Aquatic plant diversity of lakes around Gondia city, Maharashtra, India

Gondia is one of the centrally located districts of India. It is famous for its lakes and water bodies. These water bodies exhibit enormous diversity of plants according to geographical location, depth of water body, water regime, chemistry of water, soil and sediment characteristics. Very little work has been done so far on the flora of the water bodies of Gondia district. Therefore, a study has carried out to understand the aquatic plants diversity of selected 5 lakes around Gondia city. For this, well-planned surveys were carried out at selected sites frequently. During visits, data like habit, life span, local names, and life forms of all the plant species present in the water body were collected. During the study, 44 species of 37 genera belonging to 26 families have been recorded from selected sites. Most dominant family was Hydrocharitaceae with 4 genera and 4 species, followed by Asteraceae, Poaceae, Convolvulaceae and Potamogetonaceae with 3 species each. Jaccard and Sorenson similarity indexes showed that Lake I and Lake II have maximum similarity and highest diversity as compared to other sites. The present work revealed the database of aquatic plants in water bodies around Gondia, which will help in future work for the conservation, preservation and growth of the local biodiversity.


INTRODUCTION
Gondia is a north-eastern border district of Maharashtra state, connected with Chhattisgarh on the eastern side and Madhya Pradesh towards Northern side. Geographically, it is in the centre of India and spread over the area of 5859 km 2 , out of which 2833 km 2 are under forest cover. Gondia is important from the biodiversity point of view as it is a site of two protected areas, i.e. Navegaon Bandh National Park and Nagzira Wildlife Sanctuary. Gondia is also famous for its lakes and ponds, therefore it is considered as the lakes district of Maharashtra. One wellknown Navegaon Bandh lake with wetland is present in the district. Likewise, every village and town of this district has its own lake or water body. Restoration and recharge of water table is possible due to the lakes, thus the lakes play an important role in our lives [1]. These water bodies or wetlands exhibit enormous diversity of plants according to geographical location, depth of water body, water regime, chemistry of water, soil and sediment characteristics [2]. Moreover, these water bodies are an integral component of the daily life activities of rural people for their survival, and hence these ecosystems are more vulnerable to eutrophication because of the anthropogenic activities [3]. All these things lead variation in the aquatic plant diversity of water body, which ultimately affects water retaining capacity of wetland day by day.
The researches on aquatic plants have started gaining importance, as they are part of biodiversity. Moreover, they are an important source of food, fodder, herbal medicine and domestic household materials for the people living in its vicinity. There are many aquatic plants which produce corms and rhizomes which are used for an edible purposes in many rural areas. They are also important components of lentic ecosystems. Various researchers have carried out surveys on such aquatic plants in different water bodies across India [4 -6]. Aquatic plants provide food, oxygen, shelter and breeding place for aquatic animals and maintain the integral balance of the ecosystem [7,8]. Studies on aquatic plants, especially their ecology, were few in number before 1960s [9]. But, thereafter several studies relating to aquatic and wetland flora have been carried out by many researchers throughout the world, including various parts of India [10 -15].
Kumar and Chelak [12] studied macrophytic diversity in ponds of Dongargarh city of Chattisgarh and compared their observations with the study conducted earlier and concluded that macrophyte assemblages are changing and are dynamic in different ponds. Two RET (Rare, Endangered and Threatened) species viz. Wolffia arrhiza and Lindernia anagallis of Araceae and Scrophulariaceae family respectively were documented from Gadakharad lake by Dalasingh et al. [16]. Chen et al. [17] also reported that several hydrophyte families, which were not listed on the Red List of China, have been severely threatened in Japan; they also suggested a comprehensive evaluation of the status of hydrophytes in China. It indicates that for conservation measures to be enacted, it is necessary to describe the actual status of aquatic species; however, the distribution data on aquatic macrophyte flora, which is the most basic information necessary for the threatened species, are relatively limited. For example, no floristic data have been obtained for more than 19 major and hundreds of minor lakes found in Gondia district. Hence, present study has been conducted to understand aquatic plant diversity of 5 selected water bodies of Gondia district.

Study Site
Gondia district is situated at 80.1961 0 E longitude and 21.4549 0 N latitude. For the study of aquatic plants, 5 sites were selected around Gondia city and a survey was carried out during the months of July 2019 to February 2020. The selected lakes were Katangi kala (henceforth referred to as Lake I), Lohara (henceforth referred to as Lake II), Fulchur (henceforth referred to as Lake III), Pangdi (henceforth referred to as Lake IV), and Karanja (henceforth referred to as Lake V) (Table 1, Figure 1).  Figure 1. Satellite images of selected sites: Lake I [19], Lake II [20], Lake III [21], Lake IV [22] and Lake V [23] Collection of aquatic plants where is: SJ -Jaccard's similarity coefficient, a -number of species in both sites, b -number of species absent in A but present in B, cnumber of species present in A but absent in B.
The above aquatic plant data was also analysed by Sorensen's similarity index (SSI) [29]. This measure is very much similar to Jaccard's measure: where is: SS -Sorensen's similarity coefficient, a -number of species in both sites, b -number of species absent in A but present in B, cnumber of species present in A but absent in B.

