The Marine Life Information Network

Temperature increase (local)

Benchmark. A 5°C increase in temperature for one month, or 2°C for one year. Further detail

Evidence

Cephalopods have a poikilothermic metabolism that rises or falls directly with temperature (Forsythe, 1993; cited in Bloor et al., 2013).  For example, an increase of 6°C results in a doubling of individual feeding rate (Pascual, 1978). Cuttlefish in the English Channel have lower mitochondrial capabilities compared to subtropical Adriatic species but have larger hearts, which improve their energetic efficiencies. This allows them to extend their thermal tolerance (Oellermann et al., 2012). It has been estimated that the temperature limits of Sepia officinalis are 10 and 30°C (Guerra, 2006).

In the Ria Formosa, Portugal, water temperature reaches 27°C in the summer Lagoon system. The observed number of Sepia officinalis infers they can survive high water temperatures (Domingues et al., 2002).  Water temperature reached 30°C during the hottest day but no mortality was recorded. However, as temperatures rose in the Cíes Islands, Spain, the probability of finding eggs decreased. Instead, individuals in the Mediterranean prefer a spawning temperature of 12.5 – 14.75°C, similar to that of peak spawning in the English Channel (Guerra et al., 2016b).

Embryonic development increases rapidly with an increase in temperature. At 17°C cultures, embryonic development took 56 days, resulting in a hatchling length of 8.4 mm mantle length (ML). In contrast, an increase in temperature to 20°C resulted in embryonic development taking just 40 days with hatchlings measuring a shorter 7.9 mm ML (Dickel et al., 1997). Warmer waters are, therefore, associated with a shorter incubation time (Sykes et al., 2006 b). However, a reduction in size could make the hatchlings more vulnerable to predation, reducing recruitment (Bouchaud, 1991).

Sensitivity assessment. Sepia officinalis appear to be able to withstand high temperatures. However, for an extended period of time, it could affect their behaviour, development and recruitment. Therefore, resistance is scored as ‘Medium’. Resilience is likely to be ‘Medium’ and sensitivity is, therefore, ‘Medium’.

Temperature decrease (local)

Benchmark. A 5°C decrease in temperature for one month, or 2°C for one year. Further detail

Evidence

In the English Channel, water temperatures are known to get as low as 4°C in coastal areas (CEFAS, 2010, cited in Bloor et al., 2013). A decrease in water temperature was directly correlated with the offshore migration of Sepia officinalis during winter months (Wang et al., 2003). In the Adriatic Sea, where temperatures rarely fall beneath 12°C, no seasonal migration has been observed (Wolfram et al., 2006).  Individuals also reach sexual maturity later in colder waters (Boletzky, 1983), with a preferred spawning temperature of 9.5 – 20°C (Paulij et al., 1990).

It has been estimated that the temperature limits of Sepia officinalis are 10 and 30°C. Below 10°C individuals do not appear to feed and remain inactive until ultimate mortality (Guerra, 2006). Individuals hatched in lower temperatures also have less inner yolk, presumably due to the increase in embryonic development time. This means once hatched the juveniles are under more pressure to gather food (Guerra, 2006). Embryos ceased development when cultured at 9°C. However, when the temperature was raised development continued, which suggested that eggs could almost go into a ‘hibernation’ period under lower temperatures. It is not known how long this period can last for before mortality (Bouchaud & Daguzan, 1990; Challier et al., 2004). Oxygen demand for embryos is also increased at lower temperatures making embryos in colder water more susceptible to hypoxic conditions within the egg sac (Woods, 1999; cited in Lesser, 2013).

Sensitivity assessment: Sepia officinalis appear to be able to survive at low temperatures but suffer mortality after prolonged exposure to 10°C or lower. However, as temperatures decrease in coastal waters individuals may be expected to retreat to deeper waters, with the development of eggs and recruitment potentially affected. Therefore, resistance is scored as ‘Medium’. Resilience is likely to be ‘Medium’ and sensitivity is, therefore ‘Medium’.

Salinity increase (local)

Benchmark. A increase in one MNCR salinity category above the usual range of the biotope or habitat. Further detail

Evidence

Sepia officinalis inhabits oceanic waters that are of full salinity and is unlikely to experience an increase of salinity. In addition, this species is mobile and is, therefore, unlikely to remain in areas of salinity higher than 37 psu (e.g. from hypersaline effluents). Therefore, it is probably ‘Not Sensitive’ at this benchmark level (i.e. resistance and resilience are ‘High’)

Salinity decrease (local)

Benchmark. A decrease in one MNCR salinity category above the usual range of the biotope or habitat. Further detail

Evidence

Adults have been observed to tolerate brackish water, especially during inshore spawning periods. Adult individuals have been observed in the Ria de Vigo (NW Spain) where salinity in the inlet can range from 20-35 PSU. Despite this, eggs have been laid in this inlet (Guerra & Castro, 1998). Nevertheless, the preferred spawning salinity is reported to be 28 or greater (Paulij et al., 1990).

