Effects of Loma morhua (Microsporidia) infection on the cardiorespiratory performance of Atlantic cod Gadus morhua (L).

Abstract

The microsporidian Loma morhua infects Atlantic cod (Gadus morhua) in the wild and in culture and results in the formation of xenomas within the gill filaments, heart and spleen. Given the importance of the two former organs to metabolic capacity and thermal tolerance, the cardiorespiratory performance of cod with a naturally acquired infection of Loma was measured during an acute temperature increase (2°C h À1) from 10°C to the fish's critical thermal maximum (CT Max ). In addition, oxygen consumption and swimming performance were measured during two successive critical swimming speed (U crit ) tests at 10°C. While Loma infection had a negative impact on cod cardiac function at warm temperatures, and on metabolic capacity in both the CT Max and U crit tests (i.e. a reduction of 30-40%), it appears that the Atlantic cod can largely compensate for these Loma-induced cardiorespiratory limitations. For example, (i) CT Max (21.0 AE 0.3°C) and U crit (~1.75 BL s À1) were very comparable to those reported in previous studies using uninfected fish from the same founder population; and (ii) our data suggest that tissue oxygen extraction, and potentially the capacity for anaerobic metabolism, is enhanced in fish infected with this microsporidian.

Thermal biology and swimming performance of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus)

“…These data support the findings of previous studies on Atlantic cod (e.g. Gollock et al, 2006 vs. Petersen & Gamperl, 2010, and Powell & Gamperl, 2016 show that AS T is within 10–20% of AS S ), and suggest that the physiological mechanisms responsible for increasing oxygen uptake to meet rising demands are similar during warming and physical activity in this species. The 12 °C-acclimated haddock, on the other hand, had a significantly lower RMR and MMR in the swimming experiment compared to the CT max experiment, but maintained the same AS.…”

A follow‐up study of selected biomarkers of health in cod Gadus morhua L. collected from the southern Baltic off the Polish coast

“…Gonadal impairment due to Microsporidia in roach Rutilus rutilus from the Baltic has been reported previously (Wiklund, Lounasheimo, Lom, & Bylund, ). Systemic xenomas of Ichthyophonus hoferi (Plehn & Mulsow) a microsporidian classified previously as fungal cysts (Reimer & Walter, ) and Loma morhua (Powell & Gamperl, ) have been reported from cod. Interestingly, Möller () reported a low CF (0.742) in a single cod with systemic microsporidiasis as compared to non‐infected cod, which agrees with our finding of a lower CF in fish with Microsporidiosis in the 2015 cod.…”

Integrative Approach for the Reliable Detection and Specific Identification of the Microsporidium Loma morhua in Atlantic Cod (Gadus morhua)

“…Determining xenoma intensity and distribution in host tissues other than gills has been largely neglected, in spite of xenomas from Loma species being known to occur disseminated throughout host tissues (Docker et al. ; Hauck ; Morrison ; Powell and Gamperl ; Rodriguez‐Tovar et al. ; Shaw et al.…”

“…Understanding the temporal and spatial distribution of microsporidian infections will prove critical as aquaculture diversifies to include alternate finfish species that will likely harbor lesser-known microsporidia. Determining xenoma intensity and distribution in host tissues other than gills has been largely neglected, in spite of xenomas from Loma species being known to occur disseminated throughout host tissues Hauck 1984;Morrison 1983;Powell and Gamperl 2015;Rodriguez-Tovar et al 2003;Shaw et al 1998). There is clear indication that Loma species have a tropism for gill endothelial and pillar cells (Hauck 1984;Kent and Dawe 1994;Kent et al 1989Kent et al , 1995Magor 1986;Speare et al 1989Speare et al , 1998.…”