IAA22 Book of Abstracts (PDF)
Meeting Program/Schedule (PDF)
LIST OF MEETING ABSTRACTS
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Day: 3, Session: 2, Talk: 2
The Louisiana Crawfish History Summary, The Last Fifty Years
JAY V. HUNER, Robert P. Romaire, C. Greg Lutz, Albert P. Gaude III., James W. Avault Jr., W. Ray McClain and Mark G. Shirley
The Louisiana USA crawfish industry has two commercial sources of crawfish, Procambarus spp., a wild harvest, mostly from the Atchafalaya River Basin (ARB) in the south-central area of the state, and a cultivated harvest from aquaculture ponds, located primarily in the southwestern area of the state. The combined harvest in 2016 was 135.2 MT with aquaculture accounting for 91%. The modern crawfish aquaculture industry originated in the early 1960s when low water during the ARB spring flood resulted in a poor harvest. State biologists worked with farmers in the Mississippi River alluvial valley and the southwestern prairie area to cultivate crawfish in purpose built impoundments and rice field impoundments. Area in crawfish culture increased from 4,050 ha in 1968 to 90,050 ha in 2017. Aquaculture accounted for 40-60% of annual harvest until the year 2000 and thereafter accounted for 70-95%. Changes in the hydrology of the ARB have largely accounted for declining wild crawfish harvests. The dominant species is Procambarus clarkii, the red swamp crawfish. Some Procambarus zonangulus, the southern white river crawfish, are harvested. Three major events impacted the Louisiana crawfish industry. First, import of crawfish products from the Peoples’ Republic of China beginning in the mid-1990s lowered prices. Second, an insecticide applied to rice fields used to cultivate crawfish in 1999-2001, combined with historical record summer drought which negatively impacted reproduction, led to widespread crop failure. Third, White Spot Shrimp Virus (WSSV), highly lethal to Procambarus spp. became widely distributed in both wild and cultured crawfish crops. Initially, competition from Chinese crawfish products had a negative impact on the Louisiana crawfish industry. However, over time imports led to development of new domestic markets and industry wide quality control practices. The highest crawfish production cost is harvesting – labor and bait. Crawfish are harvested in mesh traps that must be tended manually. Mechanized harvest boats have reduced the time necessary to tend traps but trapping is still highly inefficient. Initially, cut rough fish was the common bait, and later grain-based manufactured baits were developed but are relatively ineffective during colder months of the November/December – May/June seasons. A short-lived soft-shelled crawfish industry involving as many as 150 farmers developed in the 1980s. Despite good acceptance of the product, profits were low and entrepreneurs left the trade. No more than three producers remain today. Crawfish are cultivated by simulating the cool season wet, warm season dry hydrology of Louisiana. This works so well with rice farming that 75% of crawfish area is integrated with rice. The agricultural community refers to this landscape as working wetlands. The food rich system attracts predaceous, omnivorous, and vegetarian species of birds in great numbers. As a result, the National Audubon Society has designated the southwestern Louisiana region as an Important Bird Area of Global Importance. However, concerns about bird impacts on crawfish crops remain.
Day: 3, Session: 4, Talk: 3
Epigenetic Regulation in the Marbled Crayfish
VITOR COUTINHO CARNEIRO, Anny Gatzmann, Cassandra Falckenhayn and Frank Lyko
The all-female marbled crayfish (Procambarus virginalis) attracted the attention of the scientific community due to its 'self-cloning' capacity. The obligatory parthenogenetic reproduction provided interesting research opportunities and also established a potent ecological threat. Despite its identical DNA, this model has an extraordinary variety in appearance and behaviour between isogenic batchmates reared in the same environment. This suggests that epigenetic mechanisms play a key role in marbled crayfish phenotypic variation. Our group has recently annotated the draft genome of the marbled crayfish, which revealed a conserved, functional and versatile DNA methylation system for epigenetic regulation. We have also used whole-genome bisulfite sequencing, RNA-seq and ATAC-seq for a comprehensive analysis of multiple individuals and tissues. Our results provide a novel concept for how methylation-dependent regulation of gene expression may facilitate the phenotypic adaptation and invasive spread of this animal.
