Tracy A Valerius (nee Ziegler) | Duke University (original) (raw)

Papers by Tracy A Valerius (nee Ziegler)

Critical Reviews in Environmental Science and Technology, 2021

Associated health effects from algal toxin exposure are a growing concern for human and animal he... more Associated health effects from algal toxin exposure are a growing concern for human and animal health. Algal toxin poisonings may occur from contact with or consumption of water supplies or from ingestion of contaminated animals. The U.S. Federal Government owns or holds in trust about 259 million hectares of land, in addition to the Trust species obligations. We completed the first comprehensive review of potential toxin-producing algal blooms in surface waters on Federal lands and Trust species exposed to algal toxins. Events were sorted into three tiers based on potentially toxic algae abundance or toxin concentration and related effects on animal morbidity and mortality. At least 11.1% of Federal lands are known to have been affected by algal events, but exposure is likely underreported. The occurrence of potential toxin producers and their toxins (Tier 1) have been documented 337 times, health advisory threshold exceedances (Tier 2) were reported 943 times, and 86 events involved animal sickness or death linked to cyanobacteria or marine toxins (Tier 3). Trust species exposed to cyano- or algal toxins included marine mammals, migratory birds, threatened and endangered species, and species of concern. We report numerous data gaps ranging from potential effects on human health from consuming intoxicated animals to the infrequency of measuring and reporting certain toxins. Improvements to field and laboratory methods, more consistent evaluation of toxin exposure, decreased latency on data analysis, delivery and interpretation will be necessary to improve response and management strategies for protecting human and animal health where issues persist.

Critical Reviews in Environmental Science and Technology, Dec 10, 2021

The Biological Bulletin, Dec 1, 2010

Phyllosoma larvae of the spiny lobster Panulirus argus undergo diel vertical migration (DVM), in ... more Phyllosoma larvae of the spiny lobster Panulirus argus undergo diel vertical migration (DVM), in which they are at depth during the day and nearer the surface at night. This study determined the visual spectral sensitivity of Stage I larvae and investigated whether light plays a proximate role in DVM as an exogenous cue and as an entrainment cue for an endogenous rhythm in vertical migration. Under constant conditions, larvae have a circadian rhythm (24.5-h period) in vertical swimming that resulted in a twilight DVM pattern. The behavioral response spectrum and electroretinogram recording indicated two photoreceptor spectral classes with maxima at 360 and 486 nm. When stimulated in an apparatus that simulated the underwater angular light distribution, dark-adapted larvae showed only positive phototaxis, with a threshold intensity of 1.8 ϫ 10 13 photons m-2 s-1 (3.0 ϫ 10-5 moles photons m-2 s-1). They have an avoidance response to predator shadows in which they descend upon sudden decreases in light intensity of more than 69%. When stimulated with relative rates of decrease in light intensity as occur at sunset they ascended, whereas they descended upon relative rates of light intensity increase as occur at sunrise. Thus, the DVM pattern is controlled by both an endogenous circadian rhythm in swimming and behavioral responses to light at sunrise and sunset.

The Biological Bulletin, Dec 1, 2005

Ovigerous mole crabs Emerita talpoida (Say) were monitored in the laboratory to determine if the ... more Ovigerous mole crabs Emerita talpoida (Say) were monitored in the laboratory to determine if the time of larval release is synchronous and under endogenous control. To determine the time of larval release, ovigerous females were placed under a 14:10 light/dark cycle simulating the ambient photoperiod. Hatching was rhythmic, occurring as a quick burst lasting about 5-15 min shortly after the onset of darkness. An individual mole crab will release batches of larvae for up to three successive nights, suggesting that the rhythm is under endogenous control. Mole crabs monitored under constant low-level red light displayed the same release pattern with hatching occurring near the time of expected sunset, indicating the presence of a circadian rhythm in larval release. To investigate whether the female or the embryos control hatching, a portion of the egg mass (50-100 embryos) was separated from the female. The time of hatching of the detached embryos subjected to either a still or shaken treatment was compared with the hatching time of embryos still attached to the female. Detached eggs in both treatments hatched within 1.5-2 h of the time of the femaleattached eggs, which suggests that embryos control the timing of hatching.