Adult Sepia officinalis are able to survive in salinities of 18 PSU but only if acclimatised slowly (Guerra & Castro, 1988). However, adults are sufficiently mobile and are able to move to a new area if conditions are unfavourable. Juveniles are thought to have a higher plasticity to changes in salinity allowing them to live in more sheltered lagoons with higher freshwater influxes (Paulij et al., 1990). However, normal embryonic development requires salinities above 24 ppt (Paulij et al., 1990). Below 22.4 PSU malformed embryos were observed and the development rate of embryos was reduced even at 28.7 PSU. This is due to an increase in osmotic stress and a resultant reduction in available energy reserves (Paulij et al., 1990). The highest percentage of healthy hatchlings was found at salinities of 29.8 PSU (Paulij et al., 1990). Therefore, in culture, the optimum working salinity range is 27 – 35 PSU (Sykes et al., 2006(b)).

Sensitivity assessment. It appears that adults and juvenile cuttlefish are able to survive in areas with a decrease from full salinity of ca. 10 PSU. However, embryos appear to be more sensitive to a decrease in salinity and adults can reduce their spawning or have a decreased growth rate. The short life span of this species, an annual reproductive cycle and its high fecundity means that recovery should take a year. Therefore, resistance to this pressure is ‘Medium’. Resilience is probably ‘Medium' and sensitivity is, therefore ‘Medium‘.

Water flow (tidal current) changes (local)

Benchmark. A change in peak mean spring bed flow velocity of between 0.1 m/s to 0.2 m/s for more than one year. Further detail

Evidence

Young hatchlings of only a month old responded to strong tidal currents by burrowing in the sand. Komak et al. (2005) reported a lack of migration and movement of juveniles under strong, turbulent, conditions. Therefore, it is important that juveniles have the ability to attach or bury deep enough in the substratum to withstand strong water movement (Boletzky, 1983). Adults were observed to align their bodies parallel to water flow when placed in a flow of 0.08 m/s even when this opposed the pattern of the background (Shohet et al., 2006).

Sensitivity assessment. Sepia officinalis does not appear to be negatively affected by a change in tidal current, therefore, this species is probably ‘Not Sensitive’ with a ‘High’ resistance and a 'High' resilience. 

Emergence regime changes

Benchmark.  1) A change in the time covered or not covered by the sea for a period of ≥1 year or 2) an increase in relative sea level or decrease in high water level for ≥1 year. Further detail

Evidence

Sepia officinalis are sublittoral and so will not be affected by an increase in emergence at the benchmark level. The species is fast moving and will avoid emergence.  Sepia officinalis embryos encased in eggs can be transported for culture for up to 8.5 h in damp or dry conditions or in seawater. Observations of a reduction in oxygen consumption are thought to protect the developing embryos from the damp and dry conditions. The survival rate of transported eggs was 83 – 86% for both eggs kept in water or in dry conditions (Jones et al., 2009).

Sensitivity assessment. Therefore, resistance is probably ‘High’, resilience is ‘High’ (by default) and this species is assessed as ‘Not Sensitive’ at the benchmark level.

Wave exposure changes (local)

Benchmark. A change in near shore significant wave height of >3% but <5% for more than one year. Further detail

Evidence

In rough weather, cuttlebones are often found washed up on beaches. This may mean that some of the population are destroyed when wave exposure increases or it could cause the already, naturally, deceased to wash up. Despite these observations, the species is sufficiently mobile to be able to move to deeper water if conditions are unfavourable. Therefore, resistance is probably ‘High’, resilience ‘High’ (by default) and this species is assessed as ‘Not Sensitive’ at the benchmark level.

Transition elements & organo-metal contamination

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

‘Not Assessed’

Hydrocarbon & PAH contamination

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

‘Not Assessed’

Synthetic compound contamination

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

‘Not Assessed’

Radionuclide contamination

Benchmark. An increase in 10µGy/h above background levels. Further detail

Evidence

No evidence

Introduction of other substances

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

‘Not Assessed’

De-oxygenation

Benchmark. Exposure to dissolved oxygen concentration of less than or equal to 2 mg/l for one week (a change from WFD poor status to bad status). Further detail

Evidence

Sepia officinalis survived 60 mins in tanks at 50% of normal dissolved oxygen, 16.28 mg/l (Capaz et al., 2017). However, Sepia officinalis reduced their oxygen consumption to 37% and increased their ventilation rate to 85%. Metabolic rate subsequently decreased and a minor increase in anaerobic respiration was shown by an accumulation of octopine (lactic acid) (Capaz et al., 2017). Surprisingly, there was no recorded stress response of the animal (no increase in heat-shock protein 70). Capaz et al. (2017) suggested a lack of stress associated with a decrease in dissolved oxygen. Oxygen extraction from ambient water at 17°C is thought to be 70% (Melzner et al., 2006). Cephalopods also appear to have a more highly closed pressurised vascular system compared to other molluscs allowing them to distribute the O₂ taken up by the gills (Häfker, 2012).

