytoplankton), sediment, and macrophyte litter were important food resources. Comparisons between forested and herbaceous wetlands suggested that algal resources were widely consumed by midges and crustaceans, and that detrital sources were also important in forested wetlands.

Advies inrichting en beheer beekdal Geeserstroom

“…Herbivorie speelt een onderschikte rol, en beperkt zich vooral tot het afgrazen van algen door bijvoorbeeld slakken (Taylor & Batzer 2010). Voor detritivore ongewervelden, zoals miljoenpoten, (water)pissebedden, kokerjuffers en kevers, is met name de hoeveelheid en samenstelling van het strooisel (o.a.…”

Potential influence of water level changes on energy flows in a lake food web

“…influence of migration or sexual maturity on feeding behavior) is decisive in the passage of energy sources through the food web [6,14,19,46]. The relative availability of autochthonous and/ or allochthonous resources in food webs shifts with gradients of water depth, nutrient concentrations, degree of canopy cover and distance from terrestrial habitats [9,14,17,21]. Freshwater macrobenthos and fish assemblages were based on the productivity of basal food sources [8,10,18].…”

“…Advances in isotopic mixing models provide opportunities to use both 13 C and 15 N to quantify the contributions of different sources to consumers. For example, studies of streams and floodplains [8,9,14], estuaries [13,[17][18][19], and wetlands [20,21] have used stable isotope analyses to estimate the relative importance of autochthonous and allochthonous production for aquatic food webs and their temporal variations. However, fluctuations in lake water levels and their interactions with food web dynamics has received limited attention [5,6].…”

Litter decomposition in created and reference wetlands in West Virginia, USA

“…It is linked to wetland functions including nutrient availability and cycling (Facelli and Pickett 1991;Allison and Vitousek 2004), primary productivity (Brinson et al 1981;Xiong and Nilsson 1999), and seed germination (Xiong and Nilsson 1997;Taylor and Middleton 2004) through the breakdown and release of nutrients from plant litter. Decomposition is linked to wetland services such as invertebrate and wildlife habitat through primary production and detritus availability (Burdett and Watts 2009;Taylor and Batzer 2010), to carbon storage through organic matter accumulation (Bridgham et al 2006), to sediment and mineral retention through primary productivity and organic matter accumulation (Braskerud 2000, Rooth et al 2003 and to stream nutrient availability through nutrient cycling (Richardson 1994;Mitsch and Gosselink 2007). It is this web of interactions that allows decomposition rate to influence a wetland's functions and services and which makes it a potential tool for assessing the evolution of overall ecosystem function (Spieles and Mora 2007).…”