Average Taxonomic Distinctness Research Articles

Thirty years of change: Assessing the dynamics of fish communities in Daya Bay, a semi-enclosed coastal ecosystem of the South China sea

Daya Bay is a semi-enclosed bay in the South China Sea which is a coastal ecosystem with significant ecological and economic value that is subjected to a variety of anthropogenic disturbances. However, long-term variation in fish community structure in this Bay remains uncertain. In this study, we aimed to explore the changing characteristics of fish species composition and community structure in Daya Bay during the past 30 years using data from 1989 to 2021 from bottom trawl surveys and historical literature data. As of now, a total of 544 species of fish have been identified in the Bay, belonging to 24 orders and 125 families. The structure of the fish community in the bay has changed over time. Firstly, there has been a clear decrease in the number of species and biomass of large fish. Secondly, the number of fish constituent orders and families has decreased. Moreover, both the average taxonomic distinctness and variation in taxonomic distinctness decreased from 1989 to 2021. Thirdly, there is low similarity among fishes at different time phases and distinct changes in the composition of dominant species. Present results indicate that the fish community structure in Daya Bay has tended to reflect a decline in diversity, shifts in composition, and shrinking of fish body size in the past 30 years. This study improves our understanding of fish species composition and its drivers over time in Daya Bay, providing important knowledge to support the protection and restoration of this ecosystem and the important ecosystem services it provides.

Continuous warming shifts the community pattern of periphytic protozoan fauna in marine environments

Protozoan fauna is playing an important role in the functioning of microbial food webs by transferring the flux of material and energy from low to high tropic levels in marine ecosystems. To assess effects of elevated temperature on the marine ecosystem, periphytic protozoan communities were used as the test microbial fauna, and were incubated in a temperature-controlled circulation system in a successive temperature gradient of 22 (control), 25, 28, 31 and 34 °C. The results showed that: (1) the test microbial fauna was shifted in both species composition and community structure; (2) the average taxonomic distinctness represented a clear decreasing trend, (3) while the variation in taxonomic distinctness significantly increased with increase of water temperature; and (4) the community pattern was significantly departed from an expectation when temperature increased by 12 °C. These results suggested that Protozoa may be used as a useful bioindicator of global warming in marine ecosystems.

Reconnoitre on ichthyofauna of Mahanadi River of India: shifting diversity down the river continuum and linking ecological traits with patterns in biodiversity.

Anthropogenic alterations have paramount impacts on the alpha and beta diversity of aquatic resources, and fishes are predominantly susceptible to such impacts. Mahanadi River, one of the major peninsular rivers of India, has abundant fish resources, which play a significant role in supporting the fishers' livelihoods. The exploratory study in the river conducted for three consecutive years recorded 148 species under 53 families. Cyprinids dominated the fish diversity with 41 species, followed by Bagrids (9) and Sciaenids (7). One hundred-one species under 29 families were reported from the freshwater stretch. With a total of 111 species reported under 48 families, the estuarine and tidal freshwater stretch was more speciose, due to marine migrant species which advent the estuarine and tidal freshwaters stretch for breeding and feeding purposes. Tikarpara, a conserved site within a sanctuary, was the most species-diverse as well as a species-even site. The study also recorded the extension of the distributional range of 3 fish species and also 4 exotic species from the river. The seasonal variations in diversity indicated that the deviations were not prominent in freshwater sites, whereas in tidal brackish water sites, species richness was relatively higher in post-monsoon, and species evenness was higher during monsoon. Taxonomic distinctness test showed that the average taxonomic distinctness was high for tidal estuarine locations as they harbour taxonomically distant fishes. The hierarchical clustering of sites showed the inordinate effect of river gradient and fragmentation on the fish community structure. Analyzing the key drivers of the assemblage structure of the entire river, salinity was the major deterministic factor, and within the freshwater stretch, the major influences were depth, transparency, and specific conductivity. The study concluded that, despite all of its ecological stresses, Mahanadi still supports rich fish diversity, yet there is a notable shift in the fish community structure. There is a need for integrating molecular and morphological tools for the taxonomic revision of many genera and species for proper in situ and ex situ conservation measures and to formulate future biodiversity management plans addressing to reduce the impacts of the ecological threats.

