The moth and the climate The effects of climate change on Lepidoptera species in s’Albufera de Mallorca
Author: Jos Abma Date: 05-12-2008 Study: Master Biology, Wageningen University Course code: ENT-70424 Alterra supervisor: Jeroen Veraart TAIB supervisor: Nick Riddiford Wageningen University supervisor: Peter de Jong Examinator: Marcel Dicke
2 Contents
Contents ...... 3 Preface...... 4 1. Literature study ...... 6 1.1 Climate change...... 7 1.2 Moths...... 8 1.3 S’Albufera...... 10 2. Materials and methods ...... 12 2.1 Materials ...... 12 2.1.2 Moth catching...... 12 2.1.2 Meteorological data ...... 14 2.1.3 Digitalisation...... 15 2.2 Analysis ...... 15 2.2.1 Data exploration...... 15 2.2.2 Correlations ...... 15 3. Results ...... 18 3.1 Data exploration ...... 18 3.1.1 Meteorological data ...... 18 3.1.2 Species data...... 22 3.2 Correlations & Regressions...... 26 4. Discussion...... 31 4.1 Data...... 31 4.2 Regressions ...... 31 4.3 Further discussion...... 32 5. Concluding remarks...... 34 Appendix 1 – Tables ...... 36 Appendix 2 – Species focal species ...... 38 Utetheisa pulchella...... 38 Leucania joannisi ...... 39 Other species...... 40 Literature...... 44
3 Preface
This internship report was written as part of my 24-ECTS internship at Alterra. I did this internship as part of my Master Biology on the Wageningen University. I considered this particular internship the perfect opportunity to try and blend both practical fieldwork and going abroad, while also being part of a Dutch system at the same time. Prior to this internship, I have done a thesis on the topic of greenhouse gas emissions from Dutch fen meadows. Doing research in the first of climate change is therefore a follow up on the previous topic. The main difference is here that the main focus is an ecological species group rather than a chemical compound. I aimed for this specifically, since I feel that above all I am a biologist and an ecologist.
In the report, I will focus on the explanation of the scientific research that I have done. The personal learning goals and activities on Mallorca are described in my dairy (Dutch) and reflection report (English). The personal aim for this report has specifically been to improve my scientific writing, in addition to getting my research written.
There are a number of people who have helped a great deal with getting this research to the end. First of all Jeroen Veraart as my primary supervisor at Alterra and Peter de Jong as my University supervisor. Secondly, Nick Riddiford as my supervisor at Mallorca and TAIB. Thirdly, I would like to thank Guus Venderbosch for helping me with understanding Access and modifying the database for my research. Also, I would like to thank the TAIB volunteers and s’Albufera staff who helped me during my time on Mallorca.
I have had a great experience doing this research and I hope you enjoy reading this.
Regards, Jos Abma 05-12-2008
4 5 1. Literature study
Ecology is the study of relations. On earth, the whole ecosystem is a network of relations of species to species. These relations mean that changes in one aspect can lead to changes in one or many others. The study of ecosystems can therefore help us understand the world around us. Humans are and have been an important influence on the natural world. This has lead to an increasing change in the worlds ecosystems due to human influence. At the same time, the knowledge of humanity’s influence on the natural world has lead to an interest in preserving the worlds ecosystem. In order to preserve species and ecosystems, knowledge is required to ensure maximum effectiveness of management plans. The main background of this internship was formed by the continuous data gathering done in the s’Albufera parc natural on Mallorca. Since 1991, moth data has been collected on a regular basis by TAIB (The Albufera Initiative for Biodiversity). The main goal for this collection is to get a clear overview of the moth population in s’Albufera de Mallorca. A meteorological station has been operational at s’Albufera since 1986, providing continuous measurements. These measurements have never been used together to look at the connection between the meteorological data and the moth data. This research will mainly focus on answering the question whether there is a connection between the meteorological data and the moth data. Changes in the temperatures of the island will also be used as a measure for climate change. The results of the research will therefore also link the dynamics of the moth population to the meteorological data. In addition, this research will concern itself with the absolute changes in the moth population, irrespectively of any causal effects. Moths are members of an order called the Lepidoptera . Literally this means ‘scaled’ (Lepi) ‘wings’ (doptera). They are a very well studied group, especially the superfamily of the Papilionoidea (butterflies). This knowledge comes forth from the popularity butterflies, moth and skippers have enjoyed with the naturalists of the past. In addition, many moths are pests on cultural crops, such as cotton. Knowledge of their life cycle and their characteristics has therefore always been important. Most of the research into these insects has been done in northern-Europe where the naturalist movement has been strong since the 17 th century. This has lead to an extended period of study that has been done in this area. Southern Europe does not know this tradition in naturalism and especially on Mallorca the species composition was poorly known until the establishment of the s’Albufera natural park in 1988. Since then a consistent dataset has been build to track the park’s diversity in moths. Though this has lead to the discovery of new species for Spain, the Balearics, Mallorca and even science, little is known about the actual changes in populations and diversity, or what influences these changes.
6 In order to give the research a solid backbone, scientific literature will be used to establish (as much as possible) what is known about the current effects of climate (-change) on moths, the current knowledge on moths in Spain and the Balearics, capture methods, climate change effects and phenological processes. This will be expanded with some literature about the statistical analysis required for the dataset and an overview of the dataset to be used in the analysis.
