Cyprinodontiformes vivíparos e ovovivíparos
Artigos - Resultado da prospecção ao lago em Fevereiro de 2009
Articles - The February 2009 fish pond assessment
The February 2009 fish pond assessment
Miguel Andrade - published at this website in May 2009
The abstract of this article is clear enough - “
reintroduction projects may fail because captive-reared animals do not
possess the behavioural skills required for survival in the wild.
Most of common garden fish ponds are unquestionably bigger than any indoors tank and, off course, can contain larger water storage capacity and room by that reason.
Besides space, a aforementioned excellent argument, there are also a few other excellent points of view to take in consideration, like the benefits of sun light, ecological conditions as well as... all we need, to recreate, at our own home, any natural habitat, better than in whichever other confinement setup.
Figure 1 - This picture shows the fishpond one day before the intervention ( February 22nd 2009 ).
For climacterically reasons, sometimes our
local weather conditions are quite far from the original, with reference
to most species. As a rule for alien ( exotic ) fish species, standing
outdoors for longer than certain precise periods of the year can
represent a risk, either due to high temperatures during the hot peeks
or, most commonly and frequently, by cold narcosis during winter colder
When we carefully study the potential of or local climate with the intention of preserving exotic species captive populations in outdoors environments, it’s necessary to take into account that the weather is a very unpredictable and dynamic reality.
Climate cycles and anomalies should ever be considered as well.
This is more significant when you don’t want to cause innocent lives lost or suffering to fish.
I confess that my experience with these species in semi-natural environment all year round is recent and my knowledge about this issue is still short and modest, but the intention to avoid predictable lost of fish by cold was always present.
The first group left outdoors in permanence had begun only in October 2005; therefore due to some unusual weather irregularities during this period of time, the issue on climate anomaly on this acknowledgment is so important.
That’s why the late fishpond assessment procedure, completed last February 2009 and described further, was imperative in face of the atypical frosty conditions that took place in the beginning of January 2009.
Another climate anomaly is presently taking place, not only for the warm end of this winter season but as well as for the drought circumstances in March.
We had 202,3 mm of rain fall in January, but only 75,9 mm in February and, some hard to believe, no more than 5,6 mm in March, with remarkable effects in maximum daily temperatures increasing due to the lack of clouds and the fresh breezes that come with the expected seasonal rainfall.
« March monthly accumulated precipitation in the central and western regions of the Iberian Peninsula presents a clear continuous decline of 50% during the 1960–97 period.
However, this is merely the most visible aspect of a larger phenomenon over the North Atlantic/European sector. The European precipitation trends in March for the period 1960–2000 show a clear distribution of increasing precipitation in the northern regions ( the British Isles and parts of Scandinavia ) together with decreasing trends throughout the western Mediterranean Basin », ( Paredes et al. 2006 ).
« The widespread declines of March precipitation in Iberia, and the consistent negative precipitation trends, predicted by most climate change scenarios, increase the concern about a possible future scenario with scarce water resources.
It is within this context that the detected decrease of precipitation in March can be indicative of “ things to come ”, that is, lack of precipitation and water when it is most needed for spring plant growth as well as for human consumption during spring and summer seasons », ( Pereira et al. 2002 apud Paredes et al. 2006 ).
« If the average of March precipitation is kept within the present range of values and summer droughts become the norm, it is not difficult to foresee increasing water resources problems, including those of a transnational nature between Portugal and Spain », ( Vlachos and Correia 1999 apud Paredes et al. 2006 ).
Occasional abnormal conditions are not definitely substance for a climate change classification, but the prevalence of unusual tendencies in long-term, may be regarded as a significant change in the expected patterns of average weather of a specific region.
The climate change terminology reflects abnormal variations to the expected regional climate, according to the available data about a particular region precedent.
On the January 29th, 2006, something extraordinary took place when we had a snowfall event in areas where typically it is very improbable that could happen.
The intensity of this rare phenomenon wasn’t severe on this particular occasion, and most of the snow traces soon disappeared in a matter of minutes or hours. The last time it had happen previously in Lisbon it was in 1954.
On the January 28th 2007, some snowfall in several unusual regions had surprise again for the rarity of the phenomena, although it was the 2nd consecutive winter.
2007 was also another drought example on the recent years.
The total amount of rainfall was so glaringly small, that it was considered the second driest year since 1931.
Nonetheless, the standard draw season that take place in summer it was characterized for high quantities of precipitation, a situation completely out of the expected patterns of rainfall.
For this reason, the temperatures in June, July and August were lower than the usual, so the summer of 2007 was the coldest in no less than two decades.
The year 2008 was characterized by average values of maximum temperature, average temperature and minimum temperature slightly below the average of the 1971-2000 reference period, in - 0.1ºC ( -0.18ºF ), - 0.4°C ( -0.72ºF ) and - 0.2°C ( -0.36ºF ) respectively.
Also the figures of precipitation were below the average for the 1971-2000 reference periods, described as very dry to dry.
Thus, 2008 was the 8th driest year since the start of records in 1931, but on this same period the year 2005 was the driest.
The year 2008 ended with dry weather.
November 2008 was characterized by unpleasantly cold air temperatures. The value of the average minimum temperature, 4.7ºC ( 40.4ºF ), it was the third lowest value since 1931, with an abnormality of – 3.2ºC ( -5.7ºF ) below the 1971-2000 reference. The previous lowest values were 4.3ºC ( 39.7ºF ) in 1956 and 4,6ºC ( 40.2ºF ) in 1971.
December 2008, was characterized by average values of air temperature below the normal values for the 1971-2000 reference, and the average and maximum average temperature of the air less than 1.4ºC ( 2.5ºF ) compared to their average values and the average minimum temperature of less than 1.7ºC ( 3ºF ).
