Spatial and environmental drivers of macrophyte diversity and community composition in temperate and tropical calcareous rivers

Abstract

Murphy, Kevin J.. 2016. Spatial and environmental drivers of macrophyte diversity and community composition in temperate and tropical calcareous rivers. Aquatic Botany, 132.The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Spatial and environmental drivers of macrophyte diversity and community 1 composition in temperate and tropical calcareous rivers 2 3Abstract 30The hypothesis was examined that sources of variation in macrophyte species 31 richness (alpha-diversity: S) and community composition ("species-set"), attributable to 32 spatial and environmental, variables, may differ in importance between tropical and 33 temperate calcareous rivers (>10 mg CaCO 3 L -1 ). To test this hypothesis geographic, 34 environmental, and aquatic vegetation data were acquired for 1151 sites on calcareous 35 rivers within the British Isles, supporting 106 macrophyte species (mean S: 3.1 species 36 per sample), and 203 sites from Zambian calcareous rivers, supporting 255 macrophyte 37 species (mean S: 8.3 species per sample). The data were analysed using an 38 eigenfunction spatial analysis procedure, Moran's Eigenvector Maps (MEM), to assess 39 spatial variation of species richness and community composition at large regional scale 40 (>10 5 km 2 : British Isles and Zambia); and at medium catchment scale (10 4 -10 5 km 2 : 41 British Isles only). Variation-partitioning was undertaken using multiple regression for 42 species richness data, and partial redundancy analysis (pRDA) for community data. For 43 the British Isles, spatial and environmental variables both significantly contributed to 44 explaining variation in both species richness and community composition. In addition, a 45 substantial amount of the variation in community composition, for the British Isles as a 46 whole and for some RBUs, was accounted for by spatially-structured environmental 47 variables. In Zambia, species richness was explained only by pure spatial variables, but 48 environmental and spatially-structured environmental variables also explained a 49 significant part of the variation for community composition. At medium-scale, in the 50 British Isles, species richness was explained by spatial variables, and only for four of 51 the six RBUs. 52 53

Environmental drivers of freshwater macrophyte diversity and community composition in calcareous warm‐water rivers of America and Africa

“…Our results support previous studies which suggest that, in freshwater systems, local driving factors (chemical, physical or biological) seem to be of overriding importance in determining whether or not macrophyte diversity at an individual site is depressed below the optimal level within a given geographical region (e.g. Baattrup‐Pedersen, Szoszkiewicz, Nijboer, O'Hare, & Ferreira, ; Bando et al., ; Chappuis et al., ; Kennedy et al., ; Lang & Murphy, ; Morandeira & Kandus, ; Rolon & Matchik, ; Schneider et al., ; Tapia Grimaldo et al., ). Physical size of individual rivers, however, seemed to be of little importance in influencing α‐diversity.…”

“…Recently, there has been a major effort to improve understanding of the drivers of biogeographical distributions and diversity of freshwater macrophyte species, some (but by no means all) of which have broad planetary distributions (e.g. Alahuhta et al., ; Bornette, Amoros, & Lamouroux, ; Carvalho, Bini, Diniz‐Filho, & Murphy, ; Chappuis, Ballesteros, & Gacia, ; Chappuis, Gacia, & Ballesteros, ; Heikkinen, Leikola, Fronzek, Lampinen, & Toivonen, ; Kennedy et al., , ; Lang & Murphy, ; Makkay, Pick, & Gillespie, ; Morandeira & Kandus, ; Murphy et al., ; Ranieri, Gantes, & Momo, ; Redekop, Hofstra, & Hussner, ; Santamaría, ; Tapia Grimaldo et al., ). Most of these studies have examined macrophyte diversity and distributions in cool‐temperate river and lake systems, with least attention being paid to warm‐water river macrophyte communities.…”

Niche-breadth of freshwater macrophytes occurring in tropical southern African rivers predicts species global latitudinal range

“…There exists a large, and long-standing, published body of data for river macrophytes dealing with species range and relationships with spatial and environmental factors, in both tropical and temperate conditions, against which at least some of the detail of our findings for the ecology of Zambian riverine macrophyte species can be compared (e.g., Butcher, 1933;Ferreira and Moreira, 1999;Baattrup-Pedersen et al, 2006;Lang and Murphy, 2012;Varandas Martins et al, 2013;Chappuis et al, 2012;Kennedy et al, 2015;Tapia Grimaldo et al, 2016). However, only a few studies have hitherto examined niche-breadth in aquatic macrophytes, and all but one (Fu et al, 2015: on riverine wetland plants) have dealt solely with temperate lentic waterbodies.…”

“…It also has implications for our understanding of how such plant − environment interactions may change in response to largescale human impacts upon river ecosystems. For example, recent work on macrophyte communities in hardwater rivers (>10 mg L −1 CaCO 3 concentration) has shown that spatial, as well as environmental, variables help explain macrophyte diversity at both global and regional scales (Tapia Grimaldo, 2013;Tapia Grimaldo et al, 2016). Improved knowledge of the niche-characteristics and nichebreadth of macrophyte species may improve our ability to predict how freshwater macrophytes will respond, at large scales, to likely future challenges affecting their ecology.…”

Climatic niche shift of aquatic plant invaders between native and invasive ranges: a test using 10 species across different biomes on a global scale

“…The resulting eight bioclimatic variables represent numerous factors, including general trends (means), variation (seasonality), and limiting variables (minimum and maximum temperatures) and are closely related to both distribution and physiological performance of plant species (Tab. S2; Grimaldo et al, 2016).…”