Aquatic Animal Health Management

Currently Ethiopian higher institution curriculums are harmonized to a modular system which is ought to improve and maintain the quality of education. In newly opened institutions like Wollega University, who engaged in training of various Veterinary health professionals for which there is shortage of references materials, preparation of standard lecture notes and modules is indisputable. Therefore, with in the module of the curriculum, this lecture note was developed on the course “Animal Health Extension and Pastoralism” to fill the existing gap and strengthen the teaching -learning processes. The lecture note is primarily prepared for students pursuing their bachelor of veterinary medicine, doctor of veterinary medicine (DVM) or related professions in various higher teaching institutions. It also helps those graduates who are in service or specializing on the area. To develop this lecture note, materials have been gathered and adapted from different standard books, journals and research reports and adopted to the Ethiopian context. The lecture note has six chapters covering major and relevant topics of the course. Within each chapter, important topics are identified and discussed in simple language so as to facilitate rapid reading and understanding of important concepts. Each chapter has activity question and also followed by review questions that can enable the reader to use them as self-assessment tools. The authors strongly believe that this teaching material will play a crucial role in promoting the teaching-learning process through delivery of pertinent information to the trainees. Nevertheless, constructive comments and suggestions from readers are welcome so as to further strengthen the lecture note.

Bamboo (Melocanna baccifera) plant plays a significant role in traditional Asian medicine and it can be used as an
alternative to various chemo-therapeutics or prophylactic agents used in aquaculture. In the present study, the
1st experiment was done for the preparation of extracts from bamboo leaves by using 90% alcohol as a solvent. In
the 2nd experiment, toxicity study was carried on Labeo rohita fingerlings (average length of 10.3 ± 1.5 cm and
weight 18.5 ± 1.5 g) using BLAL (Bamboo Leaf Alcoholic) extract and it did not show any mortalities in fish
even at the dose of 20 g kg−1 body weight, which can be regarded as virtually non-toxic with minimal effect. The
3rd experiment was conducted to find out the effect of BLAL extract based isocaloric and isonitrogenous feed
(doses: control- 0.0%, diet T1-0.01%, diet T2-0.1%, diet T3-1% BLAL extract kg−1 feed) on the haemato-immuno-
biochemical parameters of L. rohita fingerlings (average length 15.7 ± 1.5 cm and weight 20.2 ± 1.5 g).
Regular sampling was done (on 7th, 15th, 30th and 60th day of feeding) for different haematological, immunological
and biochemical parameters. The study revealed that the best response occurred within 7 days of
feeding with BLAL extract and long-term feeding have shown immunosuppressive condition in the fish. In the 4th
experiment, fish were exposed to multiple stressors like low pH stress, and Saprolegnia parastica infection after
feeding with BLAL extract (0.1%) based feed for 7 days. The study showed that the BLAL extract can make fish
resistant to single stress however, not able to reduce the fish mortality under multiple stresses (S. parastica
infection under low pH). Thus, it can be concluded that the BLAL has the potentiality to be used as a non-toxic
phyto-prophylactic which can induce non-specific immune response, reduces the low pH stress responses and
increases the resistance against saprolegniasis under neutral pH condition in rohu fingerlings.

Earthen pond rearing system is the most prevalent type of aquaculture facilities in Egypt due to low construction costs. Such facilities are characterized by open nature which allows large numbers of imposing factors to interact with cultured fishes during the production cycle. Aquatic invasive species (i.e., red swamp cray fish: Procambrus  clarkii), migratory birds, wild amphibians and reptiles are staggering examples for such interacting factors, which impose severe deleterious impacts on the fish production cycle. The active nature and vast distribution of these species will ultimately violate the rearing regime of the fish farming facility through the establishment, proliferation and spread of pathogens by mechanical, biological and direct infectious routes. Further, the wet nature of aquaculture operations, frequent introduction of new broodstocks, fish meal, reuse of agricultural drainage water and faulty use of animal manure as well as movement of fish from different localities offers a multitude of opportunities for pathogen entry to fish farming operations. Once introduced, pathogens can easily proliferate within the systems leading to potent disease issues, sometimes leading to a complete collapse in production, or more intermittent outbreaks affecting output reliability. Therefore, this study is designated to examine the key role played by invasive species, vectors and reservoirs responsible for pathogen introduction into fish farms. Moreover, the essential needs were discussed for development of practical methods to limit pathogen introduction, spread and proliferation at any level of fish production cycle parallel with the adoption of Good Aquaculture Practice (GAP) and Hazard Analysis and Critical Control Points (HACCP) in Egyptian fish farms.

