Benthic Macroinvertebrate Species Research Articles

Bubbling trouble: Effects of supersaturated water on benthic macroinvertebrates

AbstractThe saturation of total dissolved gases (TDG) in water remains around 100%. Certain circumstances can lead to TDG values exceeding 100%, resulting in TDG supersaturation (TDGS). TDGS above about 110% can be toxic to animals that rely on water for gas exchange. However, saturation beyond 200% can occur in freshwater downstream of dams and hydroelectric power plants. Despite its impact, TDGS is often overlooked as a hazard to aquatic life, particularly for benthic macroinvertebrates. This study aimed to examine the effects of TDGS on nine species of benthic macroinvertebrates. We used replicated tank studies to manipulate TDGS levels from 100% to 120% and investigated the overall survival and species‐specific effects on survival and buoyancy. We also present a summary on the effects of TDGS on invertebrate species previously tested. The results indicate that seven of nine species exhibited increased buoyancy when exposed to TDGS, causing them to float on the water surface. Additionally, a Cox Proportional Hazards model revealed a significant effect of TDGS on the survival of the macroinvertebrates. The sensitivity towards TDGS varied greatly among species of benthic macroinvertebrates, and significant species‐specific effects were only observed for Isoperla grammatica, Baetis rhodani and Asellus aquaticus. Among these, the two latter species showed clear dose‐related effects caused by TDGS, enabling the assessment of LT50 (time required to kill half of the tested population). B. rhodani was most sensitive with a LT50 of 3.7 days at 119% TDGS. Both species had visible air bubbles under the exoskeleton. Our findings highlight that direct and indirect effects on benthic macroinvertebrates can occur even at low to moderate levels of gas supersaturation, likely causing reduced density, decreased species diversity and altered species composition. The emerging evidence strongly supports the implementation of regulations on TDGS in freshwaters.

Biomonitoring of the confluence of the Maguaca and Yuna rivers, Cotui, Dominican Republic

The degradative processes such as mining cause loss of species, forest cover, ecosystem services and contaminate bodies of water. Under this problem, the behavior of the water quality of the confluence of the Maguaca and Yuna rivers, in the municipality ofCotuí, Dominican Republic, associated with mining activities, was determined. The research was carried out during two moments: December 2020 (t1) and February 2021 (t2). For this, a deterministic sampling of seven equidistant points in the Maguaca River, and two in the Yuna River, was carried out at t1 in rainy season and t2 in dry season. In addition, the presence of benthic macroinvertebrate species was analyzed as indicators of water quality according to the BMWP-Cub method, and the composition and structure of the riparian vegetation was determined. Likewise, the spatial behavior of the physicochemical variables of water such as potential hydrogen (pH), salinity, electrical conductivity (EC), turbidity, biological oxygen demand (BOD), nitrates (NO3-), chemical oxygen demand (COD), phosphates (PO43-), temperature, dissolved oxygen (O2D), total organic carbon (TOC), and iron concentration (Fe). Water of critical quality (very contaminated) was obtained in the upper part and very critical quality (heavily contaminated) in the lower part, at both times. It is recommended to strengthen monitoring policies for environmental, socioeconomic and health effects.

The drivers of benthic macroinvertebrates communities along a subtropical river system: Sediments chemistry or water quality?

AbstractImpacts of metal pollution, either on water or in sediments within aquatic systems have been a serious challenge globally. Little is known about the ecological impacts of metal pollution on benthic macroinvertebrates species in sub–tropical river systems. The aim of this study was to examine benthic macroinvertebrates community composition in relation to sediment metal concentrations and other physicochemical variables in the Mutshundudi River system. Benthic macroinvertebrates sampling and community composition analysis, sediment collection, processing, metal analysis and assessment of water variables in the river system were done across two seasons at 12 sampling sites. The river was categorized into three segments: upstream, midstream and downstream. The results from geo‐accumulation (Igeo) values showed that sediments were loaded with Na, Zn, and B in all river segments. In comparison with South African water quality guidelines for aquatic ecosystems, water quality ranged from good at upstream sites because of low anthropogenic activities to very poor in downstream sites because of high anthropogenic activities. Sediments from the Mutshundudi River showed significant differences on high concentrations of metals (i.e., Mg, K, Na, and Cu) and seasonal variations. Both water quality and sediment chemistry were considered the driving factors of benthic macroinvertebrates, since species densities and composition reduced with a decline in water and sediment quality during both cool–dry and hot–wet seasons. Continuous build‐up of the metal contaminants, such as Mg, K, Na, and Cu in river sediments may pose adverse impacts on macroinvertebrate community structure.