Journal of Chemical Ecology, Jul 20, 2007

Larval release in the Caribbean spiny lobster Panulirus argus is highly synchronous and is contro... more Larval release in the Caribbean spiny lobster Panulirus argus is highly synchronous and is controlled by a &amp;amp;amp;amp;amp;amp;amp;quot;pumping pheromone&amp;amp;amp;amp;amp;amp;amp;quot; released from the hatching eggs. The pheromone induces a parent female to undergo stereotypical larval release behaviors, including rapid abdominal extensions and pleopod pumping. These behaviors help to break open the egg membranes and result in the synchronous release of larvae. Based on previous studies on larval release in brachyuran crabs, we hypothesized that larval release behaviors are induced by pheromones composed of small peptides. We quantified pleopod pumping activity upon exposure to a range of synthetic peptides to identify compounds that will induce larval release behaviors. Chemically cued pumping behavior was described in terms of the threshold concentration for response, maximum percentage response, and effective concentration range. Pleopod pumping behavior was evoked by di- and tripeptides with a neutral amino acid at the amino terminus and a basic amino acid at the carboxy terminus and also by the basic-basic dipeptide Lys-Arg. All carboxy-terminal arginine peptides tested produced a significant pumping response, with the exception of Trp-Ile-Arg. Response concentration thresholds ranged from 10(-9) M for the most potent peptide (Gly-Arg) to 10(-4) M for the least potent (Gly-His-Lys). The maximum percentage of lobsters responding was largely independent of the threshold concentration and ranged from 24.3 to 58.3%. Effective concentration ranges for the peptides were variable from 1 to 4 orders of magnitude. Pumping response usually declined with increasing concentration beyond the concentration that evoked the maximum response of the peptides. Our results support the conceptual model that larval release in subtidal crustaceans is controlled by small peptides that act as pheromones.

Journal of Experimental Marine Biology and Ecology, Aug 1, 2006

... laboratory conditions, where the animal is not receiving external environmental cues, will co... more ... laboratory conditions, where the animal is not receiving external environmental cues, will continue to release larvae near the time of expected high tide or darkness (eg, [Ennis, 1973] , [Ennis, 1975] , [Branford, 1978] , [Moller and Branford, 1979] , [Bergin, 1981] , [Forward et al ...

Marine Biology, May 16, 2007

The current model for larval release in subtidal crustaceans suggests that hatching time is contr... more The current model for larval release in subtidal crustaceans suggests that hatching time is controlled by the embryos, which release a pheromone that stimulates the parent female to undergo behaviors that synchronize larval release. Alternatively, hatching could be controlled by the females. Ovigerous spiny lobsters Panulirus argus (Latreille) exhibit stereotypic behaviors during larval release, including rapid abdominal extensions and pleopod-pumping activity. Ovigerous P. argus were collected from coral reefs in the Florida Keys, USA during the summers of 2005 and 2006. Pleopod-pumping activity was quantiWed to determine if a female's pumping activity correlates with the developmental state of the embryos. The role of pheromones released by developing and hatching embryos in controlling pumping behaviors was tested by measuring the pumping response of ovigerous lobsters to (1) hatch water, (2) homogenized embryo water, (3) embryo-conditioned water (unhatched late-stage embryos soaked for 20 h), and (4) water containing homogenized post-hatch embryo cases. Bioassays were conducted under constant conditions (dim-red light) in the laboratory at random times during the day to control for any possible rhythm in pumping activity. Spontaneous pleopod-pumping activity increased signiWcantly with increasing embryo development. Upon exposure to hatch water, ovigerous lobsters with late-stage embryos displayed increased pleopod pumping with increased treatment concentration. Water individually conditioned with homogenized late-stage embryos, intact late-stage embryos, and homogenized post-hatch embryo cases all induced larval release behaviors in females with late-stage embryos. Ovigerous females with early-stage embryos did not respond to water conditioned with homogenized early-or late-stage embryos. These results suggest that active substances are released by embryos at the time of hatching and induce the stereotypical pumping behaviors of the female that synchronizes larval release. The results support the model that larval release in subtidal crustaceans is controlled by pheromones released from hatching embryos.