proved to be second on the race (complete healing was achieved 6 days post treatment with very good grade (+++)). This study demonstrates the clinical value of fish models in establishment of new approach for combating prevalent invasive skin affections in aquaculture.

Aquatic animal diseases are one of the most significant constraints to the development and management of aquaculture worldwide. As a result, measures to combat diseases of fish and shellfish have assumed a high priority in many aquaculture producing countries. RNA interference (RNAi) has emerged as a powerful tool to manipulate gene expression in the laboratory. The discovery of RNA interference in mid ninety's added a new dimension in the regulation of gene expression by different types of RNA. It is a phenomenon in which double-stranded RNA (dsRNA) is the initiating factor in post-transcriptional gene silencing. It is a process in which the introduction of a double-stranded RNA (dsRNA) in the cells causes the specific degradation of an mRNA containing the same sequence. The double-stranded RNA (dsRNA) and short interfering RNA (siRNAs) alone cannot degrade mRNA but require the assistance of two enzymes namely Dicer and RNA-induced silencing complex (RISC). Among its many potential biomedical applications, silencing of viral genes stands out as a promising therapeutic strategy. The specific nature of theinhibition of protein production of cells has resulted in an explosion of research to understand and exploit RNAi. The technique is now established in in vitro systems, and much work is focused on adapting RNAi for in vivo application. The field ofRNA interference (RNAi) is moving at an impressive pace and generating excitingresults. A better understanding of post-transcriptional gene silencing (PTGS) shouldallow a more efficient response to viral infection and the development of transgene/host associations that can override silencing to allow the expression of interested proteins. The potential of the technology in understanding physiological and pathological processes is significant, while its development as a therapeutic agent holds much promise as targeted agents.

El Niño / Oscilación del Sur (ENOS) por interacción oceánico-atmosférica en el océano Pacífico tropical afecta al componente biológico. Estudios científicos sugieren que en iguanas marinas (Amblyrhynchus cristatus Bell, 1825) de Galápagos el impacto es negativo. La Fundación Charles Darwin para obtener información de largo plazo estableció un proyecto permanente de monitoreo en un sector de la isla Santa Cruz. El área de estudio abarca 6.1 km de costa desde Punta Núñez al sureste de la Isla hasta el muelle de la Estación Científica Charles Darwin. Este trabajo analizó el estado de salud de la población de iguanas marinas en esta zona por niveles 0-5 (saludable a muerta), comparando entre los períodos ENOS (1997-98) y Post ENOS (2000-01). Se determinó la diferencia entre éstos, y la relación entre niveles de salud y condiciones ambientales (precipitación, temperatura superficial del mar y del aire). Los resultados mostraron una diferencia significativa (z 0,05 =0.4477; P<0.0001) en el nivel de salud de la población de iguanas marinas entre los dos períodos, pese a que los niveles de salud no presentaron relación directa (r<0.426) con las condiciones ambientales. Sin embargo, si las condiciones ambientales anómalas se mantienen la relación es directa (r=0.624), siendo notorio el deterioro del estado de salud después del sexto mes con temperatura superficial del mar >23°C (promedio Post ENOS), que luego de un periodo igual en condiciones normales se recupera. Palabras Clave: Amblyrhynchus cristatus, efecto de ENOS, estado de salud, temperatura superficial del mar, Galápagos.