1.1 Climate change
The Earth’s climate is changing. The IPCC report published in 2007 makes it clear that human emissions are at least responsible for part of this change. Climate change is a global effect that has its impact on all nature, human and non-human alike. It is difficult to scope the range and diversity of changes occurring, as microclimatic changes may not be the same as macroclimatic changes and many climatic factors are linked. The 2007 Assessment report of the IPCC concludes that it is likely (in all following cases) that the yearly mean temperature will increase more than the world-wide average. Within the seasonal temperatures, the increase will be relatively strong during the summer months in the Mediterranean. The number of days in which precipitation is found is expected to decrease for the Mediterranean and this is linked to an increased drought danger ( IPCC, 2007 ). These changes are important for the ecosystems in the Mediterranean. Plants and animals in the Mediterranean are adapted and specialised to a climate with long, warm summers and mild, wet winters. This means that the plants and animals are used to dry conditions for periods at a time, but rely on sufficient precipitation throughout the year to survive. A change in this system can have dramatic effect on these species, as the Mediterranean is a unique ecosystem on its own. Where other plants -like those found in southern France- would have the ability to expand northwards as they encounter changing climatological conditions, the specific Mediterranean pattern would disallow current Mediterranean species to do the same. In addition, warmer temperatures will create a climate that is more alike sub-Saharan Africa than the Mediterranean. This indicates that sub- Saharan species might establish themselves in the Mediterranean, significantly altering the species composition and the Mediterranean ecology. An alternative projection would be adaptation of these species. Within all species there is a certain genetic diversity that allows for a species to quickly adapt to changing conditions. Changing conditions could mean in some species that the genetic make-up of the group changes. This would allow a species of plant to adapt within its current ecosystem to new environmental conditions. The actual effects of climate change on the Mediterranean species therefore needs to be highlighted with specific examples of change in populations. These examples should then be linked both statistically and logically to occurring changes in climatological factors. This is important as
7 many other effects are present in the Mediterranean, both manmade and ecological in origin. Making a clear division between those factors and the climatological factors is therefore critical.
1.2 Moths
For this study, Lepidoptera (from now on referred to as moths) will be the main group of study. The main reason for this is one of opportunity: the Lepidoptera database is by far the most extensive of the park and therefore will most likely allow for the best statistical testing. There is also an Odonata database, but this database is less extensive and has a very limited number of species included. In addition, the species that are included, are mostly very common species such as Common Blue Damselfly ( Enallagma cyathigerum ) and the Lesser Emporer ( Anax parthenope ), which have broad ecosystem allowances. The most important scientific reason is that moths have been intensively studied for many centuries. Much is known about the group and their phenology. This allows for an accurate description of their life-cycle requirements and the conditions that may influence it. Such influence can often be hard to discern, as environmental factors correlate with one another. Feeding moths often are attracted by sweet substances such as tree sap or rotting fruit. Using these substances, or substances alike it (e.g. melasse or whine with white sugar), moths can be attracted to a location. Once there they can be studied and identified. Such traps cannot be left outside for the night and do not produce any density results, because insects can return to the site more than once. To counter such return, the insects can be caught once they arrive on the trapping site, or sedated by adding alcohol to the attracting substance. It is also possible to attract male moths with pheromones, but in order for these pheromones to work, the correct pheromone needs to be matched to the species. This makes the method unsuited for catching multiple species at the same time, though especially Sesiidae are attracted to pheromones ( Waring and Towsend, 2006; Honey and Riddiford, 2003 )
Insects are very vulnerable to changes in their environment. This means that changes in ecological conditions can be observed in insect populations before they can be shown elsewhere. This has been shown in multiple insect groups, but is especially prominent amongst groups which have the ability to spread quickly (especially winged insects). Monitoring insect populations therefore has the potential to be an easy method of following climate change. It is important to know what species respond to what climatological change. Moths are a well known group of insects. They have been studied extensively by naturalists through the ages, but are also well known as pests on many crops. This means that moths as a group
8 make very good study objects. Many of the databases that can be used for the moths are long term (>100 years), which means that they can be compared with significant changes in climate. In addition, the widespread knowledge of moths makes it relatively easy to determine the occurrence of species in both time and space, rather than merely space ( Waring & Townsend 2006 ) Nearly all moths are herbivores, and more of them are mono- of oligophagous. As they are completely dependant upon their juvenile food source, moths do not have an ability to adjust easily to a new host plant. Rather they need to stick to the host, wherever it may occur. As mentioned earlier, changes in climate also give rise to changes in ranges of occurrence. While a certain moths may be dependant upon their hosts, their hosts is not dependant upon them. In addition, plants are generally more tolerant to climatological changes. This means that a moth’s habitat range is not necessarily dependant upon the occurrence of the host ( Barschler & Hill, 2007 ). Moths have been shown to exhibit a polarward range shift ( Parmesan & Yole 2003; Parmesan 2006; Warren et al. 2001; Parmesan et al. 1999; Walther et al. 2002 ), as well as increased polarward migration ( Sparks et al. 2005 ) and changes in fenology ( Parmesan 2006; Stefanescu et al. 2003; Parmesan 2007; Roy & Sparks 2000 ). Most of these changes have been directly linked to the changes in climate, rather than habitat destruction or other non-climate effects. The trends found were not all of equal strength or direction. This is associated with different methods of research, statistics and databases ( Parmesan 2003; Warren et al. 2001 ). The main identifier for change is temperature. As most research, except for Stefanescu (2003), were conducted in northern Europe, such changes need to be linked specifically to winter temperature increases. As Southern Europe is expected to have a more significant effect on summer temperatures, than winter temperatures, the actual effect is expected to be somewhat different. In winter, a decrease in the number of nights with frost, as well as an increase of the mean temperature will lead to a higher survival chance in overwintering moth pupae ( Leather 1984 ). At the same time, a high mean summer temperature will mean an increase in flight days (generally temp > 15C). Moths would therefore be able to establish themselves earlier in the season and have more flight days, assuming their flight moment is not limited by the availability of food. The moth population on Mallorca is a combination of Mediterranean, European and African species. There are roughly 300 species of moths recorded, some of which are indigenous to the Balearic islands. The population also incorporates a number of migrant species, mostly from Africa (including sub-Saharan Africa). Some of the species found are known to be agricultural pests. Overall, the moth population of s’Albufera is unique, as it has a large number of species from diverse backgrounds. This is enhanced by the unique type of ecology (salt marsh) that s’Albufera has.
9 1.3 S’Albufera
Mallorca is located in the Mediterranean sea, off the east coast of Spain. It has a Mediterranean climate. This means that it has mild, humid winters and hot, dry summer periods (Köppen climate classification: Csa) ( Akin 1991 ). The annual average temperature is warm (around 17°C), the average temperature in summer well above 20°C (see fig. 1.01). Precipitation is mainly located during the winter and the annual precipitation is around 570mm. s’Albufera also receives water from run off water and springs located in the park.
