The acute toxicity of three formulations of commercial detergent (ROMA^®, FOCA^® and BLANCA NIEVES^®) was evaluated using the polychaete Capitella sp. C in static bioassays over a 48-h exposure period. The probit method was used to determine the median lethal concentration (LC₅₀) of each formulation as a whole as well as the LC₅₀ of the active ingredient, linear alkylbenzene sulfonate (LAS), using 95 % confidence intervals. The formulations and LAS showed LC₅₀ values of between 70.79 and 147.91 ppm and 15.48 and 22.38 ppm, respectively, at 48 h. FOCA^® was the most toxic detergent, followed by BLANCA NIEVES^® and finally ROMA^®. The variation in the toxicity of the three detergents could have been caused both by differences in the relative concentrations of the anionic surfactant LAS contained in each formulation and the presence of other ingredients (enzymes, sodium silicate, sodium tripolyphosphate, bleachers and perfumes) which can also increase formulation toxicity. Correlation analysis revealed that percent mortality of Capitella sp. C increased with increase in the concentrations of the detergent over the 48-h exposure period. The risk quotient was greater than one for all three evaluated detergents, indicating that there is a high risk that they adversely affect the aquatic biota, particularly sediment-dwelling organisms such as the test species.

Five Scolelepisspecies from the Gulf of Mexico and Western Atlantic Ocean are reported and certain species previously synonymized with Scolelepis(S.) squamataare revised. Four species are reinstated: S.(S.) goodbodyi(Jones, 1962), S.(S.) minuta(Treadwell, 1939), S.(S.) acuta(Treadwell, 1914), and S.(S.) agilis(Verrill, 1873); and two are described as new: S.(S.) lightin. sp., and S.(S.) vossaen. sp. Scolelepis(Scolelepis) goodbodyi(Jones, 1962) n. comb., S.(S.) minuta(Treadwell, 1939) n. comb., S.(S.) acuta(Treadwell, 1914), and S.(S.) agilis(Verrill, 1873) are removed from synonymy with S.(S.) squamataMüller, 1806. The record of Scolelepis(P.) texanaFoster, 1971 from the Grand Caribbean region is confirmed. A key to all Scolelepisspecies from the Grand Caribbean is provided.

The study of previously unidentified material of Spionidae from the Grand Caribbean region resulted in the discovery of five new species in four genera: Boccardia salazari sp. nov., Dipolydora anatentaculata sp. nov., D. contoyensis sp. nov., Polydora quintanarooensis sp. nov. and Pseudopolydora floridensis sp. nov. Boccardia salazari is characterized by two types of major spine in chaetiger 5, one with expanded end bearing cusps without bristles, the other, simple, falcate; D. anatentaculata is characterized by an occipital antenna, and major spines simple, falcate, without subterminal protuberance; D. contoyensis is characterized by six pairs of branchiae on chaetigers 11–16, major spines with two large accessory teeth on concave and convex sides in chaetiger 5, and pygidium small, glandular, cuff‐shaped with dorsal notch; Polydora quintanarooensis is characterized by two eyes, modified spines of chaetiger 5 falcate, with a lateral tooth, and gizzard‐like structure present at segment 16, and Pseudopolydora floridensis is characterized by two types of major spines in chaetiger 5, first falcate, second pennoned, with both types arranged in U‐shaped, double row, a caruncle extending to chaetigers 6–7, and an occipital antenna. A key to all species of Boccardia, Dipolydora, Polydora and Pseudopolydora from the Grand Caribbean region is provided.

This paper presents a study of freshwater zooplankton biodiversity, deemed as a reliable indicator of water quality. The Guatemalan Lake Amatitlán, currently used as a water source, has shown signs of progressive eutrophication, with perceptible variations of the local zooplankton diversity. Biotic and abiotic parameters were determined at four sites of Lake Amatitlán (Este Centro, Oeste Centro, Bahía Playa de Oro, and Michatoya) in 2016 and 2017. The local composition, the species richness and abundance of zooplankton, and the system environmental parameters were analyzed during both years surveyed. Biological data suggesting eutrophication of this tropical system were obtained, including a high rotifer abundance (11 species: the rotifers Brachionushavanaensis (109 ind L⁻¹) and Keratellaamericana (304 ind L⁻¹) were the most abundant species in this lake). The presumably endemic diaptomid copepod species, Mastigodiaptomusamatitlanensis, was absent in our samples, but we report the unprecedented occurrence of two Asian cyclopoid copepods (i.e., Thermocyclopscrassus and Mesocyclops thermocyclopoides) for Lake Amatitlán and Guatemala. The presence of larger zooplankters like adults and immature copepods (i.e., Arctodiaptomusdorsalis) and cladocerans (Ceriodaphnia sp.) at site “Este Centro” indicates a relatively healthy zooplankton community and represents a focal point for managing the conservation of this lake.

The Yucatan Peninsula (YP) presents heterogeneous environments in a karstic landscape that has been formed from permeable sedimentary rocks dating from the Cretaceous period. Its aquifers now face significant pressure from tourism, agriculture, soil use changes and population growth. Aquifer delimitation typically relies on environmental and socioeconomic criteria, overlooking the subterranean fauna. Stygobiotic crustaceans are highly diverse in the YP’s subterranean karstic systems, expressing adaptations to extreme environments while often also displaying the primitive morphology of evolutionary relics. With distributions restricted to specific environments, they are potential markers of water reserves. A literature review recovered records of 75 species of crustaceans from 132 subterranean systems in the YP, together with geomorphological, hydrological, hydrogeochemical and historical precipitation data. Fourteen UPGMA clusters were informative for mapping species composition, whereby the “Ring of Cenotes”, “Caribbean Cave” and “Cozumel Island” regions were delineated as consolidated aquifers. These aquifers are distinguished by abiotic factors as well: freshwater species dominate the Ring of Cenotes, while marine-affinity species characterize the Caribbean Cave and Cozumel Island aquifers. Stygobiotic crustaceans, being linked to geologically ancient water reserves and having a restricted distribution, offer a complementary tool for aquifer delimitation. Their presence suggests long-term and stable water availability. The use of these unique organisms for integrative aquifer delimitation can provide a way to improve the monitoring networks of regional aquifers.

A re-assessment of spionid specimens collected from coasts around the Iberian Peninsula and initially assigned to Dispio uncinata Hartman, 1951 and Prionospio multibranchiata Berkeley, 1927 resulted in the recognition of two new species from the genera Dispio and Prionospio: Dispio glandulosa sp. nov. and Prionospio (Minuspio) sanmartini sp. nov. In addition, the examination of specimens collected near the type locality of P. multibranchiata led to a re-description of this species. The specimens examined do not correspond to the material collected from the Iberian Peninsula and it is unlikely that P. multibranchiata is found in northern European waters.