Spatial and seasonal variability of emergent aquatic insects and nearshore spiders in a subtropical estuary

2019 ◽  
Vol 70 (4) ◽  
pp. 541 ◽  
Author(s):  
Martha J. Zapata ◽  
S. Mažeika P. Sullivan

Variability in the density and distribution of adult aquatic insects is an important factor mediating aquatic-to-terrestrial nutritional subsidies in freshwater ecosystems, yet less is understood about insect-facilitated subsidy dynamics in estuaries. We surveyed emergent (i.e. adult) aquatic insects and nearshore orb-weaving spiders of the families Tetragnathidae and Araneidae in a subtropical estuary of Florida (USA). Emergent insect community composition varied seasonally and spatially; densities were lower at high- than low-salinity sites. At high-salinity sites, emergent insects exhibited lower dispersal ability and a higher prevalence of univoltinism than low- and mid-salinity assemblages. Orb-weaving spider density most strongly tracked emergent insect density rates at low- and mid-salinity sites. Tetragnatha body condition was 96% higher at high-salinity sites than at low-salinity sites. Our findings contribute to our understanding of aquatic insect communities in estuarine ecosystems and indicate that aquatic insects may provide important nutritional subsidies to riparian consumers despite their depressed abundance and diversity compared with freshwater ecosystems.

2019 ◽  
Vol 70 (4) ◽  
pp. 609
Author(s):  
Martha J. Zapata ◽  
S. Mažeika P. Sullivan

Variability in the density and distribution of adult aquatic insects is an important factor mediating aquatic-to-terrestrial nutritional subsidies in freshwater ecosystems, yet less is understood about insect-facilitated subsidy dynamics in estuaries. We surveyed emergent (i.e. adult) aquatic insects and nearshore orb-weaving spiders of the families Tetragnathidae and Araneidae in a subtropical estuary of Florida (USA). Emergent insect community composition varied seasonally and spatially; densities were lower at high- than low-salinity sites. At high-salinity sites, emergent insects exhibited lower dispersal ability and a higher prevalence of univoltinism than low- and mid-salinity assemblages. Orb-weaving spider density most strongly tracked emergent insect density rates at low- and mid-salinity sites. Tetragnatha body condition was 96% higher at high-salinity sites than at low-salinity sites. Our findings contribute to our understanding of aquatic insect communities in estuarine ecosystems and indicate that aquatic insects may provide important nutritional subsidies to riparian consumers despite their depressed abundance and diversity compared with freshwater ecosystems.


2020 ◽  
Author(s):  
Scott Hotaling ◽  
Joanna L. Kelley ◽  
Paul B. Frandsen

AbstractAquatic insects comprise 10% of all insect diversity, can be found on every continent except Antarctica, and are key components of freshwater ecosystems. Yet aquatic insect genome biology lags dramatically behind that of terrestrial insects. If genomic effort was spread evenly, one aquatic insect genome would be sequenced for every ∼9 terrestrial insect genomes. Instead, ∼24 terrestrial insect genomes have been sequenced for every aquatic insect genome. This discrepancy is even more dramatic if the quality of genomic resources is considered; for instance, while no aquatic insect genome has been assembled to the chromosome level, 29 terrestrial insect genomes spanning four orders have. We argue that a lack of aquatic insect genomes is not due to any underlying difficulty (e.g., small body sizes or unusually large genomes) yet it is severely hampering aquatic insect research at both fundamental and applied scales. By expanding the availability of aquatic insect genomes, we will gain key insight into insect diversification and empower future research for a globally important taxonomic group.Simple SummaryAquatic insects comprise 10% of all insect diversity, can be found on every continent except Antarctica, and are key components of freshwater ecosystems. Yet aquatic insect genome biology lags dramatically behind that of terrestrial insects. If genomic effort was spread evenly, one aquatic insect genome would be sequenced for every ∼9 terrestrial insect genomes. Instead, ∼24 terrestrial insect genomes have been sequenced for every aquatic insect genome. We argue that the limited availability of aquatic insect genomes is not due to practical limitations—e.g., small body sizes or overly complex genomes—but instead reflects a lack of research interest. We call for targeted efforts to expand the availability of aquatic insect genomic resources to gain key molecular insight into insect diversification and empower future research.