Development of a Captive Rearing Protocol for Threatened & Endangered Appalachian Crayfish
CHRISTOPHER VOPAL, Emmy Delekta and Zachary J. Loughman
In 2016, two Appalachian endemic species were federally listed by the United States Fish & Wildlife Service: Cambarus callainus (Big Sandy Crayfish) and Cambarus veteranus (Guyandotte River Crayfish), which are listed as threatened and endangered respectively. Both species were listed due to limited and declining ranges caused by various anthropogenic activities, especially those causing stream sedimentation. Captive propagation can be used as a tool for crayfish conservation by helping to restore the native range of a species or improving their fecundity within their current range. Over a ten week period, 120 young-of-the-year (YOY) Cambarus chasmodactylus (New River Crayfish), a surrogate species for C. callainus and C. veteranus, were raised in individual cells to compare (1) growth and (2) survival on two different diets. They were fed every other day, with half (60) raised on trout diet pellets (TD) and the other half raised on blood worms (BW). Results showed more YOY growth with BW (17.3% growth) than with TD (13.6% growth). Increased survival was also observed with BW (84.5% survival) when compared to the TD (70.5% survival). Our results may be influenced by the ease and ability for the crayfish to forage on the blood worms and may also have a higher nutritional value in comparison to the TD. Our findings suggests a BW diet may be more effective in the captive rearing of Camabrus crayfish. Using information gathered from this study, a modified protocol will be used for a new study beginning July 2018 for C. callainus and Cambarus smilax (Greenbrier Crayfish). This modified protocol will compare three diets (bloodworm, detritus, and bloodworm/detritus) in the growth and survival of YOY C. callainus and C. smilax in a six month period.
Exploring the Limit and Beyond of Hypoxia: Behavioural-driven Conservation of an Ancestral Legacy of Freshwater Crayfish
LUCIAN PÂRVULESCU, Adrian Neculae, Eva Kaslik, Claudia Zaharia, Zanethia Barnett, Marcelo M. Dalosto, James M. Furse, Tadashi Kawai, Sandro Santos and Ovidiu I. Sîrbu
Freshwater crayfish burrowing is not simply sheltering, but an active and conscious behavior in which the animal invests considerable time and energy. As aerobic organisms, crayfish are often recorded as being related to high levels of dissolved oxygen. Approaches considering the in-burrow requirements of oxygen are scarce. We monitored the respiratory behavior and survival under acute hypoxia under controlled conditions in the laboratory of ten ecologically and phylogenetically dissimilar species of crayfish from different geographical locations (5 species of Cambaridae, 3 of Astacidae and 2 of Parastacidae). We found that primary burrowing species (Parastacus brasiliensis and Cambarus striatus) cannot tolerate severe hypoxia, whereas secondary and tertiary burrowing species (Faxonius limosus, F. etnieri, Procambarus vioscai, Cambaroides japonicus, Austropotamobius torrentium, Astacus leptodactylus, A. astacus and Cherax quadricarinatus) were not only able to withstand prolonged anoxia, but also able to remain active for up to 40 hours after reaching zero-oxygen conditions. Using nonlinear regression tools applied to the available experimental data, we estimated the critical values of the dissolved oxygen levels which characterize the transition from aerobic to anaerobic respiration for each species found tolerating the anoxia. Based on the diffusion-convection transport and the experimentally determined oxygen consumption function, we developed a mathematical model describing the time-dependent changes of the dissolved oxygen concentration which takes into account both aerobic and anaerobic respiratory processes for A. leptodactylus and O. limosus in a virtual burrow filled with water. We further validated our models by comparing numerical simulations with laboratory measurements for different geometries of burrows. Excluding a region at the entrance, the mathematical predictions for a normal day-night cycle of a crayfish inside a (virtual) burrow show that the water-dissolved oxygen inside the burrow reaches anoxia levels within hours. We speculate that the ability of crayfish to cope with oxygen shortages might be a phylogenetic legacy from their ancestors, lobsters, known to encounter low levels of oxygen in deep waters. Most probably, the primary burrowing species lost this ability since the oxygen diffusion is much faster in fossorial burrows, and thus leading to weaker conservation of the specific mechanisms during evolution. These results challenge the current behavioral and physiological knowledge of crayfish, and might drive new perspectives on the ecology, conservation and even evolutionary processes.
Influence of Climate Warming on the Ecological Impacts of Invasive Crayfishes
VICTORIA CHICATUN and Anthony Ricciardi
Aquatic systems in temperate regions are particularly sensitive to temperature change, which can cause seasonal stress for cold-water adapted species and hospitable conditions for warm-water invaders. Altered thermal regimes may mediate the ecological impacts of non-native species by affecting their abundance and per capita effects, causing shifts in predator-prey dynamics and competitive dominance over native species. High-impact invaders tend to exhibit higher functional responses (maximum feeding rates) than functionally-similar native taxa. It has also been shown that individuals' maximum feeding rates are inversely proportional to the deviation from their environmental optima and could potentially be used a performance metric for invasive species across a thermal gradient. My research investigates the effects of water temperature and population latitude on prey consumption and competitive dominance by invasive (Faxonius rusticus) and native (F. virilis) crayfishes in the Great Lakes basin. For this, I have planned a series of lab experiments comparing functional responses and outcomes of competitive interactions across temperatures (based on projected warming scenarios for the lower Great Lakes) to test the prediction that native species will exhibit lower maximum feeding rates than invaders and that increasing temperatures will result in competitive dominance of southern species over northern species.
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