Francesc Mesquita-Joanes

The Ecology of Ostracoda Across Levels of Biological Organisation from Individual to Ecosystem: A Review of Recent Developments and Future Potential

Abstract Palaeoenvironmental and palaeoclimatic applications of fossil ostracods rely on a uniformitarian approach underpinned by knowledge of the biology and ecology of living species. This review reveals that in recent decades, major advances have been made in the understanding of species’ abiotic niches in relation to their preferences for different water chemistries and temperatures. However, the underlying ecophysiological mechanisms for such preferences are still largely unknown. Only a few works analyse in detail aspects of population growth or species interactions (competition, predation) in the framework of classical ecological theories. Similarly, the role of Ostracoda in the assembly and functioning of aquatic biological communities is just starting to be recognised. We finally stress the relevance of Quaternary research on ostracod palaeoecology for testing ecological theories of community succession and dynamics in the long term, which may provide answers that standard ecological studies on living communities cannot, due to an inappropriate timescale.

An invaded invader: high prevalence of entocytherid ostracods on the red swamp crayfish Procambarus clarkii (Girard, 1852) in the Eastern Iberian Peninsula

The American red swamp crayfish Procambarus clarkii (Girard, 1852) was introduced in 1973 into the Iberian Peninsula for commercial purposes. As a result of both the expansion from the Iberian Peninsula and, probably, further introductions in other European countries, now it is widely distributed throughout much of Europe. The ecological impacts of this invading crayfish have received increasing attention, but nothing is known about its symbiotic entocytherid ostracods outside the American continent. The present survey has examined more than 200 crayfishes from 12 localities distributed over a wide area of Eastern Spain. Entocytherid ostracods were extracted from individual crayfishes and they were identified, counted, assigned to developmental instars and sexed. In all the study locations but one, we found at least one crayfish individual infected by entocytherid ostracods and the species determined was the same in all cases: Ankylocythere sinuosa (Rioja, 1942). The number of ostracods on individual P. clarkii varied notably in relation to crayfish size and also differed significantly among sampling sites. The crayfish size effects on ostracod densities might be related to the amount of resources and to the crayfish age and moulting frequency affecting ostracod distribution and population structure. In addition, the spatial variation in ostracod densities could also be related to site-specific habitat traits and the variability of crayfish population dynamics. Our study represents the first citation of an alien entocytherid species in Europe and demonstrates its wide distribution in the Iberian Peninsula. Further research is needed to know the potential effects of this ostracod species on the ecology of P. clarkii and of native species, with implications on the management of this aquatic invader.

Mutual Climatic Range Methods for Quaternary Ostracods

Abstract The development of Mutual Climatic Range (MCR) methods for ostracods has included the estimation of marine bottom-water palaeotemperatures, but it has focused mainly on the use of non-marine ostracods to infer past air temperatures. The Delorme analogue MCR method, using only those components of a fossil assemblage that co-exist today, has yielded mean annual air temperature and annual precipitation estimates for North American Quaternary sites. The Mutual Ostracod Temperature Range (MOTR) non-analogue MCR method utilises all species in a fossil assemblage; calibrations based on a European database have been applied to the estimation of mean July and January air temperatures for English Pleistocene sites. These approaches are reviewed and their relative merits discussed; both yield results comparable to those of other proxies such as the beetle MCR method. A revised calibration table for European non-marine ostracods is provided, and new MOTR estimates for English glacial and interglacial sites are presented.

Ostracod palaeolimnological analysis reveals drastic historical changes in salinity, eutrophication and biodiversity loss in a coastal Mediterranean lake

The Albufera of Valencia, one of the largest oligohaline coastal lagoons of the Iberian Peninsula, has suffered hydrological and landscape modifications since medieval times. This paleolimnological study clears up the controversy about the factors, which drove the lake to its present state. Lithological descriptions, ostracod paleoassemblages and Cyprideis torosa (Jones, 1850) shell morphological variations and geochemistry (δ18O, δ13C and Sr/Ca) have been used to reconstruct the lake ecosystem evolution during the last two centuries. The sandy sediments at the bottom of L’Antina core (63 cm) presented a typical assemblage of brackish water ostracods, with shell-derived δ18O values, inferred salinity and Sr/Ca water characteristic of waters with marine influence. However, 10 cm above, coinciding with a drastic change in lithology, ostracod palaeoassemblages and decreased shell δ18O indicated a shift to freshwater influences. At the top of the sequence, inferred salinity suggests oligohaline waters and ostracods have almost disappeared. The early brackish conditions of Lake Albufera changed at the beginning of the 19th century when important hydrological modifications were undertaken for irrigation and started the major period of rice field expansion. Later, with the change of traditional rice farming to a more technological agriculture, together with increased domestic and industrial sewage inputs, the Albufera became a highly eutrophicated system 50 years ago. Eventually, the loss of macrophyte cover, cyanobacteria blooms and the increase of grazing by fish forced the loss of ostracod communities, currently almost inexistent.

