We investigated the influences of oceanographic variables on recruitment patterns of the acorn barnacle and the rock oyster , key space occupiers on tropical intertidal rocky shores. Recruitment data and nearshore environmental variables were obtained at spatial (regional and local) and temporal (monthly) scales on the west coast of Thailand. The relationship between the recruitment of each species and combinations of environmental variables was modeled. The climate of the study sites is influenced by the southwest and northeast monsoons of the Indochinese monsoon system. Observations showed that recruitment of both species and oceanographic variables exhibited differences at either local scale or monthly scale or both. Recruitment of both species was positively related to temperature, while barnacle recruitment was negatively related to salinity, but oyster recruitment was positively related to salinity. Barnacles showed a greater rate of recruitment when south-westerly onshore winds predominated during the southwest monsoon season, while the influence of wind patterns on rock oyster recruitment was not clear. Differential larval delivery regulated by monsoon-driven currents is, therefore, a potential determinant of barnacle recruitment. Our study highlights the roles of monsoon-influenced oceanographic processes as predictors of recruitment patterns of intertidal species in a tropical system.

Climate change is affecting the global hydrological cycle, causing drastic changes in precipitation patterns. Extreme climatic events are becoming more frequent and intense than in the past, leading to water-level fluctuations and affecting aquatic ecosystems. Semiarid regions are very susceptible to changing climate. We analyzed a 10 years dataset from a tropical semiarid reservoir during extreme hydrological events (heavy rains and prolonged drought), and evaluated phytoplankton functional responses to environmental conditions. We found, as hypothesized, that phytoplankton functional structure change in a temporal scale due to water-volume fluctuation induced by the rainfall pattern. Depth and inorganic material acted as environmental filters selecting phytoplankton groups. High water level seems to improve water quality and low water level worsen it. Colonial and filamentous cyanobacteria dominate the wet period; however, it may have a critical threshold during severe periods of drought, which will lead to dominance of groups well adapted to low light conditions and with mixotrophic metabolism. Phytoplankton functional approaches can simplify phytoplankton identification and reflect better the environmental conditions than the taxonomic approach. Therefore, these approaches can help to understand the shifts in aquatic ecosystems under extreme hydrological events and predict functional response of phytoplankton being an important tool to water management and conservation.

We summarized existing knowledge on (the zebra mussel) and (the quagga mussel), including data on their taxonomy, systematics, evolution, life cycle, reproduction, feeding, growth and longevity, population dynamics, interspecific competition, habitat requirements, and distribution within and among waterbodies. We analyzed the history of spread of both species and the major pathways and vectors of their spread in Europe and North America. Special consideration was given to their ecological and economic impacts and their natural enemies, like waterfowl, fishes, and parasites, as well as the prevention of their introduction, early detection, control, and containment. We also outlined the most salient ecosystem services provided by zebra and quagga mussels, including water purification, nutrient recycling, culling the effects of eutrophication, biomonitoring, and their role as a food resource for fish and waterfowl. Finally, we identified major knowledge gaps and key studies needed to better understand the biology, ecology, and impacts of these aggressive freshwater invaders. Our review indicates that much crucial information on the quagga mussel is still missing, including key life history parameters, like spawning cues, fecundity, and longevity, particularly for the profundal zone of deep lakes.

Very little is known about the feeding of naupliar and juvenile life stages of omnivorous fairy shrimps (Crustacea: Anostraca). Here, we aim to reveal whether the fairy shrimp is an ontogenetic omnivore and at which age and ontogenetic stage they gain the ability to feed on zooplankton. We assess how food uptake rates change with age until reaching maturity by providing algae (pico- and nanoplanktonic unicellular algae) and zooplankton (rotifers and copepod nauplii) as food in individual experiments. We found that the fairy shrimp started to feed on both types of algal prey immediately after hatching. Nanoplanktonic algae likely represented the most important food source until reaching maturity. Moreover, fairy shrimps started to feed on zooplankton already when they were 7 days old. Slow-moving rotifers gradually gained importance in the fairy shrimp diet with time. Our results reveal an ontogenetic change in the prey spectrum of fairy shrimp. The systematic shift towards omnivory likely affects both phyto- and zooplankton community composition, possibly contributing to temporal changes in food web dynamics in fairy shrimp habitats, and temporary ponds, which may warrant more detailed investigations in future studies.

