Kevin Fitzsimmons

Determination of the infectious nature of the agent of acute hepatopancreatic necrosis syndrome affecting penaeid shrimp.

A new emerging disease in shrimp, first reported in 2009, was initially named early mortality syndrome (EMS). In 2011, a more descriptive name for the acute phase of the disease was proposed as acute hepatopancreatic necrosis syndrome (AHPNS). Affecting both Pacific white shrimp Penaeus vannamei and black tiger shrimp P. monodon, the disease has caused significant losses in Southeast Asian shrimp farms. AHPNS was first classified as idiopathic because no specific causative agent had been identified. However, in early 2013, the Aquaculture Pathology Laboratory at the University of Arizona was able to isolate the causative agent of AHPNS in pure culture. Immersion challenge tests were employed for infectivity studies, which induced 100% mortality with typical AHPNS pathology to experimental shrimp exposed to the pathogenic agent. Subsequent histological analyses showed that AHPNS lesions were experimentally induced in the laboratory and were identical to those found in AHPNS-infected shrimp samples collected from the endemic areas. Bacterial isolation from the experimentally infected shrimp enabled recovery of the same bacterial colony type found in field samples. In 3 separate immersion tests, using the recovered isolate from the AHPNS-positive shrimp, the same AHPNS pathology was reproduced in experimental shrimp with consistent results. Hence, AHPNS has a bacterial etiology and Kochs Postulates have been satisfied in laboratory challenge studies with the isolate, which has been identified as a member of the Vibrio harveyi clade, most closely related to V. parahemolyticus.

Effect of elevated CO2 on the community metabolism of an experimental coral reef

[1]xa0The effect of elevated pCO2 on the metabolism of a coral reef community dominated by macroalgae has been investigated utilizing the large 2650 m3 coral reef mesocosm at the Biosphere-2 facility near Tucson, Arizona. The carbonate chemistry of the water was manipulated to simulate present-day and a doubled CO2 future condition. Each experiment consisted of a 1–2 month preconditioning period followed by a 7–9 day observational period. The pCO2 was 404 ± 63 μatm during the present-day pCO2 experiment and 658 ± 59 μatm during the elevated pCO2 experiment. Nutrient levels were low and typical of natural reefs waters (NO3− 0.5–0.9 μM, NH4+ 0.4 μM, PO43− 0.07–0.09 μM). The temperature and salinity of the water were held constant at 26.5 ± 0.2°C and 34.4 ± 0.2 ppt. Photosynthetically available irradiance was 10 ± 2 during the present-day experiment and 7.4 ± 0.5 mol photons m−2 d−1 during the elevated pCO2 experiment. The primary producer biomass in the mesocosm was dominated by four species of macroalgae; Haptilon cubense, Amphiroa fragillisima, Gelidiopsis intricata and Chondria dasyphylla. Algal biomass was 10.4 mol C m−2 during the present-day and 8.7 mol C m−2 and during the elevated pCO2 experiments. As previously observed, the increase in pCO2 resulted in a decrease in calcification from 0.041 ± 0.007 to 0.006 ± 0.003 mol CaCO3 m−2 d−1. Net community production (NCP) and dark respiration did not change in response to elevated pCO2. Light respiration measured by a new radiocarbon isotope dilution method exceeded dark respiration by a factor of 1.2 ± 0.3 to 2.1 ± 0.4 on a daily basis and by 2.2 ± 0.6 to 3.9 ± 0.8 on an hourly basis. The 1.8-fold increase with increasing pCO2 indicates that the enhanced respiration in the light was not due to photorespiration. Gross production (GPP) computed as the sum of NCP plus daily respiration (light + dark) increased significantly (0.24 ± 0.03 vs. 0.32 ± 0.04 mol C m−2 d−1). However, the conventional calculation of GPP based on the assumption that respiration in the light proceeds at the same rate as the dark underestimated the true rate of GPP by 41–100% and completely missed the increased rate of carbon cycling due to elevated pCO2. We conclude that under natural, undisturbed, nutrient-limited conditions elevated CO2 depresses calcification, stimulates the rate of turnover of organic carbon, particularly in the light, but has no effect on net organic production. The hypothesis that an increase pCO2 would produce an increase in net production that would counterbalance the effect of decreasing saturation state on calcification is not supported by these data.

