Hydrobiologia

Cheng, Ruli; Luo, Yang; Li, Qinghua; Zhang, Yufeng; Liu, Zhihao; Chen, Qiliang; Li, Yingwen; Shen, Yanjun

doi: 10.1007/s10750-023-05297-1pmid: N/A

The fish communities in the Yangtze River (YR) basin is in a degraded state due to the influence of human factors. Here, we used environmental DNA (eDNA) metabarcoding technology to conduct a survey on the fish diversity in the upper reaches of the YR from Jiangjin to Fuling to search for better monitoring methods. We set up 12 sampling sites in this river section, collected 36 environmental samples, and obtained 5,067,423 valid sequences. After conducting an annotated comparative analysis utilizing the NCBI public database, a total of 104 freshwater fish species were identified, belonging to 8 orders, 24 families, and 72 genera. This included six nationally protected fish species, as well as endemic, introduced, and previously unrecorded species within this basin. The results of this survey indicate a trend toward miniaturization of species and a decline in endemic fish species as well as an increase in exotic fish species in the region, which implied the fish communities in the upper YR region remains in a degraded state. However, the species composition at the family level has remained relatively stable over the past decade. Furthermore, the diversity analysis revealed that fish composition and diversity exhibit variability across different locations.

Jaszczyńska, Aleksandra; Falniowski, Andrzej; Prevorčnik, Simona; Osikowski, Artur; Hofman, Sebastian

doi: 10.1007/s10750-022-05106-1pmid: N/A

The Western Balkans hosts the richest subterranean aquatic gastropod fauna in the world. The main factors shaping intraspecies diversity are thought to be isolation and endemism. In the genus Belgrandiella, minute snails inhabiting subterranean waters and springs in Central Europe and Balkans, molecular studies have shown much fewer valid species than previously anticipated. The present study applies mitochondrial cytochrome c oxidase subunit I, histone 3, and RAPD analysis, to check the inter- and intraspecies genetic diversity in 36 Belgrandiella populations from caves, springs and interstitial aquifers. The level of gene flow is assessed to check if these snails form a widespread genetically uniform metapopulation or rather follow the highly endemic pattern. The studied populations have been assigned to six species. In the most widely distributed B. kusceri from 21 populations, 60 sequenced specimens represent 16 haplotypes. While the same haplotypes are present in distant populations, gene flow between the other populations is low. Nei distances for RAPD show no geographic pattern. The interspecies differences in COI evidently confirm the time of speciation in Pleistocene, before karstification, which rejects speciation within isolated caves. The pattern observed in Belgrandiella seems more similar to the one described in Montenegrospeum than in Kerkia.

Martaeng, Rasmus; Obst, Matthias; Kuklinski, Piotr

doi: 10.1007/s10750-023-05184-9pmid: N/A

This is a phylogeographical study of Juxtacribrilina mutabilis, a recently described bryozoan from Japan with sightings in Sweden, Norway, and Maine (US), to test how fast and far it has expanded across Europe in recent years. J. mutabilis settles easily on ship hulls, making it a useful model organism for studying long-distance invasion pathways. The study was conducted using Autonomous Reef Monitoring Structures (ARMS) to monitor the entire European coastline and Svalbard for J. mutabilis using DNA metabarcoding. During the time between its first sighting in Europe 2008 and the last ARMS retrieval 2020, the data shows how J. mutabilis has gained a pan-European distribution, being genetically identified in 14 new distinct locations. Presence/absence of barcodes were confirmed by image-based identification in 74% of the samples. Fourteen haplotypes never reported before were discovered in a 264 bp region of the cytochrome oxidase I gene. Two haplotypes (HP1 and HP3) occurred frequently and geographically widely dispersed, indicating intercontinental connectivity. Two locations, Koster and Getxo showed particularly high genetic diversity with similar haplotype networks suggesting continuous gene flow across oceanographically unlinked regions. Given the recent description of J. mutabilis and the relatively few historical encounters, the genetic diversity described here suggests an unusually fast range expansion within the last two decades. Such global spreading events of fouling organisms may become more common in the future as a result of more frequent and interconnected ship traffic.

