An assessment of marine, estuarine, and riverine habitat vulnerability to climate change in the Northeast U.S.

Climate change is impacting the function and distribution of habitats used by marine, coastal, and diadromous species. These impacts often exacerbate the anthropogenic stressors that habitats face, particularly in the coastal environment. We conducted a climate vulnerability assessment of 52 marine, estuarine, and riverine habitats in the Northeast U.S. to develop an ecosystem-scale understanding of the impact of climate change on these habitats. The trait-based assessment considers the overall vulnerability of a habitat to climate change to be a function of two main components, sensitivity and exposure, and relies on a process of expert elicitation. The climate vulnerability ranks ranged from low to very high, with living habitats identified as the most vulnerable. Over half of the habitats examined in this study are expected to be impacted negatively by climate change, while four habitats are expected to have positive effects. Coastal habitats were also identified as highly vulnerable, in part due to the influence of non-climate anthropogenic stressors. The results of this assessment provide regional managers and scientists with a tool to inform habitat conservation, restoration, and research priorities, fisheries and protected species management, and coastal and ocean planning.

Vegetation survey of the Khomas Hochland in central-western Namibia: syntaxonomical descriptions

Background: The Great Escarpment of southern Africa takes the form of an extended mountainous highland in central-western Namibia, commonly referred to as the ‘Khomas Hochland’. It is regarded as an area of high botanical diversity. Yet only few localised studies on the vegetation composition are available. The Khomas Hochland is formed on the southern part of the Damara Orogen and dominated by metamorphosed sediments. Climatically it forms a transition between the hot desert of the Namib and the slightly cooler hot steppe in the inland.Objectives: To classify and provide syntaxonomical descriptions of the vegetation of the Khomas Hochland.Methods: A dataset comprising 1151 relevés and 914 species was compiled from various surveys, mostly collected under, and to the standards of, the umbrella project ‘Vegetation Survey of Namibia’. For first classifications, the data set was reduced to a synusial set consisting of trees, shrubs, dwarf shrubs and grasses only.Results: The classification resulted in four major landscape units, being the Pre-Namib and Escarpment zone, the Khomas Hochland proper, riverine habitats as well as surrounding lowlands. The classification was further refined using Cocktail procedures to produce 30 associations, one with four sub-associations. These are described in this paper.Conclusion: A classification of synoptic data grouped the associations into five orders and one undefined cluster of associations on specialised desert habitats. Four of these orders correspond to the habitat types identified in the first classification. The fifth order, the Senegalio hereroensis–Tarchonanthoetalia camphorathi, represents high mountains of the central Khomas Hochland, which link biogeographically to the grassland biome in South Africa.

Comparison of the Genetic Structure of Invasive Bigheaded Carp (Hypophthalmichthys spp.) Populations in Central-European Lacustrine and Riverine Habitats

Bigheaded carps (bighead carp, Hypophthalmichthys molitrix, and silver carp, Hypophthalmichthys nobilis) and their hybrids play an important ecological and economic role in their original habitat, while their introduced stocks may pose serious ecological risks. To address questions about the persistence and invasiveness of these fish, we need to better understand their population structures. The genetic structures of bigheaded carp populations inhabiting Lake Balaton and the Tisza River were examined with ten microsatellite markers and a mitochondrial DNA marker (COI). The Lake Balaton stock showed higher genetic diversity compared with the Tisza River stock. Based on hierarchical clustering, the Tisza population was characterized only by only silver carps, while the Balaton stock included hybrid and silver carp individuals. All COI haplotypes originated from the Yangtze River. Based on the high genomic and mitochondrial diversity, along with the significant deviation from H–W equilibrium and the lack of evidence of bottleneck effect, it can be assumed that bigheaded carps do not reproduce in Lake Balaton. The present stock in Balaton may have originated from repeated introductions and escapes from the surrounding fishponds. The Tisza stock consists solely of silver carp individuals. This stock appears to have significant reproductive potential and may become invasive if environmental factors change due to climate change.

South American freshwater fish diversity shaped by Andean uplift since the Late Cretaceous

South America is home to the highest freshwater fish biodiversity on Earth. The hotspot of species richness is located in the western Amazon Basin, and richness decreases downstream along the Amazon River towards the mouth at the Atlantic coast, which contradicts the positive relationship between stream size and biodiversity that is commonly observed in river systems across the world. We investigate the role of river rerouting events caused by Andean mountain building and repeated episodes of flooding in western Amazonia in shaping the modern-day richness pattern of freshwater fishes in South America. To this end, we combine a reconstruction of river networks following Andean surface uplift since 80 million years ago with a mechanistic biological model simulating dispersal, allopatric speciation and extinction over the dynamic landscape of rivers and lakes. We show that the numerous small river rerouting events in western Amazonia resulting from mountain building produced highly dynamic riverine habitats that caused high diversification rates, shaping the exceptional present-day richness of this region. The history of marine incursions and lakes, including the Miocene Pebas megawetland system in western Amazonia, played a secondary role. This study is a major step towards the understanding of the processes involved in the interactions between the solid Earth, landscapes, and life of extraordinary biodiverse South America.