Study on the taxonomic diversity of fish in the East China Sea hairtail national aquatic germplasm resources conservation zone

The species composition and taxonomic diversity of fish in the East China Sea hairtail national aquatic germplasm resources conservation zone (EHCZ) were analyzed by average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) based on the fishery resource survey from 2009 to 2022. It was found that there are 169 species of fish that are collected in the EHCZ, belonging to 26 orders, 73 families, and 131 genera. The Δ+ of EHCZ was about 65.5 and Λ+ was about 40.2. The Δ+ has exhibited a slightly down trend over the decade, which implies a slight decrease in fish diversity. The Δ+ was highest in spring, possibly due to fish migration for spawning. Most of the Δ+ of a year fall within the 95% confidence funnel for Δ+ values and all Λ+ of a year fall within the 95% confidence funnel for Λ+ values. The indices were relatively stable and close to the expected value. Moreover, we recommend optimizing the protection period, improving fishing gear and methods, reducing bycatch and decreasing the number of fishing vessels and vessel power to restore the fish diversity.

Composition and Long-Term Variation Characteristics of Coral Reef Fish Species in Yongle Atoll, Xisha Islands, China.

Yongle Atoll was the largest atoll in the Xisha Islands of the South China Sea, and it was a coral reef ecosystem with important ecological and economic values. In order to better protect and manage the coral reef fish resources in Yongle Atoll, we analyzed field survey data from artisanal fishery, catches, and underwater video from 2020 to 2022 and combined historical research to explore the changes in fish species composition and community structure in Yongle Atoll over the past 50 years. The results showed that a total of 336 species of fish were found on Yongle Atoll, belonging to 17 orders and 60 families. Among them, Perciformes had the most fish species with 259 species accounting for 77.08% of the total number of species. The number of fish species in the coral reef of Yongle Atoll was exponentially correlated with its corresponding maximum length and significantly decreases with its increase. The fish community structure of Yongle Atoll changed, and the proportion of large carnivorous fish decreased significantly, while the proportion of small-sized and medium-sized fish increased. At the same time, Yongle Atoll has 18 species of fish listed on the IUCN Red List, 15 of which are large fish. The average taxonomic distinctness (Delta+, Δ+) and the variation taxonomic distinctness (Lambda+, Λ+) in 2020-2022 were lower than the historical data, and the number of fish orders, families, and genera in Yongle Atoll has decreased significantly, which indicates that the current coral reef fish species in Yongle Atoll have closer relatives and higher fish species uniformity. In addition, the similarity of fish species in Yongle Atoll was relatively low at various time periods, further proving that the fish community structure has undergone significant variation. In general, due to multiple impacts, such as overfishing, fishing methods, environmental changes, and habitat degradation, the fish species composition of Yongle Atoll may have basically evolved from carnivorous to herbivorous, from large fish to small fish, and from complexity to simplicity, leaving Yongle Atoll in an unstable state. Therefore, we need to strengthen the continuous monitoring of the coral reef ecosystem in Yongle Atoll to achieve the protection and restoration of its ecological environment and fishery resources, as well as sustainable utilization and management.

Taxonomic diversity of the macrobenthos and its relationship with environmental factors in the Huanghe River (Yellow River) estuary and adjacent seas, China

