Marine Biology最新文献

Floating materials of both natural and anthropogenic origin affect marine ecosystems and human economic activities. Although the tracking of floating materials is important to manage the economic risks, it is difficult to trace them back to the events of origin, such as tsunamis and underwater volcanic eruptions. The gooseneck barnacle Lepas anserifera, a rapid colonizer in pelagic environments, is a potential “natural logger” of floating materials. In this study, we performed temperature-controlled culture experiments and growth line staining in the laboratory to quantify the growth increments of shells (scutum and tergum) consisting the capitulum of L. anserifera separately, and to examine the effects of the temperature on their growth. Following calcein staining, the growth lines of L. anserifera were visualized under a fluorescent microscope, and gross (capitular length and width) and individual (scutum and tergum) shell growth were compared. Shells grew in twice as much in the capitular length direction than in the capitular width direction owing to the larger growth increases in the scutum than in the tergum. Growth increments were unaffected by temperatures in the range from 20°C to 30°C, although the growth appeared to slow down in September and October compared with August. The stable oxygen isotope composition (δ¹⁸O) of the shells represented the water temperature as previously known, and the present results showed that ¹⁸O enriched in scutum than tergum in most cases. Further understanding for the biomineralization process of barnacles is required for the precise application of environmental proxies in barnacle shells.

Understanding the drivers of morphological plasticity, a key mechanism allowing species to flourish under a range of conditions, can provide important information on how a species will adapt to climate-change. The kelp Ecklonia radiata is the dominant canopy-forming macroalgae in temperate Australasia, occurring across a wide environmental range. Previous assessments of morphological variation across Australasia have not included northeastern New Zealand (NENZ) populations, where E. radiata exhibits an anomalous long-stipe morphology. Morphology in NENZ E. radiata over nine locations was quantified to examine variability and its relationship with environmental drivers: depth, wave exposure, turbidity and temperature. Published literature was then reviewed to assess variation across Australasia in relation to similar large-scale environmental drivers. In NENZ, morphology was driven by depth, wave exposure, and turbidity, but not temperature. Thalli had short stipes and relatively long lamina at shallow depths (< 2 m) and across depths at highly wave exposed sites. Stipe length increased with depth and the long stipe morphology dominated deeper depths (4–12 m) at sheltered to moderately exposed sites. However, this relationship varied in relation to turbidity, with more turbid sites having shorter stipes across all depths. Regional variation in morphology across Australasia was most strongly related to wave climate rather than temperature with the long-stipe morphology characterising regions with low energy wave climates such as NENZ. This study highlights the high levels of variability in E. radiata morphology and its complex relationship with environmental stress. If Australasia’s wave climate is to increase in severity, our findings suggest morphological variability expressed across Australasian E. radiata populations will shrink.

Understanding the nutritional quality of macrozooplankton is crucial for elucidating energy and matter fluxes in marine food webs and their value as fish prey. This study examines the seasonal (winter, spring, summer) and spatial variability in three quality indicators -energy density (ED), polyunsaturated fatty acids (PUFA) content, and DHA/EPA ratio- of Euphausia spp. and Grimothea gregaria. These indicators were analyzed in relation to size and environmental variables (temperature, salinity, and chlorophyll-a concentration) in the San Jorge Gulf (45°–47°S, 65°30′-67°30ʹW; Southwest Atlantic Ocean), a key feeding ground for commercially important fish on the Argentine shelf. Results showed that ED increased with size in Euphausia spp. but decreased in G. gregaria. Seasonal changes were the primary drivers of variations in the nutritional quality, with PUFA content being the index most contributing. For both species, the highest mean PUFA content occurred in winter and the lowest in summer, an inverse pattern to ED. The DHA/EPA ratio also peaked in winter and dropped in spring. Species differences significantly affected PUFA content and the DHA/EPA ratio, with Euphausia spp. exhibiting higher values. Although environmental variables, particularly bottom temperature and chlorophyll-a, varied significantly across sampling areas, no clear spatial patterns emerged in the quality indicators, likely due to the limited sample size. These results provide new and baseline information of zooplankton that can clarify the trophic interactions of many fish and their respective predators along the Argentinean Shelf, and how these relationships may change with environmental variability in the current global change context.

