Marine Ecology Research
Time for a presentatie for WWF, TNC and the local goverment in Berau about our research in Derawan. After a morning with presentations (Nina thanks for the translation in Bahasa Indonesia) and a very nice discussion it was time for a afternoon of jungle. We rented a boat and drove 0,5 hours from Berau to a small river where it was seeming with monkeys. The “Orang Belanda” Proboscis monkey was there and 4 other species. Not al pictures are sharp but more for the archives 🙂
Two months into my first research period I would like to update you on my progress. Because it’s almost impossible to post from my research location on Derawan I will show a compilation of photo’s. When I will be back in the Netherlands I will elaborate some more on the specific experiments. Click on the photo for all the research photo’s.
In the first week at Derawan I saw so many turtles, therefore a post about the “production of new turtles”. Yesterday night I saw 4 turtles (Chelonia mydas) crawling on the beach to search for a suitable site to lay their eggs above the high tide line.
She digged out a large hole in the surface of the beach using a swimming movement of her front flippers, creating the “body pit”. After ten minutes or more, actively throwing sand behind her, she beginned digging with her hind limbs, excavating the egg chamber of about 60 cm deep. Without pausing she continued laying 90 ‘ping-pong-sized-eggs’ (While the eggs are being deposited into the egg chamber, they can tolerate bouncing, rolling, tumbling or handling, but about two hours after being laid, the embryo will resume development, and may be killed by a simple roll of the egg.) Ferry from the WWF digged up the eggs to protect them from poachers. Now we have to wait 45-70 days for the small Tukik (turtle hatchling in Bahasa Indonesia) to hatch. Higher temperatures produce more females and result in shorter incubation periods. At Derawan Ferry will check development of the nests so that he can digg the eggs out and release the small flippering friends before poachers or predators find them.
After nesting, the female went back to the coral reef to rest and complete the next clutch of eggs. They are known to mainly rely on their stored fat reserved while resting and completing the next clutch of eggs. She can lay several clutches of eggs at approximately two-week intervals before finally migrating back to her feeding ground. We are still in doubt if the mother turtles are the same ones grazing on the seagrass fields in front of Derawan at daytime, or if they only visit this Island to lay their eggs and travel back to their feeding ground.
Before my supervisors arrive and the experiment will be started I’m first testing my cage set-up. The cages are build out of concrete-iron with fishing nets on the sides and on top of the cage, attached by cable ties. The net is 5cm in diameter to prevent the turtles from getting stuck into the net. Within the cage I’ve tested the best way to sample, harvest and count the seagrass shoots. And also tested how long it takes for the seagrass leaves to grow back. The locals are very interested in the strange things that I’m doing underwater so it’s never boring. I’m leaving to Balikpapan know to pick up my supervisors and check the seagrass in Balikpapan bay and after that the experiment can start. Finally! Click on the photo for more pictures.
The first days I’m testing the set-up of my experiment, I’m snorkeling 4 hours a day to check out the seagrass and the turtles here (also found dugong grazing trails!), and I’m talking to officials here and setting up logistics at this island. The 21th of May my supervisors and students are arriving so I will travel back to Balikpapan to pick them up and do some measurements at Balikpapan bay.
At this moment I’m staying at Derawan Beach Cafe. It’s a convenient place with very kind people, good food (with vegetables, and nasi goreng as breakfast) 24hrs power, airco and a toilet to sit on. The only question is if I can stay here until september because the 300.000rp per night.
Together with Liesbeth Pierson we spend a day looking to seagrasses at a totally different perspective. The results from 6 tropical seagrass species are published at vitual classroom biology but you can get sneak preview of microscopic views of Cymodocea serrulata below.
In this movie you can see the transport of chloroplasts over a cytoplasmatic strand.
Without revealing to many details, I show you some pictures about my first experiment of my Phd project. Together with Tjisse I’m looking (amongst others) at the effect of ammonium on Thalassia hemprichii under high and low light conditions. Here are some pictures of the experimental set-up:
A detail of on of the 40 shoots of T. hemprichii the rhizome is cut to 3 cm and a stainless steel nut is connected to the shoot to keep it on the bottom of the glass collumn.
The first results of the PAM measurements on photosynthesis are very promissing! Unfortunately the preparations of my field campaign to Derawan is more pressing at the moment, so analysis has to wait.
And now lets hope that the rest of the imported seagrass from Indonesia will survive and grow new shoots for the next experiment. Here are some tips on growing seagrass in aquaria.