This dissertation investigated larval release and larval behavior of the Caribbean spiny lobster ... more This dissertation investigated larval release and larval behavior of the Caribbean spiny lobster Panulirus argus and the spotted spiny lobster P. guttatus. These species were examined under laboratory conditions to determine the phase relationship between larval release and natural environmental cycles. P. argus displayed a nocturnal tidal rhythm, while P. guttatus displayed a circadian rhythm in larval release. P. argus releases larvae near the time of nocturnal high slack water, while P. guttatus released larvae near the time of sunrise. The role of 'pumping pheromones' in controlling larval release behaviors was tested by measuring the pumping response of ovigerous P. argus to (1) hatch water, (2) homogenized-embryo water, (3) embryo-conditioned water, and (4) water containing homogenized-egg cases. Lobsters with late-stage embryos displayed increased pleopod pumping with increased concentration of hatch water. Water individually conditioned with homogenized late-stage embryos, intact late-stage embryos, and homogenized eggcases induced pumping activity in females with late-stage embryos, indicating the presence of a chemical cue. I quantified pumping responses upon exposure to synthetic peptides to determine if they mimicked pheromones that induce larval release behaviors. Pumping behavior was evoked by oligopeptides with a basic amino acid at the carboxy-terminus, v preceded by several neutral amino acids. Carboxyl-terminal arginine peptides serve as pheromone mimics. I investigated whether these peptides originate from the action of trypsin-like enzymes by conducting a bioassay measuring pumping activity of ovigerous P. argus subjected to increasing concentrations of trypsin, trypsin inhibitor, and a combination of the two. Pumping activity increased with increasing concentrations of trypsin and trypsin inhibitor, while behaviors ceased when ovigerous females were subjected to a complex of the two. Pheromones are generated by trypsin-like enzymes assisting in the degradation of the egg membranes at the time of hatching. Vertical swimming behaviors of stage-I phyllosoma larvae of P. argus and P. guttatus were observed under laboratory conditions. P. argus larvae displayed a pattern of twilight vertical migration, while P. guttatus larvae displayed nocturnal diel vertical migration (DVM). Rhythms persisted for 5-6 cycles under constant conditions, indicating that an endogenous rhythm in activity plays a proximate role in DVM for both species. vi Dedication This work is dedicated to the memories of my father, Charles A. Ziegler II, my sister Christine J. Ziegler, my aunt Susan F. Holl, and my best friends Loretta D. Abel

In Florida's remote Dry Tortugas National Park, coral reefs are an important management priority.... more In Florida's remote Dry Tortugas National Park, coral reefs are an important management priority. Reproduction of coral species is difficult to monitor, however, and the reproductive potential of coral colonies at the park has been a matter of concern for several years. Two threatened species, elkhorn coral (Acropora palmata) and pillar coral (Dendrogyra cylindrus), were targeted for observation during their predicted annual spawning event in August 2014. Over a three-night period, both species were observed releasing gametes in near synchrony with observations at other sites in the Florida Keys. That these organisms are capable of being reproductive within the park provides hope for the future of these threatened species in the region.

