Diversity and structure of turtle assemblages: associations with wetland characters across a floodplain landscape

We studied 24 wetlands along a 296‐km portion of the lower Missouri River floodplain, USA during 1996–1998. Our goal was to examine relationships between wetland characters and freshwater turtle diversity. We collected data on a total of 2201 individual captures of six freshwater turtle species. Ten species variables (richness, evenness, proportion of lentic species combined, proportion of lotic species combined, and proportions of six individual species) described the turtle assemblage structure and were associated with six broad wetland categories (remnant oxbow, remnant slough, connected scour, isolated scour, temporary farmed, and temporary not farmed) as well as with six abiotic (water depth, distance from the river, duration dry, duration flooded, size, and turbidity) and two biotic (primary and secondary productivity) wetland characters. Repeated‐measures MANOVA and ANOVA revealed highest diversity in remnant sloughs and oxbows as well as in newly created scour wetlands and lowest diversity in temporary wetlands. Multiple regressions and correlations indicated that the single most important wetland characteristic for high turtle diversity was a low annual duration of drying. Oxbows supported the highest proportions of lentic turtles; while connected scours supported the highest proportions of lentic turtles. Lentic species proportions were highest in wetlands that were frequently flooded, relatively distant from the Missouri River, and insect rich, while lotic species proportions were highest in wetlands that were turbid, close to the river, and relatively insect poor. The cohabitation patterns of several turtle species suggest that direct or indirect interactions between species may affect assemblage structure. Based on our broad array of wetlands, we identified crucial wetland types and characteristics that were associated with maximum diversity for freshwater turtles. Empirical studies similar to ours across broad landscapes are needed for a variety of wetland floral and faunal groups before sound conservation and management recommendations can be formulated.     

Impacts of river alteration for flood control on freshwater turtle populations

The impacts of artificial river alteration for flood control on the dynamics of freshwater turtle populations were studied in small urban and rural river systems in northwestern Chiba Prefecture, Japan, from 2003 to 2006. The population density of the Reeve’s turtle, Chinemys reevesii, decreased markedly, from 279 turtles km⁻¹ in 2003 to 43 turtles km⁻¹ in 2006 in association with the artificial river alteration practices implemented by 2006. Low turtle population densities in other river sections where flood control measures have already been implemented suggest slow population recovery. River alteration practices also altered the age structures, sex ratios, and demographic characteristics of the turtle populations, although the exact consequences for population viability have not yet been determined. Because the turtles select concave submerged riverbanks or bottoms with slow or no current velocity, increased current velocity in the altered river section make the entire riverbank and bottom unsuitable for hibernation. Overall, river alteration for flood control during the winter season when turtles are inactive due to low water temperature negatively impacted freshwater turtle populations.     

The ecology and morphology of Australia's desert turtle (Emydura macquarii emmotti)

Cooper Creek is one of Australia's largest unregulated river systems and one of the world's most variable large river systems. It is a dynamic environment that oscillates between booms and busts; yet, many species thrive in it. One of these species, the Cooper Creek turtle (Emydura macquarii emmotti) has received little attention, despite being one of Australia's largest freshwater turtles and living further inland than any other Australian turtle. We conducted surveys for E. m. emmotti in 2001–2004, 2019, and 2022, focussing predominantly on the Waterloo waterhole. Waterloo had a large population of E. m. emmotti (508 estimated individuals; 95% CI = 447–596) with an estimated density of 64.8 turtles/ha (95% CI = 57.0–76.2) and estimate biomass of 74.4 kg/ha (95% CI = 57.6–100.3 kg/ha). Juveniles were highly abundant in all years, representing up to 63.6% of captured individuals. It was slightly (but not significantly) male-biased in 2001–2004 and significantly female-biased in 2019. All sizes and sexes used the floodplain during a flooding event in 2022, but more males than females were captured on the floodplain, and there was evidence of male-biased dispersal across the years. Compared to Murray River turtles (Emydura macquarii macquarii), E. m. emmotti exhibited megacephaly across all ages and sexes, with particularly pronounced megacephaly in adult females. Algae were present on many individuals (including on the skin and plastron) but was relatively more abundant on juveniles. Leeches were not detected on any of the 66 turtles that were examined for them. The following injuries/malformations were noted: missing or injured limbs (3.2%), missing or injured eyes (1.3%), damaged shells (8.0%), scute/shell anomalies and malformations (10.6%), and marginal scute seams extending into the costals (67.4% of adults, 1.2% of juveniles). This paper presents some of the first work on this unusual turtle and makes recommendations for future research.     

