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Protecting Ireland’s Oligotrophic Lakes

By Emma Gray, Heather Lally and Giovanni Cappelli

Figure 1 Oligotrophic lakes in the Owenduff Nephin Special Area for Conservation (Photo credit: Heather Lally)

This blog post was written for the Peatlands Gathering which is occurring virtually 7th-9th October.

The aim of the gathering is to share knowledge and understanding of peatlands within Ireland and the key messages gathered from the event will be presented at COP26.

If you would like to attend the event please follow this link.

Peatland ecosystems contain many freshwater lake habitats (Figure 1), which harbour a suite of specialist plants and animals important for biodiversity. Two freshwater lake habitats found in blanket bogs along the west of Ireland are protected under the European Union (EU) Habitats Directive as ‘Oligotrophic waters containing very few minerals of sandy plains (Littorelletalia uniflorae)’ (3110 lake habitats) and ‘Natural dystrophic lakes and ponds’ (3160 lake habitats). Ireland is a stronghold for both habitats within Europe due to our extensive areas of blanket bog, but unfortunately the conservation status of 3110 and 3160 lake habitats are bad and inadequate, respectively.

Currently, the composition of macrophyte communities (Figure 2) are used to characterise these lake habitats, but in reality, these lakes host a wide range of ecological elements which are poorly described. Therefore, the aims of the EPA funded PeAT Lakes project are to determine whether 3110 and 3160 lake habitats can also be characterised using macroinvertebrate, zooplankton and algal communities and examine relationships between these biota and their water chemistry. By doing this we aim to evaluate the environmental conditions necessary and thus propose monitoring methods and assessment tools that will maintain these protected lake habitats in a favourable conservation status.

We are currently monitoring 24 lakes clustered in the Owenduff/Nephin (Co. Mayo) and Connemara Bog Complex (Co. Galway) Special Areas of Conservation (SAC’s), where monthly sampling of various water chemistry parameters is conducted along with two biological surveys, one in Spring and Summer respectively. So far, we have found that these lake habitats are oligotrophic in nature and contain a rich diversity of algae (Figure 3), zooplankton (Figure 4) and macroinvertebrates (Figure 5).

Figure 3. Desmids (a group of algae) commonly found within these lake types (Photo credit: Emma Gray).

Figure 4. Zooplankton live in the water column and are abundant within these lake types (Photo credit: Sadhbh Mahony).

The team (Figure 6) are currently working through the identification of these biological samples and you can keep up to date with our findings by following us on twitter @PeAT_Lakes.

Figure 6. The Peat Lakes Team sampling for water chemistry and biology. (Photo credit: Giovanni Cappelli)

Sampling the aquatic insects of the Connemara and Mayo peatland lakes

By Aaron Skehan

Aaron Skehan, third year student at Galway-Mayo Institute of Technology (GMIT)

Here Aaron tells us about his experience as an intern on the EPA funded PeAT Lakes Project

I am currently working with the PeAT Lakes project as a student intern of Applied Freshwater and Marine Biology at GMIT. My main role is to investigate the general structure of macroinvertebrate communities in oligotrophic peatland lake habitats (Annex 1, 3110 and 3160) as part of my 4th year thesis project.

The goal of the project is to gather data on the water chemistry and biota of these peat lakes and, from that data, establish a set of baseline parameters to be used in the conservation of these habitats. The lakes in Irish peatlands have unique water chemistry and ecological communities, and it is not well known what differentiates ‘good’ quality lakes from ‘bad’ quality lakes in peatland systems.

Figure 1. One of the pools sampled from the Owenduff/Nephin SAC (Photo credit: Aaron Skehan)

Macroinvertebrate diversity is an important indicator of the conservation status of peatland lakes. Oligotrophic lakes are nutrient poor and therefore limited in the plant life they can support. This has an impact on the structure of macroinvertebrate communities, and many rare insect species are unique to these habitats. There is a need for a greater understanding of macroinvertebrate communities in these habitats so that effective conservation plans can be set in place for their continued protection.

Figure 2 A damselfly having just emerged from the water, sheds it’s larval skin, leaving an empty husk behind. Damselfly larvae are common predators in peat lakes (Photo credit: Aaron Skehan)

We have collected macroinvertebrate samples from various upland and lowland peat lakes in the Owenduff/Nephin and Connemara regions (Figure 1). Samples were taken using a sweep net. One minute sweeps were performed for the pools and three minute sweeps for the larger lakes. The project hopes to determine if there is any difference in macroinvertebrate diversity between lowland 3110 and 3160 lake habitats. We are currently sorting through the samples collected in May and dividing organisms into their general families (Figures 2 and 3).