Global distribution of Fabaeformiscandona subacuta: an exotic invasive Ostracoda on the Iberian Peninsula?

Although exotic species of Ostracoda have been recorded from various sites in Europe, none of them have a widespread European distribution. Reviews of existing literature, examination of specimens, and sampling in Spain and Japan has greatly expanded the known distribution of the candonid ostracode Fabaeformiscandona subacuta (Yang, 1982). We herein present new reports of its presence in mainland eastern Asia, Australia, and South America, and we review its distribution on the Iberian Peninsula. Although this species is globally widespread, we hypothesize that it is an invasive species on the Iberian Peninsula in light of the following facts: it is not known from other European countries, its known global distribution is extremely disjunct, it has not been found during palaeo-limnological investigations of European lakes, and on the Iberian Peninsula it is almost exclusively found in artificial, intensely human-impacted habitats, mostly in reservoirs and ricefields.

Breaking the temperature-size rule: thermal effects on growth, development and fecundity of a crustacean from temporary waters.

The temperature-size rule (TSR) is a well-established phenomenon to describe the growth response of ectotherms to temperature by which individuals maintained at low temperatures grow more slowly, but attain a larger size upon maturity. Although there are adaptive and non-adaptive theories about the plasticity of body size in response to temperature, these cannot be applied to all ectotherms, and little is known about the changes in growth and development rates through ontogeny. The ostracod species Heterocypris bosniaca, an inhabitant of freshwater temporary ponds, was used to examine the growth and development rates of its nine growth stages and female fecundity at four different temperatures (15°C, 20°C, 25°C and 30°C). The development rate of this species accelerates with increasing temperature, reaching a maximum value at 25°C. The growth factor has a reverse-TSR in younger instars, and the typical TSR is followed only in the last two moults, resulting in non-monotonic response of adult size to temperature. Fecundity (total offspring per female) was not directly related to adult size and was generally higher at lower temperatures. Our results agree with recent research showing that the TSR may vary during ontogeny, and may not be a general trend in ostracod species from temporary waters. Indeed, adult carapace size seems to follow the pattern of a thermal reaction norm, probably influenced by the reduction of oxygen bioavailability at low temperature and the drastic increase in metabolic demand at the upper extreme of the thermal gradient.

Invasion biology in non-free-living species: interactions between abiotic (climatic) and biotic (host availability) factors in geographical space in crayfish commensals (Ostracoda, Entocytheridae)

In invasion processes, both abiotic and biotic factors are considered essential, but the latter are usually disregarded when modeling the potential spread of exotic species. In the framework of set theory, interactions between biotic (B), abiotic (A), and movement-related (M) factors in the geographical space can be hypothesized with BAM diagrams and tested using ecological niche models (ENMs) to estimate A and B areas. The main aim of our survey was to evaluate the interactions between abiotic (climatic) and biotic (host availability) factors in geographical space for exotic symbionts (i.e., non-free-living species), using ENM techniques combined with a BAM framework and using exotic Entocytheridae (Ostracoda) found in Europe as model organisms. We carried out an extensive survey to evaluate the distribution of entocytherids hosted by crayfish in Europe by checking 94 European localities and 12 crayfish species. Both exotic entocytherid species found, Ankylocythere sinuosa and Uncinocythere occidentalis, were widely distributed in W Europe living on the exotic crayfish species Procambarus clarkii and Pacifastacus leniusculus, respectively. No entocytherids were observed in the remaining crayfish species. The suitable area for A. sinuosa was mainly restricted by its own limitations to minimum temperatures in W and N Europe and precipitation seasonality in circum-Mediterranean areas. Uncinocythere occidentalis was mostly restricted by host availability in circum-Mediterranean regions due to limitations of P. leniusculus to higher precipitation seasonality and maximum temperatures. The combination of ENMs with set theory allows studying the invasive biology of symbionts and provides clues about biogeographic barriers due to abiotic or biotic factors limiting the expansion of the symbiont in different regions of the invasive range. The relative importance of abiotic and biotic factors on geographical space can then be assessed and applied in conservation plans. This approach can also be implemented in other systems where the target species is closely interacting with other taxa.

