Among organic pollutants existing in coastal areas, polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their ubiquity and carcinogenic potential. The aim of this study was to evaluate the seasonal patterns of PAHs in the digestive gland and arm of the common octopus (Octopus vulgaris) from the Northwest Atlantic Portuguese coast. In the different seasons, 18 PAHs were determined and the detoxification capacity of the species was evaluated. Ethoxyresorufin O-deethylase (EROD) and ethoxycoumarin O-deethylase (ECOD) activities were measured to assess phase I biotransformation capacity. Individual PAH ratios were used for major source (pyrolytic/petrogenic) analysis. Risks for human consumption were determined by the total toxicity equivalence approach. Generally, low levels of PAHs were detected in the digestive gland and in the arm of octopus, with a predominance of low molecular over high molecular weight compounds. PAHs exhibited seasonality in the concentrations detected and in their main emission sources. In the digestive gland, the highest total PAH levels were observed in autumn possibly related to fat availability in the ecosystem and food intake. The lack of PAH elimination observed in the digestive gland after captivity could be possibly associated to a low biotransformation capacity, consistent with the negligible/undetected levels of EROD and ECOD activity in the different seasons. The emission sources of PAHs found in the digestive gland varied from a petrogenic profile observed in winter to a pyrolytic pattern in spring. In the arm, the highest PAH contents were observed in June; nevertheless, levels were always below the regulatory limits established for food consumption. The carcinogenic potential calculated for all the sampling periods in the arm were markedly lower than the ones found in various aquatic species from different marine environments. The results presented in this study give relevant baseline data for environmental monitoring of organic pollution in coastal areas.
University of Adelaide research into parasites of cuttlefish, squid and octopus has uncovered details of the parasites’ astonishing life cycles, and shown how they may help in investigating populations of their hosts.
Researcher Dr Sarah Catalano has described 10 new parasite species− dicyemid mesozoans −, which live in the kidneys of cephalopods (cuttlefish, squid and octopus). They are the very first dicyemid species to be described from Australian waters.
... (see article)
“We looked at the dicyemids in two species of cuttlefish, the giant Australian cuttlefish and the nova cuttlefish, from various localities in South Australian waters,” Dr Catalano says. “We found different dicyemid species infected each cuttlefish species at different localities, suggesting there are unique populations of each host species in South Australian waters.
“As such, this offers support for the use of dicyemid parasites as biological tags and we hope to be able to use these parasites to tell us more about cephalopod population structure to assist in management plans.”
The present study (Ishigaki Island, Japan) explored the distance of transmission of chemical cues emitted by live versus dead coral reefs (Exp. 1: High performance liquid chromatography (HPLC) analyses with water sampling station at 0, 1, and 2 km away from the reef) and the potential attraction of these chemical cues by larval fish, crustaceans, and cephalopods (Exp. 2: choice flume experiment conducted on 54 Chromis viridis larvae, 52 Palaemonidae sp larvae, and 16 Sepia latimanus larvae). In the experiment 1, HPLC analyses highlighted that the live coral reef (and not the dead coral reef) produced different and distinct molecules, and some of these molecules could be transported to a distance of at least 2 km from the reef with a reduction of concentration by 14–17-fold. In the experiment 2, C. viridis, Palaemonidae sp, and S. latimanus larvae were significantly attracted by chemical cues from a live coral reef (sampling station: 0 km), but not from a dead coral reef. However, only C. viridis larvae detected the chemical cues until 1 km away from the live coral reef. Overall, our study showed that chemical cues emitted by a live coral reef were transported farthest away in the ocean (at least 2 km) compared to those from a dead coral reef and that fish larvae could detect these cues until 1 km. These results support the assumption of a larval settlement ineffective in degraded coral reefs, which will assist conservationists and reef managers concerned with maintaining biodiversity on reefs that are becoming increasingly degraded.
Carbon dioxide (CO2) levels projected to occur in the oceans by the end of this century cause a range of behavioural effects in fish, but whether other highly active marine organisms, such as cephalopods, are similarly affected is unknown. We tested the effects of projected future CO2 levels (626 and 956 µatm) on the behaviour of male two-toned pygmy squid, Idiosepius pygmaeus. Exposure to elevated CO2 increased the number of active individuals by 19–25% and increased movement (number of line-crosses) by nearly 3 times compared to squid at present-day CO2. Squid vigilance and defensive behaviours were also altered by elevated CO2 with >80% of individuals choosing jet escape responses over defensive arm postures in response to a visual startle stimulus, compared with 50% choosing jet escape responses at control CO2. In addition, more escape responses were chosen over threat behaviours in body pattern displays at elevated CO2 and individuals were more than twice as likely to use ink as a defence strategy at 956 µatm CO2, compared with controls. Increased activity could lead to adverse effects on energy budgets as well as increasing visibility to predators. A tendency to respond to a stimulus with escape behaviours could increase survival, but may also be energetically costly and could potentially lead to more chases by predators compared with individuals that use defensive postures. These results demonstrate that projected future ocean acidification affects the behaviours of a tropical squid species.
If you will start a post with your TONMO name and your publication name (you don't need to add more but are welcomed to) in the Member's Publications thread, I will add you to the names I monitor with Google Scholar.
Abstract The market squid, Doryteuthis opalescens, is an important forage species for the inshore ecosystems of the California Current System. Due to increased upwelling and expansion of the oxygen minimum zone in the California Current Ecosystem, the inshore environment is expected to experience lower pH and [O2] conditions in the future, potentially impacting the development of seafloor-attached encapsulated embryos. To understand the consequences of this co-occurring environmental pH and [O2] stress for D. opalescens encapsulated embryos, we performed two laboratory experiments. In Experiment 1, embryo capsules were chronically exposed to a treatment of higher (normal) pH (7.93) and [O2] (242 μM) or a treatment of low pH (7.57) and [O2] (80 μM), characteristic of upwelling events and/or La Niña conditions. The low pH and low [O2] treatment extended embryo development duration by 5–7 days; embryos remained at less developed stages more often and had 54.7% smaller statolith area at a given embryo size. Importantly, the embryos that did develop to mature embryonic stages grew to sizes that were similar (non-distinct) to those exposed to the high pH and high [O2] treatment. In Experiment 2, we exposed encapsulated embryos to a single stressor, low pH (7.56) or low [O2] (85 μM), to understand the importance of environmental pH and [O2] rising and falling together for squid embryogenesis. Embryos in the low pH only treatment had smaller yolk reserves and bigger statoliths compared to those in low [O2] only treatment. These results suggest that D. opalescens developmental duration and statolith size are impacted by exposure to environmental [O2] and pH (pCO2) and provide insight into embryo resilience to these effects.