Data on the macrobenthos, bottom seawater, and sediment from 26 sampling stations in the Huanghe River estuary and adjacent seas in China, were collected in June 2020. Community structure, species diversity, taxonomic diversity of the macrobenthos, and the relationships of these variables with environmental factors were analyzed. The funnels and contours of average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) were used to indicate the disturbance status of the estuary seas. These findings revealed differences in macrobenthic community structure and biodiversity between the estuary and the adjacent seas. A total of 88 macrobenthic species were collected in the Huanghe River estuary and its adjacent seas. Abundances in the estuary, Section C, and Section D were 60 ind. m−2, 183 ind. m−2, and 320 ind. m−2, respectively, The biomass in the estuary, Section C, and Section D was 6.74 g·m−2, 15.72 g·m−2, and 9.07 g·m−2, respectively. There were significant differences in the number of species and their abundances between the estuary and adjacent seas (p < 0.01). Glycinde bonhourei, Sternaspis scutata, Moerella hilaris, Liljeborgia serrata, Iphinoe tenera, and Lineus sp. were the dominant species. The community dissimilarity of the estuary and adjacent seas reached >79.66% (p = 0.001). The results of k-means clustering analysis showed that the macrobenthic community could be divided into three types. High Margalef richness index (d) and Shannon–Wiener diversity index (H′) values were observed in the northern portion of the estuary and the seas in Laizhou Bay. The theoretical mean values of Δ+ and Λ+ were 90.8 and 267.7, respectively. High values of Δ+ were observed in Section A2-B2-C2-D2 where the communities were distantly related. Low values were observed in Laizhou Bay. The distribution of Λ+ was the complete opposite of that of Δ+. Deviations in the 95% confidence interval were observed at five stations (A2, A3, B1, B2, and D2). The northern sea of the Huanghe River estuary was disturbed. Spearman correlation analysis showed that ∆ was positively correlated with total organic carbon, heavy metals, fine silt, and clay. Heavy metal and TOC in the Huanghe River estuary and adjacent seas may be positively correlated with the reproduction of opportunistic species.

Preliminary studies of the tardigrada communities from a polymetallic nodule area of the deep South China Sea

Knowledge about marine tardigrades from the South China Sea is very scarce, with only four species from shallow waters recorded to date. The present study investigated the structure and diversity of tardigrade communities from the deep sea (1517-1725 m) at 8 stations in a polymetallic nodule area of the northern South China Sea. A total of 151 arthrotardigrades were collected belonging to 11 genera (Angursa, Batillipes, Coronarctus, Euclavarctus, Exoclavarctus, Halechiniscus, Moebjergarctus, Raiarctus, Rhomboarctus, Tanarctus and Tholoarctus), representing 17 species. Two Angursa species (Angursa sp. 4 and Angursa sp. 3) were the most abundant (25.2% and 14.6%, respectively), followed by Moebjergarctus sp. (13.9%). Specimens were mostly (90.7%) distributed in the upper layer of the sandy-mud sediment (0-1 cm). The SIMPROF test showed that the composition of tardigrade communities at all stations was not significantly different. At different stations, the number of species, Shannon-Wiener diversity index and Pielou’s evenness index ranged from 4 to 10, 1.94 to 2.87, and 0.75 to 1.00, respectively. The average taxonomic distinctness (Δ+) ranged from 72.50 to 90.00, and the variation in taxonomic distinctness (Λ+) ranged from 316.67 to 1181.25. This study provides some basic information about the biodiversity of the marine tardigrade community in the South China Sea.

Fish diversity and assemblage in the Batticaloa lagoon, Sri Lanka.

