Small Coastal Rivers Research Articles

Land-Use/Cover Change and Driving Forces in the Pan-Pearl River Basin during the Period 1985–2020

Land use/cover change (LUCC) is a vital aspect representing global change and humans’ impact on Earth’s surface. This study utilized the ESRI Land Cover 2020 and China Land Cover Dataset (CLCD), along with historical imagery from Google Earth, to develop a method for the assessment of land use data quality. Based on the assessment, the CLCD was updated to generate an improved Re-CLCD for the Pan-Pearl River Basin (PPRB) from 1985 to 2020, and to analyze LUCC in the PPRB over the past 35 years. The results indicate the following: (1) Among the seven land uses, built-up land experienced the most dramatic change, followed by cropland, forestland, grassland, shrubland, waterbody, and bare land, with notable increases in built-up land and forestland, and rapid decreases in cropland, grassland, and shrubland. (2) The magnitude of land use changed very widely, with the highest change in the Pearl River Delta, followed by small coastal river basins in southern Guangdong and western Guangxi, the Dongjiang River Basin, the Hanjiang River Basin, the Xijiang River Basin, the Beijiang River Basin, and lastly, Hainan Island. (3) The largest increase happened in built-up land, with a total increase of 12,184 km2, mainly due to the occupation of cropland and forestland, corresponding to the highest decrease in cropland, with a net loss of 10,435 km2, which was primarily converted to forestland and built-up land. The study results are valuable in providing a scientific basis for policy overhaul regarding land resources and management to safeguard ecological balance and promote sustainable development in the Pan-Pearl River Basin.

Observations of river-wave interactions at a small-scale river mouth

Small coastal rivers often discharge directly into the surfzone, where the fate of freshwater and river-borne materials (e.g., sediment, nutrients and contaminants) is primarily determined by interactions between buoyant plume processes and the nearshore wave forcing. Understanding river-wave interactions in the surfzone is essential to assess coastal water quality and impacts on ecosystem health along adjacent shorelines. These interactions are modulated by the variability in river discharge, offshore wave climate, tidal forcing, and surfzone dynamics, and therefore occur over a wide range of timescales. However, the different timescales at which river-wave interactions occur have not been fully investigated. Here we use in-situ and remote (drone-based) observations collected at the mouth of the Maipo River, a small-scale river system in central Chile, to investigate interactions between the river outflow and the incident wave forcing that may influence the distribution of freshwater along the coast. We focus on interactions occurring at infragravity (wave groups), tidal, and synoptic (offshore wave climate) timescales. The observations included inlet and surfzone deployments, and documented low river discharge conditions (QR∼ 20–27 m3s−1) with variable wave forcing (Hs∼ 1–3 m). We observed that the salinity signal at the river mouth is strongly modulated by the tide, with a freshwater plume forming solely during the ebb. Large oscillations associated to infragravity (IG) motions are continuously observed on top of the tidal variability. These oscillations are evidenced in surfzone salinity, inlet water levels, and inlet velocity during the early ebb when the freshwater plume starts to develop. As the plume evolves into a strong outflow jet during the late ebb, they are not observed in the inlet and become restricted to the surfzone. The combined analysis of drone imagery and in-situ observations suggests that the observed variability in surfzone salinity at IG frequencies is associated with the arrival of wave groups and the propagation of wave fronts in the plume area. In particular, during the late ebb, the large oscillations in surfzone salinity (amplitude of 15–20 psu) are explained by a contraction and expansion of the outflow plume in response to the variability in the onshore wave forcing at the timescale of wave groups. On synoptic timescales (hours to days), the surfzone salinity responded to the intensity of the offshore wave forcing (∼ 20 m depth), with higher waves promoting lower salinity as freshwater is mostly retained near the coast. A wave-river momentum comparison confirms that the wave forcing had the potential to trap freshwater in the surfzone. This study shows that nearshore waves may influence the dynamics of small river plumes and the fate of freshwater (and associated terrestrial materials) on a wide range of timescales, from infragravity (1–5 min) to hours and days.

