Leonardo Maltchik

Climate change is rapidly driving global biodiversity declines. How wetland macroinvertebrate assemblages are responding is unclear, a concern given their vital function in these ecosystems. Using a data set from 769 minimally impacted depressional wetlands across the globe (467 temporary and 302 permanent), we evaluated how temperature and precipitation (average, range, variability) affects the richness and beta diversity of 144 macroinvertebrate families. To test the effects of climatic predictors on macroinvertebrate diversity, we fitted generalized additive mixed-effects models (GAMM) for family richness, and generalized dissimilarity models (GDMs) for total beta diversity. We found non-linear relationships between family richness, beta diversity and climate. Maximum temperature was the main climatic driver of wetland macroinvertebrate richness and beta diversity, but precipitation seasonality was also important. Assemblage responses to climatic variables also depended on wetland water permanency. Permanent wetlands from warmer regions had higher family richness than temporary wetlands. Interestingly, wetlands in cooler and dry-warm regions had the lowest taxonomic richness, but both kinds of wetlands supported unique assemblages. Our study suggests that climate change will have multiple effects on wetlands and their macroinvertebrate diversity, mostly via increases in maximum temperature, but also through changes in patterns of precipitation. The most vulnerable wetlands to climate change are likely those located in warm-dry regions, where entire macroinvertebrate assemblages would be extirpated. Montane and high-latitude wetlands (i.e., cooler regions) are also vulnerable to climate change, but we do not expect entire extirpations at the family level.

Analyses of biota at lower latitudes may presage impacts of climate change on biota at higher latitudes. Macroinvertebrate assemblages in depressional wetlands may be especially sensitive to climate change because weather‐related precipitation and evapotranspiration are dominant ecological controls on habitats, and organisms of depressional wetlands are temperature‐sensitive ectotherms. We aimed to better understand how wetland macroinvertebrate assemblages were structured according to geography and climate. To do so, we contrasted aquatic‐macroinvertebrate assemblage structure (family level) between subtropical and temperate depressional wetlands of North and South America using presence–absence data from 264 of these habitats across the continents and more‐detailed relative‐abundance data from 56 depressional wetlands from four case‐study locations (North Dakota and Georgia in North America; southern Brazil and Argentinian Patagonia in South America). Both data sets roughly partitioned wetland numbers equally between the two climatic zones and between the continents. We used ordination methods (PCA and NMDS) and tests of multivariate dispersion (PERMDISP) to assess the distribution and the homogeneity in variation in the composition of macroinvertebrate assemblages across climates and continents, respectively. We found that macroinvertebrate assemblage structures in the subtropical depressional wetlands of North and South America were similar to each other (at the family level), while assemblages in the North and South American temperate wetlands were unique from the subtropics, and from each other. Tests of homogeneity of multivariate dispersion indicated that family‐level assemblage structures were more homogeneous in wetlands from the subtropical than the temperate zones. Our study suggests that ongoing climate change may result in the homogenization of macroinvertebrate assemblage structures in temperate zones of North and South America, with those assemblages becoming enveloped by assemblages from the subtropics. Biotic homogenization, more typically associated with other kinds of anthropogenic factors, may also be affected by climate change.

Wetlands provide vital habitat for biodiversity and relevant ecosystem services to human population. The rapid transformation of freshwater wetlands to grow food crops became the wetlands strongly threatened by human activities. Restoration efforts related to wetlands have been widely attempted; however, science‐based guidelines are relatively scarce. Here, we analyzed whether different levels of topsoil addition from natural wetlands in the sediment from rice fields influence the zooplankton communities. Our hypothesis was that the richness and abundance of hatchlings would be higher in treatments with high topsoil addition from natural wetlands, followed by treatments with low addition. In the laboratory, eight field sediment samples were incubated for zooplankton hatching in four treatments: rice fields, rice fields added with low (5%) and medium (30%) quantities of sediment from natural wetlands, and natural wetlands. A total of 4,493 hatchlings belonging to 24 taxa were observed in the experiment. While zooplankton richness and abundance did not differ between sediment treatments, significant differences in species composition associated with topsoil addition were observed. SIMPER analysis showed that topsoil addition from natural wetlands enhanced the abundance of cladocerans and larval copepods. Our results showed that sediments from natural wetlands have a bank of zooplankton dormant eggs that can help the recovery of wetlands disturbed by rice fields. The addition of natural wetland sediments in areas disturbed by rice fields modifies the zooplankton composition of the rice fields, aiding the recovery of disturbed natural wetlands for rice production.