Great Lakes coastal wetland habitat use by seven turtle species: influences of wetland type, vegetation, and abiotic conditions

Great Lakes coastal wetlands are important habitats for turtles but few studies have looked at factors driving community structure in these systems. We evaluated the effects of wetland type, vegetation, and abiotic conditions on turtle communities for 56 wetlands in Lakes Huron, Michigan, and Superior with data collected during the summers of 2000–2008. Overall, 1,366 turtles representing seven species were captured using fyke nets. For the majority of species, catches were highest in drowned river mouth wetlands In addition, turtles tended to be more abundant in water lilies, submersed aquatic vegetation, and cattails compared to bulrush. We also found positive correlations between catches of four of the species as well as total turtle catch and turtle species richness with a human disturbance gradient. These correlations suggest that turtles may be able to utilize coastal wetland areas that are inhospitable to fish because of hypoxic conditions. Our results show the importance Great Lakes coastal wetlands to turtles, and stress the need for managers to take into account turtle populations when preparing conservation and restoration strategies.     

Microhabitat Association of Blanding's Turtles in Natural and Constructed Wetlands in Southeastern New York

ABSTRACT We studied Blanding's turtle (Emydoidea blandingii) microhabitat in natural wetlands and wetlands constructed for the turtles in Dutchess County, New York, USA. Investigation of these topics can provide information on ways to increase the extent of Blanding's turtle habitat, improve its quality, and assure that conservation or restoration managers do not overlook key habitat characteristics. Microhabitat was determined by radiotracking individuals to their exact locations and recording habitat variables. Blanding's turtles were associated with shallow water depths (x̄ = 30 cm), muck substrates, and areas of abundant vegetation (total cover xM = 87%). Buttonbush (Cephalanthus occidentalis)had the greatest mean total cover (29%). In the constructed wetlands, Blanding's turtles were associated with significantly less cover and warmer water than in the natural wetlands. Blanding's turtles appeared to be using the constructed wetlands to bask and forage in the spring and early summer but moved to deeper wetlands in late summer when the constructed wetlands dried up or became too warm. For Blanding's turtles, new habitat should contain abundant emergent vegetation (including buttonbush in Dutchess County and other areas where the turtles are known to use buttonbush swamps), basking areas, muck, floating plant material, and submerged aquatic vegetation. Blanding's turtle's use of constructed wetlands highlights the value of a complex of connected wetland habitats in providing for the varied needs of the turtle.     

Climate change affects the early-life history of a freshwater turtle in a severely drying region

Freshwater turtles are one of the most threatened vertebrate groups. Climate change is a major threat to these species, with impacts affecting all life-history stages. There is currently a limited understanding of how changes in climate may alter the environmental triggers for hatching and emergence from the nests of freshwater turtle hatchlings. This precludes making predictions about how climate change may impact freshwater turtle recruitment success. The southwestern snake-necked turtle (Chelodina oblonga) is endemic to south-western Australia, a global biodiversity hotspot that has undergone severe climatic drying. Recruitment failure is thought to be occurring in many populations of the species. However, there is little understanding as to how environmental change may be influencing recruitment. This study aimed to: (1) determine the incubation duration and hatching and hatchling emergence success of C. oblonga, (2) determine if the species exhibits hatching or emergence synchrony and/or delayed emergence and (3) quantify the effects of temperature and rainfall on hatchling emergence. Using this information, the study assesses how climatic drying and warming may be impacting C. oblonga's early life-history. Between 2018 and 2020 nest sites were monitored around a large urban wetland with weekly assessments of egg and hatchling status. Incubation duration and hatching and hatchling emergence success were calculated, and generalized linear models were built to determine how temperature and/or rainfall predicted emergence. Hatchlings either emerged shortly after hatching or overwintered in the nest, and both hatching and emergence were asynchronous. Both emergence periods were positively associated with temperature and rainfall. This study reveals that incubation duration, hatching success, hatchling emergence and survival are all likely to be impacted by recent and projected climate change, and especially drying. Warming and drying are predicted for many temperate regions globally, and it is therefore important that their impacts on the early life history of freshwater turtles be better understood.     