Effects of large dams on the aquatic food web along a coastal stream with high sediment loads

The contribution of two basal energy sources – detrital organic matter and primary producers – as part of aquatic food webs varies typically along river continua. A host of barriers to river flow increase the water residence time and sediment and nutrient retention in reservoirs worldwide, and potentially alter the balance between detritus-based and algae-based energy pathways in the downstream food webs. We explored this issue on the Sélune River (Normandy, France), a small coastal stream that drains an agricultural catchment with high sediment runoff. Seasonal measurements of the following parameters were compared upstream and downstream of the reservoirs of two large dams (16 m and 36 m high): sediment fluxes, nutrient and chlorophyll a concentrations, algal communities in the epilithic biofilm (taxonomic composition, biomass and growth), and benthic invertebrate communities (abundance and trophic guild structure). As anticipated, annual sediment fluxes were much lower downstream of the reservoirs, where significant decreases in water turbidity, phosphate and silicate concentrations were recorded. A higher chlorophyll a concentration in water and a higher contribution of pelagic algae taxa to the photosynthetic biofilm suggested drifting and deposition of reservoir-borne phytoplankton downriver. Photosynthetic biofilm growth was higher downstream of the reservoirs in spring and fall, and so was the abundance of herbivores in the invertebrate community, notably scrapers and algae eaters. Energy pathways within riverine food webs were traced using stable isotope analyses of carbon (C) and nitrogen in the tissues of aquatic consumers (invertebrates and fish). Mixing models revealed a discontinuity in the origin of the C entering the food webs along the river continuum, confirming a greater contribution of algal C to aquatic consumers downstream of the reservoirs. These results illustrate mechanisms whereby large reservoirs can modulate C flow in food webs along a small coastal river with high sediment loads, and make it possible to anticipate the effects of dam removal on the future river ecosystem.

Really a "secondary gill under the skin"? Unveiling "dorsal vessels" in freshwater slugs (Mollusca, Panpulmonata, Acochlidimorpha).

The freshwater slugs of the genus Acochlidium (Heterobranchia, Gastropoda, and Acochlidimorpha) are peculiar, one to two centimeter sized animals found only in small coastal rivers and streams of Southeast Asian and Western Pacific islands. When first described by Bücking, the author observed a branching "net of dendritic vessels connected to the heart," which he assumed to have replaced the original gastropod gill. In the present study, we compare the renopericardial systems of four Acochlidium species in microanatomical, histological and ultrastructural detail and identify where exactly the enigmatic, subepidermal "dorsal vessels" connect to the renopericardial system to examine if they can really function as a gill. Acochlidium have elaborate renopericardial systems compared to their ancestrally marine and also freshwater relatives. The primary site of ultrafiltration is the epicardium of the atrium with podocytes as usual for gastropods. The "dorsal vessels" in Acochlidium are extensions of the outer epithelium of the pericardial cavity and represent true vessels, that is, coelomatic channels, having an endothelium with podocytes. Hence, they considerably enlarge the site of ultrafiltration increasing the pericardial surface. "Dorsal vessels" in Acochlidium are therefore not homologous to externally similar morphological structures in Sacoglossa (marine panpulmonate slugs and snails). The multiplication of renopericardioducts in Acochlidium is a unique feature within Mollusca that enhances the negative pressure necessary for ultrafiltration in the thin, tube-like dorsal vessels and as a consequence the transport of primary urine from the pericardium to the kidney. The circulatory and excretory systems in Acochlidium are adaptations to a lifestyle in their freshwater environment in which snail bodies are hyposmotic and accrue considerable influx of surplus water into the body, which needs to be expelled.

Ichthyodiversity of a small coastal river in Bangladesh

Small rivers are often ignored in terms of conservation actions and biodiversity management in Bangladesh. Despite having significant ecological and economic importance of these rivers, there is limited study done so far. To partially fulfill this gap, this study aimed to assess the fish and shellfish biodiversity of a small coastal river named Tiakhali from southern Bangladesh. A total of 26 finfish and 7 shellfish species were identified where 50% of finfish and all of the shellfish species were from the order Perciformes and Decapoda, respectively. Results showed that 76.9% of finfish and all of the shellfish species were categorized into the least concern category based on IUCN Red List. Estimated Shannon’s, Margalef’s, Buzas & Gibson’s and Simpson’s indices were 1.189, 2.649, 0.435 and 0.435 for fish and 1.662, 0.758, 0.224 and 0.224 for shellfish, respectively. This study showed that Tiakhali river’s fish biodiversity was comparatively smaller than big rivers. The findings of this study might serve as a baseline for future works and will help policymakers to pay attention to conserve such small rivers and their biodiversity in future. Dhaka Univ. J. Biol. Sci. 32(1): 1- 10, 2023 (January)

