Brachidontes Pharaonis Research Articles

ASPECTS OF REPRODUCTIVE BIOLOGY OF THE MUSSEL, BRACHIDONTES PHARAONIS (FISCHER, 1870) (MYTILIDAE:BIVALVIA: MOLLUSCA) FROM THE NORTHWESTERN COAST OF SUEZ GULF, EGYPT

Reproductive cycle of the two populations of Brachidontes pharaonis (Mytilidae: Bivalvia: Mollusca)at Adabia and Ain Sokhna (northern western coast of the Suez Gulf), was studied during the period from January to December 2014. The present results showed that sex is separated in this species, but the microscopic examinations are necessary for determination of gonads in both sexes. The first appearance for gonads was observed in males and females at 6.3and 6.5 mm shell length, respectively. However, the largest immature individuals reach 8.6 mm shell length. The overall sex ratio indicated to over dominant females at both sites, with 1:1.57 (males: females) at Adabia, increased slightly to 1:1.81 (males: females) at Ain Sokhna, with statistical significant differences (X2= 8.33 and 5.14 significant at P

The gametogenic cycle and spawning of the mussel Brachidontes pharaonis (Fischer, 1876) (Bivalvia: Mytilidae) from Alexandria Coast, Egypt

The reproductive cycle and sexuality studies of the mussel Brachidontes pharaonis were carried out during the period from March 2016 to February 2017 along Alexandria Coast, Egypt. The gametogenic development of the gonads and the spawning duration under natural conditions were also studied. Histological preparations of a total of 307 individuals were examined monthly and the results showed that 44% were males, 51.8% females, 3.9% were sexually undifferentiated individuals and only one individual was hermaphrodite presenting 0.33% of the examined population, which indicates that B. pharaonis is gonochoristic. Histological studies showed that the gametogenic cycle could be divided into five stages of maturation. Also, an extended period of spawning starting from April to October was detected. Spawning activity of the studied species was in May to July and October. Gonad index reached its maximum in May, August and October when most of the individuals were in ripe and spawning activity. Sexes were distinct all over the studied size classes except those individuals in resting condition (stage 0). The smallest ripe gonads of both sexes were observed at 8.0–12.0 mm shell lengths. Photomicrographs of gametogenic cycles of both male and female mussels are included.

Relationships between plastic litter and chemical pollutants on benthic biodiversity

Five Descriptors (D) of Marine Strategy Framework Directive (MSFD): marine litter (D10), non-indigenous species (D2) and organic and inorganic pollutants (D8), were estimated in a coastal area of GSA 16 (Augusta harbour, Central Mediterranean Sea) in order to study their effects on the biodiversity (D1) of the benthic community D6) and to improve data for the MSFD. Investigation of plastic debris had led to the identification of 38 fragments divided into four categories, among which microplastics resulted as the most abundant. Six non-indigenous species, belonging to Polychaeta (Kirkegaardia dorsobranchialis, Notomastus aberans, Pista unibranchia, Pseudonereis anomala, Branchiomma bairdi) and Mollusca (Brachidontes pharaonis) were found. Biodiversity and benthic indices suggested a generalised, slightly disturbed ecological status. Anthracene, Zinc and Chrome were the most abundant chemical compounds in analysed sediments. Significant correlations were found between the abundance of trace elements vs biotic indices and between plastic debris vs biodiversity and benthic indices. This study represents the first report about the abundance of plastic debris and its relationship to contaminants and infauna in Augusta harbour. Our results can provide useful information for national and international laws and directives.

Genetic variability of the Lessepsian migrant mussel Brachidontes pharaonis (Bivalvia: Mytilidae) in Tunisia

The present study used two mitochondrial markers (16S rRNA and COI) to assess the genetic diversity of a newly founded Lessepsian migrant mussel, Brachidontes pharaonis, in Tunisian waters. The species appears to be restricted to only one population in Rades Harbour, in the northern part of the country. Phylogenetic analyses revealed the monophyly of B. pharaonis in Tunisia. Both molecular markers revealed high genetic variability of the B. pharaonis population. Haplotype networks and demographic analyses confirmed the recent expansion events within this population. Multiple human-mediated introduction events involving several founder populations and intensive population growth rates are probably the main causes of the high polymorphism observed within this invasive mollusc.