AVERAGE MEASURED TEMPERATURE 2002 ºC
30
25
20
15
10
5
0 GEN FEB MAR ABR MAI JUN JUL AGO SET OCT NOV DES
2002 Average 1986-2002 fig 1.5 – Average measured temperature over 2002 compared to the average from 1986 – 2002 of the s’Albufera parc natural at Mallorca.
The nature reserve of s’Albufera is located at the north-east coast of Mallorca and is a sea level wetland with a connection to the sea. It is a former lagoon, now sheltered from the sea by dunes. There is a two-way connection with the sea from the park, creating a gradient of different vegetation communities throughout the park. The main gradient within the park is a salt-fresh gradient. At the coast, there is minimal vegetation consisting of halophytes such as Medicago marina and Sporobolus arenenarius . These plants also grow at the first dune ridge, where salt-spray still creates a saline environment. In subsequent dune ridges, more woody plants are found, which bind the sand on these dunes into a more permanent structure. Dunes are mostly composed of mesotrophic sand, giving rise to a variety of plants. Behind the dunes the land is composed of mainly wetland, with a waterlogged clay soil. The wetland flora growing is typical of the type of ecosystem. In areas that are permanently flooded, there is an abundance of reeds and sedges ( Claudium mariscum ), though there is a variation from the
10 more saline environments to the less saline environments. In addition, there is a fossil dune located in the park where a number of specific plants grow, including a rare orchid ( Orchis palustris ). In the calm open waters duckweed is the dominant species. These climate and habitat conditions make this region suitable for many species that are used to changing dry-wet circumstances, such as species from the Cape. An example of such a species Colotis evangore ( Jordano et al., 1991 ). Within the park, an important dynamic is formed by the surrounding land-use. The fields around the park are mainly used for agriculture and tourism. This has lead to an increasing pressure on the park’s ecosystem. Especially interesting for our research is the continuous addition of nitrates and other nutrients from the surrounding countryside. This is caused by the use of fertilisers, which are used on a ‘more input – more output’ basis. The increased fertiliser run off has caused a high amount of nutrients entering the park, and in turn this has created a high productive ecosystem.
11 2. Materials and methods
2.1 Materials
2.1.2 Moth catching
Moths are normally night dwelling (except a number of day-active Lepidoptera such as most of the unranked clade Rhopalocera ). This makes finding and capturing them as one would do with day- active insects harder (humans don’t see well at night). An alternative method of capture is therefore required. It is known that moths can often be attracted by the use of light-, feed- or pheromone traps. In addition, pupae or caterpillars can be collected and raised into adult moths to be identified. Light traps rely on the moth’s behaviour to fly towards bright light sources. It is unknown why the moths display this behaviour. When moths approach a bright light source, they are disoriented and settle near the light source. A light trap has a lamp placed over a funnel-like box. Below the funnel, there are egg boxes where the moths settle during the trapping. During the morning, the moths can then be safely examined and released after identification. Though this is an effect method of catching moths, not all moths will be attracted to this trap. This means that only a part of the total diversity is sampled. This could be supplemented by employing one or more of the other types of catching and identification ( Waring and Towsend, 2006 ). The moths were caught using a Robinson mercury vapour light trap (fig. 2.1.2.1). The trap uses a 125W MV UV lamp for the attraction of moths. Moths attracted and dazed fall through the trap top into the trap’s body. There they can find shelter from the trap’s light by hiding under a selection of cardboard egg containers. The trap was normally placed on the ground, with an electricity cable connecting the trap to a power source located inside. In 2008 the trap’s set-up was altered, due to the overwhelming presence of Linepithema humile (Argentine ant). The trap was placed on top of a table of which the legs were submerged in water. (see fig. 2.1.2.2). In addition, the electric cable running from the trap to the inside was wrapped with paper between the trap and the place where the cable hit the ground. This paper was then sprayed with pesticides or coated in green soap in order to prevent ants from reaching the trap. The coating/spraying was done daily.
12 fig. 2.1.2.1 – The Robinson trap used at s’Albufera. The trap is not active in the picture.
fig. 2.1.2.2 – The legs of the table on which the trap was set. The legs are submerged in water contained within opened 5-liter water bottles.
The trap was set around dusk (usually between 7 and 9) and left outside for the night. At dawn, the opening slits in the top of the trap (see fig. 2.1.2.1) were closed using paper prior to the trap’s deactivation. The trap’s contents were then examined by lifting the parts of the trap from the trap and noting down the species and number of individuals. Active moths that flew up from the trap were caught manually with insect nets. In 2008 a new system was used in which the trap was covered by a mosquito net to prevent any escapes. Moths that were not directly identified were captures using glass insect tubes. Identified moths that were sufficiently represented in the collection
13 were again released outside. The moths that were not sufficiently represented in the collection were collected and added to the collection. Unidentified specimen were collected and retained for further identification. If the trap got wet during the night, it was dried over the day.
fig 2.1.2.3 – The Robinson trap covered with the mosquito net.
2.1.2 Meteorological data
The meteorological data was measured a s’Albufera, near the Sa Roca area. The exact temperature was measured at 0800 hours, and a minimum and maximum temperature were measured at 1600 hours. At the same time, the evaporation was measured for the day. These meteorological measurements were taken every day since 1986.
The temperature was measured using a U-tube thermometer. Maximum temperature and minimum temperature were measured using pegs that remain on the highest and lowest temperature levels. This way the highest and lowest temperature were indicated by the peg location on the thermometer. This thermometer was placed in a weather hut with lamellas located at 1.5m from the thermometer.
14 2.1.3 Digitalisation
The data collected for both meteorological and moth data was recorded on paper. For the moth data a database was build in Microsoft Access, in which all data was put in from 2001-2007. During this internship, the database has been expanded to include all written moth data records (1991-2008). The database was also adapted to allow for data extraction using queries. The meteorological data was copied and entered into the moth database in a separate file. Written data from 1986-2008 was available, but only 1991-2008 was digitalised. In access, the internal relationships were adjusted to enable a direct link to be formed between the meteorological data and the moth data.