I chose this project as a work placement because I find Irish raised blanket bog fascinating and wish to be involved in their conservation. They are a unique habitat that have been significantly reduced throughout Ireland and wider Europe due to a variety of anthropogenic activity, mainly afforestation, peat cutting and over grazing of livestock. Despite being a relatively common habitat in Ireland, there are few natural or near-natural blanket bogs remaining in Europe, and we have a duty to protect them for future generations. They are objectively beautiful, full of unique flora and fauna, and my time spent doing fieldwork with the PeAT Lakes team has only increased my appreciation for these wonderful habitats.

Figure 3 Bogbean (Irish: Bearnán lachan) is common in the shallow pools and sphagnum hollows and provides food for the caterpillars of elephant hawkmoths (Photo credit: Aaron Skehan)

Keep up-to-date with Aaron’s research @PeAT_Lakes


Sampling the abundance of zooplankton in the Owenduff/Nephin and Connemara region

By Sadhbh Mahony

Sadhbh Mahony, third year student at Galway-Mayo Institute of Technology (GMIT)

Here Sadhbh tells us about her experience as an intern on the EPA funded PeAT Lakes Project

I am currently a third-year student at GMIT, studying Applied Freshwater and Marine Biology. For my third-year placement, I chose to intern for the EPA PeAT Lakes project which aims to characterise peatland oligotrophic lake habitats (Annex 1 3110 and 3160) using physical, chemical and biological data. My role is to characterise the zooplankton communities in these oligotrophic lakes for my fourth-year thesis project.

We are looking at the zooplankton communities to see if we can use them to distinguish between 3110 and 3160 lake habitats as defined under the EU Habitats Directive. We are also trying to develop a solution to recommend a conservation assessment framework to ensure a long-term achievement of favourable conservation status for these lakes.

Zooplankton play a vital role in aquatic ecosystems as they transfer energy from lower trophic levels to higher levels1. The abundance and composition of zooplankton is structured by resources, competition and the pressure of predation and the structure of zooplankton communities can also be affected by low dissolved oxygen concentrations1.

Figure 1 One of our sample sites in Connemara
(Photo credit: Sadhbh Mahony)
Figure 2 Taking a sample at one of our lake sites
(Photo credit: Sadhbh Mahony)

Sampling took place in the Owenduff/Nephin and Connemara region (Figure 1) within Special Areas of Conservation (SAC’s). There are 24 lakes to be sampled and we have just completed our Spring biological survey.

To capture zooplankton, I used a zooplankton net with a mesh size of 52 µm. To take the samples I had to pull the zooplankton net horizontally from a fixed platform. I did this five times for each sample to try and keep my results as consistent as possible (Figure 2). One sample had to be taken from each pool and three samples were taken from each lake.

After collecting my samples I started practicing zooplankton identification using the inverted microscope at GMIT. Figure 3 is a Copepod molt, it does not have an organism inside it as it is the exoskeleton of a copepod2. Figure 4 is a Chydorid which are widely distributed and are usually found in the littoral/ benthic habitat and they often become pelagic in eutrophic systems2. Figure 5 is a Bosmina which are usually found in the epilimnion of lakes and in bog pools2 and figure 6 is a rotifer. I have now started to count the samples I collected, and I am starting to notice a difference in abundance and community composition between lakes.

Figure 3 Copepod molt (Photo credit: Sadhbh Mahony)
Figure 4 Chydorid (Photo credit: Sadhbh Mahony)
Figure 5 Bosmina (Photo credit: Sadhbh Mahony)
Figure 6 Rotifer (Photo credit: Sadhbh Mahony)

Following interning on this project, I would like to continue my studies in freshwater biology as I have really enjoyed the experience so far and I am looking forward to sharing my findings with you.

Keep up-to-date with Sadhbh’s research @PeAT_Lakes

References

  1. Cfb.unh.edu. (2021). An Image-Based Key to the Zooplankton of the Northeast (USA). [online] Available from: http://cfb.unh.edu/cfbkey/html/index.htm. [Accessed 13th May 2021].
  2. Fetahi, T., Mengistou, S. and Schagerl, M., (2011). Zooplankton community structure and ecology of the tropical-highland Lake Hayq, Ethiopia. Limnologica, [online] 41(4), 389-397. Available from: https://www.sciencedirect.com/science/article/pii/S0075951111000314.  [Accessed 13 May 2021].

