Search

Environmental monitoring guides conservation and is particularly important for aquatic habitats which are heavily impacted by human activities. Underwater cameras and uncrewed devices monitor aquatic wildlife, but manual processing of footage is a significant bottleneck to rapid data processing and dissemination of results. Deep learning has emerged as a solution, but its ability to accurately detect animals across habitat types and locations is largely untested for coastal environments. Here, we produce five deep learning models using an object detection framework to detect an ecologically important fish, luderick (Girella tricuspidata). We trained two models on footage from single habitats (seagrass or reef) and three on footage from both habitats. All models were subjected to tests from both habitat types. Models performed well on test data from the same habitat type (object detection measure: mAP50: 91.7 and 86.9% performance for seagrass and reef, respectively) but poorly on test sets from a different habitat type (73.3 and 58.4%, respectively). The model trained on a combination of both habitats produced the highest object detection results for both tests (an average of 92.4 and 87.8%, respectively). The ability of the combination trained models to correctly estimate the ecological abundance metric, MaxN, showed similar patterns. The findings demonstrate that deep learning models extract ecologically useful information from video footage accurately and consistently and can perform across habitat types when trained on footage from the variety of habitat types. [ABSTRACT FROM AUTHOR]

Effective methods for graphite felt (GF) treatment based on Fenton's reagent treatment and thermal modification have been used to improve microbial fuel cell (MFC) performance. The effects of the HO content in Fenton's reagent on the performances of MFCs with two different GFs (GFD and ACN-211) have been investigated. For GFD, a maximum performance of 190 mW/m was achieved with HO volume of 100 ml, while for ACN-211, the maximum performance of 450 mW/m is reached with HO volume of 150 ml. MFCs with both treated and untreated ACN-211 consistently showed higher power densities and greater durabilities than those with treated and untreated GFD. The degree of fouling on the surface of ACN-211 was much less than that on the surface of GFD. The higher surface area and better anti-fouling performance of ACN-211 are responsible for its relatively high power density during long-term operation. Thermal modification of ACN-211 was performed at different temperatures and for different durations, and the effects of treatment conditions on the performances of MFCs were studied. Results showed that an MFC fabricated with ACN-211 treated under 400 °C for 2 h exhibited the highest power density, with a maximum value of 470 mW/m, which is higher than that of an MFC fabricated with ACN-211 treated by Fenton's reagent. A Coulombic efficiency of 35% and an energy efficiency of 10% were achieved for an MFC fabricated with ACN-211. [ABSTRACT FROM AUTHOR]

Understanding how salinity affects marine parasites is vital to understanding their ecology and treatment, particularly for host-parasite systems that traverse marine and freshwater realms such as the globally important Atlantic salmon (Salmo salar), salmon louse (Lepeophtheirus salmonis) system. Growing concerns for wild fish populations, and decreased efficiencies and burgeoning costs of lice treatments for farmed fish has necessitated more environmentally and socially acceptable delousing procedures, such as hyposaline treatments. The effect of brackish water on L. salmonis following primary attachment is largely unknown, with experimental evidence derived mostly from unattached or newly attached copepodids, or adult stages. We aimed to understand how attached lice respond to hyposaline environments to assess effectiveness as a parasite management strategy and to help better define delousing areas used by wild fish. Louse development at 4, 12, 19 and 26 ppt, and survival at 4 ppt, decreased as exposure times increased, but survival was otherwise unaffected. Subjecting salmon to fluctuating, repeat exposures did not influence efficacy. We confirm that free-swimming stages are susceptible, and show that attached copepodids were more tolerant than previously predicted based on experiments on alternate development stages. These results improve our understanding of the utility of hyposaline treatments in aquaculture and self-treating in wild fish, and could apply to other fish-lice parasite systems. Further, these data are important for models predicting host-parasite interactions and can contribute to predictive models on the transmission dynamics of sea lice from farm to wild fish. [ABSTRACT FROM AUTHOR]

This paper is concerned with a space-time discretization of a rate-independent evolution governed by a non-smooth dissipation and a non-convex energy functional. For the time discretization, we apply the local minimization scheme introduced in Efendiev and Mielke (J Convex Anal 13(1):151-167, 2006), which is known to resolve time discontinuities, which may show up due to the non-convex energy. The spatial discretization is performed by classical linear finite elements. We show that accumulation points of the sequence of discrete solutions for mesh size tending to zero exist and are so-called parametrized solutions of the continuous problem. The discrete problems are solved by means of a mass lumping scheme for the non-smooth dissipation functional in combination with a semi-smooth Newton method. A numerical test indicates the efficiency of this approach. In addition, we compared the local minimization scheme with a time stepping scheme for global energetic solutions, which shows that both schemes yield different solutions with differing time discontinuities. [ABSTRACT FROM AUTHOR]