Wetland Invertebrate Communities Research Articles

Comparison of taxonomic and size-based approaches to determine the effects of environment and disturbance on invertebrate communities in coastal Chile

• Disturbance from land use change and tsunamis impact Chilean invertebrates. • Aquatic and terrestrial communities respond differently to wetland disturbance. • Coastal wetland invertebrate communities vary with latitudinal gradients. • Disturbance impacts on size vary according to salinity. • Taxonomic diversity and size-based metrics detect different disturbance impacts. The frequency and intensity of extreme events in coastal wetlands is increasing due to climate change. These, in combination with other threats such as habitat loss, can have strong effects on the biodiversity and ecosystem services of coastal wetland ecosystems. Here we examined how traditional (community composition and taxonomic diversity) and alternative indices based on body size (size diversity and the slope of size spectra) respond to single and combined effects of anthropogenic disturbances, extreme event disturbances, and key environmental drivers, for both aquatic and terrestrial invertebrates in Mediterranean coastal wetlands in Chile. We studied 18 coastal wetlands over more than 500 km along the Chilean coast. We applied both univariate (GLMMs and GAMMs) and multivariate statistics (RDA and variation partitioning) to identify additive and non-additive effects on invertebrates. We also examined latitudinal trends, and tested the potential of alternative metrics to detect interactions between disturbances. We found latitude-specific vulnerability to disturbances in Chilean coastal wetlands. Non-additive effects were more important for aquatic invertebrates, while additive effects were more important for terrestrial invertebrates. In many cases, disturbance effects depended on the environmental conditions of study sites, especially salinity. This study suggests that size-based metrics may be better than taxonomic metrics at detecting interactions among different disturbances, especially for aquatic invertebrates.

Effects of Hydrologic Pulsing and Vegetation on Invertebrate Communities in Wetlands

Constructed, mitigation wetlands in the midwestern United States are frequently dominated by a Typha spp. monoculture and their hydrologies are often determined by adjustable control structures. Wetlands provide habitat for multiple macroinvertebrate species, which in turn provide food for other organisms inhabiting the wetlands, such as waterfowl. This study examined the impacts of plant diversity and manipulated hydrology on macroinvertebrate communities. Forty 1-m2 wetland mesocosms were either planted with a monoculture of Typha spp. or with a more diverse plant community of Schoenoplectus tabernaemontani, Juncus effusus, and Sparganium eurycarpum. They were also assigned to one of four hydrologic regimes: steady state, pulsing, deep spring/shallow fall, and shallow spring/deep summer. After one year, macroinvertebrates were sampled in the mesocosms. Mesocosms with deep spring hydrologies were found to have greater taxon diversity than those with other hydrologies, but Chironomidae biomass was the lowest under the deep spring hydrology. Culicidae and Chironomidae were found in higher numbers in mixed vegetation than in Typha spp. Taxon richness and Chironomid biomass were significantly higher in mixed vegetation mesocosms than in Typha spp. monocultures. Results suggest vegetation diversity and hydrological regimes impact macroinvertebrate communities, with potential implications for constructed wetland design and management.

Temporal coherence patterns of prairie pothole wetlands indicate the importance of landscape linkages and wetland heterogeneity in maintaining biodiversity

Wetland ecosystems are diverse, productive habitats that are essential reservoirs of biodiversity. Not only are they home to numerous wetland-specialist species, but they also provide food, water, and shelter that support terrestrial wildlife populations. However, like observed patterns of biodiversity loss, wetland habitats have experienced widespread loss and degradation. In order to conserve and restore wetlands, and thereby the biodiversity they support, it is important to understand how biodiversity in wetland habitats is maintained. Habitat heterogeneity and connectivity are thought to be predominate drivers of wetland biodiversity. We quantified temporal coherence (i.e., spatial synchrony) of wetland invertebrate communities using intra-class correlations among 16 wetlands sampled continuously over 24 years to better understand the relative influences wetland heterogeneity (i.e., internal processes specific to individual wetlands and spatial connectivity and external processes occurring on the landscape) on wetland biodiversity. We found that while wetlands with different ponded-water regimes (temporarily ponded or permanently ponded) often hosted different invertebrate communities, temporal shifts in invertebrate composition were synchronous. We also found the relative importance of internal versus external forces in determining community assembly vary depending on a wetland’s hydrologic function and climate influences. Our results confirm that heterogeneity and spatial connectivity of wetland landscapes are important drivers of wetland biodiversity.