The main goal of this study was to test the effect of the presence of nesting waterbirds on the taxonomic structure (richness, abundance and composition) of macroinvertebrate communities in southern Brazilian wetlands. Macroinvertebrate communities were seasonally sampled in eight intermittent wetlands differing according to the occurrence of nesting colonies of waterbirds (four with the presence of rookeries; four without). The influence of nutrients and water and sediment physicochemical variables on macroinvertebrate communities was also assessed. The community structure of aquatic macroinvertebrates was not affected by the presence of colonies of nesting waterbirds. Rather, macroinvertebrate communities varied seasonally and they were influenced by water-level environmental variables. Richness and composition changed among seasons and were influenced by nutrients and water physicochemical variables. Water turbidity and total dissolved solids influenced macroinvertebrate richness...

Assessment of β diversity patterns in relation to environmental and spatial drivers can provide useful insights into the underlying mechanisms structuring communities (deterministic and dispersal limitation). However, the relative importance of each mechanism and driver of β diversity patterns in freshwater communities is assumed to change with ecosystem type, scale of observation, and among groups with different dispersal abilities. We assessed β diversity patterns of assemblages of odonate larvae in relation to geographical distances and scale-specific environmental drivers in southern Brazilian coastal ponds along a latitudinal gradient. We expected to find similar contributions of deterministic and dispersal limitation mechanisms to odonate assemblages and distinct patterns of β diversity between suborders Anisoptera and Zygoptera. We found low values of β diversity (probably related to distribution of generalist taxa and environmental conditions constituted by temporary ponds). Mantel and partial Mantel tests detected distinct relationships between dissimilarity in scale-specific drivers and geographical distances with β diversity of Odonata. Zygoptera was influenced by dissimilarity in local- (presence of riparian vegetation and connectivity) and regional-level (climate) variables, whereas Anisoptera was influenced by geographical distances. Our results supported our hypothesis that changes in the composition of assemblages of odonate larvae in temporary ponds were jointly driven by deterministic and dispersal limitation mechanisms. Furthermore, the similar contributions of nestedness and replacement components and the differing responses of Anisoptera and Zygoptera to local- and regional-level environmental drivers and geographical distances indicate that the relative importance of environmental and spatial drivers to β diversity patterns in ponds is scale-specific.

... and rivers, lentic ecosystems are believed to be isolated, largely decoupled from the surroundinglandscape (Dodds 2002). ... macroinvertebrates at fine spatial scales ... This pattern may have resulted from similar abiotic characteristics or biotic interactions (eg, competition, predation ...

ABSTRACT This study assessed the influence of an artificial sandbar opening on the macroinvertebrate richness, abundance and composition of the Lagoa do Peixe floodplains in the only Ramsar site in southern Brazil. The Lagoa do Peixe has its connection with the sea artificially opened every year at the end of winter. However, this management intervention has been carried out without the evaluation of the impact of this opening in the aquatic biodiversity. Six samplings were carried out over two years (from March 2008 to October 2009) which encompassed two artificial sandbar openings. The mean richness and abundance were lower in the floodplain sites influenced by the artificial sandbar opening (opened wetlands) than in the floodplain sites not influenced by this event (natural wetlands). Water salinity was higher in opened wetlands than in natural wetlands during the open sandbar samplings. The richness was negatively associated with water salinity, and the abundance was positively associated with hydroperiod, and negatively associated with conductivity. The composition of macroinvertebrate taxa was different between opened and natural wetlands. Our results suggest that artificial sandbar openings have a negative impact on freshwater macroinvertebrate communities in southern Brazil floodplain wetlands. Hydrologic variation and increase of salinity related to this management may be the main factors of the change in the richness, abundance and composition in opened wetlands. We concluded that the artificial sandbar opening should be carefully re-analysed or forbidden, since this management practice may be jeopardizing the aquatic macroinvertebrate community in a National Park and Ramsar site, where the biodiversity conservation is a priority and protected by Brazilian laws.