Quantitative Transfer Function Approaches in Palaeoclimatic Reconstruction Using Quaternary Ostracods

Abstract Quantifying (palaeo-)environmental changes is a key challenge for aquatic biological proxies, but the number of published transfer functions is increasing rapidly for the main palaeoecologically relevant groups such as diatoms and chironomids, and several transfer functions have also been developed during the past decades based on ostracod findings. The main environmental variables influencing the species assemblage composition in ostracod training sets are specific ion concentrations or ratios, salinity, water temperature and/or water depth. The available transfer functions and training sets are globally scattered, but often regionally restricted in their application. The most common numerical methods in ostracod transfer functions are weighted averaging and weighted averaging partial least squares regression and calibration. Here, we discuss the specific prerequisites to set up new datasets for ostracods and review available transfer functions and their interpretation.

Rice fields as facilitators of freshwater invasions in protected wetlands: the case of Ostracoda (Crustacea) in the Albufera Natural Park (E Spain)

BackgroundPrevious studies have identified rice fields in the Mediterranean region as ‘hot spots’ for the introduction of alien freshwater organisms. Consequently, special attention should be paid when rice fields are located inside or near protected areas for the conservation of native, endangered species. To analyse the relationship between rice field environmental traits and the ecology of aquatic invaders, a study of zoobenthic communities was carried out in July-September 2008 and May-August 2009 in ten rice fields located in the Albufera Natural Park (E Spain), with focus on Ostracoda.ResultsA total of nine ostracod species were found including four considered exotic: Candonocypris novaezelandiae, Stenocypris macedonica, Cypris subglobosa and Hemicypris barbadensis. The presence of H. barbadensis is remarkable, which is recorded for the first time in Europe and S. macedonica in the Iberian Peninsula. A checklist of Ostracoda from Albufera Natural Park is presented, including 11 exotic species, mostly unknown from Holocene sedimentary records. The analysis of ostracod assemblages showed a significant relationship between oxygen content and ostracod species associations, suggesting that their abundance are partially controlled by habitat variables in the rice fields. The exotic species C. novaezelandiae was more abundantly collected in samples with reduced oxygen concentrations, in contrast to other native species whose abundances were lower in such conditions.ConclusionsRice fields in Mediterranean areas present a summer inundation period which is unlikely in natural temporary water bodies in the area and which may facilitate invasion by (sub-)tropical species. Lower proportion of exotic to native ostracods is observed in less disturbed areas compared to rice fields with intense human activities. We emphasize the role of anthropogenic effects in the dispersal and colonization processes of exotic ostracods and their particular strong influence in the protected areas closest to rice fields.

Different Scales of Spatial Segregation of Two Species of Feather Mites on the Wings of a Passerine Bird

Abstract The “condition-specific competition hypothesis” proposes that coexistence of 2 species is possible when spatial or temporal variations in environmental conditions exist and each species responds differently to those conditions. The distribution of different species of feather mites on their hosts is known to be affected by intrinsic host factors such as structure of feathers and friction among feathers during flight, but there is also evidence that external factors such as humidity and temperature can affect mite distribution. Some feather mites have the capacity to move through the plumage rather rapidly, and within-host variation in intensity of sunlight could be one of the cues involved in these active displacements. We analyzed both the within- and between-feather spatial distribution of 2 mite species, Trouessartia bifurcata and Dolichodectes edwardsi, that coexist in flight feathers of the moustached warbler Acrocephalus melanopogon. A complex spatial segregation between the 2 species was observed at 3 spatial levels, i.e., “feather surfaces,” “between feathers,” and “within feathers.” Despite certain overlapping distribution among feathers, T. bifurcata dominated proximal and medial regions on dorsal faces, while D. edwardsi preferred disto-ventral feather areas. An experiment to check the behavioral response of T. bifurcata to sunlight showed that mites responded to light exposure by approaching the feather bases and even leaving its dorsal face. Spatial heterogeneity across the 3 analyzed levels, together with response to light and other particular species adaptations, may have played a role in the coexistence and segregation of feather mites competing for space and food in passerine birds.