Monitoring macroinvertebrates and diatom populations in East Stoke, Dorset

As part of a long term, collaborative research project between BU and the FBA, PhD researcher Tadhg Carrol and BU research assistant Jack Dazley have been assisting freshwater biologist John Davy-Bowker in sampling two rivers in East Stoke, Dorset for aquatic macroinvertebrates (such as insect larvae, aquatic worms and water beetles) and diatoms (microscopic plants with a glass-like ‘shell’). The research aims to understand how environmental changes, such as increased temperature and altered riverbed composition, affect the abundance and species diversity of these groups.

Samples were collected from 5 sites at each river – the Frome and the Piddle, where a square sampling area 10m wide was set up from each bank. Macroinvertebrates were collected using the kick sampling method (pictured), whereby the person sampling would rigorously kick the river bed, exposing mud and stones, and with them the invertebrates, which flow into the net. Environmental measurements were also taken, and included width and depth of the site, percentage cover of each species of aquatic plant, and substrate composition of the riverbed (i.e. what types of rocks/stones are present). Once collected, the samples were preserved to allow identification at a later date.

Diatoms were also collected from each site, and were done so by collecting 5 large stones (one from each corner of the site and one from the centre) which had clearly visible signs of algae growing on them, such as green mats on the surface. Using a toothbrush, a section of the green mat was scrubbed off into a plastic tray to collect the diatoms, and to work out the abundance the scrubbed area was traced onto acetate. The diatoms were preserved to be analysed at the lab.

Alongside collecting macroinvertebrates and diatoms, careful note was taken in the Piddle upon the capture and rerelease of protected species, including bullhead fish and white clawed crayfish. These native crayfish are particularly monitored as they are susceptible to diseases carried by the non-native signal crayfish. Infact, the Piddle is thought to be one of the only sites in Dorset where the white clawed crayfish is relatively abundant.

This project is incredibly important to understanding the future of river communities from a bottom up perspective – diatoms and macroinvertebrates form the basis of the food chain in river ecosystems, and so support larger freshwater organisms such as fish and birds.

Lake Oleiden: A Biodiversity Hotspot in Kenya

Whilst in Kenya, one project that the team was carrying out was an ecological survey of freshwater microbes in several different locations across Kenya, and whether the diversity of microbes correlated at all with the diversity of animals species seen. One such location which was sampled was Lake Oleiden, which proved to be a hotspot for wildlife.

Lake Oleiden is located next to the much larger Lake Naivasha, from which it has recently separated, and is slightly saline in nature. The lakes are home to many fish species, a whole host of water birds, and hippopotamus. The water samples collected showed that the lake is rich in phytoplankton (microscopic plants) and many species of flagellates, tiny single-celled organisms which use a tail-like appendage called a flagellum to move around in the water. Flagellates and phytoplankton are important sources of food for tiny invertebrates such as water fleas and copepods, which are in turn eaten by small fish.

Just a small sample of the waterbird species seen: great white pelican, pink-backed pelican, long-tailed cormorant and great cormorant

As a result, there was an incredible diversity of fish-eating bird species, with over 10 different species of bird seen on the lake. There were two species of cormorant seen, and they had established several nesting sites at the banks of the lake, supporting one of the largest congregations of these birds in the country, according to our local guide. Also present were several flocks of great white pelican (pictured within a multi-species community with cormorants and gulls), which were seen feeding alongside terns, gulls and a pair of pied kingfisher, which we were lucky enough to see hunting for fish. At the shore of the lake were a variety of herons and storks including the little egret, marabou stork, yellow-billed stork and the black heron, which has an ingenious hunting strategy, using its wings as shade, attracting fish for it to catch. The lake is also home to the impressive African fish eagles, seen swooping to catch fish from the water’s surface.

This great diversity can be sourced back to the microbes. They provide food for tiny invertebrates which are in turn consumed by the fish in the lake. And of course it is the fish which attract the birds to the area, promising a rich source of food, and by extension, a suitable breeding ground for several species.

Biodome carnivorous plants reveal hidden microbial diversity

Some carnivorous plants hold ‘pools’ within the plant consisting of rainwater and secreted substances such as sugars, used to lure and trap insect prey. Microscopic analysis of this fluid collected from pitcher plants (Sarracenia sp.) and bromeliads (Brocchinia sp.) growing in BU’s Biodome has revealed a rich diversity of single-celled microorganisms. These microbes, less than half a millimetre in length, are known as ciliates and distinguished by hair-like cilia that they use for locomotion and feeding.

Ciliates are incredibly important grazers, feeding on bacteria, algae and organic matter, and are a crucial part of the microecosystem within the bromeliad and pitcher plant pools, which also includes algae, bacteria and insect larvae, such as mosquitoes. In turn, they are also fed upon by mosquito larvae and copepods that also grow in such pools, playing an important role in energy transfer from microbes to animals.