In some stations the number of days in which the minimum air temperature was below 0°C ( 32ºF ) was more than 15 days, as example Mirada do Douro with 19 days, Sabugal with 18 days and Mirandela, Macedo de Cavaleiros and Carrazeda de Ansiães with 16 days.
The values of precipitation were under the average figures for 1971-2000 reference, described as dry as the standard for December, which contributes to the persistence of the status of dry situation across the country, with 68% of the territory in dry lower level, 31% in moderate drought and 1% in severe drought, ( Instituto de Meteorologia – http://www.meteo.pt/en/index.html ).
On January, 2009, besides moderate snowfall were it was typically expected, but again in some unexpected region as well.
A severe icy week has carried another big surprise for people, with snow accumulation in an important part of Portugal’s Northern and Central regions as well as for the high altitudes.
The country was barely prepared to deal with such a frozen shock. In some areas a few small villages were in fact isolated by snow, disrupting public infrastructures and services for a few days, until it was melted or sublimated.
The official version concerning the above mentioned extend of snow besides the classic regions was that “ the [ atypical ] snowfall occurred in the central and southern regions of mainland Portugal was caused by a low-pressure centre passing along territory, from north to south. The low had formed in a very cold air mass, and an instability line was associated with it.
The air mass was gradually transported in the circulation of an anticyclone located over the British Islands, from Central Europe to the Biscay Gulf and later southwards to the Iberian Peninsula.
During the snowfall, the minimum air temperature reached values as low as 0.5ºC ( 32.9ºF ) at Figueira da Foz ( 10:10 ), 0.4ºC ( 32.7ºF ) at Rio Maior ( 12:50 ), 0.1ºC ( 32.1ºF ) at Santarém ( 13:30 ), 0.4ºC ( 32.7ºF ) at Torres Vedras ( 14:50 ), 0.5ºC ( 32.9ºF ) at Lisbon ( 15:00 ) and 0.8ºC ( 33.4ºF ) at Setúbal ( 16:10 ) “, ( Instituto de Meteorologia – http://www.meteo.pt/en/index.html ).
Note that all the above mentioned locations are located out of the small number of expected regions of traditional snowfall or snow-prone areas.
Another interesting conclusion was that the cold air mass was downward from North to South at the expected warmer period of the day.
In February 2009, Serra da Estrela, that is the highest mountain system in our territory and includes mainland Portugal's highest point, had to cope with an 8 meters depth layer of snow, something that was not experienced for many decades.
But February 2009, in terms of precipitation, was classified as normal to dry.
The average amount of precipitation was again below the average once more.
By that reason, the average maximum temperature was slightly higher than the standard value for the 1971-2000 reference periods, with an abnormality of +0.4°C ( 0.7ºF ).
Nevertheless, the values of average temperature and average minimum air were below the reference, with values of -1.3ºC ( -2.3ºF ) and -0.4°C ( -0.7ºF ) respectively, ( Instituto de Meteorologia – http://www.meteo.pt/en/index.html ).
However, despite the extremely cold isolated events during last winter, in particular between November 2008 and January 2009, there is a general tendency for a universal average temperature increase.
So far, since the temperature records have began, 1997 it was the warmest year of all.
On the top 10 warm years, 7 took place after 1990 ( 1990, 1995, 1996, 1997, 1998, 2003 and 2006 ).
The summer of 2006 it was the 5th warmest since 1931, just fallowing after 1949, 2003, 2004 and 2005.
I am not conjecturing about the global warming theory, but only pointing that we can in fact be in presence of changing patterns of rainfall, snowfall, and drought.
There are at least evident changes on the climate cycle and on the seasonal distribution of these events with prevalence of a few surprisingly abnormal conditions.
Another evident tendency is the occurring rate of changes in climate, which is now greater than that experienced in the past.
This changing evolution is now expected to accelerate further in the coming decades.
After the coldest November 2008 ever
since on my personal records, a number of cooling days in a December
2008 with particularly low maximum daily temperatures but, above all, an
exceptionally frosty period in the beginning of January 2009, some of
the less cold tolerant species outdoors were this winter under a severe
Carassius auratus ( aquarium strain - Shubunkin )
Cyprinus carpio x Cyprinus rubrofiscus ( Koy )
Cyprinodon alvarezi ( El Potosi )
Heterandria formosa ( aquarium strain )
Oryzias latipes ( aquarium strain )
Skiffia multipunctata ( Lago de Camecuaro )
Xenotoca eiseni ( aquarium strain )
Ameca splendens ( aquarium strain )
Aphanius mento ( Elbistan )
Fundulus cingulatus ( aquarium strain )
Figure 2 - Xenotoca eiseni, one of the most interesting surprises.
These fish are
surprisingly cold tolerant species.
J.L. Kelley, A.E. Magurran and C. Macý´as-Garcia, 2005. The influence of rearing experience on the behavior of an endangered Mexican fish, Skiffia multipunctata, Biological Conservation 122 (2005), pp. 223–230.
Paredes, D., Trigo, Ricardo M., Garcia-Herrera, Ricardo and Trigo, Isabel Franco, 2006. Understanding Precipitation Changes in Iberia in Early Spring: Weather Typing and Storm-Tracking Approaches. Journal of Hydrometeorology, Volume 7, Meteorological Society, February 2006, pp. 101 – 113.
Pereira, J., and Coauthors, 2002. Forests and biodiversity. Climate Change in Portugal: Scenarios, Impacts and Adaptation Measures — SIAM, F. D. Santos, K. Forbes, and R. Moita, Eds., Gradiva, 363–414.
Vlachos, E., and F. N. Correia, 1999. Shared Water Systems and Transboundary Issues: With Special Emphasis on the Iberian Peninsula. Luso-American Foundation, 454 pp.
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