Diversity and distribution of odonates in Rani Reserve Forest, Assam, India

Odonata are the bioindicators of freshwater ecosystem health and is recognised as an excellent ‘flagship’ group among insects. Baseline knowledge on the diversity and distribution of odonates over spatiotemporal scale is the key to biodiversity conservation. Rani Reserve Forest of Assam is a mosaic of all the habitat types suitable for odonates. The present work aims at studying the diversity and distribution of Odonates in Rani Reserve Forest. The study was carried out from December 2014 to November 2017 by categorising the study area into three major habitat types: 1. lentic system, 2. lotic system and 3. terrestrial woodland. A total of 67 species belonging to 44 genera, representing 11 families were recorded. First published records of three species, Onychothemis testacea (Libellulidae), Philoganga montana (Philogangidae) and Indocnemis orang (Platycnemididae) from the state are also provided herewith. Species richness was the highest in lentic system whereas recorded the lowest in running waters of larger forested streams. Shannon diversity index also indicated that the lentic system is relatively diverse (2.95) and smaller streams of the lotic system showed the highest species evenness (0.87). Libellulidae (43%) was found to be the most dominant family belonging to suborder Anisoptera followed by Coenagrionidae (22%) of suborder Zygoptera. Philogangidae (1%) recorded the lowest number of species. Taxonomically related species showed distinct ecological segregation within these different habitat types occupying different microhabitats therein.

Periphytic diatoms from an oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil

Knowledge of biodiversity in oligotrophic aquatic ecosystems is fundamental to plan conservation strategies for protected areas. This study assessed the diatom diversity from an urban reservoir with oligotrophic conditions. The Piraquara I reservoir is located in an Environmental Protection Area and is responsible for the public supply of Curitiba city and the metropolitan region. Samples were collected seasonally between October 2007 and August 2008. Periphytic samples were obtained by removing the biofilm attached to Polygonum hydropiperoides stems and to glass slides. The taxonomic study resulted in the identification of 87 diatom taxa. The most representative genera regarding the species richness were Pinnularia (15 species) and Eunotia (14 species). Five species were registered for the first time in Brazil and seven in the State of Paraná. Taxonomic and ecological comments of the species registered are provided.

Biological parameters of Pseudocurimata boulengeri (Characiformes: Curimatidae) inhabiting the Chongón dam, Ecuador

Pseudocurimata boulengeri is an endemic species of Ecuador, which sustains a large group of fisher families. The biological data of this species correspond to reports from lotic systems of Los Ríos province; nevertheless, their trend in a lentic system is not yet known. This paper describes the sex ratio, length-weight relationship, gonad development, spawning season and size at reproductive maturity of P. boulengeri, inhabiting the lentic system of Chongón dam, Ecuador. Fish were caught between 2003 and 2009 using gill nets (2.5"). The total length (Lt) of caught specimens ranged from 10.5 to 35.5 cm, spawning occurred between the months of October and March, and size at first maturity for females was estimated at 17.9 cm (Lt) and 20.0 cm (Lt) for males. Between May and October male and female ratios were as expected (1:1), whereas for May, November and April, females ratios were higher than males, situation that coincided with the spawning season. The limnetic conditions and high production characteristics of Chongón dam, have promoted the availability of a great amount of food for this species, which may have allowed P. boulengeri to have a more extended reproductive season in this favorable environment.

Invertebrate Colonization During Leaf Decomposition of Eichhornia azurea (Swartz) Kunth (Commelinales: Pontoderiaceae) and Salvinia auriculata Aubl. (Salvinales: Salvinaceae) in a Neotropical Lentic System

The decomposition of macrophytes is an essential process for cycling of carbon and nutrients, and it is source of organic matter for invertebrates in lakes. We evaluated the colonization by aquatic invertebrates in decomposing leaves of two species of macrophytes in a Neotropical lentic system. The experiment was conducted from November 2007 to February 2008, with the use of 54 litter bags (Eichhornia azurea (Swartz): n = 27 and Salvinia auriculata Aubl.: n= 27), each containing 10 g of dry leaves. Three bags of each species were retrieved after 2, 4, 8, 12, 24, 36, 48, 60 and 72 days of incubation. The remaining leaf mass of the two macrophytes species tended to decrease with time, although at different rates. The decomposition of E. azurea and S. auriculata leaves were classified as rapid and intermediate, respectively. In general, during the experiment carbon: nitrogen ratio declined in E. azurea and increased in S. auriculata, and presented difference among the days of the experiment and between the macrophyte species. In E. azurea mass loss was negatively correlated with carbon: nitrogen ratio of the leaves, but the same pattern was not observed for the S. auriculata leaves. The composition and richness of invertebrates differed among days, but not between macrophytes species. We concluded that the succession process along the detritus chain was more important in structuring the invertebrate community than the variation in the nutritional quality of the leaf litter for these two species of macrophytes.Colonização por Invertebrados Durante a Decomposição foliar de Eichhornia azurea (Swartz) Kunth (Commelinales: Pontoderiaceae) e Salvinia auriculata Aubl. (Salvinales: Salvinaceae) em um Sistema Lêntico NeotropicalResumo. A decomposição de macrófitas é um processo essencial para ciclagem de carbono e nutrientes, e é fonte de matéria orgânica para invertebrados em lagos. Avaliamos a colonização por invertebrados aquáticos em folhas em decomposição de duas espécies de macrófitas em um sistema lêntico Neotropical. O experimento foi conduzido entre novembro de 2007 e fevereiro de 2008, com a utilização de 54 sacos de detrito (Eichhornia azurea (Swartz): n = 27 e Salvinia auriculata Aubl.: n = 27), cada um contendo 10 g de folhas secas. Três sacos de cada espécie foram recuperados após 2, 4, 8, 12, 24, 36, 48, 60 e 72 dias de incubação. A massa remanescente de folha das duas espécies de macrófitas tendeu a diminuir com o tempo, embora a velocidades diferentes. A decomposição de folhas de E. azurea e S. auriculata foram classificadas como rápida e intermédia, respectivamente. Em geral, durante o experimento a razão carbono: nitrogênio diminuiu em E. azurea e aumentou em S. auriculata, e apresentou diferença entre os dias de experimento e entre as espécies de macrófitas. Em E. azurea perda de massa foi negativamente correlacionada com a razão de carbono: nitrogênio das folhas, mas o mesmo padrão não foi observado para as folhas de S. auriculata. A composição e riqueza de invertebrados diferiram entre os dias, mas não entre espécies de macrófitas. Concluímos que o processo de sucessão ao longo da cadeia de detritos foi mais importante na estruturação da comunidade de invertebrados do que a variação na qualidade nutricional do detrito de folha para estas duas espécies de macrófitas.