A Passion for Nature and Invertebrates

By Giovanni Cappelli

Giovanni Cappelli, PhD Researcher on the EPA funded PeAT Lakes Project based at the Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology

Here Giovanni tells us about his previous experiences working in freshwater ecosystems and what has drawn him to continue his research on Beetles (Order Coleoptera).

I began my career as a biologist at the Department of Science at Università degli studi Roma Tre, where I focused on developing skills and knowledge on many of my passions such as zoology, ecology and conservation. Following this, I graduated with a Master in Biodiversity and Ecosystem Management in 2017/2018.

From the beginning, I decided to get as much experience in the field as I could, therefore I participated in many monitoring programmes, supporting more experienced scientists in their research projects. I helped with the sampling of many kind of small fauna, especially freshwater vertebrates such as newts (Figure 1) and invertebrates like dragonflies (Figure 2). These projects focused on studying the relationship between man-made environments and faunal communities in protected areas such as Valle di Rio Fiume (Site code: IT6030004) a Special Areas of Conservation (SACs) in southern Italy (Figure 3) where traditional pastoral activities help maintain a sustainable level of human livelihood while preserving nature.

Figure 3 Rio Fiume’s valley SAC in Latium region, Central Italy (Photo credit: Giovanni Cappelli)
Figure 1 Adults Lissotriton vulgaris meridionalis (Photo credit: Giovanni Cappelli)
Figure 2 An adult Crocothemis erithraea resting near a drinking trough, an important breeding site for many species (Photo credit: Giovanni Cappelli)

As part of my master’s degree, I conducted my own study into the ecology of Claviger apenninus (Coleoptera – beetle species) and their relationship with ants of the Lasius genus (Figure 4). I studied how their morphological, physiological and behavioural adaptations allowed the Staphylinidae to exploit its host and develop a parasitic association. The adaptations of C. apenninus are a small but very hard and compact body, which gives it protection, and most importantly the ability to produce the same chemical signature of their ant host therefore, giving the beetle the ability to be recognised as a kin when approached by an ant. Thanks to the exploitation of its ant host, the benefit of being an obligate parasite, completely dependent on its host, ensures the long-term survival of C. apenninus

Figure 4 A Claviger apenninus interacting with its host, Lasius distinguendus (worker and larvae) (Photo credit: Giovanni Cappelli)

Following graduation, I interned at Centro Agricoltura Ambiente, where I experienced professional life monitoring the expansion of invasive mosquito species Aedes albopictus (Asian tiger mosquito) (Figure 5) in natural and anthropogenic freshwater environments in northern Italy. Here, I also collaborated in the developing of techniques to manage the spreading of this species with a view to lowering their impact on human health

Figure 5 Aedes albopictus pupae (female left, male right) (Photo credit: Giovanni Cappelli)

For the PeAT Lakes project, I will characterise the physico-chemical and morphological features of oligotrophic lakes as well as their macroinvertebrates mainly Orders Coleoptera (beetles) and Odonata (dragonflies and damselflies), and macrophyte community compositions. This will be the first-time baseline data will be used to characterise protected oligotrophic lake habitats 3110 and 3160 in Ireland and will create reference conditions on which future monitoring programmes and conservation measures are determined. My research aims to provide a set of monitoring methods and recommendations that will ensure these lake habitats can be protected for future generations.

Keep up-to-date with Giovanni’s research @PeAT_Lakes


Phytoplankton: Using A Secret Micro Underworld To Reveal Large Climatic Impacts in Lakes

By Dr Emma Gray

Dr Emma Gray, Postdoctoral Researcher on the EPA Funded PeAT Lakes Project based at the Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology

Here Emma tells us about her previous experiences working with phytoplankton and what has drawn her to continue with her research.

Prior to moving to Ireland to join the PeAT Lakes project, I completed my PhD at the UK Centre for Ecology & Hydrology.

My PhD research investigated the impacts of climate change and storm events on the community composition and vertical distribution of suspended algae (phytoplankton) within the lake water column. Having had no previous experience in algal identification before starting my PhD I was initially daunted by the task, particularly when I realised how many species there were (estimated in the thousands!1). After lots of practice, I soon began to enjoy my time behind the microscope, and as I saw rapid changes in the community composition between samples, I realised what a valuable indicator they are for detecting ecosystem changes induced by climate, weather and pollution.