Multiple stressors facilitate the spread of a non‐indigenous bivalve in the Mediterranean Sea

AbstractAimThe introduction of non‐indigenous species (NIS) via man‐made corridors connecting previously disparate oceanic regions is increasing globally. However, the environmental and anthropogenic factors facilitating invasion dynamics and their interactions are still largely unknown. This study compiles and inputs available data for the NIS bivalve Brachidontes pharaonis across the invaded biogeographic range in the Mediterranean basin into a species distribution model to predict future spread under a range of marine scenarios.LocationMediterranean Sea.MethodsA systematic review produced the largest presence database ever assembled to inform the selection of biological, chemical and physical factors linked to the spread of B. pharaonis through the Suez Canal. We carried out a sensitivity analysis to simulate current and future trophic and salinity scenarios. A species distribution model was run to determine key drivers of invasion, quantify interactive impacts arising from a range of trophic states, salinity conditions and climatic scenarios and forecast future trajectories for the spread of NIS into new regions under multiple‐parameter scenarios (based on the main factors identified from the systematic review).ResultsImpacts on invasion trajectory arising from climate change and interactions with increasing salinity from the new opening of the canal were the primary drivers of expansion across the basin, the effects of which were further enhanced by eutrophication. Predictions of the current distribution were most accurate when multiple stressors were used to drive the model. A habitat suitability index developed at a subcontinental scale from model outputs identified novel favourable conditions for future colonization at specific locations under 2030 and 2050 climatic scenarios.Main conclusionsFuture expansion of B. pharaonis will be enhanced by climate‐facilitated increased sea temperature, interacting with increasing pressures from salinity and eutrophication. The spatially explicit risk output maps of invasions represent a powerful visual product for use in communication of the spread of NIS and decision‐support tools for scientists and policymakers. The suggested approach, the observed distribution pattern and driving processes can be applied to other NIS species and regions by providing novel forecasts of species occurrences under future multiple stressor scenarios and the location of suitable recipient habitats with respect to anthropogenic and environmental parameters.

Hermaphroditism in Brachidontes pharaonis (Fischer, 1876) (Bivalvia: Mytilidae) from the Alexandria Coast, Egypt

Brachidontes pharaonis (Fischer, 1876) was widely reported to cover completely hard substrates especially rocky shores with higher density in mid-littoral zones forming mytilid beds along Alexandria Coast, Egypt. During our study on the reproductive cycle of this species, one case out of 307 examined specimens was found to be hermaphrodite representing only 0.33% of the total sample. It had a shell length 28.25 mm and was collected during January 2017. The sex ratio of this population is different from 1:1, although this deference was not significant (X2 = 11.118, df = 11, P > 0.05). In this contribution, this case of hermaphroditism in B. pharaonis is described. The histological study showed the presence of male and female gametes in the same follicle and this was the most common situation in both lobes of the mantle. The male zone was showing different stages of spermatogenesis together with the female zones showed different stages of oogenesis with occurrence of young oocytes attached to the follicle wall.