One of the microbes found within the pools was the ciliate Euplotes, pictured above. © J.Dazley
Exploring Plankton Diversity in Southampton Water

Exploring Plankton Diversity in Southampton Water

Undergraduate students in the department of Life and Environmental Sciences investigated the diversity of phytoplankton and zooplankton in Southampton water as part of their third-year Biological Oceanography module. Using the research vessel RV Callista at the National Oceanography Centre Southampton (NOCS), samples were collected at 5 locations, or “stations”, between Calshott and the Itchen River.

Environmental data was collected at each station using an array of sensors, measuring parameters such as temperature, salinity, chlorophyll and oxygen concentration. Phytoplankton were collected at two depths at each site, representing deep and shallow water. Zooplankton was caught using a plankton net, with a 120µm mesh to catch zooplankton in the net. These samples were subsequently analysed back at the university.

Trawls and grab samples were also used to investigate the benthic (bottom dwelling) communities living on the seabed and to analyse the oxygen content of the sediment. Benthic animals found included starfish, fish such as gobies and flounders, cuttlefish, crabs and ‘moss animals’ (bryozoans).

Back at BU, the phyto- and zooplankton samples were analysed using microscopy. A variety of diatoms and dinoflagellates were found in the phytoplankton samples, and barnacle larvae, copepods and the larvae of marine worms were found in the zooplankton samples. Microbes too small to be seen under the microscope were counted using flow cytometry, a technique used to identify cyanobacteria and other minute cells.

The study demonstrated the great diversity of planktonic and benthic life in Southampton water, and highlighted the importance of monitoring and understanding the microscopic life of the sea since the microscopic life , as the base of the food web, is crucial in sustaining the larger and better understood forms of marine life.

Saving Europe’s Crickets and Grasshoppers From Extinction

A recent assessment of cricket and grasshopper species in Europe has shown that up to 25% are facing extinction. According to the International Union for Conservation of Nature (IUCN), the group Orthoptera, which includes Grasshoppers, Crickets and Bush Crickets, is the most threatened group assessed so far. An estimated 1000 species of Crickets and Grasshoppers are found in Europe. They play a vital role in grassland ecosystems; many species of birds and reptiles feed on them. The main factor contributing to decline is habitat loss due to wildfires, tourism and intensive farming. Many species are confined to small areas due to the break up of their natural habitats; for example the Crau Plain Grasshopper has been confined to the steppes on Southern France.

So what can be done in order to protect these insects? According to research from the IUCN Global Species Programme, more effort must be put into restoring the habitats of these insects in order to increase population size. This can be achieved using sustainable grassland management by employing traditional agricultural practices. It is imperative that these insects are saved from extinction, not only because they are very important biodiversity indicators, but also they are an integral part of grassland ecosystems.

Image Credit: Axel Hochkirch

Bittern Numbers Booming In The UK

The Common Bittern, Botaurus stellaris, a shy, secretive relative of the heron, was once extinct in the UK, however the bird has made a massive comeback over the years. Bittern numbers are now at their highest recorded numbers in the UK.

The bittern lives mostly in reed beds and is rarely seen due to the superbly camouflaged streaked plumage, which blends perfectly with the environment. However, the male’s booming call can be used to identify the presence of bitterns, and so researchers have been able to count these birds.

This year, the breeding population has been at it’s highest since the 1800s, with 140 singing males seen, compared to 11 in 1997. Somerset has the largest bittern population, with 20 males located at Ham Wall nature reserve,

According to the RSPB, one factor contributing to UK population increase in bitterns is due to restoration of quarries, which has helped bitterns to thrive. The bittern is still on the RSPB’s red list, but the development of these restored quarries is expected to increase the UK’S bittern population in the future.

Image credit: Helen Briggs

Restoration of Native Flora Encourages Bird and Insect Pollinators

Scientists investigating the effect of exotic plant species on native plant biodiversity on the island of Mahe in the Seychelles have found that ecosystem restoration by removal of exotic plant species is linked to an increase number of pollinating species such as bees, butterflies and birds and an increase in flowering of native flora.

Eight study sites on Mahe’s mountains were monitored for a period of eight months, with non-native plant species being removed from four sites. Native plant species were found to be flowering more frequently and attracting more pollinators. An increase in the number of pollinator species was also observed 6-12 months after the removal of exotic species, including bees, wasps, flies, beetles, moths, birds and lizards.

The research from Mahe mountaintops gives us a clear demonstration of the role of ecosystem restoration in pollination and interaction between plants and animals, and that ecosystem degradation is, at least partially, a reversible process.

Picture credit: C. KAISER-BUNBURY