Assessing the effects of temperature and salinity oscillations on a key mesopredator fish from European coastal systems

Abstract A population dynamics model was developed to assess the short and long-term effects of temperature and salinity variations in the common goby Pomatoschistus microps in a Portuguese estuary (Minho estuary, NW Portugal). The population was divided into juveniles, females and males, which constituted the model’s state variables. Linear regressions between the observed and the predicted density of juveniles, females and the total population were significant. Parameter’s sensitivity and uncertainty analysis were estimated. The model was able to satisfactory describe the P. microps population dynamics, and thus was used to simulate the effects of climatic changes on the fish population. Simulations indicated that the common goby population is sensitive to both temperature and salinity changes. Overall, scenarios of + 4°C increase caused significant population decreases. Similarly, increased salinities led to a population shrinkage, whereas scenarios of salinity decrease generated an opposite variation on the population. According to the IPCC predictions for climatic tendencies, the population of the common goby will tend to decrease in the near future, experiencing marked oscillations (decrease or increase) during climatic extremes, namely droughts and floods, respectively. These results may be a useful tool for future planning and management of estuarine systems given that the common goby is an important species of estuarine food webs in many temperate ecosystems. Keywords: Population modelling, Pomatoschistus microps, climate change, uncertainty, estuary, Portuga

Spatio-temporal and intra-specific variations in the physiological and biochemical condition of the invasive bivalve Corbicula fluminea

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. Raw data will be available under reasonable request.Corbicula fluminea is a known aquatic invasive species responsible for several ecological and economic impacts. In Portugal, it is found in all major watersheds, although to varying degrees of invasion (regarding density, biomass and spatial distribution). The aim of this study was to evaluate the spatio-temporal differences in condition indices (CIs) and biochemical composition (proteins, lipids and energy) of individuals collected in Lima (low invasion) and Minho (high invasion) Rivers, as well as the effects of intra-specific competition (densities: 150, 500, 1000 individuals/m2) on the CIs of C. fluminea. CIs and biochemical composition varied between rivers and over time, with populations in Lima and Minho showing different patterns. Corbicula fluminea in Lima River had higher CIs and lower densities with more individuals of larger size, while individuals in Minho River had lower CIs and high densities with a more uniform size distribution. The intra-specific competition experiment showed that the optimum of C. fluminea was reached at 500 individuals/m2 density, possibly related to the species ability of enrich sediments with organic matter, leading to a positive feedback on phytoplankton and/or microbial communities. This study improves the understanding of the ecophysiological conditions of C. fluminea populations, a topic neglected in previous studies.This research was supported by national funds through FCT—Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDP/04423/2020. We thank Joana Nogueira for her help with the map of the study area

Influence of the asian clam Corbicula fluminea (bivalvia : corbiculidae) on estuarine epibenthic assemblages

Supplementary data related to this article can be found at: http:// dx.doi.org/10.1016/j.ecss.2014.03.017One of the most widespread invasive alien species (IAS) in aquatic ecosystems is the Asian clam Corbicula fluminea. Several studies have shown that C. fluminea can cause large-scale changes in macrozoobenthic assemblages; however, very few attempted to investigate the effects of this IAS on mobile epibenthic species, such as fishes and crustaceans. In this context, the influence of C. fluminea on epibenthic species was investigated during one year by comparing the associated epibenthic fauna in three nearby sites of the Minho estuary (NW of the Iberian Peninsula), wherein the abiotic conditions are similar but the density of the Asian clam is highly different. From a total of 13 species, six were significantly influenced by C. fluminea; five responded positively, namely the brown shrimp Crangon crangon, the European eel Anguilla anguilla, the common goby Pomatoschistus microps, the brown trout Salmo trutta fario and the great pipefish Syngnathus acus, whereas the shore crab Carcinus maenas was negatively influenced. However, stomach contents analysis revealed that fish and crustacean species do not feed on C. fluminea, suggesting that this IAS is still not a large component of the diet of higher trophic levels in this estuarine ecosystem. Our results suggest that the structure provided by C. fluminea shells is likely to be one of the main factors responsible for the differences observed. C. fluminea physical structure seems to influence the epibenthic associated fauna, when found in densities higher than 1000 ind./m2 , with sedentary small-bodied crustaceans and fishes being mainly attracted by the increasing in habitat complexity and consequent enhancement of heterogeneity and shelter availability.This study was part of the PhD thesis of the leading author and was financed by a grant from the Portuguese Foundation for Science and TechnologyeFCT (SFRH/BD/33387/2008). This work was partially supported by European Union Funds (FEDER/COMPETEe Operational Competitiveness Program) and by national funds ( FCT e Portuguese Foundation for Science and Technology) under the project ECO-IAS: Ecosystem-level impacts of an invasive alien species (PTDC/AAC-AMB/116685/2010). Currently Martina Ilarri is supported by a Post-doc grant from the FCT (SFRH/BPD/90088/ 2012). Special thanks to Eduardo Martins for field assistance, Fabiana Freitas for helping with the stomach contents analyses and Rute Pinto for helping with the map