Macro-Fouling Faunal Assemblage in Hambantota Port

Invasive species recognized as one of the greatest threats to global biodiversity and biofouling on submerged structures within a port environments is one of the major pathways of invasions by Non Indigenous Species (NIS). Early detection and monitoring of such deleterious organisms is crucial, since control is nearly impossible once established. The present work is a baseline study for biofouling faunal assemblage in Hambantota Port. The study consisted of two stages; initial sampling for investigating existing biofouling assemblage and review sampling after 10 months in order to monitor the changes in community structure. Sampling followed an international protocol developed by Center for Research on Introduced Marine Pest (CRIMP). Samples were scraped from submerged hard substrata in 12 sampling sites with the assistance from divers. Organisms in scraped samples were identified to the nearest taxonomic level using taxonomic guides and databases. All together 90 species were recorded during the study. Among them, 72 species were recorded within the baseline sampling and additional 18 during review sampling. Highest number of species recorded from phylum Mollusca (54) followed by Arthropoda (11), Annelida (11), Chordata (5), Cnidaria (4),Echinodermata (3) and Bryozoa (2). Balanus amphitrite, Balanus tintinnabulum, were the most common species in baseline sampling while Chthamalus sp.1 and Cellana radiata in the review sampling. Balanus tintinnabulum, Clypidina notata, Cellana radiata, Thais echinata, Harmoniconus parvatus and Saccostrea cucullata were the common species found in both sampling. In baseline sampling, highest number of species was recorded from Oil Pier (31) while least number (1) was recorded in the outer harbour artificial island. In review sampling, highest species richness (12) recorded in west bank while least species richness (5) was recorded within the West Breakwater. The most noteworthy finding is that eight globally known invasive species which include, Rapana venosa, Phallusia nigra, Perna perna, Brachidontes pharaonis, Balanus amphitrite, Balanus reticulates, Balanus trigonus and Schizoporella errata were recorded. Among them Rapana venosa was recorded only in review sampling and rest in baseline sampling. Keywords: Biofouling, Non-indigenous species, Baseline study, Hambantota Port

“New Mediterranean Biodiversity Records” (March 2017)

This Collective Article presents information on 22 species belonging to 5 Phyla, arranged geographically from from west to east. The new records were found in 8 countries as follows: Spain: first record of the two scarcely known nemerteans Baseodiscus delineatus and Notospermus geniculatus in Formentera; Malta: second record of the alien fish Lagocephalus sceleratus; Italy: the alien polychaete Syllis pectinans and the isopod Paranthura japonica, as well as the cryptogenic opisthobranch Anteaeolidiella lurana, were found in the fouling assemblages along the docks of the port of Livorno. New decapod records are reported from Sicily (the alien Callinectes sapidus and the native Pachygrapsus maurus) and Apulia (Percnon gibbosus and Procambarus clarkii); the lesser amberjack Seriola fasciata extended its geographical range to the Egadi Isands and Siganus luridus was documented for the first time along the Ionian coasts of Apulia and Calabria. Slovenia: the first record of the alien bivalve Brachidontes pharaonis is reported, together with a survey of up to date Adriatic records. Greece: the first record of the gastropod Rhinoclavis kochi is reported from Gavdos island. In addition, two records of endangered and rare cartilaginous fish were reported, namely, the shark Hexanchus griseus and the ray Leucoraja fullonica, as well as additional records of Siganus luridus for Lesvos and Malleus regula and Fulvia fragilis from Astypalaia. Turkey: the black wing flyingfish Hirundichthys rondeletii is reported for the very first time from the Black Sea. Egypt: the Indo-Pacific crab Halimede ochtodes is reported as established in Port Said. In addition, biometric parameters and meristic counts are reported for Anthias anthias in Damietta. Cyprus: the alien opisthobranch gastropod Bursatella leachii is reported for first time.

Functional and energetic consequences of climate change on a predatory whelk

The increasing rise in sea surface temperature caused by human activities currently represents the major threat to biodiversity and natural food webs. In this study we used the Lessepsian mussel Brachidontes pharaonis, one of the most recent invaders of the Mediterranean Sea, as a model to investigate the effect of a novel prey and a chronic increase in temperatures on functional parameters of local consumers, compared to the native mytilid species Mytilaster minimus. In particular we focused on the whelk Stramonita haemastoma, a widespread Mediterranean intertidal predator that actively preys on bivalves, barnacles and limpets, by studying the direct effects of such multiple stressors on feeding and growth rate, projected into a future climate change scenario (RCP8.5) relative to 2046–2065 with higher hypothesized temperatures of 2 °C. Gastropods showed a significantly higher feeding rate (ADFR) on M. minimus at high (6.45 ± 0.43) vs low temperatures (5.15 ± 0.33) compared to B. pharaonis (2.84 ± 0.37 vs 2.48 ± 0.27). Ingestion rate (ADIR), however, recorded higher values for B. pharaonis at high (1.71 ± 0.22) and low (1.49 ± 0.16) temperatures, compared to M. minimus (0.17 ± 0.01 vs 0.14 ± 0.01). Prey significantly influenced growth rate, condition index and the length-weight relationship (LWR) of whelks, while only ADFR seemed to be influenced by higher temperatures. In conclusion the extra amount of energy from the novel prey, together with temperature side effects, successfully influenced growth rates and reproductive events, positively affecting the global fitness of whelks.