ABSTRACT Odonate larvae play an important role in wetland systems, providing food for many fish species and birds. Besides, they are important predators in these ecosystems.However, studies of factors that determine odonate species richness and distribution in wetlands are scarce in the Neotropical region. The objectives of this study were to: 1) conduct a survey of the diversity of odonate larvae in southern Brazil wetlands, and 2) determine how much variation in odonate richness, abundance and composition is explained by wetland area, altitude, water conductivity and nitrate, hydroperiod, and dominant aquatic vegetation in 140 wetlands in an extensive area of the Neotropical region (—280,000 km², southern Brazil). A total of 4,039 individuals distributed among five families and 28 genera were collected.Libellulidae, Coenagrionidae and Aeshnidae were the families that showed the greatest richness. Erythrodiplax was observed in more than 70% of the sampled wetlands, and comprised 61% of individuals collected. Richness was negatively associated with wetland area and nitrate concentration. Odonate abundance was negatively associated with water conductivity and nitrate, and it was higher in aquatic beds than in emergent wetlands.Richness and abundance were higher in permanent than in intermittent wetlands. Variation in odonate composition was correlated with wetland altitude, area and water conductivity.Hydroperiod and dominant aquatic vegetation also influenced composition. Our results showed that southern Brazil wetlands are important habitats for 28 odonate genera, and that richness, abundance and composition are influenced mainly by hydroperiod, nitrate, and aquatic vegetation type. These results should be seen as important to determine the environmental factors that shape and maintain odonate diversity in southern Brazil wetlands. As larvas de Odonata desempenham um importante papel ecológico nas áreas úmidas, constituindo alimento para muitas espécies de peixes e aves. Além disso, esses organismos são importantes predadores nesses ecossistemas. Entretanto, os fatores ambientais que determinam a riqueza e a distribuição de Odonata em áreas úmidas da região Neotropical são pouco conhecidos. Os objetivos desse estudo foram: 1) realizar um inventário da diversidade de larvas de Odonata em áreas úmidas no Sul do Brasil, e 2) verificar se a riqueza, abundância e composição de Odonata são explicadas pelo tamanho da área ùmida, altitude, condutividade e nitrato da água, hidroperíodo, e vegetação aquática dominante em 140 áreas úmidas em uma extensa área da região Neotropical (~280.000 km², Sul do Brasil). Um total de 4.039 indivíduos distribuídos em cinco famílias e 28 géneros foi amostrado nas áreas úmidas. Libellulidae, Coenagrionidae e Aeshnidae foram as famílias que apresentaram a maior riqueza. O gênero Erythrodiplax foi encontrado em mais de 70% das áreas úmidas, e correspondeu a 61% do total de indivíduos coletados. A riqueza esteve negativamente associada com o tamanho da área ùmida e com o nitrato da água. A abundância esteve negativamente associada com a condutividade e nitrato da água, sendo maior nas áreas úmidas herbáceas do que nas emergentes. A riqueza e a abundância foram maiores nas áreas úmidas permanentes do que nas intermitentes. A composição teve relação com a altitude, tamanho da área ùmida e condutividade da água. O hidroperíodo e a vegetação aquática também influenciaram a composição de larvas de Odonata. As áreas úmidas no Sul do Brasil são habitats importantes para 28 géneros de Odonata, sendo que a riqueza, a abundância e a composição foram influenciadas principalmente pelo hidroperíodo, nitrato da água e vegetação aquática. Esses resultados contribuem para o conhecimento dos fatores ambientais que influenciam a diversidade de Odonata em áreas úmidas no Sul do Brasil.

... Leonardo Maltchik 1, *, Cristina Stenert 1 , Marcia Regina Spies 2 , and Ana Emilia Siegloch 2. ... type of microhabitat as the main environmental variables that relate to distribution patterns of Ephemeroptera and Trichoptera (eg, Bispo et al., 2001, 2006; Costa and Melo ...