Fish habitat associations are important measures for effective aquatic habitat management, but often vary over broad spatial and temporal scales, and are therefore challenging to measure comprehensively. We used a 9-year acoustic telemetry dataset to generate spatial-temporal habitat suitability models for seven fish species in an urban freshwater harbour, Toronto Harbour, Lake Ontario. Fishes generally occupied the more natural regions of Toronto Harbour most frequently. However, each species exhibited unique habitat associations and spatial-temporal interactions in their habitat use. For example, largemouth bass exhibited the most consistent seasonal habitat use, mainly associating with shallow, sheltered embayments with high aquatic vegetation (SAV) cover. Conversely, walleye seldom occupied Toronto Harbour in summer, with the highest occupancy of shallow, low-SAV habitats in the spring, which corresponds to their spawning period. Others, such as common carp, shifted between shallow summer and deeper winter habitats. Community level spatial-temporal habitat importance estimates were also generated, which can serve as an aggregate measure for habitat management. Acoustic telemetry provides novel opportunities to generate robust spatial-temporal fish habitat models based on wild fish behaviour, which are useful for the management of fish habitat from a fish species and community perspective.

In this review we highlight the relevance of biodiversity that inhabit coastal lagoons, emphasizing how species functions foster processes and services associated with this ecosystem. We identified 26 ecosystem services underpinned by ecological functions performed by bacteria and other microbial organisms, zooplankton, polychaetae worms, mollusks, macro-crustaceans, fishes, birds, and aquatic mammals. These groups present high functional redundancy but perform complementary functions that result in distinct ecosystem processes. Because coastal lagoons are located in the interface between freshwater, marine and terrestrial ecosystems, the ecosystem services provided by the biodiversity surpass the lagoon itself and benefit society in a wider spatial and historical context. The species loss in coastal lagoons due to multiple human-driven impacts affects the ecosystem functioning, influencing negatively the provision of all categories of services (i.e., supporting, regulating, provisioning and cultural). Because animals' assemblages have unequal spatial and temporal distribution in coastal lagoons, it is necessary to adopt ecosystem-level management plans to protect habitat heterogeneity and its biodiversity, ensuring the provision of services for human well-being to multi-actors in the coastal zone.

The taxonomic status of the zooplanktivorous cichlids and has been confused since their original descriptions by lles in 1960. Whilst two forms of , 'Kaduna' and 'Kajose', were distinguished in the type material, has not been positively identified since its original description. Here we re-examined the types as well as 54 recently collected specimens from multiple sampling locations. Genome sequencing of 51 recent specimens revealed two closely related but reciprocally monophyletic clades. Geometric morphological analysis indicated that one clade morphologically encompasses the type specimens of identified by Iles as the Kaduna form, including the holotype, whilst the other clade encompasses not only the paratypes identified as the Kajose form, but also the type series of . Given that all three forms in Iles's type series are from the same locality, that there are no meristic or character states to differentiate them and that there are no records of adult male in breeding colours, we conclude that the Kajose form previously identified as represents relatively deeper bodied sexually active or maturing individuals of .

The wide-ranging photic conditions found across aquatic habitats may act as selective pressures that potentially drive the rapid evolution and diversity of the visual system in teleost fish. Teleost fish fine-tune their visual sensitivities by regulating the two components of visual pigments, the opsin protein and the chromophore. Compared with opsin protein variation, chromophore usage across photic habitats has received little attention. The Nicaraguan Midas cichlid species complex, cf [Günther 1864], has independently colonized seven isolated crater lakes with different photic conditions, resulting in several recent adaptive radiations. Here, we investigate variation in , the main enzyme modulating chromophore exchange. We measured expression in photic environments in the wild, its genetic component in laboratory-reared fish, and its response to different light conditions during development. We found that photic environments significantly predict variation in expression in wild populations and that this variation seems to be genetically assimilated in two populations. Furthermore, light-induced expression exhibited genotype-by-environment interactions in our manipulative experiments. Overall, within-lake variation in expression was higher and inversely related to variation in opsin gene expression along the photic gradient, emphasizing the key role of in the visual ecology of cichlid fish.

