Measuring settlement rates of sea urchins. New paper out!

by Owen Wangensteen

Team members of the ChallenGen Project at the University of Barcelona, in collaboration with scientists from the University of La Laguna (Canary Islands) have just published a new paper on Scientia Marina journal, describing and testing new designs of artificial collectors for quantitative assessment of settlement rates in sea urchins.

The study of population dynamics of sea urchins is crucial for understanding the ecology of Mediterranean and temperate Atlantic rocky shores, since these echinoderms are often the main herbivore species in shallow benthic ecosystems and they are responsible of linking the primary production from seaweeds to other higher levels of the trophic chains. Many sea urchin populations may be limited by the settlement rates (the process by which the planktonic sea urchin larvae settle and become juvenile sea urchins). Methods for measuring these settlement rates were not standardized and yielded non-comparable results. The work presented in this paper, carried out in parallel at Canary Islands and Costa Brava (Spain) shows that three-dimensional collectors made from “bioballs” (a biofilm-friendly, high surface material often used as filters in aquaria) are the most suitable device for this assessment, allowing for an accurate and repeatable measurement of this elusive, yet important, ecological process.

The best part is that these bioballs collectors are useful not only for sea urchins settlers. They could be suitable for assessing settlement and colonization rates for a wide-range of marine invertebrates and can help marine biologists to get a more accurate view of the population dynamics of many species present in benthic ecosystems.

The three types of collector tested in this work: plastic biofilter ball (A, C), vertical brush (B, D) and horizontal triangular mat of coconut fibre (B, E).

Monitoring ascidians in the Venetian Lagoon

by Maria Casso

A wood pile dolphin, full of benthic organisms, and half eaten by wood-boring species.

Marco and the fog during the sampling.

The Benthic Ecology research group from the Istituto di Scienze Marina, ISMAR (Consiglio Nazionale delle Ricerche, CNR), placed in the Venetian Lagoon, is hosting me for a 3 months research stay. They focuses on ecology of coastal transitional ecosystems, specially benthic communities. More recently, they are interested on wood-boring marine organisms (shipworms and gribbles). This is very important in a place like the Venetian Lagoon as it has a large wooden maritime cultural heritage.

The aim of my stay in Venice is to study the invasive ascidians, which grow on top of those wooden marine structures. To do this, yesterday we went to a field trip around the Venetian Lagoon with Davide Tagliapietra, Marco Sigovini and Irene Guarneri. It was foggy in the beginning but more sunny at the end of the sampling. The objective of the field trip was to determine the distribution of some invasive ascidians and to collect samples for aquaria experiments.

ChallenGen at the workshop “Application of genomic tools for benthic monitoring”

by Xavier Turon

The 4-5 April 2016, the Natural History Museum of Geneva (Switzerland) hosted the workshop “Application of genomic tools for benthic monitoring of marine environment: from technology to legal and socio-economic aspects”, organised by Prof. Jan Pawlowski of the University of Geneva.

The workshop was intended as a forum for the exchange of ideas about the potential of eDNA- related techniques for assessing biodiversity and the impact of human activities on it. It was attended by environmental professionals, members of regulating bodies, and scientists. The presentations and discussion were very lively, and the overarching idea is that DNA-derived indicators may be effectively used in the field of environmental monitoring (as they are in other applied sciences). However, more development and standardization is necessary before they can be integrated with- or substitute altogether- current techniques using morphology-based indicators, which are slow, time-consuming, and reliant on a worlwide dwindling taxonomic expertise.

Xavier Turon and Owen Wangensteen contributed to the workshop with the talk “Issues in metabarcoding of marine benthos”, where they pinpointed some conflicting issues, such as the use of DNA vs RNA, the choice between 18S rDNA or COI markers, or the use of a fixed vs a variable threshold for clustering sequences into MOTUs. The talk was illustrated with results obtained in the projects CHALLENGEN and METABARPARK.

Xavier Turon and Tom Wilding, of the Scottish Association for Marine Science, at the entrance of the Natural History Museum, with a lovely pet!