Newspaper DAG (11-12-2007) followed me during the experiment:
To get permission to do my fieldwork in Indonesia I’m trying hard to get al the required documents together. These are all the documents that you need to apply for a research permit.
Seagrass systems under nutrient loads and grazing. Interactive effects and feedbacks. 5 year PhD project within the NWO-WOTRO project WT 84-645
MJA (Marjolijn) Christianen MSc.
Description of the project
Rapidly growing economic development in SE Asia has led to increased human activities, particularly in coastal areas (L. Kamp-Nielsen et al. 2002). Among others, deforestation, fish and shrimp culturing and increasing inhabitation results in strongly increased nutrient and sediment loads to coastal waters, which threaten the economically and ecologically important seagrass beds, and have caused their almost complete disappearance in many areas (FT Short et al. 1996, R Constanza et al. 1997, A Balmford et al 2002). We hypothesise that seagrass systems are characterised by strong positive and negative feedbacks, which make them liable to sudden and irreversible state transitions. Based on existing knowledge and pilot studies, our main overriding hypothesis is that nutrient load, sediment load, hydrodynamics and grazing on the seagrass are the most important drivers that push the seagrass ecosystem into different functional states (figure 1). Our research is directed towards testing this hypothesis, and understanding the basic feedbacks. This is of great scientific importance, and has important implications for practical management. Within the present proposal, we focus on the interaction between nutrient loads, changes in transparency and grazing for the productivity and health status of seagrass beds.
Figure 1. Schematic representation on how seagrass meadows may degrade in response to land-use, and which shifts are easy/difficult to reverse.
Results in the literature show that in relatively oligotrophic waters subject to increased nutrient and sediment loads, complex interactions between (stoichiometry of) nutrient additions and sediment enrichment govern the growth and dynamics of seagrass.
We propose to test the hypotheses that (1) direct toxicity of nitrogen to seagrass occurs at environmentally relevant concentrations in tropical seagrass beds; a positive feedback may arise because increased toxicity decreases growth rate, and thus increases vulnerability to nitrogen loads.; (2) strong grazing may protect seagrass meadows from overgrowth by epiphytes, increasing critical loads; (3) under increased organic loading of the sediment, iron deficiency may push the system in a state of increased sulphate reduction, a positive feedback may arise through sulphide toxicity effects and decreased aeration of the rhizosphere.
In East-Kalimantan, at 4 seagrass sites representing different conditions of the system, we will perform a field survey to measure indicators of the actual seagrass states and relevant environmental variables (used in all 3 hypotheses). Controlled mesocosm experiments will be performed in the Netherlands with different concentrations of nitrogen under varying growth-limiting conditions (hypothesis 1). In East-Kalimantan, at low and intermediately eutrophicated sites we will manipulate grazing and nutrient supply (hypothesis 2), and vary organic loading and iron supply (hypothesis 3). At sites where seagrasses have disappeared we will perform a transplantation experiment and test the effect of iron additions (hypothesis 3). Additional to the valuation of our hypotheses, our results will provide nutrient thresholds for shifts that can be used in modelling, and an assessment of the restoration possibilities in heavily disturbed areas
Figure 2. Locations of field research within the Berau Delta, East-Kalimantan, Indonesia.
Research locations
The research in The Netherlands will be carried out at the Radboud University Nijmegen at the Institute for Wetland and Wetland Research and at the Netherlands institute for Ecology in Yrseke at the department of Spatial Ecology, in close coorperation with the Research Centre for Oceanography of the Indonesian Istitute of Sciences (LIPI). The fieldwork will be carried out in Indonesia, where studies will be conducted at locations with varying degrees of nutrient and sediment loading (Figure 2). The fieldwork is focussed on the Berau delta in East Kalimantan cluster. The Berau delta forms a watershed with very low logging intensity in the upper watershed, good forest cover and a very low level of mining operations. Mangroves in the Berau delta are still largely intact.
Other participants
Dr. M.M. van Katwijk Dept. of Environmental Studies RU Nijmegen
Prof.Dr. J.G.M. Roelofs* Dept. of Environmental Biology RU Nijmegen
Dr. L.P.M. Lamers Dept. of Environmental Biology RU Nijmegen
Dr. S. Wouthuyzen Res. Center for Oceanography LIPI
Dr. M. Hutomo Res. Center for Oceanography LIPI
Dr. T.J. Bouma Dept. of Spatial Ecology NIOO-CEME – Yerseke
Prof. Dr. P. Herman* Dept. of Spatial Ecology NIOO-CEME – Yerseke
*Promotores
Here you can find the complete proposal