Determination of the Fish Community Structure of an Intertidal Rocky Zone of the Pacific Coast of Baja California Sur

The intertidal zone (also known as seashore) are transition areas between land and sea, that are greatly influenced by the tide cycle, therefore, environmental parameters, such as temperature and salinity, oscillate according to the periods in which these areas are exposed to air. Intertidal zones are highly diverse, which makes them key ecosystems for the development of sea life (both flora and fauna) exposed to drastic environmental change. The 59 visual censuses campaigns were carried out during the full moon of each month from 2015 to 2019. Temperature, salinity and dissolved oxygen were recorded during each visual census and showed variations between years. Temperature showed two distinct seasons, warm and cold. A total of 14,995 organisms were recorded, belonging to 30 species, 28 genera, 15 families, five orders and one class. Ecological indices like species richness (SR), Shannon-Wiener’s diversity (H') and Fisher’s alpha (α-Fisher) showed significant differences between years, 2015 and 2016 recorded as the most diverse years, while the lowest values were recorded in 2019. Therefore, fish communities of tide pools showed to be highly diverse, with 30 species recording similar relative abundances, and according to the BVI, only 11 species were dominant. Spatio-temporal variations of temperature, salinity and dissolved oxygen were highly correlated to changes in fish community structure, and the dominance of certain species, which are of great importance for the structure and dynamic of the tide pool communities. Therefore, the aim of the present study was to determine the fish community structure of tide pools during the low tide in the intertidal zone of a locality known as El Faro, on the west coast of La Paz, B. C. S., Mexico.

Study on fish community structure in the Zhujiang Estuaryand its adjacent waters

Based on data of demersal trawl Samples from 1987 to 1988 in the Zhujiang Estuary and its adjacent waters, relationships between fish community and environmental factors are studied by using clssification , MDS ordina-tion and several community parameters. The results shaw that the distribution of fish shoes is zoned by salinty anddivided into three types. The freshwater community which is restricted in the Lianhua Hill - Humen waterway is sim-ple and stable, the coastal community which lives in the shallow waters is complex, and the estuary community whichis idenhfied in the Lingdingyang area and affected by Physical and ecological pinemore greatly greatly has obvious seasonalvariations.

Functional Diversity of the Fish Community Associated to Soft-Bottoms in the Lagoon of La Paz B.C.S., México

There has been an increase of community studies that incorporate the use of functional diversity indices. The incorporation of these indices in the analysis of marine communities is recent, however, could contribute with relevant information about the health of those communities. The lagoon of La Paz is a body of water located in La Paz, B.C.S., México. Despite its regional importance, there are not recent studies about its fish communities. Therefore, the aim of the present study was to analyze the temporal and spatial structure of the functional diversity of fish communities associated to soft bottoms, from August 2016 to July 2017, as well as important environmental variables. Functional diversity indices showed significant differences between months. Spatial analysis did not show significant differences perhaps due to low variability of the type of substrate. Temperature showed temporal differences as well. Therefore, temperature may be a limiting environmental variable for many fish species inhabiting coastal lagoons.

Assessment of the Characteristics of Demersal Fish Communities Using Species-and Trait-Based Approaches in the Coastal Habitats Along Rongcheng Bay,Shandong Peninsula,China

Biodiversity declines have motivated many studies on the relationship between species diversity and ecosystem functioning.In this study,we described the spatial-temporal characteristics of demersal fish communities along a coastal habitat in Rongcheng Bay,Shandong Peninsula,China with both species-based and biological trait-based approaches.The field survey was carried out monthly using traps from April to October of 2018,and divided into three seasons(spring:April and May;summer:June,July and August;autumn:September,October and November).The study area included five distinct habitats:seagrass bed,natural rocky reef,bare sand,artificial reef together with natural rocky reef,and artificial reef together with bare sand.We analyzed the fish communities with three taxonomic diversity indices,including Shannon-Wiener,Simpson,and Pielou Evenness,as well as four functional diversity indices,including FRic,FEve,FDiv,and FDis,based on 7 functional groups which are categorized into 27 traits.The results showed that there were no significant differences in taxonomic diversity indices among different habitats in the three seasons.However,significant differences were found in the functional richness of fish communities among different habitats in three seasons.Seagrass bed represented the highest functional richness in spring and autumn.This study demonstrates that seagrass bed is very important in enhancing the functional diversity of fish communities in a complex habitat.The study also indicates that the combination of taxonomic diversity and functional diversity will provide a more detailed description of the characteristics of fish communities.