Macrobenthic fauna associated with the invasive alien species Brachidontes pharaonis (Mollusca: Bivalvia) in the Levantine Sea (Turkey)

The invasive alien mytilid species, Brachidontes pharaonis, forms a biogenic habitat in the mediolittoral and upper-infralittoral zones of the Levantine Sea, hosting a number of alien and native species. Examinations of samples taken from dense, continuous mussel beds at seven stations along the coast of northern Levantine Sea yielded 187 macro-benthic invertebrate species belonging to 11 taxonomic groups. Polychaeta accounted for 46% and 37% of the total number of species and individuals, respectively. The top three dominant species in the mussel beds were Stenothoe gallensis, Spirobranchus kraussi and Mytilaster minimus. The species with the highest frequency values on the mussel beds were Pseudonereis anomala, Phascolosoma stephensoni and Elasmopus pocillimanus. The highest density and biomass of the associated fauna were estimated as 42,550 ind m−2 and 1503 wwt g m−2, respectively. The species number in samples varied between 14 and 47 species. The environmental variables best explaining variations in zoobenthic community structures were salinity, dissolved oxygen and total inorganic nitrogen in the water column. The biotic indices, TUBI and ALEX, classified the ecological status of one or two stations as moderate or poor, based on the relative abundances of ecological and zoogeographic groups, respectively. A total of 21 alien species were found to be associated with the mussel bed, of which Syllis ergeni is being newly considered as a new established alien species for the Mediterranean Sea. The maximum density of associated alien species was calculated as 30,300 ind m−2. The alien species assemblages were greatly affected by salinity and total inorganic nitrogen.

Erratum to: Biochemical biomarker responses to pollution in selected sentinel organisms across the Eastern Mediterranean and the Black Sea

Pollution effects were assessed by means of biochemical biomarkers (catalase, glutathione S-transferase and acetylcholinesterase activities, and metallothioneins content) in five species at selected coastal sites across the Eastern Mediterranean and the Black Sea. The mussel Mytilus galloprovincialis, a well-established sentinel species, was investigated in the Adriatic Sea, Aegean Sea, and Black Sea. The mussel Brachidontes pharaonis and the striped red mullet Mullus surmuletus were used in the Levantine Sea where M. galloprovincialis is not present. The white seabream Diplodus sargus sargus and the gastropod Rapana venosa were additionally sampled in the Adriatic and the Black Sea, respectively. Mussels showed catalase, glutathione S-transferase, and acetylcholinesterase responses to pollution in most geographical areas while the response of metallothioneins was restricted to a few sites. R. venosa showed marked responses of catalase and metallothioneins whereas both fish species did not generally exhibit variations in biomarker values among sites. The approach based on the reference deviation concept using the "Integrated Biological Responses version 2" index was useful for the interpretation of overall biomarker responses.

Biometric Relationships for the Bivalve Mussel, Brachidontes pharaonis Populations from the North-Western Coast of Suez Gulf, Egypt.

The biometric relationships for two populations of the bivalve mussel Brachidontes pharaonis collected monthly during the period from January 2014 to December 2014 from the intertidal zones of Adabia and Ain Sokhna coasts at the north-western portion of Suez Gulf were studied. The obtained results showed that there is a good relation between length and total body weight represented by allometric regression coefficients (b) being 2.112 and 2.376 for Adabia and Ain Sokhna populations, respectively. The overall value for relative condition factor “kn” varied from 0.83 to 1.22 and from 0.67 to 1.41 and averaged 1.01±0.13 and 1.02±0.22 for the two populations at Adabia and Ain Sokhna, respectively. These values denote to good well-being or fitness, but were not stable between different size classes; being higher in smaller individuals at size class 2.5 mm but decreased in the following size classes between 5 and 12.5 mm, and increased slightly again in the medium sized and larger individuals. The present results also showed that, the relations between both length and breadth as well as between length against width were allometric with regression coefficients “b “values less than “1” and were represented by 0.66 and 0.74 for the two variables respectively, at Adabia, but increased slightly to 0.74 and 0.85 at Ain Sokhna. These data show that, available habitats and favorable conditions being better at Ain Sokhna than Adabia. The length frequency distribution for the whole populations at the two sites were represented by 5 size classes, denotes to population stability controlled by continuous nearly equal adding for juveniles and removal by different mortality rates.