Loyn, Richard H.; Rogers, Danny I.; Swindley, Robert J.; Menkhorst, Peter W.; Stamation, Kasey; Haynes, Suelin; Graham, Heather; Hepworth, Graham; Steele, William K.

doi: 10.1007/s10750-023-05265-9pmid: N/A

Nutrients such as nitrogen and phosphorus are typically considered detrimental to wetland values, but waterfowl can be numerous on nutrient-rich wetlands. Waterfowl were counted three to six times per year on nine treatment lagoons and associated wetlands (2,025 ha) at the Western Treatment Plant (south-east Australia) from 2000, to help maintain ecological values of this Ramsar-listed wetland as well as treating sewage for a large city (Melbourne). Up to 185,000 waterfowl were counted, varying with season, continental rainfall and lagoon operation. Nutrient levels were reduced on Lake Borrie lagoon in 2005 (as part of an Environmental Improvement Program) and restored in 2015. Waterfowl declined on Lake Borrie lagoon from 2005 when it received treated effluent not raw sewage, and increased in 2015 when it received partially treated sewage. This pattern was highly significant for total waterfowl and most species and guilds at Lake Borrie but was not replicated on other lagoons. Modelling revealed positive relationships between waterfowl numbers and nutrient concentrations, including ammonia and nitrite, to moderate levels. This shows that with careful management nutrient enrichment can have positive benefits, allowing artificial wetlands such as wastewater treatment plants to support high densities of waterbirds and the food webs that sustain them.

Jaureguizar, Andrés J.; De Wysiecki, Agustín M.; Cortés, Federico; Milessi, Andrés C.

doi: 10.1007/s10750-023-05293-5pmid: N/A

The nursery habitats of the broadnose sevengill shark Notorynchus cepedianus (Péron, 1807) remain largely unknown. The identification of these critical habitats is important for the conservation of these top-down regulator species and general coastal ecosystem dynamics. We investigated the role of the San Antonio cape (Argentina) as a nursery habitat for N. cepedianus and tested the hypothesis that physical conditions (turbidity, sea surface temperature) are more important than prey abundance in the habitat use by young-of-the-year (YOY). We used the presence, relative abundance, and size structure of YOY from a small-scale gillnet fishery (2008–2014) to assess the intra- and inter-annual persistence in habitat use. The results indicated intra- and inter-annual persistence in estuarine habitat use, and comparisons with previous studies suggested that YOYs were more commonly encountered in San Antonio cape than in other suitable areas. Finally, the YOYs’ use of the area may be explained by a combination of the spatial–temporal variation in turbidity conditions and food abundance. These results suggested San Antonio cape as a nursery habitat for N. cepedianus YOYs and highlighted the importance of understanding key biophysical effects that regulate the use, movement, and residency of N. cepedianus in their nursery habitats.

Pan, Ling; Zhu, Han; Xi, Yi-Long; Cheng, Xin-Feng; Ge, Ya-Li; Xiang, Xian-Ling; Wen, Xin-Li

doi: 10.1007/s10750-023-05288-2pmid: N/A

To test the hypothesis that non-consumptive predation pressures favor genotypes that have higher equilibrium densities or mictic ratios, we expose replicate populations of the rotifer Brachionus angularis to low (LK) and high (HK) concentrations of predator Asplanchna kairomones. Over 75 days (25 asexual generations) of selection, LK-treated populations have higher equilibrium densities and lower mictic ratios than the control populations. The opposite occurs for HK-treated populations. These results suggest that compared with the control, LK and HK select for genotypes with higher equilibrium densities and mictic ratios, respectively. Common garden bioassays reveal that in the absence of Asplanchna kairomones, populations with an LK selection history have a higher average intrinsic rate of population increase, and those with an HK selection history have a higher average mictic ratio than those with the control selection history, which suggest that adaptations to LK and HK increase average intrinsic rate of population increase and mictic ratio of prey populations, respectively. Increased intrinsic rate of population increase and mictic ratio can serve as strategies of offsetting mortality from predation and escaping the predator, and thus enable prey to survive low and high predation pressures, respectively.

