New SDM paper out!

A new research paper by Charlène Guillaumot et al. “Broad-scale species distribution models applied to data-poor areas” has just been published in Progress in Oceanography. The paper specifically addresses Species Distribution Models, as they have been increasingly used over the past decades to characterise the spatial distribution and the ecological niche of various taxa. Validating predicted species distribution is important, especially when producing broad-scale models (i.e. at continental or oceanic scale) based on limited and spatially aggregated presence-only records. In the present study, several model calibration methods are compared and guidelines are provided to perform relevant SDMs using a Southern Ocean marine species, the starfish Odontaster validus Koehler, 1906, as a case study. The effect of the spatial aggregation of presence-only records on modelling performance is evaluated and the relevance of a target-background sampling procedure to correct for this effect is assessed. The accuracy of model validation is estimated using k-fold random and spatial cross- validation procedures. Finally, we evaluate the relevance of the Multivariate Environmental Similarity Surface (MESS) index to identify areas in which SDMs accurately interpolate and conversely, areas in which models extrapolate outside the environmental range of occurrence records. Results show that the random cross-validation procedure (i.e. a widely applied method, for which training
and test records are randomly selected in space) tends to over-estimate model performance when applied to spatially aggregated datasets. Spatial cross-validation procedures can compensate for this over-estimation effect but different spatial cross-validation procedures must be tested for their ability to reduce over-fitting while providing relevant validation scores. Model predictions show that SDM generalisation is limited when working with aggregated datasets at broad spatial scale. The MESS index calculated in our case study show that over half of the predicted area is highly uncertain due to extrapolation. Our work provides methodological guidelines to generate accurate model assessments at broad spatial scale when using limited and aggregated presence-only datasets. We highlight the importance of taking into account the presence of spatial aggregation in species records and using non-random cross-validation procedures. Evaluating the best calibration procedures and correcting for spatial biases should be considered ahead the modelling exercise to improve modelling relevance.

The full paper can be found here.

Hot off the press: new paper by Antonio Agüera

A new paper was published in MEPS by Antonio Agüera. the article focuses on the crown-of-thorns sea star. The paper is available in open access.

Here’s the abstract:

The crown-of-thorns starfish (COTS), Acanthaster cf. solaris, is an iconic keystone predator whose population outbreaks have devastating consequences for Indo-Pacific coral reefs. We tested the effects of algal food supply and larval density on the frequency of larval cloning by culturing the early bipinnaria larvae of COTS under variable conditions. Here we show that larval COTS are able to clone themselves in both low and high food conditions, and that the frequency of larval cloning increases with levels of food, but is unaffected by larval density. Across all density treatments (0.3, 1.0 and 3.0 larvae ml−1), the per-capita rate of cloning increased from 4.3% in low, oligotrophic conditions (0.17 μg chl a l−1) to 7.9% in high food conditions (1.7 μg chl a l−1). Larval cloning has the potential to increase both COTS larval supply and the dispersal distance of plank- tonic larval stages, both of which are critical factors in predicting the timing and location of out- breaks of this species. In addition, the relationship between algal food supply and larval cloning frequency lends support to bottom-up hypotheses (e.g. nutrient enrichment) as predictors of COTS outbreaks. Howe

New GBIF dataset published

In the framework of the marine biology field work organised by the lab, we will be publishing raw biodiversity data on a yearly basis on the Global Biodiversity Information Facility (GBIF). This dataset is the result of census exercises made by the participating students. The data includes occurrence from the intertidal zone, taken on a yearly basis (by different batches of students), for which identifications are systematically checked by the supervisors. The field work focuses on transects chosen in the the Bay of Wimereux (Pas-de-Calais, France) which are oriented towards contrasted ecological gradients.

You can find more about the dataset here.

 

Launch of the Belgica 121 crowdfunding campaign!

Marking the 121st anniversary since the first Antarctic expedition in human history, an international team of nine scientists embarks on a journey to the frozen continent. Our choice of transport: a small sail boat.

We are launching a crowdfunding campaign to support the  preparation of a documentary about this extraordinary adventure. This documentary is an intimate account of a small group of ambitious individuals, who are passionate about introducing a more sustainable way of conducting Polar research to the science community. The harsh beauty of the Antarctic landscape is reflected in the rawness of the footage, which will be captured by the scientists themselves – above and below water. Some of the most deeply poetic and profoundly personal texts have been produced by the original explorers during what we today refer to as the “Heroic Age of Antarctic Exploration”. While the old diaries speak of the struggle for survival, this documentary rather resembles a first-hand video journal about the fervour that comes with realising ones aspirations, the hope for making a change, the strains of the sea, and the intensifying pressure of no escape.