2.2 Analysis
2.2.1 Data exploration
The first step of the analysis will consist of exploration of the data. This will include an overview of the moths found in s’Albufera. In this overview, their absolute and relative numbers per sample will be explored, and their occurrence through the years. The main purpose for this exploration will be establishing the most important, clearly changing species and the general tendency of occurrence of these species by exploring them on a graphical time scale. These species will be classified as the most sensitive species. This will help to limit the amount of species usable for the in depth analysis. The exploration will also include exploration of the meteorological data. This will serve as an overview how the weather patterns change throughout the year. This can then serve as a basis for monitoring actual changes and freak weather events. In addition, the monthly averages will be recalculated for all months to serve as the new data (and to check for mistakes in copying weather data). Any trends in the weather data will be explored as well.
2.2.2 Correlations
The exploration will serve as a base for the rest of the analysis. First of all, the absolute numbers of species per year will be correlated to the various environmental factors, such as minimum temperature, maximum temperature, temperature at 0800 hours and evaporation. This will indicate what factor is specifically important for the moth species to exist. From the database, the moths species with the highest average number of individuals caught per session over all years will be assigned as focal species. The number of focal species will be 20. These focal species will represent the biggest proportion of the number of individuals caught. Due to their abundance, it is expected that these species will show the most clear population dynamics. As the capture method is the same each year, it would be expected that the same fraction of the
15 population is caught each year. From the meteorological database, the average temperature at 0800 hours will be calculated per month. The focal species will then be assigned the average monthly environmental conditions per month for the month of capture organised per session. In addition, each session will be linked to the average temperature at 0800 hours for the month prior, two months prior, four months prior, six months prior and twelve months prior. This dataset will then be subjected to a linear regression analysis with a forward selection entering procedure. The significant factors will establish the months for which the temperature is most important. Of the focal species that are shown to have a significant relationship with one of the prior environmental variables, the meta characteristics will be considered. This analysis of meta factors will then be used to establish whether there is a pattern in the dependence of the moth population data to the environmental data.
16 17 3. Results
3.1 Data exploration
In the data exploration, the first exploration was aimed at the exploration of the absolute data figures, in both temperature, numbers found per species and session captures. This information will be used to establish the focal species for further analysis. These species will also be explored for trends through the years. The environmental factors will be explored for trends as well.
3.1.1 Meteorological data
The meteorological data was explored using a standard scatter graph. The temperature at 0800 hours was chosen as the first representation of the daily temperatures as it reflected the temperatures during the night the best (rather than the maximum and minimum temperature, which gave an approximation of the average daily temperature). All measurements were taken daily between the 1 st of January 1990 and the 27 th of September 2008. The temperature showed the expected fluctuation between the higher temperatures during the summer and lower temperatures during the winters. There was a significantly upward trend in the temperature at 0800 hours during the measurement period (p<0.05).
Temperature through the year
40,00
35,00
30,00
25,00
20,00
15,00
Temperature (C) Temperature 10,00
5,00
0,00 7-5-1990 31-1-1993 28-10-1995 24-7-1998 19-4-2001 14-1-2004 10-10-2006 6-7-2009 -5,00 Year
Temperature at 0800 fig 3.1.1.1 – The temperature at 0800 hours throughout the years, measured as s’Albufera.
18 The average temperature at 0800 hours through the years
17.5
17.0
16.5
16.0
15.5 Temperature (C) Temperature 15.0
14.5 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year fig 3.1.1.1b – The average temperature at 0800 hours per year for all years.
During the day, the minimum and maximum temperature were also taken. The maximum temperature is important as moths become less active during certain temperatures. In addition, some fenological processes depend on a certain minimum temperature threshold. The maximum temperature can indicate whether such a threshold has been crossed. The was no significant trend in the maximum temperature through the years.
Temperature through the year
45,00
40,00
35,00
30,00
25,00
20,00
15,00 Temperature (C) Temperature 10,00
5,00
0,00 7-5-1990 31-1-1993 28-10-1995 24-7-1998 19-4-2001 14-1-2004 10-10-2006 6-7-2009 Year
Maximum temperature fig. 3.1.1.2 – The maximum temperature throughout the years, measured at s’Albufera.
19 The average maximum temperature through the years
24.0
23.5
23.0
22.5
22.0 Temperature (C) Temperature 21.5
21.0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year fig 3.1.1.2b – The average maximum temperature per year for all years.
The minimum temperature is important for the establishment of the absolute cold times during the day. This is especially important for those species who are not resistant against frost. They could experience a drop in numbers shortly after a frost period. The minimum temperature can also serve as a catalyst for fenological development stages of the moths. Also the activity of the moths is dependant on the minimum temperature. This would therefore created a reduced number of captures. There was a significant positive trend of the minimum temperature through the years.
Temperature through the year
35,00
30,00
25,00
20,00
15,00
10,00 Temperature (C) Temperature 5,00
0,00 7-5-1990 31-1-1993 28-10-1995 24-7-1998 19-4-2001 14-1-2004 10-10-2006 6-7-2009 -5,00 Year
Minimum temperature fig. 3.1.1.3 – The minimum temperature throughout the years, measured at s’Albufera
20 The average minimum temperature through the years
14.0
12.0
10.0
8.0
6.0
4.0 Temperature (C) Temperature 2.0
0.0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year fig 3.1.1.3b – The average minimum temperature per year for all years.
Other than the temperature, the evaporation was measured. This environmental factor gives an integrated impression of the environment.
Evaporation through the year
16
14
12
10
8
Evaporation 6
4
2
0 7-5-1990 31-1-1993 28-10-1995 24-7-1998 19-4-2001 14-1-2004 10-10-2006 6-7-2009 Year
Evaporacion fig 3.1.1.4 – Evaporation throughout the years
21 Temperature v.s. Evaporacion
16
14
12
10
8
Evaporation 6
4
2
0 -5,00 0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 40,00 Temperature (C) fig 3.1.1.5 – The temperature plotted against the evaporation, as measured at s’Albufera. The data points were taken over the whole measurement period between January 1 st 1990 – September 27 th 2008.
