Contributors: Ogburn, Matthew Bryan
... Crustacean fisheries often preferentially or exclusively harvest males, resulting in selection that alters sex ratios in fished populations. Sex-biased fisheries may occur when males are larger and fisheries are size-selective, or when regulations limit or prohibit harvest of females to protect sufficient spawning stock to maintain the population. This review explores the evidence for fishery-induced alterations in sex ratios in crustacean fisheries and the resulting effects on reproductive output at the level of the individual and population. Crustacean fisheries exhibit substantial spatial and temporal variation in exploitation, which could lead to hotspots of altered sex ratios. Experimental manipulations simulating the effects of selective harvest indicate that altered sex ratios can lead to sperm limitation and reduction in the reproductive output of individual females. The effects of altered sex ratios on reproduction at the population scale remain poorly understood. Future directions for improving our understanding of the effects of altered sex ratios on reproductive output include focused studies on sperm limitation at high fishery exploitation rates, model simulations of population scale reproductive output that account for individual variation in sperm quantity, and detailed studies of sperm storage and use during fertilization.
Effects of elevated CO2 on growth, calcification and spectral dependence of photoinhibition in the coccolithophore Emiliania huxleyi (Prymnesiophyceae)
Contributors: Lorenzo, M. R., Neale, Patrick J., Sobrino, Cristina, León, Pablo, Vázquez, Víctor, Bresnan, Eileen, Segovia, María
... We studied the effects of elevated CO2 concentrations on cell growth, calcification and spectral variation in the sensitivity of photosynthesis to inhibition by solar radiation in the globally important coccolithophore Emiliania huxleyi. Growth rates and chlorophyll a content per cell showed no significant differences between elevated (800 ppmv) and ambient (400 ppmv) CO2 conditions. However, the production of organic carbon and the cell quotas for both, carbon and nitrogen, increased under elevated CO2 conditions whilst particulate inorganic carbon production rates decreased under the same conditions. Biometric analyses of cells showed that coccoliths only presented significant differences due to treatments in the central area width. Most importantly, the size of the coccosphere decreased under elevated CO2 conditions. The susceptibility of photosynthesis to inhibition by ultraviolet radiation (UVR) was estimated using biological weighting functions (BWFs) and a model that predicts photosynthesis under photosynthetically active radiation (PAR) and UVR exposures. BWF results demonstrate that the sensitivity of photosynthesis to UVR was not significantly different between E. huxleyi cells grown under elevated and present CO2 concentrations. We propose that the acclimation to elevated CO2 conditions involves a physiological mechanism of regulation and allocation of energy and metabolites in the cell, which is also responsible for altering the sensitivity to UVR. In coccolithophores this mechanism might be affected by the decrease in the calcification rates. This article is protected by copyright. All rights reserved.
Contributors: Lewis, Carrie H. R., Richards-Zawacki, Corinne, Ibáñez, Roberto, Luedtke, Jennifer, Voyles, Jamie, Houser, Paul, Gratwicke, Brian
... Captive breeding programs are a valuable conservation strategy, particularly when integrated with research goals. Panamanian Harlequin frogs (genus Atelopus) serve as a case study for integrating captive breeding and research goals because they have experienced drastic chytridiomycosis-related declines and have large captive populations. Captive breeding efforts in Panama and the United States established secure ex-situ populations of Atelopus certus, A. glyphus, A. limosus, A. varius, and A. zeteki. Atelopus chiriquiensis is presumed to be extinct with no captive populations. The status of one undescribed species, Atelopus aff. limosus, has not been evaluated and no secure captive population has yet been established. Captive breeding efforts that produce a surplus of Atelopus are an important resource for research into collections management, disease mitigation, and adaptive management approaches for Atelopus reintroduction efforts. We reevaluated all Panamanian Atelopus species through the IUCN Redlist and compiled occurrence records for Panamanian Atelopus species to create a historical distribution map. We model Atelopus habitat suitability using Maxent and found annual mean air temperature to be the best predictor of Atelopus occurrence. The model will improve our knowledge of their likely spatial distribution and guide future conservation and reintroduction efforts. The recent proliferation of molecular tools, climate models, bio-banking, and reproductive technologies position us to address multiple applied and basic evolutionary questions such as: What factors cause differential disease outcomes? Do persisting populations have heritable traits associated with improved survivorship? Are there climatic refugia from disease? Ultimately, the answers to these questions will help us develop applied solutions and facilitate the reestablishment of self-sustaining wild populations.
Discovery of a Distinctive Spotted Color Pattern in the Cuskeel Neobythites unicolor (Teleostei, Ophidiidae) Based on Underwater-Vehicle Dives, with New Records from the Southern and Eastern Caribbean
Contributors: Uiblein, Franz, Nielsen, Jørgen G., Baldwin, Carole C., Quattrini, Andrea M., Robertson, D. Ross
... NH-Vertebrate Zoology
Contributors: Robertson, D. Ross, Baldwin, Carole C., Bellwood, David, Pyle, Richard, Smith-Vaniz, William, Tornabene, Luke, van Tassell, James L.