Aquatic and sediment ecotoxicity data of difenoconazole and its potential environmental risks in ponds bordering rice paddies

Difenoconazole has a widespread agricultural use to control fungal diseases in crops, including rice. In edge-of-field surface waters the residues of this lipophilic fungicide may be toxic to both pelagic and benthic organisms. To allow an effect assessment we mined the regulatory and open literature for aquatic toxicity data. Since published sediment toxicity data were scarce we conducted 28 d sediment-spiked toxicity test with 8 species of benthic macroinvertebrates. Ecotoxicological threshold levels for effects were assessed by applying the species sensitivity distribution approach. Based on short-term L(E)C50’s for aquatic organisms from water-only tests an acute Hazardous Concentration to 5% of the species (HC5) of 100 µg difenoconazole/L was obtained, while the HC5 based on chronic NOEC values was a factor of 104 lower (0.96 µg difenoconazole/L). For benthic macroinvertebrates the chronic HC5, based on 28d-L(E)C10 values, was 0.82 mg difenoconazole/kg dry weight sediment. To allow a risk assessment for water- and sediment-dwelling organisms, exposure concentrations were predicted for the water and sediment compartment of an edge-of-field pond bordering rice paddies treated with difenoconazole using the Chinese Top-Rice modelling approach, the Chinese Nanchang exposure scenario and the Equilibrium Partitioning theory. It appeared that in the vast majority of the 20 climate years simulated, potential risks to aquatic and sediment organisms cannot be excluded. Although the HC5 values based on laboratory toxicity data provide one line of evidence only, our evaluation suggests population- and community-level effects on these organisms due to chronic risks in particular.

Before and after closed season for beach seine fishing in Ghana: Impact on benthic macroinvertebrates species diversity indices

AbstractBeach seine fishery provides a means of livelihood to many households in Africa and it is widely practiced in the coastal communities of Ghana due to the relatively cheaper operational cost. However, the small mesh sizes of beach seine nets and fishing activities that involve dragging a net through the nearshore seabed tend to destroy fish breeding grounds and capture juvenile fish and non‐target benthic macroinvertebrates, which get discarded. This study investigated the impact that before and after closed season for beach seine fishing had on macroinvertebrates species diversity indices at two Ghanaian beaches with different fishing pressures. The study was carried out at OLA and Sisimbo Beaches located in the Central Region of Ghana, taking advantage of the statutory 1‐month national fishing closed season in July 2022. Six (6) replicate sediment samples were taken at each beach after landing by beach seine fishers every month for 6 months, from April to June, and August to October, representing before and after closed season, respectively. Benthic macroinvertebrates were retrieved from the samples using appropriate protocols and subjected to indirect (Shannon, Simpson, Rényi) and direct (species abundance models, species accumulation models, multivariate statistics) measures of species diversity analyses. The indirect species diversity indices increased monotonically the following 2 months after closed season but reduced in the third month after closed season at both beaches. Conversely, the direct measures of diversity indices revealed that closed season for beach seine fishing improved species numbers and richness at both study beaches. This is the first report on the impact of a closed season on macroinvertebrates in any African country.

Climate-associated variation in the drivers of benthic macroinvertebrate species-area relationships across shallow freshwater lakes.