Aurelia is a genus of scyphozoan jellyfish with cosmopolitan distribution and a propensity to form large aggregations, or “blooms.” Along the northern Gulf of Mexico (GoM) coast, blooms of Aurelia have caused problems for human enterprise. Mature Aurelia sp. 9 and sp. 18 medusae are observed each season, yet their benthic originators, the polyps, have never been found in nature in the GoM. The absence of information on polyp locations greatly limits our understanding of bloom formation, as we are unable to identify bloom origins or study medusae production in situ. To address the lack of knowledge on polyp distribution, suitable habitats, including natural and artificial settlement substrates for A. sp. 9 and A. sp. 18 were modeled using a GIS spatial analysis, utilizing previously published experimentally derived species’ tolerance ranges for temperature and salinity. Spatial models considered temperature and salinity parameters from surface down to 1500 m utilizing a ¼ degree grid size. The results suggest the GoM coastal waters have suitable environmental parameters for A. sp. 9 but not A. sp. 18 and that water temperature, but not salinity, limits the distribution of both species. Also, 94% of GoM artificial reefs and 97% of gas platforms fell within the modeled distribution range for A. sp. 9, compared to only 37% and 40% for A. sp. 18, respectively. Models suggest that A. sp. 18 may be an offshore species restricted to the deeper shelf waters of the GoM by summer-high water temperatures and that future increases in water temperature, such as those expected with climate change, may negatively impact Aurelia jellyfish populations in the northern GoM.

Coral reef degradation is a worldwide and growing phenomenon triggering habitat transformation from live to dead coral fragments. Macroinvertebrates play key functions in coral reefs, yet research on the size distribution of their community attributes is limited, particularly in the Eastern Tropical Pacific (ETP). We assessed the size distribution of the macroinvertebrate communities in live and dead corals in an ETP coral reef off Colombia. Live coral supported greater macroinvertebrate biomass than dead corals. In live coral, > 90% of total biomass was allocated in the > 8 mm class, which was mostly represented by trapeziid crabs and alpheid shrimps, both obligate symbionts of Pocillopora colonies. No differences were found in macroinvertebrate densities between substrates. Macroinvertebrate communities were dominated by crustaceans, though not in every size class. In live coral, Decapoda dominated in all size classes except 0.5–1 mm, which was the only class where dominance of a single taxon was not observed. In dead corals, the dominance of crustaceans was only observed in the 0.5–1 mm class due to high abundances of tanaidaceans. The remaining size classes were dominated by Polychaeta (1–2 mm, 2–4 mm) and Ophiuroidea (4–8 mm, > 8 mm). Our findings highlight that coral degradation events could lead to macroinvertebrate assemblages with lower biomass contributions, higher proportions of small crustaceans (< 1 mm), and taxonomic shifts. Such transitions from live to dead corals could likely impact food-web interactions between macroinvertebrates and higher trophic levels, potentially altering the ecosystem services offered by coral reefs.

Anthropogenic disturbances are having strong, negative effects on aquatic systems globally, altering ecological communities and potentially creating vacant niches for both native and non-native species (NNS). Globalization and new trade routes have amplified the spread and establishment of NNS by connecting disturbed areas worldwide. In this study, we conducted a comparative assessment of seasonal variations in amphipod communities at three southeastern Baltic Sea locations – two anthropogenically impacted and one protected habitat – to determine if native and NNS diversity differed among these habitats. Our study revealed nine amphipod species - of which two were NNS - across all three habitats. The impacted habitats had significantly higher native species richness and lower NNS abundance. Grandidierella japonica was the only NNS found at the impacted habitas. In the case of the protected habitat, NNS Gammarus tigrinus was dominant for most of the year. In autumn, dominance shifted in favour of the native Gammarus locusta and Microdeutopus cf. gryllotalpa. Grandidierella japonica was not detected there. Although anthropogenically impacted habitats may be under higher invasion risk, other environmental factors, such as salinity and temperature, may be driving the establishment pattern of NNS and the resulting community structures. Furthermore, undisturbed and/or protected habitats may be highly vulnerable to invasions due to more tolerable environmental conditions, robust NNS populations and naïve native species to newcomers. Seasonality is an important aspect of ecological studies and must be taken into account, as omissions could potentially distort our understanding of the dynamics of ecosystems and prevent the detection of NNS.

The paper explores the dynamic relationship between sharksuckers and Atlantic Nurse sharks within a fish cleaning station in South Eleuthera, The Bahamas. Despite the prevalent symbiotic association between echeneid fishes and sharks, the specifics of their interactions, behavioral adaptations, and the influence of food availability remain understudied. The research employed a comprehensive observational approach, focusing on free-swimming and attached sharksucker’ behaviors (Echeneis spp.) in the presence of Atlantic Nurse sharks. Through a month-long study, both qualitative and quantitative analyses of the behaviors were conducted. The results challenge the traditional perception of a purely mutualistic or parasitic relationship, suggesting a more complex dynamic between sharksuckers and sharks. Specifically, the study indicates an increase in boldness and competitive behaviors towards sharks in a controlled feeding setting, indicating that sharksuckers’ behaviors and relationships with their hosts are constantly evolving and should not be treated as simply symbiotic.