Current evidence suggests that hybridization played a crucial role in the early evolution and diversification of the species flocks of cichlid fishes in the African Great Lakes. Nonetheless, evidence for hybridization in the extant cichlid fauna is scant, suggesting that hybridization is rare in the modern era, perhaps enforced by natural or sexual selection acting against F1 hybrids. Additionally, most experimental studies of hybridization perform a hybrid cross in one direction, ignoring the reciprocal hybrid. In this study, we perform reciprocal crosses between sympatric congeners from Lake Malaŵi, and , in order to compare the body shape and coloration of males of both of these hybrids, as well as to examine how these hybrids fare during both inter- and intrasexual interactions. We found that -sired hybrid males are intermediate to the parental species both morphologically and chromatically, while the reciprocal -sired hybrids are likely transgressive hybrids. Males of these transgressive hybrids also fare poorly during our mate choice experiments. While female reject them as possible mates, male do not make a distinction between them and conspecific males. Selection against transgressive F1 hybrids as observed in our crossing experiments may help explain why contemporary hybridization in Lake Malaŵi cichlids appears to be rare.

Currently, 50% of Irish rivers do not meet water quality standards, with many declining due to numerous pressures, including peatland degradation. This study examines stream water quality in the Irish midlands, a region where raised bogs have been all historically disturbed to various extent and the majority drained for industrial or domestic peat extraction. For the first time, we provide in-depth analysis of stream water chemistry within a heavily modified bog landscape. Small streams from degraded bogs exhibited greater levels of pollutants, in particular: total dissolved nitrogen (0.48 mg/l) and sulphate (18.49 mg/l) as well as higher electrical conductivity (mean: 334 μS/cm) compared to similar bog streams in near-natural bogs. Except for site-specific nitrogen pollution in certain streams surrounding degraded peatlands, the chemical composition of the receiving streams did not significantly differ between near-natural and degraded sites, reflecting the spatio-temporal scales of disturbance in this complex peat-scape. Dissolved organic carbon concentrations in all the receiving streams were high (27.2 mg/l) compared to other Irish streams, even within other peatland catchments. The region is experiencing overall a widespread loss of fluvial nitrogen and carbon calling for (a) the development of management instruments at site-level (water treatment) and landscape-level (rewetting) to assist with meeting water quality standards in the region, and (b) the routine monitoring of water chemistry as part of current and future peatland management activities.

Headwater streams harbor diverse macroinvertebrate communities and are hotspots for leaf litter breakdown. The process of leaf litter breakdown mediated by macroinvertebrates forms an important link between terrestrial and aquatic ecosystems. Yet, how the vegetation type in the local riparian zone influences leaf-associated macroinvertebrate assemblages and leaf litter breakdown rates is still not resolved. We investigated how leaf-associated macroinvertebrate assemblages and leaf litter fragmentation rates differ between forested and non-forested sites using experimental leaf litter bags in sixteen sites paired across eight headwater streams in Switzerland. Our results show that sensitive taxa of the invertebrate orders Ephemeroptera, Plecoptera and Trichoptera (EPT) and the functional group of shredders were strongly associated with forested sites with overall higher values of abundance, diversity, and biomass of EPTs in forested compared to non-forested sites. However, the importance of riparian vegetation differed between study regions, especially for shredders. Fragmentation rates, which are primarily the result of macroinvertebrate shredding, were on average three times higher in forested compared to non-forested sites. Our results demonstrate that not only the composition of the aquatic fauna but also the functioning of an essential ecosystem process depend on the vegetation type in the local riparian zone.

Fishponds, despite being globally abundant, have mainly been considered as food production sites and have received little scientific attention in terms of their ecological contributions to the surrounding terrestrial environment. Emergent insects from fishponds may be important contributors of lipids and essential fatty acids to terrestrial ecosystems. In this field study, we investigated nine eutrophic fishponds in Austria from June to September 2020 to examine how Chlorophyll- concentrations affect the biomass of emergent insect taxa (i.e., quantity of dietary subsidies;  = 108) and their total lipid and long-chain polyunsaturated fatty acid content (LC-PUFA, i.e., quality of dietary subsidies;  = 94). Chironomidae and Chaoboridae were the most abundant emergent insect taxa, followed by Trichoptera, Ephemeroptera, and Odonata. A total of 1068 kg of emergent insect dry mass were exported from these ponds (65.3 hectares). Chironomidae alone exported 103 kg of total lipids and 9.4 kg of omega-3 PUFA. Increasing Chl- concentrations were associated with decreasing biomass export and a decrease in total lipid and LC-PUFA export via emergent Chironomidae. The PUFA composition of emergent insect taxa differed significantly from dietary algae, suggesting selective PUFA retention by insects. The export of insect biomass from these eutrophic carp ponds was higher than that previously reported from oligotrophic lakes. However, lower biomass and diversity are exported from the fishponds compared to managed ponds. Nonetheless, our data suggest that fishponds provide crucial ecosystem services to terrestrial consumers by contributing essential dietary nutrients to consumer diets via emergent insects.