The expansion of rice fields is one of the main human activities responsible for the decline of natural wetlands throughout the world. However, rice fields have been recognized as having considerable potential value for many aquatic species. In this sense, an important question from the point of view of biodiversity conservation is the adequacy of these agricultural wetlands as an

In the Neotropics where fragmentation is common, environmental factors structuring fish communities are poorly known. In this study two hypotheses were tested in 13 coastal wetlands of southern Brazil: 1) physical features (such as wetland area, habitat diversity, water depth and temperature, and water and sediment chemistry) are important determinants of richness, density and composition of fish assemblages; and 2)

Small wetlands are particularly important habitats for amphibians due to their close dependence on these habitats for their critical life-story functions. The constant degradation of wetland systems has been considered as one of the main causes for the declining of the anuran population observed around the world, including in southern Brazil. The objective of this study was to analyze the richness, abundance, and composition of the amphibian assemblage in a small pond associated to a floodplain system in a Neotropical region in Southern Brazil over a year. A total of 19 amphibian samplings were carried out over a year (from September 2004 to August 2005), and the survey was made in five transects (30 x 2 m) distributed at random along the studied pond. A total of 17 anuran species distributed in six families (Bufonidae, Cycloramphidae, Hylidae, Leiuperidae, Leptodactylidae, and Microhylidae) were observed. The Hylidae family represented 35.3% of the total species, and 22.0% of the total individuals observed over the studied period. Rhinella fernandezae was the most abundant species, representing 24.7% of the all collected individuals. The amphibian richness and abundance did not show any variation during the study period and between phases with and without superface water. However, the anuran composition changed between periods with surface water and without surface water. Air temperature and rainfall did not influence the amphibian richness and abundance. The high diversity and abundance of the anuran observed (17 species and 332 individuals) point to the need to include small wetlands in the biodiversity conservation programs in Southern Brazil, mainly when 90% have already disappeared due to anthropic activities. But these results should serve as hypotheses for long-term investigations in a larger area.

Segregated species co-occurrence and nestedness are two ecological patterns used to measure assemblage structure. We investigated species co-occurrence and nestedness patterns in assemblages of tadpoles and adult anurans in 30 coastal ponds in southern Brazil. Ponds varied in hydroperiod and were classified as temporary or permanent. We explored whether co-occurrence or nestedness varied among ponds in each hydroperiod. Species co-occurrence patterns were analyzed using the C-score index and three null models. In order to quantify nestedness, we used the nestedness metric based on overlap and decreasing fill (NODF). We found seventeen anuran species; however, only 13 species were observed in breeding activity, and 11 species were observed as tadpoles. The co-occurrence and nestedness analyses showed that anuran assemblages exhibit non-random patterns that were generally contingent on the hydroperiod and pond area. Only species in non-breeding adult anurans assemblages showed signifi...

The destruction of wetlands due to afforestation areas is a common activity in temperate and subtropical regions in Southern America. The expansion of pine in the Coastal Plain of Southern Brazil is out of control and its impacts on aquatic biodiversity are little known. We tested the following hypotheses: the pine occurrence diminishes the anuran richness and abundance in ponds and it changes the anuran composition; the beta-diversity between pine and native grassland matrix ponds (natural ponds) is determined mainly by nestedness. Sampling was carried out from 2007 to 2009 in five ponds in pine invasion matrix and five ponds in native grassland matrix. The natural ponds showed a greater richness of tadpoles (10 species) than pine ponds (5 species). The mean richness of adults was higher in natural ponds than pine ponds throughout the entire study. The species composition was different between natural and pine ponds, for both adults and tadpoles. Comparing natural ponds with each o...

The rapid degradation of wetlands worldwide accentuates the urgent need for ecological data to help manage and protect the threatened biodiversity in the remaining often-fragmented wetlands. In the Neotropics where fragmentation is common, environmental factors structuring aquatic macroinvertebrate communities are poorly known. We tested the hypothesis that physical features, such as wetland area, habitat diversity, water depth and temperature, and water and sediment chemistry are important correlates with richness, density and composition of wetland macroinvertebrate assemblages in Brazil. If so, do these correlations differ between summer and winter? A total of 16 895 individuals across 61 families were collected. Richness was positively associated with habitat diversity and water depth and negatively associated with water temperature. Macroinvertebrate density was negatively associated with water depth, and positively correlated with habitat diversity, percentage of sediment orga...