The diet and digestive energetics of an Australian short-necked turtle, Emydura macquarii

We described the diet of Emydura macquarii, an omnivorous turtle from south-eastern Australia, compared its digestive performance on diets of fish or plants at two temperatures, and related how both diet and temperature affect its food selection in nature. Filamentous algae constituted 61% of the stomach content of E. macquarii. The turtles rarely fed on motile prey, but selected carrion from the lagoon bottom and terrestrial insects (Diptera, Hymenoptera and Coleoptera) trapped on the surface of the water. Digestive efficiency of E. macquarii was affected little by body temperature, in contrast to consumption rates and rates of passage which were strongly influenced by both temperature and diet. In combination, these responses resulted in a slower rate of digestion at 20°C than at 30°C. Digestive efficiency of E. macquarii on a herbivorous diet at 30°C (49%) was about half that of turtles on a carnivorous diet (91%), but they had longer transit times (118 h on the plant diet versus 70 h). Lower consumption rates and longer mean retention times in turtles fed plants compared those fed fish relate to slower digestive processing of the plant. Rapid processing and higher consumption rates of fish by E. macquarii resulted in higher energy gains compared to turtles consuming plants (almost 100 times more energy at 30°C). The laboratory results suggest that fish carrion and aquatic and terrestrial invertebrates are probably essential dietary items of E. macquarii in the wild, because its metabolic requirements cannot be met from aquatic macrophytes alone.     

Road density and wetland context alter population structure of a freshwater turtle

Roads are detrimental to wildlife populations that require contiguous networks of terrestrial and aquatic habitats. Many species of freshwater turtles are sensitive to habitat fragmentation caused by roads, and are susceptible to road mortality during overland migrations. The common long‐necked turtle (Chelodina longicollis) is an Australian freshwater turtle that frequently moves between wetlands, and so populations may incur negative impacts from road effects. Here, we assessed the relationship between C. longicollis and road density and landscape variables within populations inhabiting 20 wetlands distributed throughout greater Melbourne, Australia. The size frequency distribution of C. longicollis at sites surrounded by high road densities was skewed towards larger individuals, but there was no difference in the frequency of juveniles between high and low road density sites. Regression modelling revealed a clear positive relationship between road density and carapace length (CL) of C. longicollis; the mean CL at a site with the highest road density was predicted to be 23% greater than mean CL at a site surrounded by no roads. Female CL was also positively related to road density. There was a clear positive relationship between wetland age and CL, although this relationship was not as strong. While there was no relationship evident between road density and the proportion of female C. longicollis at a site, more females were captured at smaller ephemeral sites surrounded by a high proportion of green open space and located near drainage lines. We did not find evidence of sex‐related differences in road effects. These results suggest that roads may be affecting C. longicollis in the study area, but the direct cause of any effects is difficult to identify.     

Terrestrial activity,movements and spatial ecology of an Australian freshwater turtle,Chelodina longicollis,in a temporally dynamic wetland system

Animal movements, use of space, activity patterns and habitat use are in part determined by proximal factors such as the landscapes they occupy, seasonal or environmental cues and individual attributes such as sex and body size. Using radio‐telemetry and a drift fence, we examined the contribution of these factors to variation in movements, use of space and terrestrial activity in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae), in south‐east Australia. Movements and use of space depended strongly on landscape attributes, while sex and body size were less important. Movements and use of space also varied seasonally and were partly correlated with rainfall. The high overall vagility of turtles, irrespective of sex and adult body size (13.8 ± 2.8 ha (±SE) home range, 2608 ± 305 m total distance moved, 757 ± 76 m range length), probably reflects a common need to be mobile in a landscape characterized by fluctuating resources in temporary wetlands. Use of temporary wetlands also drives C. longicollis into terrestrial habitats for movements between wetlands and extended refuge. Timing of inter‐wetland movements was associated with rainfall, but most notably for immature individuals and for those moving towards temporary wetlands. Movements of adults, evacuation of the drying wetland and periods of extended refuge (i.e. aestivation) were less dependent upon rainfall if at all. We conclude that movements about and use of the landscape by C. longicollis are under the strong influence of several interacting factors such as patch configuration, seasonal and environmental cues, and in part, body size. We argue that such behaviours are also ultimately under selection from the costs and benefits of these behaviours in the context of fluctuating resources.     

