Sediment Mobility of Maerl Modelling Study

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Maerl biogenic gravel beach at Carraroe, County Galway

ResearchBlogging.orgOur new study on “Mobility of maerl-siliciclastic mixtures: impact of waves, currents and storm events,” has just been published (in press) in Estuarine, Coastal and Shelf Science. This is the final part of my PhD in maerl sediment dynamics. Sediment mobility in its simplest form is the percentage of time grains of a particular size are mobile during  a tidal cycle (Idier et.al., 2010). This study focuses on the sediment mobility of maerl in particular, utilising coupled hydrodynamic-wave-sediment transport models to model the oceanography during calm and storm conditions and the resulting sediment transport. Sediment mobility models are another way of quantifying the disturbance of the seafloor as a result of currents, waves and combined wave-currents. This study calculates two sediment mobility indices, the Mobilization Frequency Index (MFI) and the Sediment Mobility Index (SMI), related to the magnitude and frequency of disturbance events (Li et.al, 2015). The residual currents, which are the part of the current remaining after removing the oscillatory tidal component, show that maerl prefers intermediate mobility environments and is often found at the periphery of the residual current gyres. Sediment mobility maps can be used to inform marine spatial planning for the management of both live and dead (fossil) maerl beds, as a result of climate change or anthropogenic activity.

The full research paper, Joshi et.al. 2017, can be found here.

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References

Idier, D., Romieu, E., Pedreros, R., & Oliveros, C. (2010). A simple method to analyse non-cohesive sediment mobility in coastal environment Continental Shelf Research, 30(3-4), 365-377 DOI: 10.1016/j.csr.2009.12.006

Joshi, S., Duffy, G., & Brown, C. (2017). Mobility of maerl-siliciclastic mixtures: Impact of waves, currents and storm events Estuarine, Coastal and Shelf Science DOI: 10.1016/j.ecss.2017.03.018

Li, M., Hannah, C., Perrie, W., Tang, C., Prescott, R., Greenberg, D., & Rygel, M. (2015). Modelling seabed shear stress, sediment mobility, and sediment transport in the Bay of Fundy Canadian Journal of Earth Sciences, 52 (9), 757-775 DOI:10.1139/cjes-2014-0211

Mangroves of Pichavaram

It had been a dream of mine to see the mangroves since learning about their importance in coastal defence in my lectures and blogging about them. This winter my family and I had the brilliant opportunity to go to the Tamil Nadu Backwaters to see the mangroves of the east coast of south India- at Pichavaram.

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“Pichavaram is known for its unique mangrove ecosystem, found in areas such as the Sunder bans in West Bengal and in Australia. The mangroves are trees rooted in a few feet of water and the whole area stretches to over 3,000 acres comprising more than 1,700 islets. Pichavaram consists of a number of islands interspersing a vast expanse of water and covered with green trees. The area is about 2800 acres and is separated from the sea by a sand bar, which is a patch of extraordinary loveliness. To a botanist, rare species like Avicennia and Rhizophora will present a special attraction; to a zoologist, no doubt, the sight of numerous birds like Water snipes, Cormorants, Egrets, Storks, Herons, Spoonbills and Pelicans holds great interest. Of around eighty species worldwide, Pichavaram is home to 14 species, chief among them being Avicennia and Rhizophoro. The Pichavaram swamps are one of the healthiest occurrences in the world, and act as a nursery for a variety of finfish and shell fish. They also effectively demonstrated their role as a bio-shield in the recent Indian Ocean Tsunami; there was no loss of life in communities living next to the mangroves.” (Tamil Nadu Tourism)
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We also took the opportunity to visit the Centre of Advanced Study in Marine Biology of Annamalai University, where they very kindly offered us a tour of their centre. The centre has a fascinating zoology museum and a long history of training over 600 PhD students as well as study of the mangroves and also deep sea organisms off the Indian coast.

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A wonderful experience- a special thank you to my family and the Annamalai university for the tour!

 

Book Review: Rhodolith/Maërl Beds: A Global Perspective

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This new book on Rhodolith/Maërl Beds* has been much anticipated by the rhodolith research community. With over four years in the making, it is a volume tributed to Prof. Rafael Riosmena-Rodríguez, who dedicated 25 years particularly to the study of the taxonony of coralline algae and sadly passed away earlier this year. Prof. Riosmena-Rodríguez will be very much missed by the rhodolith research community and this book is an important tribute.

The book begins with the role of rhodolith/maërl beds in modern oceans, with chapters on natural history and biodiversity around maërl beds, rhodoliths as climatic archives, modern day threats of ocean acidification on maërl and economic importance. The role of rhodolith in historical oceans and the geological significance is explored by the following section, with a particular focus on the Mediterranean area as well as the North Atlantic sedimentary dynamics. The final part of the book covers the conservation status of rhodoliths globally and serves to be an important summary of current state of regional knowledge of rhodoliths in the major geographic areas.

“These marine beds occur worldwide, from the tropics to the poles, ranging in depth from intertidal to deep subtidal habitats and they are also represented in extensive fossil deposits.”

Overall, this is a much needed edition for marine biology libraries around the world and highly recommended for students of one of the four macrophyte dominated benthic communities. I made a blog post about attending the International Rhodolith Workshop in Granada and one of the key conclusions of the 2015 workshop in Costa Rica was that international recognition is needed for rhodolith habitats to ensure their protection. This book is an important step required to make this possible. It serves to be a useful and comprehensive introduction summarizing the multidisciplinary study of global rhodoliths/maërl beds.

*The term maerl originally refers to the branched growth form of Lemoine (1910) and the term rhodolith is sedimentalogical or genetic term for both the nodular and branched growth forms (Basso et. al, 2015).