Social and environmental indicators of the Jaboatão river water basin associated with diseases related to inadequate environmental sanitation (DRIES)

Located in the Southern Mata region of the state of Pernambuco, the Jaboatão River Hydrographic Basin (JRB) has an area of 442 km². Part of the group of small coastal rivers (GL2), the JRB drains the municipalities of Recife, Jaboatão dos Guararapes, Moreno, São Lourenço da Mata, Cabo de Santo Agostinho, and Vitória de Santo Antão. In addition to contributing to the public supply of the Metropolitan Region of Recife, the JRB receives domestic, industrial and agro-industrial effluents along its route. The JRB runs through densely occupied municipalities with irregular land use and deficiencies in infrastructure, reflecting social, economic and environmental problems. The objective of this study is to make a diagnosis of the socio-environmental indicators in the JRB and correlate them with the main waterborne diseases related to the lack of basic sanitation. The study involved a literature review and a survey of secondary data. Regarding the water quality of the JRB, it was found to vary between Polluted and Very Polluted during the monitored period. With regard to environmental impacts, deforestation, waste dumping and irregular occupation of riverbanks were observed, causing problems for the fauna, flora and the population. In relation to the basic sanitation indicator in the municipality of Jaboatão dos Guararapes, among the obstacles raised was the fact that the municipality does not have a Municipal Policy on Basic Sanitation and the Jaboatão dos Guararapes Municipal Administration does not have a Municipal Basic Sanitation Plan; There is a scarcity of systematized information that supports the process of measuring environmental health; between urban and rural areas there are disparities in access to sanitation services, requiring the adoption of public policies to expand sanitation services in order to assist these populations and thus promote the universalization of sanitation access. The deficiency in basic sanitation in the municipality of Jaboatão dos Guararapes hinders local sustainable development, causing social, economic and environmental impacts. Regarding the number of hospital admissions caused by diseases related to inadequate environmental sanitation (DRIES) in the municipalities that are part of the JRB, Recife stood out with 13,191 hospitalizations in the study period, and in 2010 had the highest number of hospitalizations (2,204). With regard to the number of deaths caused by DRIES, Recife also stood out with 4,208 deaths during the study period.

Watershed Classification Predicts Streamflow Regime and Organic Carbon Dynamics in the Northeast Pacific Coastal Temperate Rainforest

AbstractWatershed classification has long been a key tool in the hydrological sciences, but few studies have been extended to biogeochemistry. We developed a combined hydro‐biogeochemical classification for watersheds draining to the coastal margin of the Northeast Pacific coastal temperate rainforest (1,443,062 km2), including 2,695 small coastal rivers (SCR) and 10 large continental watersheds. We used cluster analysis to group SCR watersheds into 12 types, based on watershed properties. The most important variables for distinguishing SCR watershed types were evapotranspiration, slope, snowfall, and total precipitation. We used both streamflow and dissolved organic carbon (DOC) measurements from rivers (n = 104 and 90 watersheds respectively) to validate the classification. Watershed types corresponded with broad differences in streamflow regime, mean annual runoff, DOC seasonality, and mean DOC concentration. These links between watershed type and river conditions enabled the first region‐wide empirical characterization of river hydro‐biogeochemistry at the land‐sea margin, spanning extensive ungauged and unsampled areas. We found very high annual runoff (mean > 3,000 mm, n = 10) in three watershed types totaling 59,024 km2 and ranging from heavily glacierized mountain watersheds with high flow in summer to a rain‐fed mountain watershed type with high flow in fall‐winter. DOC hotspots (mean > 4 mg L−1, n = 14) were found in three other watershed types (48,557 km2) with perhumid rainforest climates and less‐mountainous topography. We described four patterns of DOC seasonality linked to watershed hydrology, with fall‐flushing being widespread. Hydro‐biogeochemical watershed classification may be useful for other complex regions with sparse observation networks.