Ecological assessment of a heavily human-stressed area in the Gulf of Milazzo, Central Mediterranean Sea: an integrated study of biological, physical and chemical indicators

Marine environmental disturbance can be assessed directly from physical and chemical parameters, or indirectly by the study of indicator species. In this study, an integrated approach to monitor the Gulf of Milazzo, labeled as a highly contaminated site, is presented. A total of 83 samples were collected from hard and soft bottoms in 2010. In sum, 2739 specimens belonging to 246 taxa, two first records for the Tyrrhenian Sea (Micronephthys stammeri and Nicomache lumbricalis) and three nonindigenous species (Brachidontes pharaonis, Crassostrea gigas and Notomastus aberans) were recorded. Biodiversity and biotic indices and their relationship with sediment parameters and the level of pollutants were assessed to describe faunal assemblage and evaluate environmental quality. Pearson tests evidenced significant negative correlation between polychlorinated biphenyls (PCBs) and specific richness (p<0.10). A comparison of the standard and recorded biotic values showed that M-AMBI seems to be the index more representative of ecological quality status (EcoQ) in the Gulf of Milazzo. No evident signs were highlighted on the complex.

Local consumers are the first line to control biological invasions: a case of study with the whelk Stramonita haemastoma (Gastropoda: Muricidae)

The increasing spread of invasive species in the Mediterranean Sea determines several alterations in local food webs, changing the feeding habits of native organisms. The whelk Stramonita haemastoma is a widespread Mediterranean gastropod that consumes bivalves, barnacles and limpets. Previous studies showed a shift in its diet from the bivalve Mytilaster minimus to the invasive mussel Brachidontes pharaonis, presumably due to a higher energy gain. Here we tested whelks’ preference among natives and a novel prey, calculating the profitability ratio, and integrating those results with biochemical analysis on prey tissues and the routine metabolism of the whelks. Further, we used the scaled functional response as a theoretical tool to describe whelk ability to obtain energy from their environment by using four different prey species: B. pharaonis, Mytilus galloprovincialis, M. minimus and Patella caerulea. Whelks evidenced a Type II functional response for all prey, while Brachidontes displayed a lower attack rate and a higher handling time. Stramonita showed a greater preference for Brachidontes, that resulted as the prey with the higher energetic content, and the second most profitable after Patella. This suggests that the higher energy gain is behind the change in the predator’s diet, with possible effects on its energy budget.

Biochemical biomarker responses to pollution in selected sentinel organisms across the Eastern Mediterranean and the Black Sea.

Pollution effects were assessed by means of biochemical biomarkers (catalase, glutathione S-transferase and acetylcholinesterase activities, and metallothioneins content) in five species at selected coastal sites across the Eastern Mediterranean and the Black Sea. The mussel Mytilus galloprovincialis, a well-established sentinel species, was investigated in the Adriatic Sea, Aegean Sea, and Black Sea. The mussel Brachidontes pharaonis and the striped red mullet Mullus surmuletus were used in the Levantine Sea where M. galloprovincialis is not present. The white seabream Diplodus sargus sargus and the gastropod Rapana venosa were additionally sampled in the Adriatic and the Black Sea, respectively. Mussels showed catalase, glutathione S-transferase, and acetylcholinesterase responses to pollution in most geographical areas while the response of metallothioneins was restricted to a few sites. R. venosa showed marked responses of catalase and metallothioneins whereas both fish species did not generally exhibit variations in biomarker values among sites. The approach based on the reference deviation concept using the "Integrated Biological Responses version 2" index was useful for the interpretation of overall biomarker responses.

