Aquatic Insects and Benthic Diatoms: A History of Biotic Relationships in Freshwater Ecosystems

Abstract

The most important environmental characteristic in streams is flow. Due to the force of water current, most ecological processes and taxonomic richness in streams mainly occur in the riverbed. Benthic algae (mainly diatoms) and benthic macroinvertebrates (mainly aquatic insects) are among the most important groups in running water biodiversity, but relatively few studies have investigated their complex relationships. Here, we review the multifaceted interactions between these two important groups of lotic organisms. As the consumption of benthic algae, especially diatoms, was one of the earliest and most common trophic habits among aquatic insects, they then had to adapt to the particular habitat occupied by the algae. The environmental needs of diatoms have morphologically and behaviorally shaped their scrapers, leading to impressive evolutionary convergences between even very distant groups. Other less evident interactions are represented by the importance of insects, both in preimaginal and adult stages, in diatom dispersion. In addition, the top-down control of diatoms by their grazers contributes to their spatial organization and functional composition within the periphyton. Indeed, relationships between aquatic insects and diatoms are an important topic of study, scarcely investigated, the onset of which, hundreds of millions of years ago, has profoundly influenced the evolution of stream biological communities.

An Ecological Profile of Hydropsyche alternans (Trichoptera: Hydropsychidae) in Lake Superior, the Last Stronghold of a Once-Dominant Great Lakes Surf Zone Caddisfly

“…Larval hydropsychids are capable of feeding in multiple ways, a fact often overlooked in the trophic ecology literature. Capturing particles with nets is undoubtedly the primary mode of feeding when there is an abundance of high-quality food items present, but grazing algae, especially diatoms from nearby substrates and hunting for small invertebrates, are also common behaviors [ 9 , 10 , 15 , 84 ], particularly during winter in north-temperate waters when net-spinning is abandoned for general grazing [ 10 ]. Meiofaunal organisms that live in lake periphyton assemblages are known to disperse using wave energy to drift to new substrates [ 18 , 85 ].…”

“…Waves and currents deliver suspended food particles to surf zone hydropsychid nets. By limiting the accumulation of fine sediments [ 1 , 2 ], wave energy also promotes the establishment of benthic diatoms, a staple food source of many flowing water insects [ 9 ], including hydropsychids, which capture sloughed cells in their nets and graze directly on epilithic forms [ 10 ]. Large lake net-spinners also presumably enjoy periodic deliveries of planktonic food drawn into the surf zone with upwelling pelagic water following strong offshore winds.…”

Diatom and macroinvertebrate communities dynamic: A co-occurrence pattern analysis on plastic substrates

“…In particular, Coleoptera, Diptera and Trichoptera result the most involved taxa, suggesting the existence of a relationship between insects and diatoms (54; 56; 39). Indeed diatoms, thanks to their high content in fatty acids, are considered high quality food for macroinvertebrates (27). Most of the macroinvertebrates found are scrapers and grazers, supposing to feed on diatom biofilm.…”

“…On the other hand, macroinvertebrates community assemblages are well studied but there is an important lack of knowledge in describing the possible interaction between them and diatom assemblages on plastic supports (19). It's also known that many macroinvertebrate taxa feed on diatoms biofilm through particular structures developed during the evolution (27), but no there is no evidence of segregation or aggregation patterns among them on plastic litter. This paper represents a research project dedicated to the colonization dynamics of macroplastic debris in wetlands by diatoms and macroinvertebrates, with a focus on the "Torre Flavia wetland Special Protection Area"; the present paper is focusing on the distribution models of diatoms and macroinvertebrates on polystyrene and PET substrates, searching for segregation or aggregation patterns describing the observed community structure.…”

Monitoring of Rivers and Streams Conditions Using Biological Indices with Emphasis on Algae: A Comprehensive Descriptive Review toward River Management

“…Algae-based processes lead to the production and synthesis of organic matter (carbon) and allow its entry into the food web via which is available to higher trophic consumers such as fish and waterbirds [127][128][129], and consequently, algae, in terms of freshwater ecosystems [126], are considered to be the most essential part of food webs and biogeochemical cycling, for example, carbon cycling [130]. Epiphytic algae are one of the appropriate food sources for stream invertebrates in an interactive way [131] since freshwater algae carry high concentrations of polyunsaturated fatty acids and in stream food webs, high-quality algae enhances the food value of low-quality riparian leaf litter [129,132,133]. In terms of algal groups, diatoms and cryptophytes supply aquatic invertebrate food of higher quality due to long-chain omega-3 polyunsaturated fatty acids [132,[134][135][136], while omega-3 (n-3) long-chain essential fatty acids (EFA) are higher in running water than brackish [136] and are projected to decrease as world temperature rises [137].…”