Marine Biology最新文献

Body colouration, a trait under strong selection, is influenced by the visual background of the environment. The stable influence of depth on visual background dynamics is due to light attenuation along the water column. Depth is also a key factor driving diversification in Sebastes rockfishes, influencing variations in several biological traits. Comparisons between closely related species suggest that brightly coloured species (red, orange, or yellow) tend to inhabit deeper waters and have slower growth rates compared to their shallow-water counterparts with dominance of dark colours (black, brown, or grey). Here, we used 377 photos from 100 Sebastes species, along with recently developed methods of colour quantification and phylogenetic comparative analyses, to assess this trend. Our analyses confirmed the separation of body colouration regarding depth, which was accompanied by differences in growth rates and morphological traits. This indicated that variations in body colourations are included in the ongoing correlational selection process dictated by depth. Analyses of closely related species indicated that depth is an initial driver of colour differentiation and that colour differences do not progressively increase with genetic divergences. We hypothesized that the bright-coloured rockfishes are found in deeper waters because in shallow environments they are more vulnerable to the potential negative effects of UV radiation and higher predation risk, while their predation successes are lessened, in comparison to dark-coloured rockfishes. Overall, this study emphasizes the intricate relationship between genetics, environment, adaptation, and the striking diversity of body colourations observed in Sebastes rockfishes.

Determining flight heights for seabirds is a crucial prerequisite for understanding collision risks associated with offshore wind farms and other human made infrastructure, but obtaining accurate and precise estimates of flight height distributions from observational data remains a challenge. Humphries et al. (Mar Biol 170:1–16, 2023) propose a workflow to determine flight heights of seabirds from digital aerial video images using single-camera photogrammetry. However, their workflow does not adequately consider the impact of uncertainty about seabird body sizes on individual flight height estimates. As a result the proposed method substantially underestimates the uncertainty of individual flight height estimates and yields biased estimates of both the proportion of birds at collision height, and average flight heights. The validation of the proposed method is insufficient and therefore unable to identify or quantify these shortcomings. Based on a review of seabird biometrics, we further argue that even when uncertainty in seabird body size is correctly propagated, the accuracy and precision of flight height estimates from single-camera photogrammetry data is fundamentally limited by the large natural body size variation of seabirds. Digital aerial surveys are an important observational tool to survey marine bird populations, but the workflow proposed by Humphries et al. (2023) for flight height estimation from single-camera digital aerial survey data is biased and does not sufficiently account for uncertainty, and we strongly advise against its use in the current form, for offshore development assessments.

The eastern North Pacific is simultaneously experiencing ocean warming (OW) and ocean acidification (OA), which may negatively affect fish early life stages. Pacific cod (Gadus macrocephalus) is an economically and ecologically important species with demonstrated sensitivity to OW and OA, but their combined impacts are unknown. Through a ~ 9-week experiment, Pacific cod embryos and larvae were reared at one of six combinations of three temperatures (3, 6, 10 °C) and two CO₂ levels (ambient: ~ 360 μatm; high: ~ 1560 μatm) in a factorial design. Both embryonic and larval mortality were highest at the warmest temperature. Embryonic daily mortality rates were lower under elevated CO₂ and there was no effect of CO₂ level on larval daily mortality rates. Growth rates of young larvae (0 to 11 days post-hatch) were faster at warmer temperatures and at high CO₂ levels, but growth during the 11–28 days post-hatch interval increased by temperature alone. The condition of larvae decreased with age, but less markedly under high CO₂ levels. However, at 6 °C, fish incubated in ambient CO₂ remained in higher condition than fish in the high CO₂ treatment throughout the experiment. Overall, temperature had the greater influence on Pacific cod early life stages across each measurement endpoint, while CO₂ effects were more modest and inconsistent. Subtle developmental differences in larval Pacific cod could be magnified later in life and important in the context of recruitment. These results show the complexity of stage- and trait-specific responses to and value of investigating the combined effects of co-occurring climatic stressors.