Author(s):  
T. Kubendran ◽  
M. Ramesh

<div><p><em>The Western Ghats, running parallel to the west coast of India between 8° N and 21° N is a prominent feature of the peninsular India. In freshwater biodiversity hotspots like the Western Ghats, no information is available on activates and ecological role of adult aquatic insect in the riparian zone of streams.</em><strong><em> </em></strong><em>Most adult aquatic insects that emerge from streams live briefly in the nearby riparian zone. Adult activities, such as mating dispersal and feeding influence their distribution in the terrestrial habitat. An observation at Kurangani streams, Western Ghats, India has shown that both numbers and biomass of adult aquatic insects are greatest in the near stream vegetation; however, adult insects can be relatively common 1 to 10 feet from the stream. Why because, adult aquatic insects are abundant and they are primary food resource for many riparian insectivores. The role of adult aquatic insects in the riparian zone must be better understood for riparian and aquatic food chain to be complete. </em></p></div>


Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 601 ◽  
Author(s):  
Scott Hotaling ◽  
Joanna L. Kelley ◽  
Paul B. Frandsen

Aquatic insects comprise 10% of all insect diversity, can be found on every continent except Antarctica, and are key components of freshwater ecosystems. However, aquatic insect genome biology lags dramatically behind that of terrestrial insects. If genomic effort was spread evenly, one aquatic insect genome would be sequenced for every ~9 terrestrial insect genomes. Instead, ~24 terrestrial insect genomes have been sequenced for every aquatic insect genome. This discrepancy is even more dramatic if the quality of genomic resources is considered; for instance, while no aquatic insect genome has been assembled to the chromosome level, 29 terrestrial insect genomes spanning four orders have. We argue that a lack of aquatic insect genomes is not due to any underlying difficulty (e.g., small body sizes or unusually large genomes), yet it is severely hampering aquatic insect research at both fundamental and applied scales. By expanding the availability of aquatic insect genomes, we will gain key insight into insect diversification and empower future research for a globally important taxonomic group.


2016 ◽  
Vol 67 (11) ◽  
pp. 1644 ◽  
Author(s):  
Marina S. Dalzochio ◽  
Renata Baldin ◽  
Cristina Stenert ◽  
Leonardo Maltchik

Changes to biodiversity have mainly been assessed using taxonomic diversity indices. Although these approaches contribute to our scientific understanding of species richness and composition patterns, trait-based metrics may be more useful for detecting responses to land-use change. We compared functional diversity of aquatic insect communities along a gradient of agricultural intensification. Our goal was to compare functional redundancy, functional richness, functional evenness and functional divergence among natural ponds, and organic and conventional rice fields. We recorded 15606 aquatic insects distributed across 61 genera. The highest functional redundancy and richness were observed in the natural ponds, followed by organic rice fields and conventional ones. The functional composition varied among natural ponds and rice fields, and differed between organic and conventional rice fields. Organic management favoured the establishment of some pond insect traits, such as predatory taxa, in rice agroecosystems. Our analysis suggests that the conversion of ponds to rice fields results in a shift to less specialised aquatic insect communities with altered functional composition groups. Nevertheless, this result should not be seen as a negative reflection on organic rice fields, because organic rice production affords a better compromise between agricultural production and ecosystem function than conventional agriculture.


2010 ◽  
Vol 67 (3) ◽  
pp. 570-579 ◽  
Author(s):  
Rachel L. Malison ◽  
Colden V. Baxter

We investigated the midterm effects of wildfire (in this case, five years after the fire) of varying severity on periphyton, benthic invertebrates, emerging adult aquatic insects, spiders, and bats by comparing unburned sites with those exposed to low severity (riparian vegetation burned but canopy intact) and high severity (canopy completely removed) wildfire. We observed no difference in periphyton chlorophyll a or ash-free dry mass among different burn categories but did observe significantly greater biomass of benthic invertebrates in both high severity burned and unburned reaches versus low severity burned reaches. Moreover, a significantly greater flux of adult aquatic insect emergence occurred at sites that experienced high severity fire versus low severity burned and unburned sites. The greatest number of spiders and bat echolocation calls were also observed at sites of high severity fire. Our results suggest that fires of different severity may have very different affects on stream-riparian food webs and that high severity wildfire may lead to an extended “fire pulse” that stimulates aquatic productivity and flux of prey to terrestrial habitats, driving local increases in riparian consumers.


2021 ◽  
Vol 16 (2) ◽  
pp. 514-529
Author(s):  
Hebbal Rajendra Abhilash ◽  
Malliah Mahadevaswamy