Demographics and exploitation of two Near Threatened freshwater eels, Anguilla bengalensis and Anguilla bicolor, in small‐scale subsistence fisheries and implications for conservation

Abstract Tropical freshwater eels (Anguilla bengalensis and Anguilla bicolor) contribute a major share of the world's wild‐caught eel production, having become the next major target owing to the declines in availability of both Anguilla japonica and Anguilla anguilla, species that have traditionally contributed to eel aquaculture and trade. Although both A. bengalensis and A. bicolor are assessed as Near Threatened on the International Union for Conservation of Nature Red List, these assessments are primarily based on anecdotal information and local knowledge on population declines. Demographics and exploitation levels of A. bengalensis and A. bicolor were determined from small coastal river systems, and their adjoining aquascapes in the Western Ghats hotspot of southern peninsular India, and the value of these data for future conservation planning discussed. The computed estimates of annual catch data for freshwater eels from the study region are between 0.17 (A. bicolor) to 0.30 t (A. bengalensis). Virtual population analysis of exploitation showed a drastic decline (in number) in the length groups >45 cm for both species, suggesting that they were less likely to attain their asymptotic length in the region. Current exploitation rates of A. bengalensis are unsustainable, and those for A. bicolor are almost close to reaching this level. Exploitation of all life stages from yellow eels to adults (29–171 cm) is likely to cause recruitment failure and significant mortality of spawning individuals of both species. An integrative conservation approach, including raising awareness (leading to voluntary restrictions), fishing closures in reservoirs, village‐level quotas, and regular monitoring of populations, will ensure a sustainable future for the freshwater eel species in the Western Ghats hotspot, and elsewhere in the tropics where these species are exploited.

Distribution and Risks of Microplastics in Sediments of a Small Coastal River–Estuary System: Functional Areas, Wastewater Treatment Plants, and Dams

Distribution and Risks of Microplastics in Sediments of a Small Coastal River–Estuary System: Functional Areas, Wastewater Treatment Plants, and Dams

Bedload transport and dune bedforms characteristics in sand-bed rivers supplying a retreating beach of the northern Adriatic Sea (Italy)

Study RegionThe coast of the Emilia-Romagna Region in northern Italy consists of about 210 km of sandy beaches that have been attracting tourists for decades. Since the 1980s, erosion processes resulted in a remarkable beach retreat, notwithstanding the construction of several protections works. Study FocusIn 2005–2006 and 2017–2020, 30 floods of two small rivers feeding the beaches of Ravenna, Fiumi Uniti and Savio, were monitored and bedload was measured with a Helly-Smith sampler. Riverbed bathymetric surveys were carried out after some selected floods to investigate the occurrence and geometry of alluvial bedforms.The dune migration method was also used to calculate bedload. Results provided by this method are very encouraging. New Hydrological insights for the RegionTo the authors knowledge, this field investigation on the bedload transport of small coastal rivers is the first one of this kind in the Adriatic and provides the regional land managers with a useful tool to predict the bedload yield for future scientifically based interventions, and hopefully successful, beach protection works.The bedload data indicate a higher variability of bedload for discharges lower than bankfull flow, whereas a stronger control of discharge is evident for larger floods. Though the bedload of the study rivers proved to be higher than in the largest river of the Region, it resulted rather low and witnesses sediment supply-limited conditions.

Occurrence, distribution, and ecological risk assessment of emerging and legacy contaminants in the Kadicha river in Lebanon.

The Kadicha river basin in Northern Lebanon is an illustrative example of multiple pressures encountered in the Mediterranean region: it is a small coastal river affected by rapid urbanization, population growth (drastically impacted by the influx of Syrian refugees), and a chronic default of wastewater treatment. In this context, multiple classes of contaminants may attain the river accumulating in sediment. However, very little information is available in the literature on the contamination status in such stressed Mediterranean contexts. This study proposed a first contamination evaluation of a small Mediterranean river submitted to multiple pressures. Two sediment sampling campaigns along sites impacted by increasing urban gradient within the Kadicha river basin were performed to determine the occurrence and the environmental risks of both emerging and legacy contaminants. The results revealed the detection of the 41 studied compounds. The highest concentrations were attained by PAHs and polycyclic musks (up to 311.79, 94.22, and 81.13 ng/g of dry weight for PAH, cashmeran, and galaxolide, respectively). The discontinuous urbanized upstream area and the estuary were the most contaminated areas of the river. An environmental risk assessment showed a hazard quotient (HQ) higher than 1 for both legacy and emerging compounds (EHMC and 4-MBC), indicating a potential risk to benthic species. Monitoring campaigns and implementation of wastewater treatment plants should be encouraged as the anthropogenic pressure on small Mediterranean rivers will increase over the years.