More information on our kickstarter project page…

Visiting the end of the world

It is delighted that a team of three, formed by Bruno Danis (ULB), Thomas Saucède (UBFC, France) and Camille Moreau (ULB / UBFC) was invited by Elie Poulin  (U. Chile) to visit Chile as part of the Red de Investigacion de la Biodiversidad Antartica y Subantartica (RIBAS) project. First stop (after a 24-hour delay due to overbooked flight) happened in Punta Arenas, at the extreme South of the South American continent to participate to the IX Congreso Latinoamericano de Ciencia Antartica. We there, discovered (or rediscovered) a peculiar region shaped by thousands of years of extreme climate, a long occupancy by Native peoples and the much more recent settlement of European and Chilean pioneers: Patagonia.

This visit to Punta Arenas also allowed us to carry out some field work in an under-sampled area of the world. Following the road of the end of the world we reached Buque Quemado to sample one of the rare intertidal area we could reach.

It is under very windy conditions that we collected invertebrates in the 7°C waters of the Magellan Straight. There, the macroalgae Macrocystis spp provide habitat for many organisms in their bulk (attaching system) including echinoderms in which we are interested: sea stars and sea urchins, tidal pool were also sampled.

Our second sampling experience took part around 50km away from Punta Arenas and was a diving day from the shore (after our zodiac carrier lost a wheel !). We discovered in Fuerte Bulnes, in and around an underwater forest of algae, an amazing richness and abundance of sea stars, sea urchins and gastropods. Samples were collected for analysis including isotopes, molecular work and morphological characterisations.

 

This week in Punta Arenas provided an amazing experience and incredible opportunities for futher collaboration with a very welcoming community of passionate scientists from all South America. Other activities pursued by our team included enjoying the delicacies of Chili: meat (a lot of it !), seafood, Austral beers, pisco sour and of course the football (which ended up badly for their national team L). #TeTengoFe

Time flies quickly and we have to leave the southernmost city of Chile on the continent to reach the capital Santiago. By luck, and a lot of professionalism, our host Elie booked us window seats in the flight toward Santiago, allowing us to enjoy the amazing scenery of Torre del Paine from the sky.

Work was not over for our team, under a much warmer climate we visited the Museo Nacional de Historia Natural for a visit of the echinoderm collection.

Andrea Martinez, the echinoderm curator and Catalina Merino her assistant gave us a tour of the collection they are getting back on its feet and digitilasing. A huge but essential work for conservation and information about these specimens, which reached 150 year old. This meeting was clearly an open gate for further collaborations and work on this under-valorized collection that needs to be worked out.

 

Last but not least, our team participated in a workshop in Santiago in the presence of the Chilean Minister of Environment to help giving some impulse to the Chilean GBIF node, by meeting and discussing with scientists and policy makers about the need to publish raw biodiversity data in global information networks such as OBIS and GBIF. Many interesting discussions arose, and Chile is at the breach of making major breakthroughs in terms of data publication.

 

These two weeks in Chile unfortunately had to end up at some point. We would like to thank all the people involved in the great time we had there (too many to cite them all!) and look forward for further collaborative work and visits.

 

Special thanks to Andrea, Claudia, Karin, Jo, Christie, Catalina and Javier for featuring or taking the pictures.

 

Camille, Bruno and Thomas

 

New Publication: A Dynamic Energy Budget (DEB) model to describe Laternula elliptica (King, 1832) seasonal feeding and metabolism

A new research work from vERSO and RECTO projects has just been published at PlosOne. This work is part of the effort at BIOMAR (biomar.ulb.ac.be) to gain insight and understanding in the physiological performance of Antarctic invertebrates in a changing environment through the application of Dynamic Energy Budget theory and models (BIOMAR-DEB). This publication results from a collaboration with the Korean Polar Research Institute (KOPRI). Published in Open access, the full article can be read and downloaded from here.