Drought at a coastal wetland affects refuelling and migration strategies of shorebirds

Droughts can affect invertebrate communities in wetlands, which can have bottom-up effects on the condition and survival of top predators. Shorebirds, key predators at coastal wetlands, have experienced widespread population declines and could be negatively affected by droughts. We explored, in detail, the effects of drought on multiple aspects of shorebird stopover and migration ecology by contrasting a year with average wet/dry conditions (2016) with a year with moderate drought (2017) at a major subarctic stopover site on southbound migration. We also examined the effects of drought on shorebird body mass during stopover across 14 years (historical: 1974–1982 and present-day: 2014–2018). For the detailed comparison of two years, in the year with moderate drought we documented lower invertebrate abundance at some sites, higher prey family richness in shorebird faecal samples, lower shorebird refuelling rates, shorter stopover durations for juveniles, and, for most species, a higher probability of making a subsequent stopover in North America after departing the subarctic, compared to the year with average wet/dry conditions. In the 14-year dataset, shorebird body mass tended to be lower in drier years. We show that even short-term, moderate drought conditions can negatively affect shorebird refuelling performance at coastal wetlands, which may carry-over to affect subsequent stopover decisions. Given shorebird population declines and predicted changes in the severity and duration of droughts with climate change, researchers should prioritize a better understanding of how droughts affect shorebird refuelling performance and survival.

Response of Wetland Invertebrate Communities to Local and Landscape Factors in North Central Oklahoma

Invertebrates play an important role influencing wetland functions. Specifically, they provide important food for many waterbirds and other wetland species. To better understand the role environmental factors play in influencing invertebrates, we examined the influence of local and landscape factors on invertebrate communities inhabiting depressional wetlands in Oklahoma. We sampled invertebrates from 58 wetlands during 2009 and 2010. Diversity and taxa richness increased as the season progressed and with vegetation complexity and cover. Diversity and richness decreased as water quality was impacted by nutrient and sediment loading. Local variables occurred more consistently in taxa models than landscape variables. Important local variables included wetland hydrology, vegetation complexity, and water quality, while important landscape variables included density and type of wetlands surrounding wetlands. Land-use practice was the least important landscape variable, but is an important variable due to potential relationships with local variables such as water quality. Low variation (12–26 %) explained by the pCCA suggests other variables may be influencing invertebrate communities, but an alternative explanation is that invertebrates are insensitive to environmental variation. These findings can guide both local management of wetlands and conservation strategies at the watershed or regional scale to benefit not only invertebrates but other wetland dependent species.

Spatial and temporal trends in invertebrate communities of Great Lakes coastal wetlands, with emphasis on Saginaw Bay of Lake Huron

The shallow-sloping coastal bathymetry of Saginaw Bay (Lake Huron) supports broad fringing wetlands. Because benthic invertebrates form an important forage base for fish, wading birds, and waterfowl that utilize these habitats, understanding the drivers of invertebrate community structure has significant management implications. We used Great Lakes basin-wide data from 2002 to place Saginaw Bay wetland invertebrate communities and their environmental drivers into a basin-wide context. Various aspects of community structure were highly correlated with fetch and watershed agriculture across the basin. Saginaw Bay wetlands had relatively high fetch and watershed agriculture and supported unique invertebrate communities, typified by high abundances of many insect taxa. Wetlands from other regions around the basin tended to have more crustaceans and gastropods than the Saginaw Bay wetlands. A 1997–2012 time series from three representative Saginaw Bay wetlands revealed substantial shifts in community structure throughout the period, especially from 2001 through 2004. These years followed a 1-m decline in Lake Huron water levels that occurred between 1997 and 2000. Major community changes included decreasing insect abundance, especially chironomids, and increasing crustacean abundances, especially Hyalella azteca (Amphipoda). While factors in addition to water levels were likely also important, our time series analysis reveals the marked temporal dynamics of Saginaw Bay wetland invertebrate communities and suggests that water level decline may have influenced these communities substantially. Both the spatial and temporal community patterns that we found should be considered in future bio-assessments utilizing wetland invertebrates.