Sepia officinalis will be vulnerable to areas of hypoxia when migrating inshore to sheltered bays and estuaries in order to spawn (Guerra, 2006). Boletzky (1981) suggested that the oxygen saturation of the surrounding water must be close to full saturation for efficient development and successful sexual maturity. Sepia officinalis embryos are encased in a protective egg-case which protects it from infection, certain predation and acts as a barrier for gas diffusion (Cronin & Seymour, 2000, Catarina et al., 2017). During the end of embryonic development, oxygen consumption significantly increases, relying heavily on a good supply of dissolved oxygen from the surrounding waters at levels as close to saturation as possible (Cronin & Seymour, 2000). Sepia officinalis embryos encased in eggs can be transported for culture for up to 8.5 hr in damp or dry conditions or in seawater. A reduction in oxygen consumption is thought to protect the developing embryos from the damp and dry conditions. The survival rate of transported eggs was 83 – 86% for both eggs kept in water or in dry conditions (Jones et al., 2009). It must be reminded that this is a mobile species and, therefore, after hatching the likelihood of remaining in an area of low oxygen is unlikely.

Sensitivity assessment. Sepia officinalis appears to be adapted to survive in a dissolved oxygen concentration of 16.28 mg/l by reducing their oxygen consumption or moving away from the area. This, however, is higher than the benchmark of 2 mg/l for this pressure. De-oxygenation is thought to affect the development of embryos. Therefore resistance is assessed as ‘Medium’ due to the potential effect on recruitment. Resilience is probably ‘Medium’ and sensitivity is, therefore ‘Medium’.

Nutrient enrichment

Benchmark. Compliance with WFD criteria for good status. Further detail

Evidence

Refers to the increased levels of nitrogen, phosphorus and silicon in the marine environment. Nutrient enrichment from pollution and other sources can lead to an increase in algal blooms. In turn, this can lead to periods of deoxygenation (see deoxygenation pressure). No evidence on the effect of nutrient enrichment specific to this species was found. However, the species is considered to be 'Not sensitive' at the pressure benchmark that assumes compliance with WFD criteria for good status.

Organic enrichment

Benchmark. A deposit of 100 gC/m²/yr. Further detail

Evidence

Organic enrichment encourages the productivity of suspension and deposit-feeding detrivores and allows species to colonize the affected area to take advantage of the enhanced food. Suspended organic material in the water column will eventually settle on the seabed. However, this has the potential to deoxidize the benthic environment due to the decomposition of the material causing hypoxia (Riera et al., 2013). Sepia officinalis is mostly a mobile demersal species and will probably avoid areas if hypoxia. Therefore, this species at this benchmark is likely to be ‘Not Sensitive’ (see de-oxygenation).

Physical loss (to land or freshwater habitat)

Benchmark. A permanent loss of existing saline habitat within the site. Further detail

Evidence

Adult Sepia officinalis are able to migrate from offshore habitats to inshore, but can also choose where they would like to lay their eggs. This means that if an environment is not suitable, the individual will continue moving in order to find a more suitable location to live and/or spawn (Bloor et al., 2013).

Eggs, hatchlings and juveniles are more vulnerable to the permanent loss of a habitat due to their preference for a particular environment (Camou, 2001). If a structure was to suddenly be placed or an area of land claimed then this would result in the immediate mortality of any small individuals/eggs in that area. Without shallow, sandy, areas recruitment potential may be reduced due to limitation for space and resources (see habitat removal).

Sensitivity assessment. Adults are unlikely to be directly affected by the physical loss of an area as they have highly mobile abilities. Juveniles, hatchlings and eggs are more vulnerable to immediate mortality and a lack of available habitat to survive. Therefore, the resistance is assessed as 'Medium' but with 'low' confidence. Resilience is probably 'Medium' and sensitivity is, therefore, 'Medium'.

Physical change (to another seabed type)

Benchmark. Permanent change from sedimentary or soft rock substrata to hard rock or artificial substrata or vice-versa. Further detail

Evidence

Hatchlings bury themselves in response to threats (e.g. predators) due to their lack of ability to camouflage or flee (O’Brien et al., 2017). Therefore, newly hatched embryos and developing juveniles require sandy substrata to avoid predation. Duration of digging also takes far longer in gravel compared to fine sand and some cuttlefish even refuse to bury into gravel making them vulnerable to predation (Mather, 1986). Juveniles and eggs are usually placed in sheltered areas such as seagrass beds. This reduces their vulnerability to predation and the impact of tides and water surges (Jackson et al., 2001). Without such shelters mortality is likely to occur, reducing recruitment. A lack of an appropriate environment for offspring may result in the female choosing not to lay any eggs at all reducing potential recruitment for the following population (Bloor et al., 2013).  However, adults are highly mobile and, therefore, unlikely to be affected by a change in substratum since it can relocate to more favourable conditions.