Quantifying relations between altered hydrology and fish community responses for streams in Minnesota

Background:Altered hydrology is a stressor on aquatic life,but quantitative relations between specific aspects of streamflow alteration and biological responses have not been developed on a statewide scale in Minnesota.Best sub-sets regression analysis was used to develop linear regression models that quantify relations among five categories of hydrologic metrics(i.e.,duration,frequency,magnitude,rate-of-change,and timing)computed from streamgage records and six categories of biological metrics(i.e.,composition,habitat,life history,reproductive,tolerance,trophic)computed from fish-community samples,as well as fish-based indices of biotic integrity(FIBI)scores and FIBI scores normalized to an impairment threshold of the corresponding stream class(FIBI_BCG4).Relations between hydrology and fish community responses were examined using three hydrologic datasets that represented periods of record,long-term changes,and short-term changes to flow regimes in streams of Minnesota.Results:Regression models demonstrated significant relations between hydrologic explanatory metrics and fish-based biological response metrics,and the five regression models with the strongest linear relations explained over 70%of the variability in the biological metric using three hydrologic metrics as explanatory variables.Tolerance-based biological metrics demonstrated the strongest linear relations to hydrologic metrics.The most commonly used hydrologic metrics were related to bankfull flows and aspects of flow variability.Conclusions:Final regression models represent paired streamgage records and biological samples throughout the State of Minnesota and encompass differences in stream orders,hydrologic landscape units,and watershed sizes.Presented methods can support evaluations of stream fish communities and facilitate targeted efforts to improve the health of fish communities.Methods also can be applied to locations outside of Minnesota with continuous streamgage data and fish-community samples.

Comparative fish community structure among different types of enclosures of estuarine environments

This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary(MRE),Geum River Estuary(GRE),and Han River Esturay(HRE)with similar ranges of seasonal water temperature that are diked with different levels of disconnection from freshwater discharge.The distribution of major species in the three estuaries could generally be grouped into three distinctive patterns based on their cumulative distribution with respect to the salinity gradient.The MRE was geographically closer to the GRE than to the HRE,but the fish community of the MRE more closely resembled that of the HRE.Increased freshness of the water inside the dike and the limit of coastal fish to the river may have led to this result.The results provide clues to how enclosure patterns of estuarine waters could affect fish communities over a long-term period.In addition,the information may provide guidance for how a fish community may return once environmental conditions are restored.

Influence of sampling frequency on detectability of fish community and fish species in a fishery-independent survey

Understanding the dynamics and regulation of a particular ecological process requires monitoring of the process at appropriate spatial and temporal scales.Information collected at an inappropriate spatiotemporal scale may be insufficient for capturing spatio-temporal dynamics of fish populations and community.In this study,a Monte Carlo method was developed to evaluate the detectability performances of different sampling frequencies,sampling timings and sampling intensities on fish community indices and fish species.Species richness indices tended to decrease with an increased sampling frequency,while species diversity indices had small changes in response to changes in sampling frequency.The diversity index was more likely to be influenced by the choice of sampling timing compared to the richness index.The total number of species,especially seasonal and rare species present in the simulated sampling,increased with sampling frequency.Although sampling frequency is more important than sampling intensity,sampling intensity is also important for the detectability of fish species.This study showed that sampling frequency and intensity could greatly influence the estimation of fish community.Choices of sampling timing,sampling frequency and intensity may result in different estimates of fish species compositions and community structure.It is very necessary to consider the importance of sufficient sampling frequency and intensity in a survey program.