Natural variation in the physiological variables of the eastern oyster Crassostrea virginica from a tropical climate have until now been poorly documented. This study was conducted to characterize the influence of hydrological variables (salinity, temperature, nitrate, nitrite, ammonium, soluble reactive phosphorus [SRP], and soluble reactive silica [SRSi]) on oyster physiological variables (total hemocyte cells (THC), reactive oxygen intermediates (ROIs), agglutination, lysozyme, and protein concentration). Oysters were collected during 3 different months (April, August, and December) from seven sites in Terminos Lagoon SW-Mexico. The association of physiological variables with oyster condition index (CI) was also studied. The physiological variability explained by environmental variables was high (30.7%) when compared with the variability explained by the condition index (8.9%). The independent effect of salinity explained 69.7% of the total variability in the physiological variables (F-ratio = 3.4; P = 0.002, Monte Carlo test with 499 permutations). Protein concentration was significantly correlated with spatial salinity variation (r2 = 0.89; H = 27.01, P < 0.0001). Site effects were salinity-protein discriminated (F-ratio = 3.406; P = 0.002). Temperature was not a significant variable in the oyster physiological variability. The oysters from marine freshwater transition zones were less affected in their CI and physiological parameters than oysters from permanent high (>28 psu) or low salinity conditions (<10 psu). This study represents the first step toward integrating specific C. virginica physiological information from tropical areas.

Through collaboration with Inuit hunters, we examined the stomach contents of 142 seals (ringed seals [Phoca hispida; n = 135], bearded seals [Erignathus barbatus; n = 6], and one harbour seal [Phoca vitualina; n = 1]) hunted between 2007 and 2019 from communities around Nunavut to assess whether seals in the eastern Canadian Arctic ingest and retain plastics in their stomachs. The seals in this study ranged from juveniles to adults of up to 30 years of age, and 55% of the seals were males. We found no evidence of plastic ingestion in any of the seals suggesting that seals in Nunavut are not accumulating plastics (>425 μm) in their stomachs. These data provide important baseline information for future plastic pollution monitoring programs in the Arctic.

The testicular cystic structure and the abrupt morphological changes that the fish testis undergoes during the reproductive cycle (RC) make it an interesting model for studying the regulation of spermatogenesis, in particular the role of matrix metalloproteinases (Mmps). The gilthead seabream is a seasonal breeding teleost whose testis undergoes drastic remodeling events, especially during the post-spawning stage when a massive infiltration of a immune cell type, the acidophilic granulocytes, occurred. Bearing this in mind, we studied the gilthead seabream testis gelatinolytic activities involved in migration and tissue remodeling and its regulation by endocrine, immune and tissue stimuli. Thus, we demonstrated that the germinal epithelium of the testis showed gelatinolytic activity during spermatogenesis and post-spawning but not during resting, when only scarce interstitial cells were stained. Moreover, the precursor and mature forms of two gelatinases, Mmp2- and Mmp9-like, were active in the gonad, whose activities were up-regulated by 17beta-estradiol (E(2)) but not by lipopolysaccharide (LPS)/bacterial DNA (VaDNA) in testicular cell suspensions. E(2) and LPS/VaDNA also up-regulated a variety of cytokines and chemokines. We also cloned mmp9, mmp13, tissue inhibitors of Mmps (timp)-2a and timp2b genes and found that all of them were expressed in the gonad in a RC stage-dependent manner. Interestingly, mmps and timps were highly expressed by the testicular acidophilic granulocytes. Moreover, in these cells, the gelatinolytic activity seemed to correspond to the precursor and mature forms of putative Mmp2 and Mmp9 gelatinases, while the main gelatinolytic activity seemed to correspond to the mature form of Mmp2 in head-kidney acidophilic granulocytes. Finally, although none of the stimuli used were able to induce the gelatinolytic activity of Mmp9-like in head-kidney acidophilic granulocytes, the expression of mmp9, timp2a and timp2b were all up-regulated by LPS/VaDNA in these cells, while only mmp9 and timp2a expression increased upon stimulation with gelatin.

proved to be second on the race (complete healing was achieved 6 days post treatment with very good grade (+++)). This study demonstrates the clinical value of fish models in establishment of new approach for combating prevalent invasive skin affections in aquaculture.

