Daphnia species diversity in Kenya, and a key to the identification of their ephippia

Mergeay, Joachim; Verschuren, Dirk; Meester, Luc De

doi:10.1007/1-4020-4111-x_25

Cited by 22 publications

(37 citation statements)

References 38 publications

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“…2a-g), among which six were frequently present (.10% of the 383 observations) and abundant (at least 1% of the overall fossil inventory). This species diversity amounts to all Daphnia taxa known from East Africa, apart from the Daphnia obtusa complex, which is restricted to high-mountain environments (Mergeay et al 2005).…”

Section: Resultsmentioning

confidence: 99%

“…Abundances of Daphnia and fish fossils were expressed as the number of remains per gram of dry sediment per year (i.e., their production flux) to correct for both changes in sedimentation rate and sediment compaction with depth. The Daphnia were identified to species morphologically and/or genetically (Mergeay et al 2005(Mergeay et al , 2006b). Variation in temporal resolution between sampled intervals was not correlated ) Abundance changes over time in the Daphnia species inhabiting Lake Naivasha over the past 1800 years (DM represents dry mass) in relation to (h) reconstructed changes in fish abundance, (i) lake water salinity (represented by the conductivity of dissolved salts), and ( j) lake depth, as well as (k) the stratigraphic variation in sediment composition that allowed with Daphnia species richness (Pearson product-moment correlation, r ¼ 0.053, P ¼ 0.296) or Shannon diversity (r ¼ 0.071, P ¼ 0.163).…”

Section: Reconstruction Of Daphnia Community Change Through Timementioning

confidence: 99%

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Priority effects and species sorting in a long paleoecological record of repeated community assembly through time

Mergeay

Meester

Eggermont

et al. 2011

Ecology

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Abstract. We studied the relative roles of environmental species sorting and priority effects in the assembly of ecological communities on long time scales, by analyzing community turnover of water fleas (Daphnia) in response to strong and recurrent environmental change in a fluctuating tropical lake. During the past 1800 years, Lake Naivasha (Kenya) repeatedly fluctuated between a small saline pond habitat during lowstands and a large freshwater lake habitat during highstands. Starting from a paleoecological reconstruction, we estimated the role of priority effects in Daphnia community assembly across 16 of these habitat turnovers and compared this with the response of the community to reconstructed changes in three environmental variables important for species sorting.Our results indicate that the best predictor of Daphnia community composition during highstands was the community composition just prior to the transition from lowstands to highstands. This reflects a long-lasting priority effect of late lowstand communities on highstand communities, arising when remnant lowstand populations fill newly available ecological space in the rapidly expanding lake habitat. Species sorting and priority effects had a comparable but relatively small influence on community composition during the lowstands. Moreover, these priority effects decayed rapidly with time as Daphnia communities responded to environmental change, in contrast with the highstand communities where priority effects lasted for several decades.

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Section: Resultsmentioning

confidence: 99%

Section: Reconstruction Of Daphnia Community Change Through Timementioning

confidence: 99%

Priority effects and species sorting in a long paleoecological record of repeated community assembly through time

Mergeay

Meester

Eggermont

et al. 2011

Ecology

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“…Ephippium morphotype M1 was identified as belonging to species of the Daphnia pulex Leydig, 1860 group, based on two morphological identification keys created by Vandekerkhove (2004) and Mergeay et al (2005). Vandekerkhove's key also permitted us to presume that the M3 morphotype is related to Daphnia ambigua Scoufield, 1946 species.…”

Section: Resultsmentioning

confidence: 99%

Brook trout (Salvelinus fontinalis) extinction in small boreal lakes revealed by ephippia pigmentation: a preliminary analysis

2016

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Ephippium pigmentation is a plastic trait which can be related to a trade-off between visual predation pressure and better protection of cladoceran eggs against different types of stress. Experimental studies showed that planktivorous fish exert a greater predation pressure on individuals carrying darker ephippia, but little is known about the variation of ephippium pigmentation along gradients of fish predation pressure in natural conditions. For this study, our sampling design included four small boreal lakes with known fish assemblages. Two of the lakes have viable brook trout (Salvelinus fontinalis) populations, whereas the other two lakes experienced brook trout extinctions during the 20 th century. Cladoceran ephippia were extracted from sediment cores at layers corresponding to the documented post-extinction phase (1990's) and from an older layer (1950's) for which the brook trout population status is not known precisely. Our first objective was to determine whether brook trout extinction has a direct effect on both ephippium pigmentation and size. Our second objective was to give a preliminary assessment of the status of brook trout populations in the 1950's by comparing the variation in ephippia traits measured from this layer to those measured in the 1990's, for which the extinction patterns are well known. Cost-effective image analysis was used to assess variation in pigmentation levels in ephippia. This approach provided a proxy for the amount of melanin invested in each ephippium analysed. Our study clearly shows that ephippium pigmentation may represent a better indicator of the presence of fish predators than ephippium size, a trait that showed a less clear pattern of variation between lakes with and without fish. For the 1990's period, ephippia from fishless lakes were darker and showed a slight tendency to be larger than ephippia from lakes with brook trout. However, no clear differences in either ephippium size or pigmentation were observed between the 1990's and 1950's layers within each lake. This suggests that brook trout extinction already occurred before the 1950's, or that brook trout population abundance was already extremely low before the 1990's. Our preliminary study shows that ephippium pigmentation can be used as a tool to quickly assess present and past predation levels on zooplankton when only sediment samples are available.

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“…Hence, the current South African D. pulex is most likely an exotic hybrid that has replaced a native D. pulex, which was closer to the European populations (Mergeay et al, 2006 (Sars, 1916;Fig. 10), which is found also in East Africa (Löffler, 1968, Mergeay et al, 2005, wide molecular surveys (De Gelas and De Meester, 2005) have not taken the South African populations into account, therefore we cannot speculate on their origin. Adamowicz et al (2009) (Fig.…”

Section: Neglected South African Taxa: the Example Of Daphniamentioning

confidence: 91%

“…D. dolichocephala and D. cf. gibba are not restricted to South Africa, but extend up to Kenya (Mergeay et al, 2005), whereas D. propinqua, D. coronata and D. tenuispina have not been reported more north. Our knowledge about the exact distribution and even our definition of the latter taxa is limited, yet these forgotten names could well shelter true endemics of Southern Africa.…”

Section: Neglected South African Taxa: the Example Of Daphniamentioning

confidence: 92%

Endemism in the Cladocera (Crustacea: Branchiopoda) of Southern Africa

2013

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Daphnia species diversity in Kenya, and a key to the identification of their ephippia

Cited by 22 publications

References 38 publications

Priority effects and species sorting in a long paleoecological record of repeated community assembly through time

Priority effects and species sorting in a long paleoecological record of repeated community assembly through time

Brook trout (Salvelinus fontinalis) extinction in small boreal lakes revealed by ephippia pigmentation: a preliminary analysis

Endemism in the Cladocera (Crustacea: Branchiopoda) of Southern Africa

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