New England Aquarium

Aim Climate change is causing distributional shifts in many species globally. identifying and anticipating these shifts is critical to understanding ecosystem impacts and implementing successful management strategies. species distribution models (SDMs) are useful tools often employed to describe current and changing habitat use, particularly for marine predators. However, most SDMs assume the statistical relationships between species and their environment are temporally static, which may not be true. We examined how incorporating temporal variability improved SDM performance and estimated range shifts for six Odontocete species. We used a high performing model to quantify changes in Odontocete distribution over a 24-year period.Location Waters of the United States, east coast, from Florida to Nova Scotia.Methods We utilised nearly 1.4 million kilometres of line transect survey data collected from 1997 to 2020 along the East Coast of the United States to evaluate changes in the distribution of six Odontocete species. We assessed six model specifications of generalise additive models that varied in the extent of temporal and spatial variability incorporated.Results We found that the best performing model specifications included temporally dynamic species-environment relationships and temporally dynamic spatial terms. These model specifications identified significant poleward range shifts in all species for which we had sufficient data across their range. In contrast, model specifications which only included static terms performed poorly and identified limited or no spatial shifts.Main Conclusions These results advance our predictive capabilities from static species-environment relationships for marine predators and demonstrate the importance of carefully considering assumptions and model specifications when modelling changes to distributions. The odontocete range shifts we identified are likely to have substantial ecosystem impacts, and the framework we present offers a diagnostic approach for modelling and identifying range shifts in other wide-ranging species.

IntroductionEstimating the genetic diversity of cetaceans at sea, particularly abundant social delphinids, can be difficult with traditional biopsy sampling of individuals. Environmental DNA (eDNA) metabarcoding has been shown to be a powerful tool for the identification of species assemblages and estimation of genetic diversity, especially in aquatic environments.MethodsWe collected 126 samples of seawater from within the immediate vicinity of schools of dolphins during 15 encounters with the four most common delphinid taxa in the waters around Santa Catalina Island, California, USA: long-beaked common dolphins (Delphinus delphis bairdii, n = 8), short-beaked common dolphins (D. d. delphis, n = 3), common bottlenose dolphins (Tursiops truncatus, n = 2), and Risso's dolphins (Grampus griseus, n = 2). Next-generation sequencing was used to assign Amplicon Sequence Variants (ASVs) of mitochondrial DNA to species using GenBank and a region-specific reference database.ResultsA total of 240 ASVs were resolved for the four species. ASV richness and the effective number of ASVs, or true diversity, measured as Hill numbers of order 1, were consistent with known characteristics of the four species. Despite collecting up to 12 samples from a single group, a rarefaction analysis indicated that the population diversity was not fully represented for the more abundant species (genus Delphinus), but were closely approximated for G. griseus.DiscussionThis study demonstrates the application of eDNA for estimating population genetic diversity of abundant species and makes recommendations for improving future studies to better capture this diversity in wild delphinid populations. This provides a more solid foundation for studies using eDNA to monitor these species, which often include those in close proximity to anthropogenic threats.

Sea turtle populations are imperiled globally, primarily due to anthropogenic threats. However, non-anthropogenic factors, such as infectious diseases, can affect their population stability. Viruses are common causes of gastrointestinal disease in many species, and gastrointestinal signs are regularly observed among sea turtles, but little is known about enteric viruses in sea turtles. Establishing basic knowledge of viral diversity and evolutionary relationships is a necessary step towards understanding potential health impacts. This study investigated the viral genome contents of seventy-seven gastrointestinal specimens from six species of sea turtles with varying health conditions from the Atlantic and Pacific coasts of the United States. Forty-eight, non-plant and non-bacteria infecting viruses were detected (≥5 viral-like reads per sample) through random RNA sequencing. Detected viral sequences were then confirmed and characterized by semi-targeted, strand-switching sequencing, which provided deeper sequencing metrics allowing for phylogenetic characterization (>10× depth) for nineteen viruses across eight viral families, including seven putative novel viral species, one putative novel genus, and eleven likely novel viral sequences from taxa that lack established species demarcation criteria. Sixteen RNA viruses were characterized: four double-stranded RNA viruses (Partitiviridae, Totiviridae, and Picobirnaviridae), eleven positive-sense single-stranded RNA viruses (Caliciviridae, Dicistroviridae, unclassified Hepelivirales, and unclassified Picornavirales), and one negative-sense bisegmented RNA virus (Chuviridae). Three DNA viruses were also identified (Parvoviridae, Circoviridae, and unclassified Cressdnaviricota). Viruses identified in this study were often genetically related to viruses previously known to infect aquatic invertebrates and fish. This study provides baseline knowledge of viral communities in sea turtles and will serve as a foundation for future hypothesis-driven research to understand their relevance to sea turtle health.

Eastern box turtles (Terrapene carolina carolina) are declining range-wide due to anthropogenic factors, including the illegal wildlife trade. Infectious diseases that cause high morbidity and mortality, such as frog virus 3 (family Iridoviridae, genus Ranavirus, species Rana1), may also threaten this species in managed-care and free-ranging settings. High rates of infectious disease transmission are documented within the illegal wildlife trade; however, the impact of diseases on health, survival, and ultimate disposition of confiscated turtles is not thoroughly described. In July 2021, 96 eastern box turtles were seized by the US Fish and Wildlife Service while illegally en route to Asia and were relocated to three zoos via the Association of Zoos and Aquariums' Saving Animals from Extinction American Turtles program. From July-August, 35 individuals were selected for pathogen surveillance, of which (94%) were qPCR positive for frog virus 3 (FV3; recently renamed Ranavirus rana1), 100% were positive for Mycoplasmopsis sp. (BTMyco), 80% were positive for Terrapene herpesvirus 1 (TerHV1), and 60% were positive for Terrapene adenovirus (TerAdv). At least two pathogens were co-detected in each turtle. Forty of the original 96 turtles died (31 of the 35 tested turtles), and in September 2021, the surviving 56 (4 from the subset of 35) turtles were transferred to the University of Illinois. These remaining turtles tested qPCR positive for FV3 (32%), BTMyco (64%), TerAdv (64%), TerHV1 (66%), Terrapene herpesvirus 2 (18%), and human-pathogenic Leptospira spp. (2%). Multiple pathogens were co-detected in 41 turtles (73%). All 56 turtles brumated over winter in 2021 and were found dead in May 2022, with autolysis limiting diagnostic necropsy. The complete mortality of 96 confiscated eastern box turtles demonstrates that poor health and disease transmission negatively impact the welfare and survival of illegally traded animals.