As can been seen in fig. 3.1.1.4, the evaporation through the year follows roughly the same pattern as the temperature. This is a logical result as the physical process of evaporation is linked to the temperature. The graphical correlation between the two factors (shown in fig. 3.1.1.5) clearly shows the trend that would be expected. The explanatory value of this correlation is low (15%), as there are more factors influencing the actual evaporation. On of these factors is the actual precipitation. Though this is linked to the time of the year (and therefore temperature, see Literature), it will have a certain amount of actual correlation.
3.1.2 Species data
The focal species were selected from the access database. The focal species selected represent an average of 40.9% of the total number of individuals caught (see table 3.1.2.1 in Appendix 1). This average percentage of individuals caught showed an optimum trend through the years (see fig. 3.1.2.1).
22 Percentage individuals caught in focal species
80
70
60
50
40
30 Percentage (%) Percentage
20
10
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year R2 = 0,7333 fig. 3.1.2.1 – The percentage individuals caught of the focal species.
The focal species were individually explored to get an impression of the yearly amounts caught. This was done for all species, and a linear trend was explored for all species to see if they had a tendency to be found more often with the years. Fig 3.1.2.2 shows average number of individuals caught over all 20 focal species, figure 3.1.2.3 shows the average number of individuals caught for all species, showing a similar trend. As the percentage of the total number of individuals caught represented by the focal species was not the same throughout the period of measurement, the total number of individuals caught was also used as a comparison (see fig. 3.1.2.4). It showed a similar trend as the other graphs.
23 Average number of individuals caught per session for all focal species
350
300
250
200
150
100 Numberof individuals
50
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year R2 = 0,6285 fig 3.1.2.3 – Average number of individuals caught per session for all focal species, from 1993 to 2008-11-11
Average number of individuals caught per session
250
200
150
100 Number Number of individuals 50
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year R2 = 0,4481 fig 3.1.2.3 – Average number of individuals caught per session, from 1993 to 2008-11-11
24 Total number of individuals caught
14000
12000
10000
8000
6000
4000 Number Number of individuals
2000
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year R2 = 0,6385 fig 3.1.2.4 – Total number of individuals caught per year at s’Albufera from 1993 – 2008. The R 2, is the calculated R 2 of the trend line.
These positive trends give the impression that there is both an increase in the number of individuals caught, as well as the number of species found. This was explored by averaging the number of species found per session, and then averaging this per year. The result was explored in fig. 3.1.2.5, where a clear positive trend can be seen in the average number of species per session. This suggests that the biodiversity in s’Albufera is increasing.
Average number of species through the years
7
6
5
4
3
2 Av. Av. number of species
1
0 1993 1995 1997 1999 2001 2003 2005 2007 Year R2 = 0,5399 fig 3.1.2.5 – the average number of species per session per year.
25 The absolute numbers of species was found to be increasing with time (see fig. 3.1.2.6). This includes only the Lepidoptera species found for each year. The absolute number of individual species found in all years in uncertain, as a number of individual species will be found regularly. The trendline drawn was found to represent a significant increase in de total number of species per year over the years (p<0.05).
The number of species caught through the years
350
300
250
200
150
100
50 Number of speciesNumber caught (#) 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year fig 3.1.2.6 – The absolute number of Lepidoptera species caught in the s’Albufera trap.
3.2 Correlations & Regressions
The relationship between the temperature and the mouth population is the most important. The moth population is expressed in different ways. The first that will be examined is the relationship between the average temperature per year and the amount of moth species caught per year (see fig. 3.1.2.6 for moth species numbers and 3.1.1.1 – 3.1.1.3 for the temperature through the years). Fig. 3.2.1a-c shows a plot of these two factors, the temperature is split out into the minimum temperature, maximum temperature and the temperature at 0800 hours. A general correlation was run over the factors considered and the number of species found was significantly correlated with all temperature factors, except for the maximum temperature. In addition, the number of species was significantly correlated with time (year). A linear regression was run for all environmental factors as independent variables and the number of species as dependent, using a forward insertion of the independent variables. The only significant explanatory variable for the number of species found was the average minimum temperature (p<0.01, R 2 = 39%). A linear regression was also run to see what the explanatory value of the time was for the average minimum temperature. This regression showed a significant relationship (p<0.05) with a explanatory value of 55%.
26 Average minimum temperature hours versus species number per year
350 300 250 200 150 100
Number of speciesNumber (#) 50 0 10.0 10.5 11.0 11.5 12.0 12.5 13.0 Temperature (C) fig 3.2.1a – The amount of species caught per year plotted against the minimum temperature in C.
Average temperature at 0800 hours versus species number per year
350 300 250 200 150 100
Number of speciesNumber (#) 50 0 14.5 15.0 15.5 16.0 16.5 17.0 17.5 Temperature (C) fig 3.2.1b – The amount of species caught per year plotted against the temperature at 0800 hours in C.
27 Average maximum temperature versus species number per year
350
300 250
200 150
100
Number of speciesNumber (#) 50
0 21.0 21.5 22.0 22.5 23.0 23.5 24.0 Temperature (C) fig 3.2.1c – The amount of species caught per year plotted against the maximum temperature in C.
Correlations
Year Temp0800 MinTemp MaxTemp Biodiversity Pearson Correlation .923(**) .531(*) .673(**) .376 Sig. (2-tailed) .000 .034 .004 .152 N 16 16 16 16 [ ** Correlation is significant at the 0.01 level (2-tailed).] [ * Correlation is significant at the 0.05 level (2-tailed).] Table 3.2.1 – The correlation factors between the biodiversity (expressed as number of species caught per year) and the explanatory factors year, temperature at 0800, maximum temperature and minimum temperature.