Functional and Phylogenetic Relatedness in Temporary Wetland Invertebrates: Current Macroecological Patterns and Implications for Future Climatic Change Scenarios

In freshwater ecosystems, species compositions are known to be determined hierarchically by large to small‑scale environmental factors, based on the biological traits of the organisms. However, in ephemeral habitats this heuristic framework remains largely untested. Although temporary wetland faunas are constrained by a local filter (i.e., desiccation), we propose its magnitude may still depend on large-scale climate characteristics. If this is true, climate should be related to the degree of functional and taxonomic relatedness of invertebrate communities inhabiting seasonal wetlands. We tested this hypothesis in two ways. First, based on 52 biological traits for invertebrates, we conducted a case study to explore functional trends among temperate seasonal wetlands differing in the harshness (i.e., dryness) of their dry season. After finding evidence of trait filtering, we addressed whether it could be generalized across a broader climatic scale. To this end, a meta-analysis (225 seasonal wetlands spread across broad climatic categories: Arid, Temperate, and Cold) allowed us to identify whether an equivalent climate-dependent pattern of trait richness was consistent between the Nearctic and the Western Palearctic. Functional overlap of invertebrates increased from mild (i.e., Temperate) to harsher climates (i.e., Arid and Cold), and phylogenetic clustering (using taxonomy as a surrogate) was highest in Arid and lowest in Temperate wetlands. We show that, (i) as has been described in streams, higher relatedness than would be expected by chance is generally observed in seasonal wetland invertebrate communities; and (ii) this relatedness is not constant but climate-dependent, with the climate under which a given seasonal wetland is located determining the functional overlap and the phylogenetic clustering of the community. Finally, using a space-for-time substitution approach we suggest our results may anticipate how the invertebrate biodiversity embedded in these vulnerable and often overlooked ecosystems will be affected by long-term climate change.

Bti sprays do not adversely affect non‐target aquatic invertebrates in French Atlantic coastal wetlands

Summary Both the increase in human mobility and climate change contribute to the globalization of vector‐borne diseases. Some mosquito species are efficient disease vectors in Europe, thus increasing the risk of epidemic (re)emergence. Bacillus thuringiensis var. israelensis (Bti) is considered as the most efficient larvicide to control mosquito populations with negligible environmental impacts. However, repeated field applications of Bti over many years raise the question of possible long‐term effects on non‐target invertebrates with putative subsequent alterations of food webs. Environmental effects of Bti have mainly been studied in continental freshwater wetlands. Much less is known for brackish water coastal wetlands. We investigated whether repeated treatments with Bti, applied as VectoBac® WG over seven consecutive years, may affect non‐target invertebrate communities in wetlands of the French Atlantic coast. Particular attention was devoted to invertebrates potentially used as food sources by shorebirds and wading birds. Invertebrates were sampled in the water and sediment of control and VectoBac®‐treated saltmarsh pools between 2006 and 2012. Taxa abundance data were used to calculate community descriptors and to analyse the potential structural changes due to VectoBac® using the principal response curve method and similarity analysis. Physicochemical parameters were measured in the same pools so that homogeneity of the environmental conditions between the control and treated areas could be tested. We demonstrated that long‐term use of VectoBac® WG in French Atlantic coastal wetlands had no influence on the temporal evolution of the taxonomic structure and taxa abundance of non‐target aquatic invertebrate communities, which is highly driven by abiotic factors. In addition, over the long term, the amount of invertebrates that could be used as food resources by birds is maintained in VectoBac®‐treated areas. Synthesis and applications. Reduced application rate and targeted spraying of VectoBac® WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis (Bti). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac®. Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non‐target animal communities potentially exposed to Bti.

Influence of Vegetation on Invertebrate Communities in Grazed Freshwater Wetlands in South-Central Florida

Grazing lands and rangelands are increasingly recognized as an important alternative to other developed land uses for sustaining ecological communities in Florida, the rest of the southeastern United States, and other regions. It is important to understand factors that influence ecological communities on private grazing lands, especially in areas with abundant wetlands, which are often sensitive habitats. This study examined the effects of different vegetation types and simulated grazing (clipping) on the abundance, diversity, and composition of the invertebrate community in seasonally flooded, isolated wetlands on a cattle ranch in south-central Florida. We compared invertebrate communities in wetland areas dominated by two different types of vegetation: emergent macrophytes (Pontederia cordata [Pickerelweed]) and grasses (primarily Luziola fluitans [Southern Watergrass]). There was a trend toward greater abundance and diversity of invertebrates in grass-dominated communities. Experimental removal of vegetation to simulate heavy grazing significantly decreased the abundance and diversity of invertebrates. It also shifted the community composition of invertebrates to favor members of Diptera and Ostracoda. Management practices in grazed wetlands that use light or intermediate levels of grazing, or that foster a greater diversity of vegetative cover, may support more diverse and populous wetland invertebrate communities.