Life history traits to predict biogeographic species distributions in bivalves.

Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provided to test model performance in predicting the bivalve distribution throughout the 22 sites in the Central Mediterranean Sea under local conditions of food density and body temperature. Model skill and stationarity were tested through the estimate of commission (i.e., proportion of species' absences predicted present) and omission (i.e., proportion of presences predicted absent) errors of predictions by comparing mechanistic predicted vs. observed F and BS values throughout the study area extrapolated by lab experiments and literature search. The resulting relationship was reliable for both species, and body size and fecundity were highly correlated in M. galloprovincialis compared to B. pharaonis; FT-DEB showed correct predictions of presence in more than 75 % of sites, and the regression between BS predicted vs. observed was highly significant in both species. Whilst recognising the importance of biotic interactions in shaping the distribution of species, our FT-DEB approach provided reliable quantitative estimates of where our species had sufficient F to support local populations or suggesting reproductive failure. Mechanistically, estimating F and BS as key traits of species life history can also be addressed within a broader, scale-dependent context that surpasses the limitations related to correlative species distribution models.

Updated review of marine alien species and other ‘newcomers’ recorded from the Maltese Islands (Central Mediterranean)

An updated review of marine alien species and other ‘newcomers’ recorded from the Maltese Islands is presented on account of new records and amendments to a previous review in 2007. Species were classified according to their establishment status (‘Questionable’, ‘Casual’, ‘Established’, ‘Invasive’) and origin (‘Alien’, ‘Range expansion’, ‘Cryptogenic’). A total of 31 species were added to the inventory, while 6 species have been removed, bringing the total number of species to 73. Of these, 66 are considered to be aliens (or putative aliens but with uncertain origin) with the remaining 7 resulting from range expansion. Six records are considered to be questionable and hence unverified. For verified records, the dominant taxonomic groups are Mollusca (represented by 21 species) and Actinopterygii (15 species), followed by Crustacea (8 species) and Rhodophyta (7 species). Eight of these species (aliens: Caulerpa cylindracea, Lophocladia lallemandi, Womersleyella setacea, Brachidontes pharaonis, Percnon gibbesi, Fistularia commersonii, Siganus luridus; range extender: Sphoeroides pachygaster) are considered to be invasive. The introduction pathway for 30 species is unknown. Amongst the alien species, ‘Shipping’ is the most common introduction pathway, followed by ‘Secondary dispersal’ from elsewhere in the Mediterranean Sea. An increasing trend in the number of alien marine species reported from the Maltese Islands is evident, with a peak of 22 species recorded during the last decade (2001–2010). A discussion on the rationale for including range-expanding species in national inventories of recent arrivals, and in the analysis of trends in records from the Maltese Islands, is included. In particular, the general warming trend of Mediterranean surface waters appears to be facilitating the westward spread of thermophilic alien species from the Eastern to the Central Mediterranean, and the eastward range expansion of tropical and subtropical Eastern Atlantic species.

Dynamic energy budget parameterisation of Brachidontes pharaonis, a Lessepsian bivalve in the Mediterranean Sea

Dynamic Energy Budget (DEB) models are used for describing the flow of energy through organisms. The most important and powerful aspect of DEB theory is that inter-specific differences can be captured in the same model by comparison of parameter values. However, estimation of these parameters is complicated and can often not be done with direct empirical measurements alone. Here, we present DEB parameter estimates obtained by combining both experimental and literature data for the filter feeder Brachidontes pharaonis, which is considered one among the 100 worst invasive marine species in the Mediterranean Basin. We utilize a statistical procedure based on the covariation method to obtain parameters that minimize the deviation between observed and predicted patterns of growth and reproduction.

