Pau Balaguer

Spatial and seasonal variability of the macro-invertebrate community of a rocky coast in Mallorca (Balearic Islands): implications for bioerosion

The number of the main macro-invertebrate species grazing on the microalgal film on rocky coasts was evaluated at six closely located stations on Mallorca (Balearic Islands). The main bioerosive species at the sites studied were Melaraphe neritoides (L., 1758), Patella rustica (L., 1758), Monodonta turbinata (Born, 1780) and Lepidochitona corrugata (Reeve, 1848). The transects considered shared the same general environmental conditions and species pool. The aim of this study was to compare the effects exerted by the vertical gradient with those exerted by other sets of environmental variables. These sets were, namely, (1) inter-seasonal differences, (2) inter-transect differences (comprising degree of wave-exposure and lithological differences) and (3) effects of the micro-morphology (i.e., crevices, basin pools and other small-scale structures). The main null hypothesis verified was that species composition remains constant after assessing the effect of the vertical gradient. This hypothesis is largely rejected here. The main factor modelling the species composition was the vertical gradient (accounting for 31.6% of variability) whereas the percentages of variability yielded by the other sets individually were smaller but significant (P<0.001). Inter-transect differences (including degree of wave exposure and lithology) accounted for 24.9% of the variability. Seasonal differences accounted for 6.3%, small-scale morphology for 4.5%, and wave-height for 1.6%. The main conclusions obtained from these results are that the most basal strip of the coastline undergoes the largest bioerosive rates. Similarly, the sites exposed to wave action will undergo a larger bioerosive impact than the sheltered sites (possibly because they are more damp). These biotic and abiotic effects taken together would result in a maximisation of erosion rates in areas that are porous, exposed and located near the sea.

Exploring rock coast bioerosion: rock fragment intestine transit time and erosion rates computation of the gastropod Monodonta articulata (Lamarck, 1822)

ABSTRACT Vidal, M., Fornós, J.J., Gómez-Pujol, L., Palmer, M., Pons, G.X., Balaguer, P., 2013. Exploring rock coast bioerosion: rock fragment intestine transit time and erosion rates computation of the gastropod Monodonta articulata (Lamarck, 1822) Coastal rock bioerosion research is well established. Otherwise there is the need to improve the way in which bioerosion rates are calculated. Since the findings of McLean (1967), it has been assumed that the dry weight of pellets collected after 24 hours provides an estimate of the amount of organism daily erosion. This is an assumption that relies largely on initial experimental procedures lacking any empirical ascertainment. This paper assess what is the transit time of the rock fragments through the intestine of the gastropod Monodonta articulata, and the implications of applicability of this temporal framework to the computation of a more precise estimation of the bioerosion throughout laboratory experiments. Our results suggest that for the gastropod Monodonta articulata, the major part of the eroded and ingested rock is defecated during feeding time. According to this, the confidence of bioerosion rates values calculated by means of faecal pellet collection based on 24-hour time frame can be concluded. Erosion rates for M. articulata activity in limestone rock samples have been estimated to range between 8.00 mg·ind−1·day−1 to 10.10 mg·ind−1·day−1.

The Impact of New Multi-platform Observing Systems in Science, Technology Development and Response to Society Needs; from Small to Large Scales…

New monitoring technologies are key components of ocean observatories, also called marine research infrastructures being implemented in the worlds oceans. As a result, new capabilities to characterise, in quasi-real time, the ocean state and its variability at small scales exist today. The challenge is the integration of theses multiplatform observing and forecasting systems to (a) monitor the variability at small scales (e.g. mesoscale/weeks) in order to (b) resolve the sub-basin/seasonal and inter-annual variability and by this (c) establish the decadal variability, understand the associated biases and correct them. The challenge is also to change focus and now monitor from small to large scales. SOCIB is leading this new small to large-scale multi-platform approach in ocean observation. Some examples are presented and discussed together with initial ideas on the optimal design of an observational network in the world oceans, responding to science priorities, technology development and response to strategic society needs.