Impacts of cadmium contamination and fish presence on wetland invertebrate communities: An application of population measures and multi-metric tests

Abstract Wetlands are extensively used in heavy metal bioremediation, and it is important to know how biota are impacted by such toxins. I examined invertebrate communities in six experimental wetland ponds in Ithaca, NY, USA to assess the effects of residual cadmium. Three ponds had been treated with cadmium in 1983, and still had average levels of 3.6 mg/kg in the sediment in 2001. Also, two of the cadmium ponds and one non-cadmium pond had predatory fish populations. I quantified the variable effects on invertebrate communities using non-parametric statistics, CCA (canonical correspondence analysis), and three published multi-metric tests ( Burton et al., 1999; Apfelbeck, 2001; Helgen and Gernes, 2001 ). Cadmium effects could not be seen in ponds with fish because invertebrate abundance in these ponds was low. In ponds without fish, cadmium appeared to have significant influence on invertebrate abundance, but not on diversity. None of the multi-metric tests detected a cadmium impact. This study suggests that trophic interactions between fish and invertebrates should be considered in wetland index development and implementation.

Variation in wetland invertebrate communities in lowland acidic fens and swamps

Summary1. Invertebrates were collected semi‐quantitatively from four relatively undisturbed wetlands in the west coast of New Zealand’s South Island: two acidic fens and two swamps. Samples were collected from up to four discrete habitats within each wetland: large open‐water channels, small leads (small, ill‐defined channels with emergent vegetation in them) and large (>10 m diameter) or small (<10 m diameter) ponds. Samples were also collected from different plant species within each wetland, each with different morphology, and from areas without vegetation. This was done to determine whether invertebrate communities varied more between‐wetlands than within‐wetlands, as the results had implications for future wetland monitoring programmes.2. Principal components analysis of water chemistry data revealed striking differences in pH, conductivity and nutrients between the four wetlands. Not surprisingly, pH was lowest in one of the acidic fens, and highest in one of the swamps, where conductivity was also high. Midges (Tanytarsus, Tanypodinae, Orthocladiinae and Ceratopogonidae), nematodes, harpactacoid copepods and the damselfly Xanthocnemis dominated the invertebrate fauna. Orthoclad midges and mites were the most widespread taxa, found in 91 of 94 samples. Diptera were the most diverse invertebrate group, followed by Trichoptera and Crustacea.3. Ordination analysis of the invertebrate data showed that the four wetlands supported different invertebrate communities. However, species composition did not change completely along the ordination axes, suggesting that a relatively species‐poor invertebrate fauna was found in the wetlands. Taxa such as molluscs were restricted to wetlands with high pH. Multi‐response permutation procedures (MRPP) was used to analyse resultant ordination scores to see how they differed according to five terms: ‘Wetland’, ‘Habitat’, ‘Growth Form’, ‘Morphology’ and ‘Plant’. Most of the sample separation along ordination axes reflected differences between wetland, although the ‘Habitat’ and ‘Plant’ terms also explained some of the variation. The ‘Growth Form’ and ‘Morphology’ terms had only minor effects on community composition.4. A multivariate regression tree modelled invertebrate assemblages according to the five predictor terms. The resultant model explained 54.8% of the species variance. The ‘Wetland’ term contributed most to the explanatory power, followed by ‘Habitat’. ‘Growth type’ and ‘Morphology’ explained only a small amount of variance to the regression tree, while the different plant species explained none of the variation.5. Variation in these New Zealand wetland invertebrate communities appears to be controlled most by large‐scale factors operating at the level of individual wetlands, although different habitats within individual wetlands contributed slightly to this variation. Based on these results, sampling programmes to describe wetland invertebrate communities do not need to sample specific habitats or plant types within a wetland. Instead, samples can be collected from a wide range of habitats within individual wetlands, and pooled. Within each habitat, it is unnecessary to collect individual samples from different macrophytes or un‐vegetated areas. Our results suggest that collecting replicate pooled samples from different habitats within each wetland will be sufficient to characterize the invertebrate assemblage of each wetland.

A surface-associated activity trap for capturing water-surface and aquatic invertebrates in wetlands

We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on nondetection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetland. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.