The island species-area relationship (ISAR) describes how species richness increases with increasing area of a given island or island-like habitat, such as freshwater lakes. While the ISAR is one of the most common phenomena observed in ecology, there is variation in both the form of the relationship and its underlying mechanisms. We compiled a global data set of benthic macroinvertebrates from 524 shallow freshwater lakes, ranging from 1 to 293,300 ha in area. We used individual-based rarefaction to determine the degree to which ISAR was influenced by mechanisms other than passive sampling (larger islands passively sample more individuals from the regional pool and, therefore, have more species than smaller islands), which would bias results away from expected relationships between rarefied species richness (and other measures that capture relative abundances) and lake area. We also examined how climate may alter the shape of the ISARs. We found that both rarefied species richness (the number of species standardized by area or number of individuals) and a measure of evenness emphasizing common species exhibit shallow slopes in relationships with lake area, suggesting that the expected ISARs in these lakes most likely result from passive sampling. While there was considerable variation among ISARs across the investigated lakes, we found an overall positive rarefied ISAR for lakes in warm (i.e. tropical/subtropical) regions (n = 195), and in contrast, an overall negative rarefied ISAR in cool (i.e. north temperate) lakes (n = 329). This suggested that mechanisms beyond passive sampling (e.g. colonization-extinction dynamics and/or heterogeneity) were more likely to operate in warm lakes. One possible reason for this difference is that the area-dependent intensity of fish predation, which can lead to flatter ISARs, is weaker in warmer relative to cooler lakes. Our study illustrates the importance of understanding both the pattern and potential processes underlying the ISARs of freshwater lakes in different climatic regions. Furthermore, it provides a baseline for understanding how further changes to the ecosystem (i.e. in lake area or climate) might influence biodiversity patterns.

Effects of an Introduced Benthivorous Fish on Macroinvertabrates Diversity in a Semiarid Shallow Lake

The Cyrinus carpio Linnaeus, 1758 (common carp) is a widely introduced species for commercial purposes. However, its detrimental effects on lakes and reservoirs, such as a decrease in water quality, abundance and richness of macrophytes, and macroinvertebrate abundance, are also known. In this study, we investigated the effect of common carp introduction on the macroinvertebrate community in a shallow lake in the Brazilian semiarid region. The study in Panati lake took place between 2002 and 2008 with the introduction of common carp in 2004. Shallow lakes from Our results showed that after common carp introduction, there was a significant reduction in the richness and diversity of the macroinvertebrate community, as well as an increase in the dominance of certain groups, such as chironomids. The decrease in richness and diversity is likely a result of the decline in abundance of key dominant benthic groups and species, such as the gastropods Pomacea lineata (Spix, 1827), Biomphalaria straminea (Dunker, 1848), Aplexa marmorata (Guilding, 1828) and Plesiophysa ornata (Haas 1938), oligochaetes, and ostracods, as well as several insect families. This decline may also lead to increased variability (destabilizing effect) among gastropods, annelids, and crustaceans, as well as an increase in the variability of richness and diversity among benthic macroinvertebrate species

Using benthic macroinvertebrates as bioindicators to evaluate the impact of anthropogenic stressors on water quality and sediment properties of a West African lagoon

This study aimed to investigate the impact of anthropogenic stressors (landfilling, navigation for transport of goods, cooling in fossil fuel, urbanization, industrial expansion, agriculture activities, and recreational activities) on environmental variables, microbiological quality, and sediment properties using benthic macroinvertebrates as a bioindicator within Lagos Lagoon, Nigeria. Four (4) sampling stations were established with respect to their importance/anthropogenic activities within the Lagos Lagoon. Surface water, bottom substrates, and benthic macroinvertebrate fauna samples were collected bimonthly from each sampling station for a year and analyzed using appropriate standard methods and procedures. The highest pH range of 7.96–8.01 (7.98 ± 2.35) was recorded at Site IV, while the lowest range of 6.41–7.01 (6.15 ± 1.14) was observed at Site II, and there was a significant difference (p < 0.05) among the pH mean values across the sites. High values of salinity, chloride, sodium, COD, BOD, manganese, nickel, cadmium, and nitrate were recorded among the surface water physicochemical parameters, which were above WHO (2011) permissible limits, while the high concentrations of toxic metals (Pb, Cr, Zn, and Cd) was recorded in sediment. A total of 26 species of benthic macroinvertebrates were recorded during this study, which belongs to eight (8) classes. Gastropoda recorded the highest percentage contribution of 39.12%, followed by polychaeta accounting for 30.34%, while malacostraca contributed 2.63%. The highest abundance of macroinvertebrates was recorded at Site I (256 Indiv/m2), followed by Site IV (252 Indiv/m2), and the least was observed at Site II (195 Indiv/m2). Based on the results of the physico-chemical, heavy metals, microbial quality, and macroinvertebrates assemblage obtained from this study revealed the adverse effect of anthropogenic activities on water quality degradation. It plays a significant role in the distribution and diversity of benthic macroinvertebrates in an aquatic environment.