Coral reef fishes are usually assumed to be most strongly associated with reef-building corals. However, sponges can be a significant structural component of coral reef ecosystems and their framework can enhance the local abundance and biodiversity of fish assemblages. Little is known regarding the range of fish species using complex sponges as either shelter or feeding substrata. Here we use a combination of stationary video cameras and focal animal sampling to document fish species positively associated with complex sponges in Kimbe Bay, Papua New Guinea. Stationary cameras identified 45 fish species using the sponges for either shelter, feeding substrata or as sites for ambush predation. A guild of 10 individual fish species from five families (Blenniidae, Chaetodontidae, Gobiidae, Labridae and Pomacentridae) were observed to quantify sponge and other habitat use and compared with habitat availability to determine the level of sponge selectivity. One species, Pleurosicya elongata (the Slender Spongegoby), lived in obligate association with Ianthella basta (Elephant Ear sponge), and there was a positive relationship between sponge size and number of resident fish, however this was not significant for all life stages. Five other fish species appeared to preferentially select sponges as habitat (Amblyglyphidodon aureus, Chaetodon kleinii, Coradion chrysozonus, Escenius prooculis and Pomacentrus nigromanus), while for others, sponge use appeared incidental. When selectivity indices were calculated for specific sponge species it was apparent that some fishes exhibited preferences for particular sponge species or growth forms. These results suggest more fish species may be reliant on sponges than is widely appreciated.

Reef manta rays (Mobula alfredi) face threats from human exploitation and activity in several regions of the world and crucial information on the ecology of the species is needed. The species is observed at several sites in all parts of the archipelago of New Caledonia where anthropogenic influence is presumed to be minimal. This study is the first to investigate the population of New Caledonia and focuses on its characteristics and its habitat use. Photographs of reef manta rays were collected directly from the authors (14.4%) between 2017 and 2020 and gathered from recreational divers and snorkelers (85.6%) from 11 sites around New Caledonia. The authors used the unique ventral coloration patterns of the manta rays that were clearly identifiable from 1741 of these photographs to identify 391 individuals and record their physical characteristics (sex, injuries, and colour morph) and resighting rates. These results highlight the widespread distribution of the species in the archipelago (11 sites) with little connectivity between all aggregations sites, with only 5.4% of the individuals observed at more than one site. Strong and long-term site fidelity was recorded at all studied sites through re-sighting rates (52.2% overall) and residency analysis. The population also records the world highest known proportion of melanistic manta rays (43%) to date, and a balanced male: female ratio (1.0:1.15). The analysis of injuries reported that 44.8% of all reef manta rays identified (n = 391) had noticeable wounds or injuries with no significant difference in the proportions of males and females injured. From these injured individuals only 9.8% of injuries judged to be of anthropogenic origin and 29.7% from attempted predation. Our study complements and correlates previous findings on this population that revealed strong site fidelity and low connectivity. The different characteristics of this population of reef manta rays also emphasize that concerns about species in New Caledonia are limited and that such favourable context needs to be preserved as reference for conservation.

In recent years, population outbreaks of the annelid Hermodice carunculata (Polychaeta, Amphinomidae) are recurrently detected along the coastal zone of the Salento peninsula (Southern Italy), with impacts on marine benthic ecosystems. Annelida are renowned for their remarkable regeneration potential, enabling them to reform lost body parts. A handful of studies have reported posterior regeneration of H. carunculata, but anterior regeneration has not been fully explored. In this study, we investigated the capacity of H. carunculata collected in shallow coastal areas (Ionian Sea, 40°08’26.9” N 17°58’44.1” E) to regenerate anterior body parts under different temperature conditions (22 and 14 °C) and considering two different body sizes (∼ 4 g and 25 g). In addition, histological analysis and lipid analyses were carried out to detect changes in the reproductive cycle and lipid storage during ongoing regeneration. The results suggest that small and large-sized specimens of H. carunculata can regenerate efficiently anterior body parts in 12–20 weeks post amputation when kept at 22 °C. Small-sized worms kept at 14 °C regenerated slower but died in 24 weeks post amputation before regenerating a mouth, while large-sized worms kept at 14 °C were affected by a 100% mortality during blastema formation. In addition, lipid extraction analyses show that H. carunculata can regenerate during extended periods of starvation by de novo synthesizing lipid reserves and regeneration in H. carunculata does not negatively impact the reproductive cycle, as gametogenesis occurs also during the regenerative processes.