Probing diversity in the plankton: using patterns in Tintinnids (planktonic marine ciliates) to identify mechanisms

Abstract

In diversity research, the use of survey data appears to have declined in favour of experimental or modeling approaches because direct relationships are difficult to demonstrate. Here we show that use of field data can yield information concerning the mechanisms governing diversity. First, we establish that tintinnids display a global latitudinal pattern of diversity similar to other pelagic organisms; species numbers appear to peak between 20°and 30°north or south. This common large scale spatial trend has been attributed to the gradient in water column structure across the global ocean. We then examine the generality of a relationship between planktonic diversity and water column structure by considering data from the Mediterranean Sea, in which water column structure changes seasonally. Among populations of foraminifera, tintinnids, and the dinoflagellates of the genus Ceratium, we compare data from trans-Mediterranean sampling conducted at different times and monthly changes in species richness at single sites. We find that water column structure alone appears to be a poor predictor of temporal changes in diversity. Lastly, we present an example of temporal changes in tintinnid diversity based on data from an oceanographic sampling station in the N. W. Mediterranean where resources, as chlorophyll, appear distinctly unrelated to changes in water column structure. We show that short-tem temporal changes in diversity (week to week shifts) can be related to changes in chlorophyll concentration. We conclude that in tintinnids diversity can be directly linked to characteristics of food resources.

Scaling patterns of plankton diversity: a study of ciliates in a tropical coastal lagoon

“…4A, D). Such temporal variability of ciliate diversity is a phenomenon noted by others (e.g., Widdicombe et al, 2002;Barría de Cao et al, 2005;Dolan et al, 2006b;Sitran et al, 2007). However, our analysis extended the recognition that immigration alters diversity (Fig.…”

“…In a recent study of planktonic ciliate diversity, Dolan et al (2006b) suggested, for diversity research, that the use of survey data seems to be declining in favour of experimental and modelling approaches. Possibly this is because there remains a dichotomy between the more mundane but concrete and essential collection of field data and the more provocative theoretical approaches taken by experimental and modelling studies.…”

“…For instance, Hutchinson (1961) considered that plankton diversity could be explained by fluctuating environmental factors, and more recently Loreau & Mouquet (1999) elaborate on this by suggesting species diversity, in general, is altered by two fundamental processes: ''local' ' (e.g., competition, predation, variations in abiotic factors) and ''largerscale or regional'' (e.g., colonisation, immigration, extinction) processes. Surprisingly, although spatial and temporal variation in plankton diversity is regularly investigated in surveys, experiments, and models (Dolan et al, 2006b), there remains an inadequate provision of methods for predicting spatial patchiness of plankton diversity, although inroads are being made to this end (see Beaugrand & Ibañez, 2002;Kienel & Kumke, 2002). Here we, therefore, develop and apply a suite of complementary geostatistical and multiple-regression analysis tools, previously used to approach the study of patchiness of plankton abundance (Bulit et al, 2003(Bulit et al, , 2004Díaz-Á valos et al, 2006), to assess diversity.…”

Global Diversity of Aloricate Oligotrichea (Protista, Ciliophora, Spirotricha) in Marine and Brackish Sea Water

“…In planktonic foraminifera and tintinnids, however, the number of taxa increases from high to low latitudes with two peaks near the Tropics of Cancer and Capricorn (20–30°N and S, respectively; [165]–[167]). …”

Planktonic equatorial diversity troughs: fact or artifact? Latitudinal diversity gradients in Radiolaria

“…Early assessments of biological diversity across the globe showed that marine and terrestrial low latitude areas host higher numbers of species than the poles (Thorson 1957, Stehli et al 1969. On the other hand, in contrast to many reports based on terrestrial and freshwater organisms, most of the recent surveys on marine plankton concluded that species numbers peak in the subtropics or in the transition zones, whereas the equator is associated with a plateau or a drop in their numbers (Boltovskoy 1987, McGowan and Walker 1993, Rutherford et al 1999, Macpherson 2002, Worm et al 2005, Dolan et al 2006, Rombouts et al 2009, Barton et al 2010, Tittensor et al 2010, Powell et al 2012, Yasuhara et al 2012. On the other hand, in contrast to many reports based on terrestrial and freshwater organisms, most of the recent surveys on marine plankton concluded that species numbers peak in the subtropics or in the transition zones, whereas the equator is associated with a plateau or a drop in their numbers (Boltovskoy 1987, McGowan and Walker 1993, Rutherford et al 1999, Macpherson 2002, Worm et al 2005, Dolan et al 2006, Rombouts et al 2009, Barton et al 2010, Tittensor et al 2010, Powell et al 2012, Yasuhara et al 2012.…”