The second correlation was done with the focal species and the number of individuals caught. This correlation was run based on the monthly averages of both individuals caught per species and the temperature factors. The temperature factors used were: minimum temperature, maximum temperature, temperature at 0800 hours. Temperature at 0800 hours was split out towards the history of the temperature. Used in the analysis were the factors: average temperature of the month of capture (0800-0), the month prior (0800-1), 2 months prior (0800-2) and for the months 4,6 and 12 prior (0800-4, 0800-6 and 0800-12). The factors and the dependent variable were correlated with one-another to establish relationships. All individual factors were found to be significantly correlated. The factors were then used in a regression with forward selection to distinguish the co-correlation between the factors. The average temperature of the month prior to the capture of the moths was found to be the most significantly related factor for all species combined. The individual species were then also placed through the forwards regression.
28
Species Significant regression(s) Direction Total R2 Acrobasis obliqua None N/A N/A Agrotis puta 0800-6/0800-4 .324 / -.156 .539 Bactra lancealana 0800-1 .159 .779 Crocidosema plebejana None N/A N/A Dichomeris acuminatus None N/A N/A Eilema rungsi None N/A N/A Gypsonoma minutana 0800-2 .209 .494 Hellula undalis 0800-2 .158 .602 Leucania obsoleta* 0800-1 / 0800-2 3.080 / -2.128 .411 Leucania zeae** 0800-12 / 0800-6 1.331 / -.533 .709 Nola squalida 0800-2 .234 .451 Nomophila noctuella** 0800-12 .213 .347 Oncocera semirubella 0800-1/0800-4 .674/-.445 .547 Plutella xylostella** 0800-0/0800-2 .326/-.156 .551 Rhizedra lutosa 0800-2 .150 .720 Scopula minorata 0800-2 .120 .339 ochroleucharia Spodoptera cilium 0800-2 .449 .507 Spodoptera exigua 0800-2 .469 .303 Udea ferrugalis** 0800-6 .136 .845 Xestia xanthographa 0800-2 .141 .644 Table 3.2.2 – Regression results for all focal species. * indicates regression was run with a significant constant factor. **Indicate species mainly native to the African continent or a migrant species
29 30 4. Discussion
4.1 Data
The data of the moth database is very straight forward. It has been collected on a regular basis for a long time and always with the same method. This gives a consistent basis to the information and allows for a good year-to-year comparison. The same goes for the meteorological data. The main problem with the dataset is that only a single location has been measured. This disallows for a broader generalisation to be drawn for multiple places on Mallorca.
4.2 Regressions
Already during the measurements, it became clear that temperature in itself has an effect on the amount of moths we captured. This could consistently be seen on a daily basis. For the analysis, this posed a problem, as the temperature dependence is more activity-related than population related. Because of this, no direct comparison was made between the daily temperatures and the moths caught. The daily temperature showed a steady increase in both minimum and maximum temperature over the years. The temperature at 0800 hours was related to the minimum temperature (which is likely due to the temperature at 0800 hours being close to the average minimum temperature for a day at 0400 hours than the average maximum temperature at 1400- 1500 hours). The temperature was measured in a consistent fashion, allowing for an accurate picture of the changes in temperature through the year and over the years to be formed. The number of species found each year is an indication of the overall present biodiversity in the park. The statistical analysis of the yearly number of species caught indicates that the biodiversity in the s’Albufera park is increasing. This is due to the changing conditions represented by the changing temperature, but also the increasing salinity of the park (Jeroen’s artikel ) and the changes in management. How strongly the temperature influences the individual species depends on the species, but as a whole it was found specifically related to the average minimum temperature through the day. This seems logical and in line with the earlier observation that moth populations mainly depend on minimum temperatures for activity and surviving the winter. When the focal species are examined, the individual species showed a distinct difference between migratory species and the species native to s’Albufera. Overall the average temperature at 0800 two months prior to the capture is an important indicator of the amount of individuals captured. This has likely to do with the survival of the caterpillars during this time, a low temperature making it harder for them to survive. All the related factors showed a clear positive correlation,
31 indicating that colder temperatures lessen population numbers. Also the temperature of one and four month past are important, due to the range that exists in development time of the caterpillars. This is likely the same explanation why the migratory species are more related to the sixth month prior to capture. These species will likely have needed time to travel to s’Albufera, but are still mostly dependent on the time of their development for the actual numbers caught. Overall, the temperature represents a significant, but not necessarily critical factor for the species and their abundance. 20% of all species (4/20) has a strong relationship (R 2>75%) with a temperature factor, 50% has any noticeable relationship (R 2 >50%) with the temperature factor. This suggests that there are certainly other factors contributing to the abundance of these species. Such other factors would be expected as there are many phenological requirements for each species. It does indicate that temperature is important. In itself, temperature can be considered a causal variable, but insects are a integration of their environment. Temperature can have an effect on a population while the population itself is not directly affected by the change. Naming temperature directly causal is therefore not justified by the results. In general the database has produced very much the results that would expected and was found to be reliable.
4.3 Further discussion
This particular study was limited by the fact that the only true factor that was analyzed was the temperature, in one form or the other. Moth populations depend on more factors than merely temperature, though our tests seemed to have shown that at least a number of species are very dependant on it. All insects, however, are an integration of their environment, and a high dependence on temperature suggests more the stability of the other factors influencing the species’ abundance, than that temperature is the only true variable. Within s’Albufera, the management and the environment is continuously changing. The temperature is actually one of the few non-human factors in the park. Others such as management both inside and outside the park have not been accounted for at all. It is likely that if such things as management, eutrification, water balance and precipitation are adequately quantified, they will give good results regarding the relationship of (some of the) moth species relationship with the environment. This could be a potential for further research as the park could use such monitoring schemes on a greater scale in this way. The database itself has become very adaptable to new situations. Basically any data relying on a date, being environmental or species-wise, can be added by the creation of extra tables or columns. In this way, the research could also be expanded beyond the borders of the moths. An example of future research could be the relationship between the temperature, precipitation and the
32 water quality of the s’Albufera park in relation to the presence of Odonata (Dragonflies). In the recent years, some research has been done on Odonata in the park, though not extended database is available for use. This research could also be used to see if the more broadly found trends of climatological dependence are similar for both moths and dragonflies ( Hickling et al, 2004 ). Dragonflies have a slightly different life history than moths and are more dependant upon the water conditions during their development, and this development is often longer (3-5 years). The water quality has been monitored for a longer time already in s’Albufera, so a consistent dragonfly survey would likely allow connections from 2003 and upwards to be made. As mentioned in the materials and methods, the trap had to be secured against the Argentinian ants that were present in the park. According to some of the park staff, they were having their ‘Olympic year’, indicating that the ants have better and lesser years. Seeing that the Argentinean ant infestation of s’Albufera is present and ongoing, research into the exact effects of the exotic species invasion could be important to determine the best methods of management. The ant population could, for example, be measured and then be compared to the abundance of the moth species in the park.