Genus-level macroinvertebrate methods limit the conservation coverage afforded aquatic species

Benthic macroinvertebrate protocols, in the United States, have been integral in the implementation of the Clean Water Act (33 U.S.C. §1251 et seq. (1972)). The methods in these protocols are designed to describe patterns of biological water quality and ecological condition relevant to legislative oversight, and require a tradeoff between taxonomic precision and protocol simplicity. The global similarity of ecological and evolutionary responses to the challenges of life in flowing waters, by stream organisms, has greatly facilitated the development and implementation of biological data from freshwater mussels, fishes and aquatic insects into streamlined regulatory frameworks. Unfortunately, the factors that expedite the use of benthic data into ecological descriptions sufficient for regulatory processes (taxonomic generalizations, standardization of sampling procedures to focus on a narrow subset of available habitats) also limit the utility of these methods in the conservation of benthic macroinvertebrate species (the large majority of which are insects). Using simple hypothetical simulations, some examples from a taxonomic and ecological database of one state in the USA (Illinois), and data from a large-scale inventory of aquatic insect species in a network of US National Parks, I illustrate how these methods are limited in their ability to effectively describe ecological patterns relevant to the conservation of aquatic insect species. I identify, challenge, and explore three basic assumptions implicit to the genus- and family-level identification methods widely used in freshwater benthic science, then discuss how the failure of these assumptions may create empirical, theoretical and philosophical obstacles to the interpretation of data and certainly hinder the conservation of species. I offer some hopeful suggestions for improving aquatic insect species conservation that are within the reach of all benthic freshwater ecologists.

Impact of agricultural practices on ecosystem health of lagoons: a case study of the Keta Lagoon Complex in Ghana, West Africa

The paper reports on the current ecological health of the Keta Lagoon Complex by analyzing a suite of physical, chemical, and biological environmental conditions prevailing within it. Results are discussed in relation to the main human activity (i.e., agriculture) prevailing in its catchment. The current water quality of the lagoon has declined compared to data collected 20years ago with elevated levels in parameters such as nitrate, phosphate, turbidity, and temperature. Secchi disk depth, salinity, and dissolved oxygen levels in the lagoon have decreased. More than 60% of the total area of the lagoon is predicted to be currently unsuitable to support aquatic life. The Carlson's TSI estimated for the various zones of the lagoon ranged between 72.40 and 80.61 depicting a highly eutrophic lagoon, with about 90% of the total area studied confirmed to be experiencing some degree of eutrophication. The plankton index of biotic integrity also yielded high values of between 3 and 6 in most areas of the lagoon, thereby affirming the poor health of the lagoon. The diversity of phytoplankton and benthic macroinvertebrate species in the lagoon has reduced significantly in the last two decades with about 11 genera of phytoplankton missing in the present study. Benthic macroinvertebrate assemblage richness, evenness, and diversity have decreased from 3.6, 2.0, and 5.8 in 2008 to 1.2, 0.8, and 1.7 respectively, in the present study. Overall, the health of the Keta Lagoon remains poorer and continues to decline with no signs of recovery.

