The WSA website and blog were hacked in mid-January and although no data was lost nor was there any confidential information at risk it caused a bit of a mess. The blog has been reinstated and the main site has been rebuilt from scratch.


Every so often (but only as often as we receive contributions) we feature a seagrass meadow from around the world. This week, Laura Soissons shares her observations of her field site in the Yellow River Delta in China. Laura is a PhD student with the Royal Netherlands Institute for Sea Research (NIOZ-Yerseke) studying human impacts on seagrass.


Photos & text by Laura Soissons

“Where are the seagrasses?” This is the main question my colleagues and I had in mind last summer when we were visiting our field site in the Yellow River Delta area in China. Sadly enough, we haven’t seen them make a comeback.

Seagrasses in the Yellow River Delta are the main topic of a collaborative project between the Royal Netherlands Institute for Sea Research (NIOZ-Yerseke) and the Yantai Institute for Coastal Zone Research (YIC-CAS) in China founded by the NSFC-NWO. As part of this project, my PhD research is, in a broad perspective, looking at the impact of human activities on seagrasses and how these activities can affect their resilience to environmental stresses. Our first and main focus is to understand the recent seagrass decline in the Yellow River Delta area.

And this is where the story starts…

When we first visited the area in 2011, we found a small and declining seagrass meadow southward of the Yellow river mouth, surrounded by dikes, oil platforms and salt industries. We called it: YR5.

Pumpjacks, oil platforms and salt evaporation ponds on the coastline surrounding the seagrass meadow


The meadow was composed of a single seagrass species: Zostera japonica and showed a sparse and poor distribution over the tidal flat.

One patch of the Zostera japonica meadow in May 2011 at YR5


We progressively learnt about the recent dike construction around the area that cut kilometres of the tidal flat, and thus changed the whole shape of the area. We also discovered some interesting and dominant species like the snail Bullacta exarata, which is invading the entire area and used for aquaculture. Further research on this snail showed us that it originates from Korea and arrived in the area in 2008 after being placed and cultured there by humans for food. It mainly feeds on diatoms and organic matter at the sediment surface but not on seagrasses. Nevertheless, this species is now colonizing the entire tidal flat and remains one of the last living species there (together with crabs and a few bivalves).

The snail Bullacta exarata (Philippi, 1848) at YR5


Back to the YR5 field site at the end of May 2012, we had hard times finding the seagrasses. After hours of searching we finally found some even scarcer shoots in an area surrounded by the saltmarsh plant Spartina anglica in tussocks (invasive plant in that area). Local temperatures were already high enough to think that the seagrasses were late for the growing season… And when we looked at the shoots in more details, we saw how unhealthy they were: holes in the leaves, black leaves and very weak tissues.

Left over of the seagrass meadow in May 2012 (zoom on seagrass shoots from the same place)

Two weeks after this discovery, we came back to the exact same place. We found only dead rhizomes, and just a couple of shoots left with more black leaves than before. We even felt very guilty for having been sampling a few shoots two weeks before (samples for tissue analysis, trace elements and pollutants content).

June 2012 – dead rhizomes at YR5 as the only remaining of the seagrass meadow

We observed a highly dynamic system over the summer with strong winds and waves at high tide. Sediment was getting coarser and accreting, sometimes burying the seagrass shoots. For our final visit at the end of July, no seagrasses were left. The dead rhizomes were washed away or already degraded and the hours we spent looking for seagrasses remained unsuccessful.

There are many reasons that could explain the sudden collapse of this Zostera japonica meadow at YR5. It could be the anthropogenic influence but also a combination of changing environmental variables and pollution from the Yellow River and surroundings. So far, we found no historical data reporting the existence of this meadow or anything related to the status of this particular tidal flat before the dike construction in 2009 (from what we know). Observing the seagrass meadow decline over its ‘growing season’ showed us one more time how crucial it is to take into account our long-term influence on a meadow. Stakeholders in that area will not give up on expanding their activities but also want to consider their impact and the need to preserve their environment. Within our project we want to emphasize this seagrass loss by understanding more about the reasons of their decline and how we made it happen.

By Brigit van Tussenbroek

Small invertebrates play a central role in seagrass communities as controllers of epiphyton and conduits for energy transfer from primary producers to higher trophic levels. Van Tussenbroek and collaborators at the National Autonomous University of Mexico, highlight a new interaction between meso-grazers and seagrasses by describing the foraging of invertebrates on the pollen/mucilage masses of the seagrass Thalassia testudinum during the night.

