Modeling Habitat Suitability and Management Options for Maintaining Round Whitefish (Prosopium cylindraceum) in Adirondack Ponds

Habitat loss, acid precipitation, and nonnative species have drastically reduced the number of Adirondack waterbodies occupied by round whitefish (Prosopium cylindraceum). The goal of this study was to 1) increase the probability of reintroduction success by modeling the suitability of ponds for reintroduction and 2) better understand the effects of different rates of pond reclamation. We created a species distribution model that identified 70 waterbodies that were physically similar to occupied ponds. The most influential variables for describing round whitefish habitat included trophic, temperature, and alkalinity classes; waterbody maximum depth; maximum air temperature; and surrounding soil texture and impervious surface. Next, we simulated population dynamics under a variety of treatment scenarios and compared the probability of complete extirpation using a modified Markov model. Under almost all management strategies, and under pressure from nonnative competitors like that observed in the past 30 years, the number of occupied ponds will decline over the next 100 years. However, restoring one pond every 3 years would result in a 99% chance of round whitefish persistence after 100 years.

P556 Long-term probability of retreatment with anti-TNF therapy after discontinuation based on mucosal healing in inflammatory bowel disease

Background To evaluate the need for retreatment with anti-TNF due to relapse after discontinuation based on mucosal healing in inflammatory bowel disease (IBD), as well as the influencing factors and the response to reintroduction. Methods Descriptive retrospective study of IBD patients in whom anti-TNF treatment was discontinued after mucosal healing had been proved, between June 2009 and May 2016. Demographic and phenotypic characteristics, biologic and immunomodulator (IM) therapy history, laboratory markers and histopathologic evaluation were noted. We evaluated the relapse rate after discontinuation of anti-TNF, as well as the need for reintroduction and its success rate. Results We included 100 patients, 69 of them affected by Crohn’s disease (CD), 29 with ulcerative colitis (UC) and 2 unclassified colitis. From those with CD, inflammatory behaviour (62%) and ileocolonic localisation (53%) were the most frequent conditions. Seventy-four per cent of UC patients had pancolonic involvement. Biological therapy had been indicated because of corticodependence in 66% (vs. 32% corticorefractoriness). The anti-TNF drug was infiliximab in 60 patients, adalimumab in 38, 1 certolizumab and one had been treated with golimumab. Endoscopic biopsies showed quiescent disease in 63 of 83 patients. Eighty-three per cent of patients were treated with IM after removal of anti-TNF. After a mean follow-up of 57 months, 63 patients relapsed, 52 of them needing anti-TNF reintroduction. Reintroduction rates at 12, 36 and 60 months were 19.5%, 43.5% and 52% respectively with a response after the re-treatment of 76,6%. Univariant analysis showed a higher risk in CD (61 vs. 31%, p = 0.008). Within the CD patients, the risk of reintroduction was lower in A3 (30 vs. 66%, p = 0.03) and B2 (31 vs. 69%, p = 0.006) patterns, and higher if the indication had been corticodependence (68% vs. 37%, p = 0.02). Multivariant analysis confirms the protective effect of B2 behaviour and worse outcomes for corticodependence antecedent. Considering UC, the retreatment probability was superior for those patients without IM therapy after anti-TNF discontinuation (57 vs. 22%), although this association did not reach statistical significance (p = 0.08). Conclusion The risk of needing reintroduction of anti-TNF therapy after mucosal healing in IBD is around 50% in 5 years, being superior in CD patients. Reintroduction success rate is 76%. In CD, this risk is higher when the reason for starting anti-TNF was corticodependence, and much lower when stricturing/fibrotic pattern predominates. For UC patients, anti-TNF drugs should not be stopped if IM therapy cannot be held.