Human-Induced Impact on the Distribution and Diversity of Benthic Macroinvertebrates and Fish Fauna in the Tropical Ikang River, Nigeria

Abstract South-eastern Nigeria’s tropical water ecosystems typically consist of mangrove swamps and riparian forests, both of which have become endangered in the last six decades. The purpose of this research was to determine the extent of human-induced impact and activities on the effect of water quality on the distribution and diversity of benthic macroinvertebrates and fish fauna in the Tropical River (Ikang). The river’s surface water, benthic macroinvertebrates, and fish fauna were sampled and identified to create a database of reference information. Twelve (12) species of benthic macroinvertebrates from two (2) phyla were identified. Station 1 had the highest benthic macroinvertebrate abundance of 58 (35.65%), while Station 3 had the lowest abundance of 52 (31.70%). Uca tangeri was the most abundant benthic macroinvertebrate with a percentage abundance of 28 (17.07%), while Dinocras sp., Macromia sp., and Gomphus sp. were the least abundant benthic macroinvertebrates with a percentage abundance of 3.66%. In addition, seven (7) fish species from six (6) families were identified. During the study, the family Claroteidae was the most abundant, while the family Carangidae was the least abundant. The temperature of the river had a positive correlation with the families Carangidae and Mugilidae, a negative correlation with the family Clupeidae, and no correlation with the family Claroteidae. Total dissolved solids (TDS) correlated positively with the families Carangidae, Mugilidae, and Clariidae, while conductivity correlated positively only with the family Sciaenidae and negatively with the families Carangidae, Mugilidae and Clariidae. The abundance and diversity of benthic macroinvertebrates and fish fauna were generally influenced by the physical and chemical characteristics of the water, the availability of food, and the extent of human impacts and activities. In order to ensure sustainable water quality and biodiversity conservation in our environment, it is necessary to manage the river and the surrounding ecosystem appropriately.

Assessment of benthic macroinvertebrates as potential bioindicators of anthropogenic disturbance in southeast Bangladesh coast.

Many human activities can greatly influence and alter the health of aquatic ecosystems. In this regard, the quantitative analysis of macroinvertebrates and their relationships with ecological variables is an effective method in environmental monitoring programs. Here, we used the benthic macroinvertebrate community as bioindicators for assessing anthropogenic impacts on coastal waters in southeast Bangladesh. Sediment samples were collected seasonally from three different sites influenced either by mangrove forests, aquaculture activity or sewage input. The indicator value index (IndVal) analysis revealed 23 species of benthic macroinvertebrates as potential bioindicators namely Enigmonia aenigmatica, Mactra chinensis and Pharella javanica of the class Bivalvia; Tubifex tubifex of the class Clitellata; Lithopoma brevispina, Bullia vittata, Pomacea maculata and Umbonium vestiarium of the class Gastropoda; Gammarus roeselii of the class Malacostraca; and Amphicteis gunneri, Amphitrite ornata, Aricidea simplex, Cirratulus cirratus, Heterospio catalinensis, Hypereteone foliosa, Lopadorrhynchus henseni, Neanthes chingrighattensis, Micronephthys oligobranchia, Nephtys hombergii, Nereis jacksoni, Nereis zonata, Polyodontes maxillosus and Stygocapitella subterranean of the class Polychaeta. Their composition across three sites varied significantly (P<0.05) due to influence of environmental conditions as inferred from redundancy analysis. Polychaeta, Gastropoda and Malacostraca were susceptible to sewage input, while Bivalvia and Clitellata were susceptible to aquaculture effluent. The results of this baseline study suggest that the identified benthic macroinvertebrate species can potentially be used to monitor anthropogenic disturbances in the marine environment.

Invasive Alien Species of Benthic Macroinvertebrates and Fish in the Bulgarian Sector of the Danube River—Results of the Joint Danube Survey 4 (JDS4)