RESULTS AND DISCUSSION
A total 44 species of aquatic plants representing 37 genera belonging to 26 families have been recorded from the selected 5 sites. Out of these, 41 species of 34 genera covering 24 families were Angiosperm, 2 species of 2 genera representing 1 family were Algae and 1 species of 1 genera representing 1 family was Pteridophyte. Amongst the Angiosperm, 24 dicot species belong to 19 genera and 14 families and 17 monocot species belong to 15 genera and 10 families were found ( Figure 2).

Figure 2. Distribution on the basis of plant types
During the study, 32 genera were represented with single species, 4 genera by 2 species each and 1 genera by 3 species (Table 2). Hydrocharitaceae were found to be the most observed family with 4 genera and 4 species, followed by Asteraceae, Poaceae, Convolvulaceae and Potamogetonaceae with 3 species each. Families like Amaranthaceae, Characeae, Lythraceae, Menyanthaceae, Onagraceae, and Scrophulariaceae were represented by 2 species each and all the remaining families were represented by 1 species only (Tables 2 and 3 and Figure 3). Lakshmanan and Gathi [4] also reported the dominance of Hydrocharitaceae, Poaceae along with Convolvulaceae family in selected wetlands of Tamilnadu.   The plant diversity is a strong bio-indicator for lake ecosystems differed in types and response [30]. The aquatic plant species diversity of 5 lakes was found to be healthy as Pistia strtiotes was the only invasive alien plant found there. Lake II had the highest number of species (35 spp.), followed by Lake III (28 spp.), Lake I (22 spp.), Lake V (20 spp.) and Lake IV (15 spp.). A total of 35 aquatic plant species (80 % of the total recorded species) were confined only to Lake II, out of the 5 lakes. On the other hand, Lake IV and V had the lowest number of confined species ( Figure  4).
It has been observed by Kohtaroh et al. [10] that floristic diversity of any pond depends upon some factors like size, depth or shallowness of the water body, sediment deposition, seed sources, as well as the recent history of the water body regarding any type of excavation. Boyra and Patralekh [31] also reported that aquatic plants occur mainly in the shallow regions of lakes, ponds or any water body. In the present study, a clear pattern is observed, in which the plant species coverage increased when the depth of lake decreased. It indicates that aquatic plant diversity of Lake IV (15 plant species) is negatively correlated with the lake surface area and depth, whereas Lake II (35 plant species) showed positive correlation with the lake surface area and depth as compared to rest of the lakes (Tables 1 and 4 and Figure 4). Different areas of a lake can have water depths variation because of the diverse topography of the lake bottom. Depth plays a very important role in the growth of aquatic plants, as the factors like water transparency, water temperature, availability of light, and light regime have effect on it [32]. Changes in all of these factors can affect the growth and distribution of submerged plants and structure of communities [33]. There are many reports which showed effects of water depth on the growth of the submerged species Myriophyllum spicatum [  Lake I, II and III are seasonal i.e. they carry water for 8 -9 months of a year, while Lake IV and V store water throughout year (Table  1). Hence, grazing by domestic cows and buffaloes are observed around Lake I, II and III during certain periods of the year which may increase the plant diversity. This result is in accordance with hypothesis concerning the role of disturbances and productivity in biodiversity [40,41]. In addition to these, some anthropogenic activities, like fishing, could also be the reason behind variation in aquatic plant diversity in selected lakes. Fishing is carried out in Lake IV and V in most of the part of year which is not found in Lake I, II and III.  Vallisneria spiralis -+ + -+ 3 L+F, F+Z, L+Z K -Lake I, L -Lake II, F -Lake III, P -Lake IV and Z -Lake V Figure 5. Some plants recorded from selected 5 sites The inconsistent water depth of the lakes leads to the growth of various species in a specified micro habitat. The collected aquatic plants of these lakes can be classified into different micro-habit groups [43]. Among the total collected plants, 21 (48 %) species belong to the emergent type followed by 11 (25 %) species of the rooted floating type, 8 (18 %) species of the rooted-submerged, and 4 (9 %) species of the free floating type. If observed based on the distribution by lakes, the emergent plants were equally distributed in all lakes, however, the rooted floating and free floating plants were found in negligible numbers in Lake IV and V which are deeper than the other lakes. Submerged plants were also observed in similar numbers in all the lakes (Table 1, Figure 6).
As per the Jaccard's similarity index, Lake I and II have maximum similarity (0.58 %) and highest diversity as compared to other sites.
The sites Lake I and V, Lake II and III, Lake III and V showed equal similarity (0.50 %), but they are less diverse than Lake I and II. The lowest similarity index was observed in Lake II and IV (0.28 %) and Lake III and IV (0.30 %), indicating lesser diversity. Sorenson's similarity index has also given the same observation that Lake I and Lake II have more similarity (0.73 %) and higher diversity, while Lake II and Lake IV indicated low similarity (0.44 %) and less diversity. As per Sorenson's coefficient, lake combinations like I and III, I and IV, II and III, II and V, III and V, IV and V showed similarity index in the range between 0.60 to 0.66 % (Tables 5, 6 and 7).