scholarly journals Space-time variations of megazoobenthos subject to natural and anthropogenic impacts in two Cuban bays: evidence of recovery?

2021 ◽  
Vol 49 (1) ◽  
pp. 97-109
Author(s):  
Alexander Lopeztegui-Castillo ◽  
Norberto Capetillo-Piñar ◽  
Abel Betanzos-Vega ◽  
Beatriz Martínez-Daranas ◽  
Diana Martínez-Coello ◽  
...  
Keyword(s):  
Anthropogenic Impacts ◽  
Benthic Fauna ◽  
Progressive Increase ◽  
Bottom Trawl ◽  
Total Biomass ◽  
Total Density ◽  
Buena Vista ◽  
Soft Bottoms ◽  
Density And Biomass ◽  
Trawl Fisheries

The spatiotemporal variations of megazoobenthos on soft bottoms in Buena Vista (BV) and San Juan de Los Remedios (SJR) bays, Cuba, were assessed to infer the effects of the elimination of bottom trawl fisheries and the creation of protected areas. Data were collected at 11 sites in 2010-2013 (six routines and five exploratories) and 11 sites in 2014-2017 (four routines and seven exploratories). Samples were obtained by dredging. Mollusks were the most frequent and diverse group, followed by echinoderms and crustaceans. Total density (7.60 ind m-2) and biomass (15.82 g m-2) of the benthic community were highest in SJR in 2015. Although total biomass was lower at BV (t = 2.21; P = 0.032), there were no significant differences in density between bays (t = 0.77; P = 0.444). The site with a lower total density and biomass was located at BV. There were no differences between years except at one site, where density increased between 2010 and 2017. Total density and biomass were not significantly different inside and outside of the Zone Under Special Regime of Use and Protection (ZUSRUP) at the beginning of the sampled period. However, both density and biomass were significantly higher within the ZUSRUP at the end (2017), which suggests this protected area’s effectivity. The progressive increase in density at one site and greater density and biomass values at SJR, where bottom trawl fisheries were more intensive, suggest eliminating bottom trawl nets may have contributed to the benthic fauna recovery.

scholarly journals A Mega-Nourishment (Sand Motor) Affects Landscape Diversity of Subtidal Benthic Fauna

2021 ◽  
Vol 8 ◽  
Author(s):  
Peter M. J. Herman ◽  
J. J. Simeon Moons ◽  
Jeroen W. M. Wijsman ◽  
Arjen P. Luijendijk ◽  
Tom Ysebaert
Keyword(s):  
Benthic Fauna ◽  
Physical Factors ◽  
Total Biomass ◽  
Total Density ◽  
Species Accumulation Curves ◽  
Environmental Evaluation ◽  
Number Of Species ◽  
Before And After ◽  
Long Time ◽  
Waves And Currents

The Sand Motor is a very large (20 million m3) nourishment constructed along the coast in The Netherlands. The huge volume of sand is redistributed along the coast by natural forces stemming from tidal currents and waves. For environmental evaluation of this large construction, the benthic subtidal fauna has been sampled prior to the construction of the Sand Motor, and at 1, 2, 4, and 6 years after construction. Although some significant differences between years were detected, overall the total density, total biomass and average number of species per sample were surprisingly constant over this time period. However, large differences were found in the species accumulation curves over samples, and in the rank-biomass and rank-abundance plots. These were related to two important trends in the communities. First, the invasive mollusk Ensis leei, the biomass dominant in the years before construction of the Sand Motor, dwindled in importance in later years. Recruitment of the species failed, but it is unclear whether, and how, this is related to the construction of the Sand Motor. Second, the correlation structure between depth, grain size, bottom shear stress due to waves and currents, which is very tight along a linear coast, was disrupted by the Sand Motor. The community composition was shown to depend strongly on these physical factors. The nature of the dependencies did not change, but the range of different combinations of factors after construction of the Sand Motor was widely larger than before. Although samples had similar number of species per sample before and after construction, the average difference between samples after construction was much larger than before. The Sand Motor is a very large construction, leading to loss of a substantial area (order 100 ha) of submarine area, which recovers at a long time scale. Total disturbance of benthos by burial, expressed as area∗(time before full recovery) was shown to be similar for the Sand Motor and for other coastal nourishment schemes when expressed per unit volume of sediment applied. However, in contrast to beach and shoreface nourishments, the Sand Motor led to a habitat diversification in the coastal zone.

scholarly journals Density and Biomass of Seagrass Beds and Its Threats on Lamongan Regency

2020 ◽  
Vol 7 (3) ◽  
pp. 186-191
Author(s):  
Citra Satrya Utama Dewi ◽  
Defri Yona ◽  
Pratama Diffi Samuel ◽  
Rizqi Aimmatul Maulidiyah ◽  
Ahdiya Syahrir ◽  
...  
Keyword(s):  
Total Biomass ◽  
Total Density ◽  
Seagrass Beds ◽  
Seagrass Species ◽  
Sample Processing ◽  
Tourism Sector ◽  
Seagrass Biomass ◽  
Density Values ◽  
Density And Biomass ◽  
Seagrass Density