Reference

Basso (2015) Monitoring deep Mediterranean rhodolith beds. Aquatic Conservation Marine and Freshwater Ecosystems. 26:3. doi:10.1002/aqc.2586.

Lemoine (1910) Répartition et mode de vie du maërl (Lithothamnium calcareum) aux environs de Concarneau (Finistère). Annales de l’Institut Océanographique. 1: 1–29.

Riosmena-Rodríguez, R., Nelson, W., and Aguirre, J. (Editors) (2016) Rhodolith/Maërl Beds: A Global Perspective, Coastal Research Library 15, VIII, 368pp.DOI: 10.1007/978-3-319-29315-8

 

Before the Flood

“Before The Flood is the product of an incredible three-year journey that took place with my co-creator and director Fisher Stevens. We went to every corner of the globe to document the devastating impacts of climate change and questioned humanity’s ability to reverse what may be the most catastrophic problem mankind has ever faced. There was a lot to take on. All that we witnessed on this journey shows us that our world’s climate is incredibly interconnected and that it is at urgent breaking point.”

-Leonardo DiCaprio, UN Messenger of Peace on Climate Change (Source: Wikipedia)

Watch the full film “Before the Flood” on YouTube till 6th November.

Life Below Water: Sustainable Development Goal 14

What are the Sustainable Development Goals?

ResearchBlogging.org

The Sustainable Development Goals (SDGs) are an intergovernmental set of aspiration Goals with 169 targets. The Official Agenda for Sustainable Development outlined 17 Sustainable Development Goals and its associated 169 targets to be achieved by 2030. It all started when I recently attended the Mary Robinson SDG Symposium in Ballina, County Mayo. This covered detailed discussions of SDG 5- Gender Equality, SDG 10- Reducing Inequalities and SDG 16- Peace. For the first time the UN has included a Sustainable Development Goal about the oceans in its new sustainable development agenda. We have a very special interview from Andrew Hudson, Head of Water & Ocean Governance, UNDP  about the Sustainable Development Goal 14 on the oceans (Life below Water) and Sustainable Development Goal 6 on water (Clean water and sanitation).

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1) Why are the oceans important to our planet and what are the main threats or challenges affecting it?

Andrew Hudson: “The oceans cover over 70% of the planet and represent over 99% of the earth’s living space.  They provide food security for billions, are the major transport hub on earth for traded goods (via shipping), are probably the single most sought after tourism amenity, produce half the world’s oxygen. Oceans are the major regulator of the earth’s climate through their absorption and release of heat energy, absorbing some 87% of the extra energy that greenhouse gases create in the atmosphere and 30% of the anthropogenic CO2 we emit. The ocean economy – shipping, fishing, aquaculture, oil and gas extraction, tourism – is valued at several trillion dollars per year, and that is only for the marketized benefits, it doesn’t include the immense non-market benefits the ocean provides such as climate regulation.

The principal five threats to a sustainable oceans are: overfishing, coastal habitat loss (corals, seagrass, mangroves, etc.), pollution (especially by nutrients and plastics), invasive species (especially those carried in ship’s ballast water and on hulls) and ocean acidification (since the 30% of anthropogenic CO2 that dissolves in oceans creates carbonic acid, lowering the pH/increasing the acidity of the oceans).”

2) For the first time the UN has included a Sustainable Development Goal about the oceans in its new sustainable development agenda. What are the SDGs and in particular Goal 14: Life below water and Goal 6: Water?

Andrew Hudson: “SDGs 6 (water) and 14 (oceans) are in many ways complementary.  SDG6 sets ambitious targets such as universal access to clean water and sanitation services, dramatically increasing the treatment of wastewater, improving water use efficiency, and protecting freshwater ecosystems.  SDG6 and 14 calls for reducing marine pollution, protecting coastal ecosystems, ending overfishing including elimination of destructive fisheries subsidies, achieving 10% of the oceans under marine protected areas, improving resource and market access for small scale fishers, and enhancing ocean economic benefits to the poorest people and those who live in Small Island Developing States (SIDS).”

SDG143) What is the role of the UNDP Ocean Governance programme in implementing the SDGs Goals 6 and 14?

Andrew Hudson: “Through its Ocean Governance Programme, UNDP is working with other UN agencies, the Global Environment Facility, international financial institutions, regional fisheries organizations and others to improve ocean management and to sustain livelihoods at the local, national, regional and global scales through effective ocean governance. UNDP’s Ocean Governance Programme is strongly aligned with Sustainable Development Goal (SDG) 14 on Oceans – Conserve and sustainably use the oceans, seas and marine resources for sustainable development. The active portfolio and pipeline of UNDP projects and programmes support the majority of SDG14 targets. We support the creation of an enabling policy environment for ocean restoration and protection through the development of ocean and coastal management strategic planning tools and methodologies.  We support the codification and application of the Global Environment Facility’s (GEF) Transboundary Diagnostic Analysis/Strategic Action Programme planning approach to address aquatic ecosystem degradation at the scale of Large Marine Ecosystems (LME). We also promote bottom-up approaches to maintaining aquatic ecosystem services at smaller planning scales (municipalities, provinces, local watersheds) – Integrated Coastal Management (ICM) and Integrated Water Resources Management (IWRM). We help build upon and advance existing or anticipated regional or global multilateral agreements to address threats to large-scale ocean sustainability such as from shipping and highly migratory tuna stocks. We support countries in the creation of new Marine Protected Areas (MPA) and the strengthening of existing MPAs through the UNDP Ecosystems and Biodiversity programme.”

Continue reading “Life Below Water: Sustainable Development Goal 14”