Sex-based differences in animal microbiota are increasingly recognized as of biological importance. While most animal biomass is found in aquatic ecosystems and many water-dwelling species are of high economic and ecological value, biological sex is rarely included as an explanatory variable in studies of the aquatic animal microbiota. In this opinion piece, we argue for greater consideration of host sex in studying the microbiota of aquatic animals, emphasizing the many advancements that this information could provide in the life sciences, from the evolution of sex to aquaculture.

The study of winter in temperate, ice-covered lakes has largely been neglected, creating a major gap in our understanding of annual phytoplankton cycles. We assessed patterns in biovolumes of cf. and total phytoplankton at three depths during the winter of 2014/2015 as estimated using images from an Imaging FlowCytobot (IFCB) moored in Lac (Lake) Montjoie, Quebec (Canada). Even though the use of the IFCB under-ice presented challenges, these were outstripped by its advantages. The IFCB provided unprecedented high temporal and spatial resolution phytoplankton count and biovolume data that allowed patterns of abundance to be observed in detail. Interestingly, the IFCB captured an abundance of , which may be dissolved in standard Lugol's-preserved grab samples. We found grew until mid-December and then slowly decreased towards the spring, whereas cf. diatoms decreased from early December and then rebounded towards late December as light increased before falling again towards the spring. peaked in late December as cf. diatoms rebounded and then began to decline towards the spring. Total phytoplankton declined towards late December, increased in the beginning of January and then declined towards the spring. The studied diatoms maintained considerable under-ice seed populations and grew when light was sufficient.

Native freshwater mussels (unionids) are indicators of water quality, with unique behaviors and movement patterns. Many of these species are endangered, yet basic movement and co-occurring community data are lacking for successful unionid conservation. In this study, movement, community, and habitat use among , an endangered unionid in Michigan, were analyzed across four rivers in central Michigan. The effects of sex, community, substrate use, and other abiotic factors on the movement and occurrence of were quantified. 24 individuals were found with variable male:female ratios and were monitored bi-weekly. Over the recapture period, moved an average minimum convex polygon of 1.43 m per day but was variable among rivers. 19 unionid species were found occurring with ; ~13 species in the same river reach as and ~5 species in closer proximity to . The tribe Lampsilini most often occurred in close proximity to . This study identified basic movement and occurrence patterns of and provides a better understanding of the status of in Michigan. Our study highlights useful methods in understanding imperiled unionids, expanding the knowledge of their movement, behavior, community assemblages, and habitat use.

Understanding and connecting the impact of anthropogenic activities on mangrove food webs is a research challenge. Has research on the subject been able to find answers using stable isotopes? The present opinion paper analyzed the utility of stable isotopes in tracing the impact of anthropogenic activities on mangrove food webs and if the research questions raised could be answered using these chemical markers. Representative research papers (16) focused on the use of stable isotopes (δC, δN, δS, δH, δD,206Pb/207Pb, and 208Pb/207Pb) to evaluate the effect of anthropogenic activities (Sewage discharge, timber harvesting-deforestation, metallurgical activities, hydrological disruption, aquaculture ponds, and urban development) on mangrove food webs were selected. Each article included at least one group of consumers (invertebrate or fish). Publications only focused on water quality or primary producers were not included. Most studies managed to determine the effect of the anthropogenic activities on the food web's stable isotope values. Based on the above, we concluded that these markers are an effective tool to determine affectation patterns on the structure and function of mangrove food webs. The results obtained herein facilitate the correct management of mangroves and their derived resources.

Variation in fin shape is one of the most prominent features of morphological diversity among fish. Regulation of fin growth has mainly been studied in zebrafish, and it is not clear whether the molecular mechanisms underlying shape variation are equally diverse or rather conserved across species. In the present study, expression levels of 37 candidate genes were tested for association with fin shape in the cichlid fish . The tested genes included members of a fin shape-associated gene regulatory network identified in a previous study and novel candidates selected within this study. Using both intact and regenerating fin tissue, we tested for expression differences between the elongated and the short regions of the spade-shaped caudal fin and identified 20 genes and transcription factors (including , , , , , , and ), whose expression patterns were consistent with a role in fin growth. Collated with available gene expression data of two other cichlid species, our study not only highlights several genes that were correlated with fin growth in all three species (e.g., , , , and ), but also reveals species-specific gene expression and correlation patterns, which indicate considerable divergence in the regulatory mechanisms of fin growth across cichlids.