This study aimed to determine the density of seagrass species, seagrass biomass, and threats faced by seagrass communities in the Coastal District of Lamongan. The study was conducted from August to November 2019 in three coastal villages of Lamongan Regency, namely Tunggul Village (Station 1), Kranji Village (Station 2), and Banjarwati Village (Station 3). Furthermore, the stages of the study consisted of preparation, data collection on density, threat data, seagrass stand samples, sample processing, and data analysis. The results showed that the total density of seagrass species at Stations 1, 2, and 3 was 160 stands/m2, 172 stands/m2, and 185 stands/m2, respectively. Moreover, the total biomass of seagrass at Stations 1, 2, and 3 was 4633 g/m2, 2136 g/m2, and 9234 g/m2, respectively. In addition to seagrass species, seagrass density values also affected seagrass biomass. As development progresses in Lamongan Regency, it is known that the biggest threat of seagrass communities in the study site is human activity (anthropogenic), especially the anchor ships when anchored and the use of coastal areas as tourist areas. This occasion often cleans up seagrass communities because they are deemed unfit to be enjoyed tourism sector.

scholarly journals Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

2013 ◽  
Vol 103 (4) ◽  
pp. 342-349 ◽  
Author(s):  
Leticia M. Mesa ◽  
María Celina Reynaga ◽  
Marcela del V. Correa ◽  
Martín G. Sirombra
Keyword(s):  
Environmental Changes ◽  
Functional Organization ◽  
Anthropogenic Impacts ◽  
Anthropogenic Activities ◽  
Benthic Fauna ◽  
Total Density ◽  
Functional Feeding Group ◽  
Macroinvertebrate Assemblages ◽  
Feeding Group ◽  
Surrounding Landscape

The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

scholarly journals Geoenvironmental Implications and Biocenosis of Freshwater Lakes in the Arid Zone of East Kazakhstan

2021 ◽  
Vol 13 (10) ◽  
pp. 5756
Author(s):  
Talant N. Samarkhanov ◽  
Anar B. Myrzagaliyeva ◽  
Jiri Chlachula ◽  
Ludmila B. Kushnikova ◽  
Jolanta Czerniawska ◽  
...  
Keyword(s):  
Central Asia ◽  
Arid Zone ◽  
Anthropogenic Impacts ◽  
Benthic Fauna ◽  
Steppe Zone ◽  
Taxonomic Composition ◽  
Nature Protection ◽  
Aquatic Biomass ◽  
East Kazakhstan ◽  
Lacustrine Basins

Steppe and semi-desert lakes of Central Asia represent unique and still poorly known aquatic ecosystems. The paper provides summaries of multi-proxy environmental and biological investigations of the previously unexplored ground of Sibe lakes in the naturally pristine zone of East Kazakhstan, and of their contributions to people. Data on the taxonomic composition of zooplankton and zoobenthos of these freshwater lacustrine basins are presented in terms of the species’ frequency of occurrence; the abundance of the aquatic biomass and the analyzed water geochemical variables insofar as they are dependent and correlative. The qualitative and quantitative records display variability in the biocenosis diversity due to the lakes’ geochemistry and hydrology differences—some lakes being oligotrophic and others being moderately trophic. In the latter case, the lakes characterized by an increased macrozoobenthos biomass are favourable for local ichthyofauna. Sapro-biological analysis reveals the predominance of β-saprobic species in the zooplankton composition pointing to slight or moderate pollution of surface waters due to natural biotic substances. This observation is in agreement with differences in the water quality of solitary lakes. The uneven distributions of benthic invertebrates (in terms of taxonomy and species populations) in the water bodies suggest specific hydro-ecological conditions that predetermine the structure of the lakes’ biocenosis. The littoral part of the lakes is characterized by the highest abundance of zooplankton and benthic fauna. The Sibe lakes are an example of an autonomous functioning of the lacustrine basins in the upland arid steppe zone, which is characterized by pronounced climate “continentality” and a high level of the sub-aquatic flora and fauna endemism. The present results are relevant to the understanding of the ecosystems’ dynamics and the modern anthropogenic impacts upon the pristine parkland-steppe landscapes of Central Asia, with implications for regional nature protection and sustainable eco-recreation.

