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…

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!

The RAATD workshop

This week, Bruno Danis is attending the fourth RAATD workshop, hosted at the CESAB (Center for Synthesis and Analysis of Biodiversity), in Aix-en-Provence. 10 participants from 7 countries are attending the meeting.

The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a multispecies assessment of habitat use of Antarctic meso- and top predators in the Southern Ocean based on existing animal tracking data to identify Areas of Ecological Significance, i.e. regions that are important for foraging to a range of predators and which, consequently, present an important biodiversity. RAATD was initiated by the SCAR Expert Group on Birds and Marine Mammals (EG-BAMM), and provides (i) a greater understanding of fundamental ecosystem processes in the Southern Ocean, (ii) facilitate future projections of predator distributions under varying climate regimes, and (iii) provide input into spatial management planning decisions for management authorities such as the Convention on the Conservation of Antarctic Marine Living Resources. The synopsis of multi-predator tracking data will also expose potential gaps of data coverage in regions or seasons that are important but underrepresented, possibly due to biases in the spatial, temporal, or taxonomic distribution of research effort. We have collated all available tracking data by research groups that worked in the Antarctic since the 1990s. We have then establish a preliminary publicly accessible repository of these data. The final publicly available repository will only have the raw data that data holders have agreed to share and will contain data from almost 40 contributors from 12 national Antarctic programs. The dataset contains data on 17 predator species, with more than 3400 individual animals, and more than 2.5 million data points. We will also share the outputs of the project, including filtered and processed versions of these data, and habitat model outputs.

 

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.

Camille is off to the ACE Expedition

This season 2017, Camille Moreau, PhD student at the Universities of Brussels (ULB) and Dijon, is joining a major Swiss-led research expedition circum-navigating the Antarctic: the ACE (Antarctic Circumnavigation Expedition).

In the framework of his PhD project, Camille will take part as a member of the ASCCC (Antarctic Seabed Carbon Capture Change) team gathering scientists from master students to senior scientists. Their research will investigate the importance of sea bed animals in carbon cycling and how climate change will impact these processes in the Southern Ocean.

The project is led by David Barnes, a marine biologist at the British Antarctic Survey and zoology/ecology professor at the University of Cambridge. He took part in the first leg of the expedition, from Cape Town to Hobart. Camille will join the team in Hobart, Tasmania for the second leg of the expedition, a which will take the ship to Punta Arenas, Chile. The team will have the opportunity to visit rarely studied sub-Antarctic islands (Macquarie, Balleny, Scott, Peter the 1st and Diego Ramirez). They will also carry on researches around the Mertz Glacier in Antarctica.

Collection of benthic organisms using a trawl, investigation of marine debris ashore and use of a remotely operated vehicle (ROV) will organise their daily life for the next few weeks.

For more information regarding the expedition and the ASCCC project follow this link or follow their progress on twitter @ACE_Expedition and @asccc_news.

Carnet de Mission Rencontres : Philippe Dubois

Carnet de Mission Rencontres est un format complémentaire à Carnet de Mission qui vous présente plus en détails les protagonistes de l’aventure Kerguelens. Une ouverture sur les différentes vocations que l’on croise sur la route des Terres Australes Françaises !

Interview de Philippe Dubois.