Freshwater Reptile Persistence and Conservation in Cities: Insights from Species Occurrence Records

water Article Freshwater Reptile Persistence and Conservation in Cities: Insights from Species Occurrence Records Eren Turak 1,2,* , Alex Bush 3, Jocelyn Dela-Cruz 1 and Megan Powell 1 1 Environment, Energy and Science Group, NSW Department of Planning, Industry and the Environment, 4 Parramata Square, Parramatta, NSW 2150, Australia; [email protected] (J.D.-C.); [email protected] (M.P.) 2 Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences UNSW, Kensington 2052, Australia 3 Lancaster Environment Centre, Lancaster University Library Avenue, Lancaster University, Lancaster LA1 4YQ, UK; [email protected] * Correspondence: [email protected] Received: 25 October 2019; Accepted: 24 February 2020; Published: 28 February 2020 Abstract: Reptiles are rarely included in urban freshwater biodiversity monitoring and conservation. We explored the global persistence of freshwater dependent turtles, lizards, crocodilians and snakes in cities with a population greater than 100,000 using species occurrence data in online databases from a five-year period (2013–2018). We then used ecological niche models to help identify the locations of suitable habitats for three freshwater reptile species in Sydney, Australia. Our Global analysis showed that sightings of a majority of known species of crocodilians and freshwater turtles were recorded in databases within this 5-year period in contrast to about one in three freshwater lizard species and one in ten freshwater snake species and that freshwater reptiles were observed within 50 km of the center of 40% of the 3525 cities. While global databases hold substantial recent species occurrence records for some regions, they contain very little data for large parts of the world. Modelling showed that potential suitable habitat for the three freshwater species in Sydney was distributed across areas with different levels of urban development. The persistence of populations of freshwater reptiles in and around a large proportion of the world’s cities show that this group can play an important role in urban biodiversity conservation. Keywords: online databases; urban ecosystems; freshwater biodiversity; reptiles; ecological niche models 1. Introduction The number of people living in cities is expected to reach 6.3 billion by 2050, representing an increase of 62% from 2014 [1]. Importantly the growth of urban populations between 2000 and 2030 is expected to be around 70%, while the growth of urban land cover in the same period is expected to be 200% [2]. One implication of these predictions is that biodiversity conservation in cities will play an increasingly important role in protecting and restoring earth’s biodiversity in the 21st century. The two main strategies for optimizing biodiversity in cities are: designating areas that are exclusively reserved for nature and planning how other parts of the urban environment can be shared between human populations and nature [3]. It is also important to understand the food, habitat and connectivity requirements of different species. Freshwater reptiles are typically dependent on components of both aquatic and terrestrial environments. This could make them either more vulnerable or more resilient to a specific threat compared with strictly aquatic or strictly terrestrial species. Hence, the persistence of freshwater reptiles in cities can provide very useful information on the status of urban ecosystems. Water 2020, 12, 651; doi:10.3390/w12030651 www.mdpi.com/journal/water Water 2020, 12, 651 2 of 16 In some climatic zones monitoring freshwater reptiles can complement the well-established and widely used indicators of freshwater ecosystem health, e.g., macroinvertebrates [4], fish [5] and diatoms [6], and of terrestrial ecosystems, e.g., birds [3], but this potential has not yet been explored at a global scale. Having agreed criteria and species lists for reptiles that depend on freshwater ecosystems could help guide management actions aimed at improving freshwater biodiversity. The first global attempt to assess species richness and endemism of freshwater reptiles was under the Freshwater Animal Diversity Assessment (FADA) [7]. In that program Freshwater species included: “real aquatic” species, which accomplish all or part of their life cycle in water, and “water-dependent” or “paraquatic” species, which show close and specific dependency on aquatic habitats [7]. Limno-terrestrial species, which require an aqueous matrix in strictly terrestrial habitats, were not considered freshwater species [7]. Freshwater species, hence, include all inland aquatic and paraquatic species as well as some species that live in marine and estuarine environments but show a genuine tolerance to freshwater [7]. Many species included in FADA lists, however, present special cases that do not neatly fit into these definitions. These special cases were addressed by experts in papers on individual groups [7]. Some of the FADA papers included very clear definitions of what constitutes a freshwater species within a specific group but others were less definitive. For example, freshwater birds were defined as species for which disappearance of a freshwater habitat would lead to the disappearance of the species with little chance to adapt [8]. The definition used to attribute 73 lizard species to freshwater was more operational: “lizard species which, on the basis of literature records, and our own observations, appear to be partly dependent on freshwater habitats or resources for their existence” [9]. None of the lizard species were considered strictly aquatic [9]. Similarly, all 23 species of the order Crocodilia were considered semi-aquatic and were listed as freshwater species, including the Saltwater Crocodile, Crocodylus porosus [10]. Many freshwater species of snakes belong to genera, which also include marine or terrestrial species [11] and many morphological specializations seen in freshwater snake species have also been observed in strictly terrestrial or strictly marine snake species. Comprehensive biological information that could confirm freshwater habit was lacking for many species and genera of snakes, hence, the proposed list of 153 freshwater snakes was considered provisional [11]. The list of freshwater turtle species provided for FADA [12] was not accompanied by a precise definition of a freshwater turtle. The 257 Freshwater turtle species included in the FADA list were in 79 genera. Typical environments listed for several of these genera included terrestrial environments but no marine habitats [12]. Since the initial publications in 2008, there have been several unpublished revisions of the FADA lists of lizards, snakes and turtles, resulting in a greater number of freshwater species in all three groups (Aaike DeWever pers. comm, May 2018). Distinguishing freshwater species from marine and terrestrial species helps to prioritize species in conservation activities focused on freshwaters. Hence, this classification is useful provided it is recognized that (1) there are probably large differences between major reptile groups i.e., snakes, lizards, turtles in the nature of dependency of species on freshwater; and (2) degree of dependence on freshwater or any type of aquatic environment can vary greatly among species within a genus [9,11] or even among age groups within a population of one species [12]. While current lists of freshwater snakes, lizards and turtles will continue to be refined, they are probably adequate for freshwater biodiversity assessments at broad spatial scales in most parts of the world. The objectives of making cities more livable and optimizing their contribution to regional and global biodiversity conservation can be helped by applying principles of systematic conservation planning [13] in urban planning. Special considerations for freshwater will be necessary [14] and may include the use of wetland, river and aquifer types [15], or mapping likely suitable habitat for individual species [16] or a combination of these, as surrogate features. Ecological niche modeling for freshwater reptile species can help identify the locations of likely suitable habitat for these species [17]. These locations can be included in surrogate features for spatial prioritization of conservation actions focused on freshwater ecosystems [16] and to design monitoring programs for assessing the status of freshwater reptile populations in cities. Water 2020, 12, 651 3 of 16 We predict that, despite the multiple threats they face in urban environments, freshwater reptile species persist in and around a large proportion of cities. A larger number of freshwater reptile species would be expected in and around cities located in tropical and subtropical regions, especially in South and Central America and South East Asia where overall freshwater reptile diversity is high [9,11]. We expect that current global geographic patterns of freshwater reptile persistence in cities will be reflected in recent species occurrence records available from online databases. Where there are such populations in or near cities, important conservation gains should be possible by careful urban planning that supports specific actions to protect and restore freshwater reptile habitats. The success of these actions depends on the availability of potential habitat, ecology of the reptile species and likely support from communities and governments. We expect that ecological niche modelling techniques

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