City planning and floods: The strategy of Montpellier

AbstractLocated between Marseille and Barcelona, Montpellier is one of the most attractive cities of the Mediterranean coast. It has more than 460,000 inhabitants and grows by 7,500 more inhabitants every year. This is largely due to its positive image and its freshly constructed neighbourhoods “Antigone” and “Port‐Marianne.” From the late 1970s, the municipality’s strategy was to organise the urban sprawl to the east and then towards the sea in the south of the city. The Lez, a small coastal river, well known for its spectacular flash floods, was the spine of this new urban growth. Internationally renowned architects and planners have been recruited to build these new “green” neighbourhoods (in French “éco‐quartiers”) located on lands that used to be flooded regularly. This urban policy is largely due to the Montpellier’s former mayor Georges Frêche and his deputy, the geographer Raymond Dugrand. The “urban planning” concept, or “urban design” projects, have largely been used by the local experts and officials to describe this development, but seem to be misused in this case. It has being mostly a political city‐project, still having the same objective as more than 30 years ago: to turn Montpellier towards the seaside. This paper will return to the strategy used at that time and, in retrospect, all the interrogations that have followed in terms of sustainable development and flood risk management.

Performance of automated methods for flash flood inundation mapping: a comparison of a digital terrain model (DTM) filling and two hydrodynamic methods

Abstract. Flash floods observed in headwater catchments often cause catastrophic material and human damage worldwide. Considering the large number of small watercourses possibly affected, the use of automated methods for flood inundation mapping at a regional scale can be of great help for the identification of threatened areas and the prediction of potential impacts of these floods. An application of three mapping methods of increasing level of complexity is presented herein, including a digital terrain model (DTM) filling approach (height above nearest drainage/Manning–Strickler or HAND/MS) and two hydrodynamic methods (caRtino 1D and Floodos 2D). These methods are used to estimate the flooded areas of three major flash floods observed during the last 10 years in southeastern France, i.e., the 15 June 2010 flooding of the Argens river and its tributaries (585 km of river reaches), the 3 October 2015 flooding of small coastal rivers of the French Riviera (131 km of river reaches) and the 15 October 2018 flooding of the Aude river and its tributaries (561 km of river reaches). The common features of the three mapping approaches are their high level of automation, their application based on a high-resolution (5 m) DTM, and their reasonable computation times. Hydraulic simulations are run in steady-state regime, based on peak discharges estimated using a rainfall–runoff model preliminarily adjusted for each event. The simulation results are compared with the reported flood extent maps and the high water level marks. A clear grading of the tested methods is revealed, illustrating some limits of the HAND/MS approach and an overall better performance of hydraulic models which solve the shallow water equations. With these methods, a good retrieval of the inundated areas is illustrated by critical success index (CSI) median values close to 80 %, and the errors on water levels remain mostly below 80 cm for the 2D Floodos approach. The most important remaining errors are related to limits of the DTM, such as the lack of bathymetric information, uncertainties on embankment elevation, and possible bridge blockages not accounted for in the models.

Cross-species gene enrichment revealed a single population of Hilsa shad (Tenualosa ilisha) with low genetic variation in Bangladesh waters

Tenualosa ilisha is a popular anadromous and significant trans-boundary fish. For sustainable management and conservation of this fish, drawing an appropriate picture reflecting population status of this species is very essential based on their all-strategic habitats in Bangladesh. In this study, 139 samples from 18 sites were collected and cross-species gene enrichment method was applied. Like most of the Clupeiforms, nucleotide diversity of this shad was very low (0.001245–0.006612). Population differences between most of the locations were low and not significant (P > 0.05). However, P values of a few locations were significant (P < 0.05) but their pairwise FST values were very poor (0.0042–0.0993), which is inadequate to recognize any local populations. Our study revealed that the presence of a single population in the Bangladesh waters with some admixtured individuals, which may contain partial genes from other populations. Most of the individuals were admixed without showing any precise grouping in the ML IQtree and Network, which might due to their highly migratory nature. Fishes from haors and small coastal rivers were not unique and no genetic differences between migratory cohorts. The hilsa shad fishery should be managed considering it as a single panmictic population in Bangladesh with low genetic diversity.