Seasonal and diel dive performance and behavioral ecology of the bimodally respiring freshwater turtle <Emphasis Type="Italic">Myuchelys bellii</Emphasis> of eastern Australia

Freshwater turtles have an extraordinary physiological ability to endure dive times that can range from days to months using aquatic respiration. In cryptodires (e.g., white-lipped mud turtle Kinosternon leucostomum) aquatic respiration is via buccal or cutaneous routes whereas in pleurodires (e.g., Fitzroy River turtle Rheodytes leukops), it is achieved primarily via specialized cloacal bursae. This study records the voluntary diving performance of the western sawshelled turtle Myuchelys bellii in Bald Rock Creek from the temperate zone of the Murray–Darling Basin of Australia. Myuchelys bellii has a moderately specialized cloacal bursae morphology compared to other pleurodiran turtles and displays impressive dive durations spanning more than 15 days during the winter months. This is attributed to its ability to maintain aerobic dives via its cloacal bursae and low water temperatures in winter. Myuchelys bellii seasonal and diel diving performance, including its crepuscular habit, is comparable to R. leukops and Elseya albagula. This study also recorded the first aquatic hibernation at depth (>3 m) for any freshwater turtle; and only the second pleurodire to demonstrate aquatic hibernation as an overwintering strategy. Observed thermoregulation behavior in M. bellii is believed to provide multiple life history benefits.     

Energy and water flux during terrestrial estivation and overland movement in a freshwater turtle

The doubly labeled water (DLW) method for studying energy and water balance in field-active animals is not feasible for freshwater animals during aquatic activities, but several species of nominally aquatic reptiles leave wetlands for several critical and extended behaviors, where they face challenges to their energy and water balance. Using DLW, we studied energy and water relations during terrestrial estivation and movements in the eastern long-necked turtle (Chelodina longicollis), a species that inhabits temporary wetlands in southeastern Australia. Water efflux rates of 14.3-19.3 mL (kg d)(-1 ) during estivation were nearly offset by influx, indicating that turtles did not maintain water balance while terrestrial, though dehydration was slow. Estivation energy expenditure declined over time to 20.0-24.6 kJ (kg d)(-1) but did not indicate substantial physiological specializations. Energy reserves are predicted to limit survival in estivation to an estimated 49-261 d (depending on body fat), which is in close agreement with observed bouts of natural estivation in this population. The energy cost and water flux rates associated with overland movement behavior ranged from 46 to 99 kJ (kg d)(-1 ) and from 21.6 to 40.6 mL (kg d)(-1), respectively, for turtles moving 23-34 m d(-1). When a wetland dries, a turtle that forgoes movement to other wetlands can save sufficient energy to fuel up to 134 d in estivation. The increasing time in estivation with travel distance gained in this energy "trade-off" fits our previous observations that more turtles estivate when longer distances must be traveled to the nearest permanent lake, whereas emigration is nearly universal when only short distances must be traversed. The DLW method shows promise for addressing questions regarding the behavioral ecology and physiology of freshwater turtles in terrestrial situations, though validation studies are needed.     

Use of seasonal freshwater wetlands by fishes in a temperate river floodplain

This study examined the use of freshwater wetland restoration and enhancement projects ( i.e . non-estuarine wetlands subject to seasonal drying) by fish populations. To quantify fish use of freshwater emergent wetlands and assess the effect of wetland enhancement ( i.e . addition of water control structures), two enhanced and two unenhanced emergent wetlands were compared, as well as two oxbow habitats within the Chehalis River floodplain. Eighteen fish species were captured using fyke nets and emigrant traps from January to the beginning of June, with the most abundant being three-spined stickleback Gasterosteus aculeatus and Olympic mudminnow Novumbra hubbsi . Coho salmon Oncorhynchus kisutch was the dominant salmonid at all sites. Enhanced wetlands, with their extended hydroperiods, had significantly higher abundances of yearling coho salmon than unenhanced wetlands. Both enhanced and unenhanced emergent wetlands yielded higher abundances of non-game native fishes than oxbow habitats. Oxbow habitats, however, were dominated by coho salmon. Fish survival in the wetland habitats was dependent on emigration to the river before dissolved oxygen concentrations decreased and wetlands became isolated and stranding occurred. This study suggests that wetland enhancement projects with an outlet to the river channel appear to provide fishes with important temporary habitats if they have the opportunity to leave the wetland as dissolved oxygen levels deteriorate.     