Phytoplankton are small microorganisms that are suspended and mixed in water forming the foundation of the aquatic food web1. Phytoplankton are very diverse in size and morphology, they can exist as single cells (Fig. 1) or in colonies (Fig. 2), and they have features of both plants and animals. Like plants, phytoplankton contain chlorophyll to capture sunlight energy for photosynthesis, but some species also get their energy by ingesting bacteria in addition to photosynthesising which is called mixotrophy2. Phytoplankton also have different levels of motility, some rely on turbulence to keep them entrained (such as diatoms (Fig. 3)), others have tail like appendages called flagella that allow them to swim (Fig. 1) and some species have small air sacs (called vesicles) that they can inflate to rise through the water column (e.g. some species of cyanobacteria (Fig. 4))1. The diversity in phytoplankton adaptations means that different species dominate under different conditions3. This, along with their fast growth rates means that phytoplankton are good indicators of changes in climate, extreme events or human impacts such as pollution within lake ecosystems1,4. As a result of this, algal communities are monitored in conjunction with other chemical and ecological variables to determine the water quality status of lakes3.

Figure 1 Trachelomonas sp. from Belham Tarn, UK (Photo credit: Emma Gray)
Figure 2 Pediastrum sp. from Belham Tarn, UK (Photo credit: Emma Gray)
Figure 3 Asterionella sp. from Belham Tarn, UK (Photo credit: Emma Gray)
Figure 4 Dolichospermum sp. from Belham Tarn, UK (Photo credit: Emma Gray)

My previous research has focused on the impacts of changing climate and weather events on the surface mixing of lakes and the consequences of this for phytoplankton communities. The depth of surface mixing controls the light and nutrient availability phytoplankton are exposed to. Shallow mixed layers are typically occupied by buoyant or motile phytoplankton as taxa that rely on mixing to keep them entrained tend to sink out of shallow mixed layers. With climate change, the surface water temperatures of many lakes are increasing1 which may lead to shallower surface mixing. These conditions are thought to promote blooms of cyanobacteria which can reduce water quality6.  Quantifying the depth of surface mixing from observed data is difficult as there is no universal method or consistent definition of the mixed depth which has consequences when trying to analyse the impact of mixing on phytoplankton as I explored in this research paper. Mixing can also be simulated using models to test different scenarios. Using the phytoplankton model PROTECH we found that shallow mixed layers and warmer water temperatures led to the dominance of the buoyant cyanobacteria Dolichospermum sp. (Fig. 4) and deeper mixed layers led to the dominance of low light adapted cyanobacteria Planktothrix sp  which may have negative impacts on water quality (full paper here).

As part of the PeAT Lakes project, we will be sampling not only the free-floating algae (phytoplankton) but also algae (benthic diatoms) that live of the surface of substrates such as rocks and those that are attached to plants (epilithic algae, typically desmids (Fig 5)). We will use information such as species community composition and diversity to help develop reference conditions for our two lake types (oligotrophic isoetid (3110) and dystrophic lakes (3160)) in Ireland. I am looking forward to getting back behind the microscope and getting to know the algal communities of these lake types.

Keep up-to-date with Emma’s research @PeAT_Lakes

References

  1. Reynolds, C. S. (2006). The ecology of phytoplankton. Cambridge University Press.
  2. Naselli-Flores, L., Zohary, T., & Padisák, J. (2020). Life in suspension and its impact on phytoplankton morphology: an homage to Colin S. Reynolds. Hydrobiologia, 1-24.
  3. Kruk, C., Devercelli, M., & Huszar, V. L. (2020). Reynolds Functional Groups: a trait-based pathway from patterns to predictions. Hydrobiologia, 1-17.
  4. Padisak, J., Borics, G., Grigorszky, I., & Soroczki-Pinter, E. (2006). Use of phytoplankton assemblages for monitoring ecological status of lakes within the Water Framework Directive: the assemblage index. Hydrobiologia553(1), 1-14.
  5. O’Reilly, C. M., Sharma, S., Gray, D. K., Hampton, S. E., Read, J. S., Rowley, R. J., … & Weyhenmeyer, G. A. (2015). Rapid and highly variable warming of lake surface waters around the globe. Geophysical Research Letters42(24), 10-773.
  6. Paerl, H. W., & Huisman, J. (2008). Blooms like it hot. Science320(5872), 57-58.