The Batticaloa Lagoon (Sri Lanka's third-largest brackish waterbody) has suffered habitat degradation and water quality deterioration during the past 30 years due to various anthropogenic activities. Despite Sri Lanka having 40 lagoons, inventories on the lagoon ichthyofauna are rather meagre and data on fish diversity and assemblages are scarce. An assessment of fish diversity is essential to maintain the ecological stability and lagoon fisheries. This study examined the fish fauna of the Batticaloa lagoon considering the northern and southern regions of the lagoon and various depths through a 3-year survey (2017-2019) and documented the dominant and rare fish species. In addition, biodiversity measures, species assemblages and the role of environmental parameters on the distribution of fishes were documented. Various diversity indices (the Margalef richness index, the Shannon-Weiner diversity index, Pielou's evenness index, the dominance index, the taxonomic diversity index, the average taxonomic distinctness index and the total taxonomic distinctness index) were calculated. Analysis of similarities (ANOSIM) was used to examine the seasonal and regional differences in the fish assemblages. The survey showed the occurrence of 96 species belonging to 40 families and 11 orders. Ambassis gymnocephalus was the most abundant fish species (8.7% of the total number of fishes collected) followed by Etroplus suratensis (6.8%), Arius maculatus (6.1%), Gerres filamentosus (5.3%), Oreochromis niloticus (4.6%) and Gerres abbreviates (3.9%). Dasyatis uarnak (0.02%), Acanthurus gahhm (0.03%), Alectis ciliaris (0.04%) and Crossorhombus valderostratus (0.08%) were considered as rare species which constitute less than 0.1% of the total while D. uarnak was considered a doubletons species (represented twice in the whole sample of 16 stations). Two types of species assemblages, one in the northern region and one in the southern region, were evident in a dendrogram (Based on the samples were collected on each region dendrogram were plotted with respect to sites then finally dendrogram of one region pratly connected by other region) based on sample composition similarity estimated with a Bray-Curtis matrix and nonmetric multidimensional scaling plots. The Bray-Curtis dissimilarity was 59.03% between the two regions, indicating statistically significant differences in assemblages (ANOSIM R 0.801; P < 0.01). The northern region of the lagoon had a higher number of species, density, Margalef richness, Pielou's evenness, Shannon-Wiener diversity, taxonomic diversity, taxonomic distinctness and total taxonomic distinctness compared to the southern region. The northern region showed significantly higher levels of salinity and dissolved oxygen (DO) and the southern region higher temperature, turbidity, phosphates and nitrates. The best subset of biota and environmental variables [BEST(BIO-ENV)] test showed a significant relationship between fish assemblage and environmental parameters. Distance-based linear model analysis showed a significant relationship between fish assemblage and the environmental parameters salinity, temperature, pH and DO. The sequential test of this analysis showed the environmental parameters to explain about 74.9% (R2 ) of the total variation. The bioenvironmental model developed was found to be appropriate. Thirteen species were found to be influential as they explained the overall fish distribution pattern with a Spearman rank correlation of 0.951. Ten groups of coherent species were also identified in the study area. In stations having anthropogenic activities, the fish diversity was low. The fish fauna of the Batticaloa lagoon should be monitored periodically to protect the fishery resources here. An understanding of the role that environment plays in structuring the fish assemblage in the Batticaloa lagoon and locations with critical habitats will be of great importance in the conservation and management of fishery resources in this lagoon. However, as monitoring only the dominant species may fail to pick up on important impacts affecting the less common species, it should be done using diversity indices and rare fish species. Monitoring is imperative in view of the livelihood of the fishers this lagoon supports and the health of the local people, as fish is a healthy food. The fishery resources of this lagoon must be protected for posterity with appropriate management measures.

Taxonomic diversity of fishes from two coral-reef waters of the South China Sea

Context Conservation of coral-reef fishes requires an understanding of their spatial and temporal responses to climate change and anthropogenic disturbance, which also requires an understanding of patterns in their taxonomic diversity. Aims To describe the species composition, taxonomic diversity and G-F diversity-measurement index of Qilianyu Island and Meiji Reef, South China Sea, coral-reef fish assemblages. Methods Coral reef-dwelling fish were sampled in 2018 and 2019 at Meiji Reef and Qilianyu Island by using various fishing gears, identified to the lowest taxonomic category, and their taxonomic relatedness was compared at levels of class, order, family, genus and species. Key results The reef-dwelling fish fauna of this region comprises 123 species in 5 orders (dominated by Perciformes, at 78%), 22 families and 46 genera. The average taxonomic distinctness (Δ+) of Qilianyu Island fish assemblages is 55.52, and variation in taxonomic distinctness (Λ+) is 138.18; for Meiji Reef, values for Δ+ and Λ+ are 53.02 and 135.33 respectively. Conclusions High species diversity and low taxonomic diversity are important features of coral-reef fish assemblages in the South China Sea. Implications The high species diversity of reef fish in the South China Sea, along with a well-distributed assemblage of families and genera, is crucial for preserving the region’s fish biodiversity. Consequently, timely prioritisation of reef fish conservation is essential.

