Abstract:Within the COST action EMBOS (European Marine Biodiversity Observatory System) the degree and variation of the diversity and densities of soft-bottom communities from the lower intertidal or the shallow subtidal was measured at twenty-eight marine sites along the European coastline (Baltic, Atlantic, Mediterranean) using jointly-agreed and harmonised protocols, tools and indicators. The hypothesis tested was that the diversity for all taxonomic groups would decrease with increasing latitude. The EMBOS system d… Show more
“…an increase of species richness with higher latitude (e.g. in the North Sea, Heip et al, 1992;Rees et al, 1999; along the Argentina coasts, Doti et al, 2014) or a bell-shaped trend (Gray, 2000;Hummel et al, 2016). Our study revealed a more complex pattern: a bell-shaped curve peaking in Brittany between 47°N to 49°N latitude (Figure 4).…”
Section: Accepted Manuscriptsupporting
confidence: 44%
“…However, because it includes the transition between the Northern European seas and the Lusitanian province, we also expect the latitudinal pattern along French Atlantic coasts to be more complex than a simple linear model (e.g. Roy et al, 1998;Hummel et al, 2016). Indeed, biogeographic boundaries potentially host high species richness by combining the diversity of the adjoining biogeographic areas and sustaining species not found elsewhere (Kark and van Rensburg, 2006).…”
International audienceThis study aims to describe the patterns of soft bottom macrozoobenthic richness along French coasts. It is based on a collaborative database developed by the “Réseau des Stations et Observatoires Marins” (RESOMAR). We investigated patterns of species richness in sublittoral soft bottom habitats (EUNIS level 3) at two different spatial scales: 1) seaboards: English Channel, Bay of Biscay and Mediterranean Sea and 2) 0.5° latitudinal and longitudinal grid. Total observed richness, rarefaction curves and three incidence-based richness estimators (Chao2, ICE and Jacknife1) were used to compare soft bottom habitats species richness in each seaboard. Overall, the Mediterranean Sea has the highest richness and despite higher sampling effort, the English Channel hosts the lowest number of species. The distribution of species occurrence within and between seaboards was assessed for each major phylum using constrained rarefaction curves. The Mediterranean Sea hosts the highest number of exclusive species. In pairwise comparisons, it also shares a lower proportion of taxa with the Bay of Biscay (34.1%) or the English Channel (27.6%) than that shared between these two seaboards (49.7%). Latitudinal species richness patterns along the Atlantic and English Channel coasts were investigated for each major phylum using partial LOESS regression controlling for sampling effort. This showed the existence of a bell-shaped latitudinal pattern, highlighting Brittany as a hotspot for macrobenthic richness at the confluence of two biogeographic provinces
“…an increase of species richness with higher latitude (e.g. in the North Sea, Heip et al, 1992;Rees et al, 1999; along the Argentina coasts, Doti et al, 2014) or a bell-shaped trend (Gray, 2000;Hummel et al, 2016). Our study revealed a more complex pattern: a bell-shaped curve peaking in Brittany between 47°N to 49°N latitude (Figure 4).…”
Section: Accepted Manuscriptsupporting
confidence: 44%
“…However, because it includes the transition between the Northern European seas and the Lusitanian province, we also expect the latitudinal pattern along French Atlantic coasts to be more complex than a simple linear model (e.g. Roy et al, 1998;Hummel et al, 2016). Indeed, biogeographic boundaries potentially host high species richness by combining the diversity of the adjoining biogeographic areas and sustaining species not found elsewhere (Kark and van Rensburg, 2006).…”
International audienceThis study aims to describe the patterns of soft bottom macrozoobenthic richness along French coasts. It is based on a collaborative database developed by the “Réseau des Stations et Observatoires Marins” (RESOMAR). We investigated patterns of species richness in sublittoral soft bottom habitats (EUNIS level 3) at two different spatial scales: 1) seaboards: English Channel, Bay of Biscay and Mediterranean Sea and 2) 0.5° latitudinal and longitudinal grid. Total observed richness, rarefaction curves and three incidence-based richness estimators (Chao2, ICE and Jacknife1) were used to compare soft bottom habitats species richness in each seaboard. Overall, the Mediterranean Sea has the highest richness and despite higher sampling effort, the English Channel hosts the lowest number of species. The distribution of species occurrence within and between seaboards was assessed for each major phylum using constrained rarefaction curves. The Mediterranean Sea hosts the highest number of exclusive species. In pairwise comparisons, it also shares a lower proportion of taxa with the Bay of Biscay (34.1%) or the English Channel (27.6%) than that shared between these two seaboards (49.7%). Latitudinal species richness patterns along the Atlantic and English Channel coasts were investigated for each major phylum using partial LOESS regression controlling for sampling effort. This showed the existence of a bell-shaped latitudinal pattern, highlighting Brittany as a hotspot for macrobenthic richness at the confluence of two biogeographic provinces
“…The EMBOS network of marine observatories covers a great part of European coasts, including sites in both the NE Atlantic and the Mediterranean (Figure 1A, Supplementary Materials, Appendix A). This offers the opportunity to investigate patterns and processes at the pan-European scale (see also Hummel et al, 2016; Kotta et al , 2016; Puente et al, in press). Fig.…”