Fisheries Research, Jul 1, 2013

The Dry Tortugas Research Natural Area (RNA), a 158-km 2 no-fishing, no-anchor marine reserve, wa... more The Dry Tortugas Research Natural Area (RNA), a 158-km 2 no-fishing, no-anchor marine reserve, was implemented in 2007 in Dry Tortugas National Park (DRTO), Florida to minimize the effects of human activities on marine resources and to enhance the productivity and sustainability of fish populations. The process of establishing the RNA resulted in the development of a Memorandum of Understanding (MOU) between the State of Florida and the National Park Service (NPS). The MOU constitutes a roadmap for the roles and responsibilities for a state and federal partnership, collaborative preparation of a research and monitoring plan, and reporting on the progress implementing the plan and preliminary findings. A science plan was developed in conjunction with marine and fisheries scientists from multiple agencies and non-government organizations to: (1) quantify changes in the abundance and size-structure of exploited fish species within the RNA relative to adjacent areas; (2) monitor the immigration and emigration of targeted species; (3) monitor changes in species composition and catch rates of exploited fish species throughout the surrounding region; (4) evaluate the effects on marine benthic biological communities; (5) assess reproductive potential of exploited fish species by evaluating egg production and larval dispersal; and (6) implement social science studies to evaluate visitor experiences. For each topic, performance measures, essential and supplemental activities, and general study recommendations were developed. The plan supported interagency marine resource managers in the structured implementation of a science program by communicating to the public a suite of performance measures and essential and supplementary studies designed to document changes in fisheries resources. Development of collaborative marine science programs are useful for leveraging resources, engaging the public and agency decision-makers, and long-term planning to ensure that research and monitoring data are available for sustainable adaptive management of marine reserves.

Critical Reviews in Environmental Science and Technology

In Florida’s remote Dry Tortugas National Park, coral reefs are an important management priority.... more In Florida’s remote Dry Tortugas National Park, coral reefs are an important management priority. Reproduction of coral species is difficult to monitor, however, and the reproductive potential of coral colonies at the park has been a matter of concern for several years. Two threatened species, elkhorn coral (Acropora palmata) and pillar coral (Dendrogyra cylindrus), were targeted for observation during their predicted annual spawning event in August 2014. Over a three-night period, both species were observed releasing gametes in near synchrony with observations at other sites in the Florida Keys. That these organisms are capable of being reproductive within the park provides hope for the future of these threatened species in the region.

Fisheries Research, 2021

Government and private organizations in many regions invest heavily in artificial reefs as a meth... more Government and private organizations in many regions invest heavily in artificial reefs as a method of enhancing fish populations for recreational fishermen. Though these reefs are known to aggregate fish in the short-term, the long-term maintenance of elevated fish abundance may be impaired as a result of succession to an unpalatable benthic community. We tested the hypothesis that providing a spatial refuge for benthic fauna would result in elevated fish abundances on artificial reefs. Sturdy mesh bags that excluded fish predators and created a growth and reproductive refuge for fouling organisms were placed into artificial reef materials at four replicate sites off the North Carolina coast. Reef sites were subsequently surveyed using two methods: diver fish counts and professional angler success. Anglers consistently demonstrated greater catch rates on reefs with refuge bags. Diver surveys after one year also showed that total abundance of fish as well as abundance of several spe...

This study describes aspects of the biology of heat shock proteins 90kDa (hsp90) in terrestrial d... more This study describes aspects of the biology of heat shock proteins 90kDa (hsp90) in terrestrial decapods, Coenobita purpureus, C. brevimanus (Anomura: Coenobitidae) and Chiromantes haematocheir (Brachyura: Sesarmidae). These species possess highly developed terrestrial adaptations on both morphological and physiological levels. We have analyzed the pattern of expression for the gene coding hsp90: molecular chaperon in both embryos and the muscle tissues of adults of these species in response to heat stress. While the minimum temperature for initiation of the synthesis of excess of hsp90 mRNA was different between embryos and adults from the different climatic regions, the range of resistance to high temperature shock was nearly the same (6-7°C). Furthermore, the structure of the stress-factor binding domain in hsp90 coding gene showed convergent patterns by possessing a conservative amino acid sequence in decapods experiencing the same annual temperature regimes in the subtropical, temperate and boreal climatic regions.