Turtles in trouble. Conservation ecology and priorities for Australian freshwater turtles

The Australian freshwater turtle fauna is dominated by species in the family Chelidae. The extant fauna comprises a series of distinct lineages, each of considerable antiquity, relicts of a more extensive and perhaps diverse fauna that existed when wetter climes prevailed. Several phylogenetically distinctive species are restricted to single, often small, drainage basins, which presents challenges for their conservation. Specific threats include water resource development, which alters the magnitude, frequency, and timing of flows and converts lentic to lotic habitat via dams and weirs, fragmentation of habitat, sedimentation, nutrification, and a reduction in the frequency and extent of floodplain flooding. Drainage of wetlands and altered land use are of particular concern for some species that are now very restricted in range and critically endangered. The introduced European red fox is a devastatingly efficient predator of turtle nests and can have a major impact on recruitment. In the north, species such as the northern snake-necked turtle are heavily depredated by feral pigs. Other invasive animals and aquatic weeds dramatically alter freshwater habitats, with consequential impacts on freshwater turtles. Novel pathogens such as viruses have brought at least one species to the brink of extinction. Species that routinely migrate across land are impacted by structural simplification of habitat, reduction in availability of terrestrial refugia, fencing (including conservation fencing), and in some areas, by high levels of road mortality. We report on the listing process and challenges for listing freshwater turtles under the Australian Environment Protection and Biodiversity Conservation Act, summarize the state of knowledge relevant to listing decisions, identify the key threatening processes impacting turtles, and identify key knowledge gaps that impede the setting of priorities. We also focus on how to best incorporate First Nations Knowledge into decisions on listing and discuss opportunities to engage Indigenous communities in on-ground work to achieve conservation outcomes.     

青海湖3种类型高寒湿地甲烷氧化菌群落特征

【背景】甲烷氧化菌在维持湿地生态系统碳平衡方面发挥着重要作用,青海湖高寒湿地具有十分重要的生态地位,但目前有关该地区甲烷氧化菌的研究相对较少。【目的】探究不同类型高寒湿地土壤甲烷氧化菌的群落特征与驱动因素。【方法】以青海湖流域内的小泊湖沼泽湿地、鸟岛湖滨湿地、瓦颜山河源湿地为研究对象,通过高通量测序技术对土壤甲烷氧化菌进行检测。【结果】3种不同类型高寒湿地土壤甲烷氧化菌的优势菌门均为变形菌门(Proteobacteria)。鸟岛湖滨湿地与瓦颜山河源湿地的甲烷氧化菌α多样性存在显著差异(P<0.05),而小泊湖沼泽湿地与二者的甲烷氧化菌α多样性的差异不显著(P>0.05)。LEfSe分析表明,不同类型高寒湿地共存在40个差异菌群,尤以瓦颜山河源湿地差异菌群数量最多,从门到属水平均存在显著差异。冗余分析(redundancy analysis,RDA)表明,甲烷氧化菌菌群变化的主要驱动因子为土壤温度、土壤水分、电导率。【结论】整体而言,青海湖3种类型高寒湿地土壤理化性质及甲烷氧化菌群落多样性均存在差异,且部分菌群的相对丰度具有显著性差异(P<0.05)。     

Seed Banks in Arid Wetlands with Contrasting Flooding,Salinity and Turbidity Regimes

Aquatic plant communities in arid zone wetlands underpin diverse fauna populations and ecosystem functions yet are relatively poorly known. Erratic flooding, drying, salinity and turbidity regimes contribute to habitat complexity, creating high spatial and temporal variability that supports high biodiversity. We compared seed bank density, species richness and community composition of aquatic plants (submergent, floating-leaved and emergent) among nine Australian arid zone wetlands. Germinable seed banks from wetlands within the Paroo and Bulloo River catchments were examined at nested scales (site, wetland, wetland type) using natural flooding and salinity regimes as factors with nondormant seed density and species richness as response variables. Salinity explained most of the variance in seed density (95%) and species richness (68%), with flooding accounting for 5% of variance in seed density and 32% in species richness. Salinity-flooding interactions were significant but explained only a trivial portion of the variance (<1%). Mean seed densities in wetlands ranged from 40 to 18,760 m⁻² and were highest in wetlands with intermediate levels of salinity and flooding. Variability of densities was high (CVs 0.61–2.66), particularly in saline temporary and fresh permanent wetlands. Below salinities of c. 30 g l⁻¹ TDS, seed density was negatively correlated to turbidity and connectivity. Total species richness of wetlands (6–27) was negatively correlated to salinity, pH and riverine connectivity. A total of 40 species germinated, comprising submergent (15 species), floating-leaved or amphibious (17 species), emergent (6 species) and terrestrial (6 species) groups. Charophytes were particularly important with 10 species (five Chara spp., four Nitella spp. and Lamprothamnium macropogon), accounting for 68% of total abundance. Saline temporary wetlands were dominated by Ruppia tuberosa, Lamprothamnium macropogon and Lepilaena preissii. Variable flooding and drying regimes profoundly altered water quality including salinity and turbidity, producing distinctive aquatic plant communities as reflected by their seed banks. This reinforces the importance of hydrology in shaping aquatic biological communities in arid systems.     

