A report on the state of the marine environment and of marine species in 2020 in south-west England has just been published by the Plymouth-based Marine Biological Association (MBA). One of the report editors, MBA Associate Fellow Dr Keith Hiscock, thanked the editors of eleven different sections for bringing-together observations made during 2020 and summarized that, as always, they included 'highlights' and 'lowlights'.

Colleagues at the Plymouth Marine Laboratory had recorded an exceptionally widespread bloom of coccolithophores (a type of plankton that has beautifully ornamented calcareous plates) in June and early July, which developed after a period of very warm, dry, settled, sunny weather whilst also recording that phytoplankton biomass was low overall, part of an ongoing, long-term declining trend which is particularly prevalent in the summer months. Many observations by the included unusually widespread strandings of Portugese man-o'-war – a jellyfish that packs a very powerful sting – early and late in the year.

Covid-19 restrictions meant that the frequency of some surveys was reduced including of non-native species that are being undertaken by the Marine Biological Association. However, observations by various groups and individuals indicated some spread of already-present invasive species whilst studies by the Cornwall Wildlife Trust documented a significant increase in the occurrence and abundance of Pacific oysters over the last few years including in some inlets in Cornwall. Remarkably, in terms of its apparent remoteness, Pacific oysters were reported for the first time at Lundy.

There may have been an 'upside' for wildlife during Covid-19 restrictions. For seahorses, during a survey dive at one particular location in May, 16 spiny seahorses were seen and, on another in June, 21 were observed. Over this period 46 individual animals were identified. However, the observations were all in the ‘Lockdown’ period. When regulations were eased up to 400 vessels per day were observed anchoring in the area and very few seahorses could be found. For seals, the Cornwall Seal Group Research Trust recorded that disturbance was down in 2020. Serious disturbance incidents dropped from 141 to 64 and seals affected from 614 to 192 during lockdown between February and July inclusive. Things then deteriorated with August being our worst August on record for the number of seals affected (150 seals).

For fish, reports of basking shark and triggerfish were lower again compared to as long as 10 years ago, but sunfish sightings were up. Rare fish records included a sailfin roughshark, a sailfin dory, a white sea bream, an imperial blackfish and the first confirmed record of an Atlantic croaker for Britain and Ireland.

Systematic observations of seals emphasises the value of long-term data sets in spotting change. Phenology shifts appear to be taking place in southwest seals. Peak haul out season was earlier, moving from April in 2013/14 to March (for 5 years) to Feb (for 2 years) and even Jan and Dec (for 1 year each). Likewise, the pupping season, that used to peak in October, has moved to September for the last 2 years and is shorter and more compressed than it used to be. Alongside this, seals have recolonised new haul outs not previously recorded by the Cornwall Seal Group Research Trust on the Lizard and at West Cornwall, whilst haul outs have shifted from one side of the headland to the other on the Roseland Peninsula.

For coastal birds, tern species showed a fairly productive year, usually as a result of conservation management. Kittiwakes showed average or worse than average productivity, which is a concern for the south west’s dwindling kittiwake colonies. Guillemots showed good productivity on Lundy, but puffins did not – although this species is notoriously difficult to monitor accurately. Sightings in the non-breeding season were affected by the reduced effort resulting from Covid-19 restrictions, with reported numbers of most shearwater species lower than usual. Occasional rarities were recorded, including two brown boobies, various scarce gulls and terns, a rare band-rumped storm petrel, and a black-browed albatross.

2020 was a 'bumper year' for baleen whale sightings in south-west England. Four species were observed, with record numbers of sightings of humpback and fin whales, and a near-record number of minke whale sightings recorded. One study demonstrated the presence of a (loose) pod of about 40 bottlenose dolphins in the south-west with the population ranging between North Devon and Sussex. Porpoise feature frequently in the sightings of whales and dolphins with a particularly unusual sighting and video clip of porpoise made by anglers on the River Tone at Burrowbridge in mid-April. There were several sightings of large pods of common dolphin included one estimated to 400+ leaving Teignmouth and heading toward Dorset.

Every year brings sightings and events that surprise. The presence of a large moulting aggregation of spiny spider crabs below the jetty at Lundy was a 'first' for the island and a remarkable sight for anyone going snorkelling there.

Fisheries and management and the extent of plastic pollution also feature in the report. There were changes in both national and regional regulations to protect fisheries but Covid-19 lockdown led to a fall in demand for fish and shellfish, loss of export markets, disruption in supply chains and falls in prices as markets disappeared. The recovery (since about 2014) of populations of spiny lobsters in parts of the south-west after their local extermination in the late 1960s and early 1970s continued in 2020 together with the remarkable 'return' of bluefin tuna to the south-west which provided many photo-opportunities for those out at sea. The 'Benyon review' of Highly Protected Marine Areas was launched on World Oceans Day on 8th June.

In drawing together all of the separate sections of the report, Keith Hiscock observed "the highlight of the year for me was realising the extent to which otters are now being seen in coastal areas and being told that, over 200 years ago, otters were considered a marine species that occasionally occurred in rivers."

The report can be accessed on www.swmecosystems.co.uk/annual-reports.

Aug 11, 2021 By maypla