Ecology and Genetics of Cyperus fuscus in Central Europe—A Model for Ephemeral Wetland Plant Research and Conservation

The ecology and species diversity of ephemeral wetland vegetation have been fairly well studied, but the biology of its characteristic species has rarely been investigated holistically. Here we combine previous results on the genetic diversity of a suitable model species (the diploid Cyperus fuscus) with new data on its historical and recent occurrence, its ecological and climatic niche, and the associated vegetation. Analysis of phytosociological relevés from Central Europe revealed a broad ecological niche of C. fuscus with an optimum in the Isoëto-Nanojuncetea class, extending to several other vegetation types. Overall species composition in the relevés highlight C. fuscus as a potential indicator of habitat conditions suitable for a range of other threatened taxa. Analysis of historical records of C. fuscus from the Czech Republic showed an increasing trend in the number of localities since the 1990s. It seems that recent climate warming allows the thermophilous C. fuscus to expand its range into colder regions. Isoëto-Nanojuncetea and Bidentetea species are well represented in the soil seed bank in both riverine and anthropogenic habitats of C. fuscus. Vegetation diversity has a weak negative effect and anthropogenic (compared to riverine) habitats have a strong negative effect on genetic diversity in this species.

The Species Diversity of Tropical Freshwater Rotifers (Rotifera: Monogononta) in Relation to Environmental Factors

This study aims to evaluate the diversity of rotifers in various freshwater habitats in Da Nang City, Vietnam, and to investigate the relationship between community structure and environmental conditions. A total of 75 rotifer species belonging to 25 genera and 17 families were recorded, out of which seven species are new to Vietnam. Species from the families Brachionidae and Lecanidae are abundant (containing about 50% and 69.44%, respectively) in the total rotifer species in both lacustrine and riverine habitats. The number of rotifers recorded in the lakes (64 taxa) was much higher than those in rivers (36 taxa), and this is possibly due to the conditions in lakes being more favorable for the development of small zooplanktons. The significant influences of environmental factors (temperature, pH, turbidity, and trophic state) on the rotifer community were well-reflected in the distribution of commonly found species in lakes (p-value < 0.05). Our study results enrich the data on the diversity and the ecology of rotifers in Vietnam.

Does river channelization increase the abundance of invasive crayfish? Survey of Faxonius limosus in small Central European streams

The aim of this study was to assess whether regulated river reaches show higher numbers of the spiny cheek crayfish Faxonius limosus, a common freshwater invader in Europe. Man-made alterations of riverine habitats may increase their susceptibility to biological invasions. This phenomenon is commonly studied in the context of dam reservoirs; however, the impact of river channelization and the resulting riverine habitat homogenization on the success of invasive species are mostly lacking. Surveys were conducted in natural and channelised river stretches in five rivers of south-central Poland. General linear mixed model analysis showed that crayfish abundance is usually higher at sites located within regulated reaches. The likely reason for the detected differences in abundance of crayfish may be related to decreased food-web complexity and lack of predators in a homogenised habitat. The results suggest that the channelization of small watercourses may increase the abundance of invasive species F. limosus and its pressure on native European crayfish. However, due to limited data obtained in field, our study should be considered as a pilot one.

Tiger beetles (Coleoptera, Cicindelidae) of Northern Mindanao region (Philippines): checklist, distributional maps, and habitats

The knowledge about tiger beetle fauna of the Northern Mindanao region (Philippines) is summarized based on literature data and new records. Thirty species classified in ten genera (Tricondyla, Neocollyris, Protocollyris, Therates, Prothyma, Heptodonta, Thopeutica, Lophyra, Calomera, and Cylindera) were documented from the area (56% of tiger beetle fauna of Mindanao and 21% of Philippine species). Twelve species were noted from Northern Mindanao region for the first time, including five taxa, Neocollyris speciosa, Calomera angulata, Cylindera minuta, Lophyra striolata tenuiscripta, and Thopeutica virginea, not recorded from Mindanao before. Distribution maps for all recorded species and the first photographs of habitats for some species in Mindanao and/or in the Philippines are provided. Eight species (27% of recorded fauna) were noted from riverine habitats while 18 tiger beetles (60%) were typical forest taxa; in the case of four species, their habitats in Northern Mindanao region are not known.

Identifying priority areas for research and conservation of the largetooth sawfish Pristis pristis in Colombia and Panama

Sawfishes are considered one of the most endangered families of fishes in the world. Their diadromous ecology and vulnerability to fishing nets have brought most populations to the brink of collapse. Conservation of the surviving populations is hindered by the paucity of historic and contemporary catch and observational records, and assessments of suitable coastal and riverine habitats. Colombia and Panama are two of 14 countries considered as a high priority for the development of species-specific national legal protection of the critically endangered largetooth sawfish (Pristis pristis). To construct a baseline for the temporal and spatial distribution of the largetooth sawfish in Colombia and Panama, we collected historical records from museum databases and from literature over the past century, analysed available small-scale fisheries landings databases, and conducted interviews with fish workers in 38 locations across both countries. We found 257 records of sawfish occurrences across both countries between 1896 and 2015, with 69% of the records before the year 2000. The declining trend in the frequency of observations was corroborated by fishers, who reported fewer sawfish catches over the last 20 years. Using kernel density estimation of recent encounter locations, we identify potential hotspots that may represent extant populations of sawfish. These locations are broadly characterized by their remoteness and high mangrove forest cover. Given the length and cultural diversity of the Pacific coastlines of Colombia and Panama, and the inaccessibility of many of the communities, our findings provide important guidance to target rapid conservation and fisheries interventions to priority areas. We suggest that the relative success of community-managed fishing areas in the region makes this a valuable platform on which to build local stewardship of marine resources, while raising awareness of the need to safeguard critically endangered largetooth sawfish.