Fish community diversity in a coastal zone at southeastern Gulf of California, Mexico.

Although the southeast region of the Gulf of California has a high fish diversity, due to the high biological productivity, the coastal area of Nayarit has few studies in this regard. The main objective of this work is to describe the variability of the structure of the ichthyofauna in the coastal zone of Nayarit during an annual cycle. Biological samples were collected at 10 stations during February, May, July, and December 2014. The temperature, depth, salinity, and organic material and carbonates in sediments were also recorded. The analysis of diversity includes three facets: ecological, taxonomic, and functional. A total of 82 species belonging to 56 genera, 31 families, 11 orders, and two classes were identified. The most abundant species included Selene peruviana, Stellifer wintersteenorum, Cathorops sp., and Larimus argenteus. Of the total of identified species, 62% were considered as rare according to their abundance and frequency. Although the environmental variables analyzed were variable, all diversity indices did not reveal an evident spatio-seasonal pattern. Likewise, most values of average taxonomic distinctness presented the expected values. However, some values showed a low taxonomic diversity. The indices of functional diversity showed a stable functional richness and redundancy in the attributes of the species.

Do Changes in the Length of the List of Reference Species Influence the Results of the Average Taxonomic Distinctness?

Do Changes in the Length of the List of Reference Species Influence the Results of the Average Taxonomic Distinctness?

Response of marine amphipods to sediment variables (Chabahar Bay- Iran): A step toward localizing amphipod-based bioindices

Chabahar Bay will undergo industrial and coastal pressures according to the government plan to develop the Makran coasts. Therefore, knowing its biological community as well as their possible interactions with environmental variables, before and after coastal development, is important. The amphipod community structure and their response to the structural and contaminant parameters of the sediment include: granulometry, total organic matter (TOM) overloading, heavy metal contamination based on the Pollution Load Index (PLI) and polycyclic aromatic hydrocarbons (PAHs) during post monsoon season of 2017 were investigated from 19 stations. Traditional diversity and taxonomic distinctness indices were calculated. Multivariate analysis revealed the main role of sediment grain size and depth in shaping amphipod community structure. Consequently, two specific ecological niches were determined: species that prefer non-muddy substrates; and those dwelling in muddy or muddy sandy biotopes. No correlation was found between the Shannon diversity (H’), the average taxonomic distinctness indices (Δ+) together and both with contamination parameters. The Δ+ funnel plot well separated under-stressed stations from the healthy ones. The presence of only Ampelisca congeners in under-stressed stations revealed the tolerant nature as well as species-specific response of the genus to anthropogenic impacts. Considerable tolerant response (P > 0.05, r2 = 0.4) of A. zamboangae to PAHs; A. persicus to TOM were observed. High concentration of nickel (Ni) in the studied area already stated due to erosion of ophiolite units from Makran Mountains. The significant correlation of the recently described Iranian species A. lowryi with Ni assumes that it is a native species that is well adapted to the geological conditions of the seabed. Instead Urothoe platydactyla can be considered as early warning signal for PAHs, TOM, Ni and cadmium (Cd) contamination particularly for non-muddy substrates. Our findings help to localize common biotic indices (e.g. AMBI, BENTIX, and BOPA) for studied area through correctly assignment of amphipods to the sensitive/tolerant ecological groups. Finally, we state that in the current situation of Chabahar Bay, in which no special industrial complexes have been established, any sediment-disrupting activity (i.e. sedimentation, dredging, trawling) affects its amphipod communities more than chemical pollutants.