... NH-Vertebrate Zoology
Contributors: Muletz-Wolz, Carly, Fleischer, Robert C., Lips, Karen R.
... Pathogens compete with host microbiomes for space and resources. Their shared environment impacts pathogen-microbiome-host interactions, which can lead to variation in disease outcome. The skin microbiome of red-backed salamanders (Plethodon cinereus) can reduce infection by the pathogen Batrachochytrium dendrobatidis (Bd) at moderate infection loads, with high species richness and high abundance of competitors as putative mechanisms. However, it is unclear if the skin microbiome can reduce epizootic Bd loads across temperatures. We conducted a laboratory experiment to quantify skin microbiome and host responses (P. cinereus: n = 87) to Bd at mimicked epizootic loads across temperatures (13, 17, 21 °C). We quantified skin microbiomes using 16S rRNA gene metabarcoding and identified OTUs taxonomically similar to culturable bacteria known to kill Bd (anti-Bd OTUs). Prior to pathogen exposure, temperature changed the microbiome (OTU richness decreased by 12% and abundance of anti-Bd OTUs increased by 18% per degree increase in temperature), but these changes were not predictive of disease outcome. Post exposure, Bd changed the microbiome (OTU richness decreased by 0.1% and the abundance of anti-Bd OTUs increased by 0.2% per 1% increase in Bd load) and caused high host mortality across temperatures (35/45: 78%). Temperature indirectly impacted microbiome change and mortality through its direct effect on pathogen load. We did not find support for the microbiome impacting Bd load or host survival. Our research unravels complex host, pathogen, microbiome and environmental interactions to demonstrate that during epizootic events the microbiome will be unlikely to reduce pathogen invasion, even for putatively Bd-resistant species. This article is protected by copyright. All rights reserved.
Contributors: Piperno, Dolores R., McMichael, Crystal N. H., Bush, Mark B.
Contributors: Brandl, Simon J., Tornabene, Luke, Goatley, Christopher H. R., Casey, Jordan M., Morais, Renato A., Côté, Isabelle M., Baldwin, Carole C., Parravicini, Valeriano, Schiettekatte, Nina M. D., Bellwood, David R.
... How coral reefs survive as oases of life in low-productivity oceans has puzzled scientists for centuries. The answer may lie in internal nutrient cycling and/or input from the pelagic zone. Integrating meta-analysis, field data, and population modelling, we show that the ocean's smallest vertebrates, cryptobenthic reef fishes, promote internal reef-fish biomass production through exceptional larval supply from the pelagic environment. Specifically, cryptobenthics account for two-thirds of reef-fish larvae in the near-reef pelagic zone, despite limited adult reproductive outputs. This overwhelming abundance of cryptobenthic larvae fuels reef trophodynamics via rapid growth and extreme mortality, producing almost 60% of consumed reef fish biomass. While cryptobenthics are commonly overlooked, their unique demographic dynamics may make them a cornerstone of ecosystem functioning on modern coral reefs.
Growing season moisture drives interannual variation in woody productivity of a temperate deciduous forest
Contributors: Helcoski, Ryan, Tepley, Alan J., Pederson, Neil, McGarvey, Jennifer C., Meakem, Victoria, Herrmann, Valentine, Thompson, Jonathan R., Anderson-Teixeira, Kristina
... 1.The climate sensitivity of forest ecosystem woody productivity (ANPPstem ) influences carbon cycle responses to climate change. For the first time, we combine long-term annual growth and forest census data of a diverse temperate broadleaf deciduous forest, seeking to resolve whether ANPPstem is primarily moisture- or energy-limited and whether climate sensitivity has changed in recent decades characterized by more mesic conditions and elevated CO2 . 2.We analyzed tree-ring chronologies across 109 years of monthly climatic variation (1901-2009) for 14 species representing 97% of ANPPstem in a 25.6-ha plot in northern Virginia, USA. 3.Radial growth of most species and ecosystem-level ANPPstem responded positively to cool, moist growing season conditions, but the same conditions in the previous May-July were associated with reduced growth. In recent decades (1980-2009), responses were more variable and on average, weaker. 4.Our results indicate that woody productivity is primarily limited by current growing season moisture, as opposed to temperature or sunlight, but additional complexity in climate sensitivity may reflect the use of stored carbohydrate reserves. Overall, while such forests currently display limited moisture sensitivity, their woody productivity is likely to decline under projected hotter and potentially drier growing season conditions. This article is protected by copyright. All rights reserved.
Transcriptome profiling with focus on potential key genes for wing development and evolution in Megaloprepus caerulatus, the damselfly species with the world's largest wings
Contributors: Feindt, Wiebke, Oppenheim, Sara J., DeSalle, Robert, Goldstein, Paul Z., Hadrys, Heike