Sensitivity assessment. Resistance is probably ‘Medium’, however, confidence is ‘Low’ due to lack of evidence of mortality. Due to the lack of overlap in generations, survival of hatchlings is vital for replenishment and recruitment, therefore, resilience is considered ‘Medium’ and sensitivity is assessed as ‘Medium’.

Physical change (to another sediment type)

Benchmark. Permanent change in one Folk class (based on UK SeaMap simplified classification). Further detail

Evidence

Adult Sepia officinalis will not be affected by a change in sediment class due to the species being highly mobile. However, juveniles rely heavily on sandy bottoms in order to shelter and hide from predation (see juveniles). A change in sediment class has not, however, shown to result directly in an increase in mortality rates.

Sensitivity assessment. Hatchlings and juveniles are probably the most vulnerable to this pressure, as a change to muddy, coarse or hard substratum may increase their vulnerability to predation, therefore, resistance is assessed as ‘Medium’ but with ‘Low’ confidence due to a lack of evidence. Resilience is probably ‘Medium’ and sensitivity is, therefore, ‘Medium’.

Habitat structure changes - removal of substratum (extraction)

Benchmark. The extraction of substratum to 30 cm (where substratum includes sediments and soft rock but excludes hard bedrock). Further detail

Evidence

The act of physically removing the substratum e.g. by dredging may affect the cuttlefish (see physical disturbance). The ability of juveniles to attach themselves onto hard substratum is very important in ensuring they can withstand strong water movements (Boletzky, 1983). Juveniles and hatchlings also need to burrow into sandy substratum in order to avoid predation (Boletzky, 1983). There is also the risk that hatchlings and eggs buried or attached to the substratum will be removed along with the substratum resulting in mortality.

Sensitivity assessment. The loss of habitat is unlikely to affect mobile adults but may damage or remove eggs, hatchlings and/or juveniles, reducing recruitment and further spawning due to a lack of suitable substratum. Therefore, resistance is likely to be ‘Low’ but with ‘low’ confidence due to a lack of evidence. Resilience is probably ‘Medium’ and sensitivity is, therefore, ‘Medium’.

Abrasion / disturbance of the surface of the substratum or seabed

Benchmark. Damage to surface features (e.g. species and physical structures within the habitat). Further detail

Evidence

Cuttlefish have a soft, unarmoured body making them vulnerable to damage and injury (Hanlon & Messenger, 1991; Cooke & Tonkins, 2015). The cuttlebone is able to repair itself and maintains buoyancy so that cuttlefish can withstand a certain amount of internal bone injury (Boletzky & Overath, 1991).

Individuals observed after mating and after entanglement in nets typically have soft tissue damage that suggests susceptibility to abrasive damage (Guerra et al., 2016b). In a southern otter trawl, 77% of the landed Sepia officinalis were discarded suggesting high levels of damage occurring from these trawls (Guerra et al., 2016b). CEFAS has recorded discards of cuttlefish in the English Channel from 6% to 23% of total catch since 2002 (ICES, 2012). Enever et al. (2007) showed that Sepia officinalis was the second most discarded species under the top ten most discarded English Channel species by beam trawlers.

Sepia officinalis from a large beam trawler operating in the offshore waters of south-west UK were examined during a single fishing trip for signs of damage and survival (Revill, 2011). Analysis showed that 16% of these small cuttlefish (<15 cm) died later after their injuries from capture, 68% died whilst in the trawl or on the deck, and only 16% survived capture and deck sorting and were expected to survive discarding (Revill, 2011). Individuals with mantle lesions and trauma are also susceptible to developing bacterial sepsis (Sherrill et al., 2000). However, the short life-span of this species, its annual reproduction and its high fecundity means that population recovery from such effects should occur after a year.

Abrasion, due to trawling and dredging, may also remove biogenic structures such as seaweed and seagrass which are locations of attached eggs. If eggs have already been laid they are likely to be destroyed and the area is left as an unfavourable spawning ground (Bloor & Jackson, 2014).

Sensitivity assessment. Adults are able to move out of the way of a lot of danger but are at risk of being caught and/or damaged by fishing equipment. However, juveniles and eggs are more vulnerable due to their reduced ability to move out of the way. Therefore, resistance is assessed as ‘Low’ but with 'low' confidence. Resilience is probably ‘Medium’ and sensitivity is assessed as ‘Medium’.

Penetration or disturbance of the substratum subsurface

Benchmark. Damage to sub-surface features (e.g. species and physical structures within the habitat). Further detail

Evidence

Sepia officinalis is a mobile species and therefore is not likely to be affected by penetration by fishing gear, dredges or other activities. However, the primary defensive behaviour of juveniles or smaller, weaker, individuals is to bury into the sandy sea-floor. Penetration could therefore directly injury or damage the buried individual, affecting the recruitment rates for the population. Therefore, based on the evidence above (abrasion), resistance is assessed as ‘Low’ but with 'low' confidence. Resilience is probably ‘Medium’ and sensitivity is assessed as ‘Medium’.