Specimen of Laternula elliptica, research object of the published article © oikonos.org

 

A Dynamic Energy Budget (DEB) model to describe Laternula elliptica (King, 1832) seasonal feeding and metabolism

by Antonio Agüera, In-Young Ahn, Charlène Guillaumot & Bruno Danis

Abstract

Antarctic marine organisms are adapted to an extreme environment, characterized by a very low but stable temperature and a strong seasonality in food availability arousing from variations in day length. Ocean organisms are particularly vulnerable to global climate change with some regions being impacted by temperature increase and changes in primary production. Climate change also affects the biotic components of marine ecosystems and has an impact on the distribution and seasonal physiology of Antarctic marine organisms. Knowledge on the impact of climate change in key species is highly important because their performance affects ecosystem functioning. To predict the effects of climate change on marine ecosystems, a holistic understanding of the life history and physiology of Antarctic key species is urgently needed. DEB (Dynamic Energy Budget) theory captures the metabolic processes of an organism through its entire life cycle as a function of temperature and food availability. The DEB model is a tool that can be used to model lifetime feeding, growth, reproduction, and their responses to changes in biotic and abiotic conditions. In this study, we estimate the DEB model parameters for the bivalve Laternula elliptica using literature-extracted and field data. The DEB model we present here aims at better understanding the biology of L. elliptica and its levels of adaptation to its habitat with a special focus on food seasonality. The model parameters describe a metabolism specifically adapted to low temperatures, with a low maintenance cost and a high capacity to uptake and mobilise energy, providing this organism with a level of energetic performance matching that of related species from temperate regions. It was also found that L. elliptica has a large energy reserve that allows enduring long periods of starvation. Additionally, we applied DEB parameters to time-series data on biological traits (organism condition, gonad growth) to describe the effect of a varying environment in food and temperature on the organism condition and energy use. The DEB model developed here for L. elliptica allowed us to improve benchmark knowledge on the ecophysiology of this key species, providing new insights in the role of food availability and temperature on its life cycle and reproduction strategy.

 

Find us at the #SCARbio17 symposium

The Marine Biology Lab is making a significant contribution to the SCAR biology symposium, which is taking place in Leuven, Belgium between 10-14th of July 2017.
Bruno Danis is co-chairing the Local Organising Committee (LOC) with Anton Van de Putte (Royal Belgian Institute of Natural Sciences) and participates in the SCAR Expert Groups on Antarctic Biodiversity Informatics and Antarctic Birds and Marine Mammals, respectively as Chief Officer and member. Bruno is also organising a side event on the Belgica120 expedition.

Philippe Dubois and Chantal De Ridder are also members of the LOC.

In terms of scientific contributions, our team will present the following papers:

  • Antonio Agüera: Understanding the role of environmental conditions on the performance of Laternula elliptica (King & Broderip) in King George Island
  • Sarah Di Giglio: Acid-base physiology of the Antarctic sea urchin Sterechinus neumayeri: differences according to environmental conditions?
  • Philippe Dubois: Is the Sub-antarctic sea urchin Abatus cordatus threatened by ocean acidification?  AND Acid-base physiology of Antarctic and Sub-antarctic sea urchins and their resilience to ocean acidification
  • Salomé Fabri-Ruiz: Improving the quality of species distribution models at large spatial scale to better future predictions
  • Charlène Guillaumot: Modelling species distribution: influences of temporal, spatial, and sampling heterogeneities in data-poor areas. An example from the Kerguelen Plateau.

You can find the details about the programme on this eDoc.

See you at the symposium!

Hot off the press: biogeography of Southern Ocean sea stars

Our paper on the biogeography of Southern Ocean sea stars is out in Journal of Biogeography:

Reproductive strategy as a piece of the biogeographic puzzle: a case study using Antarctic sea stars (Echinodermata, Asteroidea), by Camille Moreau et al.

Aim: To describe and analyse asteroid biogeographic patterns in the Southern Ocean (SO) and test whether reproductive strategy (brooder versus broad- caster) can explain distribution patterns at the scale of the entire class. We hypothesize that brooding and broadcasting species display different biogeo- graphic patterns.

Location: Southern Ocean, south of 45 °S.

Methods: Over 14,000 asteroid occurrences are analysed using bootstrapped spanning network (BSN), non-metrical multidimensional scaling (nMDS) and clustering to uncover the spatial structure of faunal similarities among 25 bioregions.

Results: Main biogeographic patterns are congruent with previous works based on other taxa and highlight the isolation of New Zealand, the high richness in the Scotia Arc area particularly of brooding species, an East/West Antarctic dif- ferentiation, and the faunal affinities between South America and sub-Antarctic Islands. Asteroids show lower endemism levels than previously reported with 29% of species occurring in Antarctica only. In particular, asteroids from Tierra del Fuego showed affinities with those of West Antarctica at the species level, suggesting a recent mixing of assemblages. Biogeographic patterns are highly linked to reproductive strategy. Patterns also differ according to the tax- onomic level, revealing the underlying role of historical factors.

Main conclusions: Patterns of sea star biogeography are consistent with results obtained for other marine groups and are strongly linked to reproductive strategy.