A little bit of salt and heat... a good recipe for goby metabolism?by Maxime Deau, Quentin Garreau and Dorian Raoux
Published by the June 1, 2020 on 2:18 PM
As the literature shows, a variety of factors influence the well-being of fish populations. For example, we know that some fish may or may not be very sensitive to changes in the conditions of their living environment (water temperature or salinity). These changes can affect their metabolism (reduced fertility, growth, etc.) or even, in the worst case, lead to the death of individuals. The goby (Pomatoschistusmicrops) (Figure 1), a relatively tolerant species and an essential central link in the food web is one of the species studied in the observation of the impact of these changes on the fish fauna in the Minho estuary in Portugal (Figure 2).
In this study, the researchers were able to model the evolutionary dynamics of p.microps populations based on models that take into account different parameters of goby's life cycle like fertility, mortality, migration rate and the effect of environmental parameters such as salinity and temperature. The aim of these models is to describe the evolution of the different life stages of this fish by establishing the possible impacts of climate change on their metabolism. In this framework, they studied both the impacts of temperature and salinity and combined the impact of both.
It has been noted that salinity directly influences the metabolism of individuals. Indeed, it plays a particular role in the survival of many aquatic organisms but also on their growth (strong allocation of energy to osmoregulation; Rigal, F. and al.,2008). Therefore, it plays a role in the growth of the goby as well as indirectly on its prey. The latter will be less available, which implies a higher energy expenditure for predation. However, this species resists large variations in salinity (0 to 51 psu). For temperatures, the impact is more diverse. Since the goby does not thermoregulate, its metabolism is directly influenced by the temperature of the environment. In addition to its significant effect on pregnancy, it also has an impact on migration, reproduction, recruitment and mortality. (Sogard, 1997; Hurst et al., 2000; Hales and Able,2001; Hurst, 2007; Jones and Miller, 1966; Claridge et al.,1985; Wiederholm, 1987).
Regarding the goby’s responses to these parameters, the research team has implemented them in the model, running different scenarios (salinity and temperature variations). Temperature and salinity variations studied separately led to population crash, except for a salinity lower than the current state ( -5psu). However, the combination of the two variables gave scenarios showing an increase in the population when the salinity was -5 psu, with temperatures ranging from +1 to +3°C, with an optimum at +2°C (see figure 5).
For example, in extreme temperatures, the fish activity will be greatly reduced, which will imply a decrease in the search for preys or sexual partners, causing feeding and mating problems (predation of eggs by males (Magnhagen, 1992). However, a slight increase in temperature could cause a longer reproduction period, allowing for a greater number of offspring to be generated. It has also been noted that with an increase in temperature, there is a delay in the breeding period, leading to the appearance of offspring in a period that may be less favorable for their proper development (early winter/lower metabolism).
In conclusion, climate change, through its effects on water temperature and salinity, will have a significant impact on common goby populations. Indeed, these parameters have a great influence on the metabolism of these fish (whatever their stage of development).In many scenarios, increases in temperature and salinity can cause crash populations. But beware, in some cases (increase in temperature and decrease in salinity) the population of Pomatoschistus microps would tend to increase. Even if this scenario seems favorable for this species, some others will suffer. in fact, a study conducted on Arctic fish species has confirmed these trends
It is therefore clear that climate change affects population dynamics by changing fish environment and impacting their metabolism. It’s therefore important to continue this kind of study to have a better idea of these repercussion on a global scale. We are largely responsible for climate change, so it is up to us to make sure that we limit our impacts. Here is a link that will teach you how to reduce your carbon footprint through 20 examples of simple everyday actions: http://www.globalstewards.org/reduce-carbon-footprint.htm
Other cited studies:
Claridge, P.N., Hardisty,M.W., Potter, I.C., Williams, C.V., 1985. Abundance, life history and ligulosis in the Gobies (Teleostei) of the inner Severn Estuary. J.Mar. Biol. Assoc. U. K. 65, 951–968.
Hales, L.S., Able, K.W., 2001.Winter mortality, growth, and behavior of young-of-the-year of four coastal fishes in New Jersey (USA) waters. Mar. Biol. 139, 45–54.
Hurst, T., 2007. Causes and consequences of winter mortality in fishes. J. Fish Biol. 71, 315–345.
Hurst, T.P., Schultz, E.T., Conover, D.O., 2000. Seasonal energy dynamics of young of the year Hudson River striped bass. Trans. Am. Fish. Soc. Taylor & Francis 129, 145–157.
Jones, D., Miller, P.J., 1966. Seasonal migrations of the common Goby, Pomatoschistus microps (Kroyer), in Morecambe Bay and elsewhere. Hydrobiologia 27, 515–528.
Magnhagen, C., 1992. Alternative reproductive behaviour in the common goby, Pomatoschistus microps: an ontogenetic gradient? Anim. Behav. 44, 182–184.
Rigal, F., Chevalier, T., Lorin-Nebel, C., Charmantier, G., Tomasini, J.-A., Aujoulat, F., Berrebi, P., 2008. Osmoregulation as a potential factor for the differential distribution of two cryptic gobiid species, Pomatoschistus microps and P. marmoratus in French Mediterranean lagoons. Sci. Mar. 72, 469–476.
Sogard, S.M., 1997. Size-selective mortality in the juvenile stage of teleost fishes: a review. Bull. Mar. Sci. 60, 1129–1157.
Wiederholm, A.-M., 1987. Distribution of Pomatoschistus minutus and P. microps (Gobiidae, Pisces) in the Bothnian Sea: importance of salinity and temperature.Memoranda Societatis pro fauna et flora Fennica 63, 56–62.
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