Toward Improved Comparisons Between Land‐Surface‐Water‐Area Estimates From a Global River Model and Satellite Observations

AbstractLand surface water is a key component of the global water cycle. Compared to remote sensing by satellites, both temporal extension and spatial continuity are superior in modeling of water surface area. However, overall evaluation of models representing different kinds of surface waters at the global scale is lacking. We estimated land surface water area (LSWA) using the Catchment‐based Macro‐scale Floodplain model (CaMa‐Flood), a global hydrodynamic model, and compared the estimates with Landsat at 3″ resolution (∼90 m at the equator) globally. Results show that the two methodologies show agreement in the general spatial patterns of LSWA (e.g., major rivers and lakes, open‐to‐sky floodplains), but globally consistent mismatches are found under several land surface conditions. CaMa‐Flood underestimates LSWA in high northern latitudes and coastal areas, as the presence of isolated lakes in local depressions or small coastal rivers is not considered by the model's physical assumptions. In contrast, model‐estimated LSWA is larger than Landsat estimates in forest‐covered areas (e.g., Amazon basin) due to the opacity of vegetation for optical satellite sensing, and in cropland areas due to the lack of dynamic water processes (e.g., re‐infiltration, evaporation, and water consumption) and constraints of water infrastructure (e.g., canals, levees). These globally consistent differences can be reasonably explained by the model's physical assumptions or optical satellite sensing characteristics. Applying filters (e.g., floodplain topography mask, forest and cropland mask) to the two datasets improves the reliability of comparison and allows the remaining local‐scale discrepancies to be attributed to locally varying factors (e.g., channel parameters, atmospheric forcing).

Cast netting new species: Integrative taxonomy of emDistichodus/em emnotospilus/em (Characiformes: Distichodontidae) discovers new species and overlooked areas of endemism in Central Africa.

Distichodus notospilus was described from the Ogooué River and is considered to occur throughout the Lower Guinea ichthyofaunal province and the western tributaries of the middle and lower Congo River. Recent expeditions in Equatorial Guinea collected D. notospilus specimens in the Mbini River drainage and the Mbia River; a small coastal river that is located between the Ntem and Mbini river drainages. Detailed morphological analyses and multilocus molecular analyses confirm that these two populations are distinct from one another. Topotypic populations of D. notospilus were included in the analyses and demonstrated that populations in the Mbini and Mbia rivers are distinct and these two new species are described herein. Distichodus microps sp. nov. is endemic to the Mbia River drainage and is distinguished from D. notospilus in having more scales along the lateral line (41, rarely 40 versus 37-39, rarely 40), a nearly inferior mouth versus subterminal in D. notospilus, a curved posterolateral margin of the opercle versus straight in D. notospilus, a smaller eye (56.7-80.4 versus 70.1-104.3 % of snout length), and a less prominent elongated spot at the base of the caudal fin. Distichodus mbiniensis sp. nov. is endemic to the upper Mbini River drainage and distinguished from D. notospilus in having more scales along the lateral line (41-42, rarely 40 versus 37-39, rarely 40), a much less prominent elongated dark spot at the base of the caudal fin, and a shorter dorsal fin (21.4-27.2 versus 22.7-34.2% standard length). Distichodus microps is distinguished from D. mbiniensis in having a shallower body (usually six scales from lateral line to the pelvic fin versus seven), fewer anal-fin rays (usually 12 total rays versus 13 or 14), a more inferior mouth, a deeper and longer caudal peduncle, a smaller eye, and differences in several features associated with the head. In addition to the two new species described this study also revealed potential undescribed diversity in the D. notospilus species complex in the Ntem River and Dja River (Congo R. basin) in Cameroon. The biogeography of these fishes in the rivers of Lower Guinea suggests that the Mbini River and smaller coastal rivers are overlooked areas of endemism. Studies of other reported widespread species will likely reveal additional diversity and further elucidate the processes promoting and maintaining freshwater diversity in Central Africa.