The aim of this study was to assess the status of aquatic invasive alien species (IAS) in the shoreline zone of the Bulgarian sector of the Danube River, Danube tributaries, and adjacent standing water bodies in the frame of the Joint Danube Survey 4 (JDS4). Seven benthic macroinvertebrates and seven fish IAS were identified. The crayfish Faxonius limosus was frequently found and abundant in the tributaries. The mussels Corbicula fluminea, Dreissena rostriformis bugensis, and Sinanodonta woodiana dominated in the Danube River and the middle and lower reaches of the tributaries, while the fish Carassius gibelio, Perccottus glenii, and Lepomis gibbosus were most abundant in the standing water bodies. The integrated biocontamination estimated by taxonomic groups (crayfish, molluscs, and fish), sampling methods, and type of water bodies ranged from moderate in the shoreline zone of the Danube River, through moderate to high in the canals and lakes, to severe in the Danube tributaries and the reservoirs. The results demonstrate the importance of IAS in the assessment of the ecological status/potential of the water bodies in the DRB. The comprehensive evaluation of the aquatic IAS pressure will provide valuable information and support for the implementation of the national and EU IAS and water policies in the DRB.

Changes in benthic macro-invertebrate assemblages in an estuary in southern Thailand after invasion by non-native bivalves &lt;i&gt;Mytilopsis sallei&lt;/i&gt; and &lt;i&gt;Mytella strigata&lt;/i&gt;

Mytilopsis sallei (Récluz, 1849), an invasive bivalve, has been established for more than two decades in Pawong Canal, which is a part of the largest lagoon system in Thailand. A recent survey in 2019 revealed the presence in the canal of another invasive species, the mytilid mussel Mytella strigata (Hanley, 1843). Both species are byssally attached bivalves that can change soft bottoms into hard substrata composed of bivalve shells, with consequent effects on benthic communities. Data of benthic macro-invertebrate species collected 25 years ago, before the arrival of both invasive species, were compared with data from a recent survey. Although 28 different species were observed in each study, only five were present in both. However, there is no significant change in the diversity and evenness of this benthic community. A few species of hard-bottom dwellers appeared in the canal after invasion while some soft-sediment inhabitants were absent. Given that the full dataset from the previous study was not available and a long-term series of observations was not made, it is difficult to distinguish the effects of bivalve invasion from the effects of physical change in the environment. However, we documented the current condition of this complex estuarine ecosystem and discussed some possible effects of non-native bivalve invasion on the local benthic macroinvertebrate assemblages.

Ultra-conserved elements provide insights to the biogeographic patterns of three benthic macroinvertebrate species in the Baltic Sea

The Baltic Sea, with its steep salinity gradient, high water retention time, and relatively young age, represents a marginal ecosystem between marine and freshwater extremes. Due to differing invasion history and dispersal capabilities of Baltic species, there are large differences in species distributions, species-specific genetic structure and variation, and edge populations that may represent both a subset of the original population, as well as unique genetic lineages. We used a phylogenomic approach to investigate relationships between populations of three benthic macroinvertebrate species: Pygospio elegans, Corophium volutator, and Mya arenaria, providing new insight into evolutionary dynamics among populations in the Baltic Sea and the adjacent North Sea. We found little relation among the populations of P. elegans and C. volutator, in contrast to M. arenaria, which exhibits a higher degree of resemblance between populations. We also found low relation within sites sampled at different times of the year for all species. Each species exhibited unique phylogenetic patterns, suggesting the North Sea populations of P. elegans and M. arenaria are closely related to populations within the Baltic Sea, and with only C. volutator showing trends resembling isolation by distance. These differences could be explained by both their different invasion histories and dispersal capabilities of the individual species.

The Impacts of the Freezing–Thawing Process on Benthic Macroinvertebrate Communities in Riffles and Pools: A Case Study of China’s Glacier-Fed Stream