Changes in suspended solids (water clarity)

Benchmark. A change in one rank on the WFD (Water Framework Directive) scale e.g. from clear to intermediate for one year. Further detail

Evidence

Sepia officinalis may benefit from reduced water clarity by acting as an external camouflage so that the species can preserve more energy. This may help reduce the chances of predation especially on the eggs of Sepia officinalis (Catarina et al., 2017). But, suspended solids may inhibit the species from effectively feeding by removing visual cues (Mäthger et al., 2006) as well as interfere with mating rituals. However, Sepia officinalis is a highly intelligent animal and is able to use other cues, such as chemical or audial, in order to track down prey and other individuals (Samson et al., 2014). Juveniles are able to catch shrimps with ease in complete darkness (Blanc et al., 1998). Furthermore, Jozet-Alves et al. (2013) suggested that Sepia officinalis may have an episodic-memory allowing the cuttlefish to remember key prey hotspots and feeding locations.

Sensitivity assessment. Resistance is likely to be ‘High’ but with ‘low’ confidence. Resilience is probably ‘High’ and sensitivity is, therefore, assessed as ‘Not sensitive’.

Smothering and siltation rate changes (light)

Benchmark. ‘Light’ deposition of up to 5 cm of fine material added to the seabed in a single discrete event. Further detail

Evidence

The species is highly mobile and therefore unlikely to be affected by smothering since it can relocate to more favourable conditions. Juveniles are also able to move and dig into and out of small and large grain sand (Boletzky, 1983). Eggs are usually laid on floating or suspended structures in the water column and therefore are unlikely to be affected by light sediment deposition (Bloor et al., 2013).

Sensitivity assessment. Resistance is, therefore, likely to be ‘High’. Resilience is ‘High’ by default and sensitivity is therefore assessed as ‘Not sensitive’.

Smothering and siltation rate changes (heavy)

Benchmark. ‘Heavy’ deposition of up to 30 cm of fine material added to the seabed in a single discrete event. Further detail

Evidence

The species is highly mobile and therefore unlikely to be affected by smothering since it can relocate to more favourable conditions. Juveniles are also able to move and dig into and out of deposited sediment (Boletzky, 1983). The duration of the digging and the juvenile’s ability to dig depends on the sediment (Mather, 1986). If there is a heavy deposition of coarse sand then juveniles should be able to dig straight out. As this benchmark is for the deposition of fine material and not hard gravel like substrata, there should be relatively low, if any, impact on the juveniles (Mather, 1986). Eggs are usually laid on floating or suspended structures in the water column and therefore are unlikely to be affected by heavy sediment (Bloor et al., 2013).

Sensitivity assessment. Resistance is therefore likely to be ‘High’. Resilience is probably ‘High’ and sensitivity is, therefore ‘Not sensitive’.

Litter

Benchmark. The introduction of man-made objects able to cause physical harm (surface, water column, seafloor or strandline). Further detail

Evidence

'Not assessed'. However, it is noted that man-made objects that have been left or dumped into the sea, such as ropes, are a popular spot for Sepia officinalis females to attach their eggs.

Electromagnetic changes

Benchmark. A local electric field of 1 V/m or a local magnetic field of 10 µT. Further detail

Evidence

'No evidence'

Underwater noise changes

Benchmark. MSFD indicator levels (SEL or peak SPL) exceeded for 20% of days in a calendar year. Further detail

Evidence

The statocyst is considered the primary sound detection organ in cephalopods. Alongside peripheral hairs and epidermal hairs, Sepia officinalis is able to detect local water movement by detecting vibrations (Hanlon & Messenger, 1996; Samson et al., 2014). The statocyst is also responsive for equilibrium and movement in the water column (Solé et al., 2017).

In aquarium facilities in Portaferry, Northern Ireland, 30 individual Sepia officinalis were subject to 210 seconds of playback of engine noise recorded from a car ferry (165 Db). The noise appeared to affect the colour changing behaviour and movement of the cuttlefish. Individuals changed colour more frequently and increased locomotion compared to a control group with a playback of ambient reef noises. These behaviours suggested an increase in stress level (Kunc et al., 2014). As cephalopods use complex movements and behaviour during courtship, mating and camouflage, noise pollution may increase predation risk and decrease the chances of reproduction (Kunc et al., 2014).

Noise was also reported to increase occurrences of jetting and inking (Hanlon & Messenger, 1996). The greatest intensity response e.g. inking, was found at the highest sound levels (100-300 Hz) (Samson et al., 2014) and above 140 Db. Sepia officinalis was able to habituate (get used to) the noise when identical sounds were played close together (Samson et al., 2014). This observation suggested that Sepia officinalis would not show a long-term response to sound.