Using environmental DNA to monitor the reintroduction success of the Rhine sculpin (Cottus rhenanus) in a restored stream

Freshwaters face some of the highest rates of species loss, caused by strong human impact. To decrease this strong impact, ecological restorations are increasingly applied to restore and maintain the natural ecological status of freshwaters. Their ecological status can be determined by assessing the presence of indicator species (e.g. certain fish species), which is called biomonitoring. However, traditional biomonitoring of fish, such as electrofishing, is often challenging and invasive. To augment traditional biomonitoring of fish, the analysis of environmental DNA (eDNA) has recently been proposed as an alternative, sensitive approach. The present study employed this modern approach to monitor the Rhine sculpin (Cottus rhenanus), a fish species that has been reintroduced into a recently restored stream within the Emscher catchment in Germany, in order to validate the success of the applied restorations and to monitor the species’ dispersal. We monitored the dispersal of the Rhine sculpin using replicated 12S end-point PCR eDNA surveillance at a fine spatial and temporal scale. In that way, we investigated if eDNA analysis can be applied for freshwater assessments. We also performed traditional electrofishing in one instance to validate our eDNA-based approach. We could track the dispersal of the Rhine sculpin and showed a higher dispersal potential of the species than we assumed. We validated the species’ dispersal across a potential dispersal barrier via eDNA detection and showed a steep increase of positive detections once the reintroduced population had established. In contrast to that, false negative eDNA results occurred at early reintroduction stages. Our results show that eDNA detection can be used to confirm and monitor reintroductions and to contribute to the assessment and modelling of ecological status of streams.

Using environmental DNA to monitor the reintroduction success of the Rhine sculpin (Cottus rhenanus) in a restored stream

Freshwaters face some of the highest rates of species loss, caused by strong human impact. To decrease this strong impact, ecological restorations are increasingly applied to restore and maintain the natural ecological status of freshwaters. Their ecological status can be determined by assessing the presence of indicator species (e.g. certain fish species), which is called biomonitoring. However, traditional biomonitoring of fish, such as electrofishing, is often challenging and invasive. To augment traditional biomonitoring of fish, the analysis of environmental DNA (eDNA) has recently been proposed as an alternative, sensitive approach. The present study employed this modern approach to monitor the Rhine sculpin (Cottus rhenanus), a fish species that has been reintroduced into a recently restored stream within the Emscher catchment in Germany, in order to validate the success of the applied restorations and to monitor the species’ dispersal. We monitored the dispersal of the Rhine sculpin using replicated 12S end-point PCR eDNA surveillance at a fine spatial and temporal scale. In that way, we investigated if eDNA analysis can be applied for freshwater assessments. We also performed traditional electrofishing in one instance to validate our eDNA-based approach. We could track the dispersal of the Rhine sculpin and showed a higher dispersal potential of the species than we assumed. We validated the species’ dispersal across a potential dispersal barrier via eDNA detection and showed a steep increase of positive detections once the reintroduced population had established. In contrast to that, false negative eDNA results occurred at early reintroduction stages. Our results show that eDNA detection can be used to confirm and monitor reintroductions and to contribute to the assessment and modelling of ecological status of streams.

Reservoir frogs: seasonality of Batrachochytrium dendrobatidis infection in robber frogs in Dominica and Montserrat

Emerging infectious diseases are an increasingly important threat to wildlife conservation, with amphibian chytridiomycosis, caused by Batrachochytrium dendrobatidis, the disease most commonly associated with species declines and extinctions. However, some amphibians can be infected with B. dendrobatidis in the absence of disease and can act as reservoirs of the pathogen. We surveyed robber frogs (Eleutherodactylus spp.), potential B. dendrobatidis reservoir species, at three sites on Montserrat, 2011–2013, and on Dominica in 2014, to identify seasonal patterns in B. dendrobatidis infection prevalence and load (B. dendrobatidis genomic equivalents). On Montserrat there was significant seasonality in B. dendrobatidis prevalence and B. dendrobatidis load, both of which were correlated with temperature but not rainfall. B. dendrobatidis prevalence reached 35% in the cooler, drier months but was repeatedly undetectable during the warmer, wetter months. Also, B. dendrobatidis prevalence significantly decreased from 53.2% when the pathogen emerged on Montserrat in 2009 to a maximum 34.8% by 2011, after which it remained stable. On Dominica, where B. dendrobatidis emerged seven years prior to Montserrat, the same seasonal pattern was recorded but at lower prevalence, possibly indicating long-term decline. Understanding the dynamics of disease threats such as chytridiomycosis is key to planning conservation measures. For example, reintroductions of chytridiomycosis-threatened species could be timed to coincide with periods of low B. dendrobatidis infection risk, increasing potential for reintroduction success.