Filling distribution gaps: Two new species of the catfish genus Cambeva from southern Brazilian Atlantic Forest (Siluriformes, Trichomycteridae)

The fauna and flora of the Brazilian Atlantic Forest have been intensively inventoried since the 19thcentury, but some components of this rich biota are still poorly known, and some areas have been poorly sampled. Recent studies on a rich collection of mountain catfishes of the genusCambevahave revealed a high diversity of species still undescribed in the region. Here we provide formal descriptions for two of these species, found in areas inserted in a broad gap of the presently known genus distribution. The first one is endemic to small coastal river basins of Santa Catarina state, southern Brazil; it is tentatively placed in an intrageneric clade, also includingC. castroi,C. davisi,C. guareiensisandC. zonata, by all sharing the presence of a flat small process on the dorsal margin of the quadrate, laterally overlapping metapterygoid and situated just posterior to the syncondrial joint between the metapterygoid and the quadrate. Phylogenetic relationships of the second new species, endemic to the Rio Itajaí-Mirim basin, are still obscure, but it shares a derived morphology of the mesethmoid with some species of theC. baliosgroup. Although species ofCambevahave little external morphological variation when compared to other trichomycterine groups, the present study once more shows the importance of recording and using osteological characters to diagnose externally similar trichomycterine species.

Does rod catch reflect the background size structure of the sea trout stock in a small coastal river?

Does rod catch reflect the background size structure of the sea trout stock in a small coastal river?

Diversity of the southern Africa Lacustricola Myers, 1924 and redescription of Lacustricola johnstoni (Günther, 1894) and Lacustricola myaposae (Boulenger, 1908) (Cyprinodontiformes, Procatopodidae).

Through the analysis of a comprehensive database of COI sequences, with the sequencing of 48 specimens, a first insight into the genetic diversity, distribution and relationships between the southern Africa “Lacustricola” species is presented. Species from “Lacustricola” occur mainly in freshwater systems within the arid savanna, and are considered to be widely distributed in southern Africa, but most of them are data deficient taxa. Two species are redescribed, “Lacustricola” johnstoni (Günther, 1894) and “Lacustricola” myaposae (Boulenger, 1908), based on specimens collected at their respective type localities. Detailed osteological and life colouration information is presented for the first time. “Lacustricola” johnstoni was described from the Upper Shire River in Mangochi, Lake Malawi but is herein considered as widespread in the Okavango, Zambezi, southern Africa east coastal drainages and the Bangweulu in the Congo System. A sympatric similar species occurring in the Okavango is also identified. “Lacustricola” myaposae (Boulenger, 1908), was described from the Nseleni River in KwaZulu-Natal Province, South Africa and is herein considered to be endemic to the small coastal river drainages within this region. Lectotypes for both “L.” johnstoni and “L.” myaposae are designated. A new species from the Lualaba River in the Congo System, sister to “L.” macrurus is identified, and the deep bodied “L.” jubbi is considered sister taxon to a clade including “L.” johnstoni and “L.” myaposae.

&lt;span lang="EN-GB"&gt;Communities of the Bidentetea class of small coastal river valleys of the Western Pomerania (Poland)&lt;/span&gt;

The aim of work was to investigate the diversification, structure, physiognomy and floristic richness of riverside terophytes from Bidentetea tripartitae class in selected coastal river valleys. The investigates area encompassed the lower and middle section of the river valleys of Rega, Parsęta, Wieprza, Słupia, Łupawa in the Western Pomerania (Poland). 68 phytosociological records were made according to the system of Braun-Blanquet. A database was created with the help of the software Turboveg for Windows.The hierarchy classification with the MVSP package was used in order to arrange and group the collected phytosociological data and to single out the types of plant communities. In order to evaluate similarity of samples with respect to species composition the Bray Curtis was calculated and the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) was applied. Three plant communities belonging to one alliance Bidention tripartitae were identified: Bidenti-Polygonetum hydropiperis (Miljan 1933) Lohmeyer in R.Tx. 1950 nom invers., Bidentetum cernui Kobendza 1948, community with Polygonum minus, and one plant community belonging to the alliance Chenopodion glauci: Chenopodietum rubri Timar 1947.Given the natural origin of most of the patches, their structure, and the relatively small share of synanthropic species, including alien species, it should be emphasized that they constitute a spontaneous stage of succession of riparian vegetation. The presence of therophyte communities in the valleys of the coastal rivers, as well as their structure and physiognomy, testify to the preservation of their natural character.