Hydrobiology

19 pages, 2879 KiB

Open AccessArticle

How Tolerant Are Hydroids to Climate-Change-Induced Acute Spikes in Sea Water Temperature? A Case Study of Arctic Dynamena pumila (L., 1758)

by Nikolay N. Marfenin, Vitaly S. Dementyev and Evgeny V. Nikolaev

Hydrobiology 2023, 2(4), 583-601; https://doi.org/10.3390/hydrobiology2040039 - 13 Nov 2023

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Abstract

The temperature of the water surface layer in the Arctic may increase significantly in the coming decades. To what extent will shallow-water fauna be affected by warming? We investigated this issue using an example of one species of colonial hydroid, Dynamena pumila. We judged its reaction to warming via its pulsation activity and the growth of stolons. Pulsations of the coenosarc in colonial hydroids are a sensitive indicator of the body’s reaction to the influence of environmental factors. We tested the ability of D. pumila colonies to survive and adapt to existing at 25 °C for five days. After raising the temperature from 14 °C to 25 °C, colony growth and the pulsation of stolon growth tips on the first day increased and then decreased during the day. In the following days, the growth pulsations almost ceased, the colonies stopped growing, and their coenosarcs began to exfoliate from their perisarcs. However, by the fourth day, this process slowed down, and the colonies existed in an economy mode of experiencing unfavourable conditions. The thermal shock continued in the experiment for five days. Then, after the temperature dropped from 25 °C to 15–16 °C, all the colonies recovered within five days and continued to grow. Full article

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8 pages, 2270 KiB

Open AccessCommunication

A Rarely Reported Crustacean Species, Rissoides pallidus (Giesbrecht, 1910) (Stomatopoda, Squillidae), Caught in the Strait of Sicily Waters (Central Mediterranean Sea)

by Giacomo Sardo, Michele Luca Geraci, Fabio Falsone, Charles Odilichukwu R. Okpala, Danilo Scannella, Antonino Titone and Sergio Vitale

Hydrobiology 2023, 2(4), 575-582; https://doi.org/10.3390/hydrobiology2040038 - 31 Oct 2023

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Abstract

The mantis shrimp Rissoides pallidus (Giesbrecht, 1910) is a rarely reported crustacean species in the central Mediterranean Sea. In December 2020, during a trawl survey off Mazara del Vallo harbor (Strait of Sicily), two specimens of R. pallidus were captured on coastal detritus and coastal terrigenous mud bottoms at about 132 and 152 m depths. Additional information specific to biometrics, bottom types, depth preference, habitats, and geographic distribution of this crustacean species are provided. Full article

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21 pages, 4609 KiB

Open AccessArticle

Niphargus carolinensis sp. nov. (Amphipoda: Niphargidae), an Endemic Species in the Northern Distribution Area of the Genus

by Dieter Weber and Traian Brad

Hydrobiology 2023, 2(4), 554-574; https://doi.org/10.3390/hydrobiology2040037 - 30 Oct 2023

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Abstract

Niphargus carolinensis sp. nov. was sampled from the Carolina Mine located in North Rhine–Westphalia, Germany. The new species is described and compared to phylogenetically related species and species identified in nearby locations. The three phylogenetic markers (i.e., COI, 28S rRNA and ITS2) studied in the examined specimens had different sequences compared to those belonging to species present in locations neighboring the Carolina Mine, i.e., in a radius of 40 km. N. carolinensis sp. nov. is a small-to-medium-sized species that is poorly setose; has a relatively short antenna I, trapezoidal gnathopod propodites, long pereopod VI, and short uropod III; and is not differentiated sexually. The new species described herein is a case of narrow endemism and adds to the diversity of the genus Niphargus in Germany. This work is a contribution to knowledge on groundwater amphipod diversity and the systematics of the genus Niphargus close to the northern border of the distribution of this genus. Full article

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17 pages, 4518 KiB

Open AccessArticle

Insights into Diatom Substrate Preferences in the Inter-Tidal Zone of a Subarctic Coast

by Emilie Arseneault, Reinhard Pienitz, Julie Carrière and Émilie Saulnier-Talbot

Hydrobiology 2023, 2(4), 537-553; https://doi.org/10.3390/hydrobiology2040036 - 30 Oct 2023

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Abstract

Diatoms are reliable environmental bioindicators, but their application in coastal environments remains limited. Substrate has been put forward in the literature as an important variable in determining diatom habitat preferences. This study focuses on benthic diatom assemblages and their relationship with substrate specificity in a subarctic tidal environment, which could be relevant for environmental monitoring and management. A variety of substrates were sampled and physicochemical variables measured in various areas of the Bay of Sept-Îles region (northern Gulf of Saint-Lawrence, Canada). We recorded 606 species at 14 sites from 11 substrate types to determine the associations between diatoms and their habitats. Our results suggest that the variability of assemblages in the bay is the result of a combination of the identified variables (temperature, salinity, and total dissolved solids), explaining 26.5% of the variation, and other unmeasured variables (e.g., nutrients, wave action, and currents). Substrate was not identified as a significant variable in the statistical analyses. However, some common species in the surveyed assemblages appeared to show preferences for the substrates they colonized. Full article

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16 pages, 3286 KiB

Open AccessArticle

Total Mass Flux in the Northern Humboldt Current System: Rates and Contribution Sources from Central Peru (12° S)

by Bobby Leigh, Víctor Aramayo, Ursula Mendoza, Federico Velazco, Rainer Kiko, Patricia Ayón, Ernesto Fernández and Michelle Graco

Hydrobiology 2023, 2(4), 521-536; https://doi.org/10.3390/hydrobiology2040035 - 28 Sep 2023

Viewed by 1013

Abstract

The total mass flux (TMF) of particulate organic matter (POM) is key for understanding the energetic transfer within the “biological pump” (i.e., involving the carbon cycle), reflecting a critical connection between the surface and the bottom. A fixed multi-sediment trap was installed at 30 m depth in Callao Bay, central Peru from March to December 2020. After recovery, samples were dried and weighed to calculate the TMF and pellet flux. The average TMF was 601.9 mg·m⁻²·day⁻¹, with 70.2 and 860 mg·m⁻²·day⁻¹ as the lowest and highest values during “normal conditions”. Zooplankton fecal pellets (ZFP) were found in ovoid (e.g., larvae) and cylindrical (e.g., adult copepods) shapes and their flux contribution to TMF was low, ranging from 0.17 to 85.59 mg·m⁻²·day⁻¹. In contrast with ZFP, fish fecal pellets (FFP) were found in fragments with a cylindrical shape, and their contribution to the TMF was higher than ZFP, ranging from 1 to 92.56 mg·m⁻²·day⁻¹. Mean sinking velocities were 4.63 ± 3.47 m·day⁻¹ (ZFP) and 432.27 ± 294.26 m·day⁻¹ (FFP). There is a considerable difference between the ZFP and FFP contributions to TMFs. We discuss the implications of these results regarding a still poorly understood process controlling the POM flux off the Peruvian coast. Full article

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Hydrobiology, Volume 2, Issue 4 (December 2023) – 5 articles

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