Multivariate approaches to assess the drivers of benthic macroinvertebrate communities and biotic indices in a highly urbanized fluvial-estuarine system

Urban estuaries are amongst the most severely altered systems worldwide and undergo a wide range of ecological crises such as habitat destruction, nutrient enrichment and hydrodynamic alterations, resulting in an irreversible loss of biodiversity as well as a further environmental deterioration. Differentiating the main driving forces of multiple stressors is of utmost importance to provide beneficial insights for environmental restoration and management. In the present study, comprehensive investigations and multivariate approaches were performed to reveal the spatio-temporal variations of benthic macroinvertebrate communities and biotic indices and to examine their responses to environmental alterations within a highly urbanized fluvial-estuarine system. The nutrient levels gradually dwindled from urban fluvial sections to estuarine sections, meanwhile, macroinvertebrate community composition and dominant species considerably varied along the estuarine gradient. Overall, environmental parameters, macroinvertebrate communities and biotic indices varied significantly among sections and seasons. Salinity, dissolved oxygen, ammonia, total nitrogen, chemical oxygen demand and total organic carbon significantly explained the spatio-temporal variations of macroinvertebrate communities and biotic indices. Despite some inconsistencies in assessment outcomes, all indices revealed that urban fluvial sections of the Pearl River Estuary were disturbed, more or less severe depending upon the index. Among the tested indices, AMBI, BENTIX and average taxonomic distinctness (Δ+) presented better performance in assessing the ecological quality status and showed high responses to environmental stresses. More importantly, the relative contribution of water parameters vastly overrode sediment parameters in shaping variations of macroinvertebrate communities and biotic indices, demonstrating that anthropogenic activities (e.g., discharge of municipal and industrial sewage) directly altered the benthic community composition and diversity.

Assessment of the Ecological Status of Rongjiang Estuary (China) Under Human Pressure, Using Biotic Indices Based on Benthic Macroinvertebrates

Rongjiang River, the second largest river system in Guangdong Province, flows through the main urban areas of Jieyang and Shantou cities before reaching the South China Sea. Human activities in the surrounding area pose significant threats to this aquatic ecosystem. The ecological status (ES) of the benthic ecosystem of the Rongjiang River estuary has not yet been conducted using indices based on the macrobenthic fauna, which is important for evaluating environmental health. Here, we used four biotic indices (the AZTI’s Marine Biotic Index (AMBI) and Multivariate AZTI’s Marine Biotic Index (M-AMBI), and taxonomic distinctness indices (average taxonomic distinctness Δ+ and variations in taxonomic distinctness Λ+) to appraise the current ES of benthic communities in Rongjiang estuary. Samples were taken from 11 sampling sites located in six general regions: western aquaculture zones, aquaculture zones, Hanjiang River water channel, Shantou City, Shantou Port, and near the ocean. The benthic ecosystem of this estuary is greatly disturbed: the ES of the aquaculture zones and the sites near the Hanjiang River water channel, Shantou City, and close to the ocean was poorer compared with that of other areas; ES was also poorer in winter than in summer. Generalized linear models revealed that Shannon-Wiener index was negatively correlated with dissolved inorganic nitrogen (p &amp;lt; 0.01), M-AMBI was negatively correlated with temperature and dissolved inorganic nitrogen (p &amp;lt; 0.05 and p &amp;lt; 0.01, respectively), and Λ+ was negatively correlated with pH (p &amp;lt; 0.05). The AMBI, M-AMBI, Δ+, and Λ+ indices were suitable for assessing the ES of the benthic ecosystem in an anthropogenically disturbed estuary.

Effects of river-lake disconnection and eutrophication on freshwater mollusc assemblages in floodplain lakes: Loss of congeneric species leads to changes in both assemblage composition and taxonomic relatedness

River floodplain ecosystems host one of the highest freshwater molluscan biodiversity on Earth. However, multiple human disturbances, such as loss of hydrological connectivity and deterioration of water quality, are seriously threatening most floodplain lakes throughout the world. Given the high imperilment rate of freshwater molluscs but the scarcity of studies examining the anthropogenic effects on this fauna, we test the response of mollusc assemblages to river-lake disconnection and eutrophication in 30 lakes in the Yangtze River floodplain, China. The species richness of entire Mollusca, Gastropoda and Bivalvia and 6 dominant families were all much lower at disconnected lakes than that in connected lakes, and decreased with increasing water eutrophication. The assemblage structure differed significantly among four lake groups for datasets based on entire Mollusca, Gastropoda and Bivalvia, indicating the serious impacts of hydrological disconnection and eutrophication. Moreover, the connected lakes showed significantly lower values of average taxonomic distinctness (Δ+) but higher values of variation in taxonomic distinctness (Λ+) than disconnected lakes. Such variations were triggered by the extirpation of congeneric and endemic species (mainly from families Unionidae and Viviparidae), which giving a waring of the loss of mollusc endemism in this region. In general, the present study showed that river-lake disconnection and deterioration of water quality resulted in serious biodiversity declines of both gastropods and bivalves in the Yangtze River floodplain lakes. A systematic approach including restoration of river-lake connectivity and habitats and improvement of water quality should be implemented in the conservation planning in this large river floodplain.