Temperature is an important environmental factor for phytoplankton. Phytoplankton growth, metabolism, biodiversity, productivity, and distribution are influenced by temperature-driven nutrient stratification and mixing, as well as species’ optimal growth temperatures. There have been a number of studies focused on physiological and biochemical mechanisms of environmental–biological interactions in diatoms, yet the underlying transcriptional regulators remain limited. Here, we performed an RNA-seq-based gene expression analysis to explore the Skeletonema marinoi (isolated from Jiaozhou Bay of Qingdao, 36.13°N, 120.16°E on July 5th, 2013) cellular responses induced by low temperature (12 °C). Digital gene expression profiling of S. marinoi generated 20,319 unigenes, of which 573 differentially expressed genes appeared in the low-temperature treatment group. According to GO and KEGG enrichment analysis, different genes were involved in ten metabolic and biosynthesis pathways: ribosome, lipid, porphyrin, and chlorophyll metabolism showed strong transcriptional cold tolerances. The regulation of genes related to translation processes (e.g., pentatricopeptide repeat), fatty acid metabolism (e.g., acyl-CoA synthetase), and photosynthesis (e.g., porphyrin enzymes) provides new molecular-level insight into cold stress responses in eukaryotic marine phytoplankton. Our study suggests that this Skeletonema species could be a potential candidate for understanding the fate of thermo-sensitive diatom communities and oceanic ecosystems facing climate change.

Mass bleaching events are growing in duration and intensity. Besides causing extensive mortality, the progressively shorter time between events disrupts the ability of reefs to recover. The unique reefs of the Southwestern Atlantic are often considered climate refugia as they have suffered less bleaching-related mortality when compared to Indo–Pacific and Caribbean reefs. However, their recovery capacity still requires investigation. In 2019, an unprecedented heatwave triggered the most severe bleaching episode recorded for Southwestern Atlantic reefs. Therefore, this study aimed to (i) document the bleaching incidence and mortality during the heatwave, and (ii) assess coral recovery over 3 years. We measured bleaching incidence and monitored coral cover through surveys in three Southern Bahia (central Brazilian coast) reefs before, during and after thermal stress. Our findings show that coral assemblages were exposed to a 5-month-long thermal anomaly, experiencing thermal stress peaking at 14.1 ºC-weeks. Roughly 70% of the coral cover was bleached, resulting in a decline of ~ 40%. Millepora alcicornis, Mussismilia braziliensis, and Mussismilia harttii were among species that mortality exceeded 50%. After 3 years, corals showed no increase in cover neither at assemblage nor species levels. This constrained recovery capacity may indicate the breakdown of the refugium, and also trade-off for resistance. Typical features of the region, such as high turbidity and the dominance of massive corals, provide these reefs with bleaching resistance, but likely also limit their recovery. With the anticipated effects of the 2023–24 El Niño–Southern Oscillation in the southern hemisphere, still unrecovered Southwestern Atlantic reefs face a substantial challenge.

The Iberian harbour porpoise (Phocoena phocoena meridionalis) population faces unique challenges, characterized by low population size and limited genetic diversity, underscoring the urgency of conservation efforts. However, a dearth of ecological information on this population hampers targeted conservation measures. This study addresses this knowledge gap by assessing the environmental and anthropogenic factors influencing the habitat use of Iberian harbour porpoises. Utilizing data collected from 195 daily boat surveys spanning 8 years along the north-western coast of Spain, we observed 287 harbour porpoise groups comprising 1383 individuals. Our analysis revealed a wide distribution of harbour porpoises along the continental shelf of the north-western Iberian Peninsula. Notably, this species exhibited a preference for areas characterized by high productivity, influenced by seasonal coastal upwelling phenomena and tidal flow. Our results emphasize the positive correlation between the presence of fishing boats and porpoise habitat use, highlighting the risks associated with bycatch in gear such as bottom-set gillnets and trammel nets, and the need for comprehensive mitigation measures. Additionally, our findings underscore the necessity for comprehensive conservation strategies to address risks associated with marine traffic and habitat alteration due to the expanding development of offshore wind farms in the region. This research also establishes a baseline for future environmental monitoring programs, contributing to the long-term conservation and management of the Iberian harbour porpoise population.

Copepods are a major component of metazooplankton and important prey for fish and invertebrates such as crabs, shrimps, and flatworms. Certain bloom-forming dinoflagellates can kill copepods, but there is little research on the interactions between copepods and the bloom-forming dinoflagellates Karenia bicuneiformis and K. selliformis. In this study, the survival and ingestion rates of the calanoid copepod Acartia hongi feeding on K. bicuneiformis and K. selliformis were determined as a function of prey concentration. On day 2, the survival of A. hongi incubated with K. bicuneiformis was 90–100% at all the tested prey concentrations, while that with K. selliformis was 0–20% at ≥ 582 ng C mL⁻¹. Compared to other harmful dinoflagellates from the literature, K. bicuneiformis caused low mortality of Acartia; however, K. selliformis caused almost the highest mortality at similar dinoflagellate concentrations. With increasing mean prey concentration, the ingestion rates of A. hongi feeding on K. bicuneiformis increased on day 1, but those on K. selliformis did not increase. Acartia hongi stopped feeding on K. bicuneiformis at mean prey concentrations of ≥ 341 ng C mL⁻¹ and K. selliformis at all prey concentrations on day 2. At the prey concentration of 1000 ng C mL⁻¹, the ingestion rate of A. hongi feeding on K. bicuneiformis was moderate among the rates of Acartia spp. feeding on harmful dinoflagellates; however, that on K. selliformis was the lowest. These results indicate that K. bicuneiformis and K. selliformis differentially affect the survival and ingestion rates of A. hongi.