Raymond, Scott; Todd, Charles; Ryall, Jordi; Fanson, Ben; Koehn, John; Tonkin, Zeb; Hackett, Graeme; O’Mahony, Justin; Berry, Kelvin; Lieschke, Jason; Rourke, Meaghan; Ward, Keith

doi: 10.1007/s10750-023-05289-1

Nguyen-Ngoc, Lam; Weber, Sarah C.; Doan-Nhu, Hai; Subramaniam, Ajit; Voss, Maren; Montoya, Joseph P.

doi: 10.1007/s10750-023-05290-8pmid: N/A

The South China Sea (SCS) is a hydrographically complex and physically dynamic marginal sea of great economic importance. Primary production in the SCS experiences strong seasonal forcing through the monsoon cycle, which affects both riverine runoff and circulation within the basin. The summer monsoon in particular produces a mix of waters affected by the Mekong outflow and coastal upwelling embedded within a dynamic wind-driven surface circulation. Here, we discuss the distribution, abundance, and symbiotic state of a suite of host diatoms and Diatom-Diazotroph Associations (DDAs) in different habitats defined in terms of the physical and biological characteristics of the SCS during the early stages of the SW Monsoon of 2016. DDA host diatoms were broadly distributed throughout our study region, and we found intact symbioses in all of the habitats sampled, though infection rates (abundance of hosts bearing symbionts) and infection intensities (number of symbionts per host) were lowest in waters affected by coastal upwelling. Host infection rates tended to be highest in offshore waters, and DDA host diatoms generally varied widely in size and infection intensity both within and among defined habitats. These differences may reflect different optimal strategies for allocating biomass and energy between host and symbiont.

Messetta, María Laura; García, Patricia Elizabeth; Hegoburu, Cecilia; Giordano, Andres; Butturini, Andrea; Feijoó, Claudia

doi: 10.1007/s10750-023-05292-6pmid: N/A

Our study aimed to analyze the effects of land use coverage (agricultural, cattle breeding, natural vegetation, and others) on the concentration and chemical characteristics of DOM in Pampean streams. We selected 41 streams situated in the Buenos Aires Province, Argentina in autumn, spring, and summer. In each stream, we determined DOC concentration and adopted a spectroscopic approach to characterize DOM optical qualitative properties. Agricultural land use coverage was predominant in all the sampled streams. Our results showed that DOC ranged from ~ 3 to 26 mg L−1, higher DOC concentrations were found in streams from Salado River and its tributaries. The variation in DOM properties was related to land use coverage and season. According to that, we found similar DOM optical properties during summer due to extremely high precipitation during the sampling period, suggesting higher hydrological connectivity between catchments and streams. The Pampean region is undergoing an agricultural intensification that affects the riparian zone of streams. This is the first study, which assesses the changes in DOM optical features concerning land use coverage in streams located in the Pampean region.

Dias, Ester; Dromby, Morgane; Ferreira, Rita; Gil, Ágatha; Tejerina, Raquel; Castro, L. Filipe C.; Rosso, Massimiliano; Sousa-Pinto, Isabel; Hoffman, Joel C.; Teodósio, Maria A.; Dinis, Ana; Alves, Filipe

doi: 10.1007/s10750-023-05294-4pmid: N/A

The common bottlenose dolphin (Tursiops truncatus) is a top marine predator widely dispersed in coastal and pelagic habitats and with a generalist feeding behavior. Yet, information on the trophic ecology of animals inhabiting pelagic environments is still scarce. Using carbon (δ13C: 13C/12C) and nitrogen (δ15N: 15N/14N) stable isotope ratios, we identified and quantified the main groups of prey assimilated by bottlenose dolphins inhabiting an oceanic habitat (Madeira Island, East Atlantic). Bottlenose dolphins assimilated pelagic, schooling fish (such as blue jack mackerel, Trachurus picturatus) and mesopelagic and demersal squids, which reinforces the pelagic dietary composition of insular/oceanic dolphins. Also, intra-seasonal differences were found in their stable isotope ratios, which suggest intraspecific variability in the feeding behavior among individuals living in the same area. Sex was not the main factor contributing to these differences, suggesting the lack of trophic niche segregation between adult males and females in this offshore environment. Nonetheless, further studies including different life stages and information on the ecophysiological requirements are necessary to disclose the factors responsible for the observed variability. This study showed that insular dolphins fed primarily on economically important pelagic prey, highlighting the need of developing management strategies that integrate conservation in fisheries plans.