Individuals exposed to levels of sound from 139-142 dB centred at 315-400 Hz revealed injuries to the statocyst. Immediately after exposure to the sound, spherical holes were found on the base of the hair cells and in the plasma membrane of the statocyst. After 48 h of sound exposure damage occurred on the internal epithelium and some hair cells were either partially or totally ejected from the sensory epithelium. This could result in permanent physical damage but due to the dissections needed for this study the long-term effects are still unknown (Solé et al., 2017). If the species is disturbed by noise it should swim away when it senses any vibrations. The viability of the species may be reduced if feeding or breeding periods are disrupted.

Sensitivity assessment. Sepia officinalis are able to undergo habituation to the sound but may change their behaviour, including mating behaviour. Internal damage has been caused by specific noise levels, meaning, the resistance to this pressure is probably ‘Medium’ albeit with ‘low’ confidence. Hence, resilience is probably ‘Medium’, and sensitivity has been assessed as ‘Medium’.

Introduction of light or shading

Benchmark. A change in incident light via anthropogenic means. Further detail

Evidence

Sepia officinalis appears to be sensitive to light. Under a bright light in Plymouth Marine Laboratory, the species buried themselves under gravel at the bottom of the tank. Under artificial light, that mirrored natural diffused daylight, adults showed increases in density (Denton & Gilpin-Brown, 1961). However, burying did not occur all the time during the periods of light exposure. If large cuttlefish were hungry, or if two males were in the same tank, they entered mid-water and remained there even under high light intensity.

Sexual migration is not always determined by temperature. Individuals have been seen to leave warmer waters and arrive in April when waters are still only 10°C. It is thought that photoperiod plays a role in determining the time at which sexually mature individuals migrate back inshore (Boucaud-Camou & Boismery, 1991). The photoperiod is the length of daily illumination received by the individual (Koueta et al., 2005). In the English Channel, therefore, inshore migration usually occurs around the spring equinox when the daily photoperiod increases (Koueta and Boucaud-Camou, 2003).

Hatching is also determined by the transition from light to dark (Koueta and Boucaud-Camou, 2003). Therefore, the absence of light is very important in synchronised hatching (Paulik et al., 1991) and reduced predation. Under a low photoperiod in a lab (8 h of light and 16 h of dark) growth rates were low for juveniles. Long photoperiods (24 h of light) in aquaculture resulted in a longer lifespan and larger individuals. However, gonad development appeared to be inhibited, allowing the animal to live longer but prohibited reproduction (Forsythe et al., 1994).

Cuttlefish adjust their camouflage depending on light intensity. In extremely low light (<0.001 lux) cuttlefish do not camouflage but instead retract their dermal chromophores and choose a pale appearance, suggesting a low energy response (Buresch et al., 2015). Under high light intensity camouflage is increased with more energy consumption. A danger of the increase in an extended period of illumination is that more energy will have to be prioritised for camouflage and not other processes such as growth or reproduction (Buresch et al., 2015).

Sensitivity assessment. Despite showing a behavioural response to light there is no evidence of death due to the effect of an introduction of light from an artificial source. Therefore, a resistance score of ‘High’ is recorded with ‘low’ confidence. Recoverability is probably ‘High’ and this species is therefore assessed as ‘Not Sensitive’ to the induction of light or shading.

Barrier to species movement

Benchmark. A permanent or temporary barrier to species movement over ≥50% of water body width or a 10% change in tidal excursion. Further detail

Evidence

There is evidence of gene flow between the English Channel and southern North Sea populations probably due to the mobility of this species. However, there is also clear genetic differences between the Atlantic and Mediterranean populations (Wolfram et al., 2006).

Sensitivity assessment. Sepia officinalis migrates to deep water to breed and returns to coastal waters to spawn. A barrier to movement (e.g. barrage) is likely to prevent this migration and, since the species has a short lifespan, result in loss of the local population affected by the barrier. If the barrier is temporary then recovery may be rapid (a few years). However, a permanent barrier may exclude Sepia officinalis from the affected area. Therefore, in the worst-case scenario of a permanent barrier, resistance is probably None, and a resilience is ‘Very low’ (as the barrier is permanent) and sensitivity is assessed as ‘High’. However, confidence in the assessment is ‘low’.

Death or injury by collision

Benchmark. Injury or mortality from collisions of biota with both static or moving structures due to 0.1% of tidal volume on an average tide, passing through an artificial structure. Further detail

Evidence

Collision with the individual due to grounding by vessels is addressed under (abrasion). Therefore, this pressure is ‘Not relevant’.

Visual disturbance

Benchmark. The daily duration of transient visual cues exceeds 10% of the period of site occupancy by the feature. Further detail

Evidence

Sepia officinalis have the ability to perceive and differentiate different objects from their background as long as they differ in contrast from the background by at least 15% (Mäthger et al., 2006). They are thought to have just one visual pigment that has a maximum absorption of green light (492 nm) (Mäthger et al., 2006). Sepia officinalis are thought to have reasonable ‘night-vision’, due to their nocturnal hunting and feeding behaviour (Castro & Guerra, 1989).