The Atlantic dog whelk, Nucella lapillus, is a marine snail that exhibits divergent evolution in response to habitat adaptation, resulting in distinct populations at the phenotypic, genotypic, and karyotypic levels. In this study, we utilized short- and long-read NGS data to perform a de novo assembly of the entire mitochondrial genome of N. lapillus and developed a multiplex PCR protocol to sequence most of its length using ONT sequencing. Our analysis revealed a typical circular configuration of 16,474 bp in length with 13 protein-coding genes, 22 different tRNA genes, 2 of them showing two copies, 2 rRNA genes, and a control region. Long-read sequencing enabled us to identify a 1826 bp perfect inverted repeat within the control region. Comparative analysis of the mitogenomes of related species in the Muricidae family revealed a conserved gene configuration for N. lapillus. We found a low genetic diversity, as well as a moderate genetic differentiation among the studied populations. Interestingly, there was no observed differentiation between the two chromosomal races, suggesting either introgression and permanent incorporation of the mitochondrial DNA haplotype from one of the chromosomal races into the other or a slower evolutionary rate of the mtDNAs with respect to that of the karyotypes. Our study serves as a foundation for comparative genomics and evolutionary investigations in this species.

Observations of Black Spot Syndrome (BSS), a pigmented dermatopathy in marine fishes, have been increasingly reported in important grazers such as surgeonfish and parrotfish in the Caribbean. This condition has been linked to infection by the trematode parasite, Scaphanocephalus spp., although relatively little is known about the environmental drivers of infection and how they vary spatially. This study introduces a non-invasive, video-based method to survey BSS presence and severity in ocean surgeonfish (Acanthurus tractus). Application of the approach across 35 coastal sites in Curaçao was used to evaluate the influence of environmental factors on BSS, including longitude, herbivorous fish density, wave energy, depth, nutrient pollution, and inhabited surface area. Of the 5123 fish surveyed between February 2022 and January 2023, 70% exhibited visible signs of BSS, and the average number of lesions per fish increased by ~ fivefold from eastern to western sites along the leeward coastline. Within a site, estimates of BSS severity were broadly consistent between different divers, different reviewers of video footage, and the date of sampling, emphasizing the robustness of the surveillance approach. Analyses of environmental factors indicated that BSS decreased with wave intensity while increasing in association with higher nutrient runoff and fishing pressure. This study provides insight into environmental correlates of BSS severity while highlighting the use of video-based surveillance as a non-invasive survey method. The mechanisms linking environmental factors with BSS as well as its consequences for affected fish remain unknown, emphasizing the need for long-term and experimental studies in this system.

Abstract

Population outbreaks of zoantharians in shallow water reefs have been observed globally, including intertidal and subtidal sites in the Canary Islands. This study investigated how zoantharians might be integrating into the local trophic network. For that purpose, we assessed the feeding patterns of common species in zoantharian-dominated habitats, focusing on finding consumers of Zoanthus pulchellus and Palythoa caribaeorum. Through DNA-barcoding and metabarcoding, the gut contents of 11 predatory species were analysed, aiming to characterize their diets and explore local species feeding on zoantharians. Analyses of diet revealed a diverse range of food items and trophic positions of some of the most common and frequent marine species in the archipelago. Furthermore, based on previous observations on the different impacts of Z. pulchellus and P. caribaeorum on shallow benthic ecosystems of the Canary Islands, a preliminary approach to identify their potential influence on feeding patterns of associated species was made. Even though DNA-metabarcoding did not detect zoantharians in the gut contents of any studied species, Sanger sequencing with zoantharian-specific primers indicated their consumption by subject species may be limited to only the crab Platypodiella picta. In addition, by focusing on some of the most common species, this study enhances our understanding of the local trophic network and provides an insight into trophic dynamics in zoantharian-dominated habitats.