33 5. Concluding remarks
Working with the s’Albufera moth database has been a very rewarding experience. The database is not perfect, but the information stored in it is of high quality. It would be very reasonable to suspect that it could very easily be used in a range of different topics for future research. In addition, the database can be set up in such a method that it can easily produce reports on a yearly basis showing changes in the moth database. The moth population on Mallorca seems to be changing in a positive way by showing an increase in biodiversity. Though some of the focal species in this particular research can be linked in a strong degree to the various environmental factors, it is very unlikely that the management of the park does not have its role in the moth population. This role should be further explored in future research, as it could point to the success or failure of management practices that concern the moth population. Such results could then be used as a guideline.
Another research that I would personally recommend, is looking into the relationship of the moth population and environmental factors combined with various other species from distinct species groups. These other species groups could be Odonata, Coleoptera, birds, fish, hydrophytes or other insects. As these comparisons do need to be done on a year to year basis, it would be important to start measurements soon and in a sustainable, easy fashion (similar to the Robinson trap). Any link found could be used to establish the moths as a general indicator species for numerous species groups, therefore allowing general management effects to be measured.
34 35 Appendix 1 – Tables
Species 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 Avg Spodoptera exigua 25 38 180 174 29 4 75 69 529 1431 150 553 1584 38 45 328,27 Spodoptera cilium 33 155 55 36 49 339 156 83 411 386 391 269 873 187 29 230,13 Nola squalida 10 11 85 24 15 10 43 248 64 126 207 166 820 528 456 42 178,44 Leucania obsoleta 79 137 92 26 111 94 189 222 753 76 5 162,18 Eilema rungsi 31 48 26 24 69 64 289 100 50 246 274 351 48 124,62 Oncocera semirubella 1 1 41 109 44 2 3 33 153 90 14 31 127 217 465 693 126,50 Leucania zeae 2 3 154 80 155 12 54 54 267 187 95 105 263 162 114 86 112,06 Acrobasis obliqua 2 8 19 8 24 127 184 23 145 128 263 527 222 53 3 115,73 Nomophila noctuella 16 5 57 270 2 16 48 54 44 113 441 111 48 361 55 20 103,81 Gypsonoma minutana 5 7 8 38 29 234 148 202 105 114 111 91,00 Bactra lancealana 6 44 76 56 26 57 161 122 110 129 224 57 89,00 Plutella xylostella 2 3 50 26 8 29 38 83 128 93 200 144 54 250 156 41 81,56 Dichomeris acuminatus 10 13 206 12 122 91 46 70 154 73 30 75,18 Hellula undalis 6 64 11 18 151 15 64 77 40 91 172 128 61 69,08 Scopula minorata ochroleucharia 2 18 14 16 9 9 21 31 445 46 95 145 96 61 27 69,00 Crocidosema plebejana 11 15 16 39 117 30 98 40 77 76 219 89 68,92 Rhizedra lutosa 62 20 36 60 74 101 56 60 46 31 131 187 74 2 67,14 Agrotis puta 59 27 39 3 21 13 315 43 30 83 59 27 56 224 17 34 65,63 Udea ferrugalis 1 73 34 30 27 34 36 118 134 87 93 67 112 86 40 64,80 Xestia xanthographa 14 5 4 10 11 25 25 26 11 79 102 200 236 120 89 3 60 table 3.1.2.1 – Total number of individuals caught per focal species
36 37 Appendix 2 – Species focal species
In this Appendix, a number of specific species is explored. These species were marked with specific characteristics of interests, such as being migrants, invasive or disappearing. All species were explored in both absolute numbers (total number of individuals per year) and relative numbers (number of individuals per session per year), as the number of session was not the same each year.
Utetheisa pulchella
Utetheisa pulchella is an sub-Saharan African species. It is known as a migrant, and analysis of the species numbers suggests that the species has been a regular migrant, or breeding species in s’Albufera during the mid-90’s. The species has been caught less frequent during the new millennium, suggesting migrations are less frequent and/or that the species does no longer breed in s’Albufera. The caught number of individuals in both absolute and relative numbers are shown in fig. A2.1.
Absolute number of individuals found for Utetheisa pulchella
25
20
15
10 Number Number of individuals 5
0 1993 1995 1997 1999 2001 2003 2005 2007 2009 Year fig A2.1a – The absolute numbers of individuals found through the years for Utetheisa pulchella .
38 Utetheisa pulchella R2 = 0,6323
2,5
2,0
1,5
1,0
Avg numberAvg of individual 0,5
0,0 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year fig A2.1b – The relative number of individuals caught per session per year of Utetheisa pulchella .
Leucania joannisi
Leucania joannisi is a south-european species that was indicated to be a declining species by N. Riddiford. The data exploration showed that indeed the species shows a clear decline in time.
Absolute number of individuals found for Leucania joannisi
250
200
150
100
R2 = 0,402 50 Number Number of individuals
0 1993 1995 1997 1999 2001 2003 2005 2007 2009
-50 Year fig. A2.2a – The absolute numbers of individuals found through the years for Leucania joannisi . This species was marked by N. Riddiford as a possibly declining species. The trend line was added to give an impression of the change.