Examining how variability in population abundance and distribution is allotted among different spatial scales can inform of\ud
processes that are likely to generate that variability. Results of studies dealing with scale issues in marine benthic communities suggest that variability is concentrated at small spatial scales (from tens of centimetres to few metres) and that spatial patterns of variation are consistent across ecosystems characterized by contrasting physical and biotic conditions, but this has not been formally tested. Here we quantified the variability in the distribution of intertidal rocky shore communities at a range of spatial scales, from tens of centimetres to thousands of kilometres, both in the NE Atlantic and the Mediterranean, and tested whether the observed patterns differed between the two basins. We focused on canopy-forming macroalgae and associated understorey assemblages in the low intertidal, and on the distribution of Patella limpets at mid intertidal levels. Our results highlight that patterns of spatial variation, at each scale investigated, were consistent between the Atlantic and the Mediterranean, suggesting that similar ecological processes operate in these regions. In contrast with former studies, variability in canopy cover, species richness and limpet abundance was equally distributed among spatial scales, possibly reflecting the fingerprint of multiple processes. Variability in community structure of low intertidal assemblages, instead, peaked at the largest scale, suggesting that oceanographic processes and climatic gradients may be important. We conclude that formal comparisons of variability across scales nested in contrasting systems are needed, before any generalization on patterns and processes can be made
“…However, there are multiple examples where LDGs have not been found in marine systems (Rivadeneira, Thiel, González, & Haye, 2011;Valdovinos, Navarrete, & Marquet, 2003), or the relationship is far weaker than in terrestrial systems or inverse (Liuzzi, López Gappa, & Piriz, 2011;Saeedi, Dennis, & Costello, 2017;Santelices & Marquet, 1998), or the peak of species richness is not centred around the equator (Chaudhary, Saeedi, & Costello, 2016;Levinton & Mackie, 2013;Roy, Jablonski, Valentine, & Rosenberg, 1998). Furthermore, the shape and strength of the relationship often varies among basins or taxa (Astorga, Fernández, Boschi, & Lagos, 2003;Hummel et al, 2017;Macpherson, 2002) and can depend on the spatial scales examined (Willis & Whittaker, 2002). For instance, a large proportion of our knowledge on marine LDGs patterns comes from (1) studies based on meta-analyses of existing information rather than surveys using standardized methods (but see Navarrete, Lagos, & Ojeda, 2014;Rivadeneira, Navarrete, & Fernandez, 2002), (2) studies that focused solely on α-diversity and did not consider other components of diversity (but see Anderson, Tolimieri, & Millar, 2013;Navarrete et al, 2014) or (3) studies that focused on a specific taxonomic group (but see Bulleri et al, 2012).…”
Aim
We evaluated whether patterns of species diversity (α, β and γ) of rocky shore assemblages followed latitudinal gradients (i.e. LDGs) along the South American coasts, and tested hypotheses related to potential processes sustaining or disrupting the expected LDG pattern at various spatial scales.
Location
Coasts of South America.
Taxon
Macroalgae and sessile/slow‐moving macrofauna on intertidal rocky shores.
Methods
We evaluated changes in species composition across 143 sites. The degree of replacement and loss of species at different spatial scales (i.e. coasts, regions and sites) were estimated to help distinguish among ecological, historical and evolutionary hypotheses for explaining LDGs. Furthermore, components of diversity and taxonomic distinctness were measured, and variability in these measures was decomposed using analysis of covariance. Finally, we examined relationships between diversity and a suite of environmental and anthropogenic variables to identify potential mechanisms that may be responsible for the reported spatial relationships.
Results
Species composition varied with latitude, and this variability was relatively consistent on both coasts. At all spatial scales, replacement of species was the dominant phenomenon (>95%), rather than loss in the total number of species (<5%). LDGs were strongly dependent on the diversity component and the spatial scale: generally, positive for regional β‐diversity, negative for α‐diversity and site β‐diversity. Sea surface temperature (SST) was the variable that best explained patterns of diversity along both coasts (14%–22%), but other regional and local environmental variables associated with river discharges, upwelling, confluence of currents, tides and anthropogenic pressures also accounted for an important portion of variation (5%–14% each).
Main conclusions
Species diversity of South American rocky shores followed, with interruptions, LDGs. The trend of those LDGs, however, depended on the scale and metric used to describe diversity. It is proposed that patterns of LDGs at various scales are not the result of a single overarching process but are strongly influenced by local and regional processes. Although the most evident environmental gradient was the decrease in SST towards the south, it was demonstrated that regional and local environmental variables were also important for understanding the increase in regional β‐diversity towards the tropics.
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