Patterns of richness, diversity and abundance of an odonate assemblage from a tropical dry forest in the Santiago Dominguillo Region, Oaxaca, México (Insecta: Odonata).

A study on the patterns of richness, diversity and abundance of the Odonata from Santiago Dominguillo, Oaxaca is presented here. A total of 1601 specimens from six families, 26 genera and 50 species were obtained through monthly samplings of five days each. Libellulidae was the most diverse family (21 species), followed by Coenagrionidae (19), Gomphidae (4) and Calopterygidae (3). The Lestidae, Platystictidae and Aeshnidae families were the less diverse, with only one species each. Argia was the most speciose genus with 11 species, followed by Enallagma, Hetaerina, Erythrodiplax and Macrothemis with three species each and Phyllogomphoides, Brechmorhoga, Dythemis, Erythemis and Orthemis with two species each. The remaining 17 genera had one species each. Argia pipila Calvert, 1907 and Leptobasis vacillans Hagen in Selys, 1877 were recorded for the first time for the state of Oaxaca. We also analysed the temporal patterns of taxonomic and phylogenetic divergence for the Santiago Dominguillo Odonata assemblage: the Shannon diversity value throughout the year was 21.07 effective species, while the Simpson diversity was 13.17. In general, the monthly phylogenetic divergence was higher than expected for taxonomic distinctness, and lesser for average taxonomic distinctness. Monthly diversity, evenness and taxonomic divergence showed significant positive correlations (from moderate to strong) with monthly precipitation values. The analysis of our results, however, indicates that an increase in rainfall not only influences the temporal diversity of species, but also the identity of supraspecific taxa that constitute those temporal assemblages, i.e. there is an increase in temporal phylogenetic divergence.

Effects of latitude, host body size, and host trophic guild on patterns of diversity of helminths associated with humans, wild and domestic mammals of Mexico.

Parasites are strictly associated with their hosts and present a great diversity of life histories, often resulting in different diversity patterns than those observed in free-living species. However, ecological approaches have detected that, in some cases, mammal-associated helminths respond similarly to non-parasitic species in terms of diversity patterns. Using 2200 recorded interactions, we analysed the diversity patterns of helminths (Acanthocephala, Nematoda and Platyhelminthes) harbored by humans, wild and domestic mammals of Mexico, depending on latitude, host body mass and trophic guild (carnivore, herbivore, insectivore, omnivore), considering helminth richness and average taxonomic distinctness, and host phylogenetic diversity and phylogenetic clustering. Latitude was positively correlated with the average taxonomic distinctness encompassing the three parasite phyla and nematodes. Northern latitudes had less taxonomically related parasite assemblages. Host body mass had a significant negative relationship with the average taxonomic distinctness of acanthocephalans and the richness of helminths associated to wild hosts. The omnivore hosts had greater parasite richness, while insectivores had a less taxonomically related parasite assemblage and herbivores had a more heterogeneous parasite assemblage. Our results highlight the importance of incorporating different dimensions of diversity, such as average taxonomic distinctness and to consider the composition of parasite assemblages to better understand their diversity patterns.