Associated macrozoobenthos with the invasive Asian clam Corbicula fluminea

The Asian clam Corbicula fluminea is one of the most invasive species in brackish and freshwater ecosystems. In the Minho estuary (NW of the Iberian Peninsula) this invasive species can reach densities up to 4000 ind m−2, occurring over large areas. C. fluminea can significantly alter the physical structure of the benthic environment, and the structure and functioning of this estuarine community. In this context, this work aimed to evaluate the correlation of different densities of C. fluminea on the macrozoobenthos across five sites in the Minho estuary during three distinct periods of 2009 (winter, spring and summer). The comparative analysis indicate that macrozoobenthic density, biomass and diversity positively respond to increasing density of C. fluminea, with abiotic conditions also playing an important role in the observed patterns, both in brackish and freshwater settings. Crustacea, Insecta and Gastropoda are the main faunal groups responding positively to C. fluminea increasing density. The mechanisms responsible for these positive trends still needs to be established although engineering activities and the increase in waste products may play essential roles. Nevertheless, despite such positive effects, earlier studies have showed that the density, biomass and spatial distribution of some species, especially native bivalves dramatically decreased after C. fluminea introduction.Martina Ilarri is supported by a PhD. grant from Portuguese Foundation for Science and Technology — FCT (SFRH/BD/33387/ 2008).This work was partially funded by The Malacological Society of London.info:eu-repo/semantics/publishedVersio

Influence of temperature on intraspecific, unbalanced dyadic contests between crabs

Intraspecific agonistic interactions are widespread across the animal kingdom, with many individual morphological and physiological characteristics playing important roles in the fate of disputes. Additionally, changes to environmental conditions can influence the outcomes of animal contests. The shore crab (Carcinus maenas) is a globally distributed species, present in numerous coastal and estuarine temperate systems around the world. Although shore crabs are highly tolerant to changes in temperature, this parameter has important physiological effects on the species’ ecology, while its effects on behavior are not fully understood. Our study aims to investigate how different individual characteristics (such as sex, color morphotype, carapace and chela morphology) and temperature conditions affect the dyadic interactions between shore crabs when disputing food resources. In general, the differences in carapace width between opponents, their sexes, color morphotypes and the temperature conditions interacted and were important predictors of the contest fate. We found that the body size and color morphotype of C. maenas determined the fate of dyadic disputes. However, the higher temperatures disrupted the well-established dominance of the larger red color morphotype individuals. Overall, the agonistic contest results suggest higher plasticity than previously acknowledged

Non-random reef use by fishes at two dominant zones in a tropical, algal-dominated coastal reef

Habitat use and the processes which determine fish distribution were evaluated at the reef flat and reef crest zones of a tropical, algal-dominated reef. Our comparisons indicated significant differences in the majority of the evaluated environmental characteristics between zones. Also, significant differences in the abundances of twelve, from thirteen analyzed species, were observed within and between-sites. According to null models, non-random patterns of species co-occurrences were significant, suggesting that fish guilds in both zones were non-randomly structured. Unexpectedly, structural complexity negatively affected overall species richness, but had a major positive influence on highly site-attached species such as a damselfish. Depth and substrate composition, particularly macroalgae cover, were positive determinants for the fish assemblage structure in the studied reef, prevailing over factors such as structural complexity and live coral cover. Our results are conflicting with other studies carried out in coral-dominated reefs of the Caribbean and Pacific, therefore supporting the idea that the factors which may potentially influence reef fish composition are highly site-dependent and variable

Massive mortality of the Asian clam Corbicula fluminea in a highly invaded area

MI is supported by a PhD. grant from Portuguese Foundation for Science and Technology-FCT (SFRH/BD/33387/2008). Special thanks to Eduardo Martins for technical assistance and Jonathan Wilson for helpful English revision

Effects of tourist visitation and supplementary feeding on fish assemblage composition on a tropical reef in the Southwestern Atlantic

The effects of tourist visitation and food provisioning on fish assemblages were assessed by visual censuses (stationary technique) carried out in a tropical reef in Northeastern Brazil. Comparisons of species abundance, richness, equitability, and trophic structure in the presence (PT) and absence (AT) of tourists suggest that tourist visitation and supplementary food influenced the structure of the fish assemblage, as follows: (a) diversity, equitability and species richness were significantly higher on the AT period, while the abundance of a particular species was significantly higher during PT; (b) trophic structure differed between the AT and PT periods, omnivores being more abundant during the latter period, while mobile invertivores, piscivores, roving herbivores and territorial herbivores were significantly more abundant on AT. Reef tourism is increasingly being regarded as an alternative to generate income for human coastal communities in the tropics. Therefore, closer examination of the consequences of the various components of this activity to reef system is a necessary step to assist conservation and management initiatives