Eutrophication patterns in an eastern Mediterranean coastal lagoon: Vassova, Delta Nestos, Macedonia, Greece

The results of an intensive monitoring study of main eutrophication parameters in relation to fish farming management, climate and hydrography in the Vassova coastal lagoon (Nestos Delta) are presented. The overall aim is to produce basic knowledge in order to contribute to the management of eutrophication of coastal lagoons at local and national levels. Due to extensive spatiotemporal variability of the measured parameters correlation and regression polynomial analysis was used to identify patterns (p<0.05). Freshwater was the main source of nitrate and phosphate in the lagoon. This finding has justified the reduction of freshwater inflow in the past, which, however, has increased mean salinity to 30 PSU and reduced spatial salinity gradients. Maximum nitrate values in winter coincided with adverse climatic and hydrographic conditions (high precipitation, strong NE to E winds and low tide) and fish farming management that hinder water circulation. Dissolved phosphorus variability indicated the combination of the external (freshwaters) and internal (sediment) P-sources. N/P water values indicated nitrogen being the most important nutrient for primary producers throughout the year, except in winter, when phosphorus was the most important nutrient. Practical measures for improving fish farming practices to decrease “eutrophication risk” during winter are suggested. Existing nutrient data from the Vassova and from other Greek lagoons in comparison were also presented and discussed

Incidence of an intense Caligus minimus Otto 1821, C-pageti Russel, 1925, C-mugilis Brian, 1935 and C-apodus Brian, 1924 infection in lagoon cultured sea bass (Dicentrarchus labrax L.) in Greece

An unusual case reported for the first time. of enhanced pathology, of two Caligidae species infecting a new host Dicentrarchus labrax reared in Eratino lagoon (North Greece). During winter months (December-February 1998-1999), moribund fish were observed in the lagoon: fish showed slow swimming at the surface of the water, were lethargic and cacchectic. Infected fish had either pinpoint or dispersed ulcerative skin lesions on the head and around and inside the buccal area as well as hemorrhages. Four Caligidae species were found namely: Caligus minimus, C. pageti. C mugilis and C. apodus as well as one gill trematode parasite. The prevalence and intensity of C minimus was high throughout the year with a distinct peak of intensity in winter. (C) 2004 Elsevier B.V. All rights reserved

Parasites of Mugilidae spp reared under semi-intensive and intensive conditions in Greece

Parasites are described from five Mugilidae species (Chelon labrosus, Liza aurata, L. raulada, L. saliens and Mugil cephalus) reared in a lagoon and of M. cephalus reared under intensive conditions (open ponds and recirculating freshwater systems) in Greece. Mugilids reared in lagoons were infected with a variety of parasites but these did not cause problems and mortality. Some of these species (Bouedenia monticelli, Lingophorus spp., Dicrogaster contractus, Haploporus benedeni, Lecithaster confusus, Lecithobotrys putrescen, Saccocoelium obesum, S. tensum) are reported for the first time in the region as well as in the country. Ergenstrema mugilis is reported for the second time in C. labrosus. Mugil cephalus was tolerant, in general, to diseases under intensive rearing and the main problem observed was recurrent but intensive infections by Chilodonclla sp. and Microcotyle mugilis reported for the first time in this host. Mortality of the fish in freshwater reached 5% during summer months and was higher (20%) during long-term salt treatment. Microcotyle mugilis has not been reported before in this host and the mortality was attributed mainly to this parasite

Prevalence and pathology of ectoparasites of Mediterranean sea bream and sea bass reared under different environmental and aquaculture conditions

Sea bream, Sparus aurata L., and sea bass, Dicentrarchus labrax L., were sampled from an off- shore cage farm in eastern Greece, an inshore cage fish farm in southern Greece, and a lagoon in northern Greece. The prevalence and intensity of Metazoan parasites and factors associated with the prevalence were investigated. In Farm 1 (eastern Greece), ectoparasite prevalence in sea bream and sea bass was 61.5% and 76.9% for Monogenea, none for Isopoda, and 0 and 23% for Copepoda. In Farm 2 the prevalence was 13.3% and 26.3% for Monogenea, 13.7% and 20% for Isopoda, and 0 and 13.6% for Copepoda. In the lagoon, the prevalence of ectoparasites was 100% and 21.9% for Monogenea and Copepoda, respectively. The lagoon had the highest prevalence of parasites among the studied ecosystems, however, the variety did not significant- ly affect the health of the infected fish. In Sparidae, gill lesions were due to monogeneans while skin and eye lesions were due to larvae of the isopod Ceratothoa oestroides that caused severe pathology. Furnestinia echeneis and Diplectanum aequans were host specific to sea bream and sea bass, respectively, and persisted in all aquaculture systems. Lernanthropus kroyeri was host specific and detected only in sea bass from the cage farms