Glacier-fed streams are one of the environments most sensitive to global climate change. However, the effects of the freezing–thawing process on benthic macroinvertebrate communities in different habitats of glacier-fed streams are unclear. In this paper, we investigated benthic macroinvertebrates in riffles and pools of a glacier-fed stream in Xinjiang, China, during the pre-freezing period (November, 2018), freezing period (January 2019), and thawing period (April, 2019). Our results showed that the freezing–thawing process resulted in a decline in benthic macroinvertebrate species richness and diversity, both of which were attributed to the effects of the freezing–thawing process on habitat stability, water quality, and cycling of the stream ecosystems. During the whole freezing–thawing process, the indicator taxa of riffles were Rhithrogena sp. and Baetis sp., while the only indicator taxon of pools was Chironomus sp. The species richness, Margalef diversity, and EPT richness (Ephemeroptera, Plecoptera, and Trichoptera) of benthic macroinvertebrates in riffles were higher than those in pools, due to the higher habitat heterogeneity in the riffles. However, the density in riffles was significantly lower than that in pools during the freezing period (p &lt; 0.05). Additionally, pools were dominated by taxa with higher resilience and resistance traits, such as “bi- or multi-voltine”, “abundant occurrence in drift”, and “small size at maturity”. This result indicated that pools provide a temporary refuge for benthic macroinvertebrates in the extreme environment of glacier-fed streams. The freezing–thawing process plays an essential role in the formation of the structure and function of the stream ecosystem. Our results can help us to further understand the winter ecological process of headwater streams, and provide a reference for stream biodiversity conservation in cold regions.

河北唐山曹妃甸-乐亭海域自然牡蛎礁分布及生态意义

牡蛎礁是生态系统服务价值最高的海洋生境之一，目前我国自然牡蛎礁分布和生态现状的基础信息仍然较缺乏。于2019年3月对河北唐山曹妃甸-乐亭海域自然牡蛎礁的空间分布、生态环境、牡蛎生物学和礁体动物群落开展了调查，并评估了该牡蛎礁的生态系统服务价值。该海域自然牡蛎礁分布于溯河（SR）、溯河口海域（SRE）和捞鱼尖海域（LYJ），总面积约15 km²，是目前我国面积最大的自然牡蛎礁。基于96个牡蛎样品的16S rDNA检测，共识别出92个长牡蛎Crassostrea gigas、3个侏儒牡蛎Nanostrea fluctigera和1个巨蛎属未知种Crassostrea sp.。自然牡蛎礁中牡蛎平均密度介于104-3912个/m²之间，不同礁区间牡蛎平均密度的大小排序为：SRE > SR > LYJ （P<0.05），平均生物量的大小排序为：SR > SRE > LYJ （P<0.05），平均壳高的大小排序为：SR > SRE=LYJ （P<0.05）。在该牡蛎礁内记录到49种礁体动物，其中软体动物16种、节肢动物16种、环节动物8种、棘皮动物5种、腔肠动物2种、星形动物和脊索动物各1种；礁体动物群落平均总密度介于28-552个/m²之间，不同礁区间大小排序为：SRE > SR > LYJ （P<0.05）。牡蛎密度与礁体动物群落总密度和总生物量之间呈显著正相关（P<0.05）。该自然牡蛎礁如未受破坏，则其生态系统服务价值高达6.90×10⁸元/年。该牡蛎礁是继海草场后在该海域发现的又一重要的温带海洋生境，是我国自然牡蛎礁地理分布的重大发现。建议加强该自然牡蛎礁的保护与修复，建设一个以牡蛎礁和海草场为核心的资源养护型国家级海洋牧场示范区。;Oyster reef is an important marine habitat that provides a variety of ecosystem services, including water filtration, nitrogen removal, carbon sink, habitat provision and erosion control. In the past decades, most of natural oyster reefs in the Chinese coasts were lost due to overfishing, pollution, sedimentation and habitat destruction. To date, little information was available on spatial distribution and ecological status of natural oyster reefs in China. This study investigated the spatial distribution, ecological environment, oysters and reef-associated resident benthic macroinvertebrate communities at the natural oyster reefs on the coast of Caofeidian-Leting, Tangshan, Hebei Province, and furthermore assessed the ecosystem service values of the natural oyster reefs on the coast. The natural oyster reefs, including three major distribution zones, namely Shouhe River (SR), Shouhe River estuary (SRE) and Laoyujian (LYJ), occupied the total area of about 15 km². To our knowledge it was recognized as the largest natural live oyster reefs in China. Ninety-two of 96 oyster specimens collected from the natural reefs were identified as pacific oyster Crassostrea gigas, 3 specimens for Nanostrea fluctigera and 1 specimen for unknown Crassostrea sp based on 16S rDNA gene sequence analysis. The mean live oyster densities ranged from 104 to 3912 ind./m² at the natural oyster reefs. The mean oyster metrics were ranked as follows (P<0.05):SRE > SR > LYJ for oyster densities, SR > SRE > LYJ for oyster biomass and SR > SRE=LYJ for oyster size (shell height). A total of 49 resident benthic macroinvertebrate species, belonging to 16 mollusks, 16 arthoropoda, 8 annelids, 5 echinodermata, 2 coelenterata, 1 sipuncula and 1 chordata, were recorded at the natural oyster reefs. The mean total densities of resident benthic macroinvertebrate communities varied between 28 and 552 ind./m² at the natural oyster reefs, with ranking as follows:SRE > SR > LYJ (P<0.05). The total densities and biomass of resident macroinvertebrate communities had significantly positive correlations with the oyster densities at the natural oyster reefs. The economic value of the full suite of ecosystem services derived from the natural oyster reefs was recently estimated to be as high as RMB 6.90×10⁸RMB/a. The discovery of the natural live oyster reefs contributed significantly to valuable information on the spatial distribution and ecological status of temperate coastal habitats in China. It was suggested that a national marine ranching demonstration zone should be built on the coast through the conservation and restoration of oyster reefs and seagrass beds.

