Delta Smelt (Hypomesus transpacificus) Exhibit Wide Variation in Spawning Behavior: An Investigation of Substrate Type, Diel Timing, and Participants

Studies of cultured populations can be invaluable to the conservation of imperiled species for which little is known and whose very low abundance in the wild can preclude studies with robust sample sizes. For example, in endangered delta smelt (Hypomesus transpacificus), conservation measures developed to mitigate population decline are hindered by a lack of knowledge regarding spawning behavior. However, the availability of a cultured population allows important questions about spawning to be addressed experimentally. We examined the effect of substrate type on spawning behavior and egg fertilization success in cultured H. transpacificus under laboratory conditions. We also examined the diel frequency of spawning and the sex and number of spawning participants. We found that the frequency of spawns and resulting egg fertilization success did not differ between sand, gravel, and control (acrylic) substrates. We also demonstrated that spawning was predominantly nocturnal, though rare diurnal spawns were observed. Of the five mature males and five ripe females available within a given trial, spawns included up to seven participants, but most frequently occurred between a single female and one or two males. Our results highlight the wide behavioral variation exhibited by H. transpacificus during spawning, particularly in terms of substrate use, diel timing, and participants. These findings provide the most detailed and experimentally robust data regarding H. transpacificus spawning behavior to date and thereby provide ongoing conservation efforts with much-needed information.

First person – Jillian Josimovich

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping early-career researchers promote themselves alongside their papers. Jillian Josimovich is first author on ‘ Clutch may predict growth of hatchling Burmese pythons better than food availability or sex’, published in BiO. Jillian is a biologist in the lab of Dr Andrea Currylow at Geological Survey, Fort Collins Science Center, South Florida Field Station in Everglades National Park, USA, investigating applied research that can inform management efforts for imperiled species and ecosystems, with a particular focus on herpetological ecology and conservation.

Status of the recovery mandate under section 7(a)(1) of the U.S. Endangered Species Act

The U.S. Endangered Species Act (ESA) is widely considered to be one of the strongest laws for protecting imperiled wildlife, with nearly all species protected under the law still existing today. Among the ESA’s strongest provisions, at least as written, is the requirement under section 7(a)(1) that federal agencies use their authorities to help recover imperiled species. New initiatives like 30x30, the campaign to conserve at least thirty percent of U.S. lands and waters by 2030, offer opportunities to reinvigorate and expand 7(a)(1) programs to play a significant role in biodiversity conservation. To gauge the current status of 7(a)(1) plans and assess their effectiveness, we collected all section 7(a)(1) materials available to the public through internet searches and direct requests to agencies. We evaluated the scope of existing 7(a)(1) programs and found that despite the clear potential benefits of a strong 7(a)(1) program, the section has been significantly underused by federal agencies. Further, we show that existing plans are highly inconsistent in content and style, and we trace that inconsistency to the lack of policy guidance for their creation and implementation. Based on these findings, we recommend four strategies for improving 7(a)(1) implementation: establishment of formal guidance from federal wildlife agencies, tailored guidance from other federal agencies to help them meet their 7(a)(1) obligation, and dedicated funding.

Targeting current species ranges and carbon stocks fails to conserve biodiversity in a changing climate: opportunities to support climate adaptation under 30x30

Protecting areas for climate adaptation will be essential to ensuring greater opportunity for species conservation well into the future. However, many proposals for protected areas expansion focus on our understanding of current spatial patterns, which may be ineffective surrogates for future needs. A science-driven call to address the biodiversity and climate crises by conserving at least 30% of lands and waters by 2030, 30x30, presents new opportunities to inform the siting of new protections globally and in the U.S. Here we identify climate refugia and corridors based on a weighted combination of currently available models; compare them to current biodiversity hotspots and carbon-rich areas to understand how 30x30 protections siting may be biased by data omission; and compare identified refugia and corridors to the Protected Areas Database to assess current levels of protection. Available data indicate that 20.5% and 27.5% of identified climate adaptation areas (refugia and/or corridor) coincides with current imperiled species hotspots and carbon-rich areas, respectively. With only 12.5% of climate refugia and corridors protected, a continued focus on current spatial patterns in species and carbon richness will not inherently conserve places critical for climate adaptation. However, there is ample opportunity for establishing future-minded protections: 52% of the contiguous U.S. falls into the top quartile of values for at least one class of climate refugia. Nearly 27% is already part of the protected areas network, but managed for multiple uses that may limit their ability to contribute to the goals of 30x30. Additionally, nearly two-thirds of nationally identified refugia coincide with ecoregion-specific refugia suggesting representation of nearly all ecoregions in national efforts focused on conserving climate refugia. Based on these results, we recommend that land planners and managers make more explicit policy priorities and strategic decisions for future-minded protections and climate adaptation.

