"marea roja" meaning in Spanish

{
  "forms": [
    {
      "form": "mareas rojas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "marea roja f (plural mareas rojas)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Spanish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2013 July 9, Alan Gainza Miranda, “Científicos de UCR encuentran arrecife de Samara y Carrillo en mal estado”, in La Voz de Guanacaste:",
          "text": "Los motivos fundamentales por los que se ha degradado el arrecife en estos momentos son las mareas rojas y las extracciones de coral por parte de los humanos.",
          "type": "quote"
        }
      ],
      "glosses": [
        "red tide"
      ],
      "id": "en-marea_roja-es-noun-K37PaVN9",
      "links": [
        [
          "red tide",
          "red tide"
        ]
      ],
      "tags": [
        "feminine"
      ],
      "wikipedia": [
        "es:marea roja"
      ]
    }
  ],
  "word": "marea roja"
}

{
  "forms": [
    {
      "form": "mareas rojas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "marea roja f (plural mareas rojas)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Pages with 1 entry",
        "Pages with entries",
        "Requests for translations of Spanish quotations",
        "Spanish countable nouns",
        "Spanish entries with incorrect language header",
        "Spanish feminine nouns",
        "Spanish lemmas",
        "Spanish multiword terms",
        "Spanish nouns",
        "Spanish terms with quotations"
      ],
      "examples": [
        {
          "ref": "2013 July 9, Alan Gainza Miranda, “Científicos de UCR encuentran arrecife de Samara y Carrillo en mal estado”, in La Voz de Guanacaste:",
          "text": "Los motivos fundamentales por los que se ha degradado el arrecife en estos momentos son las mareas rojas y las extracciones de coral por parte de los humanos.",
          "type": "quote"
        }
      ],
      "glosses": [
        "red tide"
      ],
      "links": [
        [
          "red tide",
          "red tide"
        ]
      ],
      "tags": [
        "feminine"
      ],
      "wikipedia": [
        "es:marea roja"
      ]
    }
  ],
  "word": "marea roja"
}