Water is an indispensable natural resource vital for the survival of all life forms. It contributes significantly to the country's economic prosperity and general well-being. As a result, understanding the status of water bodies is crucial to assure their long-term use. A study on water quality parameters and aquatic insect community was therefore carried on the surface waters of Dalvoy Lake which is spread over an area of 133.43 acres and having a length of 2.2 km. Monthly water samples were collected using one-litre labeled plastic containers from three locations between the hours of 8 a.m. and 10 a.m. Water quality analysis was conducted following standard methods and compared to drinking water specifications. The dissolved oxygen content, total hardness, conductivity, total dissolved solids, and turbidity exceeded the permissible limits. Aquatic insects were collected from the same locations and preserved in 4% formalin. A total of 15 species of aquatic insects belonging to four orders, Hemiptera, Coleoptera, Diptera, and Ephemeroptera, were identified in this study. The Hemiptera was shown to be the largest group comprising of 8 species; 4 species of Diptera; 2 species of Coleoptera and a lone species of Ephemeroptera. The computation of aquatic insect dominance status using Engelmann's Scale revealed Diplonychus rusticus, Anisops sp., Enithares sp., Chironomous sp. and Culex sp. as dominant. Biodiversity metrics like the Shannon Index (1.4-2.11) and the evenness index (0.50-0.66) reflect the agitation of the system. Based on the results of the water quality index (163.67) and aquatic insect assemblage, it is evident that the water in Dalvoy Lake is deteriorated and is unfit for domestic usage. The study also indicated the abundance of two genera Chironomous and Culex of the Diptera order which are the index of water pollution. Thus, the present study calls for urgent and strict vigilance and continuous monitoring of this perennial water body for conservation and sustainable management.


2017 ◽  
Vol 43 (2) ◽  
pp. 286 ◽  
Author(s):  
Leandro S. Brasil ◽  
Nubia França Da Silva Giehl ◽  
Joana Darc Batista ◽  
Bethânia Oliveira de Resende ◽  
Helena Soares Ramos Cabette

A major part of the mechanisms that affects species distribution is related to environmental conditions. Within a stream channel the accumulation of substrates like litter, roots, stones, gravel and sand create habitats that act as shelter and/or food source to aquatic communities, in this way supporting, or not, the establishment of different species. Based on this fact we verified the structure of aquatic insect communities in organic and inorganic habitats within Cerrado streams. Tested for differences on genera richness (i), individual abundance (ii) and genera composition (iii), and also (iv) verified if there are any indicator genera, which are faithful and specific to organic or inorganic habitats. Sampled organic (litter) and inorganic (sand and gravel) substrates in five sections of three streams and collected individuals of the orders Ephemeroptera, Plecoptera, Trichoptera, Odonata and Heteroptera (EPTOH). Community composition differed between habitats, with organic ones having higher richness and abundance, besides being the only habitat that presented faithful and specific genera (six). It is argued that this difference may be caused due to shelter and food supply provided by organic substrates.


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9176
Author(s):  
Noriko Uchida ◽  
Kengo Kubota ◽  
Shunsuke Aita ◽  
So Kazama

Environmental DNA (eDNA) analysis provides an efficient and objective approach for monitoring and assessing ecological status; however, studies on the eDNA of aquatic insects, such as Ephemeroptera, Plecoptera, and Trichoptera (EPT), are limited despite its potential as a useful indicator of river health. Here, we investigated the community structures of aquatic insects using eDNA and evaluated the applicability of eDNA data for calculating assessment indices. Field surveys were conducted to sample river water for eDNA at six locations from upstream to downstream of two rivers in Japan in July and November 2016. Simultaneously, aquatic insects were collected using the traditional Surber net survey method. The communities of aquatic insects were revealed using eDNA by targeting the cytochrome oxidase subunit I gene in mitochondrial DNA via metabarcoding analyses. As a result, the eDNA revealed 63 families and 75 genera of aquatic insects, which was double than that detected by the Surber net survey (especially for families in Diptera and Hemiptera). The seasonal differences of communities were distinguished by both the eDNA and Surber net survey data. Furthermore, the total nitrogen concentration, a surrogate of organic pollution, showed positive correlations with biotic environmental assessment indices (i.e., EPT index and Chironomidae index) calculated using eDNA at the genus-level resolution but the indices calculated using the Surber net survey data. Our results demonstrated that eDNA analysis with higher taxonomic resolution can provide as a more sensitive environmental assessment index than the traditional method that requires biotic samples.


Hydrobiologia ◽  
2021 ◽  
Author(s):  
P. Saffarinia ◽  
K. E. Anderson ◽  
D. B. Herbst

AbstractFreshwater systems are projected to experience increased hydrologic extremes under climate change. To determine how small streams may be impacted by shifts in flow regimes, we experimentally simulated flow loss over the span of three summers in nine 50 m naturally fed stream channels. The aquatic insect community of these streams was sampled before, during, and after experimental drought treatments as well as following one unforeseen flood event. Abundance, richness, and beta diversity were measured as indicators of biotic effects of altered flow regimes. Abundance declined in proportion to flow loss. In contrast, we observed a threshold response in richness where richness did not decrease except in channels where losses of surface flow occurred and disconnected pools remained. The flood reset this pattern, but communities continued their prior trajectories shortly thereafter. Beta diversity partitions suggested no strong compositional shifts, and that the effect of drought was largely experienced uniformly across taxa until flow cessation. Pools served as a refuge, maintaining stable abundance gradients and higher richness longer than riffles. Upon flow resumption, abundance and richness returned to pre-treatment levels within one year. Our results suggest that many taxa present were resistant to drought conditions until loss in surface flow occurred.


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