The book is a systematic diagnostic guide of most common viral diseases of fish and shellfish. It is recommended for both undergraduate and graduate students of Aquatic Animal Health, Fish & Shellfish Diseases , Aquatic Animal Virology , Clinical Aquatic Virology and Fish / Shellfish Pathology majors. The book is also very useful for aquatic veterinarians , fish pathologists, fisheries scientists and marine biologists.

The testicular cystic structure and the abrupt morphological changes that the fish testis undergoes during the reproductive cycle (RC) make it an interesting model for studying the regulation of spermatogenesis, in particular the role of matrix metalloproteinases (Mmps). The gilthead seabream is a seasonal breeding teleost whose testis undergoes drastic remodeling events, especially during the post-spawning stage when a massive infiltration of a immune cell type, the acidophilic granulocytes, occurred. Bearing this in mind, we studied the gilthead seabream testis gelatinolytic activities involved in migration and tissue remodeling and its regulation by endocrine, immune and tissue stimuli. Thus, we demonstrated that the germinal epithelium of the testis showed gelatinolytic activity during spermatogenesis and post-spawning but not during resting, when only scarce interstitial cells were stained. Moreover, the precursor and mature forms of two gelatinases, Mmp2- and Mmp9-like, were active in the gonad, whose activities were up-regulated by 17beta-estradiol (E(2)) but not by lipopolysaccharide (LPS)/bacterial DNA (VaDNA) in testicular cell suspensions. E(2) and LPS/VaDNA also up-regulated a variety of cytokines and chemokines. We also cloned mmp9, mmp13, tissue inhibitors of Mmps (timp)-2a and timp2b genes and found that all of them were expressed in the gonad in a RC stage-dependent manner. Interestingly, mmps and timps were highly expressed by the testicular acidophilic granulocytes. Moreover, in these cells, the gelatinolytic activity seemed to correspond to the precursor and mature forms of putative Mmp2 and Mmp9 gelatinases, while the main gelatinolytic activity seemed to correspond to the mature form of Mmp2 in head-kidney acidophilic granulocytes. Finally, although none of the stimuli used were able to induce the gelatinolytic activity of Mmp9-like in head-kidney acidophilic granulocytes, the expression of mmp9, timp2a and timp2b were all up-regulated by LPS/VaDNA in these cells, while only mmp9 and timp2a expression increased upon stimulation with gelatin.

The protozoan Perkinsus marinus is considered the most important pathogen of the eastern oyster Crassostrea virginica, causing high mortality in natural and farmed oysters on the Atlantic coast of the US. In Mexico, no serious P. marinus epizootic has been reported. This study describes the current state of P. marinus prevalence in Terminos Lagoon (Mexico) associated with environmental factors including salinity, temperature, ammonium, nitrate, nitrite, silica, and phosphorus. In addition, the association of physiological (hemocyte density, protein concentration) and immunological (lysozyme, agglutination) parameters with the infection were studied. The prevalence was significantly different among seasons with mean values of 70, 23, and 7% in the dry (February to May), rainy (June to September) and north-wind (October to January) seasons, respectively. Only light infection intensity (Mackin scale value <1) was observed. Prevalence of P. marinus was associated with seasonal salinity, phosphorus, and silica variations. Comparisons of oyster health demonstrates that the rainy and north-wind seasons are stressful periods. Redundancy analysis showed that only 34% of the variation in seasonal P. marinus prevalence was explained by protein concentration (21%), lysozyme (12%), and agglutination (1%). Overall, the data suggest that freshwater input associated with high nutrient concentrations during the rainy and north-wind seasons has a strong negative effect on P. marinus prevalence and also influences the oysters' physiology. It is probable that this seasonal stress was responsible for the absence of an epizootic event in Terminos Lagoon.