Parameterisation of bivalve functional traits for mechanistic eco-physiological dynamic energy budget (DEB) models

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 480:99-117 (2013) - DOI: https://doi.org/10.3354/meps10195 Parameterisation of bivalve functional traits for mechanistic eco-physiological dynamic energy budget (DEB) models G. Sarà1,*, V. Palmeri1, V. Montalto1, A. Rinaldi1,2, J. Widdows3 1Dipartimento di Scienze della Terra e del Mare, University of Palermo, Viale delle Scienze Ed. 16, 90128 Palermo, Italy 2Dipartimento di Scienze Biologiche ed Ambientali, University of Messina, Salita Sperone 31, 98166 Messina, Italy 3Plymouth Marine Laboratory, Prospect Place, Plymouth PL1 3DH, UK *Email: gianluca.sara@unipa.it ABSTRACT: Mechanistic models such as those based on dynamic energy budget (DEB) theory are emergent ecomechanics tools to investigate the extent of fitness in organisms through changes in life history traits as explained by bioenergetic principles. The rapid growth in interest around this approach originates from the mechanistic characteristics of DEB, which are based on a number of rules dictating the use of mass and energy flow through organisms. One apparent bottleneck in DEB applications comes from the estimations of DEB parameters which are based on mathematical and statistical methods (covariation method). The parameterisation process begins with the knowledge of some functional traits of a target organism (e.g. embryo, sexual maturity and ultimate body size, feeding and assimilation rates, maintenance costs), identified from the literature or laboratory experiments. However, considering the prominent role of the mechanistic approach in ecology, the reduction of possible uncertainties is an important objective. We propose a revaluation of the laboratory procedures commonly used in ecological studies to estimate DEB parameters in marine bivalves. Our experimental organism was Brachidontes pharaonis. We supported our proposal with a validation exercise which compared life history traits as obtained by DEBs (implemented with parameters obtained using classical laboratory methods) with the actual set of species traits obtained in the field. Correspondence between the 2 approaches was very high (>95%) with respect to estimating both size and fitness. Our results demonstrate a good agreement between field data and model output for the effect of temperature and food density on age–size curve, maximum body size and total gamete production per life span. The mechanistic approach is a promising method of providing accurate predictions in a world that is under increasing anthropogenic pressure. KEY WORDS: Mechanistic models · Dynamic energy budget · Bivalve · Parameterisation methods · Brachidontes pharaonis · Mediterranean Sea Full text in pdf format PreviousNextCite this article as: Sarà G, Palmeri V, Montalto V, Rinaldi A, Widdows J (2013) Parameterisation of bivalve functional traits for mechanistic eco-physiological dynamic energy budget (DEB) models. Mar Ecol Prog Ser 480:99-117. https://doi.org/10.3354/meps10195 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 480. Online publication date: April 22, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Eco-physiological response of two marine bivalves to acute exposition to commercial Bt-based pesticide

Microbial products based on the entomopathogenic bacterium Bacillus thuringiensis (Bt) are among the most common biopesticides used worldwide to suppress insect pests in forests, horticulture and agricultural crops. Some of the effects of commercial Bt have been recorded for terrestrial and freshwater non-target organisms but little research is available on marine fauna. Nevertheless, due to the contiguity of agro-ecosystems and coastal habitats, marine fauna may be highly influenced by this control method. We studied the effect of a commercial Bt product on the physiological and ecological responses and the energy budget of two of the most frequent marine intertidal bivalves in the Mediterranean, the native Mytilaster minimus and the invasive Brachidontes pharaonis. To test the effects experimentally, we simulated the worst scenarios possible using the average dose applied to fields and a hypothetical accumulation dose. The results showed the feeding rates of both species were affected detrimentally by the different experimental conditions; higher concentrations led to higher respiration rates, however neither species showed any significant difference in excretion rates. The biopesticide had a significant effect on the energy budget, the values decreasing with doses. In addition, it led to high mortality for the worst treatments and, in both species, induced significantly higher cardiac activity than in the controls. These results indicate a measurable effect of Bt commercial products on marine organisms, and great attention should be paid to biopesticides composed by entomopathogenic bacteria and addictive compounds. In addition, the results highlight the urgent need to study not only the effects of anthropogenic pressures on target organisms but also to extend our view to other ecosystems not expected to be influenced. Gaining data at the organismal level should help increase the sustainability of pest control and reduce the consequences of side-effects.