For evaluating hydraulic stress reduction strategies of caddisfly larvae, our study has three goals. First, creating a database on Reynolds numbers () and drag coefficients valid for Limnephilidae larvae with cylindrical mineral cases. Second, evaluating the effects of submerged weight and biometry in cases with comparable length/width ratios. And third, collecting field data in an alpine environment for gaining insights into the hydraulic niches occupied by thirteen Drusinae species. Biometric data were subsequently combined with published Reynolds numbers and mean flow velocity data measured immediately upstream of Limnephilidae larvae at the moment of dislodgement. This provides drag coefficients for the range of Reynolds numbers obtained in the field. Data reveal that heavy cases strongly benefit from compensating drag by submerged weight, thereby enabling species to utilize high velocity spots, an important benefit for filtering species.

Mating patterns in animal populations can respond to environmental conditions and consequently vary across time. To examine this variation in nature, studies must include temporal replicates from the same population. Here, we report temporal variation in genetic parentage in the socially monogamous cichlid from Lake Tanganyika, using samples of broods and their brood-tending parents that were collected across five field trips from the same study population. The sampled broods were either spawned during the dry season (three field trips) or during the rainy season (two trips). In all seasons, we detected substantial rates of extra-pair paternity, which were ascribed to cuckoldry by bachelor males. Paternity shares of brood-tending males were consistently higher, and the numbers of sires per brood were consistently lower, in broods that were spawned in the dry seasons compared to broods from the rainy seasons. In contrast, the strength of size-assortative pairing in our population did not vary temporally. Seasonal fluctuations in environmental conditions, such as water turbidity, are proposed as a mechanism behind variable cuckolder pressure. Our data demonstrate the utility of long-term monitoring to improve our understanding of animal mating patterns.

Thermal stratification of reservoirs can lead to anaerobic conditions that facilitate the microbial conversion of mercury (Hg) to neurotoxic and bioaccumulative methylmercury (MeHg). But MeHg production is just the first step in a complex set of processes that affect MeHg in fish. Of particular relevance is uptake into suspended particulate matter (SPM) and zooplankton at the base of the pelagic food web. We assessed plankton dynamics and Hg uptake into the pelagic food web of four Hg-impaired California water reservoirs. Combining water chemistry, plankton taxonomy, and stable carbon (C) and nitrogen (N) isotope values of SPM and zooplankton samples, we investigated differences among the reservoirs that may contribute to differing patterns in MeHg bioaccumulation. Methylmercury accumulated in SPM during the spring and summer seasons. Percent MeHg (MeHg/Hg*100%) in SPM was negatively associated with δN values, suggesting that "fresh" algal biomass could support the production and bioaccumulation of MeHg. Zooplankton δC values were correlated with SPM δC values in the epilimnion, suggesting that zooplankton primarily feed in surface waters. However, zooplankton MeHg was poorly associated with MeHg in SPM. Our results demonstrate seasonal patterns in biological MeHg uptake and how multiple data sources can help constrain the drivers of MeHg bioaccumulation.

Biotic and abiotic factors that affect the physiology and ecology of scyphozoan polyps are considered to be major drivers of jellyfish blooms, but are rarely studied under field conditions. Here, stable isotopes of carbon and nitrogen were used to investigate feeding ecology in polyps from the Beaulieu River, UK (50° 80' 04.55″ N/1° 42' 28.12″ W) in both winter and summer conditions, and compared to laboratory-maintained polyps fed nauplii at 6 and 20 °C, respectively. In natural conditions, the isotopic composition of polyps indicated assimilation of nutrients derived from both benthic and pelagic food pathways, with seasonal switches between benthic-derived nutrients in winter and pelagic-derived nutrients in summer. In laboratory experiments, polyps assimilated food at 6 °C although metabolic processes were reduced, while at 20 °C, polyps starved as their increased metabolic costs could not be met from the food. Experiments on growth and asexual reproduction of -fed polyps of may not reflect natural metabolic rates especially at higher temperatures (e.g. 20 °C), because these polyps are not extracting sufficient resources from their food to fuel the increased metabolic costs associated with high temperatures.