Halophytes for the treatment of saline aquaculture effluent

We determined the feasibility of using salt-tolerant plants (halophytes) as biofilters to remove nutrients from saline aquaculture wastewater. Suaeda esteroa, Salicornia bigelovii and Atriplex barclayana (Chenopodiaceae), species with potential as forage and oil seed crops, were grown in sand in draining containers (lysimeters) in a greenhouse experiment. They were irrigated to meet evapotranspiration demand and to produce a 0.3 leaching fraction, using aquaculture effluent generated from an intensive tilapia culture system. The effluent salinity was increased with NaCl to make salinity treatments of 0.5, 10 and 35 ppt. The plant–soil system removed 98% and 94% of the applied total and inorganic nitrogen, respectively. It removed 99% and 97% of the applied total and soluble reactive phosphorus, respectively. High removal rates occurred despite the high leaching fraction. Salt inhibited (P<0.05) the growth rate, nutrient removal, and volume of water that all three plant species could process. Suaeda and Salicornia, which are succulent salt marsh species, performed better than the desert saltbush, Atriplex, at the higher salinities.

Tilapia Production Systems in the Americas: Technological Advances, Trends, and Challenges

Tilapia is the common name applied to three genera of fish in the family Cichlidae: Oreochromis, Sarotherodon, and Tilapia. The species that are most important for aquaculture are in the genus Oreochromis, including the Nile tilapia, O. niloticus, the Mozambique tilapia, O. mossambicus, the blue tilapia, O. aureus, and O. urolepis hornorum. Fish farmers are now growing many strains of these parent species along with many hybrid strains. Native to Africa and the Middle East, these species have become the second most common farm raised food fish in the world. In the 1960s and 1970s tilapia culture was aimed at the production of food for local consumption, utilizing primarily extensive or semiintensive culture methods with minimal inputs of fertilizer or feeds. However, tilapia culture has expanded rapidly during the last decade as a result of technological advances associated with the intensification of culture practices. These include the development of new strains and hybrids, monosex male culture, formulated diets, a variety of semiintensive and intensive culture systems (e.g., ponds, cages, tanks, and raceways) and the utilization of greenhouses, geothermal, or industrial waste heat and advanced water treatment methods. Marketing programs have also nurtured a growing demand for tilapia in domestic and international markets. Annual worldwide production of cultured tilapia was less than 200,000 metric tons (mt) in 1984 and increased to 1,100,000 mt in 1999. In the Americas, the increased production of farmed tilapia is due in large part to their adaptability to a diverse array of production systems. These include subsistence level, extensive pond culture in the Eastern Caribbean, integrated animal-fish culture in Guatemala and Panama, semiintensive pond culture in Honduras, intensive pond culture in Colombia, Costa-Rica and Jamaica, semiintensive cage culture in several countries, intensive flowthrough tank and raceway culture in the U.S., and a variety of highly intensive indoor recirculating tank culture in the U.S. In addition, there is increasing production of tilapia in shrimp ponds in Ecuador to ameliorate shrimp disease problems. In this article, representatives of various systems are compared with respect to technological approaches and constraints. Poor management of tilapia genetic resources is causing a loss of productivity, and research in genetics and selective breeding will be needed to improve production efficiency, fillet yields, and environmental tolerance. Continuing nutritional studies will also be needed to increase efficiency and profitability. With intensification, infectious diseases have become more serious, and fish health management through biosecurity procedures, environmental manipulation, reduction of stress, nutrition, genetics, and the use of prophylactic therapeutics will be essential. Increasing waste production will require novel methods for integrating tilapia culture with the production of other valuable crops to maximize nutrient recovery and minimize pollution. Market development and quality control will be critical to ensure market growth.

Characterization of effluent from an inland, low-salinity shrimp farm: what contribution could this water make if used for irrigation

Coastal aquaculture can contribute to eutrophication of receiving waters. New technologies and improved management practices allow the aquaculture industry to be more sustainable and economically viable. Current practices, however, do not provide an additional use for effluent water. Nitrogen, phosphorus and other effluent compounds could be valuable plant nutrients. Inflow and effluent water from an inland, low-salinity shrimp farm, were monitored. Bi-weekly analysis included total nitrogen, ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, total phosphorus, reactive phosphorus, alkalinity, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS) and volatile suspended solids (VSS), as well as temperature, salinity, dissolved oxygen and pH. Alkalinity and total nitrogen decreased during the in-pond residency. The other parameters increased while in the ponds. The potential benefit of having nutrient enriched wastewater to irrigate field crops was substantial, supplying between 20 and 31% of the necessary nitrogen fertilizer for wheat production.

Spore culture of the edible red seaweed, Gracilaria parvispora ( Rhodophyta)

Abstract A hatchery was established for the inoculation of coral chips, pebbles and lines with carpospores of Gracilaria parvispora , an edible market seaweed in Hawaii. Cystocarpic thalli were placed over various substrates in tanks of aerated seawater. Carpospores attached readily to substrates and after 72 h in hatchery tanks, mean spore density on slides placed in hatch tanks was 1800 cm −2 . Inoculated coral chips and pebbles were placed out in a seawater pond. After 18–22 weeks spore density declined to 4 cm −2 but 61% of substrates still had plants. Only 36% of inoculated lines developed good growth, but growth was more rapid on lines than on pebble or chips. Lines yielded two crops per year, each approximately 800 g m −2 (fresh weight), whereas chips and pebbles required 50 weeks growth for an equivalent harvest. Tetrasporophytes were the dominant adult stage but cystocarpic plants accounted for approximately 10% of the culture products, demonstrating that the life cycle of this species was completed within the culture system. Spore culture of Gracilaria allowed mass production of plants on a variety of artificial substrates but the disadvantages included the long lag period and the lower reliability compared with vegetative production methods.

