Marine Biology最新文献

Intertidal animals deal with physical gradients daily that create stressful conditions across the shore. These physical gradients influence the physiological performance of organisms, requiring responses that may differ with height on the shore. We examined the respiratory response to aerial exposure in the invasive Asian shore crab Hemigrapsus sanguineus during periods of low tide emersion using two field experiments. The first experiment simultaneously measured respiration of individuals collected from different heights on the shore, which had therefore been emersed for different lengths of time. The second experiment measured respiration of individuals collected at different times from the same tidal height. Respiration rates of crabs in both experiments increased immediately after emersion, nearly doubling by and peaking at ~ 1.5 h of aerial exposure, before decreasing again over the next 1.5 h. These results suggest that the energetic cost of low tide exposure is greatest shortly after emersion during the first half of the typical low tide period, but then decreases thereafter. These respiration patterns facilitate the broad intertidal distribution of this species on rocky shores throughout its range.

Animals have a deep evolutionary relationship with microbial symbionts, such that individual microbes or an entire microbial community can diverge alongside the host. Here, we explore these host-microbe relationships in Echinometra, a sea urchin genus that speciated with the Isthmus of Panama and throughout the Indo-West Pacific. We find that the eggs from five Echinometra species generally associate with a species-specific bacterial community and that the relatedness of these communities is largely congruent with host phylogeny. Microbiome divergence per million years was higher in more recent speciation events than in older ones. We, however, did not find any bacterial groups that displayed co-phylogeny with Echinometra. Together, these findings suggest that the evolutionary relationship between Echinometra and their microbiota operates at the community level. We find no evidence suggesting that the associated microbiota is the evolutionary driver of Echinometra speciation. Instead, divergence between Echinometra and their microbiota is likely the byproduct of ecological, geographic, and reproductive isolations.

The grazing impacts of two Acartia species (Acartia omorii and A. steueri) on size-fractionated phytoplankton biomass were measured in Jangmok Bay, Korea (34°59′37.8" N, 128°40′28.2'' E) from January to May 2015. Total chlorophyll (Chl-a) concentrations ranged from 0.66 to 5.18 µg L⁻¹, and micro-phytoplankton (> 20 µm) comprised up to 66% (range, 10.5–65.6%) of the total pigment. The total abundance of Acartia species ranged from 267 to 5931 ind. m⁻³, and these copepods accounted for 20.8 to 88.0% of the total copepod abundance. The ingestion rates of A. steueri (r² = 0.904, P = 0.013) and A. omorii (r² = 0.239, P = 0.046) showed a high correlation with micro-phytoplankton. The average grazing impact of Acartia species on phytoplankton biomass was approximately 6.8 ± 11.8% (range, 0.1–69.0%). Temperature–salinity (T–S) diagram analysis revealed distinct environmental preferences for each species; A. omorii preferred a broader temperature range of 6.2 to 17.1 °C and a salinity range of 31.8 to 33.5, whereas A. steueri was more restricted, preferring temperatures between 6.5 and 12.8 °C and a salinity range of 32.2 to 33.5. These findings not only contribute to our understanding of the ecological roles of these copepod species in marine ecosystems but also highlight the importance of continuous research regarding the mechanisms driving their coexistence and interaction with the coastal food web.

The ecological importance of rhodolith beds stems from their role as structurally complex three-dimensional habitat formed by free-living red calcareous algae. Their structural singularity is due to the great variety of complex and branching morphologies exhibited by rhodoliths that create interstitial spaces and increase their surface area. This increases the ecological niches for cryptofauna and provide refuge for a high number of organisms, which is why rhodolith beds are considered biodiversity hotspots. In this work, we studied a rhodolith bed located in the Menorca Channel, formed by several species of red calcareous algae that exhibit a great variety of morphologies and form an extensive and heterogeneous habitat. This study explored the morphological diversity of the rhodolith bed, comparing the ‘Core Habitat’ (within the center of the bed with the highest densities of rhodoliths) with the boundaries or ‘Adjacent Habitat’ where rhodolith density was lower. Our results show that all rhodolith growth forms (branched, pralines and boxwork) in the Core Habitat had higher interstitial space and were larger than the ones from adjacent zones. Moreover, we explored the three-dimensional techniques to study the morphological characteristics that have historically been studied in two dimensions. This study contributes to the knowledge of morphological diversity in well-preserved rhodolith beds from continental shelves in the western Mediterranean Sea and reinforces the use of three-dimensional measurements, specifically the interstitial space of branched rhodoliths, to provide more accurate data on habitat complexity.

Many dinoflagellate species are bioluminescent, which is one of the anti-predation mechanisms in these species. In addition, dinoflagellate species experience a wide range of salinities in the ocean. However, the effects of salinity on their bioluminescence intensity has only been investigated for one species. Here, we explored the effect of salinity on the bioluminescence intensity of the heterotrophic dinoflagellate Noctiluca scintillans NSDJ2010 feeding on the chlorophyte Dunaliella salina, the heterotrophic dinoflagellate Polykrikos kofoidii PKJH1607 feeding on the dinoflagellate Alexadrium minutum, and the autotrophic dinoflagellate Alexandrium mediterraneum AMYS1807. Moreover, to determine the cell volume and growth effects on bioluminescence intensity, the cell volume and growth rate of three bioluminescent dinoflagellates were simultaneously investigated. The mean 200-s-integrated bioluminescence intensity (BL) per cell, equivalent to the total bioluminescence, of N. scintillans, P. kofoidii, and A. mediterraneum was significantly affected by salinity and increased with increasing salinity from 10 to 40. The results of the present study suggest that the total bioluminescence of N. scintillans, P. kofoidii, and A. mediterraneum in offshore and oceanic waters is greater than that in estuarine waters.

Comprehending how environmental variability shapes foraging behaviour across habitats is key to unlocking insights into consumer ecology. Seabirds breeding at high latitudes are exemplars of how marine consumers can adapt their behaviours to make use of predictable foraging opportunities, but prey tends to be less predictable in tropical oceanic ecosystems and may require alternative foraging behaviours. Here we used GPS and time-depth recorder loggers to investigate the foraging behaviour of central placed adult red-footed boobies (Sula sula rubripes), a tropical seabird that forages in oceanic waters via diving, or by capturing aerial prey such as flying fish in flight. Dive bout dynamics revealed that red-footed boobies appeared to exploit denser, but more sparsely distributed prey patches when diving further from the colony. Furthermore, although we found no evidence of environmentally driven habitat selection along their foraging routes, red-footed boobies preferentially dived in areas with higher sea surface temperatures and chlorophyll-a concentrations compared to conditions along their foraging tracks. This multi-scale variation implies that habitat selection differs between foraging routes compared to dive locations. Finally, red-footed booby dives were deepest during the middle of the day when light penetration was greatest. Ultimately, we highlight the importance of gaining insights into consumer foraging across different ecosystems, thereby broadening understanding of how animals might respond to changing environmental conditions.

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.