Ecological Quality Status (EcoQs) of Chabahar sub-tropical bay based on multimetric macrobenthos-indexes approach: Response of bio-indexes to sediment structural/pollutant variables

The present study aims to test the applicability of the macrobenthos indexes (AMBI, M-AMBI, BENTIX, BOPA; Shannon (H′);average taxonomic distinctness (Δ+), variation in taxonomic distinctness (Λ+) and total taxonomic distinctness (sΔ+) to assess the EcoQs of Chabahar Bay. Sampling was performed in the pre-monsoon period of 2017 from 19 stations. Five sediment texture/pollutant variables include grain size, total organic matter (TOM), PAH, heavy metal Pollution Load Index (PLI) and depth were also measured. Distribution pattern of macrobenthos as well as inter/intra relationship of the biotic and abiotic variables was investigated through multivariate statistical approaches. The Pearson and Rosenberg model was used to determine critical limit of TOC to reduce species richness, and as a criterion to select under-stressed stations. PCA analysis of all of indexes was used to evaluate the EcoQs of the polluted, suspected polluted or healthy stations. DistLM analysis showed that the sediment grain size followed by depth and TOM were main variables that significantly determined the distribution pattern of macrobenthos. Sensitive/tolerant indexes showed 84% full agreement as “acceptable” on most stations (including low-high TOC), while H′ values assessed all stations as “unacceptable”. The funnel plot of Λ+ could identify disturbed (high TOC) muddy stations, but was not a strong indicator of TOC disturbance for non-muddy stations. Among all indexes used in this study only the Λ+ showed significant correlation with PAH, TOM and sediment grain size. We believe that the Λ+ index works well in muddy substrates if the stress type is TOM overloading or PAH pollution. However this index alone does not make good judgment on the EcoQs of the studied area, so we recommend multimetric use of different indexes. The findings of the present study suggest that the physicochemical composition of sediment plays a key role in the distribution of macrobenthos and subsequently EcoQs assessment of Chabahar Bay, therefore, any anthropogenic activity affecting sediment could cause dramatic changes in macrobenthos assemblages.

Taxonomic distinctness poorly reflects floristic quality in a wetland study system

Biomonitoring typically uses taxonomic diversity information while ignoring phylogenetic diversity. Evolutionary relatedness may offer deeper insight to how local assemblages relate with human disturbance and ecological degradation. Degradation of floristic quality may filter species with similar evolutionary traits, whereas intact floristic quality may limit phylogenetic clumping and increase representation of more distantly related taxa. We tested this hypothesis using average taxonomic distinctness (AvTD) and measures of floristic quality (mean ecological conservatism, native species richness, percent exotic species) in vascular plant assemblages of 115 wetlands in the US southern plains. In line with the hypothesis, we observed positive correlations with conservatism (r = 0.28, P = 0.0007) and native richness (r = 0.24, P = 0.0018) and a negative correlation (r = −0.21, P = 0.0169) with exotics, but the plotted relationships looked obscure. A strongly skewed AvTD distribution revealed a clear gradient in lower than expected AvTD. Responses along this gradient covaried with native richness (quadratic model R2 = 0.75) but showed no pattern with conservatism and a weak response to exotics. These results suggest that native richness has potential to predict lower than expected AvTD values. However, attributing these values to degraded floristic quality requires caution when richness is driven by sampling effects such as species-area relationships or has a non-linear relationship to human disturbance. Given the vague correlations and ambiguity of richness, plant taxonomic distinctness may not provide a clear bioindicator for wetlands. More work is needed to elucidate how evolutionary structure may play into bioassessment, which traditionally has been phylogenetically neutral.

Utilization of species checklist data in revealing the spatial distribution of fish diversity.

Marine fish species checklists from six Chinese coastal waters were combined for the analysis of taxonomic diversity. The Genus-Family index (G-F index) ranged between 0.39 and 0.84, which generally indicated a decreasing trend with increasing latitude, with the exception of the southernmost area. Average taxonomic distinctness showed a slight increasing trend from northern to central study areas, but whether the taxonomic distinctness indices represent a latitudinal gradient of biodiversity requires further study. The multivariate analysis revealed a distinct latitudinal variation in fish assemblages. These results indicate that species checklist data are helpful in understanding the diversity distribution of fish species in the coastal zone. The potential of a species inventory should be exploited to fully understand biodiversity.