Low-temperature challenges to gilthead sea bream culture: review of cold-induced alterations and ‘Winter Syndrome’

Abstract

Although gilthead sea bream have been cultured successfully for the last two decades they are particularly sensitive to low temperature. Especially in the northern Mediterranean area, cold affects fish health and decreases fish-farm production, and may even cause mortality through what is known as 'Winter Disease' or 'Winter Syndrome'. This paper reviews the diagnosis and physiological effects of this disease, focusing on recent studies of cold-induced alterations in gilthead sea bream physiology. 'Winter Syndrome' is characterised by multi-organ dysfunction entailing hyposensitivity, erratic swimming, pale and friable livers, necrotic muscles, atrophy of the exocrine pancreas, and distended digestive tract. Its complex aetiology involves several factors such as thermal stress, metabolic depression, immune suppression, and occasional opportunistic pathogens. Low temperatures may be the initial cause of all these factors, except pathogen action. Indoor studies have demonstrated that a drop in temperature causes cold-induced fasting, thermal stress and metabolic depression. These immediate effects are related to an ionic imbalance caused by malfunctions of the gills and digestive system. They are also related to a fatty liver, which appeared steatotic and affected hepatic metabolism and blood composition. The result is a lower immune capacity and fish that are more susceptible to infection. There is no significant thermal compensation under cold conditions and in this situation any additional stress factors can cause fish to suffer metabolic collapse. This study reviews the physiological and zootechnical origins of the disease and, where possible, recommends ways of improving culture conditions during pre-cold, cold and recovery periods.

Resiliency of juvenile walleye pollock to projected levels of ocean acidification

“…It has been hypothesized that ocean acidification may restrict the 'thermal window' of fishes by reducing physiological performance at both high and low temperatures (Pörtner 2010). Low temperatures are known to reduce the effectiveness of ion balance at both the cellular and organismal level and depress feeding ability (Ibarz et al 2010). The degree to which low temperature responses interact with, or exacerbate the effects of, other physiochemical stressors is largely unknown (Hurst 2007).…”

Yearly growth and metabolic changes in earthen pond-cultured meagre <em>Argyrosomus regius</em>

“…Seasonal changes in those abiotic factors affect and modulate the physiological responses, which force fish to vary osmoregulatory, metabolic and growth rates for efficient environmental adaptation (Boeuf andPayan 2001, Vargas-Chacoff et al 2009a). Low water temperatures could induce fasting in cultured species, modifying their metabolic status and triggering an allostatic overload (Polakof et al 2006, Estévez et al 2011, as occurs in the gilthead seabream (Sparus aurata) (Ibarz et al 2010). On the other hand, short but intensive rainfall in autumn/winter (usual in southwestern Spain) can decrease water salinity in earthen ponds, inducing osmotic and consequently metabolic challenges in cultured fish (Vargas-Chacoff et al 2009a).…”

Pathological Investigations of Winter-like Disease in Cultured Sea Breams (Sparus aurata)

“…The controversial etiology of WD is still unknown because there is no correlation between the disease and any specific etiological agent 5,6,8 . However, in previous studies, some bacterial agents such as Aeromonas hydrophila, , and Pseudomonas anguilliseptica [11][12][13] , have been isolated and some parasites such as Sanguinicolid trematodes 14 have been reported during the outbreaks of WD.…”

“…It has been reported that WD outbreaks are appeared during the winter seasons and several environmental stress factors such as decrease in salinity and temperature (<13ºC) of sea water influenced the formation of WD 5,8,10,13 . Hepatic steatosis is accentuated in sea bream affected by WD and a polifactorial, metabolic-based pathology which causes high mortality when the water temperature drops below 11-13ºC 2,4 .…”

“… İletişim (Correspondence)  +90 248 2132173  aaydogan@mehmetakif.edu.tr lower water temperature may be initial reason of all these factors 4,5,7,8 . The purpose of this study was to investigate pathologic changes of an outbreak of winter-like disease affecting cultured sea breams in Turkey.…”