Community structure of benthic invertebrates in the Allipén River basin, North Patagonia, Araucania region (38º S, Chile)

One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H’≤ 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.

Lagoon ecosystems: peculiarities of the species, spatial and trophic structure of macrobenthos (Kandalaksha bay, White sea)

Изучены видовое разнообразие, пространственная и трофическая структура макробентосных сообществ сублиторали и нижних горизонтов литорали в 5-ти лагунных экосистемах Кандалакшского залива Белого моря. Всего в исследованных экосистемах было обнаружено 52 вида бентосных беспозвоночных животных и 6 видов морских трав и водорослей. В сублиторали наибольшим видовым разнообразием, общей плотностью и биомассой макробентоса характеризуется наиболее открытая к морю лагуна, расположенная на выходе из кутовой области Кислой губы, а наименьшим - наиболее закрытая и заиленная лагуна Никольской губы, где преобладали солоноватоводные и морские эвригалинные виды. Промежуточное положение занимали лагуна Ермолинской губы, лагуна, расположенная рядом с Ершовским озером и лагуна на Зеленом мысу. В нижней литорали общие показатели структуры сообщества макробентоса (общая плотность, биомасса и в меньшей степени видовое разнообразие) в отличие от сублиторали увеличивались от менее зарегулированных и открытых экосистем к более закрытым системам. Исключением является лагуна Никольской губы, значительное заиление которой приводит к существенному уменьшению видового разнообразия и снижению общей плотности и биомассы сообщества макробентоса. The species diversity, spatial and trophic structure of macrobenthos communities in the sublittoral and lower littoral horizons in five lagoon ecosystems of the Kandalaksha Bay of the White Sea have been studied. In total, 52 species of benthic invertebrates and 6 species of sea grasses and algae were found in the studied ecosystems. In the sublittoral zone, the highest species diversity, total density and biomass of macrobenthos is characterized by the lagoon most open to the sea, located at the exit from the innermost area of Kislaya Bay. The lowest diversity is found in the most closed and silted lagoon of Nikolskaya Bay, where brackish water and marine euryhaline species predominated. The lagoon of the Ermolinskaya Bay, the lagoon located next to the Ershov Lake and the lagoon on Cape Verde hold an intermediate position. In the lower littoral zone, the general indicators of the structure of the macrobenthos community (total density, biomass, and, to a lesser extent, species diversity), in contrast to the sublittoral one, increased from less regulated and open ecosystems to more closed systems. An exception is the lagoon of Nikolskaya Bay, the significant siltation of which leads to a significant decrease in species diversity and a decrease in the total density and biomass of the macrobenthos community.

Behavioural Stress Propagation in Benthic Invertebrates Caused by Acute pH Drop-Induced Metabolites

Studies on pH stress in marine animals typically focus on direct or species-specific aspects. We here test the hypothesis that a drop to pH = 7.6 indirectly affects the intra- and interspecific interactions of benthic invertebrates by means of chemical communication. We recorded fitness-relevant behaviours of small hermit crabs Diogenes pugilator, green shore crabs Carcinus maenas, and harbour ragworms Hediste diversicolor in response to short-term pH drop, and to putative stress metabolites released by conspecifics or gilt-head sea bream Sparus aurata during 30 min of acute pH drop. Not only did acute pH drop itself impair time to find a food cue in small hermit crabs and burrowing in harbour ragworms, but similar effects were observed under exposure to pH drop-induced stress metabolites. Stress metabolites from S. aurata, but not its regular control metabolites, also induced avoidance responses in all recipient species. Here, we confirm that a short-term abrupt pH drop, an abiotic stressor, has the capacity to trigger the release of metabolites which induce behavioural responses in conspecific and heterospecific individuals, which can be interpreted as a behavioural cost. Our findings that stress responses can be indirectly propagated through means of chemical communication warrant further research to confirm the effect size of the behavioural impairments caused by stress metabolites and to characterise their chemical nature.

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.

Field evidence for microplastic interactions in marine benthic invertebrates

Microplastics represent an important issue of concern for marine ecosystems worldwide, and closed seas, such as the Mediterranean, are among the most affected by this increasing threat. These pollutants accumulate in large quantities in benthic environments causing detrimental effects on diverse biocenoses. The main focus of this study is on the ‘polychaetes-microplastics’ interactions, particularly on two species of benthic polychaetes with different ecology and feeding strategies: the sessile and filter feeder Sabella spallanzanii (Gmelin, 1791) and the vagile carnivorous Hermodice carunculata (Pallas, 1766). Since not standardized protocols are proposed in literature to date, we compared efficiencies of diverse common procedures suitable for digesting organic matter of polychaetes. After the definition of an efficient digestion protocol for microplastics extraction for both polychaetes, our results showed high microplastics ingestion in both species. Microplastics were found in 42% of individuals of S. spallanzanii, with a mean of 1 (± 1.62) microplastics per individual, in almost all individuals of H. carunculata (93%), with a mean of 3.35 (± 2.60). These significant differences emerged between S. spallanzanii and H. carunculata, is probably due to the diverse feeding strategies. The susceptibility to this pollutant makes these species good bioindicators of the impact of microplastics on biota.

Lobster Distribution and Biodiversity on the Continental Shelf of Brazil: A Review

The continental shelf of Brazil is home to a wide range of lobster species, with varying body size, color, habitat preference, and geographic and bathymetric distribution. Spiny lobsters (Panulirus) and slipper lobsters (Scyllaridae) are exploited for export and for the domestic market. Deep sea lobsters (Nephropidae and Polychelidae) have no commercial potential, and little is known about their biology. In this review, we identified 24 lobster species from benthic ecosystems off Brazil (Palinuridae 25%, Scyllaridae 29%, Nephropidae 25%, Polychelidae 17%, Enoplometopidae 4%). We designed a simplified theoretical scheme to understand the role of lobsters in the ecosystem, based on available evidence of distribution, biodiversity, life cycle, connectivity, and abundance. Finally, we propose a theoretical scheme of trophic top-down control, with interactions between a large decapod (spiny lobster), a demersal predator (red snapper), an apex predator (small tuna), benthic invertebrates and fishing exploitation.

Recovery of freshwater invertebrates in alpine lakes and streams following eradication of nonnative trout with rotenone

Nonnative fish eradication via the piscicide rotenone is an effective tool for fisheries management and conservation of native species. However, the long-term effects on non-target organisms, including benthic invertebrates and zooplankton in alpine lakes, are under-studied and are poorly understood. As part of a landscape-scale native fish conservation project, we assessed the effects of 50 ppb rotenone on the aquatic invertebrate community by comparing pre- and post-rotenone treatment density and diversity metrics of benthic invertebrates and zooplankton in 13 alpine lakes and their outlets in Montana, USA. Across study sites, decreases in density and diversity of some invertebrates, including Ephemeroptera, Plecoptera, and Trichoptera taxa, were observed the year following rotenone treatment, and within three years, densities and diversities were similar to and sometimes higher than pre-treatment values. These results demonstrate resilience of aquatic invertebrate communities following rotenone exposure in alpine lakes and streams and informs fisheries managers for planning rotenone projects and monitoring recovery of non-target organisms. Further studies will be useful to evaluate the mechanisms driving invertebrate recovery rates, including downstream drift from nontreated areas and terrestrial adult dispersal.