A sustainable culture system for Gracilaria parvispora (Rhodophyta) using sporelings, reef growout and floating cages in Hawaii

Abstract A culture system for the edible, red seaweed, Gracilaria parvispora Abbott (long ogo), was developed in Hawaii that utilized a hatchery to produce tetrasporophyte and gametophyte life stages of the seaweed, reef growout of sporelings to harvest size adults, and multiplication of the harvested thalli in floating cages prior to sale. A central cooperative operated the hatchery and floating cages, and marketed the product. Sporelings from the hatchery were distributed to coastal residents who established patches of seaweed on the reef and sold their harvest to the cooperative. Mean relative growth rate of seaweed in the cages over 52 weeks was 2.64% d −1 and productivity was 14.8 g m −2 d −1 (dry weight), within the range of intensive culture systems. Cage cultures were not sensitive to water motion over the range of 4–14 cm s −1 but growth and productivity tended to be higher in summer and spring than in winter. The culture system potentially overcomes problems that have hindered development of a sustainable supply of this species: low availability of wild stocks due to overharvesting; low productivity of spore cultures; and deterioration of vegetative cultures over time. Some of the elements may be applicable to other areas where wild stocks of Gracilaria have been overharvested.

Science and policy dilemmas in the management of agricultural waste waters: the case of the Salton Sea, CA, USA

Abstract The Salton Sea in California, a repository for agricultural drainage water and sewage effluent from the United States and Mexico, is increasing in salinity and may soon be too saline to support fish and other elements of the present food chain. Massive fish kills and bird die-offs in recent years have led to a perception that this is an ecosystem in trouble, and an initiative to restore the Salton Sea is underway. Engineering proposals to stabilize the salinity and volume of the Salton Sea could cost a billion dollars or more to install and ten million dollars per year or more to operate, and could adversely affect adjacent ecosystems, with no certainty that the problems of the sea would be remedied. On the other hand, allowing salinity to increase will likely lead to a dramatic change in the species composition of the sea over the next two decades. We consider the possible ecological consequences of allowing salinity to increase in the Salton Sea to levels similar to other salt lakes in the region. We also consider the possible adverse ecological affects of engineering proposals which would discharge contaminated Salton Sea water into the Gulf of California or divert excess Colorado River water that now flows to the Colorado River delta to the Salton Sea. We consider the benefits of an alternative proposal, which would handle the problem within the Salton Basin by installing designed wildlife habitats around the Sea while allowing the main body to become hypersaline. We recommend a set of principles which should guide policy decisions regarding restoration of the Salton Sea.

Halophyte irrigation: an overlooked strategy for management of membrane filtration concentrate

It is argued that the preferred paradigm for utilizing membrane filtration concentrate conceptually, and legally in Arizona, is to view it as an agricultural water management opportunity rather than a wastewater disposal problem. Halophyte farms irrigated with concentrate at a 5% leaching rate are projected to be productive for over 100y in southern Arizona without affecting the quality of the underlying groundwater any more than conventional agriculture. The authors recommend that halophyte irrigation be included in the management options for membrane filtration concentrate at current and future sites.

Inland saline aquaculture.

Abstract: Increasing demand for aquaculture has led to the development of new production systems. Inland saline aquaculture, defined here as land-based aquaculture using saline groundwater, occurs in several countries including Israel, the USA, India and Australia. A number of species are cultured, or are being evaluated for their potential, including finfish such as tilapia, Asian sea bass and trout, shrimp and oysters. Sources of saline groundwater include ephemeral and permanent saline lakes, saline water extracted with coal seam gas and saline groundwater extracted from aquifers. Saline groundwater is extracted in some areas to protect the root zone of plants. Characteristics of saline-affected land are described, with particular focus on Australia and India. Another emerging source of saline groundwater is the coal bed methane gas industry. Saline water accompanies extraction of the gas and, while it can be a major environmental problem for the gas industry, it presents an opportunity for aquaculture. Saline groundwater can differ in chemistry compared with coastal seawater and adjusting the chemistry or choosing species that are tolerant to the differences is one of the major challenges for expansion of inland saline aquaculture. The chemistry of different sources of water is described and common methods of adjusting the chemistry described. Finally, case studies of inland saline aquaculture are presented for Australia, India, Israel and the USA. Novel food production methods, such as inland saline aquaculture, are needed to increase aquaculture production and meet increasing demands for seafood.