The importance of alien species to the food web and bottom trawl fisheries of the Northeastern Mediterranean, a modelling approach

2020 ◽  
Vol 202 ◽  
pp. 103253 ◽  
Author(s):  
İsmet Saygu ◽  
Johanna J. Heymans ◽  
Clive J. Fox ◽  
Hüseyin Özbilgin ◽  
Ahmet Raif Eryaşar ◽  
...  
Keyword(s):  
Food Web ◽  
Alien Species ◽  
Bottom Trawl ◽  
Trawl Fisheries ◽  
Modelling Approach

scholarly journals Ectoparasite extinction in simplified lizard assemblages during experimental island invasion

2020 ◽  
Vol 16 (8) ◽  
pp. 20200474 ◽  
Author(s):  
Christian L. Cox ◽  
Sean Alexander ◽  
Brianna Casement ◽  
Albert K. Chung ◽  
John David Curlis ◽  
...  
Keyword(s):  
Introduced Species ◽  
Native Species ◽  
Population Expansion ◽  
Enemy Release ◽  
Total Density ◽  
Agonistic Interactions ◽  
Native Communities ◽  
Trombiculid Mite ◽  
Density And Biomass ◽  
Field Transplant

Introduced species can become invasive, damaging ecosystems and disrupting economies through explosive population growth. One mechanism underlying population expansion in invasive populations is ‘enemy release’, whereby the invader experiences relaxation of agonistic interactions with other species, including parasites. However, direct observational evidence of release from parasitism during invasion is rare. We mimicked the early stages of invasion by experimentally translocating populations of mite-parasitized slender anole lizards ( Anolis apletophallus ) to islands that varied in the number of native anoles. Two islands were anole-free prior to the introduction, whereas a third island had a resident population of Gaige's anole ( Anolis gaigei ). We then characterized changes in trombiculid mite parasitism over multiple generations post-introduction. We found that mites rapidly went extinct on one-species islands, but that lizards introduced to the two-species island retained mites. After three generations, the two-species island had the highest total density and biomass of lizards, but the lowest density of the introduced species, implying that the ‘invasion’ had been less successful. This field-transplant study suggests that native species can be ‘enemy reservoirs’ that facilitate co-colonization of ectoparasites with the invasive host. Broadly, these results indicate that the presence of intact and diverse native communities may help to curb invasiveness.

Drivers of nano- and microplanktonic community structure in a Patagonian tidal flat ecosystem

2019 ◽  
Vol 41 (5) ◽  
pp. 621-639
Author(s):  
Juan F Saad ◽  
Maite A Narvarte ◽  
Mariza A Abrameto ◽  
Viviana A Alder
Keyword(s):  
Tidal Flat ◽  
Tidal Flats ◽  
Size Spectrum ◽  
Spatial Gradient ◽  
Total Biomass ◽  
Total Density ◽  
Phytoplankton Structure ◽  
Tidal Transport ◽  
Sw Atlantic ◽  
Inshore Waters

ABSTRACT Tidal flats are exceptionally dynamic coastal ecosystems. Tides are their main source of energy, whose influence decreases landwards (as land elevation increases), thus shaping physical, chemical and biological gradients. In this study, we assess whether the structure of nano- and microplankton varies along a spatial gradient in San Antonio Bay (SAB, SW Atlantic), a semi-desert coastal ecosystem with a wide tidal flat and a macrotidal regime. We hypothesize that the tidal effect shapes SAB’s both taxonomical groups and size spectrum. The seasonal sampling of 9 sites revealed that diatoms and small flagellates were the most abundant groups, together accounting for over 75% of total density in practically all sites and seasons. High densities of meroplanktonic stages of Ulva lactuca were recorded in spring at the innermost sites, accounting for over 95% of all planktonic cells. Slopes of the size spectrum analysis were in line with highly productive inshore waters (mean, −0.64) and showed that larger phytoplankton was the main contributor to total biomass, despite its decreasing importance toward inner sites. The spatial and seasonal variations found for lower trophic web compartments provide evidence of the importance of tidal transport in ruling phytoplankton structure in tidal flats under strong macrotidal regimes.

scholarly journals Can a square-mesh panel inserted in front of the cod end improve size and species selectivity in Mediterranean trawl fisheries?

2018 ◽  
Vol 75 (5) ◽  
pp. 704-713 ◽  
Author(s):  
Jure Brčić ◽  
Bent Herrmann ◽  
Antonello Sala
Keyword(s):  
Deep Water ◽  
Bottom Trawl ◽  
Horse Mackerel ◽  
Trachurus Trachurus ◽  
Merluccius Merluccius ◽  
Low Probability ◽  
Low Efficiency ◽  
Trawl Fisheries ◽  
European Hake ◽  
Atlantic Horse Mackerel

An experiment was conducted to assess the selectivity in a typical Mediterranean bottom trawl, equipped with a square-mesh panel inserted in front of the cod end, for Atlantic horse mackerel (Trachurus trachurus), European hake (Merluccius merluccius), red mullet (Mullus barbatus), poor cod (Trisopterus minutus), broadtail shortfin squid (Illex coindetii), and deep-water rose shrimp (Parapaeneus longirostris). The release efficiency of undersized individuals through the panel was low. The differences in selectivity between the gear with and without the panel were very small. The low release efficiency of the square-mesh panel was caused by the lack of fish contact with the panel as they drifted towards the cod end, since the average contact probability was estimated not to exceed 9% for any of the species investigated. A low probability of contact with the selection device was thus found to be the reason for the low efficiency of the square-mesh panel.

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