Two weeks ago (early in the morning, Dec. 31), I witnessed a stranding of euphausiids in Labrolette Bay, St. Lucia (Caribbean side of the Island just north of Castries). The entire length of the beach was affected (1-2 m wide patches of washed up individuals) but I do not know how far beyond that beach the stranding may have occurred.
I observed that about half of the euphausiids in the water, before they reached the beach, were dead (they had turned white) while the other half were still clear and moving about. They were of a consistent size, about 1 cm in length. I did not observe anything unusual about the sea state and surroundings, a fairly average day in terms of weather and sea condition and no sign of unusual runoff. I have several pictures of the euphausiids washing up on the beach and a fairly good close up of an individual (attached). I know that many species (about 34) occur in the Caribbean and surrounds.
I have observed euphausiids brought to the surface in the Bay of Fundy (Canada) by upwellings where they were preyed upon by 10s of thousands of sea birds and whales. I have read about beach strandings elsewhere in the world but not in the Caribbean.
Can this be a post-spawning mortality? We have observed dense spawning aggregations of euphausiid Thysanoessa rachii on western Bering Sea shelf in May. Strong coastward wind might blow them on the beach in such situation.
As for beach strandings, large copepod Neocalanus cristatus were observed in abundance on the sand beach in the Mordvinova Bay (Southeastern Sakhalin Island). It was unusual since reproduction of Neocalanus spp. occurred in the deep layers (>500 m) and adult Neocalanus copepods usually reside these depths. We could not reveal a reason of this stranding.
Unfortunately, I was unable to save samples or examine specimens in detail (on vacation) but as noted above, I did note the 50/50 split in live vs. dead individuals in the water. Weather and sea conditions were not out of the ordinary.
I send you some pubblications on the beach stranding of euphausiids and other crustaceans along the Strait of Messina (Sicily,Italy). I hope that these informations can be usefull for your study.
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