International migrations of South American sea turtles (Cheloniidae and Dermochelidae)

Three species of sea turtles (the leatherback, Dermochelys coriacea; the green turtle, Chelonia mydas; and the olive ridley, Lepidochelys olivacea) nest abundantly in the Guianas, especially on the beaches adjacent to the mouth of the Marowijne River. Tagging demonstrated that green turtles nesting in Surinam are recruited from feeding grounds in or near the State of Ceará, Brazil, while olive ridleys, after nesting in Surinam, spread out over 3800 km of the coast of northern South America. A single tagged leatherback was recovered in Ghana.     

The relative importance of wetland size and hydroperiod for amphibians in southern New Hampshire,USA

In the United States, the regulatory approach to wetland protection has a traditional focus on size as a primary criterion, with large wetlands gaining significantly more protection. Small, isolated wetlands have received less protection; however, these wetlands play a significant role in the maintenance of biodiversity of many taxonomic groups, including amphibians. An important question for directing conservation and management efforts for amphibians is whether size is a useful criterion for regulatory decisions. Because hydroperiod has an important influence on amphibian composition in wetlands, I conducted a study to examine the relative influence of wetland size and hydroperiod on amphibian occurrence. I sampled 103 wetlands in southern New Hampshire in 1998 and 1999 using dipnet sampling to document the presence of larval amphibians. Wetlands were placed into one of three hydroperiod categories; short (<4 months), intermediate (4–11 months), or long (permanent) based on field observations of drying pattern. Wetland size was determined from digitized national wetland inventory (NWI) maps (most wetlands) or measured in the field. I examined patterns of amphibian species richness and individual species occurrence using generalized linear models. Wetland size ranged from 0.01 to 3.27 ha. Overall, species richness was significantly influenced by hydroperiod (χ² = 18.6, p <0.001), but not size (χ² = 1.4, p = 0.24). Examination within hydroperiod categories revealed several significant relationships with wetland size. Species richness was related to wetland size in wetlands with short and intermediate hydroperiods, but not wetlands with long hydroperiods. Wetland size does not appear to be a useful sole criterion for determining wetland functional value for amphibians; assessments of functions of seasonally inundated wetlands for amphibians would benefit from examination of hydroperiod.     

Simulating the Effects of Sea Level Rise on the Resilience and Migration of Tidal Wetlands along the Hudson River

Sea Level Rise (SLR) caused by climate change is impacting coastal wetlands around the globe. Due to their distinctive biophysical characteristics and unique plant communities, freshwater tidal wetlands are expected to exhibit a different response to SLR as compared with the better studied salt marshes. In this study we employed the Sea Level Affecting Marshes Model (SLAMM), which simulates regional- or local-scale changes in tidal wetland habitats in response to SLR, and adapted it for application in a freshwater-dominated tidal river system, the Hudson River Estuary. Using regionally-specific estimated ranges of SLR and accretion rates, we produced simulations for a spectrum of possible future wetland distributions and quantified the projected wetland resilience, migration or loss in the HRE through the end of the 21^st century. Projections of total wetland extent and migration were more strongly determined by the rate of SLR than the rate of accretion. Surprisingly, an increase in net tidal wetland area was projected under all scenarios, with newly-formed tidal wetlands expected to comprise at least 33% of the HRE’s wetland area by year 2100. Model simulations with high rates of SLR and/or low rates of accretion resulted in broad shifts in wetland composition with widespread conversion of high marsh habitat to low marsh, tidal flat or permanent inundation. Wetland expansion and resilience were not equally distributed through the estuary, with just three of 48 primary wetland areas encompassing >50% of projected new wetland by the year 2100. Our results open an avenue for improving predictive models of the response of freshwater tidal wetlands to sea level rise, and broadly inform the planning of conservation measures of this critical resource in the Hudson River Estuary.