The species also appears to be colour-blind due to their inability to camouflage against and distinguish certain visual cues (Mäthger et al., 2006). When placed on a checkerboard of alternating blue and yellow shades of the same intensity, cuttlefish did not show a disruptive colouration suggesting it was unable to differentiate between the two colours of the same light intensity (Mäthger et al., 2006).

It has been proposed (John Rundle, personal communication, cited in Tonkins et al., 2015) that dark figures leaning over tanks may be interpreted as predators by captive cuttlefish. This may lead to a defence response such as digging, swimming, and inking.

Sensitivity assessment. The species has well-developed eyes so can detect movement sufficiently well to be susceptible to visual disturbance. However, the species will swim away or hide when any presence threatens, therefore, recovery is immediate. Visual cues may cause a behavioural response but due to the mobility of the species, the pressure is unlikely to cause mortality or interfere with reproduction. Hence, resistance is ‘High’, resilience is ‘High’, and the species is likely to be ‘Not sensitive’.

Genetic modification & translocation of indigenous species

Benchmark. Translocation of indigenous species or the introduction of genetically modified or genetically different populations of indigenous species that may result in changes in the genetic structure of local populations, hybridization, or change in community structure. Further detail

Evidence

There is evidence of gene flow between the English Channel and southern North Sea populations probably due to the mobility of this species. However, there is also clear genetic differences between the Atlantic and Mediterranean populations (Wolfram et al., 2006).  Therefore, the translocation of specimens between Mediterranean and Atlantic population may affect the genotypes of the resident populations. However, there is no evidence that this has or is likely to occur and no evidence to suggest that it would be detrimental for the receiving population.  

Introduction or spread of invasive non-indigenous species

Benchmark. The introduction of one or more invasive non-indigenous species (INIS). Further detail

Evidence

The invasive blue crab Callinectes sapidus is originally from the coasts of the western Atlantic but has now reached European waters. It inhabits the same habitat niche of sandy bottoms at 35 m in depth as Sepia officinalis. In culture, it has also shown to actively feed on Sepia officinalis eggs. This crab has to potential to be a risk to Sepia officinalis but there is currently no evidence of actual introduction, therefore ‘No evidence’ is recorded (Catarina et al., 2017).

Introduction of microbial pathogens

Benchmark. The introduction of relevant microbial pathogens or metazoan disease vectors to an area where they are currently not present (e.g. Martelia refringens and Bonamia, Avian influenza virus, viral Haemorrhagic Septicaemia virus). Further detail

Evidence

Some bacteria are not pathogenic but are in fact symbiotic and occur in the accessory rudimental gland in cuttlefish (Grigioni & Boucher-rodoni, 2002). It is thought that these bacteria are responsible for the colour change in the gland from white to bright red/orange which signifies the individual is sexually mature (Grigoni & Boucher-Rodoni, 2002). Sepia officinalis also has naturally occurring Gammaproteobacteria, e.g. Vibrionaceae, in the gills and oesophagus. These bacteria appear to be resilient to the common animal antibiotic enrofloxacin (Lutz et al., 2018).

A common infection spot in Sepia officinalis is in the digestive tract and stomach epithelium (Hanlon & Forsythe, 1990). A virus similar in structure to a retrovirus in vertebrates was found in the stomachs of wild cuttlefish (Hanlon & Forsythe, 1990). Microbes were recorded on the outside of Sepia officinalis egg cases that reduced the oxygen available to diffuse into the egg (Cronin & Seymour, 2000).

The coccidian Aggregata eberthi appears to use the digestive tract of the cuttlefish as part of their sexual reproduction (Gestal et al., 2002). This has been known to lead to an increase in gut infections, which reduces the function of the digestive system and limits the absorption of nutrients (Gestal et al., 2002). However, there is little evidence of direct mortality as a result of microbial infection (Hochberg, 1990).

Fungal infections can appear on Sepia officinalis but these are usually the result of trauma to the skin or a weakening of the immune system (Harms et al., 2006). Cells known as ovoid cells in the heart tissue are known to target bacterial toxins in the blood. This shows a strong immune response to microbial infection and suggests a tolerance to them (Beuerlin & Schipp, 1998).

Despite their resistance, inflammation and secondary bacterial infections occur generally in cuttlefish that have sustained trauma or mantle lesions. Septicaemia (Vibrio spp.) caused by mantle erosion from trauma and/or collision resulted in the death of 4/7 cultured cuttlefish under standard culturing conditions (Sherrill et al., 2000).

Sensitivity assessment. Sepia officinalis appear to be relatively tolerant to microbial infections but once damaged due to trauma appear less resistant, resulting in a score of ‘Medium’. Recovery is probably ‘Medium’ and sensitivity is, therefore ‘Medium’.