Angling of hybrid sunfish from a hatchery pond with potential implications for community fisheries

Hatcheries are frequently called upon to produce catchable-sized fish for stocking community fishing ponds.Desirable attributes of fish selected for stocking into community ponds are that they are easy to produce in a hatchery system to sizes anglers are interested in catching and they provide anglers with high catch rates once stocked.Hybrid sunfish[male Bluegill(Lepomis macrochirus)×female Green Sunfish(L.cyanellus)]have attributes that potentially make them attractive for use in community fishing ponds.We assessed initial angler catch rates of 100 stocked hybrid sunfish in a 0.12-ha hatchery pond and after being subjected to angling(four,1-hr catch-and-release fishing events with five anglers).We also investigated whether catch rates would change following a supplemental stocking of an additional 100 hybrid sunfish(four,1-hr catch-and-release fishing events with five anglers).The anal fin of each fish in the second stocking was hole punched to differentiate them from those of the first stocking and fish caught by anglers were hole punched in the caudal fin each time they were caught before being released back into the pond.Angler catch rates were highest during initial fishing events that followed stocking(9.2 fish/angler hr and 18.0 fish/angler hr)and substantially declined in subsequent events(≤3.4 fish/angler hr).Catches of the newly stocked fish and previously stocked fish contributed to the high catch following the supplemental stocking.Most(80%)of the fish were caught in the first 30 min of each event and 45%were caught during the first 10 min.Anglers were able to catch 88%of the fish from the first stocking and 67%from the second stocking at least once.No mortality occurred during the study as all fish were recovered when the pond was drained.Our results suggest that hybrid sunfish will potentially provide high initial catch rates following stocking into community ponds,but managers should expect reduced catch rates following initial fishing even without harvest.Additional stocking will be needed to provide periodic increases in angler catch rates even without harvest.

Evaluation of cone fishways to facilitate passage of small-bodied fish

Fishways are being provided more regularly than ever before and new designs are needed to provide passage for whole fish communities.Despite recent progress,fishways have frequently performed poorly,especially for small-bodied fish(i.e.10-100 mm long),which can form large aggregations below stream barriers.This was the genesis for the development of the cone fishway design,a new style of technical fishway which consists of a series of pre-fabricated cone-shaped concrete baffles installed laterally within a concrete channel.The cone design arose from the need to install rock ramp fishways at remote sites where rock was unavailable and where maintenance would be infrequent.The objective of the present study was to evaluate the suitability of the new cone fishway design to provide passage for small-bodied diadromous species(i.e.<100 mm long).Cone fishways were evaluated at three low head(e.g.<3 m high)case-study sites in tropical and temperate Australia and in total,45 species and 28,556 fish were collected.There was passage of a broad range of the target size-classes of small-bodied fish and individuals as small as nine mm could ascend.However,further work is needed to quantify the proportion of the small-bodied fish population in the river downstream which find and pass through the cone fishways.The most suitable experimental application of the cone fishway is at sites where there is:(i)a narrow(e.g.<0.4 m)headwater range,and(ii)where passage of small-bodied fish is a major ecological priority.Cone fishways provide a useful and novel option to improve passage of small-bodied fish,at appropriate sites,and contribute to a contemporary vision of restoration of whole fish communities.

Impact of anthropogenic activities on changes of ichthyofauna in the middle and lower Xiang River

With the population increasing,fish communities,as important components in the river system,were inescapably impacted by human activities.To investigate these impacts,we characterized the fish community’s composition by environmental DNA metabarcoding in the urban and suburban sites along Xiang River in central China.The results showed that 32 species were identified,and most species were from Cypriniform.The analysis indicated no significant differences in fish communities among the three urban areas.However,significant differences were observed between the bank solidified and non-solidified areas,which indicated that the channelization significantly influenced the biodiversity and abundances.An alien species,Clarias gariepinus,was discovered in all examined sites,and it was negatively associated with ten native species.Furthermore,human populations and acidification were also negatively related to diversity.Our findings clearly showed that the consequences of anthropogenic activities shaped ichthyofauna and caused biodiversity loss in the urban river.