COMPARATIVE DATA ON MACROZOOBENTHOS COMMUNITY BETWEEN EASTERN AND WESTERN COASTS OF SAZANI ISLAND, ALBANIA

This paper is focused on analysing the difference in distribution, composition and abundance of benthic invertebrates' populations of the rocky coast of Sazan Island (south western Albania), between its eastern and western sides. This study was carried out during 2012-2014, sampling in shallow water. A total of 56 species of benthic macroinvertebrates were recorded. Species composition and their abundance were compared between the four sampling sites and between the two sampling seasons, spring and autumn. Degree of coast exposure and level of environmental impacts seem to be the main factors regarding the difference in species composition and quantitative characteristics of macrozoobenthic community between the eastern and western coasts of the island.

Effects of Water Quality on Spatio-Temporal Diversity of Benthic Macro-Invertebrate Species along the Selected Shores of Lake Victoria, Homa-Bay County, Kenya

Human-induced landscape alterations impact the ecological integrity of water resources by adversely affecting fresh water ecosystems, water-quality, habitat structure, flow regime, and biotic interactions. For instance fresh-water Lake Victoria continues to be affected by massive discharge of waste-waters and other pollutants from the surrounding basin which interfere with the ecological balance leading to adverse impact on benthic macro-invertebrates especially along the lake shores. The objective of this study was to investigate the effect of water quality on the diversity of benthic macro-invertebrates along the shores of Lake Victoria in Homa-Bay County, Kenya. Samples were taken at various beaches including Oluch Kimira River Mouth, Homa Bay Sewage discharge point and Mbita East of course way shoreline and examined for water quality parameters and the species diversity of benthic macro-invertebrates at monthly intervals between September 2019 and Feb 2020. The study was conducted during dry and wet seasons to help determine any changes in waste water discharges, water quality and benthic macro-invertebrates’ characteristics. The results showed significant differences between various sites along the 3 different sites. During both wet and dry periods, Oluch Kimira and Homa Bay recorded low DO levels (4.0±0.46 to 6.2±0.19) MgL-1, while Mbita East of the course way throughout the period recorded DO level of (5.6±0.23 to 7.7±0.17) MgL-1. The mean concentration of Ammonia,NH4(µgL¯¹) during the dry season was (6.32 ±.3.55 to 8.79±3.02) and during the wet season 12.16± 0.92 to 22.50 ± 0.52. The county government should implement the findings of this study, which provides baseline data for evaluating the trends in water quality and related changes in benthic-macro invertebrates biodiversity in Lake Victoria shorelines in Homa Bay County. The findings will also help in making policy decisions in order to support environmental protection in Lake Victoria.

Development of benthic macroinvertebrate species distribution models using the Bayesian optimization

Development of benthic macroinvertebrate species distribution models using the Bayesian optimization