Male turtlegrass flower with invertebrate.

The fauna visiting the flowers was highly diverse 252 specimens belonging to 37 families and 57 species of crustaceans (Classes Maxillopoda, Ostracoda and Malacostraca) were found on 76 flowers, and 15 species were new records for the region. Annelids (mainly polychaetes) were less abundant (60 specimens) and diversified (13 species) and they exhibited no obvious differences in their visits to flowers with or without pollen. Negative consequences for reproductive success of the seagrass of the consumption of pollen by the invertebrates were most likely insignificant, because the quantities of removed pollen were very small. However, these invertebrates may serve as pollinators of T. testudinum, which if confirmed, makes this observation the first record of animal-pollination in the marine environment.

Check out the YouTube video

Find the paper in MEPS

It’s been almost two weeks since the end of the 10th International Seagrass Biology Workshop in Búzios, Brazil and I’ve decided to do a blog post before the memories get too fuzzy. Here’s a re-cap of what we did the last three days of the conference:

Day 3: Geting into the swing of things
We started the morning with the third plenary speaker for the Worshop, Sophie Arnoud-Haund who gave us a round-up of the state of seagrass genetics and clonality. She offered insights into clonality and how it affects conservation of seagrass meadows. This was followed by a second day of 10-minute talks with the theme of .
In the afternoon we had two workshop sessions – mapping and ecosystem services. The workshop on mapping discussed and listed the various methods used by researchers and the challenges faced when mapping seagrass – and we learnt of some pretty creative methods used for mapping and detecting seagrass like for example, strapping a camera on the back of a manatee! The second workshop was on seagrass ecosystem services which really got us thinking about the value of seagrasses and the services they provide as it required listing the services of seagrass by genera.

Day 4: Field trip Day & Poster Session
We went out to hunt seagrass on Day 4 and we were brought to a meadow of Halodule wrightii seagrass. When we got to the site, it was windy and threatening to rain, but some of us decided to brave the cold and jump right in. This enthusiasm was perhaps fueled by rumours of a seeker’s prize for the first person to find Ruppia maritima in the meadow, but despite our best efforts, I don’t think anyone managed to find it. Just as we were wrapping up, the sun came out and the weather became more of what we had hoped for for a field trip day.

We also had an evening poster session, with some very simulating discussion aided by a large spread of yummy cheeses and wine 🙂

Day 5: Wrap up and dinner!
Gary Kendrick gave the last plenary of the ISBW and gave us an overview of seagrass dispersal and connectivity. After the last session of talks and workshop, we were rewarded with a conference dinner – a buffet style affair which everyone enjoyed. The student presentation and poster awards were also given out to the top 4 oral and best poster presentation.

And that concluded ISBW10 – there were some bleary-eyed farewells the next morning but in all everyone agreed that it was a successful workshop. Congratulations to Joel Creed and his team for a wonderful job done. See you guys in China in 2014! 🙂


Dear WSA members,

The period for nomination for the next WSA Executive was extended, and closed on the 5 December, 2012.

The positions of Vice-President, Treasurer and Secretary are uncontested with single nominees for each position. The nominations received are as follows:

Vice-President: Richard Unsworth
Nominator: Len McKenzie
Seconder: Giuseppe Di Carlo

Treasurer: Jessie Jarvis
Nominator: Giuseppe Di Carlo
Seconder: Len McKenzie

Secretary: Len McKenzie
Nominator: Rob Coles
Seconder: Rudi Yoshida

There are two nominees for President so this position will be decided by a vote:

Nomination 1

Giuseppe Di Carlo
Nominator: Len McKenzie
Seconder: Richard Unsworth

Nomination 2

Mike van Keulen
Nominator: Anitra Thorhaug
Seconder: Evamaria Koch

Voting is now open but will close on the 19 December, 2012 — so please do not delay in submitting your ballot. Please note that only current financial members of the WSA are allowed to participate in this vote. Members have been emailed directly with instructions on how to cast their ballot, if you have not received instructions about voting please contact the WSA Secretary ASAP < wsa.secretary@gmail.com >.

« Newer Posts - Older Posts »