Removal of target species

Benchmark. Removal of species targeted by fishery, shellfishery or harvesting at a commercial or recreational scale. Further detail

Evidence

In many areas, Sepia officinalis is fished at the maximum sustainable rate but in others, there has been a recent decline in captures in heavily fished areas. It is the most abundant cephalopod species fished in the North East Atlantic with annual landings ranging from 40,000-50,000 (ICES, 2009). The UK cuttlefish landings for UK vessels in 2015 was ca. 6000 tonnes (MMO, 2016; cited in ICES, 2017(b)). The primary mode of fishing is trawling but cuttlefish are also caught by artisanal fisheries using pots and traps (ICES, 2003). The peak inshore fishing season, unfortunately, coincides with the peak spawning period meaning adults have a limited time to reproduce and replenish the subsequent population before they are fished (ICES, 2003).

In inshore French waters, Sepia officinalis is harvested by traps that selectively remove males prior to reproduction, trawls that capture a high percentage of females and juveniles, and nets that capture an even ratio of adult males and females (du Sel et al., 1997). Females have been shown to mate with multiple males meaning a reduction in males may not affect the fecundity of the population drastically.

Sepia officinalis eggs are removed unintentionally as the females attach them to cuttletraps from March to September. The fishermen, fishing for adult cuttlefish, do not tend to place the traps straight back into the ocean and instead leave the traps and eggs on the pontoon to be desiccated (Blanc & Daguzan, 1998). Due to the lack of generation overlap, the mortality of eggs is detrimental to the recruitment of the population.

There is an issue of high discarding rates within the cephalopod fisheries. In 2008, an estimated 306 tonnes of small cuttlefish were discarded in the south-west of England (CEFAS; cited in Revill, 2011). From interviews with fishermen, a major reason for discarding juveniles is the hope that they will grow bigger and to a more valuable size for the following years capture (Revill, 2011). Sepia officinalis from a large beam trawler operating in the offshore waters of south-west UK were examined during a single fishing trip for signs of damage and survival (Revill, 2011). Analysis showed that 16% of these small cuttlefish (<15 cm) died later after their injuries from capture, 68% died whilst in the trawl or on the deck, and only 16% survived capture and deck sorting and were expected to survive discarding (Revill, 2011).

There is currently no routine monitoring or assessment scheme in place for the English Channel Sepia officinalis stock (Gras et al., 2014). During the sea trials, large cuttlefish were able to survive the trauma of trawling and deck sorting more than the delicate smaller cuttlefish.  The damage to the smaller cuttlefish was damage to the skin and even internal cuttlebone suggesting smaller cuttlefish are more fragile and weaker than adults (Revill, 2011). As there is no current minimum landing size of cuttlefish in the UK. Therefore small cuttlefish are more vulnerable to catch and discarding than adults (British Sea Fishing, 2018).

Landings are also increasing globally. For example, in the English Channel, total annual landings have increased from 430t in 1992 to 17,400t in 2014 (Gras et al., 2016). Dunn (1999) suggested that as the market value is increased, cephalopods could becoming more popular for fishermen, which may begin to hinder Sepia officinalis stocks in the future.

Sensitivity assessment. Sepia officinalis have ‘Low’ resistance to removal. Resilience is likely to be ‘Medium’ as there is no current recorded global decline in stocks. However, stocks of Sepia officinalis are currently able to just about continue replenishing the current population but if fishing pressures increase the likelihood of replenishment will be reduced (ICES, 2017(b)). Sensitivity is, therefore, 'Medium’.

Removal of non-target species

Benchmark. Removal of features or incidental non-targeted catch (by-catch) through targeted fishery, shellfishery or harvesting at a commercial or recreational scale. Further detail

Evidence

Extraction of another species will not have a strong effect on this species as their prey is very varied and they have no dependence on one particular species. Sepia officinalis have a varied diet from amphipods to gobies and sand eels. In extreme cases, they may even become cannibalistic, preying on smaller individuals (Castro & Guerra, 1990). Prey size is also selective, with adult Sepia officinalis choosing fish 25-80% and crabs 20-40% the size of their mantle length (Blanc et al., 1999). Predators of Sepia officinalis include; sharks, lobsters and other cephalopods (Catarina et al., 2007). The extraction of non-target species is not thought to affect Sepia officinalis from a biological point of view. Instead, the biggest risk to the species due to this removal is; removal of eggs by accident (see abrasion) and by-catch.

In the Mersin province, Turkey, 10g of Sepia officinalis were caught as by-catch using one trawl from September 2004 to April 2005. The target fish were; mullet, goatfish and shrimp (Atar & Malal, 2010). In Algarve (southern Portugal), Sepia officinalis are occasionally caught in tuna traps (Neves dos Santos et al., 2002). Many eggs are laid on cuttletraps during spawning periods. When removed from water fishermen are not interested in collecting the eggs. Instead, they are usually left on the pontoon until further use resulting in either mortality or significant damage (Blanc & Daguzan, 1998).

Sensitivity assessment. Resistance is probably ‘Medium’ but with ‘Low’ confidence due to a lack of available by-catch figures. Resilience is probably ‘Medium’ and sensitivity is ‘Medium’