Chironomus species (Diptera: Chironomidae) in the profundal benthos of Spanish reservoirs and lakes: factors affecting distribution patterns

Abstract

SUMMARY The taxonomy, distribution and habitat preferences of Chironomus larvae from profundal benthos of reservoirs and natural lakes in Spain are presented. The 114 water bodies studied were medium to large reservoirs and lakes throughout Spain, and were visited on at least two occasions (summer and winter). Out of the natural lakes investigated, Chironomus larvae were found only in one karstic lake (Banyoles), and to date, these have not been found in the high mountain lakes of the Spanish Pyrenees or Sierra Nevada, or in Spain's largest oligotrophic lake (Sanabria). Multiple regression with environmental data from reservoirs showed that the density of Chironomus larvae was inversely correlated with water depth, temperature and sulphide content of the bottom water, but positively correlated with alkalinity and particulate organic nitrogen (PON) content of bottom water. Thus, the density of Chironomus larvae was higher in shallow reservoirs from the eastern part of Spain (calcareous water and higher PON), but markedly lower in southern reservoirs (higher temperature and higher sulphide). According to morphological and cytological characteristics, three species of this genus have been identified in the samples examined: C. bernensis, C. plumosus and C. nuditarsis. Reasons for the absence of other widespread European species are discussed. Using canonical correspondence analysis to relate species and environmental variables, C. bernensis showed a significant preference for reservoirs with higher oxygen concentrations in bottom water and lower total reactive phosphorus (TRP) content at the surface than those reservoirs where C. plumosus‐type were found. This suggests that the smaller C. bernensis prefers mesotrophic reservoirs and the larger C. plumosus‐type (C. plumosus + C. nuditarsis) prefers eutrophic reservoirs. Taking into account the TRP/depth index for those samples collected at depths below the thermocline, and thus, where oxygen can be a limiting factor, C. bernensis and C. nuditarsis were present in reservoirs in which the index was low (< 1:170 for C. bernensis and >1:800 for C. nuditarsis), while C. plumosus thrived in reservoirs with higher index values (<1:20). These differences may reflect the preference of C. bernensis and C. nuditarsis for detrital material, while C. plumosus prefers phytoplankton. These observations are in agreement with the depth distribution of each species: C. plumosus was restricted to reservoirs less than 46 m deep, whereas the other two species (i.e. C. bernensis and C. nuditarsis) were found up to depths of 65 and 80 m, respectively. Data from a transect (5–20 m deep) in Lake Banyoles are consistent with the general pattern described in reservoirs. In this lake, a high density of C. bernensis was recorded from littoral and sublittoral areas with abundant oxygen (above or close to the thermocline), whereas C. plumosus was scarce in several parts of the lake, especially in oxygen‐deficient areas during the summer. This karstic, oligotrophic lake has a low TRP/depth index,...

Benthic macroinvertebrates of a tropical lake: Lake Caçó, MA, Brazil

“…Benthic organisms actively participate in the energy flow and nutrient cycles within aquatic ecosystems, having a major role in the exchange of phosphorus and nitrogen between the sediment and the water (Gardner et al, 1983;Fukuhara and Sakamoto, 1988;Leal et al, 2003, Pelegri and Blackburn, 1996, Real et al, 2000. By constantly turning the sediment, through their digging and tunnelling activity, and by breaking down the solid organic matter that settles there, these organisms reduce the size of particles and this contributes to the liberation of nutrients trapped in the sediment, into the water column (Marques et al, 1999;Callisto and Esteves, 1998).…”

“…By constantly turning the sediment, through their digging and tunnelling activity, and by breaking down the solid organic matter that settles there, these organisms reduce the size of particles and this contributes to the liberation of nutrients trapped in the sediment, into the water column (Marques et al, 1999;Callisto and Esteves, 1998). They also form part of the food chain of diverse important aquatic animals, notably fish (Margalef, 1983) and have a relevant role in the recovery of organic matter and nutrients for the water column by bioturbation activity (Real et al, 2000;Leal et al, 2003;Caliman et al, 2007;Callisto et al, 2009).…”

Bathymetric distribution of benthic macroinvertebrates in deep lake Motosu, Fuji Five Lakes, Japan

“…Numerous studies have been conducted regarding the distribution and abundance of benthic macroinvertebrate populations in relation to various environmental factors (reviewed by Brinkhurst 1974;Real et al 2000). The hypolimnion oxygen concentration, food quality and quantity, and water temperature are the main factors influencing the presence and biomass of benthic communities, i.e.…”

“…chironomid larvae and oligochaetes, in lakes and reservoirs (reviewed by Oliver 1971;Jonasson 1996). Thus, benthic macroinvertebrates have been used as indicators of bottom environmental conditions in lakes and reservoirs (Berg et al 1962;Real et al 2000). According to Lindegaard (1995), chironomid larvae can provide much information about lake classification and water quality assessment.…”

The importance of sedimenting organic matter, relative to oxygen and temperature, in structuring lake profundal macroinvertebrate assemblages

“…Thienemann (1922) and Brundin (1951) were the first to show empirically that hypolimnetic oxygen is pivotal in structuring profundal communities. This has remained a central tenet of profundal macroinvertebrate ecology (Int Panis et al, 1996;Real et al, 2000;Verneaux et al, 2004). Appreciation of the role of phosphorus as a main driver of lake productivity and trophic state (Vollenweider, 1968;Schindler, 1974) enabled a more comprehensive understanding of pelagic-benthic coupling: anthropogenic nutrient enrichment accelerates lentic algal productivity and profundal fauna respond to the consequent increase in benthic food resources (Graf, 1989;Johnson & Wiederholm, 1992;Goedkoop & Johnson, 1996).…”