39 Leucania joannisi
9,0
8,0
7,0
6,0
5,0
4,0
3,0
Avg numberAvg of individual 2,0
1,0
0,0 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year fig. A2.2b – the average number of individuals caught per session.
Other species
Absolute number of individuals found for Mythimna languida
6
5
4
3
2 Number Number of individuals 1
0 1998 2000 2002 2004 2006 2008 Year fig A2.3 – The absolute numbers of individuals found through the years for Mythimna languida . This species is a sub-Saharan, tropical species. No trend line was added due to the low number of individuals found.
40 Absolute number of individuals found for Heliothis nubigera
4,5
4
3,5
3
2,5
2
1,5
Number of individuals 1
0,5
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year fig A2.4 – The absolute numbers of individuals found through the year for Heliothis nubigera . This species is a migrant into Europe. It was found in especially high numbers in Britain in april/may 2006 and has likely bred successfully there (finding numbers in 2007)(UK Moths, 2008 ). The s’Albufera numbers reflect this same event. It is an eastern species, native to Europe. The average number of individuals caught was 1.
Absolute number of individuals found for Chrysodeixis chalcites
2,5
2
1,5
1 Number Number of individuals 0,5
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Year fig. A2.5 - Absolute numbers of individuals found through the years for Chrysodeixis calchites . This is a species that feeds primarily on cotton and tomato. The low number of individuals does not allow for any speculation of trends in their numbers
41 Hadula sodae
9
8
7
6
5
4
3
Avg numberAvg of individual 2
1
0 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year fig. A2.6 – Average numbers of individuals found through the year for Hadula sodae . This is a salt-march species. No trend line was added, as the species shows signs of population dynamics that do not give a clear trend.
42 43 Literature
- Akin W.E., 1991. Global Patterns: Climate, Vegetation, and Soils. Norman and London. ISBN 0-8061-2309-5. 370pp.
- Barschler B. & Hill J.K., 2007. Role of larval host plants in the climate-driven range expansion of the butterfly Polygonia c-album. Journal of Animal Ecology 76 (3): 415-423
- Brehm G. & Axmacher J.C., 2006. A Comparison of Manual and Automatic Moth Sampling Methods (Lepidoptera: Arctiidae, Geometridae) in a Rain Forest in Costa Rica. Environmental Ecology 35 (3): 757 - 764.
- Hickling R., Roy D.B., Hill J.K. & Thomas C.D., 2005. A northward shift of range margins in British Odonata. Glob. Change Biol. 11:502–6
- Holyoak M., Jarosik V. & Novák I., 1997. Weather-induced changes in moth activity bias measurement of long-term population dynamics from light trap samples. Entomologia Experimentalis et Applicata 83 (3): 329 - 335
- Jordano D., Retamosa E.C., Fernandez H., 1991. Factors facilitating the continued presence of Colotis evagore (Klug 1829) in southern Spain. J. Biogeogr. 18:637–46
- McCarty J.P., 2001. Ecological Consequences of Recent Climate Change. Conservation Biology 15 (2): 320-331
- Parmesan C., Ryrholm N., Stefanescu C., Hill J.K., Thomas C.D., Descimon H., Huntley B., Kaila L, Kullberg J., Tammaru T., Tennent W.J., Thomas J.A. & Warren M., 1999. Poleward shifts in geographical ranges of butterfly species associated with regional warming. Nature 399: 579–583
- Parmesan C., 2006. Ecological and Evolutionary Responses to Recent Climate Change. Annual review of Ecology, Evolution and Systematics 37: 637-669.
- Parmesan C., 2007. Influences of species, latitudes and methodologies on estimates of phenological response to global warming. Global Change Ecology 13 (9): 1860 - 1872
44
- Pullin A.S., 1995. Ecology and conservation of butterflies. Chapman & Hall publications. ISBN 0 412 56970 1
- Raimondo S., Liebhold A.M., Strazanac J.S. & Butler L., 2004. Population synchrony within and among Lepidoptera species in relation to weather, phylogeny, and larval phenology. Ecological entomology 29 (1): 96 - 105
- Robin Baker R. and Savody Y., 1978. The distance and nature of the light-trap response of moths. Nature 276: 818 - 821
- Roy D.B. & Sparks T.H., 2000. Phenology of British butterflies and climate change. Global Change Biology 6 (4): 407 - 416
- Sparks T.H., Yates T.J., 1997. The effect of spring temperature on the appearance dates of British butterflies 1883–1993. Ecography 20:368–74
- Sparks T.H., Roy D.B. & Dennis R.L.H., 2005. The influence of temperature on migration of Lepidoptera into Britain. Global Change Biology 11 (3): 507 - 514
- Sparks T.H., Dennis R.L.H., Croxton P.J. & Cade M., 2007. Increased migration of Lepidoptera linked to climate change. European Journal of Entomology 104: 139-143.
- Stefanescu C, Peñuelas J, Filella I., 2003. Effects of climatic change on the phenology of butterflies in the northwest Mediterranean Basin. Glob. Change Biol. 9:1494
- Thomas A.W. and Thomas G.M., 1994. Sampling strategies for estimating moth species diversity using a light trap in a northeastern softwood forest. Journal of the Lepidopteran Society 48 (2): 85 - 105
- UK Moths (13-11-2008, ,03-12-2008, 04-12-2008) - http://ukmoths.org.uk/show.php?id=4450 – Information on the collection of individuals from Heliothis nubigera .
45 - Visser M.E. & Both C., 2005. Shifts in phenology due to global climate change: the need for a yardstick. Proceedings of the Royal Society B-Biological Sciences 272, 2561-2569
- Vives P.T., 1996. Monitoring Mediterranean wetlands: a methodological guide. Medwet Publication. ISBN 1-900442-04-3. 150pp.
- Walther G-R et al., 2002. Ecological responses to recent climate change. Nature 416: 389 - 395.
- Waring P. & Townsend M., 2006. Nachtvlinders. Tirion Uitgevers. ISBN 976-90-5210-625-0 (Dutch translation). 415pp.
46