Efficacy and toxicity of orally administered anticoccidial drugs for innovative treatments of Polysporoplasma sparis (Sitja-Bobadilla and Alvarez-Pellitero 1985) infection in Sparus aurata L

The purpose of this study was to test experimentally different drugs and therapeutic schemes in order to find a efficient commercial treatment for fish infected with myxosporeans. Two series of land-based experiments and one experimental cage trial were performed for this purpose. In the first land-based experiment, 10 and 30 g Sparus aurata naturally infected in the kidneys with Polysporoplasma sparis were used. Initially, six different doses of Fumagillin, two doses of Toltrazuril, and one dose of Amprolium, ESB3 and Salinomycin were tested. In the second land-based experiment, 25 and 50 g fish infected with the same parasite were treated with Origanum essential oils, Toltrazuril with propylene glycol, Amprolium, and a combination of Salinomycin 12% + Amprolium (SA). In the field trials, 15 and 155 g S. aurata infected with the same parasite were treated with SA, Origanum essential oils and Fumagillin. In all trials the drugs were incorporated in food and administered according to the selected schemes, while their efficacy was evaluated in terms of mortality (acceptable level <2%), pathology and prevalence rate of P. sparis. According to our results the SA combination proved to be the most effective treatment against P. sparis infection in S. aurata: (i) the therapeutic scheme and commercial product used was not toxic and (ii) a significant reduction in percentage of prevalence was observed

Efficacy and toxicity of orally administrated anti-coccidial drugs for innovative treatments of Myxobolus sp infection in Puntazzo puntazzo

This study tested drugs and therapeutic compounds to determine effective commercial treatment for fishes infected with myxosporeans. Two series of shore-based experiments and 1 field trial were performed. For the shore-based experiments we used Puntazzo puntazzo (ca. 20 g weight) with kidneys infected with Myxobolus sp. Initially, 6 different doses of Fumagillin, 2 doses of Toltrazuril, and 1 dose of Amprolium, ESB3 and Salinomycin were tested. In the second shore-based experiment, infected fish were treated with Origanum essential oils, Toltrazuril with propylene glycol, Amprolium, and a combination of Salinomycin 12% + Amprolium. (SA). In the field trial, P. puntazzo (ca. 165 g) infected with the parasite were treated with SA, Origanum essential oils and Fumagillin. In all trials, the drugs were added to the feed and administered according to the selected regimen. Their efficacy was evaluated in terms of mortality (acceptable level was 6 mg kg(-1) body wt for 6 wk in the interstitial renal tissue, where slight inflammation arose. The highest dose tested (25 mg kg(-1)) also produced necrosis in the interstitial tissue, degeneration of the epithelial cells of the tubules and a reduction in melanomacrophage centre numbers. The SA combination proved the most effective treatment for Myxobolus sp. infection of P. puntazzo as (1) the therapeutic regimen and commercial product was not toxic and (2) a significant reduction occurred in the prevalence rate

Report of Sparicotyle (Microcotyle) chrysophrii Van Beneden and Hesse 1863, Atrispinum seminalis Euzet and Maillard 1973 and Polylabris tubicirrus Paperna and Kohn 1964 (Monogenea) on captive sea bream (Sparus aurata) and sharp snout sea bream (Diplodus puntazzo) in coastal Greece and Italy

During the years 2000-2003, caged gilthead sea bream (Sparus aurata L.) and sharp snout sea bream (Diplodus puntazzo C.) from two farms in Greece and two farms in Italy (the Central Thyrrenian Sea) were examined. Sparus aurata from Greece was moderately infected with Furnestinia echeneis and Sparicotyle chrysophrii. Diplodus puntazzo from the Greek farms were infected with three polyopisthocotylean monogeneans: Atrispinum salpae, A. seminalis and S. chrysophrii. In Italy, on the gills of cultivated S. aurata, a polyopisthocotylean parasite was identified as Polylabris tubicirrus which is considered host specific and only affecting breams of the genus Diplodus. Furthermore, D. puntazzo and S. aurata showed the transfer of the monogenean S. chrysophrii from S. aurata (its type host) to D. puntazzo which is never found infected in wild conditions by this parasite. The presence of these parasites, and in particular S. chrysophrii in cultured D. puntazzo, is an important finding for aquaculturists in terms of potential disease problems