Use of Drift Studies to Understand Seasonal Variability in Sea Turtle Stranding Patterns in Mississippi

Stranded sea turtles provide valuable information about causes of mortality that threatens these imperiled species. Many potential factors determine whether drifting sea turtles are deposited on shore, discovered by people, and reported to stranding networks resulting in successful documentation. We deployed 182 sea turtle cadavers and 115 wooden effigy drifters with affixed GPS-satellite tags to study stranding probability in the northern Gulf of Mexico (nGOM) in an effort to better understand seasonal stranding variations in this region. Public reports of beached carcasses were recorded to determine reporting rates. Season and distance from shore greatly influenced beaching results. During winter months when strandings are infrequent and sea turtle abundance is likely low in cold nearshore waters, carcasses had an 80–90% probability of beaching. Beaching probability was reduced to 37–50% during the spring, which is the period of greatest strandings in this region. During summer months when relatively few strandings are documented, the probability of a carcass beaching dropped to only 4–8%. Low summer stranding rates were coincident with higher rates of decomposition (7%) attributed to warmer water temperatures, more frequent scavenging (69% of carcasses), and shifting wind and current patterns which drive carcasses offshore or to remote locations. As waters cooled in the fall, probability of carcasses beaching increased to 40–48%, coincident with a small pulse in strandings that often occurs during this period. Only 28% of carcasses and effigies came ashore on mainland beaches and were easily available for discovery by the public, 49% were on barrier islands that are publicly accessible and 23% beached in dense salt marshes where discovery would be unlikely. The 47% of objects that did not beach included those lost at sea and carcasses that were likely scavenged or decomposed. Only 22% of beached carcasses were reported due to infrequent (11%) reporting on barrier islands. Notably, only 50% of carcasses deposited on mainland beaches were reported, which was lower than anticipated. We recommend additional efforts to increase reporting rates of carcasses by the public and use of dedicated surveys to detect stranded sea turtles, especially on barrier islands in this region.

Eye lenses reveal ontogenetic trophic and habitat shifts in an imperiled fish, Clear Lake Hitch Lavinia exilicauda chi

Stable isotopes recorded in fish eye lenses are an emerging tool to track dietary shifts coincident with use of diverse habitats over the lifetime of individuals. Eye lenses are metabolically inert, sequentially deposited, archival tissues that can open avenues to chronicle contaminant exposures, diet histories, trophic dynamics and migratory histories of individual fishes. In this study, we demonstrated that trophic histories reconstructed using eye lenses can resolve key uncertainties regarding diet and trophic habitat shifts. Clear Lake Hitch Lavinia exilicauda chi, a threatened cyprinid, inhabits a single lake (Clear Lake, Lake County, California) and utilizes tributary streams for reproduction. Bayesian mixing models applied to δ13C and δ15N recorded in eye lenses uncovered ontogenetic diet shifts that corresponded with shifts in occupation of habitats providing spawning (tributary streams), rearing (littoral lake), and growth (pelagic lake) functions. The reconstruction of size-structured trophic and habitat information can provide vital information needed to manage and conserve imperiled species such as the Clear Lake Hitch.

Maximizing regional biodiversity requires a mosaic of protection levels

Protected areas are the flagship management tools to secure biodiversity from anthropogenic impacts. However, the extent to which adjacent areas with distinct protection levels host different species numbers and compositions remains uncertain. Here, using reef fishes, European alpine plants, and North American birds, we show that the composition of species in adjacent Strictly Protected, Restricted, and Non-Protected areas is highly dissimilar, whereas the number of species is similar, after controlling for environmental conditions, sample size, and rarity. We find that between 12% and 15% of species are only recorded in Non-Protected areas, suggesting that a non-negligible part of regional biodiversity occurs where human activities are less regulated. For imperiled species, the proportion only recorded in Strictly Protected areas reaches 58% for fishes, 11% for birds, and 7% for plants, highlighting the fundamental and unique role of protected areas and their environmental conditions in biodiversity conservation.

Microsatellite Loci for the Threatened Pearl Darter and Cross Amplification in Channel and Coal Darters

The Pearl Darter Percina aurora is an imperiled species of fish currently only found in the Pascagoula River drainage in southern Mississippi. We tested 60 microsatellite loci identified by Illumina pair-ended sequencing. Forty of these loci were polymorphic in Pearl Darters with a mean number of alleles per locus of 11.5 and mean observed and expected heterozygosity values of 0.818 and 0.805, respectively. Eleven to 17 of these loci were also polymorphic in the closely related Channel Darter P. copelandi and Coal Darter P. brevicauda. These loci should prove useful in genetic studies associated with informing future management decisions for Pearl Darters and conservation efforts in other species of darter.

Rangeland Land-Sharing, Livestock Grazing’s Role in the Conservation of Imperiled Species

Land sharing, conserving biodiversity on productive lands, is globally promoted. Much of the land highest in California’s biodiversity is used for livestock production, providing an opportunity to understand land sharing and species conservation. A review of United States Fish and Wildlife Service listing documents for 282 threatened and endangered species in California reveals a complex and varied relationship between grazing and conservation. According to these documents, 51% or 143 of the federally listed animal and plant species are found in habitats with grazing. While livestock grazing is a stated threat to 73% (104) of the species sharing habitat with livestock, 59% (85) of the species are said to be positively influenced, with considerable overlap between species both threatened and benefitting from grazing. Grazing is credited with benefiting flowering plants, mammals, insects, reptiles, amphibians, fish, crustaceans, and bird species by managing the state’s novel vegetation and providing and maintaining habitat structure and ecosystem functions. Benefits are noted for species across all of California’s terrestrial habitats, except alpine, and for some aquatic habitats, including riparian, wetlands, and temporary pools. Managed grazing can combat anthropomorphic threats, such as invasive species and nitrogen deposition, supporting conservation-reliant species as part of land sharing.