Invertebrate communities of forested limesink wetlands in southwest Georgia, USA: Habitat use and influence of extended inundation

Limesink wetlands are a common aquatic habitat in southwest Georgia, USA. These wetlands are non-alluvial, occupying shallow depressions formed from dissolution of limestone bedrock and collapse of surface sands. They are seasonally inundated, with a typical hydroperiod extending from late February to early July. Little is known about factors influencing invertebrate community structure in limesink wetlands. Recently, it has been suggested that regular inundation and drying are important influences on community structure in some seasonal wetlands. We had an opportunity to examine this hypothesis in 3 forested limesink wetlands. Quantitative samples of invertebrates were taken monthly on benthic and wood surfaces from March 1994 through July 1995. This included a period of unusually heavy precipitation, summer and autumn of 1994, when the wetlands would normally be dry. Immediately following inundation, benthic samples were dominated by amphipods (Crangonyx sp.), isopods (Caecidotea sp.), cladocerans, and copepods. Maximum total densities (1000–4000 individuals per m2) were observed within 3 months of inundation. During summer and autumn, densities decreased (< 500 individuals per m2), and the benthos was dominated by larval chironomids. Wood surfaces were dominated by chironomids, with greatest densities (1000–3000 individuals per m2) observed in summer and autumn. Although not quantified, freshwater sponge became very abundant on wood surfaces during autumn. During the following spring (1995), invertebrate densities on sediments remained low, and few amphipods, isopods, cladocerans, or copepods were collected. Chironomids remained very abundant on wood. Our results suggest that extended inundation is a disturbance to some elements of wetland invertebrate communities. Extended inundation may cause short-term reductions in populations by eliminating summer refugia (amphipoda, isopoda) or by altering environmental cues necessary for the completion of life cycles (cladocerans, copepods).

Multivariate pattern analysis of wetland invertebrate communities and environmental variables in Western Australia

Abstract Macro‐invertebrates, zooplankton and water quality variables were sampled at 33 wetlands near Perth, Western Australia, in January‐February 1989. Wetlands were classified and ordinated using the invertebrate data. Correlations of environmental variables with the ordination were calculated and the importance of seasonality and geomorphology of the wetlands were investigated. The wetlands were also classified and ordinated using the chemical data. Analysis of variance was used to compare species richness, abundances of all invertebrates, macro‐invertebrates, copepods and total phosphorus levels among groups. Six groups of wetlands were identified from the invertebrate data, two of which were outliers on the basis of very low pH and high salinity, respectively. The majority of the wetlands grouped on the basis of their degree of nutrient enrichment and colour. The analyses of chemical data gave similar groups. The coloured wetlands and least nutrient enriched non‐coloured wetlands were identified as being closest to the probable state of wetlands prior to European settlement. The greatest numbers of rare species were found in wetlands from these two groups. Species richness was significantly higher in the moderately enriched wetlands than in any other group but decreased in the most enriched wetlands where abundances of invertebrates were highest. Changes in community composition among the groups of wetlands are discussed. The most highly nutrient enriched wetlands were dominated by cosmopolitan species with high abundances, whereas less enriched and coloured wetlands had species with more restricted distributions and lower abundances.

The Ecology of Invertebrates in Great Lakes Coastal Wetlands: Current Knowledge and Research Needs

This review summarizes the comparatively sparse information on the community structure, population dynamics, secondary productivity, and trophic relationships of invertebrates in coastal wetlands of the Laurentian Great Lakes. Community structure is discussed in terms of separate but interrelated communities comprising the zooplankton, zoobenthos, epiphytic invertebrates, and neuston. The composition and dynamics of these communities are controlled by a complex set of interacting and continuously changing biotic and abiotic factors. Much additional research is required before a fundamental understanding of invertebrate ecology in Great Lakes coastal wetlands can be achieved. Particular research needs include elucidation of geographic differences in community structure and dynamics within and among wetlands of the same and contrasting types; the influence of micro- and macro-habitat differences and environmental stresses on invertebrate communities; the contribution of invertebrates to energy and materials flow in wetland food webs; the interactions of wetland invertebrates with the adjoining lake biota; the role of invertebrates in nutrient and pollutant transformations and cycling within the wetlands; the impact of changing land uses in wetland watersheds and of wetland alteration on the invertebrate communities, and the consequential impacts of these changes on the ecology of the lakes; and the impact on wetland invertebrate communities of predation pressure and competition from exotic species.